Leaf litter is an important mediator of soil respiration in an oak-dominated forest

Treesearch

Jared L. DeForest; Jiquan Chen; Steve G. McNulty

2009-01-01

The contribution of the organic (O) horizon to total soil respiration is poorly understood even though it can represent a large source of uncertainty due to seasonal changes in microclimate and O horizon properties due to plant phenology. Our objectives were to partition the CO2 effluxes of litter layer and mineral soil from total soil...

Permafrost Thaw, Soil Moisture and Plant Community Change Alter Organic Matter Decomposition in Alaskan Tundra

NASA Astrophysics Data System (ADS)

Natali, S.; Mauritz, M.; Pegoraro, E.; Schuur, E.

2015-12-01

Climate warming in arctic tundra has been associated with increased plant productivity and a shift in plant community composition, specifically an increase in shrub cover, which can impact soil organic matter through changes in the size and composition of the leaf litter pool. Shifts in litter quantity and quality will in turn interact with changes in the soil environment as the climate continues to warm. We examined the effects of permafrost thaw, soil moisture changes, and plant community composition on leaf litter decomposition in an upland tundra ecosystem in Interior Alaska. We present warming and drying effects on decomposition rates of graminoid-dominated and shrub-dominated leaf litter mixtures over three years (2 cm depth), and annual decomposition of a common cellulose substrate (0-10 cm and 10-20 cm) over five years at a permafrost thaw and soil drying experiment. We expected that warming and drying would increase decomposition, and that decomposition would be greater in the shrub litter than in the graminoid litter mix. Decomposition of Betula nana, the dominant shrub, was 50% greater in the shrub-dominated litter mix compared to the graminoid-dominated litter. Surprisingly, there was no significant difference in total litter mass loss between graminoid and shrub litter mixtures, despite significant differences in decomposition rates of the dominant plant species when decomposed alone and in community mixtures. Drying decreased decomposition of B. nana and of the shrub community litter overall, but after two years there was no detected warming effect on shrub-community decomposition. In contrast to leaf litter decomposition, both warming and drying increased decomposition of the common substrate. Warming caused an almost twofold increase in cellulose decomposition in surface soil (0-10cm), and drying caused a twofold increase in cellulose decomposition from deeper organic layer soils (10-20cm). These results demonstrate the importance of interactions among temperature, moisture and vegetation changes on organic matter decomposition, and the potential for increased plant productivity and vegetation changes to alter the size and composition of the soil organic matter pool.

Leaf litter production of mahogany along street and campus forest of Universitas Negeri Semarang, Indonesia

NASA Astrophysics Data System (ADS)

Martin, F. P.; Abdullah, M.; Solichin; Hadiyanti, L. N.; Widianingrum, K.

2018-03-01

The leaf litter of trees along the existing streets on campus UNNES if not managed properly will be scattered and become garbage. Leaf litter Production in UNNES campus is not known for certain. UNNES does not own mapping of leaf litter Production of dominant tree species on campus. This cause leaf waste management is not optimal yet. There is still a lot of leaf litter that is discharged (not processed) because it exceeds the capacity of the fertilizer production equipment in the compost house. Aims of this study were to examine leaf litter production of dominant trees in Universitas Negeri Semarang and evaluate the relationship between leaf litter and average rainfall. Purposive sampling method placed pouches of nylon gauze measuring 1 × 1 mm2 as litter trap container with size 1 x l m2 (10 points mounted along street and campus forest). Litter trap mounted at the height of 50 cm above ground level. Leaf litter will be taken once a week for three months to observe the litter production. The litter was then dried by the oven at 70 ° C for 48 hours to obtain constant dry weight. Based on the results of the research, it was known that Mahogany tree in UNNES campus area has the potential to produce the litter of about 10 ton/ha / 3months in campus forest area and 2.5 ton/ha / 3months along campus street. There is a significant relationship between litter production of Mahogany leaves and precipitation during August - October 2017.

Species-specific Mechanisms Contributing to the Mesophication of Upland Oak Stands in the Absence of Fire

NASA Astrophysics Data System (ADS)

Babl, E. K.; Alexander, H. D.; Siegert, C. M.; Willis, J. L.; Berry, A. I.

2017-12-01

Upland oak forests of the eastern United States are shifting dominance towards shade-tolerant, fire-intolerant species. This shift is hypothesized to be driven by anthropogenic fire suppression and lead to mesophication, a positive feedback loop where shade-tolerant, fire-sensitive species (i.e. mesophytes) create a cool, moist understory, reducing forest flammability and promoting their own proliferation at the expense of pyrophytic, shade-intolerant species such as oaks. There have been few empirical studies identifying mechanisms of mesophication, and these studies have yet to extensively explore potential mesophytes other than red maple (Acer rubrum). To address this issue, we sampled four hypothesized mesophytes (A. rubrum, A. saccharum, Carya glabra, and Fagus grandifolia) and two upland oak species (Quercus alba and Q. montana) across a gradient of sizes (20-60 cm DBH) in western Kentucky. We quantified canopy, bark, and leaf litter traits among upland oaks and mesophytes that may lead to differences in forest flammability. Preliminary results show that mesophytes had thinner and smoother bark than upland oaks and an increased canopy volume (normalized to stem volume), traits known to influence water movement through the canopy and understory microclimate. Maple leaf litter also decomposed faster, which could decrease fuel loads; after 6 months, red and sugar maple leaf litter lost 37% of original mass compared to 32%, 22%, and 14% mass loss in hickory, oak, and American beech litter, respectively. Furthermore, volumetric soil moisture of the soil organic layer beneath the canopies of mesophytes was 62% moister two days following a rainfall event compared to oaks. These differences in soil organic layer water retention after rainfall could lead to fuel discontinuity. These findings suggest that mesophytes may alter future forest flammability through their bark, canopy, and leaf litter traits which may modify fuel moisture, loads, and continuity and that a mesophication tipping point may eventually occur that prevents restoration efforts using prescribed fire.

Metal release from contaminated leaf litter and leachate toxicity for the freshwater crustacean Gammarus fossarum.

PubMed

Maunoury-Danger, Florence; Felten, Vincent; Bojic, Clément; Fraysse, Fabrice; Cosin Ponce, Mar; Dedourge-Geffard, Odile; Geffard, Alain; Guérold, François; Danger, Michael

2018-04-01

Industrialization has left large surfaces of contaminated soils, which may act as a source of pollution for contiguous ecosystems, either terrestrial or aquatic. When polluted sites are recolonized by plants, dispersion of leaf litter might represent a non-negligible source of contaminants, especially metals. To evaluate the risks associated to contaminated leaf litter dispersion in aquatic ecosystems, we first measured the dynamics of metal loss from leaf litter during a 48-h experimental leaching. We used aspen (Populus tremula L.), a common tree species on these polluted sites, and collected leaf litter on three polluted sites (settling pond of a former steel mill) and three control sites situated in the same geographic area. Then, toxicity tests were carried out on individuals of a key detritivore species widely used in ecotoxicology tests, Gammarus fossarum (Crustacea, Amphipoda), with uncontaminated and contaminated leaf litter leachates, using a battery of biomarkers selected for their sensitivity to metallic stress. Leaf litters collected on polluted sites exhibited not only significantly higher cadmium and zinc concentrations but also lower lignin contents. All leaf litters released high amounts of chemical elements during the leaching process, especially potassium and magnesium, and, in a lesser extent, phosphorus, calcium, and trace metals (copper, cadmium, and zinc but not lead). Toxicity tests revealed that the most important toxic effects measured on G. fossarum were due to leaf litter leachates by themselves, whatever the origin of litter (from polluted or control sites), confirming the toxicity of such substances, probably due to their high content in phenolic compounds. Small additional toxic effects of leachates from contaminated leaf litters were only evidenced on gammarid lipid peroxidation, indicating that contaminated leaf litter leachates might be slightly more toxic than uncontaminated ones, but in a very reduced manner. Further studies will be required to verify if these patterns are generalizable to other species and to investigate the effects of contaminated leaf litter ingestion by consumers on aquatic food webs. Nevertheless, our results do not permit to exclude potential chronic effects of an exposure to contaminated leaf litter leachates in aquatic ecosystems.

The fate of nitrogen mineralized from leaf litter — Initial evidence from 15N-labeled litter

Treesearch

Kathryn B. Piatek

2011-01-01

Decomposition of leaf litter includes microbial immobilization of nitrogen (N), followed by N mineralization. The fate of N mineralized from leaf litter is unknown. I hypothesized that N mineralized from leaf litter will be re-immobilized into other forms of organic matter, including downed wood. This mechanism may retain N in some forests. To test this hypothesis, oak...

Fate of leaf litter deposits and impacts on oxygen availability in bank filtration column studies.

PubMed

Bayarsaikhan, Uranchimeg; Filter, Josefine; Gernert, Ulrich; Jekel, Martin; Ruhl, Aki Sebastian

2018-07-01

Degradation of particulate organic carbon (POC) such as leaf litter might deplete dissolved oxygen within the upper layers of bank filtration, an efficient and robust barrier for pathogens and for various organic micro-pollutants (OMP) in water supply systems worldwide. The degradation of OMP during bank filtration depends on the redox conditions. The present study aimed at identifying the impacts and fates of different local leaves on the oxygen consumption and the possible biological degradation of indicator OMP. Oxygen concentrations initially decreased within the columns from around 8 mg/L in the influent to low concentrations indicating extensive consumption within a short travel distance. Still a substantial oxygen consumption was observed after 250 days. OMP concentrations were not significantly affected by the microbial processes. A layer of calcium carbonate crystallites was observed on the POC layer. Some leaf fragments appeared to be persistant towards degradation and the carbon content relative to nitrogen and sulfur contents decreased within 250 days. The results demonstrate that trees at bank filtration sites might have a strong long-term impact on the subsurface redox conditions. Copyright © 2018 Elsevier Inc. All rights reserved.

Litter dynamics in two Sierran mixed conifer forests. II. Nutrient release in decomposing leaf litter

USGS Publications Warehouse

Stohlgren, Thomas J.

1988-01-01

The factors influencing leaf litter decomposition and nutrient release patterns were investigated for 3.6 years in two mixed conifer forests in the southern Sierra Nevada of California. The giant sequoia–fir forest was dominated by giant sequoia (Sequoiadendrongiganteum (Lindl.) Buchh.), white fir (Abiesconcolor Lindl. & Gord.), and sugar pine (Pinuslambertiana Dougl.). The fir–pine forest was dominated by white fir, sugar pine, and incense cedar (Calocedrusdecurrens (Torr.) Florin). Initial concentrations of nutrients and percent lignin, cellulose, and acid detergent fiber vary considerably in freshly abscised leaf litter of the studied species. Giant sequoia had the highest concentration of lignin (20.3%) and the lowest concentration of nitrogen (0.52%), while incense cedar had the lowest concentration of lignin (9.6%) and second lowest concentration of nitrogen (0.63%). Long-term (3.6 years) foliage decomposition rates were best correlated with initial lignin/N (r2 = 0.94, p r2 = 0.92, p r2 = 0.80, p < 0.05). Patterns of nutrient release were highly variable. Giant sequoia immobilized N and P, incense cedar immobilized N and to a lesser extent P, while sugar pine immobilized Ca. Strong linear or negative exponential relationships existed between initial concentrations of N, P, K, and Ca and percent original mass remaining of those nutrients after 3.6 years. This suggests efficient retention of these nutrients in the litter layer of these ecosystems. Nitrogen concentrations steadily increase in decomposing leaf litter, effectively reducing the C/N ratios from an initial range of 68–96 to 27–45 after 3.6 years.

Technetium-99 cycling in maple trees: characterization of changes in chemical form.

PubMed

Garten, C T; Lomax, R D

1989-08-01

Prior field studies near an old radioactive waste disposal site at Oak Ridge, TN, indicated that following root uptake, metabolism by deciduous trees rendered 99Tc less biogeochemically mobile than expected, based on chemistry of the pertechnetate (TcO-4) anion. Subsequently, the form of technetium (Tc) in maple tree (Acer sp.) sap, leaves, wood and forest leaf litter was characterized using one or more of the following methods: dialysis, physical fractionation, chemical extraction, gel permeation chromatography, enzymatic extraction, or thin layer chromatography (TLC) on silica gel. Chromatography (Sephadex G-25) of TcO-4 incubated in vitro with tree sap showed it to behave similar to TcO-4 anion. When labeled wood and leaf tissues were processed using a tissue homogenizer, 15% and 40%, respectively, of the Tc was solubilized into phosphate buffer. Most (65% to 80%) of the solubilized Tc passing a 0.45-micron filter also passed through an ultrafiltration membrane with a nominal molecular weight cutoff of 10,000 atomic mass units (amu). A majority (72% to 80%) of the Tc in wood could be chemically removed by successive extractions with ethanol, water and weak mineral acid. These same extractants removed only 23% to 31% of the Tc from maple leaves or forest floor leaf litter. Most of the Tc in leaves and leaf litter was removed only by strongly alkaline reagents typically used to release structural polysaccharides (hemicelluloses) from plant tissues. Chromatography (Sephadex G-25) of the ethanol-water extract from wood and the alkaline extract from leaves demonstrated that Tc in these extracts was not principally TcO-4 but was complexed with molecules greater than 1000 amu. Incubations of leaf and wood homogenates with protease approximately doubled the amount of Tc released from contaminated tissues. Ultrafiltration of protease-solubilized Tc from leaves and wood showed that 40% and 93%, respectively, of the Tc was less than 10,000 amu. TLC of the less than 10,000 amu fraction indicated the presence of TcO-4 in wood but not in leaves. In the leaf, TcO-4 is converted to less soluble forms apparently associated with structural components of leaf cell walls. This conversion explains why 99Tc is not easily leached by rainfall from tree foliage and why 99Tc appears to accumulate in forest floor leaf litter layers at the Oak Ridge study site.

Leaf litter decomposition rates increase with rising mean annual temperature in Hawaiian tropical montane wet forests

PubMed Central

Bothwell, Lori D.; Giardina, Christian P.; Litton, Creighton M.

2014-01-01

Decomposing litter in forest ecosystems supplies nutrients to plants, carbon to heterotrophic soil microorganisms and is a large source of CO2 to the atmosphere. Despite its essential role in carbon and nutrient cycling, the temperature sensitivity of leaf litter decay in tropical forest ecosystems remains poorly resolved, especially in tropical montane wet forests where the warming trend may be amplified compared to tropical wet forests at lower elevations. We quantified leaf litter decomposition rates along a highly constrained 5.2 °C mean annual temperature (MAT) gradient in tropical montane wet forests on the Island of Hawaii. Dominant vegetation, substrate type and age, soil moisture, and disturbance history are all nearly constant across this gradient, allowing us to isolate the effect of rising MAT on leaf litter decomposition and nutrient release. Leaf litter decomposition rates were a positive linear function of MAT, causing the residence time of leaf litter on the forest floor to decline by ∼31 days for each 1 °C increase in MAT. Our estimate of the Q10 temperature coefficient for leaf litter decomposition was 2.17, within the commonly reported range for heterotrophic organic matter decomposition (1.5–2.5) across a broad range of ecosystems. The percentage of leaf litter nitrogen (N) remaining after six months declined linearly with increasing MAT from ∼88% of initial N at the coolest site to ∼74% at the warmest site. The lack of net N immobilization during all three litter collection periods at all MAT plots indicates that N was not limiting to leaf litter decomposition, regardless of temperature. These results suggest that leaf litter decay in tropical montane wet forests may be more sensitive to rising MAT than in tropical lowland wet forests, and that increased rates of N release from decomposing litter could delay or prevent progressive N limitation to net primary productivity with climate warming. PMID:25493213

Leaf litter bags as an index to populations of northern two-lined salamanders (Eurycea bislineata)

USGS Publications Warehouse

Chalmers, R.J.; Droege, S.

2002-01-01

Concern about recent amphibian declines has led to research on amphibian populations, but few statistically tested, standardized methods of counting amphibians exist. We tested whether counts of northern two-lined salamander larvae (Eurycea bislineata) sheltered in leaf litter bags--a relatively new, easily replicable survey technique--had a linear correlation to total number of larvae. Using experimental enclosures placed in streams, we compared number of salamanders found in artificial habitat (leaf litter bags) with total number of salamanders in each enclosure. Low numbers of the animals were found in leaf litter bags, and the relative amount of variation in the index (number of animals in leaf litter bags compared to total number of animals in stream enclosures) was high. The index of salamanders in leaf litter bags was not significantly related to total number of salamanders in enclosures for two-thirds of the replicates or with pooled replicates (P= 0.066). Consequently, we cannot recommend using leaf litter bags to index populations of northern two-lined salamanders.

Biochemical Composition Suggests Different Roles of Leaf Litter and Fine Roots in Soil Carbon Formation

NASA Astrophysics Data System (ADS)

Xia, M.; Pregitzer, K. S.; Talhelm, A. F.

2012-12-01

Plant litter is a major source of soil organic carbon (C). This litter is not homogenous, but instead primarily composed of fine root and leaf litter that adapted to different physiological functions. These unique functions suggest that root and leaf litter likely have different biochemical traits, and thus different decomposition patterns. However, few studies have compared their substrate quality and contributions to soil C. Also, much less attention has been given to fine roots although they can represent a substantial litter production. Here we hypothesize that 1) leaf litter and fine roots have different substrate quality as they are highly different in biochemical composition; 2) the biochemical composition of leaf litter and fine roots responds differently to the simulated nitrogen (N) deposition. To test these hypotheses, we collected leaf litter and fine roots of Acer saccharum (the dominant species in the northern temperate ecosystems we studied) in both ambient and N addition treatment plots at four sites of Michigan N deposition gradient study. We quantified ten biochemical components thought to be important on decomposition. Strikingly, we found a consistently three-fold higher lignin concentration in fine roots than that in leaf litter (P< 0.01). On average, lignin concentration of fine roots was 45.4±0.3% while that of leaf litter was 13.5±0.2%. Lignin has been considered highly recalcitrant and hypothesized as the major precursor of humus substance. Condensed tannin (CT) concentration in fine roots (13.13±0.51%) was also substantially higher than that in leaf litter (P< 0.01, 4.63±0.42 %). Tissue CT can inhibit litter decay by both precipitating proteins and by having antimicrobial properties. In contrast, fine roots exhibited lower concentrations of non-structural carbohydrates (NSC), soluble phenolics, and holocellulose (hemicelluloses & cellulose) than leaf litter (P< 0.01). These components are considered more easily accessible, and may stimulate the decay of lignin by providing required energy. Therefore, fine roots of Acer saccharum have a relatively recalcitrant nature based on their distinct biochemical composition, suggesting fine roots may be the major driver of soil carbon formation in the ecosystems we studied. Litter type and N addition had significant interactions on lignin, holocellulose, and NSC (P< 0.05), indicating these traits of different litter types respond differently to N addition. In leaf litter, the concentrations of lignin, NSC, and bound CT were affected by N addition (P< 0.05). By contrast, N addition only reduced the soluble protein concentration in fine roots (P< 0.05). Hence, substrate quality of leaf litter and fine roots responds differently to the simulated N deposition, and may eventually lead to different responses in decomposition pattern. This is one of few studies comparing the detailed biochemical profile of leaf litter and fine roots in a dominant tree species. Different biochemical traits of fine roots and leaf litter may reflect the different specializations for their physiological functions. This work highlights the importance of fine root in the soil carbon formation due to its recalcitrant nature, and emphasizes the necessity of differentiating the responses of leaf litter and fine root decompositions to environmental changes when modeling biogeochemical cycles.

Effects of forest management practices in temperate beech forests on bacterial and fungal communities involved in leaf litter degradation.

PubMed

Purahong, Witoon; Kapturska, Danuta; Pecyna, Marek J; Jariyavidyanont, Katalee; Kaunzner, Jennifer; Juncheed, Kantida; Uengwetwanit, Tanaporn; Rudloff, Renate; Schulz, Elke; Hofrichter, Martin; Schloter, Michael; Krüger, Dirk; Buscot, François

2015-05-01

Forest management practices (FMPs) significantly influence important ecological processes and services in Central European forests, such as leaf litter decomposition and nutrient cycling. Changes in leaf litter diversity, and thus, its quality as well as microbial community structure and function induced by different FMPs were hypothesized to be the main drivers causing shifts in decomposition rates and nutrient release in managed forests. In a litterbag experiment lasting 473 days, we aimed to investigate the effects of FMPs (even-aged timber management, selective logging and unmanaged) on bacterial and fungal communities involved in leaf litter degradation over time. Our results showed that microbial communities in leaf litter were strongly influenced by both FMPs and sampling date. The results from nonmetric multidimensional scaling (NMDS) ordination revealed distinct patterns of bacterial and fungal successions over time in leaf litter. We demonstrated that FMPs and sampling dates can influence a range of factors, including leaf litter quality, microbial macronutrients, and pH, which significantly correlate with microbial community successions.

[Effects of mixed decomposition of Populus simonii and other tree species leaf litters on soil properties in Loess Plateau].

PubMed

Li, Qian; Liu, Zeng-Wen; Du, Liang-Zhen

2012-03-01

In this study, the leaf litters of Populus simonii and other 11 tree species were put into soil separately or in mixture after grinding, and incubated in laboratory to analyze the effects of their decomposition on soil properties and the interactions between the litters decomposition. The decomposition of each kind of the leaf litters in soil increased the soil urease, dehydrogenase, and phosphatase activities and the soil organic matter and available N contents markedly, but had greater differences in the effects on the soil available P content and CEC. The decomposition of the leaf litters of Caragana microphylla and of Amorpha fruticosa showed obvious effects in improving soil properties. The decomposition of the mixed leaf litters of P. simonii and Pinus tabulaeformis, Platycladus orientalis, Robinia pseudoacacia, or Ulmus pumila showed interactive promotion effects on the abundance of soil microbes, and that of the mixed leaf litters of P. simonii and P. orientalis or C. microphylla showed interactive promotion effects on the soil organic matter, available P, and available K contents and soil CEC but interactive inhibition effects on the activities of most of the soil enzymes tested. The decomposition of the mixed leaf litters of P. simonii and Larix principis-rupprechtii showed interactive promotion effects on the activities of most of the soil enzymes and soil nutrient contents, while that of the mixed leaf litters of P. simonii and P. sylvestris var. mongolica showed interactive inhibition effects. Overall, the decomposition of the mixed leaf litters of P. simo- nii and U. pumila, P. tabulaeformis, L. principis-rupprechtii, or R. pseudoacacia could improve soil quality, but the mixed leaf litters of P. simonii and P. orientalis, C. microphylla, P. sylvestris var. mongolica, Hippophae rhamnoides, or A. fruticosa showed an interactive inhibition effect during their decomposition.

Influence of Litter Diversity on Dissolved Organic Matter Release and Soil Carbon Formation in a Mixed Beech Forest

PubMed Central

Scheibe, Andrea; Gleixner, Gerd

2014-01-01

We investigated the effect of leaf litter on below ground carbon export and soil carbon formation in order to understand how litter diversity affects carbon cycling in forest ecosystems. 13C labeled and unlabeled leaf litter of beech (Fagus sylvatica) and ash (Fraxinus excelsior), characterized by low and high decomposability, were used in a litter exchange experiment in the Hainich National Park (Thuringia, Germany). Litter was added in pure and mixed treatments with either beech or ash labeled with 13C. We collected soil water in 5 cm mineral soil depth below each treatment biweekly and determined dissolved organic carbon (DOC), δ13C values and anion contents. In addition, we measured carbon concentrations and δ13C values in the organic and mineral soil (collected in 1 cm increments) up to 5 cm soil depth at the end of the experiment. Litter-derived C contributes less than 1% to dissolved organic matter (DOM) collected in 5 cm mineral soil depth. Better decomposable ash litter released significantly more (0.50±0.17%) litter carbon than beech litter (0.17±0.07%). All soil layers held in total around 30% of litter-derived carbon, indicating the large retention potential of litter-derived C in the top soil. Interestingly, in mixed (ash and beech litter) treatments we did not find a higher contribution of better decomposable ash-derived carbon in DOM, O horizon or mineral soil. This suggest that the known selective decomposition of better decomposable litter by soil fauna has no or only minor effects on the release and formation of litter-derived DOM and soil organic matter. Overall our experiment showed that 1) litter-derived carbon is of low importance for dissolved organic carbon release and 2) litter of higher decomposability is faster decomposed, but litter diversity does not influence the carbon flow. PMID:25486628

Influence of litter diversity on dissolved organic matter release and soil carbon formation in a mixed beech forest.

PubMed

Scheibe, Andrea; Gleixner, Gerd

2014-01-01

We investigated the effect of leaf litter on below ground carbon export and soil carbon formation in order to understand how litter diversity affects carbon cycling in forest ecosystems. 13C labeled and unlabeled leaf litter of beech (Fagus sylvatica) and ash (Fraxinus excelsior), characterized by low and high decomposability, were used in a litter exchange experiment in the Hainich National Park (Thuringia, Germany). Litter was added in pure and mixed treatments with either beech or ash labeled with 13C. We collected soil water in 5 cm mineral soil depth below each treatment biweekly and determined dissolved organic carbon (DOC), δ13C values and anion contents. In addition, we measured carbon concentrations and δ13C values in the organic and mineral soil (collected in 1 cm increments) up to 5 cm soil depth at the end of the experiment. Litter-derived C contributes less than 1% to dissolved organic matter (DOM) collected in 5 cm mineral soil depth. Better decomposable ash litter released significantly more (0.50±0.17%) litter carbon than beech litter (0.17±0.07%). All soil layers held in total around 30% of litter-derived carbon, indicating the large retention potential of litter-derived C in the top soil. Interestingly, in mixed (ash and beech litter) treatments we did not find a higher contribution of better decomposable ash-derived carbon in DOM, O horizon or mineral soil. This suggest that the known selective decomposition of better decomposable litter by soil fauna has no or only minor effects on the release and formation of litter-derived DOM and soil organic matter. Overall our experiment showed that 1) litter-derived carbon is of low importance for dissolved organic carbon release and 2) litter of higher decomposability is faster decomposed, but litter diversity does not influence the carbon flow.

Potential energy expenditure by litter-roosting bats associated with temperature under leaf litter during winter

Treesearch

Roger W. Perry

2013-01-01

In temperate portions of North America, some bats that remain active during winter undergo short periods of hibernation below leaf litter on the forest floor during episodes of below-freezing weather. These winter roosts may provide above-freezing conditions, but the thermal conditions under leaf litter are unclear. Further, little is known of the relationship between...

Effect of elevated atmospheric CO2 concentration on growth and leaf litter decomposition of Quercus acutissima and Fraxinus rhynchophylla

PubMed Central

Cha, Sangsub; Chae, Hee-Myung; Lee, Sang-Hoon; Shim, Jae-Kuk

2017-01-01

The atmospheric carbon dioxide (CO2) level is expected to increase substantially, which may change the global climate and carbon dynamics in ecosystems. We examined the effects of an elevated atmospheric CO2 level on the growth of Quercus acutissima and Fraxinus rhynchophylla seedlings. We investigated changes in the chemical composition of leaf litter, as well as litter decomposition. Q. acutissima and F. rhynchophylla did not show differences in dry weight between ambient CO2 and enriched CO2 treatments, but they exhibited different patterns of carbon allocation, namely, lower shoot/root ratio (S/R) and decreased specific leaf area (SLA) under CO2-enriched conditions. The elevated CO2 concentration significantly reduced the nitrogen concentration in leaf litter while increasing lignin concentrations and carbon/nitrogen (C/N) and lignin/N ratios. The microbial biomass associated with decomposing Q. acutissima leaf litter was suppressed in CO2 enrichment chambers, while that of F. rhynchophylla was not. The leaf litter of Q. acutissima from the CO2-enriched chambers, in contrast with F. rhynchophylla, contained much lower nutrient concentrations than that of the litter in the ambient air chambers. Consequently, poorer litter quality suppressed decomposition. PMID:28182638

Effect of elevated atmospheric CO2 concentration on growth and leaf litter decomposition of Quercus acutissima and Fraxinus rhynchophylla.

PubMed

Cha, Sangsub; Chae, Hee-Myung; Lee, Sang-Hoon; Shim, Jae-Kuk

2017-01-01

The atmospheric carbon dioxide (CO2) level is expected to increase substantially, which may change the global climate and carbon dynamics in ecosystems. We examined the effects of an elevated atmospheric CO2 level on the growth of Quercus acutissima and Fraxinus rhynchophylla seedlings. We investigated changes in the chemical composition of leaf litter, as well as litter decomposition. Q. acutissima and F. rhynchophylla did not show differences in dry weight between ambient CO2 and enriched CO2 treatments, but they exhibited different patterns of carbon allocation, namely, lower shoot/root ratio (S/R) and decreased specific leaf area (SLA) under CO2-enriched conditions. The elevated CO2 concentration significantly reduced the nitrogen concentration in leaf litter while increasing lignin concentrations and carbon/nitrogen (C/N) and lignin/N ratios. The microbial biomass associated with decomposing Q. acutissima leaf litter was suppressed in CO2 enrichment chambers, while that of F. rhynchophylla was not. The leaf litter of Q. acutissima from the CO2-enriched chambers, in contrast with F. rhynchophylla, contained much lower nutrient concentrations than that of the litter in the ambient air chambers. Consequently, poorer litter quality suppressed decomposition.

Rain forest nutrient cycling and productivity in response to large-scale litter manipulation.

PubMed

Wood, Tana E; Lawrence, Deborah; Clark, Deborah A; Chazdon, Robin L

2009-01-01

Litter-induced pulses of nutrient availability could play an important role in the productivity and nutrient cycling of forested ecosystems, especially tropical forests. Tropical forests experience such pulses as a result of wet-dry seasonality and during major climatic events, such as strong El Niños. We hypothesized that (1) an increase in the quantity and quality of litter inputs would stimulate leaf litter production, woody growth, and leaf litter nutrient cycling, and (2) the timing and magnitude of this response would be influenced by soil fertility and forest age. To test these hypotheses in a Costa Rican wet tropical forest, we established a large-scale litter manipulation experiment in two secondary forest sites and four old-growth forest sites of differing soil fertility. In replicated plots at each site, leaves and twigs (< 2 cm diameter) were removed from a 400-m2 area and added to an adjacent 100-m2 area. This transfer was the equivalent of adding 5-25 kg/ha of organic P to the forest floor. We analyzed leaf litter mass, [N] and [P], and N and P inputs for addition, removal, and control plots over a two-year period. We also evaluated basal area increment of trees in removal and addition plots. There was no response of forest productivity or nutrient cycling to litter removal; however, litter addition significantly increased leaf litter production and N and P inputs 4-5 months following litter application. Litter production increased as much as 92%, and P and N inputs as much as 85% and 156%, respectively. In contrast, litter manipulation had no significant effect on woody growth. The increase in leaf litter production and N and P inputs were significantly positively related to the total P that was applied in litter form. Neither litter treatment nor forest type influenced the temporal pattern of any of the variables measured. Thus, environmental factors such as rainfall drive temporal variability in litter and nutrient inputs, while nutrient release from decomposing litter influences the magnitude. Seasonal or annual variation in leaf litter mass, such as occurs in strong El Niño events, could positively affect leaf litter nutrient cycling and forest productivity, indicating an ability of tropical trees to rapidly respond to increased nutrient availability.

Leaf litter breakdown of native and exotic tree species in two Hawaiian streams that differ in flow

Treesearch

Megan Roberts; Ayron M. Strauch; Tracy Wiegner; Richard A. Mackenzie

2016-01-01

Riparian leaf litter is a major source of allochthonous organic material to temperate and tropical streams, promoting primary and secondary productivity in lotic and nearshore habitats. In tropical island streams, where native leaf-shredding macroinvertebrates are absent, physical fragmentation from stream flow is an important factor affecting leaf litter breakdown and...

[Relationship between leaf litter decomposition and colonization of benthic macroinvertebrates during early frost period in a headwater stream in the Changbai Mountains, Northeast China].

PubMed

Wang, Lu; Yang, Hai Jun; Li, Ling; Nan, Xiao Fei; Zhang, Zhen Xing; Li, Kun

2017-11-01

Annually, about 70% of the streams in the Changbai Mountains are frosted during November to April, with manifest seasonal freeze-thaw characters. By using monoculture and mixing leaf litters of Tilia amurensis, Acer mono and Quecus mongolica, this research attempted to disentangle the relationship between leaf litter decomposition and colonization of macroinvertebrates in the stream during early frost period. A 35-day investigation was carried out in a headwater stream of the Changbai Mountains. Nylon bags with two hole sizes (5 mm and 0.3 mm) were used to examine decomposition of the litters. The results showed that the mass losses were significantly different among the three kinds of leaf litters in monoculture, whose decomposition rates descended as A. mono, T. amurensis, and Q. mongolica, however, there existed no significant difference among the litter mixing. Mass losses in both mesh bags all showed little difference, except T. amurensis and the mixed litters. Litter mixing effects occurred in the coarse mesh bags with A. mono and Q. mongolica, but no mixture effects for others. Community structures of the macroinvertebrates colonizing in the litter bags differed with each other, but shredders' density had no significant difference among the three litters, and the mixing effects on shredders were poor. Our results implied that microbes play the major decomposers of leaf litters, and macroinvertebrates contribute little to the decomposition in the early frost period. Despite shredder's density is lower, they determine the mixing effects of litters. Macroinvertebrates are selective to food and habitats, however, due to the short term colonizing, and the influence of leaf litters on shredders is still unsure. Our results might contribute to understanding the cold season ecological processes and related management issues of headwater stream ecosystem.

Variations in the methane budget over the last two millennia

NASA Astrophysics Data System (ADS)

Derendorp, L.

2012-06-01

Leaf litter is available at the Earth’s surface in large quantities. During the decomposition of leaf litter, volatile compounds can be released into the atmosphere, where they potentially influence local air quality, atmospheric chemistry or the global climate. In this thesis the focus was on the emission of C2-C5 hydrocarbons, molecular hydrogen (H2), carbon monoxide (CO) and methyl chloride (CH3Cl) from leaf litter and the factors that control the emissions were investigated. For different plant species, the emission rates of several C2-C5 hydrocarbons increased with temperature between 20 and 100°C according to the Arrhenius relation. When leaf litter was irradiated with UV, the emission increased linearly with the intensity of the UV. UVB radiation was more efficient in the generation of hydrocarbons from leaf litter than UVA. A simple upscaling showed that C2-C5 hydrocarbon emissions from leaf litter are likely insignificant for their global budgets, but may have a small influence on atmospheric chemistry on the local scale. Senescent and dead plant material releases carbon monoxide (CO), methane and larger hydrocarbons upon heating or irradiation with UV, but emissions of hydrogen (H2) have not been reported. In this study, H2 was released from leaf litter of Sequoiadendron giganteum in detectable amounts at temperatures above 45°C, whereas CO was also emitted at ambient temperature. Leaf litter has been identified as a potentially important source of CH3Cl. However, the factors controlling the emissions are unclear. Laboratory experiments have been performed in which CH3Cl emissions were measured from leaf litter of different plant species. For each investigated plant species, the CH3Cl emission rate strongly increased with temperature according to the Arrhenius relation. However, at constant temperature, large differences between different plants were observed. Therefore, CH3Cl emissions were measured from halophyte leaf litter with a varying chloride content, but no significant correlation between the CH3Cl emission rate and the chloride content of the plant material was observed. A limited set of field experiments was performed in which CH3Cl emissions were measured. Leaf litter emitted CH3Cl, but only in periods with fresh leaf litter fall. Outside these periods, the flux from leaf litter was zero or even slightly negative. The CH3Cl emission rate increased with temperature, but the temperature increase did not follow the Arrhenius relation as was observed in the laboratory experiments. The global importance of leaf litter as a source of CH3Cl was investigated using the global chemistry transport model TM5. Forward simulations with different emission scenarios indicated that at station Trinidad Head (mid-latitudes of North America), a substantial seasonal emission from leaf litter was required to match the measured CH3Cl mixing ratios at this station. Inversions performed with the TM4-4D-Var system indicated that the main CH3Cl sources were located in the Tropics, whereas the mid- and high latitudes were only a minor source. Sensitivity studies performed to investigate the robustness of the optimized emissions indicated that more than 90% of the global net emissions was located in the Tropics.

Effects of anthropogenic heavy metal contamination on litter decomposition in streams - A meta-analysis.

PubMed

Ferreira, Verónica; Koricheva, Julia; Duarte, Sofia; Niyogi, Dev K; Guérold, François

2016-03-01

Many streams worldwide are affected by heavy metal contamination, mostly due to past and present mining activities. Here we present a meta-analysis of 38 studies (reporting 133 cases) published between 1978 and 2014 that reported the effects of heavy metal contamination on the decomposition of terrestrial litter in running waters. Overall, heavy metal contamination significantly inhibited litter decomposition. The effect was stronger for laboratory than for field studies, likely due to better control of confounding variables in the former, antagonistic interactions between metals and other environmental variables in the latter or differences in metal identity and concentration between studies. For laboratory studies, only copper + zinc mixtures significantly inhibited litter decomposition, while no significant effects were found for silver, aluminum, cadmium or zinc considered individually. For field studies, coal and metal mine drainage strongly inhibited litter decomposition, while drainage from motorways had no significant effects. The effect of coal mine drainage did not depend on drainage pH. Coal mine drainage negatively affected leaf litter decomposition independently of leaf litter identity; no significant effect was found for wood decomposition, but sample size was low. Considering metal mine drainage, arsenic mines had a stronger negative effect on leaf litter decomposition than gold or pyrite mines. Metal mine drainage significantly inhibited leaf litter decomposition driven by both microbes and invertebrates, independently of leaf litter identity; no significant effect was found for microbially driven decomposition, but sample size was low. Overall, mine drainage negatively affects leaf litter decomposition, likely through negative effects on invertebrates. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mercury in leaf litter in typical suburban and urban broadleaf forests in China.

PubMed

Niu, Zhenchuan; Zhang, Xiaoshan; Wang, Zhangwei; Ci, Zhijia

2011-01-01

To study the role of leaf litter in the mercury (Hg) cycle in suburban broadleaf forests and the distribution of Hg in urban forests, we collected leaf litter and soil from suburban evergreen and deciduous broadleaf forests and from urban forests in Beijing. The Hg concentrations in leaf litter from the suburban forests varied from 8.3 to 205.0 ng/g, with an average (avg) of (49.7 +/- 36.9) ng/g. The average Hg concentration in evergreen broadleaf forest leaf litter (50.8 + 39.4) ng/g was higher than that in deciduous broadleaf forest leaf litter (25.8 +/- 10.1) ng/g. The estimated Hg fluxes of leaf litter in suburban evergreen and deciduous broadleaf forests were 179.0 and 83.7 mg/(ha x yr), respectively. The Hg concentration in organic horizons (O horizons) ((263.1 +/- 237.2) ng/g) was higher than that in eluvial horizons (A horizons) ((83.9 +/- 52.0) ng/g). These results indicated that leaf litterfall plays an important role in transporting atmospheric mercury to soil in suburban forests. For urban forests in Beijing, the Hg concentrations in leaf litter ranged from 8.8-119.0 (avg 28.1 +/- 16.6) ng/g, with higher concentrations at urban sites than at suburban sites for each tree. The Hg concentrations in surface soil in Beijing were 32.0-25300.0 ng/g and increased from suburban sites to urban sites, with the highest value from Jingshan (JS) Park at the centre of Beijing. Therefore, the distribution of Hg in Beijing urban forests appeared to be strongly influenced by anthropogenic activities.

Microbial decomposition is highly sensitive to leaf litter emersion in a permanent temperate stream.

PubMed

Mora-Gómez, Juanita; Duarte, Sofia; Cássio, Fernanda; Pascoal, Cláudia; Romaní, Anna M

2018-04-15

Drought frequency and intensity in some temperate regions are forecasted to increase under the ongoing global change, which might expose permanent streams to intermittence and have severe repercussions on stream communities and ecosystem processes. In this study, we investigated the effect of drought duration on microbial decomposition of Populus nigra leaf litter in a temperate permanent stream (Oliveira, NW Portugal). Specifically, we measured the response of the structural (assemblage composition, bacterial and fungal biomass) and functional (leaf litter decomposition, extracellular enzyme activities (EEA), and fungal sporulation) parameters of fungal and bacterial communities on leaf litter exposed to emersion during different time periods (7, 14 and 21d). Emersion time affected microbial assemblages and litter decomposition, but the response differed among variables. Leaf decomposition rates and the activity of β-glucosidase, cellobiohydrolase and phosphatase were gradually reduced with increasing emersion time, while β-xylosidase reduction was similar when emersion last for 7 or more days, and the phenol oxidase reduction was similar at 14 and 21days of leaf emersion. Microbial biomass and fungal sporulation were reduced after 21days of emersion. The structure of microbial assemblages was affected by the duration of the emersion period. The shifts in fungal assemblages were correlated with a decreased microbial capacity to degrade lignin and hemicellulose in leaf litter exposed to emersion. Additionally, some resilience was observed in leaf litter mass loss, bacterial biomass, some enzyme activities and structure of fungal assemblages. Our study shows that drought can strongly alter structural and functional aspects of microbial decomposers. Therefore, the exposure of leaf litter to increasing emersion periods in temperate streams is expected to affect decomposer communities and overall decomposition of plant material by decelerating carbon cycling in streams. Copyright © 2017 Elsevier B.V. All rights reserved.

Dynamics of leaf litter humidity, depth and quantity: two restoration strategies failed to mimic ground microhabitat conditions of a low montane and premontane forest in Costa Rica.

PubMed

Barrientos, Zaidett

2012-09-01

Little is known about how restoration strategies affect aspects like leaf litter's quantity, depth and humidity. I analyzed leaf litter's quantity, depth and humidity yearly patterns in a primary tropical lower montane wet forest and two restored areas: a 15 year old secondary forest (unassisted restoration) and a 40 year old Cupressus lusitanica plantation (natural understory). The three habitats are located in the Rio Macho Forest Reserve, Costa Rica. Twenty litter samples were taken every three months (April 2009-April 2010) in each habitat; humidity was measured in 439g samples (average), depth and quantity were measured in five points inside 50x50cm plots. None of the restoration strategies reproduced the primary forest leaf litter humidity, depth and quantity yearly patterns. Primary forest leaf litter humidity was higher and more stable (mean=73.2), followed by secondary forest (mean=63.3) and cypress plantation (mean=52.9) (Kruskall-Wallis=77.93, n=232, p=0.00). In the primary (Kruskal-Wallis=31.63, n=78, p<0.001) and secondary (Kruskal-Wallis=11.79, n=75, p=0.008) forest litter accumulation was higher during April due to strong winds. In the primary forest (Kruskal-wallis=21.83, n=78, p<0.001) and the cypress plantation (Kruskal-wallis=39.99, n=80, p<0.001) leaf litter depth was shallow in October because heavy rains compacted it. Depth patterns were different from quantity patterns and described the leaf litter's structure in different ecosystems though the year. September 01.

Foliar pH as a new plant trait: can it explain variation in foliar chemistry and carbon cycling processes among subarctic plant species and types?

PubMed

Cornelissen, J H C; Quested, H M; van Logtestijn, R S P; Pérez-Harguindeguy, N; Gwynn-Jones, D; Díaz, S; Callaghan, T V; Press, M C; Aerts, R

2006-03-01

Plant traits have become popular as predictors of interspecific variation in important ecosystem properties and processes. Here we introduce foliar pH as a possible new plant trait, and tested whether (1) green leaf pH or leaf litter pH correlates with biochemical and structural foliar traits that are linked to biogeochemical cycling; (2) there is consistent variation in green leaf pH or leaf litter pH among plant types as defined by nutrient uptake mode and higher taxonomy; (3) green leaf pH can predict a significant proportion of variation in leaf digestibility among plant species and types; (4) leaf litter pH can predict a significant proportion of variation in leaf litter decomposability among plant species and types. We found some evidence in support of all four hypotheses for a wide range of species in a subarctic flora, although cryptogams (fern allies and a moss) tended to weaken the patterns by showing relatively poor leaf digestibility or litter decomposability at a given pH. Among seed plant species, green leaf pH itself explained only up to a third of the interspecific variation in leaf digestibility and leaf litter up to a quarter of the interspecific variation in leaf litter decomposability. However, foliar pH substantially improved the power of foliar lignin and/or cellulose concentrations as predictors of these processes when added to regression models as a second variable. When species were aggregated into plant types as defined by higher taxonomy and nutrient uptake mode, green-specific leaf area was a more powerful predictor of digestibility or decomposability than any of the biochemical traits including pH. The usefulness of foliar pH as a new predictive trait, whether or not in combination with other traits, remains to be tested across more plant species, types and biomes, and also in relation to other plant or ecosystem traits and processes.

Evaluation of a method for removing cesium and reducing the volume of leaf litter from broad-leaved trees contaminated by the Fukushima Daiichi nuclear accident during the Great East Japan Earthquake.

PubMed

Harada, Shigeki; Yanagisawa, Mitsunori

2017-04-01

The town of Marumori in southern Miyagi Prefecture borders on Fukushima Prefecture, and following the accident at the Fukushima Daiichi nuclear power plant, there were concerns about cesium deposition in forested areas. One of the authors of this paper has continually surveyed leaf litter from the forested areas. As leaf litter may be a source of cesium contamination from the forest to downstream areas, we considered a simplified version of wet oxidation, a method previously presented by one of the authors of this study, as a technology to reduce leaf litter weight and cesium concentration, separating radioactive nuclides from non-radioactive ones, in leaf litter. We tested our method in three experiments. Experiment 1 used new leaf litter (232 Bq/kg) from the surface of a small stream at the forest edge nearby an area with air dose level higher than the national standard threshold of 0.23 μSv/h for the implementation of governmental decontamination works. Experiment 2 applied wet oxidation to older leaf litter (705 Bq/kg) harvested from a pasture nearby the stream mentioned above. We also used the same leaf litter in experiment 3 for a cesium release tests using pure water. In experiment 1 and 2 we treated leaf litter with a sodium hypochlorite solution, optimizing sodium hypochlorite concentration and reaction temperature. We measured a 50-60% decrease in the leaf litter weight and a 60% decrease in the cesium concentration. Moreover, we also measured the amount of cesium washout. The cesium budget of experiment 1 showed no cesium gasification (wet oxidation avoids airborne cesium as this element is prone to be volatile at 600 °C), and that high sodium hypochlorite concentration and high temperature had a strong positive effect on leaf litter volume reduction and cesium decontamination. Experiment 2 confirmed the reproducibility of these results in leaves with different cesium concentration and harvested in different conditions. We could also explain the mechanism behind leaf litter weight and cesium concentration reduction. Experiment 3 helped us to investigate the effects of the matter present on the surface of the water and the contribution of water soluble cesium. Concurrent experiments on changes in leaf litter chemical composition confirmed that our modified wet oxidation method had an effect on the removal of acid-insoluble lignin. Removal of lignin, a refractory component, might allow for a better utilization of the residue left after implementation of the proposed simplified wet oxidation. Thus, real wastes could be smaller than the residues. Together with the observed smaller cesium concentration in the residue, the proposed method in this study is expected to contribute to mitigate the risk due to the fallen leaves containing cesium. Copyright © 2017 Elsevier Ltd. All rights reserved.

The partitioning of litter carbon during litter decomposition under different rainfall patterns: a laboratory study

NASA Astrophysics Data System (ADS)

Yang, X.; Szlavecz, K. A.; Langley, J. A.; Pitz, S.; Chang, C. H.

2017-12-01

Quantifying litter C into different C fluxes during litter decomposition is necessary to understand carbon cycling under changing climatic conditions. Rainfall patterns are predicted to change in the future, and their effects on the fate of litter carbon are poorly understood. Soils from deciduous forests in Smithsonian Environmental Research Center (SERC) in Maryland, USA were collected to reconstruct soil columns in the lab. 13C labeled tulip poplar leaf litter was used to trace carbon during litter decomposition. Top 1% and the mean of 15-minute historical precipitation data from nearby weather stations were considered as extreme and control rainfall intensity, respectively. Both intensity and frequency of rainfall were manipulated, while the total amount was kept constant. A pulse of CO2 efflux was detected right after each rainfall event in the soil columns with leaf litter. After the first event, CO2 efflux of the control rainfall treatment soils increased to threefold of the CO2 efflux before rain event and that of the extreme treatment soils increased to fivefold. However, in soils without leaf litter, CO2 efflux was suppressed right after rainfall events. After each rainfall event, the leaf litter contribution to CO2 efflux first showed an increase, decreased sharply in the following two days, and then stayed relatively constant. In soil columns with leaf litter, the order of cumulative CO2 efflux was control > extreme > intermediate. The order of cumulative CO2 efflux in the bare soil treatment was extreme > intermediate > control. The order of volume of leachate from different treatments was extreme > intermediate > control. Our initial results suggest that more intense rainfall events result in larger pulses of CO2, which is rarely measured in the field. Additionally, soils with and without leaf litter respond differently to precipitation events. This is important to consider in temperate regions where leaf litter cover changes throughout the year. Including the rainfall pattern as a parameter to the partitioning of litter carbon could help better project soil carbon cycling in the Mid-Atlantic region.

Evaluation of Methane from Sisal Leaf Residue and Palash Leaf Litter

NASA Astrophysics Data System (ADS)

Arisutha, S.; Baredar, P.; Deshpande, D. M.; Suresh, S.

2014-12-01

The aim of this study is to evaluate methane production from sisal leaf residue and palash leaf litter mixed with different bulky materials such as vegetable market waste, hostel kitchen waste and digested biogas slurry in a laboratory scale anaerobic reactor. The mixture was prepared with 1:1 proportion. Maximum methane content of 320 ml/day was observed in the case of sisal leaf residue mixed with vegetable market waste as the feed. Methane content was minimum (47 ml/day), when palash leaf litter was used as feed. This was due to the increased content of lignin and polyphenol in the feedstock which were of complex structure and did not get degraded directly by microorganisms. Sisal leaf residue mixtures also showed highest content of volatile fatty acids (VFAs) as compared to palash leaf litter mixtures. It was observed that VFA concentration in the digester first increased, reached maximum (when pH was minimum) and then decreased.

STUDY OF SOIL AND LEAF LITTER MICROBIAL FATTY ACID PROFILES IN TABONUCO FOREST IN THE LUQUILLO EXPERIMENTAL FOREST IN PUERTO RICO

EPA Science Inventory

The results of this study suggests that there are two significantly distinct microbial communities in the leaf litter and soil components of this tropical forest. Fungi are more abundant in the leaf litter while bacteria are more abundant in the soil.

Increasing shrub abundance and N addition in Arctic tundra affect leaf and root litter decomposition differently

NASA Astrophysics Data System (ADS)

McLaren, J.; van de Weg, M. J.; Shaver, G. R.; Gough, L.

2013-12-01

Changes in global climate have resulted in a ';greening' of the Arctic as the abundance of deciduous shrub species increases. Consequently, not only the living plant community, but also the litter composition changes, which in turn can affect carbon turnover patterns in the Arctic. We examined effects of changing litter composition (both root and leaf litter) on decomposition rates with a litter bag study, and specifically focused on the impact of deciduous shrub Betula nana litter on litter decomposition from two evergreen shrubs (Ledum palustre, and Vaccinium vitis-idaea) and one graminoid (Eriophorum vaginatum) species. Additionally, we investigated how decomposition was affected by nutrient availability by placing the litterbags in an ambient and a fertilized moist acidic tundra environment. Measurements were carried out seasonally over 2 years (after snow melt, mid-growing season, end growing season). We measured litter mass loss over time, as well as the respiration rates (standardized for temperature and moisture) and temperature sensitivity of litter respiration at the time of harvesting the litter bags. For leaves, Betula litter decomposed faster than the other three species, with Eriophorum leaves decomposing the slowest. This pattern was observed for both mass loss and litter respiration rates, although the differences in respiration became smaller over time. Surprisingly, combining Betula with any other species resulted in slower overall weight loss rates than would be predicted based on monoculture weight loss rates. This contrasted with litter respiration at the time of sampling, which showed a positive mixing effect of adding Betula leaf liter to the other species. Apparently, during the first winter months (September - May) Betula litter decomposition is negatively affected by mixing the species and this legacy can still be observed in the total mass loss results later in the year. For root litter there were fewer effects of species identity on root decomposition rates; only Ledum roots decomposed slower than the other three species and the overall root litter respiration rates increased with the duration of the experiment (in contrast to leaf liter respiration). A fertilized environment had no effect on overall weight loss of the leaf or root litter within the time of our study, but leaf and root litter respiration rates were significantly larger at the end of the study in the fertilized tundra.The temperature sensitivity of leaf respiration was significantly lower for leaf litter respiration than root liter respiration after fist snow melt, but this difference disappeared throughout the first growing season and neither was influenced by species composition or fertilization with N+P. Overall, our results suggest that as arctic vegetation shifts towards shrub-dominated tundra, both species composition and seasonally dependent processes will determine effects of changing vegetation types on carbon turnover in arctic ecosystems.

Ecosystem and decomposer effects on litter dynamics along an old field to old-growth forest successional gradient

NASA Astrophysics Data System (ADS)

Mayer, Paul M.

2008-03-01

Identifying the biotic (e.g. decomposers, vegetation) and abiotic (e.g. temperature, moisture) mechanisms controlling litter decomposition is key to understanding ecosystem function, especially where variation in ecosystem structure due to successional processes may alter the strength of these mechanisms. To identify these controls and feedbacks, I measured mass loss and N flux in herbaceous, leaf, and wood litter along a successional gradient of ecosystem types (old field, transition forest, old-growth forest) while manipulating detritivore access to litter. Ecosystem type, litter type, and decomposers contributed directly and interactively to decomposition. Litter mass loss and N accumulation was higher while litter C:N remained lower in old-growth forests than in either old fields or transition forest. Old-growth forests influenced litter dynamics via microclimate (coolest and wettest) but also, apparently, through a decomposer community adapted to consuming the large standing stocks of leaf litter, as indicated by rapid leaf litter loss. In all ecosystem types, mass loss of herbaceous litter was greater than leaf litter which, in turn was greater than wood. However, net N loss from wood litter was faster than expected, suggesting localized N flux effects of wood litter. Restricting detritivore access to litter reduced litter mass loss and slowed the accumulation of N in litter, suggesting that macro-detritivores affect both physical and chemical characteristics of litter through selective grazing. These data suggest that the distinctive litter loss rates and efficient N cycling observed in old-growth forest ecosystems are not likely to be realized soon after old fields are restored to forested ecosystems.

The effect of leaf litter cover on surface runoff and soil erosion in Northern China.

PubMed

Li, Xiang; Niu, Jianzhi; Xie, Baoyuan

2014-01-01

The role of leaf litter in hydrological processes and soil erosion of forest ecosystems is poorly understood. A field experiment was conducted under simulated rainfall in runoff plots with a slope of 10%. Two common types of litter in North China (from Quercus variabilis, representing broadleaf litter, and Pinus tabulaeformis, representing needle leaf litter), four amounts of litter, and five rainfall intensities were tested. Results revealed that the litter reduced runoff and delayed the beginning of runoff, but significantly reduced soil loss (p<0.05). Average runoff yield was 29.5% and 31.3% less than bare-soil plot, and for Q. variabilis and P. tabulaeformis, respectively, and average sediment yield was 85.1% and 79.9% lower. Rainfall intensity significantly affected runoff (R = 0.99, p<0.05), and the efficiency in runoff reduction by litter decreased considerably. Runoff yield and the runoff coefficient increased dramatically by 72.9 and 5.4 times, respectively. The period of time before runoff appeared decreased approximately 96.7% when rainfall intensity increased from 5.7 to 75.6 mm h-1. Broadleaf and needle leaf litter showed similarly relevant effects on runoff and soil erosion control, since no significant differences (p≤0.05) were observed in runoff and sediment variables between two litter-covered plots. In contrast, litter mass was probably not a main factor in determining runoff and sediment because a significant correlation was found only with sediment in Q. variabilis litter plot. Finally, runoff yield was significantly correlated (p<0.05) with sediment yield. These results suggest that the protective role of leaf litter in runoff and erosion processes was crucial, and both rainfall intensity and litter characteristics had an impact on these processes.

The Effect of Leaf Litter Cover on Surface Runoff and Soil Erosion in Northern China

PubMed Central

Li, Xiang; Niu, Jianzhi; Xie, Baoyuan

2014-01-01

The role of leaf litter in hydrological processes and soil erosion of forest ecosystems is poorly understood. A field experiment was conducted under simulated rainfall in runoff plots with a slope of 10%. Two common types of litter in North China (from Quercus variabilis, representing broadleaf litter, and Pinus tabulaeformis, representing needle leaf litter), four amounts of litter, and five rainfall intensities were tested. Results revealed that the litter reduced runoff and delayed the beginning of runoff, but significantly reduced soil loss (p<0.05). Average runoff yield was 29.5% and 31.3% less than bare-soil plot, and for Q. variabilis and P. tabulaeformis, respectively, and average sediment yield was 85.1% and 79.9% lower. Rainfall intensity significantly affected runoff (R = 0.99, p<0.05), and the efficiency in runoff reduction by litter decreased considerably. Runoff yield and the runoff coefficient increased dramatically by 72.9 and 5.4 times, respectively. The period of time before runoff appeared decreased approximately 96.7% when rainfall intensity increased from 5.7 to 75.6 mm h−1. Broadleaf and needle leaf litter showed similarly relevant effects on runoff and soil erosion control, since no significant differences (p≤0.05) were observed in runoff and sediment variables between two litter-covered plots. In contrast, litter mass was probably not a main factor in determining runoff and sediment because a significant correlation was found only with sediment in Q. variabilis litter plot. Finally, runoff yield was significantly correlated (p<0.05) with sediment yield. These results suggest that the protective role of leaf litter in runoff and erosion processes was crucial, and both rainfall intensity and litter characteristics had an impact on these processes. PMID:25232858

Experimental evidence that the Ornstein-Uhlenbeck model best describes the evolution of leaf litter decomposability.

PubMed

Pan, Xu; Cornelissen, Johannes H C; Zhao, Wei-Wei; Liu, Guo-Fang; Hu, Yu-Kun; Prinzing, Andreas; Dong, Ming; Cornwell, William K

2014-09-01

Leaf litter decomposability is an important effect trait for ecosystem functioning. However, it is unknown how this effect trait evolved through plant history as a leaf 'afterlife' integrator of the evolution of multiple underlying traits upon which adaptive selection must have acted. Did decomposability evolve in a Brownian fashion without any constraints? Was evolution rapid at first and then slowed? Or was there an underlying mean-reverting process that makes the evolution of extreme trait values unlikely? Here, we test the hypothesis that the evolution of decomposability has undergone certain mean-reverting forces due to strong constraints and trade-offs in the leaf traits that have afterlife effects on litter quality to decomposers. In order to test this, we examined the leaf litter decomposability and seven key leaf traits of 48 tree species in the temperate area of China and fitted them to three evolutionary models: Brownian motion model (BM), Early burst model (EB), and Ornstein-Uhlenbeck model (OU). The OU model, which does not allow unlimited trait divergence through time, was the best fit model for leaf litter decomposability and all seven leaf traits. These results support the hypothesis that neither decomposability nor the underlying traits has been able to diverge toward progressively extreme values through evolutionary time. These results have reinforced our understanding of the relationships between leaf litter decomposability and leaf traits in an evolutionary perspective and may be a helpful step toward reconstructing deep-time carbon cycling based on taxonomic composition with more confidence.

The second wave of earthworm invasion: soil organic matter dynamics from the stable isotope perspective

NASA Astrophysics Data System (ADS)

Chang, C.; Szlavecz, K. A.; Bernard, M.; Pitz, S.

2013-12-01

Through transformation of plant litter into soil organic matter (SOM) and translocation of ingested organic material among different soil depths, soil organisms, especially earthworms, are one of the major factors affecting SOM dynamics. In North America temperate soil, historical human activity has lead to invasion of European earthworms into habitats that were previously earthworm-free or inhabited only by native species. By consuming leaf litter and SOM, burrowing, and casting, invasive earthworms have been known for reducing the understory vegetation and leaf litter layer while increasing the thickness of organic soil, causing changes in the soil habitat and the distribution of SOM. Recently, another group of invasive earthworm, namely Amynthas from Asia, has been reported invading habitats already dominated by European species, causing a 'second wave of invasion' where the soil ecosystem, already modified by European species, is going through another transition. The mechanisms through which these functionally (ecologically) different species affect C and N transformation could be better understood by tracing the carbon and nitrogen derived from 13C- and 15N-labeled leaf litter into earthworm tissues and SOM. The objective of this study is to understand how earthworm species that differ ecologically, including the Asian Amynthas, interact with each other and how these interactions affect SOM dynamics. We hypothesized that 1) species feeding on different food resources will have different isotopic signature and their tissue 13C and 15N values will change due to facilitation or interspecific competition on food resources, and 2) the short-term fate of litter-derived carbon differs depending on the presence or absence of different earthworm species. These hypotheses were tested by field sampling and lab mesocosm experiments using 13C and 15N double-enriched Tulip Poplar leaf litter (mean 13C = 124‰, mean 15N = 1667‰) produced from tree saplings growing in an airtight chamber. Stable isotope mass balance calculation is used to estimate the recovery of litter-derived carbon from three pools (earthworm tissue, SOM, remaining litter), the loss of litter-derived carbon through soil respiration, and the contribution of different carbon sources to soil CO2 efflux in different earthworm treatments. Our results show that earthworm species recognized as 'soil feeders' have 13C and 15N values that are 1.2‰ and 3.8‰ higher than those of 'litter feeders', and 15N also differ significantly amount different soil feeders, suggesting different food resource usage even within the same functional group. There are strong species effects on both leaf litter disappearance rate and CO2 efflux rate, both being high when Amynthas earthworms are present. Our results suggest that changing earthworm species composition leads to changing resource use, which alters the fate of organic carbon in the forest floor and soil and could potentially affect long-term SOM dynamics in temperate forests.

Galling by Rhopalomyia solidaginis alters Solidago altissima architecture and litter nutrient dynamics in an old-field ecosystem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crutsinger, Greg; Habenicht, Melissa N; Classen, Aimee T

2008-01-01

Plant-insect interactions can alter ecosystem processes, especially if the insects modify plant architecture, quality, or the quantity of leaf litter inputs. In this study, we investigated the interactions between the gall midge Rhopalomyia solidaginis and tall goldenrod, Solidago altissima, to quantify the degree to which the midge alters plant architecture and how the galls affect rates of litter decomposition and nutrient release in an old-field ecosystem. R. solidaginis commonly leads to the formation of a distinct apical rosette gall on S. altissima and approximately 15% of the ramets in a S. altissima patch were galled (range: 3-34%). Aboveground biomass ofmore » galled ramets was 60% higher and the leaf area density was four times greater on galled leaf tissue relative to the portions of the plant that were not affected by the gall. Overall decomposition rate constants did not differ between galled and ungalled leaf litter. However, leaf-litter mass loss was lower in galled litter relative to ungalled litter, which was likely driven by modest differences in initial litter chemistry; this effect diminished after 12 weeks of decomposition in the field. The proportion of N remaining was always higher in galled litter than in ungalled litter at each collection date indicating differential release of nitrogen in galled leaf litter. Several studies have shown that plant-insect interactions on woody species can alter ecosystem processes by affecting the quality or quantity of litter inputs. Our results illustrate how plant-insect interactions in an herbaceous species can affect ecosystem processes by altering the quality and quantity of litter inputs. Given that S. altissima dominates fields and roadsides and that R. solidaginis galls are highly abundant throughout eastern North America, these interactions are likely to be important for both the structure and function of old-field ecosystems.« less

Fate of leaf-litter N in forest and grassland along a pedo-climatic gradient in south-western Siberia: an in situ 15N-labelling experiment

NASA Astrophysics Data System (ADS)

Brédoire, Félix; Zeller, Bernd; Nikitich, Polina; Barsukov, Pavel A.; Rusalimova, Olga; Bakker, Mark R.; Legout, Arnaud; Bashuk, Alexander; Kayler, Zachary E.; Derrien, Delphine

2017-04-01

The suitability of Siberia for agriculture is expected to increase in the next decades due to strong and rapid climatic changes, but little is known on the environmental drivers of soil fertility there, especially nitrogen (N). Plant-available N is mainly derived from litter decomposition. South-western (SW) Siberia is located on the transition between several bioclimatic zones that are predicted to shift and extend along with climate change (steppe, forest-steppe, sub-taiga). The soils of this region are formed on a common loess deposit but they are submitted to different climatic conditions and vegetation cover. In the south of the region, typically in steppe/forest-steppe, soil freezes over winter because of a relatively shallow snow-pack, and water shortages are frequent in summer. In the north, typically in sub-taiga, the soil is barely frozen in winter due to a thick snow-pack and sufficient soil moisture in summer. In this study, we characterized the dynamics of leaf litter decomposition and the transfer of N from leaf litter to the soil and back to plants. Four sites were chosen along a climate gradient (temperature, precipitation and snow depth). At each site, we applied 15N-labelled leaf litter on the soil surface in experimental plots in an aspen (Populus tremula L.) forest and in a grassland. Twice a year during three years, we tracked the 15N derived from the decomposing labelled-litter in the organic layers, in the first 15 cm of the soil, and in above-ground vegetation. Soil temperature and moisture were monitored at a daily timestep over three years and soil water budgets were simulated (BILJOU model, Granier et al. 1999). We observed contrasting patterns in the fate of litter-derived 15N between bioclimatic zones. Over three years, along with faster decay rates, the release of leaf litter-N was faster in sub-taiga than in forest-steppe. As such, higher quantities of 15N were transferred into the soil in sub-taiga. The transfer was also deeper there, which might be related to a more intense drainage because of higher snow levels, as inferred from soil water budget modelling. Interestingly, this higher drainage seems to induce only a small loss of N from the system. Such retention could result from soil physico-chemical properties (higher fine silt and oxides contents) enhancing soil organic matter stabilization, and/or by the immobilization of N in microbial metabolites. We observed differing N dynamics between forest and grassland that can be related to the different chemical composition of initial litter (tree leaves vs. grasses) and plant-soil interactions. In general, N was retained in the first centimeters of the mineral soil in grassland while the transfer was deeper in the forest soils. As fine root exploration is denser in grassland topsoil than in forest topsoil, we infer that an efficient uptake of N by grasses in the first soil layers limits N migration down the profile. It is also possible that grasses are active earlier in the season than trees and understorey species, i.e. at snow-melt when drainage is the most intense.

Eucalyptus microfungi known from culture. 1. Cladoriella and Fulvoflamma genera nova, with notes on some other poorly known taxa

PubMed Central

Crous, Pedro W.; Verkley, Gerard J.M.; Groenewald, Johannes Z.

2006-01-01

A study of microfungi associated with living Eucalyptus leaves and leaf litter revealed several novel and interesting taxa. Cladoriella eucalypti gen. et sp. nov. is described as a Cladosporium-like genus associated with litter collected in South Africa, while Fulvoflamma eucalypti gen. et. sp. nov. is newly described from leaf litter collected in Spain. Beta-conidia are newly reported for species of Pestalotiopsis, namely Pestalotiopsis disseminata in New Zealand, and a Pestalotiopsis sp. from Colombia. Satchmopsis brasiliensis is reported from litter in Colombia and Indonesia, while Torrendiella eucalypti is reported from leaf litter in Indonesia, and shown to have a Sporothrix-like anamorph. Leptospora rubella is reported from living Eucalyptus leaves in Colombia, where it is associated with leaf spots of Mycosphaerella longibasalis, while Macrohilum eucalypti is reported from leaf spots of Eucalyptus in New Zealand. PMID:18490971

Litter chemistry prevails over litter consumers in mediating effects of past steel industry activities on leaf litter decomposition.

PubMed

Lucisine, Pierre; Lecerf, Antoine; Danger, Michaël; Felten, Vincent; Aran, Delphine; Auclerc, Apolline; Gross, Elisabeth M; Huot, Hermine; Morel, Jean-Louis; Muller, Serge; Nahmani, Johanne; Maunoury-Danger, Florence

2015-12-15

Soil pollution has adverse effects on the performance and life history traits of microorganisms, plants, and animals, yet evidence indicates that even the most polluted sites can support structurally-complex and dynamic ecosystems. The present study aims at determining whether and how litter decomposition, one of the most important soil ecological processes leaf, is affected in a highly trace-metal polluted site. We postulated that past steel mill activities resulting in soil pollution and associated changes in soil characteristics would influence the rate of litter decomposition through two non-exclusive pathways: altered litter chemistry and responses of decomposers to lethal and sub-lethal toxic stress. We carried out a litter-bag experiment using Populus tremula L. leaf litter collected at, and allowed to decompose in, a trace metal polluted site and in three unpolluted sites used as controls. We designed a fully-factorial transplant experimental design to assess effects of litter origin and exposure site on the rate of litter decomposition. We further determined initial litter chemistry, fungal biomass, mesofauna abundance in litter bags, and the soil macrofauna community. Irrespective of the site of litter exposure, litter originating from the polluted site had a two-fold faster decomposition than litter from the unpolluted sites. Litter chemistry, notably the lignin content, seemed most important in explaining the degradation rate of the leaf litter. Abundance of meso and macro-detritivores was higher at the polluted site than at the unpolluted sites. However, litter decomposition proceeded at similar rates in polluted and unpolluted sites. Our results show that trace metal pollution and associated soil and litter changes do not necessarily weaken consumer control on litter decomposition through lethal and sub-lethal toxic stress. Copyright © 2015. Published by Elsevier B.V.

Controls on mass loss and nitrogen dynamics of oak leaf litter along an urban-rural land-use gradient

Treesearch

Richard V. Pouyat; Margaret M. Carreiro

2003-01-01

Using reciprocal leaf litter transplants, we investigated the effects of contrasting environments (urban vs. rural) and intraspecific variations in oak leaf litter quality on mass loss rates and nitrogen (N) dynamics along an urban-rural gradient in the New York City metropolitan area. Differences in earthworm abundances and temperature had previously been documented...

Leaf litter decomposition and elemental change in three Appalachian mountain streams of different pH

Treesearch

Steven W. Solada; Sue A. Perry; William B. Perry

1996-01-01

The decomposition of leaf litter provides the primary nutrient source for many of the headwater mountain streams in forested catchments. An investigation of factors affected by global change that influence organic matter decomposition, such as temperature and pH, is important in understanding the dynamics of these systems. We conducted a study of leaf litter elemental...

Variable response by aquatic invertebrates to experimental manipulations of leaf litter input into seasonal woodland ponds

Treesearch

Darold P. Batzer; Brian J. Palik

2007-01-01

Aquatic invertebrates are crucial components of foodwebs in seasonal woodland ponds, and leaf litter is probably the most important food resource for those organisms. We quantified the influence of leaf litter inputs on aquatic invertebrates in two seasonal woodland ponds using an interception experiment. Ponds were hydrologically split using a sandbag-plastic barrier...

Energy content in dried leaf litter of some oaks and mixed mesophytic species that replace oaks

Treesearch

Aaron D. Stottlemeyer; G. Geoff Wang; Patrick H. Brose; Thomas A. Waldrop

2010-01-01

Mixed-mesophytic hardwood tree species are replacing upland oaks in vast areas of the Eastern United States deciduous forest. Some researchers have suggested that the leaf litter of mixed-mesophytic, oak replacement species renders forests less flammable where forest managers wish to restore a natural fire regime. We performed chemical analyses on dried leaf litter...

Plant structure predicts leaf litter capture in the tropical montane bromeliad Tillandsia turneri.

PubMed

Ospina-Bautista, F; Estévez Varón, J V

2016-05-03

Leaves intercepted by bromeliads become an important energy and matter resource for invertebrate communities, bacteria, fungi, and the plant itself. The relationship between bromeliad structure, defined as its size and complexity, and accumulated leaf litter was studied in 55 bromeliads of Tillandsia turneri through multiple regression and the Akaike information criterion. Leaf litter accumulation in bromeliads was best explained by size and complexity variables such as plant cover, sheath length, and leaf number. In conclusion, plant structure determines the amount of litter that enters bromeliads, and changes in its structure could affect important processes within ecosystem functioning or species richness.

Conspecific Leaf Litter-Mediated Effect of Conspecific Adult Neighborhood on Early-Stage Seedling Survival in A Subtropical Forest

PubMed Central

Liu, Heming; Shen, Guochun; Ma, Zunping; Yang, Qingsong; Xia, Jianyang; Fang, Xiaofeng; Wang, Xihua

2016-01-01

Conspecific adults have strong negative effect on the survival of nearby early-stage seedlings and thus can promote species coexistence by providing space for the regeneration of heterospecifics. The leaf litter fall from the conspecific adults, and it could mediate this conspecific negative adult effect. However, field evidence for such effect of conspecific leaf litter remains absent. In this study, we used generalized linear mixed models to assess the effects of conspecific leaf litter on the early-stage seedling survival of four dominant species (Machilus leptophylla, Litsea elongate, Acer pubinerve and Distylium myricoides) in early-stage seedlings in a subtropical evergreen broad-leaved forest in eastern China. Our results consistently showed that the conspecific leaf litter of three species negatively affected the seedling survival. Meanwhile, the traditional conspecific adult neighborhood indices failed to detect this negative conspecific adult effect. Our study revealed that the accumulation of conspecific leaf litter around adults can largely reduce the survival rate of nearby seedlings. Ignoring it could result in underestimation of the importance of negative density dependence and negative species interactions in the natural forest communities. PMID:27886275

Conspecific Leaf Litter-Mediated Effect of Conspecific Adult Neighborhood on Early-Stage Seedling Survival in A Subtropical Forest.

PubMed

Liu, Heming; Shen, Guochun; Ma, Zunping; Yang, Qingsong; Xia, Jianyang; Fang, Xiaofeng; Wang, Xihua

2016-11-25

Conspecific adults have strong negative effect on the survival of nearby early-stage seedlings and thus can promote species coexistence by providing space for the regeneration of heterospecifics. The leaf litter fall from the conspecific adults, and it could mediate this conspecific negative adult effect. However, field evidence for such effect of conspecific leaf litter remains absent. In this study, we used generalized linear mixed models to assess the effects of conspecific leaf litter on the early-stage seedling survival of four dominant species (Machilus leptophylla, Litsea elongate, Acer pubinerve and Distylium myricoides) in early-stage seedlings in a subtropical evergreen broad-leaved forest in eastern China. Our results consistently showed that the conspecific leaf litter of three species negatively affected the seedling survival. Meanwhile, the traditional conspecific adult neighborhood indices failed to detect this negative conspecific adult effect. Our study revealed that the accumulation of conspecific leaf litter around adults can largely reduce the survival rate of nearby seedlings. Ignoring it could result in underestimation of the importance of negative density dependence and negative species interactions in the natural forest communities.

Shrub encroachment in Arctic tundra: Betula nana effects on above- and belowground litter decomposition.

PubMed

McLaren, Jennie R; Buckeridge, Kate M; van de Weg, Martine J; Shaver, Gaius R; Schimel, Joshua P; Gough, Laura

2017-05-01

Rapid arctic vegetation change as a result of global warming includes an increase in the cover and biomass of deciduous shrubs. Increases in shrub abundance will result in a proportional increase of shrub litter in the litter community, potentially affecting carbon turnover rates in arctic ecosystems. We investigated the effects of leaf and root litter of a deciduous shrub, Betula nana, on decomposition, by examining species-specific decomposition patterns, as well as effects of Betula litter on the decomposition of other species. We conducted a 2-yr decomposition experiment in moist acidic tundra in northern Alaska, where we decomposed three tundra species (Vaccinium vitis-idaea, Rhododendron palustre, and Eriophorum vaginatum) alone and in combination with Betula litter. Decomposition patterns for leaf and root litter were determined using three different measures of decomposition (mass loss, respiration, extracellular enzyme activity). We report faster decomposition of Betula leaf litter compared to other species, with support for species differences coming from all three measures of decomposition. Mixing effects were less consistent among the measures, with negative mixing effects shown only for mass loss. In contrast, there were few species differences or mixing effects for root decomposition. Overall, we attribute longer-term litter mass loss patterns to patterns created by early decomposition processes in the first winter. We note numerous differences for species patterns between leaf and root decomposition, indicating that conclusions from leaf litter experiments should not be extrapolated to below-ground decomposition. The high decomposition rates of Betula leaf litter aboveground, and relatively similar decomposition rates of multiple species below, suggest a potential for increases in turnover in the fast-decomposing carbon pool of leaves and fine roots as the dominance of deciduous shrubs in the Arctic increases, but this outcome may be tempered by negative litter mixing effects during the early stages of encroachment. © 2017 by the Ecological Society of America.

Experimental evidence that the Ornstein-Uhlenbeck model best describes the evolution of leaf litter decomposability

PubMed Central

Pan, Xu; Cornelissen, Johannes H C; Zhao, Wei-Wei; Liu, Guo-Fang; Hu, Yu-Kun; Prinzing, Andreas; Dong, Ming; Cornwell, William K

2014-01-01

Leaf litter decomposability is an important effect trait for ecosystem functioning. However, it is unknown how this effect trait evolved through plant history as a leaf ‘afterlife’ integrator of the evolution of multiple underlying traits upon which adaptive selection must have acted. Did decomposability evolve in a Brownian fashion without any constraints? Was evolution rapid at first and then slowed? Or was there an underlying mean-reverting process that makes the evolution of extreme trait values unlikely? Here, we test the hypothesis that the evolution of decomposability has undergone certain mean-reverting forces due to strong constraints and trade-offs in the leaf traits that have afterlife effects on litter quality to decomposers. In order to test this, we examined the leaf litter decomposability and seven key leaf traits of 48 tree species in the temperate area of China and fitted them to three evolutionary models: Brownian motion model (BM), Early burst model (EB), and Ornstein-Uhlenbeck model (OU). The OU model, which does not allow unlimited trait divergence through time, was the best fit model for leaf litter decomposability and all seven leaf traits. These results support the hypothesis that neither decomposability nor the underlying traits has been able to diverge toward progressively extreme values through evolutionary time. These results have reinforced our understanding of the relationships between leaf litter decomposability and leaf traits in an evolutionary perspective and may be a helpful step toward reconstructing deep-time carbon cycling based on taxonomic composition with more confidence. PMID:25535551

Accounting for non-photosynthetic vegetation in remote-sensing-based estimates of carbon flux in wetlands

USGS Publications Warehouse

Schile, Lisa M.; Byrd, Kristin B.; Windham-Myers, Lisamarie; Kelly, Maggi

2013-01-01

Monitoring productivity in coastal wetlands is important due to their high carbon sequestration rates and potential role in climate change mitigation. We tested agricultural- and forest-based methods for estimating the fraction of absorbed photosynthetically active radiation (f APAR), a key parameter for modelling gross primary productivity (GPP), in a restored, managed wetland with a dense litter layer of non-photosynthetic vegetation, and we compared the difference in canopy light transmission between a tidally influenced wetland and the managed wetland. The presence of litter reduced correlations between spectral vegetation indices and f APAR. In the managed wetland, a two-band vegetation index incorporating simulated World View-2 or Hyperion green and near-infrared bands, collected with a field spectroradiometer, significantly correlated with f APAR only when measured above the litter layer, not at the ground where measurements typically occur. Measures of GPP in these systems are difficult to capture via remote sensing, and require an investment of sampling effort, practical methods for measuring green leaf area and accounting for background effects of litter and water.

Temperatures below leaf litter during winter prescribed burns: implications for litter-roosting bats

Treesearch

Roger W. Perry; Virginia L. McDaniel

2015-01-01

Some bat species, including eastern red bats (Lasiurus borealis), roost for short periods beneath leaf litter on the forest floor during winter in the south-eastern USA, a region subjected to frequent fire. The variability in fuel consumption, the heterogeneous nature of burns, and the effects of litter and duff moisture on forest-floor...

The Role of Mycorrhizal Associations in Controlling Biogenic Volatile Organic Carbon Flux From a Temperate Deciduous Forest

NASA Astrophysics Data System (ADS)

Cook, A. A.; Trowbridge, A.; Jacobs, L. M.; Stoy, P. C.; Stevens, P. S.; Phillips, R.

2016-12-01

The sources of and controls over biogenic volatile organic compound (bVOC) fluxes between terrestrial ecosystems and the atmosphere remains poorly understood. Ecosystem bVOC flux models rarely include contributions from leaf litter and soils despite recent findings demonstrating that they can be nontrivial components of total ecosystem bVOC flux. Other recent studies have demonstrated the central role of arbuscular (AM) versus ectomycorrhizal (ECM) fungi in determining litter quality and soil biogeochemistry. Here, we quantify the role of mycorrhizal associations in controlling soil and leaf litter bVOC flux during the growing to non-growing season transition at the Morgan Monroe State Forest Ameriflux Core research site in Indiana, USA. We hypothesize that (1) total bVOC emissions will be greater from ECM plots due to larger belowground microbial biomass, and (2) fast-decomposing litter within the AM-dominated plots will result in an ephemeral pulse in bVOC emissions later in the season. AM and ECM-dominated forest soils were a net bVOC sink early in the growing season following leaf-out, but were net sources during the leaf-fall period in October. In the absence of leaf litter, soils dominated by ECM were a large sink of bVOCs, but leaf litter inputs resulted in a net source, suggesting that leaf litter and not merely soil microbial biomass is critical for understanding hypothesis (1). Temperature explains 57% (21%) of the variability of methanol flux - the bVOC of greatest quantity - in ECM (AM)-dominated plots. Non-methanol bVOC flux is only related to soil temperature in the Fall in ECM-dominated plots, where it explains 71% of the variability. Results are consistent with large methanol efflux with fresh litter after leaf-fall, especially in ECM plots (contrary to hypothesis 2), but net uptake with strong temperature-dependence during the growing season. Seasonality, phenology (including leaf litter dynamics) and mycorrhizal associations should be taken into account to accurately determine the relative contribution of forest soils to ecosystem bVOC fluxes in temperate forests and their sensitivity to environmental drivers.

Flammability across the gymnosperm phylogeny: the importance of litter particle size.

PubMed

Cornwell, William K; Elvira, Alba; van Kempen, Lute; van Logtestijn, Richard S P; Aptroot, André; Cornelissen, J Hans C

2015-04-01

Fire is important to climate, element cycles and plant communities, with many fires spreading via surface litter. The influence of species on the spread of surface fire is mediated by their traits which, after senescence and abscission, have 'afterlife' effects on litter flammability. We hypothesized that differences in litter flammability among gymnosperms are determined by litter particle size effects on litterbed packing. We performed a mesocosm fire experiment comparing 39 phylogenetically wide-ranging gymnosperms, followed by litter size and shape manipulations on two chemically contrasting species, to isolate the underlying mechanism. The first-order control on litter flammability was, indeed, litter particle size in both experiments. Most gymnosperms were highly flammable, but a prominent exception was the non-Pinus Pinaceae, in which small leaves abscised singly produced dense, non-flammable litterbeds. There are two important implications: first, ecosystems dominated by gymnosperms that drop small leaves separately will develop dense litter layers, which will be less prone to and inhibit the spread of surface litter fire. Second, some of the needle-leaved species previously considered to be flammable in single-leaf experiments were among the least flammable in litter fuel beds, highlighting the role of the litter traits of species in affecting surface fire regimes. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Litter Breakdown and Microbial Succession on Two Submerged Leaf Species in a Small Forested Stream

PubMed Central

Newman, Molli M.; Liles, Mark R.; Feminella, Jack W.

2015-01-01

Microbial succession during leaf breakdown was investigated in a small forested stream in west-central Georgia, USA, using multiple culture-independent techniques. Red maple (Acer rubrum) and water oak (Quercus nigra) leaf litter were incubated in situ for 128 days, and litter breakdown was quantified by ash-free dry mass (AFDM) method and microbial assemblage composition using phospholipid fatty acid analysis (PLFA), ribosomal intergenic spacer analysis (RISA), denaturing gradient gel electrophoresis (DGGE), and bar-coded next-generation sequencing of 16S rRNA gene amplicons. Leaf breakdown was faster for red maple than water oak. PLFA revealed a significant time effect on microbial lipid profiles for both leaf species. Microbial assemblages on maple contained a higher relative abundance of bacterial lipids than oak, and oak microbial assemblages contained higher relative abundance of fungal lipids than maple. RISA showed that incubation time was more important in structuring bacterial assemblages than leaf physicochemistry. DGGE profiles revealed high variability in bacterial assemblages over time, and sequencing of DGGE-resolved amplicons indicated several taxa present on degrading litter. Next-generation sequencing revealed temporal shifts in dominant taxa within the phylum Proteobacteria, whereas γ-Proteobacteria dominated pre-immersion and α- and β-Proteobacteria dominated after 1 month of instream incubation; the latter groups contain taxa that are predicted to be capable of using organic material to fuel further breakdown. Our results suggest that incubation time is more important than leaf species physicochemistry in influencing leaf litter microbial assemblage composition, and indicate the need for investigation into seasonal and temporal dynamics of leaf litter microbial assemblage succession. PMID:26098687

Comparing intra- and inter-specific effects on litter decomposition in an old-field ecosystem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crutsinger, Greg; Sanders, Dr. Nathan James; Classen, Aimee T

2009-09-01

Plant species can differ in the quantity and quality of leaf litter they produce, and many studies have examined whether plant species diversity affects leaf-litter decomposition and nutrient release. A growing number of studies have indicated that intra-specific variation within plant species can also affect key ecosystem processes. However, the relative importance of intra- versus inter-specific variation for the functioning of ecosystems remains poorly known. Here, we investigate the effects of intra-specific variation in a dominant old-field plant species, tall goldenrod (Solidago altissima), and inter-specific variation among goldenrod species on litter quality, decomposition, and nitrogen (N) release. We found thatmore » the nutrient concentration of leaf litter varied among genotypes, which translated into 50% difference in decomposition rates. Variation among other goldenrod species in decomposition rate was more than twice that of genetic variation within S. altissima. Furthermore, by manipulating litterbags to contain 1, 3, 6, or 9 genotypes, we found that S. altissima genotype identity had much stronger effects than did genotypic diversity on leaf-litter quality, decomposition, and N release. Taken together, these results suggest that the order of ecological importance for controlling leaf-litter decomposition and N release dynamics is plant species identitygenotype identity>genotypic diversity.« less

Differential effects of conifer and broadleaf litter inputs on soil organic carbon chemical composition through altered soil microbial community composition

PubMed Central

Wang, Hui; Liu, Shi-Rong; Wang, Jing-Xin; Shi, Zuo-Min; Xu, Jia; Hong, Pi-Zheng; Ming, An-Gang; Yu, Hao-Long; Chen, Lin; Lu, Li-Hua; Cai, Dao-Xiong

2016-01-01

A strategic selection of tree species will shift the type and quality of litter input, and subsequently magnitude and composition of the soil organic carbon (SOC) through soil microbial community. We conducted a manipulative experiment in randomized block design with leaf litter inputs of four native subtropical tree species in a Pinus massoniana plantation in southern China and found that the chemical composition of SOC did not differ significantly among treatments until after 28 months of the experiment. Contrasting leaf litter inputs had significant impacts on the amounts of total microbial, Gram-positive bacterial, and actinomycic PLFAs, but not on the amounts of total bacterial, Gram-negative bacterial, and fungal PLFAs. There were significant differences in alkyl/O-alkyl C in soils among the leaf litter input treatments, but no apparent differences in the proportions of chemical compositions (alkyl, O-alkyl, aromatic, and carbonyl C) in SOC. Soil alkyl/O-alkyl C was significantly related to the amounts of total microbial, and Gram-positive bacterial PLFAs, but not to the chemical compositions of leaf litter. Our findings suggest that changes in forest leaf litter inputs could result in changes in chemical stability of SOC through the altered microbial community composition. PMID:27256545

Differential effects of conifer and broadleaf litter inputs on soil organic carbon chemical composition through altered soil microbial community composition.

PubMed

Wang, Hui; Liu, Shi-Rong; Wang, Jing-Xin; Shi, Zuo-Min; Xu, Jia; Hong, Pi-Zheng; Ming, An-Gang; Yu, Hao-Long; Chen, Lin; Lu, Li-Hua; Cai, Dao-Xiong

2016-06-03

A strategic selection of tree species will shift the type and quality of litter input, and subsequently magnitude and composition of the soil organic carbon (SOC) through soil microbial community. We conducted a manipulative experiment in randomized block design with leaf litter inputs of four native subtropical tree species in a Pinus massoniana plantation in southern China and found that the chemical composition of SOC did not differ significantly among treatments until after 28 months of the experiment. Contrasting leaf litter inputs had significant impacts on the amounts of total microbial, Gram-positive bacterial, and actinomycic PLFAs, but not on the amounts of total bacterial, Gram-negative bacterial, and fungal PLFAs. There were significant differences in alkyl/O-alkyl C in soils among the leaf litter input treatments, but no apparent differences in the proportions of chemical compositions (alkyl, O-alkyl, aromatic, and carbonyl C) in SOC. Soil alkyl/O-alkyl C was significantly related to the amounts of total microbial, and Gram-positive bacterial PLFAs, but not to the chemical compositions of leaf litter. Our findings suggest that changes in forest leaf litter inputs could result in changes in chemical stability of SOC through the altered microbial community composition.

Differential effects of conifer and broadleaf litter inputs on soil organic carbon chemical composition through altered soil microbial community composition

NASA Astrophysics Data System (ADS)

Wang, Hui; Liu, Shi-Rong; Wang, Jing-Xin; Shi, Zuo-Min; Xu, Jia; Hong, Pi-Zheng; Ming, An-Gang; Yu, Hao-Long; Chen, Lin; Lu, Li-Hua; Cai, Dao-Xiong

2016-06-01

A strategic selection of tree species will shift the type and quality of litter input, and subsequently magnitude and composition of the soil organic carbon (SOC) through soil microbial community. We conducted a manipulative experiment in randomized block design with leaf litter inputs of four native subtropical tree species in a Pinus massoniana plantation in southern China and found that the chemical composition of SOC did not differ significantly among treatments until after 28 months of the experiment. Contrasting leaf litter inputs had significant impacts on the amounts of total microbial, Gram-positive bacterial, and actinomycic PLFAs, but not on the amounts of total bacterial, Gram-negative bacterial, and fungal PLFAs. There were significant differences in alkyl/O-alkyl C in soils among the leaf litter input treatments, but no apparent differences in the proportions of chemical compositions (alkyl, O-alkyl, aromatic, and carbonyl C) in SOC. Soil alkyl/O-alkyl C was significantly related to the amounts of total microbial, and Gram-positive bacterial PLFAs, but not to the chemical compositions of leaf litter. Our findings suggest that changes in forest leaf litter inputs could result in changes in chemical stability of SOC through the altered microbial community composition.

Leaf litter processing in West Virginia mountain streams: effects of temperature and stream chemistry

Treesearch

Jacquelyn M. Rowe; William B. Perry; Sue A. Perry

1996-01-01

Climate change has the potential to alter detrital processing in headwater streams, which receive the majority of their nutrient input as terrestrial leaf litter. Early placement of experimental leaf packs in streams, one month prior to most abscission, was used as an experimental manipulation to increase stream temperature during leaf pack breakdown. We studied leaf...

Dissolved organic carbon biodegradability from leaf litter leachates of riparian tropical trees

NASA Astrophysics Data System (ADS)

Bastianoni, A.; Montoya, J. V.; Mendez, C.; Paolini, J.

2012-04-01

It is generally assumed that leaf litter with varying chemical composition may show different rates of mass loss, dissolved organic carbon (DOC) release, and DOC biodegradability. Leaf litter is composed of different organic compounds, which may differ in their release rates. Some authors consider leaf litter chemical quality (carbon to nitrogen ratio (C:N) and polyphenolics content) as an indicator of leaf litter mass losses and DOC released into stream water through leaching. In this research, we determined if leachate's DOC biodegradability exhibited a positive relationship with leaf litter chemical quality and leaf litter mass loss due to leaching. In order to test these hypotheses, leaf litter from six riparian tree species (Bambusa vulgaris; Castilla elastica; Artocarpus altilis; Cecropia peltata; Hura crepitans and Ficus maxima), present in the lower reaches of a fifth-order stream in northern Venezuela was collected during the dry season of 2010. To evaluate leaf litter mass loss, air-dried leaves were incubated in Milli-Q water at room temperature in the dark. After 1h, 6h, 1d, 2d, 4d, 8d and 15d, microcosms were removed from the assay to determine remaining mass. DOC biodegradability was measured using 24 h leachates that were added into a 1L glass flask containing 250mL of unfiltered stream water, 4g of stream sediment, and nutrient amendments until all incubations had equal initial DOC concentrations. Biodegradability of DOC was measured at 0, 1, 2, 5 and 7 days as the decrease in DOC concentration through time. Chemical characterization of leaf litter involved the determination of total concentrations of C, N, and poliphenolics. Three replicates were used for all analyses. Initial chemical characterization of leaf litter showed that only two species (C. elastica and A. altilis), had similar C:N ratios (~31). The other four species, showed different C and N contents but presented C:N ratios between 21 and 23. Total polyphenolics content varied greatly among species. Based on the degree of DOC biodegradability, after 1d of incubation, all species could be grouped into three distinct categories (high, intermediate and low). Then, biodegradability of DOC declined steadily until reaching near-constant values at day 7 probably reflecting less availability of labile C compounds. Breakdown rates were not significantly correlated with DOC decay rates (r=-0.580, P =0.228, n=6). However when the remaining DOC and the remaining mass for all species was evaluated, a significant negative correlation was observed (r=-0.567, P =0.014, n=18) contradicting our initial hypothesis. Such results might be a consequence of the presence of secondary metabolites alongside labile DOC in some species leachates which could prevent microbial C consumption. Therefore, the quality of C released by leaching, measured as its biodegradability, does not seem to have a relationship with the amount of C lost by leaching. This could influence the C budget of the riparian ecosystem since the proportion of C consumed by stream microbes is affected by the chemical quality of leaf litter leachates.

Ephemeroptera, Plecoptera and Trichoptera (Insecta) Abundance, Diversity and Role in Leaf Litter Breakdown in Tropical Headwater River

PubMed Central

Ab Hamid, Suhaila; Md Rawi, Che Salmah

2017-01-01

Leaf litter decomposition in a tropical stream was examined in two types of leaf packs; single species leaf packs of Pometia pinnata and two species leaf packs of equal combination of Pometia pinnata and Dolichandrone spathacea leaves. Both leaf packs were immersed in a river and weekly examined for remains of decomposed leaves and presence of EPT. In the control leaf packs, leaves in the two species leaf packs treatments decomposed within 35 days, faster than in single species leaf packs which decomposed after 42 days. In the presence of EPT, the leaf breakdown took 28 days in two species and 35 days for single species leaf packs. Higher abundance of EPT was observed in single species leaf packs but its diversity was higher in two species leaf packs. Litter breakdown in the stream was faster in the presence of EPT and softer leaves of D. spathacea with higher nitrogen content underwent faster decomposition and sustained higher numbers of EPT. PMID:28890763

Ephemeroptera, Plecoptera and Trichoptera (Insecta) Abundance, Diversity and Role in Leaf Litter Breakdown in Tropical Headwater River.

PubMed

Ab Hamid, Suhaila; Md Rawi, Che Salmah

2017-07-01

Leaf litter decomposition in a tropical stream was examined in two types of leaf packs; single species leaf packs of Pometia pinnata and two species leaf packs of equal combination of Pometia pinnata and Dolichandrone spathacea leaves. Both leaf packs were immersed in a river and weekly examined for remains of decomposed leaves and presence of EPT. In the control leaf packs, leaves in the two species leaf packs treatments decomposed within 35 days, faster than in single species leaf packs which decomposed after 42 days. In the presence of EPT, the leaf breakdown took 28 days in two species and 35 days for single species leaf packs. Higher abundance of EPT was observed in single species leaf packs but its diversity was higher in two species leaf packs. Litter breakdown in the stream was faster in the presence of EPT and softer leaves of D. spathacea with higher nitrogen content underwent faster decomposition and sustained higher numbers of EPT.

Population dynamics of the rubber plantation litter beetle Luprops tristis, in relation to annual cycle of foliage phenology of its host, the para rubber tree, Hevea brasiliensis.

PubMed

Sabu, Thomas K; Vinod, K V

2009-01-01

The population dynamics of the rubber plantation litter beetle, Luprops tristis Fabricius 1801 (Coleoptera: Tenebrionidae) was assessed in relation to the phenology of leaf shedding and defoliation pattern of para rubber trees, Hevea brasiliensis Müll. Arg (Malpighiales: Euphorbiaceae), during a two year study period. The abundance of adults, larvae and pupae per 1m(2) of litter sample was recorded. Post dormancy beetles appeared in leaf litter following annual leaf shedding, whereas larvae, pupae and teneral adults were present after leaf flush. No stages were recorded from plantations following the summer rains until the annual litter fall in the next season. Parental adults peaked at the time of leaf sprouting and tender leaf fall. Larvae and teneral adults peaked at the time of premature fall of green leaves and flowers. Teneral adults of six age classes were recorded and all entered dormancy irrespective of the feeding time available to each age class. Females outnumbered males in the parent generation, while the sex ratio of new generation adults was not biased towards either sex. The phenological stages of rubber trees included leaf fall in late December and early January, leaf sprouting and new leaf production in January and flowering in February. All feeding stages of L. tristis peaked in abundance when premature leaves are most abundant in the leaf litter. Prediction of the timing of appearance of various developmental stages of L. tristis in plantations, invasion into buildings and intensity of population build up in rubber belts is possible by tracking the phenology of leaf fall in rubber plantations, time of return of post dormancy adults and the onset of summer rainfall. Perfect synchrony was recorded between the field return of parental adults with annual leaf shedding, the oviposition phase of parental adults with tender leaf fall at the time of leaf sprouting, and larval and teneral adult stages with premature fall of leaves. Premature leaf availability is suggested as contributing to the reproductive efficiency of parental adults, the survival of early developmental stages and of new generation adults during dormancy.

Population Dynamics of the Rubber Plantation Litter Beetle Luprops tristis, in Relation to Annual Cycle of Foliage Phenology of Its Host, the Para Rubber Tree, Hevea brasiliensis

PubMed Central

Sabu, Thomas K.; Vinod, K.V.

2009-01-01

The population dynamics of the rubber plantation litter beetle, Luprops tristis Fabricius 1801 (Coleoptera: Tenebrionidae) was assessed in relation to the phenology of leaf shedding and defoliation pattern of para rubber trees, Hevea brasiliensis Müll. Arg (Malpighiales: Euphorbiaceae), during a two year study period. The abundance of adults, larvae and pupae per 1m2 of litter sample was recorded. Post dormancy beetles appeared in leaf litter following annual leaf shedding, whereas larvae, pupae and teneral adults were present after leaf flush. No stages were recorded from plantations following the summer rains until the annual litter fall in the next season. Parental adults peaked at the time of leaf sprouting and tender leaf fall. Larvae and teneral adults peaked at the time of premature fall of green leaves and flowers. Teneral adults of six age classes were recorded and all entered dormancy irrespective of the feeding time available to each age class. Females outnumbered males in the parent generation, while the sex ratio of new generation adults was not biased towards either sex. The phenological stages of rubber trees included leaf fall in late December and early January, leaf sprouting and new leaf production in January and flowering in February. All feeding stages of L. tristis peaked in abundance when premature leaves are most abundant in the leaf litter. Prediction of the timing of appearance of various developmental stages of L. tristis in plantations, invasion into buildings and intensity of population build up in rubber belts is possible by tracking the phenology of leaf fall in rubber plantations, time of return of post dormancy adults and the onset of summer rainfall. Perfect synchrony was recorded between the field return of parental adults with annual leaf shedding, the oviposition phase of parental adults with tender leaf fall at the time of leaf sprouting, and larval and teneral adult stages with premature fall of leaves. Premature leaf availability is suggested as contributing to the reproductive efficiency of parental adults, the survival of early developmental stages and of new generation adults during dormancy. PMID:20050775

Effects of invasive European bird cherry (Prunus padus) on leaf litter processing by aquatic invertebrate shredder communities in urban Alaskan streams

USGS Publications Warehouse

Roon, David A.; Wipfli, Mark S.; Wurtz, Tricia L.

2014-01-01

European bird cherry (Prunus padus) (EBC) is an invasive ornamental tree that is spreading rapidly in riparian forests of urban Alaska. To determine how the spread of EBC affects leaf litter processing by aquatic invertebrate shredders, we conducted complementary leaf pack experiments in two streams located in Anchorage, Alaska. The first experiment contrasted invasive EBC with three native tree species—thin-leaf alder (Alnus tenuifolia), paper birch (Betula neoalaskana), and black cottonwood (Populus trichocarpa)—in one reach of Chester Creek; finding that EBC leaf litter broke down significantly faster than birch and cottonwood, but at a similar rate to alder. The second experiment contrasted EBC with alder in four reaches of Campbell and Chester creeks; finding that while EBC leaf litter broke down significantly faster than alder in Chester Creek, EBC broke down at a similar rate to alder in Campbell Creek. Although EBC sometimes supported fewer shredders by both count and mass, shredder communities did not differ significantly between EBC and native plants. Collectively, these data suggest that invasive EBC is not currently exhibiting strong negative impacts on leaf litter processing in these streams, but could if it continues to spread and further displaces native species over time.

Comparison Between Ground Ant (Hymenoptera: Formicidae) Communities Foraging in the Straw Mulch of Sugarcane Crops and in the Leaf Litter of Neighboring Forests.

PubMed

Silva, N S; Saad, L P; Souza-Campana, D R; Bueno, O C; Morini, M S C

2017-02-01

In many sugarcane plantations in Brazil, the straw is left on the soil after harvesting, and vinasse, a by-product of the production of sugar and ethanol, is used for fertigation. Our goal was to compare ant community composition and species richness in the straw mulch of sugarcane crops with the leaf litter of neighboring forests. We tested the hypothesis that ant communities in the straw mulch of vinasse-irrigated sugarcane crops and in the forest leaf litter were similar, because the combination of straw mulching and vinasse irrigation has a positive effect on soil fauna. Straw mulch and leaf litter were collected from 21 sites and placed in Berlese funnels. In total, 61 species were found in the forest leaf litter, whereas 34 and 28 species were found in the straw mulch of sugarcane fields with and without vinasse, respectively. Ant communities differed between forest and crop fields, but the species in the sugarcane straw mulch were a subset of the species found in the forest leaf litter. Although vinasse is rich in organic matter, it did not increase ant diversity. Seven feeding and/or foraging types were identified and, among the different types, surface-foraging omnivorous ants were the most prevalent in all habitats. Vinasse-irrigated sugarcane straw mulch had more predatory species than mulch from vinasse-free fields, but fewer than forest leaf litter. However, this positive effect of vinasse irrigation should be carefully evaluated because vinasse has negative effects on the environment. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Leaf litter breakdown, microbial respiration and shredder production in metal-polluted streams

USGS Publications Warehouse

Carlisle, D.M.; Clements, W.H.

2005-01-01

1. If species disproportionately influence ecosystem functioning and also differ in their sensitivities to environmental conditions, the selective removal of species by anthropogenic stressors may lead to strong effects on ecosystem processes. We evaluated whether these circumstances held for several Colorado, U.S.A. streams stressed by Zn. 2. Benthic invertebrates and chemistry were sampled in five second-third order streams for 1 year. Study streams differed in dissolved metal concentrations, but were otherwise similar in chemical and physical characteristics. Secondary production of leaf-shredding insects was estimated using the increment summation and size-frequency methods. Leaf litter breakdown rates were estimated by retrieving litter-bags over a 171 day period. Microbial activity on leaf litter was measured in the laboratory using changes in oxygen concentration over a 48 h incubation period. 3. Dissolved Zn concentrations varied eightfold among two reference and three polluted streams. Total secondary production of shredders was negatively associated with metal contamination. Secondary production in reference streams was dominated by Taenionema pallidum. Results of previous studies and the current investigation demonstrate that this shredder is highly sensitive to metals in Colorado headwater streams. Leaf litter breakdown rates were similar between reference streams and declined significantly in the polluted streams. Microbial respiration at the most contaminated site was significantly lower than at reference sites. 4. Our results supported the hypothesis that some shredder species contribute disproportionately to leaf litter breakdown. Furthermore, the functionally dominant taxon was also the most sensitive to metal contamination. We conclude that leaf litter breakdown in our study streams lacked functional redundancy and was therefore highly sensitive to contaminant-induced alterations in community structure. We argue for the necessity of simultaneously measuring community structure and ecosystem function in anthropogenically stressed ecosystems.

Leaf litter traits of invasive species slow down decomposition compared to Spanish natives: a broad phylogenetic comparison.

PubMed

Godoy, Oscar; Castro-Díez, Pilar; Van Logtestijn, Richard S P; Cornelissen, Johannes H C; Valladares, Fernando

2010-03-01

Leaf traits related to the performance of invasive alien species can influence nutrient cycling through litter decomposition. However, there is no consensus yet about whether there are consistent differences in functional leaf traits between invasive and native species that also manifest themselves through their "after life" effects on litter decomposition. When addressing this question it is important to avoid confounding effects of other plant traits related to early phylogenetic divergences and to understand the mechanism underlying the observed results to predict which invasive species will exert larger effects on nutrient cycling. We compared initial leaf litter traits, and their effect on decomposability as tested in standardized incubations, in 19 invasive-native pairs of co-familial species from Spain. They included 12 woody and seven herbaceous alien species representative of the Spanish invasive flora. The predictive power of leaf litter decomposition rates followed the order: growth form > family > status (invasive vs. native) > leaf type. Within species pairs litter decomposition tended to be slower and more dependent on N and P in invaders than in natives. This difference was likely driven by the higher lignin content of invader leaves. Although our study has the limitation of not representing the natural conditions from each invaded community, it suggests a potential slowing down of the nutrient cycle at ecosystem scale upon invasion.

Effects of increasing temperature and, CO2 on quality of litter, shredders, and microorganisms in Amazonian aquatic systems

PubMed Central

Rezende, Renan de Souza; Gonçalves Júnior, José Francisco; Lopes, Aline; Piedade, Maria Teresa Fernandez; Cavalcante, Heloide de Lima; Hamada, Neusa

2017-01-01

Climate change may affect the chemical composition of riparian leaf litter and, aquatic organisms and, consequently, leaf breakdown. We evaluated the effects of different scenarios combining increased temperature and carbon dioxide (CO2) on leaf detritus of Hevea spruceana (Benth) Müll. and decomposers (insect shredders and microorganisms). We hypothesized that simulated climate change (warming and elevated CO2) would: i) decrease leaf-litter quality, ii) decrease survival and leaf breakdown by shredders, and iii) increase microbial leaf breakdown and fungal biomass. We performed the experiment in four microcosm chambers that simulated air temperature and CO2 changes in relation to a real-time control tracking current conditions in Manaus, Amazonas, Brazil. The experiment lasted seven days. During the experiment mean air temperature and CO2 concentration ranged from 26.96 ± 0.98ºC and 537.86 ± 18.36 ppmv in the control to 31.75 ± 0.50ºC and 1636.96 ± 17.99 ppmv in the extreme chamber, respectively. However, phosphorus concentration in the leaf litter decreased with warming and elevated CO2. Leaf quality (percentage of carbon, nitrogen, phosphorus, cellulose and lignin) was not influenced by soil flooding. Fungal biomass and microbial leaf breakdown were positively influenced by temperature and CO2 increase and reached their highest values in the intermediate condition. Both total and shredder leaf breakdown, and shredder survival rate were similar among all climatic conditions. Thus, low leaf-litter quality due to climate change and higher leaf breakdown under intermediate conditions may indicate an increase of riparian metabolism due to temperature and CO2 increase, highlighting the risk (e.g., decreased productivity) of global warming for tropical streams. PMID:29190723

Tracing C Fluxes From Leaf Litter To Microbial Respired CO2 And Specific Soil Compounds

NASA Astrophysics Data System (ADS)

Rubino, M.; Lubritto, C.; D'Onofrio, A.; Gleixner, G.; Terrasi, F.; Cotrufo, F. M.

2004-12-01

Despite litter decomposition is one of the major process controlling soil C stores and nutrient cycling, yet C dynamics during litter decay are poorly understood and quantified. Here we report the results of a laboratory experiment where 13C depleted leaf litter was incubated on a 13C enriched soil with the aims to: i) partition the C loss during litter decay into microbial respired-CO2 and C input into the soil; ii) identify the soil compounds where litter derived C is retained; iii) assess whether litter quality is a determinant of both the above processes. Three 13C-depleted leaf litter(delta13C ca. -43), differing in their degradability, were incubated on C4 soil (delta13C ca. -18) under laboratory controlled conditions for 8 months, with litter respiration and delta13C-CO2 being measured at regular intervals. At harvest, Compound Specific Isotope Analyses was performed on soil and litter samples in order to follow the fate of litter-derived C compounds in the various pools of SOMƒn The delta13C of soils carbohydrates, alkanes and Phospho Lipids Fatty Acids (PLFA) were measured, and the mixing model approach used to quantify the contribution of litter derived C to the specific compounds.

Rainfall interception by tree crown and leaf litter: an interactive process

Treesearch

Xiang Li; Qingfu Xiao; Jianzhi Niu; Salli Dymond; E. Gregory McPherson; Natalie van Doorn; Xinxiao Yu; Baoyuan Xie; Kebin Zhang; Jiao Li

2017-01-01

Rainfall interception research in forest ecosystems usually focuses on interception by either tree crown or leaf litter, although the 2 components interact when rainfall occurs. A process-based study was conducted to jointly measure rainfall interception by crown and litter and the interaction between the 2 interception processes for 4 tree species (...

SOA formation potential of emissions from soil and leaf litter.

PubMed

Faiola, Celia L; Vanderschelden, Graham S; Wen, Miao; Elloy, Farah C; Cobos, Douglas R; Watts, Richard J; Jobson, B Thomas; Vanreken, Timothy M

2014-01-21

Soil and leaf litter are significant global sources of small oxidized volatile organic compounds, VOCs (e.g., methanol and acetaldehyde). They may also be significant sources of larger VOCs that could act as precursors to secondary organic aerosol (SOA) formation. To investigate this, soil and leaf litter samples were collected from the University of Idaho Experimental Forest and transported to the laboratory. There, the VOC emissions were characterized and used to drive SOA formation via dark, ozone-initiated reactions. Monoterpenes dominated the emission profile with emission rates as high as 228 μg-C m(-2) h(-1). The composition of the SOA produced was similar to biogenic SOA formed from oxidation of ponderosa pine emissions and α-pinene. Measured soil and litter monoterpene emission rates were compared with modeled canopy emissions. Results suggest surface soil and litter monoterpene emissions could range from 12 to 136% of canopy emissions in spring and fall. Thus, emissions from leaf litter may potentially extend the biogenic emissions season, contributing to significant organic aerosol formation in the spring and fall when reduced solar radiation and temperatures reduce emissions from living vegetation.

A climatic and taxonomic comparison between leaf litter and standing vegetation from a Florida swamp woodland

Treesearch

David L. Dilcher; Elizabeth A. Kowalski; Michael C. Wiemann; Luis Felipe Hinojosa; Terry A. Lott

2009-01-01

One method to determine past climate has been the use of leaf morphological characteristics of fossil leaves quantified using modern climate and canopy leaf characteristics. Fossil assemblages are composed of abscised leaves, and climate may be more accurately determined by using leaves from leaf litter instead of the canopy. To better understand whether taphonomic...

Shifts in leaf litter breakdown along a forest-pasture-urban gradient in Andean streams.

PubMed

Iñiguez-Armijos, Carlos; Rausche, Sirkka; Cueva, Augusta; Sánchez-Rodríguez, Aminael; Espinosa, Carlos; Breuer, Lutz

2016-07-01

Tropical montane ecosystems of the Andes are critically threatened by a rapid land-use change which can potentially affect stream variables, aquatic communities, and ecosystem processes such as leaf litter breakdown. However, these effects have not been sufficiently investigated in the Andean region and at high altitude locations in general. Here, we studied the influence of land use (forest-pasture-urban) on stream physico-chemical variables (e.g., water temperature, nutrient concentration, and pH), aquatic communities (macroinvertebrates and aquatic fungi) and leaf litter breakdown rates in Andean streams (southern Ecuador), and how variation in those stream physico-chemical variables affect macroinvertebrates and fungi related to leaf litter breakdown. We found that pH, water temperature, and nutrient concentration increased along the land-use gradient. Macroinvertebrate communities were significantly different between land uses. Shredder richness and abundance were lower in pasture than forest sites and totally absent in urban sites, and fungal richness and biomass were higher in forest sites than in pasture and urban sites. Leaf litter breakdown rates became slower as riparian land use changed from natural to anthropogenically disturbed conditions and were largely determined by pH, water temperature, phosphate concentration, fungal activity, and single species of leaf-shredding invertebrates. Our findings provide evidence that leaf litter breakdown in Andean streams is sensitive to riparian land-use change, with urban streams being the most affected. In addition, this study highlights the role of fungal biomass and shredder species (Phylloicus; Trichoptera and Anchytarsus; Coleoptera) on leaf litter breakdown in Andean streams and the contribution of aquatic fungi in supporting this ecosystem process when shredders are absent or present low abundance in streams affected by urbanization. Finally, we summarize important implications in terms of managing of native vegetation and riparian buffers to promote ecological integrity and functioning of tropical Andean stream ecosystems.

Fungal community composition in neotropical rain forests: the influence of tree diversity and precipitation.

PubMed

McGuire, Krista L; Fierer, Noah; Bateman, Carling; Treseder, Kathleen K; Turner, Benjamin L

2012-05-01

Plant diversity is considered one factor structuring soil fungal communities because the diversity of compounds in leaf litter might determine the extent of resource heterogeneity for decomposer communities. Lowland tropical rain forests have the highest plant diversity per area of any biome. Since fungi are responsible for much of the decomposition occurring in forest soils, understanding the factors that structure fungi in tropical forests may provide valuable insight for predicting changes in global carbon and nitrogen fluxes. To test the role of plant diversity in shaping fungal community structure and function, soil (0-20 cm) and leaf litter (O horizons) were collected from six established 1-ha forest census plots across a natural plant diversity gradient on the Isthmus of Panama. We used 454 pyrosequencing and phospholipid fatty acid analysis to evaluate correlations between microbial community composition, precipitation, soil nutrients, and plant richness. In soil, the number of fungal taxa increased significantly with increasing mean annual precipitation, but not with plant richness. There were no correlations between fungal communities in leaf litter and plant diversity or precipitation, and fungal communities were found to be compositionally distinct between soil and leaf litter. To directly test for effects of plant species richness on fungal diversity and function, we experimentally re-created litter diversity gradients in litter bags with 1, 25, and 50 species of litter. After 6 months, we found a significant effect of litter diversity on decomposition rate between one and 25 species of leaf litter. However, fungal richness did not track plant species richness. Although studies in a broader range of sites is required, these results suggest that precipitation may be a more important factor than plant diversity or soil nutrient status in structuring tropical forest soil fungal communities.

Leaf litter quality affects aquatic insect emergence: contrasting patterns from two foundation trees.

PubMed

Compson, Zacchaeus G; Adams, Kenneth J; Edwards, Joeseph A; Maestas, Jesse M; Whitham, Thomas G; Marks, Jane C

2013-10-01

Reciprocal subsidies between rivers and terrestrial habitats are common where terrestrial leaf litter provides energy to aquatic invertebrates while emerging aquatic insects provide energy to terrestrial predators (e.g., birds, lizards, spiders). We examined how aquatic insect emergence changed seasonally with litter from two foundation riparian trees, whose litter often dominates riparian streams of the southwestern United States: Fremont (Populus fremontii) and narrowleaf (Populus angustifolia) cottonwood. P. fremontii litter is fast-decomposing and lower in defensive phytochemicals (i.e., condensed tannins, lignin) relative to P. angustifolia. We experimentally manipulated leaf litter from these two species by placing them in leaf enclosures with emergence traps attached in order to determine how leaf type influenced insect emergence. Contrary to our initial predictions, we found that packs with slow-decomposing leaves tended to support more emergent insects relative to packs with fast-decomposing leaves. Three findings emerged. Firstly, abundance (number of emerging insects m(-2) day(-1)) was 25% higher on narrowleaf compared to Fremont leaves for the spring but did not differ in the fall, demonstrating that leaf quality from two dominant trees of the same genus yielded different emergence patterns and that these patterns changed seasonally. Secondly, functional feeding groups of emerging insects differed between treatments and seasons. Specifically, in the spring collector-gatherer abundance and biomass were higher on narrowleaf leaves, whereas collector-filterer abundance and biomass were higher on Fremont leaves. Shredder abundance and biomass were higher on narrowleaf leaves in the fall. Thirdly, diversity (Shannon's H') was higher on Fremont leaves in the spring, but no differences were found in the fall, showing that fast-decomposing leaves can support a more diverse, complex emergent insect assemblage during certain times of the year. Collectively, these results challenge the notion that leaf quality is a simple function of decomposition, suggesting instead that aquatic insects benefit differentially from different leaf types, such that some use slow-decomposing litter for habitat and its temporal longevity and others utilize fast-decomposing litter with more immediate nutrient release.

Tracking senescence-induced patterns in leaf litter leachate using parallel factor analysis (PARAFAC) modeling and self-organizing maps

NASA Astrophysics Data System (ADS)

Wheeler, K. I.; Levia, D. F.; Hudson, J. E.

2017-09-01

In autumn, the dissolved organic matter (DOM) contribution of leaf litter leachate to streams in forested watersheds changes as trees undergo resorption, senescence, and leaf abscission. Despite its biogeochemical importance, little work has investigated how leaf litter leachate DOM changes throughout autumn and how any changes might differ interspecifically and intraspecifically. Since climate change is expected to cause vegetation migration, it is necessary to learn how changes in forest composition could affect DOM inputs via leaf litter leachate. We examined changes in leaf litter leachate fluorescent DOM (FDOM) from American beech (Fagus grandifolia Ehrh.) leaves in Maryland, Rhode Island, Vermont, and North Carolina and from yellow poplar (Liriodendron tulipifera L.) leaves from Maryland. FDOM in leachate samples was characterized by excitation-emission matrices (EEMs). A six-component parallel factor analysis (PARAFAC) model was created to identify components that accounted for the majority of the variation in the data set. Self-organizing maps (SOM) compared the PARAFAC component proportions of leachate samples. Phenophase and species exerted much stronger influence on the determination of a sample's SOM placement than geographic origin. As expected, FDOM from all trees transitioned from more protein-like components to more humic-like components with senescence. Percent greenness of sampled leaves and the proportion of tyrosine-like component 1 were found to be significantly different between the two genetic beech clusters, suggesting differences in photosynthesis and resorption. Our results highlight the need to account for interspecific and intraspecific variations in leaf litter leachate FDOM throughout autumn when examining the influence of allochthonous inputs to streams.

[Contribution of soil fauna to the mass loss of Betula albosinensis leaf litter at early decomposition stage of subalpine forest litter in western Sichuan].

PubMed

Xia, Lei; Wu, Fu-Zhong; Yang, Wan-Qin; Tan, Bo

2012-02-01

In order to quantify the contribution of soil fauna to the decomposition of birch (Betula albosinensis) leaf litter in subalpine forests in western Sichuan of Southwest China during freeze-thaw season, a field experiment with different mesh sizes (0.02, 0.125, 1 and 3 mm) of litterbags was conducted in a representative birch-fir (Abies faxoniana) forest to investigate the mass loss rate of the birch leaf litter from 26 October, 2010 to 18 April, 2011, and the contributions of micro-, meso- and macro-fauna to the decomposition of the leaf litter. Over the freeze-thaw season, 11.8%, 13.2%, 15.4% and 19.5% of the mass loss were detected in the litterbags with 0.02, 0. 125, 1 and 3 mm mesh sizes, respectively. The total contribution of soil fauna to the litter decomposition accounted for 39.5% of the mass loss, and the taxa and individual relative density of the soil fauna in the litterbags had the similar variation trend with that of the mass loss rate. The contribution rate of soil fauna to the leaf litter mass loss showed the order of micro- < meso- < macro-fauna, with the highest contribution of micro-fauna (7.9%), meso-fauna (11.9%), and macro-fauna (22.7%) at the onset of freezing stage, deeply frozen stage, and thawing stage, respectively. The results demonstrated that soil fauna played an important role in the litter decomposition in subalpine forests of western Sichuan during freeze-thaw season.

Factors influencing leaf litter decomposition: An intersite decomposition experiment across China

USGS Publications Warehouse

Zhou, G.; Guan, L.; Wei, X.; Tang, X.; Liu, S.; Liu, J.; Zhang, Dongxiao; Yan, J.

2008-01-01

The Long-Term Intersite Decomposition Experiment in China (hereafter referred to as LTIDE-China) was established in 2002 to study how substrate quality and macroclimate factors affect leaf litter decomposition. The LTIDE-China includes a wide variety of natural and managed ecosystems, consisting of 12 forest types (eight regional broadleaf forests, three needle-leaf plantations and one broadleaf plantation) at eight locations across China. Samples of mixed leaf litter from the south subtropical evergreen broadleaf forest in Dinghushan (referred to as the DHS sample) were translocated to all 12 forest types. The leaf litter from each of other 11 forest types was placed in its original forest to enable comparison of decomposition rates of DHS and local litters. The experiment lasted for 30 months, involving collection of litterbags from each site every 3 months. Our results show that annual decomposition rate-constants, as represented by regression fitted k-values, ranged from 0.169 to 1.454/year. Climatic factors control the decomposition rate, in which mean annual temperature and annual actual evapotranspiration are dominant and mean annual precipitation is subordinate. Initial C/N and N/P ratios were demonstrated to be important factors of regulating litter decomposition rate. Decomposition process may apparently be divided into two phases controlled by different factors. In our study, 0.75 years is believed to be the dividing line of the two phases. The fact that decomposition rates of DHS litters were slower than those of local litters may have been resulted from the acclimation of local decomposer communities to extraneous substrate. ?? 2008 Springer Science+Business Media B.V.

[Evolution pattern of phytolith-occluded carbon in typical forest-soil ecosystems in tropics and subtropics, China.

PubMed

He, Shan Qiong; Huang, Zhang Ting; Wu, Jia Sen; Yang, Jie; Jiang, Pei Kun

2016-03-01

Samples of fresh leaves and leaf litter, as well as soils taken from 0-10 and 10-30 cm layers, were collected in four types of typical forest ecosystems both in subtropical (Phyllostachys pubescens, Pinus massoniana, Cycloba lanopsisglauca, and Cunninghamia lanceolata stands) and in tropical climates (Vatica mangachapoi, Musa basjoo, Heveabrasiliensis, and Acacia mangium stands) for measurement of PhytOC (phytolith-occluded organic carbon) contents. The phytoliths in both leaves and soil samples were extracted by a microwave digestion method and their PhytOC contents were determined by alkali dissolution-spectrophotometry method. It was found that, among the four types of subtropical forests, the PhytOC contents of leaves, litter and 0-10 cm soil layer were the highest in P. massoniana stand (230.24, 229.17 and 20.87 g·kg -1 ), the lowest in P. pubescens stand (30.55, 37.37, and 3.38 g·kg -1 ), and the PhytOC content of the 10-30 cm soil layer was the highest in C. glauca stand (18.54 g·kg -1 ), and the lowest in P. pubescens stand (2.90 g·kg -1 ). For the four tropical forests, A. mangium stand (377.66 g·kg -1 ) and V. mangachapoi stand (46.83 g·kg -1 ), respectively, deposited the highest and lowest contents of PhytOC in the leaves, while the highest and lowest contents of PhytOC in the litter were observed in H. brasiliensis stand (218.23 g·kg -1 ) and M. basjoo stand (27.66 g·kg -1 ), respectively. Also among the tropical forests, the highest PhytOC contents in the 0-10 cm and 10-30 cm soil layers were observed in A. mangium stand (23.84 and 24.90 g·kg -1 ), while the lowest values occurred in M. basjoo stand (3.89 and 3.93 g·kg -1 ). The PhytOC contents in transitioning from leaves to soils (0-10 cm layers) decreased by 97.4% for C. lanceolata, 94.9% for C. glauca, 90.9% for P. massoniana, and 88.9% for P. pubescens in the subtropics, and by 95.9% for H. brasiliensis, 93.7% for A. mangium, 93.3% for M. basjoo, 63.7% for V. mangachapoi in the tropics. There was no significant difference in PhytOC contents between leaves and litter for the following five forest types: P. pubescens, P. massoniana, C. lanceolata, V. mangachapoi and H. brasiliensis. However, significantly higher PhytOC contents in leaves than in litters were measured in C. glauca, M. basjoo, and A. mangium. The findings that significantly lower PhytOC contents occurred in soils than in fresh leaves and leaf litter regardless of type of forest ecosystem suggested that phytolith was not stable during the pathway from plants to soil via the forest litter.

Biodiversity hanging by a thread: the importance of fungal litter-trapping systems in tropical rainforests

PubMed Central

Snaddon, Jake L.; Turner, Edgar C.; Fayle, Tom M.; Khen, Chey V.; Eggleton, Paul; Foster, William A.

2012-01-01

The exceptionally high species richness of arthropods in tropical rainforests hinges on the complexity of the forest itself: that is, on features such as the high plant diversity, the layered nature of the canopy and the abundance and the diversity of epiphytes and litter. We here report on one important, but almost completely neglected, piece of this complex jigsaw—the intricate network of rhizomorph-forming fungi that ramify through the vegetation of the lower canopy and intercept falling leaf litter. We show that this litter-trapping network is abundant and intercepts substantial amounts of litter (257.3 kg ha−1): this exceeds the amount of material recorded in any other rainforest litter-trapping system. Experimental removal of this fungal network resulted in a dramatic reduction in both the abundance (decreased by 70.2 ± 4.1%) and morphospecies richness (decreased by 57.4 ± 5.1%) of arthropods. Since the lower canopy levels can contain the highest densities of arthropods, the proportion of the rainforest fauna dependent on the fungal networks is likely to be substantial. Fungal litter-trapping systems are therefore a crucial component of habitat complexity, providing a vital resource that contributes significantly to rainforest biodiversity. PMID:22188674

Leaf litter decomposition rates increase with rising mean annual temperature in Hawaiian tropical montane wet forests

Treesearch

Lori D. Bothwell; Paul C. Selmants; Christian P. Giardina; Creighton M. Litton

2014-01-01

Decomposing litter in forest ecosystems supplies nutrients to plants, carbon to heterotrophic soil microorganisms and is a large source of CO2 to the atmosphere. Despite its essential role in carbon and nutrient cycling, the temperature sensitivityof leaf litter decay in tropical forest ecosystems remains poorly resolved, especially in tropical...

Interaction of Substrate and Nutrient Availability on wood Biofilm Processes in Streams

Treesearch

Jennifer L. Tank; J.R. Webster

1998-01-01

We examined the effect of decomposing leaf litter and dissolved inorganic nutrients on the heterotrophic biofilm of submerged wood in streams with and without leaves. Leaf litter was excluded from one headwater stream in August 1993 at Coweeta Hydrologic Laboratory in the southern Appalachian Mountains. We compared microbial processes on wood in the litter-excluded...

Global synthesis of the temperature sensitivity of leaf litter breakdown in streams and rivers

Treesearch

Jennifer J. Follstad Shah; John S. Kominoski; Marcelo Ardón; Walter K. Dodds; Mark O. Gessner; Natalie A. Griffiths; Charles P. Hawkins; Sherri L. Johnson; Antoine Lecerf; Carri J. LeRoy; David W. P. Manning; Amy D. Rosemond; Robert L. Sinsabaugh; Christopher M. Swan; Jackson R. Webster; Lydia H. Zeglin

2017-01-01

Streams and rivers are important conduits of terrestrially derived carbon (C) to atmospheric and marine reservoirs. Leaf litter breakdown rates are expected to increase as water temperatures rise in response to climate change. The magnitude of increase in breakdown rates is uncertain, given differences in litter quality and microbial and detritivore community...

Transfer of radio-cesium from forest soil to woodchips using fungal activities

NASA Astrophysics Data System (ADS)

Kaneko, Nobuhiro; Huang, Yao; Tanaka, Yoichiro; Fujiwara, Yoshihiro; Sasaki, Michiko; Toda, Hiroto; Takahashi, Terumasa; Kobayashi, Tatsuaki; Harada, Naoki; Nonaka, Masahiro

2014-05-01

Raido-cesium released to terrestrial ecosystems by nuclear accidents is know to accumulate forest soil and organic layer on the soil. Forests in Japan are not exceptions. Practically it is impossible to decontaminate large area of forests. However, there is a strong demand from local people, who has been using secondary forests (Satoyama) around croplands in hilly areas, to decontaminate radio-cesium, because those people used to collect wild mushrooms and edible plants, and there are active cultures of mushrooms using logs and sawdusts. These natural resource uses consist substantial part of their economical activities, Therefore it is needed to decontaminate some selected part of forests in Japan to local economy. Clear cutting and scraping surface soil and organic matter are common methods of decontamination. However the efficiency of decontamination is up to 30% reduction of aerial radiation, and the cost to preserve contaminated debris is not affordable. In this study we used wood chips as a growth media for saprotrophic fungi which are known to accumulate redio-cesium. There are many studies indicated that mushrooms accumulated redio-cesium from forest soil and organic layer. It is not practical to collect mushrooms to decontaminate redio-cesium, because biomass of mushrooms are not enough to collect total contaminants. Mushrooms are only minor part of saprotrophic fungi. Fungal biomass in forest soil is about 1% of dead organic matter on forest floor. Our previous study to observe Cs accumulation to decomposing leaf litter indicated 18% absorption of total soil radio-Cs to litter during one year field incubation (Kaneko et al., 2013), and Cs concentration was proportional to fungal biomass on litter. This result indicated that fungi transferred radio-cesium around newly supplied leaf litter free of contamination. Therefore effective decontamination will be possible if we can provide large amount of growth media for saprotrophic fungi, and the media can be removed from forests with fungal bodies. We covered forest floor using wood chips, and observed Cs accumulation, and found that up to 50% of soil radio-cesium was transferred from soil to wood chips after 6-month of field incubation. Therefore this method is effective to decontaminate forest using ecological process. Kaneko N, Huang Y, Nakamori T, Tanaka Y, Nonaka M. Radio-cesium accumulation during decomposition of leaf litter in a deciduous forest after the Fukushima NPP accident. Geophysical Research Abstracts. 2013;15(EGU2013):7809.

Can species-specific differences in foliar chemistry influence leaf litter decomposition in grassland species?

NASA Astrophysics Data System (ADS)

Sanaullah, M.; Chabbi, A.; Rumpel, C.

2009-04-01

The influence of litter quality on its rate of decomposition is a crucial aspect of C cycle. In this study we concentrated on grassland ecosystems where leaf litter is one of the major sources of C input. To quantify the contribution of initial leaf chemistry within different plant species, the decomposition of chemically different leaf litter of three grassland species (Lolium perenne, Festuca arundinacea and Dactylis glomerata) was monitored, using the litter bag technique. Litter of different maturity stages i.e. green (fresh leaves) and brown litter (brown leaves were still attached to the plant), were incubated on bare soil surface. Samples were taken at different time intervals (0, 2, 4, 8, 20 and 44 weeks) and were analyzed for mass loss, organic C and N contents and stable isotopic signatures (C and N). Changes in litter chemistry were addressed by determining lignin-derived phenols after CuO oxidation and non-cellulosic polysaccharides after acid hydrolysis followed by gas chromatography. Green litter was chemically different from brown litter due to higher initial N and lower lignin contents. While in grassland species, both L. perenne and D. glomerata were similar in their initial chemical composition compared with F. arundinacea. Green litter showed higher rate of degradation. In green litter, Percent lignin remaining of initial (% OI) followed the similar decomposition pattern as of C remaining indicating lignin as controlling factor in decomposition. Constant Acid-to-Aldehyde ratios of lignin-derived phenols (vanillyl and syringyl) did not suggest any transformation in lignin structures. In green litter, increase in non-cellulosic polysaccharides ratios (C6/C5 and deoxy/C5) proposed microbial-derived sugars, while there was no significant increase in these ratios in brown litter. In conclusion, due to the differences in initial chemical composition (initial N and lignin contents), green litter decomposition was higher than brown litter in all grassland species. Regardless of similarities in initial composition of grassland species, green and brown litter of Lolium perenne decomposed more rapidly compared with other two species. So, Species related differences in initial litter chemistry did not control its degradation.

Experimental manipulation of leaf litter colonization by aquatic invertebrates in a third order tropical stream.

PubMed

Uieda, V S; Carvalho, E M

2015-05-01

Through a manipulative experiment, the colonization of leaf litter by invertebrates was investigated in two sections of a tropical stream (spatial scale) that differed in function of the canopy cover, one with the presence (closed area) and another without riparian vegetation (open area), during one month of the dry and one of the wet season (temporal scale). The work aimed to verify differences related to four variables: season, canopy cover, leaf type and leaf condition. Litter bags containing arboreal and herbaceous leaves (leaf type variable), non-conditioned and preconditioned (leaf condition variable) were placed at the bottom of the stream in each area (canopy cover variable) and season (dry and wet), and removed after 13-day colonization. The analysis of the remaining litter dry mass per leaf bag emphasizes differences related mainly to seasonality, canopy cover and leaf type, although leaf condition was also important when combined with those three factors. Comparing the abundance of invertebrates per treatment, there was a tendency of high predominance of Chironomidae during the dry season and greater taxa diversity and evenness during the wet season, when the water flow increase could alter the availability of microhabitats for local fauna. Even though canopy cover alone was not a significant source of variation in the abundance of invertebrates, the results showed a tendency of a combined effect of canopy cover with seasonality and leaf condition.

More of the same? In situ leaf and root decomposition rates do not vary between 80 native and nonnative deciduous forest species.

PubMed

Jo, Insu; Fridley, Jason D; Frank, Douglas A

2016-01-01

Invaders often have greater rates of production and produce more labile litter than natives. The increased litter quantity and quality of invaders should increase nutrient cycling through faster litter decomposition. However, the limited number of invasive species that have been included in decomposition studies has hindered the ability to generalize their impacts on decomposition rates. Further, previous decomposition studies have neglected roots. We measured litter traits and decomposition rates of leaves for 42 native and 36 nonnative woody species, and those of fine roots for 23 native and 25 nonnative species that occur in temperate deciduous forests throughout the Eastern USA. Among the leaf and root traits that differed between native and invasive species, only leaf nitrogen was significantly associated with decomposition rate. However, native and nonnative species did not differ systematically in leaf and root decomposition rates. We found that among the parameters measured, litter decomposer activity was driven by litter chemical quality rather than tissue density and structure. Our results indicate that litter decomposition rate per se is not a pathway by which forest woody invasive species affect North American temperate forest soil carbon and nutrient processes. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Effect of litter, leaf cover and cover of basal internodes of the dominant species Molinia caerulea on seedling recruitment and established vegetation

NASA Astrophysics Data System (ADS)

Janeček, Štěpán; Lepš, Jan

2005-09-01

The effects of litter removal, leaf cover of established plants and cover of basal internodes of a dominant species Molinia caerulea on seedling germination and the dynamics of established plants were studied in a field experiment in an oligotrophic wet meadow. Although the negative influence of litter on total seedling number and seedling species composition was non-significant, litter significantly affected the dynamics of the established vegetation and caused inhibition of total leaf cover development. The effects of total leaf cover of established plants on seedling establishment changed during the vegetation season. Whereas the effect of total leaf cover was positive at the start and in the middle of the vegetation season, at the end the total leaf cover negatively affected seedling establishment. Both total leaf cover and cover of basal internodes affected seedling composition. Effects of these two variables were statistically separable suggesting that they are based on different mechanisms. The response of seedling establishment to these factors was species specific and, consequently, our data support the hypothesis that that biotically generated spatial heterogeneity can promote species co-existence through the differentiation of species regeneration niches.

On the relationships between leaf-litter lignin and net primary productivity in tropical rain forests.

PubMed

Kitayama, Kanehiro; Suzuki, Shizuo; Hori, Masato; Takyu, Masaaki; Aiba, Shin-Ichiro; Majalap-Lee, Noreen; Kikuzawa, Kihachiro

2004-07-01

We investigated if tropical rainforest trees produced more-lignified leaves in less productive environments using forests on Mount Kinabalu, Borneo. Our investigation was based on two earlier suggestions that slower litter decomposition occurs under less productive forests and that trees under resource limitation invest a large amount of carbon as lignin as a defense substance to minimize the loss from herbivores. When nine forests at different altitudes (700-3100 m) and soil conditions (derived from sedimentary or ultrabasic rocks) but with the same gentle relief position were compared, the concentrations of leaf-litter lignin were positively correlated with litterfall rates and leaf-litter nitrogen concentrations. These patterns would be reinforced in intact leaves if the effects of resorption at the time of leaf shedding were taken into account, because greater magnitude of resorption of mobile elements but not of lignin would occur in less productive environments (i.e. dilution of lignin in intact leaves). These results did not support earlier suggestions to explain the variation of leaf-litter lignin. Instead, we suggest that lower lignin contents are adaptive to recycle minerals without retarding decomposition in less productive environments.

Topographic heterogeneity effect on the accumulation of Fukushima-derived radiocesium on forest floor driven by biologically mediated processes

NASA Astrophysics Data System (ADS)

Koarashi, Jun; Atarashi-Andoh, Mariko; Takeuchi, Erina; Nishimura, Syusaku

2014-10-01

The accident at the Fukushima Daiichi nuclear power plant caused serious radiocesium (137Cs) contamination of forest ecosystems located in mountainous and hilly regions with steep terrain. To understand topographic effects on the redistribution and accumulation of 137Cs on forest floor, we investigated the distribution of Fukushima-derived 137Cs in forest-floor litter layers on a steep hillslope in a Japanese deciduous forest in August 2013 (29 months after the accident). Both leaf-litter materials and litter-associated 137Cs were accumulated in large amounts at the bottom of the hillslope. At the bottom, a significant fraction (65%) of the 137Cs inventory was observed to be associated with newly shed and less degraded leaf-litter materials, with estimated mean ages of 0.5-1.5 years, added via litterfall after the accident. Newly emerged leaves were contaminated with Fukushima-derived 137Cs in May 2011 (two months after the accident) and 137Cs concentration in them decreased with time. However, the concentrations were still two orders of magnitude higher than the pre-accident level in 2013 and 2014. These observations are the first to show that 137Cs redistribution on a forested hillslope is strongly controlled by biologically mediated processes and continues to supply 137Cs to the bottom via litterfall at a reduced rate.

Effects of different types of conditioning on rates of leaf-litter shredding by Xiphocaris elongata, a Neotropical freshwater shrimp.

Treesearch

Todd A. Crowl; Vanessa Welsh; Tamara Heartsill Scalley

2006-01-01

Temperate headwater streams with closed canopies rely on inputs of terrestrially derived organic matter to provide the major energy basis for their food webs. Microbial colonization, or conditioning, makes leaf litter more nutritional and palatable to stream detritivores, but few studies have investigated the relative importance of litter source to macroshredders in...

Decomposition of Betula papyrifera leaf litter under the independent and interactive effects of elevated CO2 and O3

Treesearch

William F.J. Parsons; Richard L. Lindroth; James G. Bockheim

2004-01-01

Litter decay dynamics of paper birch (Betula papyrifera) were assessed at the Aspen free-air CO2 enrichment (FACE) facility in northern Wisconsin, USA. Leaf litter was decomposed for 12 months under factorial combinations of 360 vs. 560 µLCO2 L-1, crossed with 36 vs. 55 nLO...

Plant recruitment in a northern Arizona ponderosa pine forest: Testing seed- and leaf litter-limitation hypotheses (P-53)

Treesearch

Scott R. Abella

2008-01-01

Seed availability and leaf litter limit plant establishment in some ecosystems. To evaluate the hypothesis that these factors limit understory plant recruitment in Pinus ponderosa forests, I conducted a seeding and litter removal experiment at six thinned sites in the Fort Valley Experimental Forest, northern Arizona. Experimental seeding of four native species (...

Plant recruitment in a northern Arizona ponderosa pine forest: Testing seed- and leaf litter-limitation hypotheses

Treesearch

Scott R. Abella

2008-01-01

Seed availability and leaf litter limit plant establishment in some ecosystems. To evaluate the hypothesis that these factors limit understory plant recruitment in Pinus ponderosa forests, I conducted a seeding and litter removal experiment at six thinned sites in the Fort Valley Experimental Forest, northern Arizona. Experimental seeding of four native species (

Tea polyphenols dominate the short-term tea (Camellia sinensis) leaf litter decomposition*

PubMed Central

Fan, Dong-mei; Fan, Kai; Yu, Cui-ping; Lu, Ya-ting; Wang, Xiao-chang

2017-01-01

Polyphenols are one of the most important secondary metabolites, and affect the decomposition of litter and soil organic matter. This study aims to monitor the mass loss rate of tea leaf litter and nutrient release pattern, and investigate the role of tea polyphenols played in this process. High-performance liquid chromatography (HPLC) and classical litter bag method were used to simulate the decomposition process of tea leaf litter and track the changes occurring in major polyphenols over eight months. The release patterns of nitrogen, potassium, calcium, and magnesium were also determined. The decomposition pattern of tea leaf litter could be described by a two-phase decomposition model, and the polyphenol/N ratio effectively regulated the degradation process. Most of the catechins decreased dramatically within two months; gallic acid (GA), catechin gallate (CG), and gallocatechin (GC) were faintly detected, while others were outside the detection limits by the end of the experiment. These results demonstrated that tea polyphenols transformed quickly and catechins had an effect on the individual conversion rate. The nutrient release pattern was different from other plants which might be due to the existence of tea polyphenols. PMID:28124839

Tea polyphenols dominate the short-term tea (Camellia sinensis) leaf litter decomposition.

PubMed

Fan, Dong-Mei; Fan, Kai; Yu, Cui-Ping; Lu, Ya-Ting; Wang, Xiao-Chang

Polyphenols are one of the most important secondary metabolites, and affect the decomposition of litter and soil organic matter. This study aims to monitor the mass loss rate of tea leaf litter and nutrient release pattern, and investigate the role of tea polyphenols played in this process. High-performance liquid chromatography (HPLC) and classical litter bag method were used to simulate the decomposition process of tea leaf litter and track the changes occurring in major polyphenols over eight months. The release patterns of nitrogen, potassium, calcium, and magnesium were also determined. The decomposition pattern of tea leaf litter could be described by a two-phase decomposition model, and the polyphenol/N ratio effectively regulated the degradation process. Most of the catechins decreased dramatically within two months; gallic acid (GA), catechin gallate (CG), and gallocatechin (GC) were faintly detected, while others were outside the detection limits by the end of the experiment. These results demonstrated that tea polyphenols transformed quickly and catechins had an effect on the individual conversion rate. The nutrient release pattern was different from other plants which might be due to the existence of tea polyphenols.

SOA formation potential of emissions from soil and leaf litter

DOE PAGES

Faiola, Celia L.; VanderSchelden, Graham S.; Wen, Miao; ...

2013-12-13

Soil and leaf litter are significant global sources of small oxidized volatile organic compounds, VOCs (e.g., methanol and acetaldehyde). They may also be significant sources of larger VOCs that could act as precursors to secondary organic aerosol (SOA) formation. To investigate this, soil and leaf litter samples were collected from the University of Idaho Experimental Forest and transported to the laboratory. There, the VOC emissions were characterized and used to drive SOA formation via dark, ozone-initiated reactions. Monoterpenes dominated the emission profile with emission rates as high as 228 μg-C m –2 h –1. The composition of the SOA producedmore » was similar to biogenic SOA formed from oxidation of ponderosa pine emissions and α-pinene. Measured soil and litter monoterpene emission rates were compared with modeled canopy emissions. Results suggest surface soil and litter monoterpene emissions could range from 12 to 136% of canopy emissions in spring and fall. Furthermore, emissions from leaf litter may potentially extend the biogenic emissions season, contributing to significant organic aerosol formation in the spring and fall when reduced solar radiation and temperatures reduce emissions from living vegetation.« less

Fungal decomposers of leaf litter from an invaded and native mountain forest of NW Argentina.

PubMed

Fernandez, Romina Daiana; Bulacio, Natalia; Álvarez, Analía; Pajot, Hipólito; Aragón, Roxana

2017-09-01

The impact of plant species invasions on the abundance, composition and activity of fungal decomposers of leaf litter is poorly understood. In this study, we isolated and compared the relative abundance of ligninocellulolytic fungi of leaf litter mixtures from a native forest and a forest invaded by Ligustrum lucidum in a lower mountain forest of Tucuman, Argentina. In addition, we evaluated the relationship between the relative abundance of ligninocellulolytic fungi and properties of the soil of both forest types. Finally, we identified lignin degrading fungi and characterized their polyphenol oxidase activities. The relative abundance of ligninocellulolytic fungi was higher in leaf litter mixtures from the native forest. The abundance of cellulolytic fungi was negatively related with soil pH while the abundance of ligninolytic fungi was positively related with soil humidity. We identified fifteen genera of ligninolytic fungi; four strains were isolated from both forest types, six strains only from the invaded forest and five strains were isolated only from the native forest. The results found in this study suggest that L. Lucidum invasion could alter the abundance and composition of fungal decomposers. Long-term studies that include an analysis of the nutritional quality of litter are needed, for a more complete overview of the influence of L. Lucidum invasion on fungal decomposers and on leaf litter decomposition.

Sympodial bamboo species differ in carbon bio-sequestration and stocks within phytoliths of leaf litters and living leaves.

PubMed

Xiang, Tingting; Ying, Yuqi; Teng, Jiangnan; Huang, Zhangting; Wu, Jiasen; Meng, Cifu; Jiang, Peikun; Tang, Caixian; Li, Jianmin; Zheng, Rong

2016-10-01

Phytolith-occluded carbon (PhytOC) with high resistance against decomposition is an important carbon (C) sink in many ecosystems. This study compared concentrations of phytolith in plants and the PhytOC production of seven sympodial bamboo species in southern China, aiming to provide the information for the managed bamboo plantation and selection of bamboo species to maximize phytolith C sequestration. Leaf litters and living leaves of seven sympodial bamboo species were collected from the field sites. Concentrations of phytoliths, silicon (Si), and PhytOC in leaf litters and living leaves were measured. Carbon sequestration as PhytOC was estimated. There was a considerable variation in the PhytOC concentrations in the leaf litters and living leaves among the seven bamboo species. The mean concentrations of PhytOC ranged from 3.4 to 6.9 g kg(-1) in leaf litters and from 1.6 to 5.9 g kg(-1) in living leaves, with the PhytOC production rates ranging from 5.7 to 52.3 kg e-CO2 ha(-1) year(-1) as leaf litters. Dendrocalamopsis oldhami (Munro) Keng f. had the highest PhytOC production rate. Based on a bio-sequestration rate of 52.3 kg e-CO2 ha(-1) year(-1), we estimated that the current 8 × 10(5) ha of sympodial bamboo stands in China could potentially acquire 4.2 × 10(4) t e-CO2 yearly via phytolith carbon. Furthermore, the seven sympodial bamboo species stored 5.38 × 10(5) t e-CO2 as PhytOC in living leaves and leaf litters in China. It is concluded that sympodial bamboos make a significant contribution to C sequestration and that to maximize the PhytOC accumulation, the bamboo species with the highest PhytOC production rate should be selected for plantation.

Leaf Litter Mixtures Alter Microbial Community Development: Mechanisms for Non-Additive Effects in Litter Decomposition

PubMed Central

Chapman, Samantha K.; Newman, Gregory S.; Hart, Stephen C.; Schweitzer, Jennifer A.; Koch, George W.

2013-01-01

To what extent microbial community composition can explain variability in ecosystem processes remains an open question in ecology. Microbial decomposer communities can change during litter decomposition due to biotic interactions and shifting substrate availability. Though relative abundance of decomposers may change due to mixing leaf litter, linking these shifts to the non-additive patterns often recorded in mixed species litter decomposition rates has been elusive, and links community composition to ecosystem function. We extracted phospholipid fatty acids (PLFAs) from single species and mixed species leaf litterbags after 10 and 27 months of decomposition in a mixed conifer forest. Total PLFA concentrations were 70% higher on litter mixtures than single litter types after 10 months, but were only 20% higher after 27 months. Similarly, fungal-to-bacterial ratios differed between mixed and single litter types after 10 months of decomposition, but equalized over time. Microbial community composition, as indicated by principal components analyses, differed due to both litter mixing and stage of litter decomposition. PLFA biomarkers a15∶0 and cy17∶0, which indicate gram-positive and gram-negative bacteria respectively, in particular drove these shifts. Total PLFA correlated significantly with single litter mass loss early in decomposition but not at later stages. We conclude that litter mixing alters microbial community development, which can contribute to synergisms in litter decomposition. These findings advance our understanding of how changing forest biodiversity can alter microbial communities and the ecosystem processes they mediate. PMID:23658639

Predator-prey pursuit-evasion games in structurally complex environments.

PubMed

Morice, Sylvie; Pincebourde, Sylvain; Darboux, Frédéric; Kaiser, Wilfried; Casas, Jérôme

2013-11-01

Pursuit and evasion behaviors in many predator-prey encounters occur in a geometrically structured environment. The physical structures in the environment impose strong constraints on the perception and behavioral responses of both antagonists. Nevertheless, no experimental or theoretical study has tackled the issue of quantifying the role of the habitat's architecture on the joint trajectories during a predator-prey encounter. In this study, we report the influence of microtopography of forest leaf litter on the pursuit-evasion trajectories of wolf spiders Pardosa sp. attacking the wood cricket Nemobius sylvestris. Fourteen intact leaf litter samples of 1 m × 0.5 m were extracted from an oak-beech forest floor in summer and winter, with later samples having the most recently fallen leaves. Elevation was mapped at a spatial resolution of 0.5 mm using a laser scanner. Litter structuring patterns were identified by height transects and experimental semi-variograms. Detailed analysis of all visible leaf-fragments of one sample enabled us to relate the observed statistical patterns to the underlying geometry of individual elements. Video recording of pursuit-evasion sequences in arenas with flat paper or leaf litter enabled us to estimate attack and fleeing distances as a function of substrate. The compaction index, the length of contiguous flat surfaces, and the experimental variograms showed that the leaf litter was smoother in summer than in winter. Thus, weathering as well as biotic activities compacted and flattened the litter over time. We found good agreement between the size of the structuring unit of leaf litter and the distance over which attack and escape behaviors both were initiated (both ∼3 cm). There was a four-fold topographical effect on pursuit-escape sequences; compared with a flat surface, leaf litter (1) greatly reduced the likelihood of launching a pursuit, (2) reduced pursuit and escape distances by half, (3) put prey and predator on par in terms of pursuit and escape distances, and (4) reduced the likelihood of secondary pursuits, after initial escape of the prey, to nearly zero. Thus, geometry of the habitat strongly modulates the rules of pursuit-evasion in predator-prey interactions in the wild.

Production and decomposition of forest litter fall on the Apalachicola River flood plain, Florida: Chapter B, Apalachicola River quality assessment

USGS Publications Warehouse

Elder, John F.; Cairns, Duncan J.

1982-01-01

Measurements of litter fall (leaves and other particulate organic material) and leaf decomposition were made on the bottom-land hardwood swamp of the Apalachicola River flood plain in 1979-80. Litter fall was collected monthly from nets located in 16 study plots. The plots represented five forest types in the swamp and levee areas of the Apalachicola River flood plain. Forty-three species of trees, vines, and other plants contributed to the total litter fall, but more than 90 percent of the leaf material originated from 12 species. Nonleaf material made up 42 percent of the total litter fall. Average litter fall was determined to be 800 grams per square meter per year, resulting in an annual deposition of 3.6 ? 105 metric tons of organic material in the 454-square-kilometer flood plain. The levee communities have less tree biomass but greater tree diversity than do swamp communities. The levee vegetation, containing less tree biomass, produces slightly more litter fall per unit of ground surface area than does the swamp vegetation. The swamps are dominated by three genera: tupelo (Nyssa), cypress (Taxodium) and ash (Fraxinus). These genera account for more than 50 percent of the total leaf fall in the flood plain, but they are the least productive, on a weight-perbiomass basis, of any of the 12 major leaf producers. Decomposition rates of leaves from five common floodplain tree species were measured using a standard leaf-bag technique. Leaf decomposition was highly species dependent. Tupelo (Nyssa spp.) and sweetgum (Liquidambar styraciflua) leaves decomposed completely in 6 months when flooded by river water. Leaves of baldcypress (Taxodium distichum) and diamond-leaf oak (Quercus laurifolia) were much more resistant. Water hickory (Carya aquatica) leaves showed intermediate decomposition rates. Decomposition of all species was greatly reduced in dry environments. Carbon and biomass loss rates from the leaves were nearly linear over a 6-month period, but nitrogen and phosphorus leaching was nearly complete within 1 month. Much of the organic substance may be recycled in the forest ecosystem, but annual flooding of the river provides an important mechanism for mobilization of the litter-fall products.

Phosphorus availability modulates the toxic effect of silver on aquatic fungi and leaf litter decomposition.

PubMed

Funck, J Arce; Clivot, H; Felten, V; Rousselle, P; Guérold, F; Danger, M

2013-11-15

The functioning of forested headwater streams is intimately linked to the decomposition of leaf litter by decomposers, mainly aquatic hyphomycetes, which enables the transfer of allochthonous carbon to higher trophic levels. Evaluation of this process is being increasingly used as an indicator of ecosystem health and ecological integrity. Yet, even though the individual impacts of contaminants and nutrient availability on decomposition have been well studied, the understanding of their combined effects remains limited. In the current study, we investigated whether the toxic effects of a reemerging contaminant, silver (Ag), on leaf litter decomposition could be partly overcome in situations where microorganisms were benefitting from high phosphorus (P) availability, the latter being a key chemical element that often limits detritus decomposition. We also investigated whether these interactive effects were mediated by changes in the structure of the aquatic hyphomycete community. To verify these hypotheses, leaf litter decomposition by a consortium of ten aquatic hyphomycete species was followed in a microcosm experiment combining five Ag contamination levels and three P concentrations. Indirect effects of Ag and P on the consumption of leaf litter by the detritivorous crustacean, Gammarus fossarum, were also evaluated. Ag significantly reduced decomposition but only at the highest concentration tested, independently of P level. By contrast, P and Ag interactively affected fungal biomass. Both P level and Ag concentrations shaped microbial communities without significantly affecting the overall species richness. Finally, the levels of P and Ag interacted significantly on G. fossarum feeding rates, high [Ag] reducing litter consumption and low P availability tending to intensify the feeding rate. Given the high level of contaminant needed to impair the decomposition process, it is unlikely that a direct effect of Ag on leaf litter decomposition could be observed in situ. However, subtle Ag effects in relation to nutrient levels in ecosystems could be expected. In particular, owing to higher consumption of low P leaf litter, shredding invertebrates could increase the ingestion of contaminated resources, which could, in turn, represent an important threat to headwater stream ecosystems. Copyright © 2013 Elsevier B.V. All rights reserved.

[Relationships between decomposition rate of leaf litter and initial quality across the alpine timberline ecotone in Western Sichuan, China].

PubMed

Yang, Lin; Deng, Chang-chun; Chen Ya-mei; He, Run-lian; Zhang, Jian; Liu, Yang

2015-12-01

The relationships between litter decomposition rate and their initial quality of 14 representative plants in the alpine forest ecotone of western Sichuan were investigated in this paper. The decomposition rate k of the litter ranged from 0.16 to 1.70. Woody leaf litter and moss litter decomposed much slower, and shrubby litter decomposed a little faster. Then, herbaceous litters decomposed fastest among all plant forms. There were significant linear regression relationships between the litter decomposition rate and the N content, lignin content, phenolics content, C/N, C/P and lignin/N. Lignin/N and hemicellulose content could explain 78.4% variation of the litter decomposition rate (k) by path analysis. The lignin/N could explain 69.5% variation of k alone, and the direct path coefficient of lignin/N on k was -0.913. Principal component analysis (PCA) showed that the contribution rate of the first sort axis to k and the decomposition time (t) reached 99.2%. Significant positive correlations existed between lignin/N, lignin content, C/N, C/P and the first sort axis, and the closest relationship existed between lignin/N and the first sort axis (r = 0.923). Lignin/N was the key quality factor affecting plant litter decomposition rate across the alpine timberline ecotone, with the higher the initial lignin/N, the lower the decomposition rate of leaf litter.

Production of litter and detritus related to the density of mangrove

NASA Astrophysics Data System (ADS)

Budi Mulya, Miswar; Arlen, HJ

2018-03-01

Research about the production of leaf litter and detritus related to the density of mangrove trees has been done. The aims of this research are to know and analyze the amount of litter and detritus produced to the density of mangrove trees. The production and collection of leaf litter were carried out in five stations. Production of detritus and decomposition rate were calculated by measuring its dry weight. The density and level of mangrove trees were determined using transect quadratic method. The relationship between the leaf litter and detritus production ratio related to mangrove density were then analyzed. Results showed that mangrove trees with the density of 766.67 ind ha‑1 ccould produce the amount of litter and detritus to about 28597.33 gha‑1day‑1and 1099.35 gha‑1day‑1 while mangrove trees with the density of 1300 ind ha‑1 could produce the amount of litter and detritus to about 35093.33 g/ha/day and 1216.68 gha‑1day‑1 respectively. Data analysis showed that the increment of mangrove density is linearly related to the production increment of litter and detritus.

Correlation of foliage and litter chemistry of sugar maple, Acer saccharum, as affected by elevated CO2 and varying N availability, and effects on decomposition

Treesearch

J. S. King; K. S. Pregitzer; D. R. Zak; M. E. Kubiske; W. E. Holmes

2001-01-01

Rising atmospheric carbon dioxide has the potential to alter leaf litter chemistry, potentially affecting decomposition and rates of carbon and nitrogen cycling in forest ecosystems. This study was conducted to determine whether growth under elevated atmospheric CO2 altered the quality and microbial decomposition of leaf litter of a widely...

Long-term patterns of mass loss during the decomposition of leaf and fine root litter: an intersite comparison

Treesearch

Mark E. Harmon; Whendee L. Silver; Becky Fasth; Hua Chen; Ingrid C. Burke; William J. Parton; Stephen C. Hart; William S. Currie; Ariel E. Lugo

2009-01-01

Decomposition is a critical process in global carbon cycling. During decomposition, leaf and fine root litter may undergo a later, relatively slow phase; past long-term experiments indicate this phase occurs, but whether it is a general phenomenon has not been examined. Data from Long-term Intersite Decomposition Experiment Team, representing 27 sites and nine litter...

Intrapopulation Genotypic Variation of Foliar Secondary Chemistry during Leaf Senescence and Litter Decomposition in Silver Birch (Betula pendula)

PubMed Central

Paaso, Ulla; Keski-Saari, Sarita; Keinänen, Markku; Karvinen, Heini; Silfver, Tarja; Rousi, Matti; Mikola, Juha

2017-01-01

Abundant secondary metabolites, such as condensed tannins, and their interpopulation genotypic variation can remain through plant leaf senescence and affect litter decomposition. Whether the intrapopulation genotypic variation of a more diverse assortment of secondary metabolites equally persists through leaf senescence and litter decomposition is not well understood. We analyzed concentrations of intracellular phenolics, epicuticular flavonoid aglycones, epicuticular triterpenoids, condensed tannins, and lignin in green leaves, senescent leaves and partly decomposed litter of silver birch, Betula pendula. Broad-sense heritability (H2) and coefficient of genotypic variation (CVG) were estimated for metabolites in senescent leaves and litter using 19 genotypes selected from a B. pendula population in southern Finland. We found that most of the secondary metabolites remained through senescence and decomposition and that their persistence was related to their chemical properties. Intrapopulation H2 and CVG for intracellular phenolics, epicuticular flavonoid aglycones and condensed tannins were high and remarkably, increased from senescent leaves to decomposed litter. The rank of genotypes in metabolite concentrations was persistent through litter decomposition. Lignin was an exception, however, with a diminishing genotypic variation during decomposition, and the concentrations of lignin and condensed tannins had a negative genotypic correlation in the senescent leaves. Our results show that secondary metabolites and their intrapopulation genotypic variation can for the most part remain through leaf senescence and early decomposition, which is a prerequisite for initial litter quality to predict variation in litter decomposition rates. Persistent genotypic variation also opens an avenue for selection to impact litter decomposition in B. pendula populations through acting on their green foliage secondary chemistry. The negative genotypic correlations and diminishing heritability of lignin concentrations may, however, counteract this process. PMID:28694813

Intrapopulation Genotypic Variation of Foliar Secondary Chemistry during Leaf Senescence and Litter Decomposition in Silver Birch (Betula pendula).

PubMed

Paaso, Ulla; Keski-Saari, Sarita; Keinänen, Markku; Karvinen, Heini; Silfver, Tarja; Rousi, Matti; Mikola, Juha

2017-01-01

Abundant secondary metabolites, such as condensed tannins, and their interpopulation genotypic variation can remain through plant leaf senescence and affect litter decomposition. Whether the intrapopulation genotypic variation of a more diverse assortment of secondary metabolites equally persists through leaf senescence and litter decomposition is not well understood. We analyzed concentrations of intracellular phenolics, epicuticular flavonoid aglycones, epicuticular triterpenoids, condensed tannins, and lignin in green leaves, senescent leaves and partly decomposed litter of silver birch, Betula pendula . Broad-sense heritability ( H 2 ) and coefficient of genotypic variation ( CV G ) were estimated for metabolites in senescent leaves and litter using 19 genotypes selected from a B. pendula population in southern Finland. We found that most of the secondary metabolites remained through senescence and decomposition and that their persistence was related to their chemical properties. Intrapopulation H 2 and CV G for intracellular phenolics, epicuticular flavonoid aglycones and condensed tannins were high and remarkably, increased from senescent leaves to decomposed litter. The rank of genotypes in metabolite concentrations was persistent through litter decomposition. Lignin was an exception, however, with a diminishing genotypic variation during decomposition, and the concentrations of lignin and condensed tannins had a negative genotypic correlation in the senescent leaves. Our results show that secondary metabolites and their intrapopulation genotypic variation can for the most part remain through leaf senescence and early decomposition, which is a prerequisite for initial litter quality to predict variation in litter decomposition rates. Persistent genotypic variation also opens an avenue for selection to impact litter decomposition in B. pendula populations through acting on their green foliage secondary chemistry. The negative genotypic correlations and diminishing heritability of lignin concentrations may, however, counteract this process.

Mixing effects on litter decomposition rates in a young tree diversity experiment

NASA Astrophysics Data System (ADS)

Setiawan, Nuri Nurlaila; Vanhellemont, Margot; De Schrijver, An; Schelfhout, Stephanie; Baeten, Lander; Verheyen, Kris

2016-01-01

Litter decomposition is an essential process for biogeochemical cycling and for the formation of new soil organic matter. Mixing litter from different tree species has been reported to increase litter decomposition rates through synergistic effects. We assessed the decomposition rates of leaf litter from five tree species in a recently established tree diversity experiment on a post-agriculture site in Belgium. We used 20 different leaf litter compositions with diversity levels ranging from 1 up to 4 species. Litter mass loss in litterbags was assessed 10, 20, 25, 35, and 60 weeks after installation in the field. We found that litter decomposition rates were higher for high-quality litters, i.e., with high nitrogen content and low lignin content. The decomposition rates of mixed litter were more affected by the identity of the litter species within the mixture than by the diversity of the litter per se, but the variability in litter decomposition rates decreased as the litter diversity increased. Among the 15 different mixed litter compositions in our study, only three litter combinations showed synergistic effects. Our study suggests that admixing tree species with high-quality litter in post-agricultural plantations helps in increasing the mixture's early-stage litter decomposition rate.

Algorithm for retrieving vegetative canopy and leaf parameters from multi- and hyperspectral imagery

NASA Astrophysics Data System (ADS)

Borel, Christoph

2009-05-01

In recent years hyper-spectral data has been used to retrieve information about vegetative canopies such as leaf area index and canopy water content. For the environmental scientist these two parameters are valuable, but there is potentially more information to be gained as high spatial resolution data becomes available. We developed an Amoeba (Nelder-Mead or Simplex) based program to invert a vegetative canopy radiosity model coupled with a leaf (PROSPECT5) reflectance model and modeled for the background reflectance (e.g. soil, water, leaf litter) to a measured reflectance spectrum. The PROSPECT5 leaf model has five parameters: leaf structure parameter Nstru, chlorophyll a+b concentration Cab, carotenoids content Car, equivalent water thickness Cw and dry matter content Cm. The canopy model has two parameters: total leaf area index (LAI) and number of layers. The background reflectance model is either a single reflectance spectrum from a spectral library() derived from a bare area pixel on an image or a linear mixture of soil spectra. We summarize the radiosity model of a layered canopy and give references to the leaf/needle models. The method is then tested on simulated and measured data. We investigate the uniqueness, limitations and accuracy of the retrieved parameters on canopy parameters (low, medium and high leaf area index) spectral resolution (32 to 211 band hyperspectral), sensor noise and initial conditions.

Decomposition and nitrogen dynamics of 15N-labeled leaf, root, and twig litter in temperate coniferous forests

USGS Publications Warehouse

van Huysen, Tiff L.; Harmon, Mark E.; Perakis, Steven S.; Chen, Hua

2013-01-01

Litter nutrient dynamics contribute significantly to biogeochemical cycling in forest ecosystems. We examined how site environment and initial substrate quality influence decomposition and nitrogen (N) dynamics of multiple litter types. A 2.5-year decomposition study was installed in the Oregon Coast Range and West Cascades using 15N-labeled litter from Acer macrophyllum, Picea sitchensis, and Pseudotsuga menziesii. Mass loss for leaf litter was similar between the two sites, while root and twig litter exhibited greater mass loss in the Coast Range. Mass loss was greatest from leaves and roots, and species differences in mass loss were more prominent in the Coast Range. All litter types and species mineralized N early in the decomposition process; only A. macrophyllum leaves exhibited a net N immobilization phase. There were no site differences with respect to litter N dynamics despite differences in site N availability, and litter N mineralization patterns were species-specific. For multiple litter × species combinations, the difference between gross and net N mineralization was significant, and gross mineralization was 7–20 % greater than net mineralization. The mineralization results suggest that initial litter chemistry may be an important driver of litter N dynamics. Our study demonstrates that greater amounts of N are cycling through these systems than may be quantified by only measuring net mineralization and challenges current leaf-based biogeochemical theory regarding patterns of N immobilization and mineralization.

Formation of Soil Water Repellency by Laboratory Burning and Its Effect on Soil Evaporation

NASA Astrophysics Data System (ADS)

Ahn, Sujung; Im, Sangjun

2010-05-01

Fire-induced soil water repellency can vary with burning conditions, and may lead to significant changes in soil hydraulic properties. However, isolation of the effects of soil water repellency from other factors is difficult, particularly under field conditions. This study was conducted to (i) investigate the effects of burning using different plant leaf materials and (ii) of different burning conditions on the formation of soil water repellency, and (iii) isolate the effects of the resulting soil water repellency on soil evaporation from other factors. Burning treatments were performed on the surface of homogeneous fully wettable sand soil contained in a steel frame (60 x 60 cm; 40 cm depth). As controls a sample without a heat treatment, and a heated sample without fuel, were also used. Ignition and heat treatments were carried out with a gas torch. For comparing the effects of different burning conditions, fuel types included oven-dried pine needles (fresh needles of Pinus densiflora), pine needle litter (litter on a coniferous forest floor, P. densiflora + P. rigida), and broad-leaf litter (Quercus mongolica + Q. aliena + Prunus serrulata var. spontanea + other species); fuel loads were 200 g, 300 g, and 500 g; and heating duration was 40 s, 90 s and 180 s. The heating duration was adjusted to control the temperature, based on previous experiments. The temperature was measured continuously at 3-second intervals and logged with two thermometers. After burning, undisturbed soil columns were sampled for subsequent experiments. Water Drop Penetration Time (WDPT) test was performed at every 1 mm depth of the soil columns to measure the severity of soil water repellency and its vertical extent. Soil water repellency was detected following all treatments. As the duration of heating increased, the thickness of the water repellent layer increased, whilst the severity of soil water repellency decreased. As regards fuel amount, the most severe soil water repellency was formed at a fuel load of 300 g. Pine needle litter formed the most severe soil water repellency and fresh pine needle formed the thickest water repellent layer, whilst broad-leaf litter did only cause water repellency on the surface of the sand. The soil evaporation rate was measured by a gravitational method at an isothermal condition. Undisturbed soil columns were sealed after adding 50 ml of tap water through the bottom. After twelve hours of stabilization, the columns were opened and covered with filter paper. The rate of soil evaporation through the soil surface was measured by the hourly weight change at 45° C. The initial 65 hours' evaporation rate was analyzed, while the slope of cumulative evaporation over time maintained its linearity. It was found that as the thickness of the water repellent layer increased, the evaporation rate tended to decrease. These two variables showed a good correlation (Pearson's correlation coefficient =-0.8916, p=0.0170) and a large coefficient of determination (R2=0.795) in the linear regression. This suggests that a layer of water repellent soil can affect water evaporation rate and that the rate is negatively correlated with the thickness of the repellent layer.

[Litter decomposition and its main affecting factors in tidal marshes of Minjiang River Estuary, East China].

PubMed

Zhang, Lin-Hai; Zeng, Cong-Sheng; Zhang, Wen-Juan; Wang, Tian-E; Tong, Chuan

2012-09-01

By using litterbag method, this paper studied the decomposition of the leaf- and flower litters of two emergent macrophytes, native species Phragmites australis and invasive species Spartina alterniflora, and related affecting factors in the Minjiang River estuary of East China. In the decomposition process of the litters, the decay of standing litter (0-90 days) was an important period, and the loss rate of the flower- and leaf litters dry mass of P. australis and S. alterniflora was 15.0 +/- 3.5% and 13.3 +/- 1.1%, and 31.9 +/- 1.1% and 20.8 +/- 1.4%, respectively. During lodging decay period (91-210 days), the loss rate of the flower- and leaf litters dry mass of P. australis and S. alterniflora was 69.5 +/- 0.6% and 71.5 +/- 2.5%, and 76.8 +/- 1.9% and 67.5 +/- 2.1%, respectively. In standing decay period, the decomposition rate of the two plants litters was positively correlated with the litters C/N but negatively correlated to the litters N/P, and the litters P was an important factor limiting the litters decay. In lodging decay period, the effects of the litters C/N, C/P, and N/P decreased, while the environment factors (climate, soil moisture, soil acidity and salinity, and sediment properties) acted more important roles. The differences in the factors affecting the decay of the litters in different decomposition periods were mainly related to the micro-environment and tidal process for the two plant communities.

CO2 enrichment and N addition increase nutrient loss from decomposing leaf litter in subtropical model forest ecosystems

PubMed Central

Liu, Juxiu; Fang, Xiong; Deng, Qi; Han, Tianfeng; Huang, Wenjuan; Li, Yiyong

2015-01-01

As atmospheric CO2 concentration increases, many experiments have been carried out to study effects of CO2 enrichment on litter decomposition and nutrient release. However, the result is still uncertain. Meanwhile, the impact of CO2 enrichment on nutrients other than N and P are far less studied. Using open-top chambers, we examined effects of elevated CO2 and N addition on leaf litter decomposition and nutrient release in subtropical model forest ecosystems. We found that both elevated CO2 and N addition increased nutrient (C, N, P, K, Ca, Mg and Zn) loss from the decomposing litter. The N, P, Ca and Zn loss was more than tripled in the chambers exposed to both elevated CO2 and N addition than those in the control chambers after 21 months of treatment. The stimulation of nutrient loss under elevated CO2 was associated with the increased soil moisture, the higher leaf litter quality and the greater soil acidity. Accelerated nutrient release under N addition was related to the higher leaf litter quality, the increased soil microbial biomass and the greater soil acidity. Our results imply that elevated CO2 and N addition will increase nutrient cycling in subtropical China under the future global change. PMID:25608664

Fusarium equiseti LPSC 1166 and its in vitro role in the decay of Heterostachys ritteriana leaf litter.

PubMed

Franco, Ernesto; Troncozo, María I; Baez, Margot; Mirífico, María V; Robledo, Gerardo L; Balatti, Pedro A; Saparrat, Mario C N

2018-03-01

The role of microorganisms in litter degradation in arid and semi-arid zones, where soil and water salinization is one of the main factors limiting carbon turnover and decay, remains obscure. Heterostachys ritteriana (Amaranthaceae), a halophyte shrub growing in arid environments such as "Salinas Grandes" (Córdoba, Argentina), appears to be the main source of organic matter in the area. Little is known regarding the microorganisms associated with H. ritteriana, although they are a potential source of enzymes such as cellulolytic ones, which might be important in biotechnological fields such as bioethanol production using ionic liquids. In the present study, by studying the microbiota growing on H. ritteriana leaf litter in "Salinas Grandes," we isolated the cellulolytic fungus Fusarium equiseti LPSC 1166, which grew and degraded leaf litter under salt stress. The growth of this fungus was a function of the C substrate and the presence of NaCl. Although in vitro the fungus used both soluble and polymeric compounds from H. ritteriana litter and synthesized extracellular β-1,4 endoglucanases, its activity was reduced by 10% NaCl. Based on these results, F. equiseti LPSC 1166 can be described as a halotolerant cellulolytic fungus most probably playing a key role in the decay of H. ritteriana leaf litter in "Salinas Grandes."

Recent (<4 year old) Leaf Litter is Not a Major Source of Microbial Carbon in a Temperate Forest Mineral Soil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kramer, Christiane; Trumbore, Susan E.; Froberg, Mats J.

2010-01-01

Microbial communities in soil A horizons derive their carbon from several potential sources: organic carbon (C) transported down from overlying litter and organic horizons, root-derived C, or soil organic matter. We took advantage of a multi-year experiment that manipulated the {sup 14}C isotope signature of surface leaf litter inputs in a temperate forest at the Oak Ridge Reservation, Tennessee, USA, to quantify the contribution of recent leaf litter C to microbial respiration and biomarkers in the underlying mineral soil. We observed no measurable difference (< {approx}40{per_thousand} given our current analytical methods) in the radiocarbon signatures of microbial phospholipid fatty acidsmore » (PLFA) isolated from the top 10 cm of mineral soil in plots that experienced 3 years of litterfall that differed in each year by {approx}750{per_thousand} between high-{sup 14}C and low-{sup 14}C treatments. Assuming any difference in {sup 14}C between the high- and low-{sup 14}C plots would reflect C derived from these manipulated litter additions, we estimate that <6% of the microbial C after 4 years was derived from the added 1-4-year-old surface litter. Large contributions of C from litter < 1 year (or >4 years) old (which fell after (or prior to) the manipulation and therefore did not differ between plots) are not supported because the {sup 14}C signatures of the PLFA compounds (averaging 200-220{per_thousand}) is much higher that of the 2004-5 leaf litter (115{per_thousand}) or pre-2000 litter. A mesocosm experiment further demonstrated that C leached from {sup 14}C-enriched surface litter or the O horizon was not a detectable C source in underlying mineral soil microbes during the first eight months after litter addition. Instead a decline in the {sup 14}C of PLFA over the mesocosm experiment likely reflected the loss of a pre-existing substrate not associated with added leaf litter. Measured PLFA {Delta}{sup 14}C signatures were higher than those measured in bulk mineral soil organic matter in our experiments, but fell within the range of {sup 14}C values measured in mineral soil roots. Together, our experiments suggest that root-derived C is the major (>60%) source of C for microbes in these temperate deciduous forest soils.« less

Leaf litter dynamics and nitrous oxide emission in a Mediterranean riparian forest: implications for soil nitrogen dynamics.

PubMed

Bernal, S; Butturini, A; Nin, E; Sabater, F; Sabater, S

2003-01-01

Mediterranean riparian zones can experience severe drought periods that lead to low soil moisture content, which dramatically affects their performance as nitrate removal systems. In the Mediterranean riparian zone of this study, we determined that N2O emission was practically nil. To understand the role of forest floor processes in nitrogen retention of a Mediterranean riparian area, we studied leaf litter dynamics of two tree species, London planetree [Platanus x acerifolia (Aiton) Willd.] and alder [Alnus glutinosa (L.) Gaertn.], for two years, along with soil nitrogen mineralization rates. Annual leaf litter fall equaled 562.6 +/- 10.1 (standard error) g dry wt. m(-2), 68% of which was planetree and 32% of which was alder. The temporal distribution of litterfall showed a two-peak annual cycle, one occurring in midsummer, the other in autumn. Planetree provided the major input of organic nitrogen to the forest floor, and the amount of planetree leaves remaining on the forest floor was equivalent to approximately four years of stock. Leaf litter decomposition was three times higher for alder (decay coefficient [k] = 1.13 yr(-1)) than for planetree (k = 0.365 yr(-1)). Mineralization rates showed a seasonal pattern, with the maximum rate in summer (1.92 mg N kg(-1) d(-1)). Although the forest floor was an important sink for nitrogen due to planetree leaf accumulation, 7.5% of this leaf litter was scoured to the streambed by wind. This loss was irrelevant for alder leaves. Due to the litter quality, the forest floor of this Mediterranean riparian forest acts as a nitrogen sink.

Effect of inorganic nutrients on relative contributions of fungi and bacteria to carbon flow from submerged decomposing leaf litter

Treesearch

Vladislav Gulis; Keller Suberkropp

2003-01-01

The relative contributions of fungi and bacteria to carbon flow from submerged decaying plant litter at different levels of inorganic nutrients (N and P) were studied. We estimated leaf mass loss, fungal and bacterial biomass and production, and microbial respiration and constructed partial carbon budgets for red maple leaf disks precolonized in a stream and then...

Monitoring Phytophthora ramorum in soil, leaf litter, rain traps, and watercourses in an historical cornish garden

Treesearch

David Lockley; Judith Turner; Gillian Humphries; Phil Jennings

2008-01-01

Phytophthora ramorum was identified as the cause of a leaf blight on rhododendrons in an historic garden in Cornwall in 2003. A programme of measures was set in place to eradicate the disease from the garden and several sites were selected to monitor the effect of these measures on the recovery of P. ramorum from soil, leaf litter...

Monoterpene concentrations in fresh, senescent, and decaying foliage of singleleaf pinyon (Pinus monophylla Torr. & Frem.: Pinaceae) from the western Great Basin.

PubMed

Wilt, F M; Miller, G C; Everett, R L; Hackett, M

1993-02-01

Senescent foliage from pines is potentially a large contributor to the total monoterpene content of the litter layer, and the availability of these compounds as phytotoxins may result from release of these compounds into the vapor phase. In order to determine the fate of several monoterpene hydrocarbons in the natural environment, we examined their concentrations in fresh, senescent, and decaying needles from 32 single-leaf pinyon pine (Pinus monophylla Torr. & Frem.: Pinaceae) trees growing at two different locations. Total monoterpene content was highest in the fresh needles (mean=5.6 ± 2.2 mg/g extracted air dry weight), but also remained relatively high in senescent needles (mean=3.6 ±1.8 mg/g extracted air dry weight), either still attached to the tree or forming the freshest layer of understory litter. Decaying needles within a dark decomposing layer of litter material 5-20 cm from the surface were found to contain much lower amounts of total monoterpenes (average: =0.12 ±0.06 mg/g extracted air dry weight). Further investigation of the fate of these compounds in the pinyon understory is required to determine if these hydrocarbons are indeed exerting phytotoxic characteristics.

Effects of pyrolysis temperature, time and leaf litter and powder coal ash addition on sludge-derived adsorbents for nitrogen oxide.

PubMed

Ren, Xiaoli; Liang, Baohong; Liu, Min; Xu, Xiaoyuan; Cui, Meihua

2012-12-01

The objective of this research was to seek a cost effective solution to prepare adsorbents for nitrogen oxide from surplus sludge. Leaf litter and powder coal ash were used as cheap and easily available additives. An adsorbent for nitrogen oxide was prepared by pyrolysis of dried sludge mixed with zinc chloride. Under optimum pyrolysis conditions of 375°C for 90 min and a zinc chloride content of 30%, the surface area of the adsorbent with leaf litter was 514.41 m(2)/g, the surface area of the adsorbent with powder coal ash was 432.34 m(2)/g, respectively, corresponding to an increase of 90.70% and 60.27% when compared to the adsorbent without the additives. The saturated adsorption quantity of the adsorbent with leaf litter reached 271 mg/g at 20°C. The results indicated that the sludge-derived adsorbent was quite promising for nitrogen oxide removal. Copyright © 2012 Elsevier Ltd. All rights reserved.

Invasive species' leaf traits and dissimilarity from natives shape their impact on nitrogen cycling: a meta-analysis.

PubMed

Lee, Marissa R; Bernhardt, Emily S; van Bodegom, Peter M; Cornelissen, J Hans C; Kattge, Jens; Laughlin, Daniel C; Niinemets, Ülo; Peñuelas, Josep; Reich, Peter B; Yguel, Benjamin; Wright, Justin P

2017-01-01

Many exotic species have little apparent impact on ecosystem processes, whereas others have dramatic consequences for human and ecosystem health. There is growing evidence that invasions foster eutrophication. We need to identify species that are harmful and systems that are vulnerable to anticipate these consequences. Species' traits may provide the necessary insights. We conducted a global meta-analysis to determine whether plant leaf and litter functional traits, and particularly leaf and litter nitrogen (N) content and carbon: nitrogen (C : N) ratio, explain variation in invasive species' impacts on soil N cycling. Dissimilarity in leaf and litter traits among invaded and noninvaded plant communities control the magnitude and direction of invasion impacts on N cycling. Invasions that caused the greatest increases in soil inorganic N and mineralization rates had a much greater litter N content and lower litter C : N in the invaded than the reference community. Trait dissimilarities were better predictors than the trait values of invasive species alone. Quantifying baseline community tissue traits, in addition to those of the invasive species, is critical to understanding the impacts of invasion on soil N cycling. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Litter P content drives consumer production in detritus-based streams spanning an experimental N:P gradient.

PubMed

Demi, Lee M; Benstead, Jonathan P; Rosemond, Amy D; Maerz, John C

2018-02-01

Ecological stoichiometry theory (EST) is a key framework for predicting how variation in N:P supply ratios influences biological processes, at molecular to ecosystem scales, by altering the availability of C, N, and P relative to organismal requirements. We tested EST predictions by fertilizing five forest streams at different dissolved molar N:P ratios (2, 8, 16, 32, 128) for two years and tracking responses of macroinvertebrate consumers to the resulting steep experimental gradient in basal resource stoichiometry (leaf litter %N, %P, and N:P). Nitrogen and P content of leaf litter, the dominant basal resource, increased in all five streams following enrichment, with steepest responses in litter %P and N:P ratio. Additionally, increases in primary consumer biomass and production occurred in all five streams following N and P enrichment (averages across all streams: biomass by 1.2×, production by 1.6×). Patterns of both biomass and production were best predicted by leaf litter N:P and %P and were unrelated to leaf litter %N. Primary consumer production increased most in streams where decreases in leaf litter N:P were largest. Macroinvertebrate predator biomass and production were also strongly positively related to litter %P, providing robust experimental evidence for the primacy of P limitation at multiple trophic levels in these ecosystems. However, production of predatory macroinvertebrates was not related directly to primary consumer production, suggesting the importance of additional controls for macroinvertebrates at upper trophic positions. Our results reveal potential drivers of animal production in detritus-based ecosystems, including the relative importance of resource quality vs. quantity. Our study also sheds light on the more general impacts of variation in N:P supply ratio on nutrient-poor ecosystems, providing strong empirical support for predictions that nutrient enrichment increases food web productivity whenever large elemental imbalances between basal resources and consumer demand are reduced. © 2017 by the Ecological Society of America.

Photobleaching Kinetics of Chromophoric Dissolved Organic Matter Derived from Mangrove Leaf Litter and Floating Sargassum Colonies

EPA Science Inventory

We examined the photoreactivity of chromophoric dissolved organic matter (CDOM) derived from Rhizophora mangle (red mangrove) leaf litter and floating Sargassum colonies as these marine plants can be important contributors to coastal and open ocean CDOM pools, respectively. Mangr...

Tadpoles of Early Breeding Amphibians are Negatively Affected by Leaf Litter From Invasive Chinese Tallow Trees

NASA Astrophysics Data System (ADS)

Leonard, N. E.

2005-05-01

As wetlands are invaded by Chinese tallow trees (Triadica sebifera), native trees are displaced and detrital inputs to amphibian breeding ponds are altered. I used a mesocosm experiment to examine the effect of Chinese tallow leaf litter on the survival to, size at, and time to metamorphosis of amphibian larvae. Fifty 1000-L cattle watering tanks were treated with 1500 g dry weight of one of five leaf litter treatments: Chinese tallow, laurel oak (Quercus laurifolia), water tupelo (Nyssa aquatica), slash pine (Pinus elliottii), or a 3:1:1:1 mixture. Each tank received 45 tadpoles of Pseudacris feriarum, Bufo terrestris, and Hyla cinerea in sequence according to their natural breeding phonologies. Every Pseudacris feriarum and Bufo terrestris tadpole exposed to Chinese tallow died prior to metamorphosis. Hyla cinerea survival in tanks with tallow-only was significantly lower than that observed for all other leaf treatments. Hyla cinerea tadpoles from tallow-only and mixed-leaf treatments were larger at metamorphosis and transformed faster than those in tanks with native leaves only. These results suggest that Chinese tallow leaf litter may negatively affect tadpoles of early breeding frogs and that Chinese tallow invasion may change the structure of amphibian communities in temporary ponds.

The importance of leaf- and litter-feeding invertebrates as sources of animal protein for the Amazonian Amerindians.

PubMed

Paoletti, M G; Dufour, D L; Cerda, H; Torres, F; Pizzoferrato, L; Pimentel, D

2000-11-22

At least 32 Amerindian groups in the Amazon basin use terrestrial invertebrates as food. Leaf- and litter-consuming invertebrates provide the more important, underestimated food sources for many Amerindian groups. Further, litter-consuming earthworms are also an important food resource for the Ye'Kuana (also known as Makiritare) in the Alto Orinoco (Amazonas, Venezuela). By selecting these small invertebrates the Amerindians are choosing their animal food from those food webs in the rainforest which have the highest energy flow and which constitute the greatest renewable stock of readily available nutrients. Here we show that the consumption of leaf- and litter-feeding invertebrates as a means of recovering protein, fat and vitamins by the forest-living peoples offers a new perspective for the development of sustainable animal food production within the paradigm of biodiversity maintenance.

Genotype × Herbivore Effect on Leaf Litter Decomposition in Betula Pendula Saplings: Ecological and Evolutionary Consequences and the Role of Secondary Metabolites

PubMed Central

Silfver, Tarja; Paaso, Ulla; Rasehorn, Mira; Rousi, Matti; Mikola, Juha

2015-01-01

Plant genetic variation and herbivores can both influence ecosystem functioning by affecting the quantity and quality of leaf litter. Few studies have, however, investigated the effects of herbivore load on litter decomposition at plant genotype level. We reduced insect herbivory using an insecticide on one half of field-grown Betula Pendula saplings of 17 genotypes, representing random intrapopulation genetic variation, and allowed insects to naturally colonize the other half. We hypothesized that due to induced herbivore defence, saplings under natural herbivory produce litter of higher concentrations of secondary metabolites (terpenes and soluble phenolics) and have slower litter decomposition rate than saplings under reduced herbivory. We found that leaf damage was 89 and 53% lower in the insecticide treated saplings in the summer and autumn surveys, respectively, which led to 73% higher litter production. Litter decomposition rate was also affected by herbivore load, but the effect varied from positive to negative among genotypes and added up to an insignificant net effect at the population level. In contrast to our hypothesis, concentrations of terpenes and soluble phenolics were higher under reduced than natural herbivory. Those genotypes, whose leaves were most injured by herbivores, produced litter of lowest mass loss, but unlike we expected, the concentrations of terpenes and soluble phenolics were not linked to either leaf damage or litter decomposition. Our results show that (1) the genetic and herbivore effects on B. pendula litter decomposition are not mediated through variation in terpene or soluble phenolic concentrations and suggest that (2) the presumably higher insect herbivore pressure in the future warmer climate will not, at the ecological time scale, affect the mean decomposition rate in genetically diverse B. pendula populations. However, (3) due to the significant genetic variation in the response of decomposition to herbivory, evolutionary changes in mean decomposition rate are possible. PMID:25622034

CDOM PRODUCTION BY MANGROVE LEAF LITTER AND SARGASSUM COLONIES IN FLORIDA KEYS COASTAL WATERS

EPA Science Inventory

We have investigated the importance of leaf litter from red mangroves (Rhizophora mangle) and living Sargassum plants as sources of chromophoric dissolved organic matter (CDOM) to the coastal ocean waters and coral reef system of the Florida Keys. The magnitude of UVB exposure t...

Inhibition of forage seed germination by leaf litter extracts of overstory hardwoods used in silvopastoral systems

USDA-ARS?s Scientific Manuscript database

Silvopastoral management strategies seek to expand spatial and temporal boundaries of forage production and promote ecosystem integrity through a combination of tree thinning and understory pastures. We determined the effects of water extracts of leaf litter from yellow poplar, Liriodendron tulipife...

Andersonoplatus, a new, remarkable, leaf litter inhabiting genus of Monoplatina (Coleoptera: Chrysomelidae: Galerucinae: Alticini)

USDA-ARS?s Scientific Manuscript database

Andersonoplatus, new genus with 16 new species from Venezuela and Panama is described and illustrated. All the specimens are collected in leaf litter by R. Anderson and S. and J. Peck. Andersonoplatus is compared to Andersonaltica Linzmeier and Konstantinov, Apleuraltica Bechyne, Distigmoptera Blake...

Leaf litter decomposition in Torna stream before and after a red mud disaster.

PubMed

Kucserka, T; Karádi-Kovács, Kata; Vass, M; Selmeczy, G B; Hubai, Katalin Eszter; Üveges, Viktória; Kacsala, I; Törő, N; Padisák, Judit

2014-03-01

The aim of the study was to estimate the breakdown of the allochthonous litter in an artificial stream running in an agricultural area and compare it with the same values following a toxic mud spill into the same stream. Litter bags were filled with three types of leaves (Quercus robur, Populus tremula and Salix alba) and placed to the bottom of the river. Ergosterol was used to detect fungal biomass. We supposed the absence of fungi and the retardation of leaf litter decomposition. Only pH and conductivity increased significantly. Leaf mass loss after the catastrophe was much slower than in 2009 and the decay curves did not follow the exponential decay model. Prior to the catastrophe, leaf mass loss was fast in Torna, compared to other streams in the area. The reason is that the stream is modified, the bed is trapezoid and covered with concrete stones. Fungal biomass was lower, than in the pre-disaster experiment, because fungi did not have enough leaves to sporulate. Leaf mass loss followed the exponential decay curve before the disaster, but after that it was possible only after a non-change period.

Impact of an Alien Invasive Shrub on Ecology of Native and Alien Invasive Mosquito Species (Diptera: Culicidae).

PubMed

Muturi, Ephantus J; Gardner, Allison M; Bara, Jeffrey J

2015-10-01

We examined how leaf litter of alien invasive honeysuckle (Lonicera maackii Rupr.) either alone or in combination with leaf litter of one of two native tree species, sugar maple (Acer saccharum Marshall) and northern red oak (Quercus rubra L.), affects the ecology of Culex restuans Theobald, Ochlerotatus triseriatus Say, and Ochlerotatus japonicus Theobald. Experimental mesocosms containing single species litter or a mixture of honeysuckle and one of two native tree species litter were established at South Farms and Trelease Woods study sites in Urbana, IL, and examined for their effect on 1) oviposition site selection by the three mosquito species, and 2) adult production and body size of Oc. triseriatus and Oc. japonicus. There were no significant effects of study site and leaf treatment on Oc. japonicus and Oc. triseriatus oviposition preference and adult production. In contrast, significantly more Cx. restuans eggs rafts were collected at South Farms relative to Trelease Woods and in honeysuckle litter relative to native tree species litter. Significantly larger adult females of Oc. japonicus and Oc. triseriatus were collected at South Farms relative to Trelease Woods and in honeysuckle litter relative to native tree species litter. Combining honeysuckle litter with native tree species litter had additive effects on Cx. restuans oviposition preference and Oc. japonicus and Oc. triseriatus body size, with the exception of honeysuckle and northern red oak litter combination, which had antagonistic effects on Oc. triseriatus body size. We conclude that input of honeysuckle litter into container aquatic habitats may alter the life history traits of vector mosquito species. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Soil respiration and aboveground litter dynamics of a tropical transitional forest in northwest Mato Grosso, Brazil

NASA Astrophysics Data System (ADS)

Valentini, Carla Maria Abido; Sanches, Luciana; de Paula, Sérgio Roberto; Vourlitis, George Louis; de Souza Nogueira, José; Pinto, Osvaldo Borges; de Almeida Lobo, Francisco

2008-12-01

Measurements of soil CO2 efflux, litter production, and the surface litter pool biomass were made over a 1 year period in a tropical transitional forest near Sinop, Mato Grosso, Brazil with the aim of quantifying the seasonal variation in soil respiration and litter decomposition and the annual contribution of litter decomposition to soil CO2 efflux. Average annual soil CO2 efflux (+/-95% confidence interval (CI)) was 7.91 +/- 1.16 g C m-2 d-1. Soil CO2 efflux was highest during the November-February wet season (9.15 +/- 0.90 g C m-2 d-1) and lowest during the May-September dry season (6.19 +/- 1.40 g C m-2 d-1), and over 60% of the variation in seasonal soil CO2 efflux was explained by seasonal variations in soil temperature and moisture. Mass balance estimates of mean (+/-95% CI) decomposition rates were statistically different between the wet and dry seasons (0.66 +/- 0.08 and 1.65 +/- 0.10 g C m-2 d-1, respectively), and overall, decomposition of leaf litter comprised 16% of the average annual soil respiration. Leaf litter production was higher during the dry season, and mean (+/-95% CI) leaf litter fall (5.6 +/- 1.7 Mg ha-1) comprised 73% of the total litter fall (7.8 +/- 2.3 Mg ha-1). Average (+/-95% CI) annual litter pool biomass was estimated to be 5.5 +/- 0.3 Mg ha-1, which was similar to the measured pool size (5.7 +/- 2.2 Mg ha-1). Overall, seasonal variations in environmental variables, specifically water availability (soil moisture and rainfall), had a profound influence on litter production, soil respiration, and surface litter decomposition.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mack, R.N.

Artemisia tridentata on the A. tridentata-Agropyron spicatum habitat type (h.t.) annually sheds approximately 117 kg/ha of leaf and inflorescence litter as determined by collecting litter of shrubs enclosed in nylon net cages. Total available amounts of cations (kg/ha) to a depth of 1 m on this h.t. are Ca, 21,936; Mg, 4450; P, 127.2; and K, 3588. On the adjacent A. tridentata-Poa secunda h.t., approximately /sup 1///sub 2/ of the leaf litter is lost in the 1st year on the soil surface with an element mobility series of K > Mg > P = Ca. Inflorescence litter apparently decays completelymore » within 6 months after abscission.« less

Toxicity evaluation of a conservation effects assessment program watershed, Beasley Lake, in the Mississippi Delta, USA

USDA-ARS?s Scientific Manuscript database

Beasley Lake was assessed monthly in 2005 for biological impairment from 17 historic and current-use pesticides in water and leaf litter using Hyalella azteca (Saussure). Sixteen pesticides were detected in both water and leaf litter with peak detections in spring and summer. Detections ranged fro...

Impacts of elevated CO2 and O3 on aspen leaf litter chemistry and earthworm and springtail productivity

Treesearch

Timothy D. Meehan; Michael S. Crossley; Richard L. Lindroth

2010-01-01

Human alteration of atmospheric composition affects foliar chemistry and has possible implications for the structure and functioning of detrital communities. In this study, we explored the impacts of elevated carbon dioxide and ozone on aspen (Populus tremuloides) leaf litter chemistry, earthworm (Lumbricus terrestris) individual...

Decomposition of Metrosideros polymorpha leaf litter along elevational gradients in Hawaii

Treesearch

Paul G. Scowcroft; Douglas R. Turner; Peter M. Vitousek

2000-01-01

We examined interactions between temperature, soil development, and decomposition on three elevational gradients, the upper and lower ends of each being situated on a common lava flow or ash deposit. We used the reciprocal transplant technique to estimate decomposition rates of Metrosideros polymorpha leaf litter during a three-year period at warm...

Shelters of leaf-tying herbivores decompose faster than leaves damaged by free-living insects: Implications for nutrient turnover in polluted habitats.

PubMed

Kozlov, Mikhail V; Zverev, Vitali; Zvereva, Elena L

2016-10-15

Leaf-eating insects can influence decomposition processes by modifying quality of leaf litter, and this impact can be especially pronounced in habitats where leaf-eating insects reach high densities, for example in heavily polluted areas. We hypothesized that the decomposition rate is faster for shelters of leaf-tying larvae than for leaves damaged by free-living insects, in particular due to the accumulation of larval frass within shelters. We exposed litter bags containing samples of three different compositions (shelters built by moth larvae, leaves damaged by free-living insects and intact leaves of mountain birch, Betula pubescens ssp. czerepanovii) for one year at two heavily polluted sites near the nickel-copper smelter at Monchegorsk in north-western Russia and at two unpolluted sites. The decomposition rate of leaves damaged by free-living insects was 91% of that of undamaged leaves, whereas the mass loss of leaves composing shelters did not differ of that of undamaged leaves. These differences between leaves damaged by different guilds of herbivorous insects were uniform across the study sites, although the decomposition rate in polluted sites was reduced to 77% of that in unpolluted sites. Addition of larval frass to undamaged leaves had no effect on the subsequent decomposition rate. Therefore we suggest that damaged leaves tied by shelter-building larvae decompose faster than untied damaged leaves due to a looser physical structure of the litter, which creates favourable conditions for detritivores and soil decomposers. Thus, while leaf damage by insects per se reduces litter quality and its decomposition rate, structuring of litter by leaf-tying insects counterbalances these negative effects. We conclude that leaf-tying larvae, in contrast to free-living defoliators, do not impose negative effects on nutrient turnover rate even at their high densities, which are frequently observed in heavily polluted sites. Copyright © 2016 Elsevier B.V. All rights reserved.

Movement analyses of wood cricket ( Nemobius sylvestris) (Orthoptera: Gryllidae).

PubMed

Brouwers, N C; Newton, A C

2010-12-01

Information on the dispersal ability of invertebrate species associated with woodland habitats is severely lacking. Therefore, a study was conducted examining the movement patterns of wood cricket (Nemobius sylvestris) (Orthoptera: Gryllidae) on the Isle of Wight, UK. Juvenile (i.e. nymphs) and adult wood crickets were released and observed over time within different ground surface substrates. Their movement paths were recorded and subsequently analysed using random walk models. Nymphs were found to move more slowly than adults did; and, when given a choice, both nymphs and adults showed a preference for moving through or over leaf litter compared to bare soil or grass. A correlated random walk (CRW) model accurately described the movement pattern of adult wood crickets through leaf litter, indicating a level of directional persistence in their movements. The estimated population spread through leaf litter for adults was 17.9 cm min-1. Movements of nymphs through leaf litter could not accurately be described by a random walk model, showing a change in their movement pattern over time from directed to more random movements. The estimated population spread through leaf litter for nymphs was 10.1 cm min-1. The results indicate that wood cricket adults can be considered as more powerful dispersers than nymphs; however, further analysis of how the insects move through natural heterogeneous environments at a range of spatio-temporal scales needs to be performed to provide a complete understanding of the dispersal ability of the species.

Microhabitats and canopy cover moderate high summer temperatures in a fragmented Mediterranean landscape.

PubMed

Keppel, Gunnar; Anderson, Sharolyn; Williams, Craig; Kleindorfer, Sonia; O'Connell, Christopher

2017-01-01

Extreme heat events will become more frequent under anthropogenic climate change, especially in Mediterranean ecosystems. Microhabitats can considerably moderate (buffer) the effects of extreme weather events and hence facilitate the persistence of some components of the biodiversity. We investigate the microclimatic moderation provided by two important microhabitats (cavities formed by the leaves of the grass-tree Xanthorrhoea semiplana F.Muell., Xanthorrhoeaceae; and inside the leaf-litter) during the summer of 2015/16 on the Fleurieu Peninsula of South Australia. We placed microsensors inside and outside these microhabitats, as well as above the ground below the forest canopy. Grass-tree and leaf-litter microhabitats significantly buffered against high temperatures and low relative humidity, compared to ground-below-canopy sensors. There was no significant difference between grass-tree and leaf-litter temperatures: in both microhabitats, daily temperature variation was reduced, day temperatures were 1-5°C cooler, night temperatures were 0.5-3°C warmer, and maximum temperatures were up to 14.4°C lower, compared to ground-below-canopy sensors. Grass-tree and leaf-litter microhabitats moderated heat increase at an average rate of 0.24°C temperature per 1°C increase of ambient temperature in the ground-below-canopy microhabitat. The average daily variation in temperature was determined by the type (grass-tree and leaf-litter versus ground-below-canopy) of microhabitat (explaining 67%), the amount of canopy cover and the area of the vegetation fragment (together explaining almost 10% of the variation). Greater canopy cover increased the amount of microclimatic moderation provided, especially in the leaf-litter. Our study highlights the importance of microhabitats in moderating macroclimatic conditions. However, this moderating effect is currently not considered in species distribution modelling under anthropogenic climate change nor in the management of vegetation. This shortcoming will have to be addressed to obtain realistic forecasts of future species distributions and to achieve effective management of biodiversity.

Potential Rapid Effects on Soil Organic Matter Characteristics and Chemistry Following a Change in Dominant Litter Inputs

NASA Astrophysics Data System (ADS)

Crow, S. E.; Filley, T.; Conyers, G.; Stott, D.; McCormick, M.; Whigham, D.; Taylor, D.

2006-12-01

Changes in vegetation structure are expected in forests globally under predicted future climate scenarios. Shifts in type or quantity of litter inputs, which will be associated with changes in plant community, may influence soil organic matter (SOM) characteristics. We altered litter inputs in a mixed-deciduous forest at the Smithsonian Environmental Research Center beginning in May 2004: litter removal, leaf amendment, and wood amendment plots were established in three old (120-150 y) and three young (50-70 y) forests. Plots were amended with wood and leaves collected locally from the dominant tree species, tulip poplar (Lirodendron tulipifera). 0-5 cm A horizon soil was collected in November 2005, 18 months after initial treatment, and physically fractionated first by dispersal in HMP and size separation (53 μm) to remove silts and clays then the >53 μm fraction by density (1.4 g cm-3) in SPT to separate the organic debris (light fraction, LF) from the mineral material. Soil with the greatest amount of C present within the LF came from the wood amendment treatment (35.2 ± 0.1%), followed by the leaf amendment (27.7 ± 0.0%) and the litter removal (24.5 ± 0.0%) treatments. In a pattern opposite of the other treatments, leaf amended soil from the old sites had less C within LF than the young. Potentially, a priming effect from the leaf addition at the old sites resulted in increased decomposition of soil LF. While at the young sites, invasive earthworms potentially provided a rapid, direct mode for incorporation of fresh leaf inputs into LF. Preliminary data indicate differences in lignin and cutin/suberin decay rates during litter decomposition between old and young sites. An investigation into the biopolymer composition of LF will determine whether altering litter inputs will ultimately influence SOM dynamics at both the old and young forest sites.

Changes in the structural composition and reactivity of Acer rubrum leaf litter tannins exposed to warming and altered precipitation: climatic stress-induced tannins are more reactive.

PubMed

Tharayil, Nishanth; Suseela, Vidya; Triebwasser, Daniella J; Preston, Caroline M; Gerard, Patrick D; Dukes, Jeffrey S

2011-07-01

• Climate change could increase the frequency with which plants experience abiotic stresses, leading to changes in their metabolic pathways. These stresses may induce the production of compounds that are structurally and biologically different from constitutive compounds. • We studied how warming and altered precipitation affected the composition, structure, and biological reactivity of leaf litter tannins in Acer rubrum at the Boston-Area Climate Experiment, in Massachusetts, USA. • Warmer and drier climatic conditions led to higher concentrations of protective compounds, including flavonoids and cutin. The abundance and structure of leaf tannins also responded consistently to climatic treatments. Drought and warming in combination doubled the concentration of total tannins, which reached 30% of leaf-litter DW. This treatment also produced condensed tannins with lower polymerization and a greater proportion of procyanidin units, which in turn reduced sequestration of tannins by litter fiber. Furthermore, because of the structural flexibility of these tannins, litter from this treatment exhibited five times more enzyme (β-glucosidase) complexation capacity on a per-weight basis. Warmer and wetter conditions decreased the amount of foliar condensed tannins. • Our finding that warming and drought result in the production of highly reactive tannins is novel, and highly relevant to climate change research as these tannins, by immobilizing microbial enzymes, could slow litter decomposition and thus carbon and nutrient cycling in a warmer, drier world. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.

Functional traits drive the contribution of solar radiation to leaf litter decomposition among multiple arid-zone species.

PubMed

Pan, Xu; Song, Yao-Bin; Liu, Guo-Fang; Hu, Yu-Kun; Ye, Xue-Hua; Cornwell, William K; Prinzing, Andreas; Dong, Ming; Cornelissen, Johannes H C

2015-08-18

In arid zones, strong solar radiation has important consequences for ecosystem processes. To better understand carbon and nutrient dynamics, it is important to know the contribution of solar radiation to leaf litter decomposition of different arid-zone species. Here we investigated: (1) whether such contribution varies among plant species at given irradiance regime, (2) whether interspecific variation in such contribution correlates with interspecific variation in the decomposition rate under shade; and (3) whether this correlation can be explained by leaf traits. We conducted a factorial experiment to determine the effects of solar radiation and environmental moisture for the mass loss and the decomposition constant k-values of 13 species litters collected in Northern China. The contribution of solar radiation to leaf litter decomposition varied significantly among species. Solar radiation accelerated decomposition in particular in the species that already decompose quickly under shade. Functional traits, notably specific leaf area, might predict the interspecific variation in that contribution. Our results provide the first empirical evidence for how the effect of solar radiation on decomposition varies among multiple species. Thus, the effect of solar radiation on the carbon flux between biosphere and atmosphere may depend on the species composition of the vegetation.

Functional traits drive the contribution of solar radiation to leaf litter decomposition among multiple arid-zone species

PubMed Central

Pan, Xu; Song, Yao-Bin; Liu, Guo-Fang; Hu, Yu-Kun; Ye, Xue-Hua; Cornwell, William K.; Prinzing, Andreas; Dong, Ming; Cornelissen, Johannes H.C.

2015-01-01

In arid zones, strong solar radiation has important consequences for ecosystem processes. To better understand carbon and nutrient dynamics, it is important to know the contribution of solar radiation to leaf litter decomposition of different arid-zone species. Here we investigated: (1) whether such contribution varies among plant species at given irradiance regime, (2) whether interspecific variation in such contribution correlates with interspecific variation in the decomposition rate under shade; and (3) whether this correlation can be explained by leaf traits. We conducted a factorial experiment to determine the effects of solar radiation and environmental moisture for the mass loss and the decomposition constant k-values of 13 species litters collected in Northern China. The contribution of solar radiation to leaf litter decomposition varied significantly among species. Solar radiation accelerated decomposition in particular in the species that already decompose quickly under shade. Functional traits, notably specific leaf area, might predict the interspecific variation in that contribution. Our results provide the first empirical evidence for how the effect of solar radiation on decomposition varies among multiple species. Thus, the effect of solar radiation on the carbon flux between biosphere and atmosphere may depend on the species composition of the vegetation. PMID:26282711

Difference in the crab fauna of mangrove areas at a southwest Florida and a northeast Australia location: Implications for leaf litter processing

USGS Publications Warehouse

McIvor, C.C.; Smith, T. J.

1995-01-01

Existing paradigms suggest that mangrove leaf litter is processed primarily via the detrital pathway in forests in the Caribbean biogeographic realm whereas herbivorous crabs are relatively more important litter processors in the Indo-West Pacific. To test this hypothesis, we used pitfall traps to collect intertidal crabs to characterize the crab fauna in a mangrove estuary in southwest Florida. We also tethered mangrove leaves to determine if herbivorous crabs are major leaf consumers there. We compared the results with previously published data collected in an analogous manner from forests in northeastern Australia. The crab fauna in Rookery Bay, Florida, is dominated by carnivorous xanthid and deposit-feeding ocypodid crabs whereas that of the Murray River in northeastern Australia is dominated by herbivorous grapsid crabs. No leaves tethered at five sites in the forests in Southwest Florida were taken by crabs. This contrasts greatly with reported values of leaf removal by crabs in Australian forests of 28-79% of the leaves reaching the forest floor. These differences in the faunal assemblages and in the fate of marked or tethered leaves provide preliminary support for the hypothesis that leaf litter is in fact processed in fundamentally different ways in the two biogeographic realms.

The Trophic Significance of Bacteria in a Detritus-Based Stream Food Web

Treesearch

Robert O. Hall; Judy L. Meyer

1998-01-01

We compared relative use of streamwater dissolved organic carbon (DOC) by bacteria and the trophic significance of bacteria to invertebrates in two headwater streams at Coweeta Hydrologic Laboratory in North Carolina: a stream with all leaf litter inputs excluded for 1 yr, and a reference stream. Leaf litter standing crop in the treatment stream was

Leaf-litter inputs from an invasive nitrogen-fixing tree influence organic-matter dynamics and nitrogen inputs in a Hawaiian river

Treesearch

Richard A. MacKenzie; Tracy N. Wiegner; Frances Kinslow; Nicole Cormier; Ayron M. Strauch

2013-01-01

Abstract. We examined how invasion of tropical riparian forests by an exotic N-fixing tree (Falcataria moluccana) affects organic-matter dynamics in a Hawaiian river by comparing early stages of leaf-litter breakdown between the exotic F. moluccana and native Metrosideros polymorpha trees. We examined early...

The trophic role of a forest salamander: impacts on invertebrates, leaf litter retention, and the humification process

Treesearch

M. L. Best; H. H. Welsh

2014-01-01

Woodland (Plethodontid) salamanders are the most abundant vertebrates in North American forests, functioning as predators on invertebrates and prey for higher trophic levels. We investigated the role of Ensatina (Ensatina eschscholtzii) in regulating invertebrate numbers and leaf litter retention in a northern California forest. Our objective was...

Quality of soluble organic C, N, and P produced by different types and species of litter: root litter versus leaf litter

USDA-ARS?s Scientific Manuscript database

In forested ecosystems, the quality of dissolved organic matter (DOM) produced by freshly senesced litter may differ by litter type and species, and these differences may influence the amount of DOM that is respired versus that which may either contribute to soil organic matter accumulation or be le...

Using a rainforest-flame forest mosaic to test the hypothesis that leaf and litter fuel flammability is under natural selection.

PubMed

Clarke, Peter J; Prior, Lynda D; French, Ben J; Vincent, Ben; Knox, Kirsten J E; Bowman, David M J S

2014-12-01

We used a mosaic of infrequently burnt temperate rainforest and adjacent, frequently burnt eucalypt forests in temperate eastern Australia to test whether: (1) there were differences in flammability of fresh and dried foliage amongst congeners from contrasting habitats, (2) habitat flammability was related to regeneration strategy, (3) litter fuels were more flammable in frequently burnt forests, (4) the severity of a recent fire influenced the flammability of litter (as this would suggest fire feedbacks), and (5) microclimate contributed to differences in fire hazard amongst habitats. Leaf-level comparisons were made among 11 congeneric pairs from rainforest and eucalypt forests. Leaf-level ignitability, combustibility and sustainability were not consistently higher for taxa from frequently burnt eucalypt forests, nor were they higher for species with fire-driven recruitment. The bulk density of litter-bed fuels strongly influenced flammability, but eucalypt forest litter was not less dense than rainforest litter. Ignitability, combustibility and flame sustainability of community surface fuels (litter) were compared using fuel arrays with standardized fuel mass and moisture content. Forests previously burned at high fire severity did not have consistently higher litter flammability than those burned at lower severity or long unburned. Thus, contrary to the Mutch hypothesis, there was no evidence of higher flammability of litter fuels or leaves from frequently burnt eucalypt forests compared with infrequently burnt rainforests. We suggest the manifest pyrogenicity of eucalypt forests is not due to natural selection for more flammable foliage, but better explained by differences in crown openness and associated microclimatic differences.

Influence of Different Forest System Management Practices on Leaf Litter Decomposition Rates, Nutrient Dynamics and the Activity of Ligninolytic Enzymes: A Case Study from Central European Forests

PubMed Central

Schulz, Elke; Schloter, Michael; Buscot, François; Hofrichter, Martin; Krüger, Dirk

2014-01-01

Leaf litter decomposition is the key ecological process that determines the sustainability of managed forest ecosystems, however very few studies hitherto have investigated this process with respect to silvicultural management practices. The aims of the present study were to investigate the effects of forest management practices on leaf litter decomposition rates, nutrient dynamics (C, N, Mg, K, Ca, P) and the activity of ligninolytic enzymes. We approached these questions using a 473 day long litterbag experiment. We found that age-class beech and spruce forests (high forest management intensity) had significantly higher decomposition rates and nutrient release (most nutrients) than unmanaged deciduous forest reserves (P<0.05). The site with near-to-nature forest management (low forest management intensity) exhibited no significant differences in litter decomposition rate, C release, lignin decomposition, and C/N, lignin/N and ligninolytic enzyme patterns compared to the unmanaged deciduous forest reserves, but most nutrient dynamics examined in this study were significantly faster under such near-to-nature forest management practices. Analyzing the activities of ligninolytic enzymes provided evidence that different forest system management practices affect litter decomposition by changing microbial enzyme activities, at least over the investigated time frame of 473 days (laccase, P<0.0001; manganese peroxidase (MnP), P = 0.0260). Our results also indicate that lignin decomposition is the rate limiting step in leaf litter decomposition and that MnP is one of the key oxidative enzymes of litter degradation. We demonstrate here that forest system management practices can significantly affect important ecological processes and services such as decomposition and nutrient cycling. PMID:24699676

Influence of different forest system management practices on leaf litter decomposition rates, nutrient dynamics and the activity of ligninolytic enzymes: a case study from central European forests.

PubMed

Purahong, Witoon; Kapturska, Danuta; Pecyna, Marek J; Schulz, Elke; Schloter, Michael; Buscot, François; Hofrichter, Martin; Krüger, Dirk

2014-01-01

Leaf litter decomposition is the key ecological process that determines the sustainability of managed forest ecosystems, however very few studies hitherto have investigated this process with respect to silvicultural management practices. The aims of the present study were to investigate the effects of forest management practices on leaf litter decomposition rates, nutrient dynamics (C, N, Mg, K, Ca, P) and the activity of ligninolytic enzymes. We approached these questions using a 473 day long litterbag experiment. We found that age-class beech and spruce forests (high forest management intensity) had significantly higher decomposition rates and nutrient release (most nutrients) than unmanaged deciduous forest reserves (P<0.05). The site with near-to-nature forest management (low forest management intensity) exhibited no significant differences in litter decomposition rate, C release, lignin decomposition, and C/N, lignin/N and ligninolytic enzyme patterns compared to the unmanaged deciduous forest reserves, but most nutrient dynamics examined in this study were significantly faster under such near-to-nature forest management practices. Analyzing the activities of ligninolytic enzymes provided evidence that different forest system management practices affect litter decomposition by changing microbial enzyme activities, at least over the investigated time frame of 473 days (laccase, P<0.0001; manganese peroxidase (MnP), P = 0.0260). Our results also indicate that lignin decomposition is the rate limiting step in leaf litter decomposition and that MnP is one of the key oxidative enzymes of litter degradation. We demonstrate here that forest system management practices can significantly affect important ecological processes and services such as decomposition and nutrient cycling.

Yeast and Macroinvertebrate Communities Associated with Leaf Litter Decomposition in a Second Order Stream

NASA Astrophysics Data System (ADS)

Sampaio, Ana; Cortes, Rui; Leão, Cecília

2004-11-01

The composition of yeast and macroinvertebrate communities was studied on black alder, blue gum eucalyptus and English oak leaves decaying in a stream during a six-month period. ANOVA analysis showed significantly different values (p < 0.0001) of yeast and macroinvertebrate densities among the three leaf litters. Some yeast species such as Cryptococcus albidus (Saito), C. laurentii (Kufferath), Rhodothorula glutinis (Fresenius), R. colostri (Castelli), and Debaryomyces hansenii (Lodder and Kreger-van Rij) were present in all litter types. Other yeasts were restricted to a specific type of litter. Macroinvertebrates were dominated by collectors-gatherers on oak and eucalyptus leaves. Shredders reached highest densities in alder leaves. (

Metal(loid) allocation and nutrient retranslocation in Pinus halepensis trees growing on semiarid mine tailings.

PubMed

Parraga-Aguado, Isabel; Querejeta, Jose-Ignacio; González-Alcaraz, María Nazaret; Conesa, Hector M

2014-07-01

The goal of this study was to evaluate internal metal(loid) cycling and the risk of metal(loid) accumulation in litter from Pinus halepensis trees growing at a mine tailing disposal site in semiarid Southeast Spain. Internal nutrient retranslocation was also evaluated in order to gain insight into the ability of pine trees to cope with the low-fertility soil conditions at the tailings. We measured metal(loid) concentrations in the foliage (young and old needles), woody stems and fresh leaf litter of pine trees growing on tailings. The nutrient status and stable isotope composition of pine foliage (δ(13)C, δ(15)N, δ(18)O as indicators of photosynthesis and water use efficiency) were also analyzed. Tailing soil properties in vegetation patches and in adjacent bare soil patches were characterized as well. Significant amounts of metal(loid)s such us Cd, Cu, Pb and Sb were immobilized in the woody stems of Pinus halepensis trees growing on tailings. Leaf litterfall showed high concentrations of As, Cd, Sb, Pb and Zn, which thereby return to the soil. However, water extractable metal(loid) concentrations in tailing soils were similar between vegetation patches (mineral soil under the litter layer) and bare soil patches. The pines growing on mine tailings showed very low foliar P concentrations in all leaf age classes, which suggests severe P deficiency. Young (current year) needles showed lower accumulation of metal(loid)s, higher nutrient concentrations (P and K), and higher water use efficiency (as indicated by and δ(13)C and δ(18)O data) than older needles. Substantial nutrient resorption occurred before leaf litterfall, with 46% retranslocation efficiency for P and 89% for K. In conclusion, phytostabilization of semiarid mine tailings with Pinus halepensis is feasible but would require careful monitoring of the trace elements released from litterfall, in order to assess the long term risk of metal(loid) transfer to the food chain. Copyright © 2014 Elsevier B.V. All rights reserved.

Comparative water fluxes through leaf litter of tropical plantation trees and the invasive grass Saccharum spontaneum in the Republic of Panama

NASA Astrophysics Data System (ADS)

Park, Andrew; Friesen, Patrick; Serrud, Aneth Aracelly Sarmiento

2010-03-01

SummaryThe hydrological properties of leaf litter layers remain relatively unexplored, especially in tropical vegetation communities. In this paper we explore the hydrological dynamics of litter samples from reforestation plots of tropical hardwoods and the invasive sugar cane Saccharum spontaneum, which these trees were planted to replace. Water holding capacity (WHC) and drying rates were compared under controlled conditions, and throughfall interception, drainage and calculated evaporation were measured in two field experiments (A and B) conducted with different sets of samples. The WHC of samples varied from 3.4 to 6.5 mm in experiment A, and from 1.6 to 7.1 mm in experiment B. Drainage through the litter samples averaged 78.3 ± 34.4% and 61.2 ± 34.70% TF in experiments A and B, respectively. Daily water storage was 70.8 ± 14.25% of total WHC in experiment A and 78.6 ± 25.35% of total WHC in experiment B. Estimated evaporation averaged 34.8 ± 12.52% of WHC in experiment A and 34.3 ± 14.91% of WHC in experiment B. Although significant interspecific differences in WHC, interception of TF and evaporation were recorded, species rankings tended to be different in experiments A and B. The exception was litter from the leguminous tree Gliricidia sepium, which maintained the lowest WHC and water storage in the field in both experiments, but which evaporated water more rapidly than other species. The depth of throughfall draining through litter samples in the field was similar among all species in both experiments. Comparisons of regression slopes also showed that drainage depth increased with increasing throughfall at similar rates among species. On the other hand, both slopes and slope elevations differed among species when drainage was expressed in l kg -1. Patterns of water storage and drainage in our samples were in broad agreement with those of other studies, although WHC and litter necromass in our young tree plantations fell into the lower end of the range reported for mature Amazonian forest.

Fungal role in the movement, leaching and deposition of minerals across leaf litter and soil

NASA Astrophysics Data System (ADS)

Pinzari, Flavia; Maggi, Oriana; Persiani, Anna Maria

2015-04-01

A considerable number of fungi have been described as having the power to translocate nutrients, but little is known about this role in the leaf litter-soil interface food web. A technique for evaluating the mechanisms of cellulose colonization by fungi and the changes in elemental composition of cellulose during its exploitation was set up. Ten sheets of pure cellulose (cotton linter) filter paper (10cm2) were layered to form a pad which was then inserted into a square-shaped terylene netting bag (15cm2), with a mesh size of 1mm2 . This package was then incubated for 6 months under leaf litter originating from an area of a low mixed Mediterranean maquis located in southern Italy (408570N; 138550E). Four different sites as field replicates were considered along three sampling times. The analysis of cellulose sheets by means of Scanning electron microscopy and EDS (Energy Dispersive X-ray spectroscopy) after 45, 180 and 600 days of field incubation has provided evidence of a progressive increase in the fragmentation of the niche represented by the cellulose itself in the course of proceeding of the decomposition. A clear change occurred in the content of trace elements during decomposition: two groups of elements were observed that seemed to have behaved differently over time. A larger group whose average concentration has been increasing with field incubation time was composed by Si, Fe, Al K, Cl, Mg. A second group of three elements (Ca, P and S) instead has followed a very different trend, increasing in some cases significantly and almost logarithmically between the first and the second sampling, and then remaining constant or even decreased (as in the case of Ca) between the second and the third sampling. The first group of microelements is clearly linked to the contribution of the soil (sandy), while the elements of the second group appeared correlated to biological activity. During the decomposition of cellulose Ca enters into fungal enzymatic mechanisms related to the tricarboxylic acid cycle (i.e. accumulation or precipitation of calcium oxalate in the environment); this can explain the peculiar behaviour of this element across the incubation time. The P and S are biogenic elements that enter directly in the composition of proteins and nucleic acids and other fundamental biological molecules (ATP , co-enzymes, structural proteins), and could be associated to the extent of fungal colonisation of cellulosic material. The results of the study provided evidence of a functional role of fungal hyphae and rhizomorphs in the movement, leaching and deposition of minerals across soil and leaf litter layers. (417 words)

Beech cupules as keystone structures for soil fauna.

PubMed

Melguizo-Ruiz, Nereida; Jiménez-Navarro, Gerardo; Moya-Laraño, Jordi

2016-01-01

Facilitative or positive interactions are ubiquitous in nature and play a fundamental role in the configuration of ecological communities. In particular, habitat modification and niche construction, in which one organism locally modifies abiotic conditions and favours other organisms by buffering the effects of adverse environmental factors, are among the most relevant facilitative interactions. In line with this, 'keystone structures', which provide resources, refuge, or advantageous services decisive for other species, may allow the coexistence of various species and thus considerably contribute to diversity maintenance. Beech cupules are woody husks harbouring beech fruits that remain in the forest soil for relatively long periods of time. In this study, we explored the potential role of these cupules in the distribution and maintenance of the soil fauna inhabiting the leaf litter layer. We experimentally manipulated cupule availability and soil moisture in the field to determine if such structures are limiting and can provide moist shelter to soil animals during drought periods, contributing to minimize desiccation risks. We measured invertebrate abundances inside relative to outside the cupules, total abundances in the leaf litter and animal body sizes, in both dry and wet experimental plots. We found that these structures are preferentially used by the most abundant groups of smaller soil animals-springtails, mites and enchytraeids-during droughts. Moreover, beech cupules can be limiting, as an increase in use was found with higher cupule densities, and are important resources for many small soil invertebrates, driving the spatial structure of the soil community and promoting higher densities in the leaf litter, probably through an increase in habitat heterogeneity. We propose that fruit woody structures should be considered 'keystone structures' that contribute to soil community maintenance. Therefore, beech trees may indirectly facilitate soil fauna activities through their decaying fruit husks, hence acting as ecosystem engineers.

Soil respiration and aboveground litter dynamics of a tropical transitional forest in northwest Mato Grosso, Brazil

NASA Astrophysics Data System (ADS)

Valentini, Carla Maria Abido; Sanches, Luciana; de Paula, SéRgio Roberto; Vourlitis, George Louis; de Souza Nogueira, José; Pinto, Osvaldo Borges; de Almeida Lobo, Francisco

2008-03-01

Measurements of soil CO2 efflux, litter production, and the surface litter pool biomass were made over a 1 year period in a tropical transitional forest near Sinop, Mato Grosso, Brazil with the aim of quantifying the seasonal variation in soil respiration and litter decomposition and the annual contribution of litter decomposition to soil CO2 efflux. Average annual soil CO2 efflux (±95% confidence interval (CI)) was 7.91 ± 1.16 g C m-2 d-1. Soil CO2 efflux was highest during the November-February wet season (9.15 ± 0.90 g C m-2 d-1) and lowest during the May-September dry season (6.19 ± 1.40 g C m-2 d-1), and over 60% of the variation in seasonal soil CO2 efflux was explained by seasonal variations in soil temperature and moisture. Mass balance estimates of mean (±95% CI) decomposition rates were statistically different between the wet and dry seasons (0.66 ± 0.08 and 1.65 ± 0.10 g C m-2 d-1, respectively), and overall, decomposition of leaf litter comprised 16% of the average annual soil respiration. Leaf litter production was higher during the dry season, and mean (±95% CI) leaf litter fall (5.6 ± 1.7 Mg ha-1) comprised 73% of the total litter fall (7.8 ± 2.3 Mg ha-1). Average (±95% CI) annual litter pool biomass was estimated to be 5.5 ± 0.3 Mg ha-1, which was similar to the measured pool size (5.7 ± 2.2 Mg ha-1). Overall, seasonal variations in environmental variables, specifically water availability (soil moisture and rainfall), had a profound influence on litter production, soil respiration, and surface litter decomposition.

Effects of soil compaction, forest leaf litter and nitrogen fertilizer on two oak species and microbial activity

Treesearch

D. Jordan; F., Jr. Ponder; V. C. Hubbard

2003-01-01

A greenhouse study examined the effects of soil compaction and forest leaf litter on the growth and nitrogen (N) uptake and recovery of red oak (Quercus rubra L.) and scarlet oak (Quercus coccinea Muencch) seedlings and selected microbial activity over a 6-month period. The experiment had a randomized complete block design with...

Rates of in situ carbon mineralization in relation to land-use, microbial community and edaphic characteristics

Treesearch

M.S. Strickland; M.A. Callaham; C.A. Davies; C.L. Lauber; K. Ramirez; D.D. Richter; N. Fierer; M.A. Bradford

2010-01-01

Plant-derived carbon compounds enter soils in a number of forms; two of the most abundant being leaf litter and rhizodeposition. Our knowledge concerning the predominant controls on the cycling of leaf litter far outweighs that for rhizodeposition even though the constituents of rhizodeposits includes a cocktail of low molecular weight organic compounds which represent...

Food Web Structure and Basal Resource Utilization along a Tropical Island Stream Continuum, Puerto Rico.

Treesearch

James G. March; Catherine M. Pringle

2003-01-01

Tropical stream food webs are thought to be based primarily on terrestrial resources (leaf litter) in small forested headwater streams and algal resources in larger, wider streams. In tropical island streams, the dominant consumers are often omnivorous freshwater shrimps that consume algae, leaf litter, insects, and other shrimps. We used stable isotope analysis...

Impacts of emerald ash borer-induced tree mortality on leaf litter arthropods and exotic earthworms

Treesearch

Michael D. Ulyshen; Wendy S. Klooster; William T. Barrington; Daniel A. Herns

2011-01-01

Because leaf litter occurs at the interface between the soil and atmosphere, the invertebrates inhabiting it represent important linkages between above- and below-ground food webs. The responses of these organisms to forest disturbance brought about by invasive species should therefore have far-reaching ecological effects. The purpose of this study was to explore how...

Nutritional benefit from leaf litter utilization in the pitcher plant Nepenthes ampullaria.

PubMed

Pavlovič, Andrej; Slováková, Ludmila; Šantrůček, Jiří

2011-11-01

The pitcher plant Nepenthes ampullaria has an unusual growth pattern, which differs markedly from other species in the carnivorous genus Nepenthes. Its pitchers have a reflexed lid and sit above the soil surface in a tighly packed 'carpet'. They contain a significant amount of plant-derived materials, suggesting that this species is partially herbivorous. We tested the hypothesis that the plant benefits from leaf litter utilization by increased photosynthetic efficiency sensu stricto cost/benefit model. Stable nitrogen isotope abundance indicated that N. ampullaria derived around 41.7 ± 5.5% of lamina and 54.8 ± 7.0% of pitcher nitrogen from leaf litter. The concentrations of nitrogen and assimilation pigments, and the rate of net photosynthesis (A(N)), increased in the lamina as a result of feeding, but did not increase in the trap. However, maximal (F(v) /F(m)) and effective photochemical quantum yield of photosystem II (Φ(PSII)) were unaffected. Our data indicate that N. ampullaria benefits from leaf litter utilization and our study provides the first experimental evidence that the unique nitrogen sequestration strategy of N. ampullaria provides benefits in term of photosynthesis and growth. © 2011 Blackwell Publishing Ltd.

Ligninolytic Activity at 0 °C of Fungi on Oak Leaves Under Snow Cover in a Mixed Forest in Japan.

PubMed

Miyamoto, Toshizumi; Koda, Keiichi; Kawaguchi, Arata; Uraki, Yasumitsu

2017-08-01

Despite the importance of litter decomposition under snow cover in boreal forests and tundra, very little is known regarding the characteristics and functions of litter-decomposing fungi adapted to the cold climate. We investigated the decomposition of oak leaves in a heavy snowfall forest region of Japan. The rate of litter weight loss reached 26.5% during the snow cover period for 7 months and accounted for 64.6% of the annual loss (41.1%). Although no statistically significant lignin loss was detected, decolourization portions of oak leaf litter, which was attributable to the activities of ligninolytic fungi, were observed during snow cover period. This suggests that fungi involved in litter decomposition can produce extracellular enzymes to degrade lignin that remain active at 0 °C. Fungi were isolated from oak leaves collected from the forest floor under the snow layer. One hundred and sixty-six strains were isolated and classified into 33 operational taxonomic units (OTUs) based on culture characteristics and nuclear rDNA internal transcribed spacer (ITS) region sequences. To test the ability to degrade lignin, the production of extracellular phenoloxidases by isolates was quantified at 0 °C. Ten OTUs (9 Ascomycota and 1 Basidiomycota) of fungi exhibited mycelial growth and ligninolytic activity. These results suggested that some litter-decomposing fungi that had the potential to degrade lignin at 0 °C significantly contribute to litter decomposition under snow cover.

ForCent model development and testing using the Enriched Background Isotope Study experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parton, W.J.; Hanson, P. J.; Swanston, C.

The ForCent forest ecosystem model was developed by making major revisions to the DayCent model including: (1) adding a humus organic pool, (2) incorporating a detailed root growth model, and (3) including plant phenological growth patterns. Observed plant production and soil respiration data from 1993 to 2000 were used to demonstrate that the ForCent model could accurately simulate ecosystem carbon dynamics for the Oak Ridge National Laboratory deciduous forest. A comparison of ForCent versus observed soil pool {sup 14}C signature ({Delta} {sup 14}C) data from the Enriched Background Isotope Study {sup 14}C experiment (1999-2006) shows that the model correctly simulatesmore » the temporal dynamics of the {sup 14}C label as it moved from the surface litter and roots into the mineral soil organic matter pools. ForCent model validation was performed by comparing the observed Enriched Background Isotope Study experimental data with simulated live and dead root biomass {Delta} {sup 14}C data, and with soil respiration {Delta} {sup 14}C (mineral soil, humus layer, leaf litter layer, and total soil respiration) data. Results show that the model correctly simulates the impact of the Enriched Background Isotope Study {sup 14}C experimental treatments on soil respiration {Delta} {sup 14}C values for the different soil organic matter pools. Model results suggest that a two-pool root growth model correctly represents root carbon dynamics and inputs to the soil. The model fitting process and sensitivity analysis exposed uncertainty in our estimates of the fraction of mineral soil in the slow and passive pools, dissolved organic carbon flux out of the litter layer into the mineral soil, and mixing of the humus layer into the mineral soil layer.« less

ForCent Model Development and Testing using the Enriched Background Isotope Study (EBIS) Experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parton, William; Hanson, Paul J; Swanston, Chris

The ForCent forest ecosystem model was developed by making major revisions to the DayCent model including: (1) adding a humus organic pool, (2) incorporating a detailed root growth model, and (3) including plant phenological growth patterns. Observed plant production and soil respiration data from 1993 to 2000 were used to demonstrate that the ForCent model could accurately simulate ecosystem carbon dynamics for the Oak Ridge National Laboratory deciduous forest. A comparison of ForCent versus observed soil pool 14C signature (? 14C) data from the Enriched Background Isotope Study 14C experiment (1999-2006) shows that the model correctly simulates the temporal dynamicsmore » of the 14C label as it moved from the surface litter and roots into the mineral soil organic matter pools. ForCent model validation was performed by comparing the observed Enriched Background Isotope Study experimental data with simulated live and dead root biomass ? 14C data, and with soil respiration ? 14C (mineral soil, humus layer, leaf litter layer, and total soil respiration) data. Results show that the model correctly simulates the impact of the Enriched Background Isotope Study 14C experimental treatments on soil respiration ? 14C values for the different soil organic matter pools. Model results suggest that a two-pool root growth model correctly represents root carbon dynamics and inputs to the soil. The model fitting process and sensitivity analysis exposed uncertainty in our estimates of the fraction of mineral soil in the slow and passive pools, dissolved organic carbon flux out of the litter layer into the mineral soil, and mixing of the humus layer into the mineral soil layer.« less

Effects of elevated concentrations of atmospheric CO2 and tropospheric O3 on leaf litter production and chemistry in trembling aspen and paper birch communities

Treesearch

Lingli Liu; John S. King; Christian P. Giardina

2005-01-01

Human activities are increasing the concentrations of atmospheric carbon dioxide ([CO2]) and tropospheric ozone ([O3]), potentially leading to changes in the quantity and chemical quality of leaf litter inputs to forest soils. Because the quality and quantity of labile and recalcitrant carbon (C) compounds influence forest...

Drought and detritivores determine leaf litter decomposition in calcareous streams of the Ebro catchment (Spain).

PubMed

Monroy, Silvia; Menéndez, Margarita; Basaguren, Ana; Pérez, Javier; Elosegi, Arturo; Pozo, Jesús

2016-12-15

Drought, an important environmental factor affecting the functioning of stream ecosystems, is likely to become more prevalent in the Mediterranean region as a consequence of climate change and enhanced water demand. Drought can have profound impacts on leaf litter decomposition, a key ecosystem process in headwater streams, but there is still limited information on its effects at the regional scale. We measured leaf litter decomposition across a gradient of aridity in the Ebro River basin. We deployed coarse- and fine-mesh bags with alder and oak leaves in 11 Mediterranean calcareous streams spanning a range of over 400km, and determined changes in discharge, water quality, leaf-associated macroinvertebrates, leaf quality and decomposition rates. The study streams were subject to different degrees of drought, specific discharge (Ls -1 km -2 ) ranging from 0.62 to 9.99. One of the streams dried out during the experiment, another one reached residual flow, whereas the rest registered uninterrupted flow but with different degrees of flow variability. Decomposition rates differed among sites, being lowest in the 2 most water-stressed sites, but showed no general correlation with specific discharge. Microbial decomposition rates were not correlated with final nutrient content of litter nor to fungal biomass. Total decomposition rate of alder was positively correlated to the density and biomass of shredders; that of oak was not. Shredder density in alder bags showed a positive relationship with specific discharge during the decomposition experiment. Overall, the results point to a complex pattern of litter decomposition at the regional scale, as drought affects decomposition directly by emersion of bags and indirectly by affecting the functional composition and density of detritivores. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Differences in the sensitivity of fungi and bacteria to season and invertebrates affect leaf litter decomposition in a Mediterranean stream.

PubMed

Mora-Gómez, Juanita; Elosegi, Arturo; Duarte, Sofia; Cássio, Fernanda; Pascoal, Cláudia; Romaní, Anna M

2016-08-01

Microorganisms are key drivers of leaf litter decomposition; however, the mechanisms underlying the dynamics of different microbial groups are poorly understood. We investigated the effects of seasonal variation and invertebrates on fungal and bacterial dynamics, and on leaf litter decomposition. We followed the decomposition of Populus nigra litter in a Mediterranean stream through an annual cycle, using fine and coarse mesh bags. Irrespective of the season, microbial decomposition followed two stages. Initially, bacterial contribution to total microbial biomass was higher compared to later stages, and it was related to disaccharide and lignin degradation; in a later stage, bacteria were less important and were associated with hemicellulose and cellulose degradation, while fungi were related to lignin decomposition. The relevance of microbial groups in decomposition differed among seasons: fungi were more important in spring, whereas in summer, water quality changes seemed to favour bacteria and slowed down lignin and hemicellulose degradation. Invertebrates influenced litter-associated microbial assemblages (especially bacteria), stimulated enzyme efficiencies and reduced fungal biomass. We conclude that bacterial and fungal assemblages play distinctive roles in microbial decomposition and differ in their sensitivity to environmental changes, ultimately affecting litter decomposition, which might be particularly relevant in highly seasonal ecosystems, such as intermittent streams. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Litter dynamics in two Sierran mixed conifer forests. I. Litterfall and decomposition rates

USGS Publications Warehouse

Stohlgren, Thomas J.

1988-01-01

Litterfall was measured for 4 years and leaf litter decomposition rates were studied for 3.6 years in two mixed conifer forest (giant sequoia-fir and fir-pine) in the southern Sierra Nevada of California. The giant sequoia-fir forest (GS site) was dominated by giant sequoia (Sequoiadendron giganteum (Lindl.) Buchh.), white fir (Abies concolor Lindl. & Gord.), and sugar pine (Pinus lambertiana Dougl.). The fir-pine forest (FP site) was dominated by white fir, sugar pine, and incense cedar (Calocedrus decurrens (Torr.) Florin). Litterfall, including large woody debris -1•year-1 compared with 4355 kg•ha-1•year-1 at the FP site (3.4:1). In the GS site, leaf litter decomposition after 3.6 years was slowest for giant sequoia (28.2% mass loss), followed by sugar pine (34.3%) and white fie (45.1%). In the FP site, mass loss was slowest for sugar pine (40.0%), followed by white fir (45.1%), while incense cedar showed the greatest mass loss (56.9%) after 3.6 years. High litterfall rates of large woody debris (i.e., 2.5-15.2 cm diameter) and slow rates of leaf litter decomposition in the giant sequoia-fir forest type may result in higher litter accumulation rates than in the fir-pine type. Leaf litter times to 95% decay for the GS and FP sites were 30 and 27 years, respectively, if the initial 0.7-year period (a short period of rapid mass decay) was ignored in the calculation. A mass balance approach for total litterfall (<15.2 cm diameter) decomposition yielded lower decay constants than did the litterbag study and therefore longer times to 95% decay (57 years for the GS site and 62 years for the FP site).

Does leaf chemistry differentially affect breakdown in tropical versus temperate streams? Importance of standardized analytical techniques to measure leaf chemistry

Treesearch

Marcelo Ardon; Catherine M. Pringle; Susan L. Eggert

2009-01-01

Comparisons of the effects of leaf litter chemistry on leaf breakdown rates in tropical vs temperate streams are hindered by incompatibility among studies and across sites of analytical methods used to...

C, N and P fertilization in an Amazonian rainforest supports stoichiometric dissimilarity as a driver of litter diversity effects on decomposition

PubMed Central

Barantal, Sandra; Schimann, Heidy; Fromin, Nathalie; Hättenschwiler, Stephan

2014-01-01

Plant leaf litter generally decomposes faster as a group of different species than when individual species decompose alone, but underlying mechanisms of these diversity effects remain poorly understood. Because resource C : N : P stoichiometry (i.e. the ratios of these key elements) exhibits strong control on consumers, we supposed that stoichiometric dissimilarity of litter mixtures (i.e. the divergence in C : N : P ratios among species) improves resource complementarity to decomposers leading to faster mixture decomposition. We tested this hypothesis with: (i) a wide range of leaf litter mixtures of neotropical tree species varying in C : N : P dissimilarity, and (ii) a nutrient addition experiment (C, N and P) to create stoichiometric similarity. Litter mixtures decomposed in the field using two different types of litterbags allowing or preventing access to soil fauna. Litter mixture mass loss was higher than expected from species decomposing singly, especially in presence of soil fauna. With fauna, synergistic litter mixture effects increased with increasing stoichiometric dissimilarity of litter mixtures and this positive relationship disappeared with fertilizer addition. Our results indicate that litter stoichiometric dissimilarity drives mixture effects via the nutritional requirements of soil fauna. Incorporating ecological stoichiometry in biodiversity research allows refinement of the underlying mechanisms of how changing biodiversity affects ecosystem functioning. PMID:25320173

Effects of elevated atmospheric Co2 and tropospheric O3 on nutrient dynamics: decomposition of leaf litter in trembling aspen and paper birch communities. Plant Soil. 299:65–82.

Treesearch

Lingli Liu; John S. King; Christian P. Giardina

2007-01-01

Atmospheric changes could strongly influence how terrestrial ecosystems function by altering nutrient cycling. We examined how the dynamics of nutrient release from leaf litter responded to two important atmospheric changes: rising atmospheric Co2 and tropospheric O3. We evaluated the independent and combined effects of...

The Distribution and Abundance of Leaf Litter Arthropods in MOFEP Sites 1, 2, and 3

Treesearch

Jan Weaver; Sarah Heyman

1997-01-01

In June 1993, we collected 144 leaf litter samples from 36 plots (4 samples/plot) located in MOFEP forest sites 1, 2 and 3. Half of the plots were placed randomly on northeast-facing stands (ELT 18), and half randomly placed on southwest-facing stands (ELT 17). Arthropods were extracted using Tullgren funnels, and then sorted into morpho-species, counted, and measured...

Biodiversity and ecosystem function in species-poor communities: community structure and leaf litter breakdown in a Pacific island stream

Treesearch

Jonathan P. Benstead; James G. March; Catherine M. Pringle; Katherine C. Ewel; John W. Short

2009-01-01

Pacific island stream communities are species-poor because of the effects of extreme geographic isolation on colonization rates of taxa common to continental regions. The effects of such low species richness on stream ecosystem function are not well understood. Here, we provide data on community structure and leaf litter breakdown rate in a virtually pristine stream on...

The Impact of Coffee and Pasture Agriculture on Predatory and Omnivorous Leaf-Litter Ants

PubMed Central

Dias, Nivia da Silva; Zanetti, Ronald; Santos, Mônica Silva; Peñaflor, Maria Fernanda Gomes Villalba; Broglio, Sônia Maria Forti; Delabie, Jacques Hubert Charles

2013-01-01

Ants are known to function as reliable biological indicators for habitat impact assessment. They play a wide range of ecological roles depending on their feeding and nesting habits. By clustering ants in guilds, it is possible both to assess how agriculture and forest fragmentation can disturb ant communities and to predict the ecological impacts due to losses of a specific guild. This study aimed at determining the impact of non-shaded coffee and pasture agriculture on predatory and omnivorous guilds of leaf-litter ants of Atlantic Forest fragments in Minas Gerais, Brazil. Both coffee and pasture agriculture influenced leaf-litter ant community, although coffee was more disruptive than pasture. Coffee agriculture not only disturbed the diversity of predatory ants, but also negatively affected the number of predatory and omnivorous ants when compared to forest fragments. In contrast, pasture agriculture only disrupted the abundance of predatory ants. Fragment edges skirting crops were negatively affected in terms of leaf-litter ant abundance, but not diversity. Cluster analysis showed that forest fragments were similar irrespective of the cultivation, but the borders were similar to the crop. The study assessed agriculture impact by surveying ant guilds, and revealed that the predatory guild is more susceptible than omnivorous ants. PMID:23902334

The impact of coffee and pasture agriculture on predatory and omnivorous leaf-litter ants.

PubMed

Dias, Nivia da Silva; Zanetti, Ronald; Santos, Mônica Silva; Peñaflor, Maria Fernanda Gomes Villalba; Broglio, Sônia Maria Forti; Delabie, Jacques Hubert Charles

2013-01-01

Ants are known to function as reliable biological indicators for habitat impact assessment. They play a wide range of ecological roles depending on their feeding and nesting habits. By clustering ants in guilds, it is possible both to assess how agriculture and forest fragmentation can disturb ant communities and to predict the ecological impacts due to losses of a specific guild. This study aimed at determining the impact of non-shaded coffee and pasture agriculture on predatory and omnivorous guilds of leaf-litter ants of Atlantic Forest fragments in Minas Gerais, Brazil. Both coffee and pasture agriculture influenced leaf-litter ant community, although coffee was more disruptive than pasture. Coffee agriculture not only disturbed the diversity of predatory ants, but also negatively affected the number of predatory and omnivorous ants when compared to forest fragments. In contrast, pasture agriculture only disrupted the abundance of predatory ants. Fragment edges skirting crops were negatively affected in terms of leaf-litter ant abundance, but not diversity. Cluster analysis showed that forest fragments were similar irrespective of the cultivation, but the borders were similar to the crop. The study assessed agriculture impact by surveying ant guilds, and revealed that the predatory guild is more susceptible than omnivorous ants.

Community-specific impacts of exotic earthworm invasions on soil carbon dynamics in a sandy temperate forest.

PubMed

Crumsey, Jasmine M; Le Moine, James M; Capowiez, Yvan; Goodsitt, Mitchell M; Larson, Sandra C; Kling, George W; Nadelhoffer, Knute J

2013-12-01

Exotic earthworm introductions can alter above- and belowground properties of temperate forests, but the net impacts on forest soil carbon (C) dynamics are poorly understood. We used a mesocosm experiment to examine the impacts of earthworm species belonging to three different ecological groups (Lumbricus terrestris [anecic], Aporrectodea trapezoides [endogeic], and Eisenia fetida [epigeic]) on C distributions and storage in reconstructed soil profiles from a sandy temperate forest soil by measuring CO2 and dissolved organic carbon (DOC) losses, litter C incorporation into soil, and soil C storage with monospecific and species combinations as treatments. Soil CO2 loss was 30% greater from the Endogeic x Epigeic treatment than from controls (no earthworms) over the first 45 days; CO2 losses from monospecific treatments did not differ from controls. DOC losses were three orders of magnitude lower than CO2 losses, and were similar across earthworm community treatments. Communities with the anecic species accelerated litter C mass loss by 31-39% with differential mass loss of litter types (Acer rubrum > Populus grandidentata > Fagus grandifolia > Quercus rubra > or = Pinus strobus) indicative of leaf litter preference. Burrow system volume, continuity, and size distribution differed across earthworm treatments but did not affect cumulative CO2 or DOC losses. However, burrow system structure controlled vertical C redistribution by mediating the contributions of leaf litter to A-horizon C and N pools, as indicated by strong correlations between (1) subsurface vertical burrows made by anecic species, and accelerated leaf litter mass losses (with the exception of P. strobus); and (2) dense burrow networks in the A-horizon and the C and N properties of these pools. Final soil C storage was slightly lower in earthworm treatments, indicating that increased leaf litter C inputs into soil were more than offset by losses as CO2 and DOC across earthworm community treatments.

Microbiological and chemical properties of litter from different chicken types and production systems.

PubMed

Omeira, N; Barbour, E K; Nehme, P A; Hamadeh, S K; Zurayk, R; Bashour, I

2006-08-15

Chicken litter is produced in large quantities from all types of poultry raising activities. It is primarily used for land application, thus it is essential to analyze its properties before it is released to the environment. The objective of this study is to compare the microbiological and chemical properties of litter generated from layer and broiler chickens reared under intensive and free-range production systems. The microbiological analysis consisted of the enumeration of total bacteria, total coliforms, Staphylococcus species, Salmonella species and Clostridium perfringens. Chicken litter from layers reared under intensive and free range systems showed lower mean total bacterial count than the litter collected from chicken broilers reared under either of the two systems (P=0.0291). The litter from intensive layers had the lowest mean total coliform counts (P=0.0222) while the lowest Staphylococcus species count was observed in the litter from free-range layers (P=0.0077). The C. perfringens count was the lowest in chicken litter from intensively raised broilers and layers (P=0.0001). The chemical properties of litter from the different chicken types and production systems were compared based on determination of pH, electrical conductivity, carbon, nitrogen, phosphorus, potassium, cadmium and zinc. Litter from free-range broilers showed the highest pH value (P=0.0005); however, the electrical conductivity was higher in the litter from both intensive and free-range layers compared to the litter from both broiler production systems (P=0.0117). Chicken litter from intensive systems had higher nitrogen content than litter from free-range systems (P=0.0000). The total phosphorus was the lowest in free-range broiler litter (P=0.0001), while the total potassium was the lowest in litter from intensively managed broilers (P=0.0000). Zinc appeared higher in litter from layers compared to that from broilers (P=0.0101). The cadmium content was higher in the litter from free-range broilers and layers compared to that in the litter from intensively managed systems (P=0.0439). Staphylococcus species in the litter as well as cadmium concentrations seem to be the most critical parameters presenting risks on the environment and on human health. Based on the lowest coliform counts (an indication of water pollution), the high nutrient levels and the low cadmium values, litter from intensively managed layers appears as the most suitable for application on agricultural soils.

A comparative in situ decomposition study using still born piglets and leaf litter from a deciduous forest.

PubMed

Olakanye, Ayodeji O; Nelson, Andrew; Ralebitso-Senior, T Komang

2017-07-01

A cadaver and dead plant organic matter, or litter, are rich energy sources that undergo a complex decomposition process, which impact the surrounding environmental microbiota. Advances in molecular microbiology techniques, with study of the 16S RNA genes, in particular, have highlighted the application of forensic ecogenomics in addressing key knowledge gaps. To investigate subsurface microbiome shifts as a novel tool to establish "postmortem microbial clock" and augment postmortem interval (PMI) and time-since-burial estimations, an in situ study with triplicate underground burials of piglets as human taphonomic proxies and Quercus robur leaf litter was monitored for 270 days. Changes in microbial community structure and composition were related directly to changes in seasonal temperature, with microbial shifts more pronounced during the summer. For example, Methylococcaceae could be used as seasonal bacterial indicators, from winter to summer, in establishing postmortem microbial clock for this site. Furthermore, Methylophilaceae (Methylophilales order) and Anaerolineaceae would differentiate for the piglet and leaf litter soils, respectively, 180 days after internment. Copyright © 2017 Elsevier B.V. All rights reserved.

High variation in foliage and leaf litter chemistry among 45 tree species of a neotropical rainforest community.

PubMed

Hättenschwiler, Stephan; Aeschlimann, Beat; Coûteaux, Marie-Madeleine; Roy, Jacques; Bonal, Damien

2008-01-01

Distinct ecosystem level carbon : nitrogen : phosphorus (C : N : P) stoichiometries in forest foliage have been suggested to reflect ecosystem-scale selection for physiological strategies in plant nutrient use. Here, this hypothesis was explored in a nutrient-poor lowland rainforest in French Guiana. Variation in C, N and P concentrations was evaluated in leaf litter and foliage from neighbour trees of 45 different species, and the litter concentrations of major C fractions were also measured. Litter C ranged from 45.3 to 52.4%, litter N varied threefold (0.68-2.01%), and litter P varied seven-fold (0.009-0.062%) among species. Compared with foliage, mean litter N and P concentrations decreased by 30% and 65%, respectively. Accordingly, the range in mass-based N : P shifted from 14 to 55 in foliage to 26 to 105 in litter. Resorption proficiencies indicated maximum P withdrawal in most species, but with a substantial increase in variation in litter P compared with foliage. These data suggest that constrained ecosystem-level C : N : P ratios do not preclude the evolution of highly diversified strategies of nutrient use and conservation among tropical rainforest tree species. The resulting large variation in litter quality will influence stoichiometric constraints within the decomposer food web, with potentially far-ranging consequences on nutrient dynamics and plant-soil feedbacks.

Molecular characteristics of continuously released DOM during one year of root and leaf litter decomposition

NASA Astrophysics Data System (ADS)

Altmann, Jens; Jansen, Boris; Kalbitz, Karsten; Filley, Timothy

2013-04-01

Dissolved organic matter (DOM) is one of the most dynamic carbon pools linking the terrestrial with the aquatic carbon cycle. Besides the insecure contribution of terrestrial DOM to the greenhouse effect, DOM also plays an important role for the mobility and availability of heavy metals and organic pollutants in soils. These processes depend very much on the molecular characteristics of the DOM. Surprisingly the processes that determine the molecular composition of DOM are only poorly understood. DOM can originate from various sources, which influence its molecular composition. It has been recognized that DOM formation is not a static process and DOM characteristics vary not only between different carbon sources. However, molecular characteristics of DOM extracts have scarcely been studied continuously over a longer period of time. Due to constant molecular changes of the parent litter material or soil organic matter during microbial degradation, we assumed that also the molecular characteristics of litter derived DOM varies at different stages during root and needle decomposition. For this study we analyzed the chemical composition of root and leaf samples of 6 temperate tree species during one year of litter decomposition in a laboratory incubation. During this long-term experiment we measured continuously carbon and nitrogen contents of the water extracts and the remaining residues, C mineralization rates, and the chemical composition of water extracts and residues by Curie-point pyrolysis mass spectrometry with TMAH We focused on the following questions: (I) How mobile are molecules derived from plant polymers like tannin, lignin, suberin and cutin? (II) How does the composition of root and leaf derived DOM change over time in dependence on the stage of decomposition and species? Litter derived DOM was generally dominated by aromatic compounds. Substituded fatty acids as typically cutin or suberin derived were not detected in the water extracts. Fresh leaf and needle samples released a much higher amount of tannins than fresh root samples. At later litter decomposition stages the influence of tannins decreased and lignin derived phenols dominated the extracts. With ongoing litter degradation the degree of oxidation for the litter material increased, which was also reflected by the water extracted molecules.

SOA Formation Potential of Emissions from Soil and Leaf Litter

NASA Astrophysics Data System (ADS)

Faiola, C. L.; Vanderschelden, G. S.; Wen, M.; Cobos, D. R.; Jobson, B. T.; VanReken, T. M.

2013-12-01

In the United States, emissions of volatile organic compounds (VOCs) from natural sources exceed all anthropogenic sources combined. VOCs participate in oxidative chemistry in the atmosphere and impact the concentrations of ozone and particulate material. The formation of secondary organic aerosol (SOA) is particularly complex and is frequently underestimated using state-of-the-art modeling techniques. We present findings that suggest emissions of important SOA precursors from soil and leaf litter are higher than current inventories would suggest, particularly under conditions typical of Fall and Spring. Soil and leaf litter samples were collected at Big Meadow Creek from the University of Idaho Experimental Forest. The dominant tree species in this area of the forest are ponderosa pine, Douglas-fir, and western larch. Samples were transported to the laboratory and housed within a 0.9 cubic meter Teflon dynamic chamber where VOC emissions were continuously monitored with a GC-FID-MS and PTR-MS. Aerosol was generated from soil and leaf litter emissions by pumping the emissions into a 7 cubic meter Teflon aerosol growth chamber where they were oxidized with ozone in the absence of light. The evolution of particle microphysical and chemical characteristics was monitored over the following eight hours. Particle size distribution and chemical composition were measured with a SMPS and HR-ToF-AMS respectively. Monoterpenes dominated the emission profile with emission rates up to 283 micrograms carbon per meter squared per hour. The dominant monoterpenes emitted were beta-pinene, alpha-pinene, and delta-3-carene in descending order. The composition of the SOA produced was similar to biogenic SOA formed from oxidation of ponderosa pine emissions and alpha-pinene. Measured soil/litter monoterpene emission rates were compared with modeled canopy emissions. Results suggest that during fall and spring when tree emissions are lower, monoterpene emissions within forests may be dominated by soil/litter emissions--soil/litter monoterpene emissions in spring could contribute up to 63% of total forest emissions. If this is the case, a significant portion of total forest monoterpene emission rates would be controlled by factors that affect soil/litter emissions rather than factors that affect plant emissions.

Aboveground biomass, wood volume, nutrient stocks and leaf litter in novel forests compared to native forests and tree plantations in Puerto Rico

Treesearch

A.E. Lugo; O. Abelleira Martínez; J. Fonseca da Silva

2012-01-01

The article presents comparative data for aboveground biomass, wood volume, nutirent stocks (N, P, K) and leaf litter in different types of forests in Puerto Rico. The aim of the study is to assess how novel forests of Castilla elastica, Panama Rubber Tree, and Spathodea campanulata, African Tulip Tree, compare with tree plantations and native historical forests (both...

Leaf litter of invasive Chinese tallow (Triadica sebifera) negatively affects hatching success of an aquatic breeding anuran, the southern leopard frog (Lithobates sphenocephalus)

Treesearch

C.K. Adams; D. Saenz

2012-01-01

Chinese tallow (Triadica sebifera (L.) Small) is an aggressive invasive tree species that can be abundant in parts of its non-native range. This tree species has the capability of producing monocultures, by outcompeting native trees, which can be in or near wetlands that are utilized by breeding amphibians. Existing research suggests that leaf litter from invasive...

Mercury bioaccumulation studies in the National Water-Quality Assessment Program--biological data from New York and South Carolina, 2005-2009

USGS Publications Warehouse

Beaulieu, Karen M.; Button, Daniel T.; Eikenberry, Barbara C. Scudder; Riva-Murray, Karen; Chasar, Lia C.; Bradley, Paul M.; Burns, Douglas A.

2012-01-01

The U.S. Geological Survey National Water-Quality Assessment Program conducted a multidisciplinary study from 2005–09 to investigate the bioaccumulation of mercury in streams from two contrasting environmental settings. Study areas were located in the central Adirondack Mountains region of New York and the Inner Coastal Plain of South Carolina. Fish, macroinvertebrates, periphyton (attached algae and associated material), detritus, and terrestrial leaf litter were collected. Fish were analyzed for total mercury; macroinvertebrates, periphyton, and terrestrial leaf litter were analyzed for total mercury and methylmercury; and select samples of fish, macroinvertebrates, periphyton, detritus, and terrestrial leaf litter were analyzed for stable isotopes of carbon (δ13C) and nitrogen (δ15N). This report presents methodology and data on total mercury, methylmercury, stable isotopes, and other ecologically relevant measurements in biological tissues.

Plant litter functional diversity effects on litter mass loss depend on the macro-detritivore community.

PubMed

Patoine, Guillaume; Thakur, Madhav P; Friese, Julia; Nock, Charles; Hönig, Lydia; Haase, Josephine; Scherer-Lorenzen, Michael; Eisenhauer, Nico

2017-11-01

A better understanding of the mechanisms driving litter diversity effects on decomposition is needed to predict how biodiversity losses affect this crucial ecosystem process. In a microcosm study, we investigated the effects of litter functional diversity and two major groups of soil macro-detritivores on the mass loss of tree leaf litter mixtures. Furthermore, we tested the effects of litter trait community means and dissimilarity on litter mass loss for seven traits relevant to decomposition. We expected macro-detritivore effects on litter mass loss to be most pronounced in litter mixtures of high functional diversity. We used 24 leaf mixtures differing in functional diversity, which were composed of litter from four species from a pool of 16 common European tree species. Earthworms, isopods, or a combination of both were added to each litter combination for two months. Litter mass loss was significantly higher in the presence of earthworms than in that of isopods, whereas no synergistic effects of macro-detritivore mixtures were found. The effect of functional diversity of the litter material was highest in the presence of both macro-detritivore groups, supporting the notion that litter diversity effects are most pronounced in the presence of different detritivore species. Species-specific litter mass loss was explained by nutrient content, secondary compound concentration, and structural components. Moreover, dissimilarity in N concentrations increased litter mass loss, probably because detritivores having access to nutritionally diverse food sources. Furthermore, strong competition between the two macro-detritivores for soil surface litter resulted in a decrease of survival of both macro-detritivores. These results show that the effects of litter functional diversity on decomposition are contingent upon the macro-detritivore community and composition. We conclude that the temporal dynamics of litter trait diversity effects and their interaction with detritivore diversity are key to advancing our understanding of litter mass loss in nature.

Plant litter functional diversity effects on litter mass loss depend on the macro-detritivore community

PubMed Central

Patoine, Guillaume; Thakur, Madhav P.; Friese, Julia; Nock, Charles; Hönig, Lydia; Haase, Josephine; Scherer-Lorenzen, Michael; Eisenhauer, Nico

2017-01-01

A better understanding of the mechanisms driving litter diversity effects on decomposition is needed to predict how biodiversity losses affect this crucial ecosystem process. In a microcosm study, we investigated the effects of litter functional diversity and two major groups of soil macro-detritivores on the mass loss of tree leaf litter mixtures. Furthermore, we tested the effects of litter trait community means and dissimilarity on litter mass loss for seven traits relevant to decomposition. We expected macro-detritivore effects on litter mass loss to be most pronounced in litter mixtures of high functional diversity. We used 24 leaf mixtures differing in functional diversity, which were composed of litter from four species from a pool of 16 common European tree species. Earthworms, isopods, or a combination of both were added to each litter combination for two months. Litter mass loss was significantly higher in the presence of earthworms than in that of isopods, whereas no synergistic effects of macro-detritivore mixtures were found. The effect of functional diversity of the litter material was highest in the presence of both macro-detritivore groups, supporting the notion that litter diversity effects are most pronounced in the presence of different detritivore species. Species-specific litter mass loss was explained by nutrient content, secondary compound concentration, and structural components. Moreover, dissimilarity in N concentrations increased litter mass loss, probably because detritivores having access to nutritionally diverse food sources. Furthermore, strong competition between the two macro-detritivores for soil surface litter resulted in a decrease of survival of both macro-detritivores. These results show that the effects of litter functional diversity on decomposition are contingent upon the macro-detritivore community and composition. We conclude that the temporal dynamics of litter trait diversity effects and their interaction with detritivore diversity are key to advancing our understanding of litter mass loss in nature. PMID:29180828

Litter chemistry, community shift, and non-additive effects drive litter decomposition changes following invasion by a generalist pathogen

Treesearch

Richard C. Cobb; David M. Rizzo

2016-01-01

Forest pathogens have strong potential to shape ecosystem function by altering litterfall, microclimate, and changing community structure. We quantified changes in litter decomposition from a set of distinct diseases caused by Phytophthora ramorum, an exotic generalist pathogen. Phytophthora ramorum causes leaf blight and...

Radiocesium migration in the litter layer of different forest types in Fukushima, Japan.

PubMed

Kurihara, Momo; Onda, Yuichi; Kato, Hiroaki; Loffredo, Nicolas; Yasutaka, Tetsuo; Coppin, Frederic

2018-07-01

Cesium-137 ( 137 Cs) migration in the litter layer consists of various processes, such as input via throughfall, output via litter decomposition, and input from deeper layers via soil organism activity. We conducted litter bag experiments over 2 years (December 2014-November 2016) to quantify the inputs and outputs of 137 Cs in the litter layer in a Japanese cedar plantation (Cryptomeria japonica) and a mixed broadleaf forest dominated by Quercus serrata located 40 km northwest of the Fukushima Dai-ichi Nuclear Power Plant. The experiments included four conditions, combining contaminated and non-contaminated litter and deeper layer material, and the inputs and outputs were estimated from the combination of 137 Cs increases and decreases in the litter layer under each condition. The 137 Cs dynamics differed between the two forests. In the C. japonica forest, some 137 Cs input via throughfall remained in the litter layer, and downward 137 Cs flux passed through the litter layer was 0.42 (/year).Upward flux of 137 Cs from the deeper layer was very restricted, < 0.017 (/year). In the broadleaf forest, migration of 137 Cs in throughfall into deeper layers was restricted, downward 137 Cs flux was less than 0.003 (/year).Upward input of 137 Cs from the deeper layer was prominent, 0.037 (/year). 137 Cs output via litter decomposition was observed in both forests. The flux in the C. japonica forest was slower than that in the broadleaf forest, 0.12 and 0.15 (/year), respectively. Copyright © 2018 Elsevier Ltd. All rights reserved.

Zinc oxide nanoparticles affect carbon and nitrogen mineralization of Phoenix dactylifera leaf litter in a sandy soil.

PubMed

Rashid, Muhammad Imtiaz; Shahzad, Tanvir; Shahid, Muhammad; Ismail, Iqbal M I; Shah, Ghulam Mustafa; Almeelbi, Talal

2017-02-15

We investigated the impact of zinc oxide nanoparticles (ZnO NPs; 1000mgkg -1 soil) on soil microbes and their associated soil functions such as date palm (Phoenix dactylifera) leaf litter (5gkg -1 soil) carbon and nitrogen mineralization in mesocosms containing sandy soil. Nanoparticles application in litter-amended soil significantly decreased the cultivable heterotrophic bacterial and fungal colony forming units (cfu) compared to only litter-amended soil. The decrease in cfu could be related to lower microbial biomass carbon in nanoparticles-litter amended soil. Likewise, ZnO NPs also reduced CO 2 emission by 10% in aforementioned treatment but this was higher than control (soil only). Labile Zn was only detected in the microbial biomass of nanoparticles-litter applied soil indicating that microorganisms consumed this element from freely available nutrients in the soil. In this treatment, dissolved organic carbon and mineral nitrogen were 25 and 34% lower respectively compared to litter-amended soil. Such toxic effects of nanoparticles on litter decomposition resulted in 130 and 122% lower carbon and nitrogen mineralization efficiency respectively. Hence, our results entail that ZnO NPs are toxic to soil microbes and affect their function i.e., carbon and nitrogen mineralization of applied litter thus confirming their toxicity to microbial associated soil functions. Copyright © 2016 Elsevier B.V. All rights reserved.

C, N and P fertilization in an Amazonian rainforest supports stoichiometric dissimilarity as a driver of litter diversity effects on decomposition.

PubMed

Barantal, Sandra; Schimann, Heidy; Fromin, Nathalie; Hättenschwiler, Stephan

2014-12-07

Plant leaf litter generally decomposes faster as a group of different species than when individual species decompose alone, but underlying mechanisms of these diversity effects remain poorly understood. Because resource C : N : P stoichiometry (i.e. the ratios of these key elements) exhibits strong control on consumers, we supposed that stoichiometric dissimilarity of litter mixtures (i.e. the divergence in C : N : P ratios among species) improves resource complementarity to decomposers leading to faster mixture decomposition. We tested this hypothesis with: (i) a wide range of leaf litter mixtures of neotropical tree species varying in C : N : P dissimilarity, and (ii) a nutrient addition experiment (C, N and P) to create stoichiometric similarity. Litter mixtures decomposed in the field using two different types of litterbags allowing or preventing access to soil fauna. Litter mixture mass loss was higher than expected from species decomposing singly, especially in presence of soil fauna. With fauna, synergistic litter mixture effects increased with increasing stoichiometric dissimilarity of litter mixtures and this positive relationship disappeared with fertilizer addition. Our results indicate that litter stoichiometric dissimilarity drives mixture effects via the nutritional requirements of soil fauna. Incorporating ecological stoichiometry in biodiversity research allows refinement of the underlying mechanisms of how changing biodiversity affects ecosystem functioning. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

VOC emission into the atmosphere by trees and leaf litter in Polish forests

NASA Astrophysics Data System (ADS)

Isidorov, V.; Smolewska, M.; Tyszkiewicz, Z.

2009-04-01

It is generally recognized at present that the vegetation of continents is the principal source of reactive volatile organic compounds (VOC) of the atmosphere. The upper limit of the evaluation of global phytogenic VOC is 1100-1500 Tg/yr (Isidorov, 1990; Guenther et al., 1995). Although these global evaluations showing the place of phytogenic emission among of other VOC sources are important, evaluations for individual countries are also very important. This poster represents the results of the estimation of VOC emission from Polish forests. Calculations took into account the composition and age of forests. According to our estimation, the total VOC emission by the arboreal vegetation differs from 190 to 750 kt/yr, depending of weather conditions in different years. There are only few studies conducted on decaying plant material as a source of atmospheric VOCs, but still they are able to give evidence of the importance of this source. For Polish forests, the litter mass is estimated to be (16-19)106 t/yr. These organic materials undergo decomposition by mesofauna and microorganisms. In these processes volatile organic compounds (VOC) stored in the litter and secondary metabolites of litter-destroying fungi are emitted into the atmosphere. The scale of the phenomenon makes leaf litter an important VOC source in the atmosphere. The filling of numerous gaps in researches of VOC emissions from decomposing leaf litter demands carrying out of long term field experiments in various climatic conditions. In this communication we report also the results of 3.5-year experiment on qualitative and quantitative GC-MS investigations of VOC emitted into the gas phase from leaves litter of some species of deciduous and coniferous trees of Polish forests. Apart from terpenes and their oxygenated derivatives, which are usual in plant tissues, leaf litter intensively emits vast amounts of lower alcohols and carbonyl compounds. We suppose that these volatile substances are products of vital activity of fungi which decompose leaf litter. Verification of the hypothesis was carried out in the frames of a long-term experiment on decomposition of Scots pine and common spruce litter. The experiment was conducted in natural conditions by placing litter bags on undisturbed topsoil in a forest area where pine and spruce trees prevailed. Part of the needles placed were taken out of the litter bags on the 30th, 282nd, 490th, 630th and 920th day of the experiment for subsequent isolation of fungi which colonize the litter (overall there were identified 98 species which belong to 48 genera of fungi). The experiment revealed that species composition of the fungi colonizing pine and spruce litter varies considerably. At the early stages of decomposition, dematiceous hypnomycetes, which belongs to Cladosporum, Alternaria genera as well as Hormonem genus, capable of utilizing pectin, were dominant species. At the later stages they were substituted with phycomycetes (Mucor sp.), ascomycetes (Penicillium sp.) and basidiomycetes (Trichderma sp.), the most significant group of "secondary saprophytes" able to carry out biodegradation of polysaccharides and lignin. In volatile emissions of all the 15 species of fungi there were identified 80 VOCs of different classes: terpene hydrocarbons and their oxygenated derivatives, C6-C14 aliphatic and C6-C10 aromatic hydrocarbons, C1-C8 alcohols, C2-C9 carbonyls, esters, furans, and halocarbons. VOC composition was specific for each fungi species and depended on the litter of a particular tree species from which it had been isolated. For instance, the emission rate of terpenes, alcohols and carbonyl compounds by Trichoderma polysporum isolated from pine and spruce litter was 3-5 times different. Differences in composition of VOCs emitted into the gas phase by "primary" and "secondary" fungi species which colonize pine and spruce litter are also discussed. This work was supported by Grant MNiSW N305 067 32/2411.

Litter mixture dominated by leaf litter of the invasive species, Flaveria bidentis, accelerates decomposition and favors nitrogen release.

PubMed

Li, Huiyan; Wei, Zishang; Huangfu, Chaohe; Chen, Xinwei; Yang, Dianlin

2017-01-01

In natural ecosystems, invasive plant litter is often mixed with that of native species, yet few studies have examined the decomposition dynamics of such mixtures, especially across different degrees of invasion. We conducted a 1-year litterbag experiment using leaf litters from the invasive species Flaveria bidentis (L.) and the dominant co-occurring native species, Setaria viridis (L.). Litters were allowed to decompose either separately or together at different ratios in a mothproof screen house. The mass loss of all litter mixtures was non-additive, and the direction and strength of effects varied with species ratio and decomposition stage. During the initial stages of decomposition, all mixtures had a neutral effect on the mass loss; however, at later stages of decomposition, mixtures containing more invasive litter had synergistic effects on mass loss. Importantly, an increase in F. bidentis litter with a lower C:N ratio in mixtures led to greater net release of N over time. These results highlight the importance of trait dissimilarity in determining the decomposition rates of litter mixtures and suggest that F. bidentis could further synchronize N release from litter as an invasion proceeds, potentially creating a positive feedback linked through invasion as the invader outcompetes the natives for nutrients. Our findings also demonstrate the importance of species composition as well as the identity of dominant species when considering how changes in plant community structure influence plant invasion.

N2-fixing red alder indirectly accelerates ecosystem nitrogen cycling

USGS Publications Warehouse

Perakis, Steven S.; Matkins, Joselin J.; Hibbs, David E.

2012-01-01

Symbiotic N2-fixing tree species can accelerate ecosystem N dynamics through decomposition via direct pathways by producing readily decomposed leaf litter and increasing N supply to decomposers, as well as via indirect pathways by increasing tissue and detrital N in non-fixing vegetation. To evaluate the relative importance of these pathways, we compared three-year decomposition and N dynamics of N2-fixing red alder leaf litter (2.34 %N) to both low-N (0.68 %N) and high-N (1.21 %N) litter of non-fixing Douglas-fir, and decomposed each litter source in four forests dominated by either red alder or Douglas-fir. We also used experimental N fertilization of decomposition plots to assess elevated N availability as a potential mechanism of N2-fixer effects on litter mass loss and N dynamics. Direct effects of N2-fixing red alder on decomposition occurred primarily as faster N release from red alder than Douglas-fir litter, but direct increases in N supply to decomposers via fertilization did not stimulate decomposition of any litter. Fixed N indirectly influenced detrital dynamics by increasing Douglas-fir tissue and litter N concentrations, which accelerated litter N release without accelerating mass loss. By increasing soil N, tissue N, and the rate of N release from litter of non-fixers, we conclude that N2-fixing vegetation can indirectly foster plant-soil feedbacks that contribute to the persistence of elevated N availability in terrestrial ecosystems.

Segregation and Alteration of Phenolic and Aliphatic Components of Root and Leaf Litter by Detritivores and Microbes

NASA Astrophysics Data System (ADS)

Filley, T. R.; Altmann, J.; Szlavecz, K. A.; Kalbitz, K.; Gamblin, D.; Nierop, K.

2012-12-01

The physical and microbial transformation of plant detritus in the litter layer and soil is accompanied by chemical separation of progressively soluble fractions and their movement into the rhizosphere driving subsequent soil processes. We investigated the combined action of specific detritivores, microbial decay, and leaching on the chemical separation of plant aromatic and aliphatic components from root, wood, and leaf tissue using 13C-TMAH thermochemolysis. This method enabled the simultaneous analysis of hydrolyzable tannin and lignin fragments, substituted fatty acids, and condensed tannin composition and revealed process-specific chemical transformations to plant secondary compounds. Long-term incubation and field sampling demonstrated how plant residues are progressively leached of the water soluble, oxidized fragments generated through decay. The residues appeared only slightly altered, in the case of brown rot wood, or enriched in aliphatic fragments, in the case of leaf and root tissue. Water extractable fractions were always selectively dominated by polyphenolics, either as demethylated lignin or tannins, and nearly devoid of aliphatic materials, despite high concentrations in the starting materials. Additionally, for plant materials with high tannin contents, such as pine needles, consumption and passage through some arthropod guts revealed what appeared to be microbially-mediated methylation of phenols, and a loss of tannins in leachates. These findings are indications for an in-situ phenol detoxification mechanism. This research provides important information regarding the links between biochemical decay and the chemical nature of organic matter removed and remaining in the soil profile.

Decomposition and nitrogen dynamics of 15N-labeled leaf, root, and twig litter in temperate coniferous forests

Treesearch

T.L. van Huysen; M.E. Harmon; S.S. Perakis; H. Chen

2013-01-01

Litter nutrient dynamics contribute significantly to biogeochemical cycling in forest ecosystems. We examined how site environment and initial substrate quality influence decomposition and nitrogen (N) dynamics of multiple litter types. A 2.5-year decomposition study was installed in the Oregon Coast Range and West Cascades using 15N-labeled...

Effects of river flow regime on cottonwood leaf litter dynamics in semi-arid northwestern Colorado

USGS Publications Warehouse

Andersen, D.C.; Nelson, S.M.

2003-01-01

We compared production and breakdown of Fremont cottonwood (Populus deltoides wislizenii) leaf litter at matched floodplain sites on the regulated Green River and unregulated Yampa River in semi-arid northwestern Colorado. Litter production under trees was similar at sites in 1999 (250 g/m2, oven-dry) but lower in 2000 (215 and 130 g/m2), a drought year that also featured an outbreak of defoliating beetles at the Yampa River site. Our production values were similar to the few others reported for riparian forests within semi-arid or arid areas. Leaf litter in portions of the floodplain not inundated during the spring flood lost organic matter at the same rate as leaves placed in upland sites in 1998 and 2000: 35 to 50% of organic matter during an approximately 160-day spring and summer period. Inundated litter lost 55 to 90% of its organic matter during the same period. Organic matter loss from inundated leaves increased with duration of inundation and with deposition of fine sediment. Pooled across locations, leafpack data suggested that nitrogen concentration (mg N/kg organic matter) increased until about 65% of the initial organic matter was lost. This increase likely reflected the buildup of microbial decomposer populations. The role of insects and other macroinvertebrates in litter breakdown apparently was minor at both sites. Large spatial and temporal variation in litter dynamics in aridland floodplain settings is ensured by microtopographic variation in the alluvial surface coupled with year-to-year variation associated with most natural flood regimes. Factors reducing flood flow frequency or magnitude will reduce overall breakdown rates on the floodplain towards those found in drier upland environments.

Contrasting patterns of litterfall seasonality and seasonal changes in litter decomposability in a tropical rainforest region

NASA Astrophysics Data System (ADS)

Parsons, S. A.; Valdez-Ramirez, V.; Congdon, R. A.; Williams, S. E.

2014-06-01

The seasonality of litter inputs in forests has important implications for understanding ecosystem processes and biogeochemical cycles. We quantified the drivers of seasonality in litterfall and leaf decomposability, using plots throughout the Australian wet tropical region. Litter fell mostly in the summer (wet, warm) months in the region, but other peaks occurred throughout the year. Litterfall seasonality was modelled well with the level of deciduousness of the site (plots with more deciduous species had lower seasonality than evergreen plots), temperature (higher seasonality in the uplands), disturbance (lower seasonality with more early secondary species) and soil fertility (higher seasonality with higher N : P/P limitation) (SL total litterfall model 1 = deciduousness + soil N : P + early secondary sp: r2 = 0.63, n = 30 plots; model 2 = temperature + early secondary sp. + soil N : P: r2 = 0.54, n = 30; SL leaf = temperature + early secondary sp. + rainfall seasonality: r2 = 0.39, n = 30). Leaf litter decomposability was lower in the dry season than in the wet season, driven by higher phenolic concentrations in the dry, with the difference exacerbated particularly by lower dry season moisture. Our results are contrary to the global trend for tropical rainforests; in that seasonality of litterfall inputs were generally higher in wetter, cooler, evergreen forests, compared to generally drier, warmer, semi-deciduous sites that had more uniform monthly inputs. We consider this due to more diverse litter shedding patterns in semi-deciduous and raingreen rainforest sites, and an important consideration for ecosystem modellers. Seasonal changes in litter quality are likely to have impacts on decomposition and biogeochemical cycles in these forests due to the litter that falls in the dry being more recalcitrant to decay.

Contrasting patterns of litterfall seasonality and seasonal changes in litter decomposability in a tropical rainforest region

NASA Astrophysics Data System (ADS)

Parsons, S. A.; Valdez-Ramirez, V.; Congdon, R. A.; Williams, S. E.

2014-09-01

The seasonality of litter inputs in forests has important implications for understanding ecosystem processes and biogeochemical cycles. We quantified the drivers of seasonality in litterfall and leaf decomposability using plots throughout the Australian wet tropical region. Litter fell mostly in the summer (wet, warm) months in the region, but other peaks occurred throughout the year. Litterfall seasonality was modelled well with the level of deciduousness of the site (plots with more deciduous species had lower seasonality than evergreen plots), temperature (higher seasonality in the uplands), disturbance (lower seasonality with more early secondary species) and soil fertility (higher seasonality with higher N : P/P limitation) (SL total litterfall model 1 = deciduousness + soil N : P + early secondary sp.: r2 = 0.63, n = 30; model 2 = temperature + early secondary sp. + soil N : P: r2 = 0.54, n = 30; SL leaf = temperature + early secondary sp. + rainfall seasonality: r2 = 0.39, n = 30). Leaf litter decomposability was lower in the dry season than in the wet season, driven by higher phenolic concentrations in the dry, with the difference exacerbated particularly by lower dry season moisture. Our results are contrary to the global trend for tropical rainforests; in that seasonality of litterfall input was generally higher in wetter, cooler, evergreen forests, compared to generally drier, warmer, semi-deciduous sites that had more uniform monthly inputs. We consider this due to more diverse litter shedding patterns in semi-deciduous and raingreen rainforest sites, and an important consideration for ecosystem modellers. Seasonal changes in litter quality are likely to have impacts on decomposition and biogeochemical cycles in these forests due to the litter that falls in the dry season being more recalcitrant to decay.

Light limitation and litter of an invasive clonal plant, Wedelia trilobata, inhibit its seedling recruitment

PubMed Central

Qi, Shan-Shan; Dai, Zhi-Cong; Miao, Shi-Li; Zhai, De-Li; Si, Chun-Can; Huang, Ping; Wang, Rui-Ping; Du, Dao-Lin

2014-01-01

Background and Aims Invasive clonal plants have two reproduction patterns, namely sexual and vegetative propagation. However, seedling recruitment of invasive clonal plants can decline as the invasion process proceeds. For example, although the invasive clonal Wedelia trilobata (Asteraceae) produces numerous seeds, few seedlings emerge under its dense population canopy in the field. In this study it is hypothesized that light limitation and the presence of a thick layer of its own litter may be the primary factors causing the failure of seedling recruitment for this invasive weed in the field. Methods A field survey was conducted to determine the allocation of resources to sexual reproduction and seedling recruitment in W. trilobata. Seed germination was also determined in the field. Effects of light and W. trilobata leaf extracts on seed germination and seedling growth were tested in the laboratory. Key Results Wedelia trilobata blooms profusely and produces copious viable seeds in the field. However, seedlings of W. trilobata were not detected under mother ramets and few emerged seedlings were found in the bare ground near to populations. In laboratory experiments, low light significantly inhibited seed germination. Leaf extracts also decreased seed germination and inhibited seedling growth, and significant interactions were found between low light and leaf extracts on seed germination. However, seeds were found to germinate in an invaded field after removal of the W. trilobata plant canopy. Conclusions The results indicate that lack of light and the presence of its own litter might be two major factors responsible for the low numbers of W. trilobata seedlings found in the field. New populations will establish from seeds once the limiting factors are eliminated, and seeds can be the agents of long-distance dispersal; therefore, prevention of seed production remains an important component in controlling the spread of this invasive clonal plant. PMID:24825293

Flood flows, leaf breakdown, and plant-available nitrogen on a dryland river floodplain

USGS Publications Warehouse

Andersen, Douglas C.; Nelson, S. Mark; Binkley, Dan

2003-01-01

We tested the hypothesis that decomposition in flood-inundated patches of riparian tree leaf litter results in higher plant-available nitrogen in underlying, nutrient-poor alluvium. We used leafpacks (n = 56) containing cottonwood (Populus deltoides ssp. wislizenii) leaf litter to mimic natural accumulations of leaves in an experiment conducted on the Yampa River floodplain in semi-arid northwestern Colorado, USA. One-half of the leafpacks were set on the sandy alluvial surface, and one-half were buried 5 cm below the surface. The presence of NO3− and NH4+ presumed to result from a leafpack's submergence during the predictable spring flood pulse was assessed using an ion-exchange resin bag (IER) placed beneath each leafpack and at control locations. Leafpacks and IERs were collected one week after flood peak (71 days total exposure) at half the stations; the remainder were collected three weeks later (93 days exposure). A multi-peaked spring flood with above-average maximum discharge inundated leafpacks for total time periods ranging from 133 to 577 hours. Litter lost from 43 to 68 percent of its initial organic matter (OM) content. Organic matter loss increased with total time inundated and total time of exposure on the floodplain. Burial retarded OM loss if the total time inundated was relatively long, and substrate texture (sand vs. silt) affected OM loss in a complex manner through interactions with total time inundated and total time of exposure. No pulse of N attributable to leaf breakdown was detected in the IERs, and leafpack litter showed no net change in the mass of nitrogen present. Patterns of leafpack and IER nitrogen levels suggested that litter removed N from floodwater and thereby reduced N availability in underlying sediment. Immobilization of floodwater-N by litter and N mineralization outside the flood period may be important components of N flux in semi-arid and arid floodplain environments.

Test of validity of a dynamic soil carbon model using data from leaf litter decomposition in a West African tropical forest

NASA Astrophysics Data System (ADS)

Guendehou, G. H. S.; Liski, J.; Tuomi, M.; Moudachirou, M.; Sinsin, B.; Mäkipää, R.

2013-05-01

We evaluated the applicability of the dynamic soil carbon model Yasso07 in tropical conditions in West Africa by simulating the litter decomposition process using as required input into the model litter mass, litter quality, temperature and precipitation collected during a litterbag experiment. The experiment was conducted over a six-month period on leaf litter of five dominant tree species, namely Afzelia africana, Anogeissus leiocarpa, Ceiba pentandra, Dialium guineense and Diospyros mespiliformis in a semi-deciduous vertisol forest in Southern Benin. Since the predictions of Yasso07 were not consistent with the observations on mass loss and chemical composition of litter, Yasso07 was fitted to the dataset composed of global data and the new experimental data from Benin. The re-parameterized versions of Yasso07 had a good predictive ability and refined the applicability of the model in Benin to estimate soil carbon stocks, its changes and CO2 emissions from heterotrophic respiration as main outputs of the model. The findings of this research support the hypothesis that the high variation of litter quality observed in the tropics is a major driver of the decomposition and needs to be accounted in the model parameterization.

Soil communities and plant litter decomposition as influenced by forest debris: Variation across tropical riparian and upland sites.

Treesearch

Honghua Ruana; Yiqing Lib; Xiaoming Zouc

2005-01-01

Forest debris on ground surface can interact with soil biota and consequently change ecosystem processes across heterogeneous landscape. We examined the interactions between forest debris and litter decomposition in riparian and upland sites within a tropical wet forest. Our experiment included control and debris-removal treatments. Debris-removal reduced leaf litter...

Terrestrial litter inputs as determinants of food quality of organic matter in a forest stream

Treesearch

J.L. Meyer; C. Hax; J.B. Wallace; S.L. Eggert; J.R. Webster

2000-01-01

Inputs of leaf litter and other organic matter from the catchment exceed autochthonous production and provide an important food resource in most streams (WEBSTER & MEYER 1997, ANDERSON & SEDELL 1979). An experimental long-term exclusion of terrestrial litter inputs to a forested headwater stream (WALLACE et al. 1997) provided an opportunity to determine if the...

Molecular Assessment of litter decay dynamics across old and young forest sites

NASA Astrophysics Data System (ADS)

Filley, T. R.; Crow, S.; Gamblin, D.; McCormick, M.; Whigham, D.; Taylor, D. L.

2006-12-01

The response of soil organic matter pools to changes in litter input, land cover, and ýinvertebrate activity is a research area of intensive study given the proposed impacts that ýrising CO2 and surface temperatures may have on forest productivity and distribution of ýinvasive species. In a mixed deciduous forest at the Smithsonian Environmental ýResearch Center litter amendment plots were established in old (120-150 y) and young ýý(50-70 y) forests. In May 2004, six plots were amended with locally collected ýLirodendron tulipifera wood (chipped) and leaves. At the same time, leaf and wood litter ýbag decomposition experiments on the sites were also started. Changes in the ýconcentration and composition of biopolymers, e.g. lignin and cutin/suberin, after ýapproximately four months of decay were tracked by alkaline CuO extraction. Resultant ýleaf and wood litter in the surface amendments was distinct between age groupings. ýYoung sites exhibited the greatest change in chemical character showing increased lignin ýand decreased cutin/suberin resulting in a cutin-poor residue. Minor changes to ýbiopolymer character were observed in older sites with residues exhibiting small but ýopposite trends to the young sites. In contrast, the litter bag studies exhibited little to no ývariation in chemistry with age of stand; although, generally leaf litter showed the ýgreatest age-related effect. These patterns in litter decay are consistent with both ýmicrobial activity and relative biomass of invasive earthworms; young forests exhibit ýrelatively higher activity of both phenol oxidase and B-glucosidase in the soil (0-5 cm) ýplots and greater biomass and relative abundance invasive earthworms. These results are ýimportant as they show how stand age and the presence of invertebrate species may have ýimportant controls on the impact that many global change drivers may have on forest soil ýand carbon exchange dynamics.ý

Impacts of leaves, roots, and earthworms on soil organic matter composition and distribution in sycamore maple stands

NASA Astrophysics Data System (ADS)

Rivera, N.; Mueller, K. E.; Mueller, C. W.; Oleksyn, J.; Hale, C.; Freeman, K. H.; Eissenstat, D.

2009-12-01

The relative contributions of leaf and root material to soil organic matter (SOM) are poorly understood despite the importance of constraining SOM sources to conceptual and numeric models of SOM dynamics. Selective ingestion and bioturbation of litter and soil by earthworms can alter the fate and spatial distribution of OM in soils, including stabilization pathways of leaf and root litter. However, studies on the contributions of leaves, roots, and earthworms to SOM dynamics are rare. In 3 stands of sycamore maple (Acer pseudoplatanus) with minimal O horizon development and high earthworm activity, we sampled surface litter (> 2 mm) from the Oi horizon, fine roots (< 2 mm), bulk mineral soils (0-20 cm depth), and earthworm casts from Lumbricus terrestris middens. The chemical composition of these samples was estimated by wet-chemical degradation followed by GC-MS analysis. In addition, elemental analyses (C and N) were performed on bulk soils and earthworm casts, before and after physical fractionation by means of particle size and density. Relative to bulk soils, earthworm casts were highly enriched in organic matter, dominated by large particulate OM, and had lower acid to aldehyde ratios among lignin monomers (a proxy for extent of decomposition), confirming that L. terrestris casts stabilize recent plant litter inputs. Maple fine roots and surface litter were distinguished by different profiles of carboxylic acids estimated by GC-MS, facilitating interpretation of OM sources in bulk soil and earthworm casts. Earthworm casts were characterized by a distribution of carboxylic acids similar to that of surface litter while bulk soils had a carboxylic acid profile much closer to that of roots. These results confirm that L. terrestris is primarily a surface, leaf feeder and suggest that OM in the bulk soil may be dominated by root inputs. In bulk soils, the ratio of lignin to hydroxy- and diacids derived from suberin and cutin was low relative to plant litter, confirming the often-observed selective preservation of aliphatic over aromatic biomolecules. The ratio of lignin to cutin/suberin acids in earthworm casts was also low; based on the minimal extent of decomposition in casts evident by lignin acid to aldehyde ratios, we attribute this to selective ingestion by L. terrestris of leaf litter rich in aliphatic biomolecules at the expense of woody debris and petioles rich in lignin, rather than selective preservation.

Laboratory and Airborne BRDF Analysis of Vegetation Leaves and Soil Samples

NASA Technical Reports Server (NTRS)

Georgiev, Georgi T.; Gatebe, Charles K.; Butler, James J.; King, Michael D.

2008-01-01

Laboratory-based Bidirectional Reflectance Distribution Function (BRDF) analysis of vegetation leaves, soil, and leaf litter samples is presented. The leaf litter and soil samples, numbered 1 and 2, were obtained from a site located in the savanna biome of South Africa (Skukuza: 25.0degS, 31.5degE). A third soil sample, number 3, was obtained from Etosha Pan, Namibia (19.20degS, 15.93degE, alt. 1100 m). In addition, BRDF of local fresh and dry leaves from tulip tree (Liriodendron tulipifera) and acacia tree (Acacia greggii) were studied. It is shown how the BRDF depends on the incident and scatter angles, sample size (i.e. crushed versus whole leaf,) soil samples fraction size, sample status (i.e. fresh versus dry leaves), vegetation species (poplar versus acacia), and vegetation s biochemical composition. As a demonstration of the application of the results of this study, airborne BRDF measurements acquired with NASA's Cloud Absorption Radiometer (CAR) over the same general site where the soil and leaf litter samples were obtained are compared to the laboratory results. Good agreement between laboratory and airborne measured BRDF is reported.

Decomposition of birch leaves in heavily polluted industrial barrens: relative importance of leaf quality and site of exposure.

PubMed

Kozlov, Mikhail V; Zvereva, Elena L

2015-07-01

The decrease in litter decomposition rate in polluted habitats is well documented, but the factors that explain the observed variation in the magnitude of this pollution effect on litter decomposition remain poorly understood. We explored effects of environmental conditions and leaf quality on decomposition rate of mountain birch (Betula pubescens ssp. czerepanovii) leaves in a heavily polluted industrial barren near the nickel-copper smelter at Monchegorsk. Litter bags filled with leaves collected from two heavily polluted barren sites and from two control forest sites were buried at 2.5-cm depth and exposed for 2 and 4 years at each of these four sites. The relative mass loss of native leaves in the industrial barren during 2 years of exposure was reduced to 49% of the loss observed in the unpolluted forest. We found a similar reduction in mass loss when leaves from control sites were exposed to polluted sites and when leaves from polluted sites were exposed to control sites. We conclude that the reduction in leaf litter decomposition in an industrial barren is caused by pollution-induced changes in both environmental conditions and leaf quality. This reduction is much smaller than expected, given the four-fold decrease in soil microbial activity and nearly complete extinction of saprophagous invertebrates in the polluted soil. We suggest that a longer snowless period and higher spring and summer temperatures at the barren sites have partially counterbalanced the adverse effects caused by the toxicity of metal pollutants.

Seasonal and local differences in leaf litter flammability of six Mediterranean tree species.

PubMed

Kauf, Zorica; Fangmeier, Andreas; Rosavec, Roman; Španjol, Željko

2015-03-01

One of the suggested management options for reducing fire danger is the selection of less flammable plant species. Nevertheless, vegetation flammability is both complex and dynamic, making identification of such species challenging. While large efforts have been made to connect plant traits to fire behavior, seasonal changes and within species variability of traits are often neglected. Currently, even the most sophisticated fire danger systems presume that intrinsic characteristics of leaf litter stay unchanged, and plant species flammability lists are often transferred from one area to another. In order to assess if these practices can be improved, we performed a study examining the relationship between morphological characteristics and flammability parameters of leaf litter, thereby taking into account seasonal and local variability. Litter from six Mediterranean tree species was sampled throughout the fire season from three different locations along a climate gradient. Samples were subjected to flammability testing involving an epiradiator operated at 400 °C surface temperature with 3 g sample weight. Specific leaf area, fuel moisture content, average area, and average mass of a single particle had significant influences on flammability parameters. Effects of sampling time and location were significant as well. Due to the standardized testing conditions, these effects could be attributed to changes in intrinsic characteristics of the material. As the aforementioned effects were inconsistent and species specific, these results may potentially limit the generalization of species flammability rankings. Further research is necessary in order to evaluate the importance of our findings for fire danger modeling.

Role of allelopathy as a possible factor associated with the rising dominance ofBunias orientalis L. (Brassicaceae) in some native plant assemblages.

PubMed

Dietz, H; Steinlein, T; Winterhalter, P; Ullmann, I

1996-10-01

Leaf extracts ofBunias orientalis were shown to inhibit seed germination of a variety of cultivar plant species and of species cooccurring withB. orientalis in the field. Root exudate solutions and leaf litter leachates ofB. orientalis were tested for their allelopathic activity using seedling growth assays. Additionally, in comparative seedling growth assays soil cores removed from denseB. orientalis stands were tested bimonthly for elevated allelopathic effects. The impact of root exudates on seedling growth was generally weak and varied between species. Similar results were obtained for the effect ofB. orientalis leaf litter leachates on seedlings grown in sand culture relative to the effect of leaf litter leachates of a plant species mixture. When soil as a growth substrate was used, no consistent differences in seedling growth were obtained between the two litter leachate treatments. In the soil core experiment seedlings grown in soil cores collected from a denseB. orientalis stand unexpectedly showed better performance than seedlings grown in soil cores collected from a nearby mixed plant stand withoutB. orientalis, at least in early spring and late autumn. Predominating nutrient effects are, therefore, assumed to conceal a potentially increased allelopathic effect of soil beneath denseB. orientalis stands. It is concluded that other factors than allelopathy must be investigated to explain the rapid establishment of dense stands of this alien plant species.

No effect of Bt-transgenic rice litter on the meiobenthos community in field ditches.

PubMed

Liu, Yongbo; Jiang, Wanxiang; Liang, Yuyong; Zhao, Caiyun; Li, Junsheng

2017-06-01

The non-target effect of Bacillus thuringiensis (Bt) toxins in aquatic ecosystems is crucial to improve the present assessment of Bt-transgenic plants, particularly where crops are cultivated near aquatic ecosystems. We conducted decomposition experiments during two growing seasons to determine the effects of Bt-transgenic rice litter with and without insecticide application on the meiobenthos communities in a field ditch. The community composition of meiobenthos colonised on leaf litter was not significantly different between Bt and non-Bt rice. The abundance of meiobenthos colonising leaves differed between insecticide application and control, and this insecticide effect interacted with rice type. No Bt toxin was detected in field ditch water. Leaf decomposition and nutrient content were comparable for both Bt and non-Bt rice with or without insecticide application. Bt-transgenic rice litter had no effect on the meiobenthos community composition in field ditches, but the chronic persistence of transgenic litter in nature needs to be taken into account at large scales in aquatic ecosystems. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Synergistic effects of the invasive Chinese tallow (Triadica sebifera) and climate change on aquatic amphibian survival

PubMed Central

Saenz, Daniel; Fucik, Erin M; Kwiatkowski, Matthew A

2013-01-01

Changes in climate and the introduction of invasive species are two major stressors to amphibians, although little is known about the interaction between these two factors with regard to impacts on amphibians. We focused our study on an invasive tree species, the Chinese tallow (Triadica sebifera), that annually sheds its leaves and produces leaf litter that is known to negatively impact aquatic amphibian survival. The purpose of our research was to determine whether the timing of leaf fall from Chinese tallow and the timing of amphibian breeding (determined by weather) influence survival of amphibian larvae. We simulated a range of winter weather scenarios, ranging from cold to warm, by altering the relative timing of when leaf litter and amphibian larvae were introduced into aquatic mesocosms. Our results indicate that amphibian larvae survival was greatly affected by the length of time Chinese tallow leaf litter decomposes in water prior to the introduction of the larvae. Larvae in treatments simulating warm winters (early amphibian breeding) were introduced to the mesocosms early in the aquatic decomposition process of the leaf litter and had significantly lower survival compared with cold winters (late amphibian breeding), likely due to significantly lower dissolved oxygen levels. Shifts to earlier breeding phenology, linked to warming climate, have already been observed in many amphibian taxa, and with most climate models predicting a significant warming trend over the next century, the trend toward earlier breeding should continue if not increase. Our results strongly suggest that a warming climate can interact with the effects of invasive plant species, in ways we have not previously considered, to reduce the survival of an already declining group of organisms. PMID:24363907

Synergistic effects of the invasive Chinese tallow (Triadica sebifera) and climate change on aquatic amphibian survival.

PubMed

Saenz, Daniel; Fucik, Erin M; Kwiatkowski, Matthew A

2013-11-01

Changes in climate and the introduction of invasive species are two major stressors to amphibians, although little is known about the interaction between these two factors with regard to impacts on amphibians. We focused our study on an invasive tree species, the Chinese tallow (Triadica sebifera), that annually sheds its leaves and produces leaf litter that is known to negatively impact aquatic amphibian survival. The purpose of our research was to determine whether the timing of leaf fall from Chinese tallow and the timing of amphibian breeding (determined by weather) influence survival of amphibian larvae. We simulated a range of winter weather scenarios, ranging from cold to warm, by altering the relative timing of when leaf litter and amphibian larvae were introduced into aquatic mesocosms. Our results indicate that amphibian larvae survival was greatly affected by the length of time Chinese tallow leaf litter decomposes in water prior to the introduction of the larvae. Larvae in treatments simulating warm winters (early amphibian breeding) were introduced to the mesocosms early in the aquatic decomposition process of the leaf litter and had significantly lower survival compared with cold winters (late amphibian breeding), likely due to significantly lower dissolved oxygen levels. Shifts to earlier breeding phenology, linked to warming climate, have already been observed in many amphibian taxa, and with most climate models predicting a significant warming trend over the next century, the trend toward earlier breeding should continue if not increase. Our results strongly suggest that a warming climate can interact with the effects of invasive plant species, in ways we have not previously considered, to reduce the survival of an already declining group of organisms.

Emissions of biogenic volatile organic compounds from litter are coupled with changes in the microbial community composition

NASA Astrophysics Data System (ADS)

Hagel Svendsen, Sarah; Schostag, Morten; Voriskova, Jana; Kramshøj, Magnus; Priemé, Anders; Suhr Jacobsen, Carsten; Rinnan, Riikka

2017-04-01

Emissions of biogenic volatile organic compounds (BVOCs) from natural ecosystems have significant impact on atmospheric chemistry and belowground chemical processes. Most attention has been given to emissions from plants. However, several studies have found that soil, and especially the decomposing leaf and needle litter, emits substantial amounts of BVOCs. The contribution of litter to ecosystem BVOC emissions may be increasingly significant in the Arctic, where the living plant biomass is low, and the amount of litter increasing due to the expansion of deciduous vegetation in response to climate change. It is known that the types and amounts of BVOCs emitted from the soil are highly dependent on the microbial community composition and the type of substrate. In this study we measured emissions of BVOCs from the leaf litter of common arctic plant species at different temperatures. The BVOC measurements were coupled with an analysis of the relative abundance of dominating bacterial species (determined as operational taxonomic units, OTUs). Leaf litter from evergreen Cassiope tetragona and two species of deciduous Salix were collected from two arctic locations; one in the High Arctic and one in the Low Arctic. The litter was incubated in dark at 5 ?C. Over an eight week period the temperature was increased 7 ?C every two weeks, giving temperature incubations at 5 ?C, 12 ?C, 19 ?C and 26 ?C. Emissions of BVOCs from the litter were sampled in adsorbent cartridges weekly and analyzed using gas chromatography-mass spectrometry. The relative abundance of bacteria was determined at the end of the incubation at each temperature using DNA sequencing. Results showed that emissions of BVOCs belonging to different chemical functional groups responded differently to increasing temperatures and were highly dependent on the type of substrate. For instance, terpenoid emissions from the Cassiope litter increased with increasing temperature, whereas the emissions from the Salix litter decreased. Likewise, the relative abundance of bacteria depended on temperature and the type of substrate. Especially the actinobacteria showed strong increasing trends with increasing temperature in the Salix litter. Acidobacteria had much higher relative abundance in the Cassiope litter than in the Salix litter. Multivariate analyses were used to assess potential links between the BVOC and bacterial abundance datasets. Similar patterns in the BVOC emissions and bacterial community composition at different temperatures and for different substrates suggest that the differences in BVOC emissions, at least to some extent, are driven by changes in the microbial community composition.

Land use not litter quality is a stronger driver of decomposition in hyperdiverse tropical forest.

PubMed

Both, Sabine; Elias, Dafydd M O; Kritzler, Ully H; Ostle, Nick J; Johnson, David

2017-11-01

In hyperdiverse tropical forests, the key drivers of litter decomposition are poorly understood despite its crucial role in facilitating nutrient availability for plants and microbes. Selective logging is a pressing land use with potential for considerable impacts on plant-soil interactions, litter decomposition, and nutrient cycling. Here, in Borneo's tropical rainforests, we test the hypothesis that decomposition is driven by litter quality and that there is a significant "home-field advantage," that is positive interaction between local litter quality and land use. We determined mass loss of leaf litter, collected from selectively logged and old-growth forest, in a fully factorial experimental design, using meshes that either allowed or precluded access by mesofauna. We measured leaf litter chemical composition before and after the experiment. Key soil chemical and biological properties and microclimatic conditions were measured as land-use descriptors. We found that despite substantial differences in litter quality, the main driver of decomposition was land-use type. Whilst inclusion of mesofauna accelerated decomposition, their effect was independent of land use and litter quality. Decomposition of all litters was slower in selectively logged forest than in old-growth forest. However, there was significantly greater loss of nutrients from litter, especially phosphorus, in selectively logged forest. The analyses of several covariates detected minor microclimatic differences between land-use types but no alterations in soil chemical properties or free-living microbial composition. These results demonstrate that selective logging can significantly reduce litter decomposition in tropical rainforest with no evidence of a home-field advantage. We show that loss of key limiting nutrients from litter (P & N) is greater in selectively logged forest. Overall, the findings hint at subtle differences in microclimate overriding litter quality that result in reduced decomposition rates in selectively logged forests and potentially affect biogeochemical nutrient cycling in the long term.

Experimental evaluation of the impact of maternal consumption of aqueous leaf extract of Hybanthus enneaspermus on pregnancy in Sprague Dawley rats.

PubMed

Olubajo, Awobajo Funmileyi; Adefunke, Adegoke Olufeyisipe; Olubusola, Iranloye Bolanle; Ibilola, Olatunji-Bello Ibiyemi

2013-01-01

The impact of aqueous leaf extract of Hybanthus enneaspermus (HEaq) on pregnancy factors and litter survival was investigated in Sprague Dawley (SD) rat. Control group received distilled water while the test group received 2g/kg body weight of HEaq orally. Blood samples were collected on days one and twenty of pregnancy for total blood count, serum thyroid hormone, thyroid stimulating hormone (TSH) and thyrotropin releasing hormone (TRH) assay. Half the number of rats in each group was sacrificed on day nineteen of pregnancy and the placenta and foetus were removed and weighed. The second half carried their pregnancy to term. Number and weights of litter were recorded at birth and the litter were also subjected to righting reflex test. Post-natal survival rate was determined for each group while effect of HEaq was also examined in-vivo on the activities of pregnant myometrial muscle. HEaq significantly decreased (p<0.05) foetal weight, placenta weight, foetal growth and survival, number and weights of litter at birth, maternal serum triiodotyroxine T3 and TSH level. Mean corpuscular haemoglobin, white blood cell count, platelet count and lipid profile were significantly increased (P<0.05). HEaq increased the frequency and percentage contraction of gravid myometrial muscle in a dose dependent manner. Maternal consumption of aqueous leaf extract of Hybanthus enneaspermus adversely affected pregnancy and development of the foetus, as it precipitated resorption of developing foetus and reduced size and weight of litter at term.

Headwater riparian invertebrate communities associated with red alder and conifer wood and leaf litter in southeastern Alaska

USGS Publications Warehouse

LeSage, C.M.; Merritt, R.W.; Wipfli, M.S.

2005-01-01

We examined how management of young upland forests in southeastern Alaska affect riparian invertebrate taxa richness, density, and biomass, in turn, potentially influencing food abundance for fish and wildlife. Southeastern Alaska forests are dominated by coniferous trees including Sitka spruce (Picea sitchensis (Bong.) Carr.), western hemlock (Tsuga heterophylla (Raf.) Sarg.), with mixed stands of red cedar (Thuja plicata Donn.). Red alder (Alnus rubra Bong.) is hypothesized to influence the productivity of young-growth conifer forests and through forest management may provide increased riparian invertebrate abundance. To compare and contrast invertebrate densities between coniferous and alder riparian habitats, leaf litter and wood debris (early and late decay classes) samples were collected along eleven headwater streams on Prince of Wales Island, Alaska, during the summers of 2000 and 2001. Members of Acarina and Collembola were the most abundant taxa collected in leaf litter with alder litter having significantly higher mean taxa richness than conifer litter. Members of Acarina were the most abundant group collected on wood debris and alder wood had significantly higher mean taxa richness and biomass than conifer wood. Alder wood debris in more advanced decay stages had the highest mean taxa richness and biomass, compared to other wood types, while conifer late decay wood debris had the highest densities of invertebrates. The inclusion of alder in young-growth conifer forests can benefit forest ecosystems by enhancing taxa richness and biomass of riparian forest invertebrates. ?? 2005 by the Northwest Scientific Association. All rights reserved.

Does leaf chemistry differentially affect breakdown in tropical vs temperate streams? Importance of standardized analytical techniques to measure leaf chemistry

Treesearch

Marcelo Ard& #243; n; Catherine M. Pringle; Susan L. Eggert

2009-01-01

Comparisons of the effects of leaf litter chemistry on leaf breakdown rates in tropical vs temperate streams are hindered by incompatibility among studies and across sites of analytical methods used to measure leaf chemistry. We used standardized analytical techniques to measure chemistry and breakdown rate of leaves from common riparian tree species at 2 sites, 1...

Assessing the Effect of Litter Species on the Dynamic of Bacterial and Fungal Communities during Leaf Decomposition in Microcosm by Molecular Techniques

PubMed Central

Xu, Wenjing; Shi, Lingling; Chan, Onchim; Li, Jiao; Casper, Peter; Zou, Xiaoming

2013-01-01

Although bacteria and fungi are well-known to be decomposers of leaf litter, few studies have examined their compositions and diversities during the decomposition process in tropical stream water. Xishuangbanna is a tropical region preserving one of the highest floristic diversity areas in China. In this study, leaf litter of four dominant plant species in Xishuangbanna was incubated in stream water for 42 days during which samples were taken regularly. Following DNA extraction, PCR-DGGE (denaturing gradient gel electrophoresis) and clone-sequencing analyses were performed using bacterial and fungal specific primers. Leaf species have slightly influences on bacterial community rather than fungal community. The richness and diversity of bacteria was higher than that of fungi, which increased towards the end of the 42-day-incubation. The bacterial community was initially more specific upon the type of leaves and gradually became similar at the later stage of decomposition with alpha-proteobacteria as major component. Sequences affiliated to methanotrophs were obtained that indicates potentially occurrence of methane oxidation and methanogenesis. For the fungal community, sequences affiliated to Aspergillus were predominant at the beginning and then shifted to Pleosporales. Our results suggest that the microorganisms colonizing leaf biofilm in tropical stream water were mostly generalists that could exploit the resources of leaves of various species equally well. PMID:24367682

The influence of leaf morphology on litter flammability and its utility for interpreting palaeofire

PubMed Central

2016-01-01

Studies of palaeofire rely on quantifying the abundance of fossil charcoals in sediments to estimate changes in fire activity. However, gaining an understanding of the behaviour of palaeofires is also essential if we are to determine the palaeoecological impact of wildfires. Here, I use experimental approaches to explore relationships between litter fire behaviour and leaf traits that are observable in the fossil record. Fire calorimetry was used to assess the flammability of 15 species of conifer litter and indicated that leaf morphology related to litter bulk density and fuel load that determined the duration of burning and the total energy released. These data were applied to a fossil case study that couples estimates of palaeolitter fire behaviour to charcoal-based estimates of fire activity and observations of palaeoecological changes. The case study reveals that significant changes in fire activity and behaviour likely fed back to determine ecosystem composition. This work highlights that we can recognize and measure plant traits in the fossil record that relate to fire behaviour and therefore that further research is warranted towards estimating palaeofire behaviour as it can enhance our ability to interpret the palaeoecological impact of palaeofires throughout Earth's long evolutionary history. This article is part of the themed issue ‘The interaction of fire and mankind’. PMID:27216520

Exposure to the leaf litter microbiome of healthy adults protects seedlings from pathogen damage.

PubMed

Christian, Natalie; Herre, Edward Allen; Mejia, Luis C; Clay, Keith

2017-07-12

It is increasingly recognized that microbiota affect host health and physiology. However, it is unclear what factors shape microbiome community assembly in nature, and how microbiome assembly can be manipulated to improve host health. All plant leaves host foliar endophytic fungi, which make up a diverse, environmentally acquired fungal microbiota. Here, we experimentally manipulated assembly of the cacao tree ( Theobroma cacao ) fungal microbiome in nature and tested the effect of assembly outcome on host health. Using next-generation sequencing, as well as culture-based methods coupled with Sanger sequencing, we found that manipulating leaf litter exposure and location within the forest canopy significantly altered microbiome composition in cacao. Exposing cacao seedlings to leaf litter from healthy conspecific adults enriched the seedling microbiome with Colletotrichum tropicale , a fungal endophyte known to enhance pathogen resistance of cacao seedlings by upregulating host defensive pathways. As a result, seedlings exposed to healthy conspecific litter experienced reduced pathogen damage. Our results link processes that affect the assembly and composition of microbiome communities to their functional consequences for host success, and have broad implications for understanding plant-microbe interactions. Deliberate manipulation of the plant-fungal microbiome also has potentially important applications for cacao production and other agricultural systems in general. © 2017 The Author(s).

The influence of leaf morphology on litter flammability and its utility for interpreting palaeofire.

PubMed

Belcher, Claire M

2016-06-05

Studies of palaeofire rely on quantifying the abundance of fossil charcoals in sediments to estimate changes in fire activity. However, gaining an understanding of the behaviour of palaeofires is also essential if we are to determine the palaeoecological impact of wildfires. Here, I use experimental approaches to explore relationships between litter fire behaviour and leaf traits that are observable in the fossil record. Fire calorimetry was used to assess the flammability of 15 species of conifer litter and indicated that leaf morphology related to litter bulk density and fuel load that determined the duration of burning and the total energy released. These data were applied to a fossil case study that couples estimates of palaeolitter fire behaviour to charcoal-based estimates of fire activity and observations of palaeoecological changes. The case study reveals that significant changes in fire activity and behaviour likely fed back to determine ecosystem composition. This work highlights that we can recognize and measure plant traits in the fossil record that relate to fire behaviour and therefore that further research is warranted towards estimating palaeofire behaviour as it can enhance our ability to interpret the palaeoecological impact of palaeofires throughout Earth's long evolutionary history.This article is part of the themed issue 'The interaction of fire and mankind'. © 2016 The Author(s).

Biomass is the main driver of changes in ecosystem process rates during tropical forest succession.

PubMed

Lohbeck, Madelon; Poorter, Lourens; Martínez-Ramos, Miguel; Bongers, Frans

2015-05-01

Over half of the world's forests are disturbed, and the rate at which ecosystem processes recover after disturbance is important for the services these forests can provide. We analyze the drivers' underlying changes in rates of key ecosystem processes (biomass productivity, litter productivity, actual litter decomposition, and potential litter decomposition) during secondary succession after shifting cultivation in wet tropical forest of Mexico. We test the importance of three alternative drivers of ecosystem processes: vegetation biomass (vegetation quantity hypothesis), community-weighted trait mean (mass ratio hypothesis), and functional diversity (niche complementarity hypothesis) using structural equation modeling. This allows us to infer the relative importance of different mechanisms underlying ecosystem process recovery. Ecosystem process rates changed during succession, and the strongest driver was aboveground biomass for each of the processes. Productivity of aboveground stem biomass and leaf litter as well as actual litter decomposition increased with initial standing vegetation biomass, whereas potential litter decomposition decreased with standing biomass. Additionally, biomass productivity was positively affected by community-weighted mean of specific leaf area, and potential decomposition was positively affected by functional divergence, and negatively by community-weighted mean of leaf dry matter content. Our empirical results show that functional diversity and community-weighted means are of secondary importance for explaining changes in ecosystem process rates during tropical forest succession. Instead, simply, the amount of vegetation in a site is the major driver of changes, perhaps because there is a steep biomass buildup during succession that overrides more subtle effects of community functional properties on ecosystem processes. We recommend future studies in the field of biodiversity and ecosystem functioning to separate the effects of vegetation quality (community-weighted mean trait values and functional diversity) from those of vegetation quantity (biomass) on ecosystem processes and services.

Restoration of Tidal Flow to Impounded Salt Marsh Exerts Mixed Effect on Leaf Litter Decomposition

NASA Astrophysics Data System (ADS)

Henry, B. A.; Schade, J. D.; Foreman, K.

2015-12-01

Salt marsh impoundments (e.g. roads, levees) disconnect marshes from ocean tides, which impairs ecosystem services and often promotes invasive species. Numerous restoration projects now focus on removing impoundments. Leaf litter decomposition is a central process in salt marsh carbon and nutrient cycles, and this study investigated the extent to which marsh restoration alters litter decomposition rates. We considered three environmental factors that can potentially change during restoration: salinity, tidal regime, and dominant plant species. A one-month field experiment (Cape Cod, MA) measured decay of litter bags in impounded, restored, and natural marshes under ambient conditions. A two-week lab experiment measured litter decay in controlled incubations under experimental treatments for salinity (1ppt and 30 ppt), tidal regime (inundated and 12 hr wet-dry cycles), and plant species (native Spartina alterniflora and invasive Phragmites australis). S. alterniflora decomposed faster in situ than P. australis (14±1.0% mass loss versus 0.74±0.69%). Corroborating this difference in decomposition, S. alterniflora supported greater microbial respiration during lab incubation, measured as CO2 flux from leaf litter and biological oxygen demand of water containing leached organic matter (OM). However, nutrient analysis of plant tissue and leached OM show P. australis released more nitrogen than S. alterniflora. Low salinity treatments in both lab and field experiments decayed more rapidly than high salinity treatments, suggesting that salinity inhibited microbial activity. Manipulation of inundation regime did not affect decomposition. These findings suggest the reintroduction of tidal flow to an impounded salt marsh can have mixed effects; recolonization by the native cordgrass could supply labile OM to sediment and slow carbon sequestration, while an increase in salinity might inhibit decomposition and accelerate sequestration.

Characterization of forest litter horizons through full-wave inversion of ground-penetrating radar data

NASA Astrophysics Data System (ADS)

André, Frédéric; Jonard, Mathieu; Jonard, François; Lambot, Sébastien

2015-04-01

Decomposing litter accumulated at the soil surface in forest ecosystems play a major role in a series of ecosystem processes (soil carbon sequestration, nutrient release through decomposition, water retention, buffering of soil temperature variations, tree regeneration, population dynamics of ground vegetation and soil fauna, ...). Besides, the presence of litter is acknowledged to influence remote sensing radar data over forested areas and accurate quantification of litter radiative properties is essential for proper processing of these data. In these respects, ground-penetrating radar (GPR) presents particular interests, potentially allowing for fast and non-invasive characterization of organic layers with fine spatial and/or temporal resolutions as well as for providing detailed information on litter electrical properties which are required for modeling either active or passive microwave remote sensing data. We designed an experiment in order to analyze the backscattering from forest litter horizons and to investigate the potentialities of GPR for retrieving the physical properties of these horizons. For that purpose, we used an ultrawide band radar system connected to a transmitting and receiving horn antenna. The GPR data were processed resorting to full-wave inversion of the signal, through which antenna effects are accounted for. In a first step, GPR data were acquired over artificially reconstructed layers of three different beech litter types (i.e., (i) recently fallen litter with easily discernible plant organs (OL layer), (ii) fragmented litter in partial decomposition without entire plant organs (OF layer) and (iii) combination of OL and OF litter layers) and considering in each case a range of layer thicknesses. In a second step, so as to validate the adopted methodology in real natural conditions, GPR measurements were performed in situ along a transect crossing a wide range of litter properties in terms of thickness and composition through stands of various tree species. Results from the controlled experiment demonstrated the ability of GPR to reconstruct litter horizons, showing close correspondence between inversely estimated and measured litter layer thicknesses and providing reliable estimates of litter electromagnetic properties. This experiment also highlighted the necessity of considering scattering and dielectric losses occurring within litter for proper modeling of the GPR signal, which was accounted for through frequency dependence of an effective electrical conductivity of the litter. Similar findings emerged from the in situ experiment, though somewhat lower agreement was observed between estimated and reference layer thickness values. These results show great promise for the use of GPR for non-invasive characterization of forest litter. Index Terms: Ground-penetrating radar (GPR), forest litter, frequency dependence, scattering Reference: André F., Jonard M., Lambot S., 2015. Non-invasive forest litter characterization using full-wave inversion of microwave radar data, IEEE Transactions on Geoscience and Remote Sensing, 53(2), 828-840.

Photodegradation alleviates the lignin bottleneck for carbon turnover in terrestrial ecosystems

PubMed Central

Austin, Amy T.; Méndez, M. Soledad; Ballaré, Carlos L.

2016-01-01

A mechanistic understanding of the controls on carbon storage and losses is essential for our capacity to predict and mitigate human impacts on the global carbon cycle. Plant litter decomposition is an important first step for carbon and nutrient turnover, and litter inputs and losses are essential in determining soil organic matter pools and the carbon balance in terrestrial ecosystems. Photodegradation, the photochemical mineralization of organic matter, has been recently identified as a mechanism for previously unexplained high rates of litter mass loss in arid lands; however, the global significance of this process as a control on carbon cycling in terrestrial ecosystems is not known. Here we show that, across a wide range of plant species, photodegradation enhanced subsequent biotic degradation of leaf litter. Moreover, we demonstrate that the mechanism for this enhancement involves increased accessibility to plant litter carbohydrates for microbial enzymes. Photodegradation of plant litter, driven by UV radiation, and especially visible (blue–green) light, reduced the structural and chemical bottleneck imposed by lignin in secondary cell walls. In leaf litter from woody species, specific interactions with UV radiation obscured facilitative effects of solar radiation on biotic decomposition. The generalized effect of sunlight exposure on subsequent microbial activity, mediated by increased accessibility to cell wall polysaccharides, suggests that photodegradation is quantitatively important in determining rates of mass loss, nutrient release, and the carbon balance in a broad range of terrestrial ecosystems. PMID:27044070

Vertical leaf area distribution, light transmittance, and application of the Beer-Lambert Law in four mature hardwood stands in the southern Appalachians

Treesearch

James M. Vose; Neal H. Sullivan; Barton D. Clinton; Paul V. Bolstad

1995-01-01

We quantified stand leaf area index and vertical leaf area distribution, and developed canopy extinction coefficients (k), in four mature hardwood stands. Leaf area index, calculated from litter fall and specific leaf area (cm²·g-1), ranged from 4.3 to 5.4 m²·m-2. In three of the four stands, leaf area was distributed in...

Flood pattern and weather determine Populus leaf litter breakdown and nitrogen dynamics on a cold desert floodplain

USGS Publications Warehouse

Andersen, D.C.; Nelson, S.M.

2006-01-01

Patterns and processes involved in litter breakdown on desert river floodplains are not well understood. We used leafpacks containing Fremont cottonwood (Populus deltoides subsp. wislizenii) leaf litter to investigate the roles of weather and microclimate, flooding (immersion), and macroinvertebrates on litter organic matter (OM) and nitrogen (N) loss on a floodplain in a cool-temperate semi-arid environment (Yampa River, northwestern Colorado, USA). Total mass of N in fresh autumn litter fell by ∼20% over winter and spring, but in most cases there was no further N loss prior to termination of the study after 653 days exposure, including up to 20 days immersion during the spring flood pulse. Final OM mass was 10–40% of initial values. The pattern of OM and N losses suggested most N would be released outside the flood season, when retention within the floodplain would be likely. The exclusion of macroinvertebrates modestly reduced the rate of OM loss (by about 10%) but had no effect on N dynamics over nine months. Immersion in floodwater accelerated OM loss, but modest variation in litter quality did not affect the breakdown rate. These results are consistent with the concept that decomposition on desert floodplains progresses much as does litter processing in desert uplands, but with periodic bouts of processing typical of aquatic environments when litter is inundated by floodwaters. The strong dependence of litter breakdown rate on weather and floods means that climate change or river flow management can easily disrupt floodplain nutrient dynamics.

Chronic Nitrogen Deposition Influences the Chemical Dynamics of Leaf Litter and Fine Roots During Decomposition

EPA Science Inventory

Atmospheric nitrogen deposition induces a forest carbon sink across broad parts of the Northern Hemisphere; this carbon sink may partly result from slower litter decomposition. Although microbial responses to experimental nitrogen deposition have been well-studied, evidence linki...

Sewage sludge effects on mesofauna and cork oak (Quercus suber L.) leaves decomposition in a Mediterranean forest firebreak.

PubMed

Pernin, Céline; Cortet, Jérôme; Joffre, Richard; Le Petit, Jean; Torre, Franck

2006-01-01

Effects of sewage sludge on litter mesofauna communities (Collembola and Acari) and cork oak (Quercus suber L.) leaf litter decomposition have been studied during 18 mo using litterbags in an in situ experimental forest firebreak in southeastern France. The sludge (2.74 t DM ha(-1) yr(-1)) was applied to fertilize and maintain a pasture created on the firebreak. Litterbag colonization had similar dynamics on both the control and fertilized plots and followed a typical Mediterranean pattern showing a greater abundance in spring and autumn and a lower abundance in summer. After 9 mo of litter colonization, Collembola and Acari, but mainly Oribatida, were more abundant on the sludge-fertilized plot. Leaf litter decomposition showed a similar pattern on both plots, but it was faster on the control plot. Furthermore, leaves from the fertilized plot were characterized by greater nitrogen content. Both chemical composition of leaves and sludges and the decomposition state of leaves have significantly affected the mesofauna community composition from each plot.

The effects of high-tannin leaf litter from transgenic poplars on microbial communities in microcosm soils.

PubMed

Winder, Richard S; Lamarche, Josyanne; Constabel, C Peter; Hamelin, Richard C

2013-01-01

The impacts of leaf litter from genetically modified hybrid poplar accumulating high levels of condensed tannins (proanthocyanidins) were examined in soil microcosms consisting of moss growing on sieved soil. Moss preferentially proliferated in microcosms with lower tannin content; DGGE (denaturing gradient gel electrophoresis) detected increased fungal diversity in microcosms with low-tannin litter. The proportion of cloned rDNA sequences from Actinobacteria decreased with litter addition while Bacteroidetes, Chloroflexi, Cyanobacteria, and α-Proteobacteria significantly increased. β-Proteobacteria were proportionally more numerous at high-tannin levels. Tannins had no significant impact on overall diversity of bacterial communities analyzed with various estimators. There was an increased proportion of N-fixing bacteria corresponding to the addition of litter with low-tannin levels. The addition of litter increased the proportion of Ascomycota/Basidiomycota. Dothideomycetes, Pucciniomycetes, and Tremellomycetes also increased and Agaricomycetes decreased. Agaricomycetes and Sordariomycetes were significantly more abundant in controls, whereas Pucciniomycetes increased in soil with litter from transformed trees (P = 0.051). Richness estimators and diversity indices revealed no significant difference in the composition of fungal communities; PCoA (principal coordinate analyses) partitioned the fungal communities into three groups: (i) those with higher amounts of added tannin from both transformed and untransformed treatments, (ii) those corresponding to soils without litter, and (iii) those corresponding to microcosms with litter added from trees transformed only with a β-glucuronidase control vector. While the litter from transformed poplars had significant effects on soil microbe communities, the observed impacts reflected known impacts on soil processes associated with tannins, and were similar to changes that would be expected from natural variation in tannin levels.

Survival, dispersal, and potential soil-mediated suppression of Phytophthora ramorum in a California redwood-tanoak forest.

PubMed

Fichtner, E J; Lynch, S C; Rizzo, D M

2009-05-01

Because the role of soil inoculum of Phytophthora ramorum in the sudden oak death disease cycle is not well understood, this work addresses survival, chlamydospore production, pathogen suppression, and splash dispersal of the pathogen in infested forest soils. Colonized rhododendron and bay laurel leaf disks were placed in mesh sachets before transfer to the field in January 2005 and 2006. Sachets were placed under tanoak, bay laurel, and redwood at three vertical locations: leaf litter surface, litter-soil interface, and below the soil surface. Sachets were retrieved after 4, 8, 20, and 49 weeks. Pathogen survival was higher in rhododendron leaf tissue than in bay tissue, with >80% survival observed in rhododendron tissue after 49 weeks in the field. Chlamydospore production was determined by clearing infected tissue in KOH. Moist redwood-associated soils suppressed chlamydospore production. Rain events splashed inoculum as high as 30 cm from the soil surface, inciting aerial infection of bay laurel and tanoak. Leaf litter may provide an incomplete barrier to splash dispersal. This 2-year study illustrates annual P. ramorum survival in soil and the suppressive nature of redwood-associated soils to chlamydospore production. Infested soil may serve as primary inoculum for foliar infections by splash dispersal during rain events.

Changes in the quality of chromophoric dissolved organic matter leached from senescent leaf litter during the early decomposition.

PubMed

Nishimura, Satoshi; Maie, Nagamitsu; Baba, Mitsuhisa; Sudo, Takahiro; Sugiura, Toshihiro; Shima, Eikichi

2012-01-01

Chromophoric dissolved organic matter (CDOM) leached from leaf litter is a major source of humus in mineral soil of forest ecosystems. While their functions and refractoriness depend on the physicochemical structure, there is little information on the quality of CDOM, especially for that leached in the very early stages of litter decomposition when a large amount of dissolved organic matter (DOM) is leached. This study aimed to better understand the variations/changes in the composition of CDOM leached from senescent leaf litter from two tree species during the early stage of decomposition. Leaf litter from a conifer tree (Japanese cedar, D. Don) and a deciduous broad-leaved tree (Konara oak, Thunb.) were incubated in columns using simulated rainfall events periodically for a total of 300 d at 20°C. The quality of CDOM was investigated based on the fluorescence properties by using a combination of excitation-emission matrix fluorescence (EEM) and parallel factor analysis (PARAFAC). In addition, the phenolic composition of DOM was investigated at a molecular level by thermally assisted hydrolysis and methylation-gas chromatography-mass spectrometry (THM-GC-MS) in the presence of tetramethylammonium hydroxide (TMAH). The EEM was statistically decomposed into eight fluorescence components (two tannin/peptide-like peaks, one protein-like peak, and five humic-like peaks). A significant contribution of tannin/peptide-like peaks was observed at the beginning of incubation, but these peaks decreased quickly and humic-like peaks increased within 1 mo of incubation. The composition of humic-like peaks was different between tree species and changed over the incubation period. Since tannin-derived phenolic compounds were detected in the DOM collected after 254 d of incubation on THM-GC-MS, it was suggested that tannins partially changed its structure, forming various humic-like peaks during the early decomposition. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Soil coverage reduce photodegradation and promotes the development of soil-microbial films on dryland leaf litter

USDA-ARS?s Scientific Manuscript database

Litter decomposition is a central focus of ecosystem science because of its importance to biogeochemical pools and cycling, but predicting dryland decomposition dynamics is problematic. Some studies indicate photodegradation by ultraviolet (UV) radiation can be a significant driver of dryland decomp...

Leaf Litter Decomposition and Nutrient Dynamics in Four Southern Forested Floodplain Communities

Treesearch

Terrell T. Baker; B. Graeme Lockaby; William H. Conner; Calvin E. Meier; John A. Stanturf

2001-01-01

Decomposition of site-specific litter mixtures was monitored for 100 wk in four Roodplaht communities: (i) a mixed oak community along the Cache River in central Arkansas, (ii) a sweetgum (Liquidambar styraciflua L.)-cherrybark oak (Quercus falcata var. pagodaefolia Ell.) community along Iatt Creek in...

Fungal succession in relation to volatile organic compounds emissions from Scots pine and Norway spruce leaf litter-decomposing fungi

NASA Astrophysics Data System (ADS)

Isidorov, Valery; Tyszkiewicz, Zofia; Pirożnikow, Ewa

2016-04-01

Leaf litter fungi are partly responsible for decomposition of dead material, nutrient mobilization and gas fluxes in forest ecosystems. It can be assumed that microbial destruction of dead plant materials is an important source of volatile organic compounds (VOCs) emitted into the atmosphere from terrestrial ecosystems. However, little information is available on both the composition of fungal VOCs and their producers whose community can be changed at different stages of litter decomposition. The fungal community succession was investigated in a litter bag experiment with Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) needle litter. The succession process can be divided into a several stages controlled mostly by changes in litter quality. At the very first stages of decomposition the needle litter was colonized by ascomycetes which can use readily available carbohydrates. At the later stages, the predominance of Trichoderma sp., the known producers of cellulolytic enzymes, was documented. To investigate the fungi-derived VOCs, eight fungi species were isolated. As a result of gas chromatographic analyses, as many as 75C2sbnd C15 fungal volatile compounds were identified. Most components detected in emissions were very reactive substances: the principal groups of VOCs were formed by monoterpenes, carbonyl compounds and aliphatic alcohols. It was found that production of VOCs by fungi is species specific: only 10 metabolites were emitted into the gas phase by all eight species. The reported data confirm that the leave litter decomposition is important source of reactive organic compounds under the forest canopy.

Comparison of the chemical alteration trajectory of Liriodendron tulipifera L. leaf litter among forests with different earthworm abundance

NASA Astrophysics Data System (ADS)

Filley, Timothy R.; McCormick, Melissa K.; Crow, Susan E.; Szlavecz, Katalin; Whigham, Dennis F.; Johnston, Cliff T.; van den Heuvel, Ronald N.

2008-03-01

To investigate the control of earthworm populations on leaf litter biopolymer decay dynamics, we analyzed the residues of Liriodendron tulipifera L. (tulip poplar) leaves after six months of decay, comparing open surface litter and litter bag experiments among forests with different native and invasive earthworm abundances. Six plots were established in successional tulip poplar forests where sites varied in earthworm density and biomass, roughly 4-10 fold, of nonnative lumbricid species. Analysis of residues by diffuse reflectance Fourier transform infrared spectroscopy and alkaline CuO extraction indicated that open decay in sites with abundant earthworms resulted in residues depleted in cuticular aliphatic and polysaccharide components and enriched in ether-linked lignin relative to open decay in low earthworm abundance plots. Decay within earthworm-excluding litter bags resulted in an increase in aliphatic components relative to initial amendment and similar chemical trajectory to low earthworm open decay experiments. All litter exhibited a decline in cinnamyl-based lignin and an increase in nitrogen content. The influence of earthworm density on the chemical trajectory of litter decay was primarily a manifestation of the physical separation and concentration of lignin-rich and cutin-poor petioles with additional changes promoted by either microorganisms and/or mesofauna resulting in nitrogen addition and polysaccharide loss. These results illustrate how projected increases in invasive earthworm activity in northern North American forests could alter the chemical composition of organic matter in litter residues and potentially organic matter reaching the soil which may result in shifts in the aromatic and aliphatic composition of soils in different systems.

Plant, fungal, bacterial, and nitrogen interactions in the litter layer of a native Patagonian forest.

PubMed

Vivanco, Lucía; Rascovan, Nicolás; Austin, Amy T

2018-01-01

Plant-microbial interactions in the litter layer represent one of the most relevant interactions for biogeochemical cycling as litter decomposition is a key first step in carbon and nitrogen turnover. However, our understanding of these interactions in the litter layer remains elusive. In an old-growth mixed Nothofagus forest in Patagonia, we studied the effects of single tree species identity and the mixture of three tree species on the fungal and bacterial composition in the litter layer. We also evaluated the effects of nitrogen (N) addition on these plant-microbial interactions. In addition, we compared the magnitude of stimulation of litter decomposition due to home field advantage (HFA, decomposition occurs more rapidly when litter is placed beneath the plant species from which it had been derived than beneath a different plant species) and N addition that we previously demonstrated in this same forest, and used microbial information to interpret these results. Tree species identity had a strong and significant effect on the composition of fungal communities but not on the bacterial community of the litter layer. The microbial composition of the litter layer under the tree species mixture show an averaged contribution of each single tree species. N addition did not erase the plant species footprint on the fungal community, and neither altered the bacterial community. N addition stimulated litter decomposition as much as HFA for certain tree species, but the mechanisms behind N and HFA stimulation may have differed. Our results suggest that stimulation of decomposition from N addition might have occurred due to increased microbial activity without large changes in microbial community composition, while HFA may have resulted principally from plant species' effects on the litter fungal community. Together, our results suggest that plant-microbial interactions can be an unconsidered driver of litter decomposition in temperate forests.

Effects of road deicer (NaCl) and amphibian grazers on detritus processing in pond mesocosms.

PubMed

Van Meter, Robin J; Swan, Christopher M; Trossen, Carrie A

2012-10-01

Road deicers have been identified as potential stressors in aquatic habitats throughout the United States, but we know little regarding associated impacts to ecosystem function. A critical component of ecosystem function that has not previously been evaluated with respect to freshwater salinization is the impact on organic matter breakdown. The purpose of this study was to evaluate cumulative effects of road deicers and tadpole grazers on leaf litter breakdown rate (g d(-1) ) and microbial respiration (mg O(2)  g leaf(-1) h(-1) ). To test this interaction, in May 2008 the authors added dry leaf litter (Quercus spp.) to forty 600-L pond mesocosms and inoculated each with algae and zooplankton. In a full-factorial design, they manipulated a realistic level of road salt (ambient or elevated at 645 mg L(-1) Cl(-) ) and tadpole (Hyla versicolor) presence or absence. The elevated chloride treatment reduced microbial respiration by 24% in the presence of tadpoles. The breakdown of leaf litter by tadpoles occurred 9.7% faster under ambient chloride conditions relative to the elevated chloride treatment. Results of the present study suggest that the microbial community is directly impacted by road deicers and heavy tadpole grazing under ambient conditions limits microbial capacity to process detritus. Road salts and tadpoles interact to limit microbial respiration, but to a lesser extent leaf mass loss rate, thereby potentially restricting energy flow from detrital sources in pond ecosystems. Copyright © 2012 SETAC.

The Influence of Leaf Fall and Organic Carbon Availability on Nitrogen Cycling in a Headwater Stream

NASA Astrophysics Data System (ADS)

Thomas, S. A.; Kristin, A.; Doyle, B.; Goodale, C. L.; Gurwick, N. P.; Lepak, J.; Kulkari, M.; McIntyre, P.; McCalley, C.; Raciti, S.; Simkin, S.; Warren, D.; Weiss, M.

2005-05-01

The study of allochthonous carbon has a long and distinguished history in stream ecology. Despite this legacy, relatively little is known regarding the influence of leaf litter on nutrient dynamics. We conducted 15N-NO3 tracer additions to a headwater stream in upstate New York before and after autumn leaf fall to assess the influence of leaf litter on nitrogen spiraling. In addition, we amended the stream with labile dissolved organic carbon (as acetate) midway through each experiment to examine whether organic carbon availability differentially stimulated nitrogen cycling. Leaf standing stocks increased from 53 to 175 g dry mass m-2 and discharge more than tripled (6 to 20 L s-1) between the pre- and post-leaf fall period. In contrast, nitrate concentration fell from approximately 50 to less then 10 ug L-1. Despite higher discharge, uptake length was shorter following leaf fall under both ambient (250 and 72 m, respectively) and DOC amended (125 and 45 m) conditions. Uptake velocity increased dramatically following leaf fall, despite a slight decline in the areal uptake rate. Dissolved N2 gas samples were also collected to estimate denitrification rates under each experimental condition. The temporal extent of increased nitrogen retention will also be explored.

Sorption of polyphenolics (tannins) to natural soils

USDA-ARS?s Scientific Manuscript database

Tannins enter soil systems via rainfall through the leaf canopy, leaf litter decomposition, and root exudation and decomposition. For tannins released into soils, the relative importance of sorption to soil; chemical reactions with soil minerals; and biological decomposition is unknown. Determinin...

Field and lab conditions alter microbial enzyme and biomass dynamics driving decomposition of the same leaf litter

PubMed Central

Rinkes, Zachary L.; Sinsabaugh, Robert L.; Moorhead, Daryl L.; Grandy, A. Stuart; Weintraub, Michael N.

2013-01-01

Fluctuations in climate and edaphic factors influence field decomposition rates and preclude a complete understanding of how microbial communities respond to plant litter quality. In contrast, laboratory microcosms isolate the intrinsic effects of litter chemistry and microbial community from extrinsic effects of environmental variation. Used together, these paired approaches provide mechanistic insights to decomposition processes. In order to elucidate the microbial mechanisms underlying how environmental conditions alter the trajectory of decay, we characterized microbial biomass, respiration, enzyme activities, and nutrient dynamics during early (<10% mass loss), mid- (10–40% mass loss), and late (>40% mass loss) decay in parallel field and laboratory litter bag incubations for deciduous tree litters with varying recalcitrance (dogwood < maple < maple-oak mixture < oak). In the field, mass loss was minimal (<10%) over the first 50 days (January–February), even for labile litter types, despite above-freezing soil temperatures and adequate moisture during these winter months. In contrast, microcosms displayed high C mineralization rates in the first week. During mid-decay, the labile dogwood and maple litters in the field had higher mass loss per unit enzyme activity than the lab, possibly due to leaching of soluble compounds. Microbial biomass to litter mass (B:C) ratios peaked in the field during late decay, but B:C ratios declined between mid- and late decay in the lab. Thus, microbial biomass did not have a consistent relationship with litter quality between studies. Higher oxidative enzyme activities in oak litters in the field, and higher nitrogen (N) accumulation in the lab microcosms occurred in late decay. We speculate that elevated N suppressed fungal activity and/or biomass in microcosms. Our results suggest that differences in microbial biomass and enzyme dynamics alter the decay trajectory of the same leaf litter under field and lab conditions. PMID:24027563

Temperature and substrate chemistry as major drivers of interregional variability of leaf microbial decomposition and cellulolytic activity in headwater streams.

PubMed

Fenoy, Encarnación; Casas, J Jesús; Díaz-López, Manuel; Rubio, Juan; Guil-Guerrero, J Luís; Moyano-López, Francisco J

2016-11-01

Abiotic factors, substrate chemistry and decomposers community composition are primary drivers of leaf litter decomposition. In soil, much of the variation in litter decomposition is explained by climate and substrate chemistry, but with a significant contribution of the specialisation of decomposer communities to degrade specific substrates (home-field advantage, HFA). In streams, however, HFA effects on litter decomposition have not been explicitly tested. We evaluated responses of microbial decomposition and β-glucosidase activity to abiotic factors, substrate and decomposer assemblages, using a reciprocal litter transplant experiment: 'ecosystem type' (mountain vs lowland streams) × 'litter chemistry' (alder vs reed). Temperature, pH and ionic concentration were higher in lowland streams. Decomposition for both species was faster in lowland streams. Decomposition of reed was more accelerated in lowland compared with mountain streams than that of alder, suggesting higher temperature sensitivity of decomposition in reed. Q10 (5°C-15°C) values of β-glucosidase activity were over 2. The alkaline pH and high ionic concentration of lowland streams depleted enzyme activity. We found similar relationships of decomposition or enzyme activity with abiotic factors for both species, suggesting limited support to the HFA hypothesis. Overall, our results suggest a prime role of temperature interacting with substrate chemistry on litter decomposition. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Saltcedar (Tamarix ramosissima) invasion alters organic matter dynamics in a desert stream

USGS Publications Warehouse

Kennedy, T.A.; Hobbie, S.E.

2004-01-01

1. We investigated the impacts of saltcedar invasion on organic matter dynamics in a spring-fed stream (Jackrabbit Spring) in the Mojave Desert of southern Nevada, U.S.A., by experimentally manipulating saltcedar abundance. 2. Saltcedar heavily shaded Jackrabbit Spring and shifted the dominant organic matter inputs from autochthonous production that was available throughout the year to allochthonous saltcedar leaf litter that was strongly pulsed in the autumn. Specifically, reaches dominated by saltcedar had allochthonous litter inputs of 299 g ash free dry mass (AFDM) m-2 year-1, macrophyte production of 15 g AFDM m-2 year-1 and algal production of 400 g AFDM m-2 year-1, while reaches dominated by native riparian vegetation or where saltcedar had been experimentally removed had allochthonous litter inputs of 7-34 g AFDM m -2 year-1, macrophyte production of 118-425 g AFDM m -2 year-1 and algal production of 640-900 g AFDM m -2 year-1. 3. A leaf litter breakdown study indicated that saltcedar also altered decomposition in Jackrabbit Spring, mainly through its influence on litter quality rather than by altering the environment for decomposition. Decomposition rates for saltcedar were lower than for ash (Fraxinus velutina), the dominant native allochthonous litter type, but faster than for bulrush (Scirpus americanus), the dominant macrophyte in this system.

Species identities, not functional groups, explain the effects of earthworms on litter carbon-derived soil respiration

USDA-ARS?s Scientific Manuscript database

Soil respiration is frequently measured as a surrogate for biological activities and is important in soil carbon cycling. The heterotrophic component of soil respiration is primarily driven by microbial decomposition of leaf litter and soil organic matter, and is partially controlled by resource ava...

Leaf litter decomposition and macroinvertebrate communities in headwater streams draining pine and hardwood catchments

Treesearch

Matt R. Whiles; J. Bruce Wallace

1997-01-01

Benthic invertebrates, litter decomposition, and litterbag invertebrates were examined in streams draining pine monoculture and undisturbed hardwood catchments at the Coweeta Hydrologic Laboratory in the southern Appalachian Mountains, USA. Bimonthly benthic samples were collected from a stream draining a pine catchment at Coweeta during 1992, and compared to...

Climate history shapes contemporary leaf litter decomposition

Treesearch

Michael S. Strickland; Ashley D. Keiser; Mark A. Bradford

2015-01-01

Litter decomposition is mediated by multiple variables, of which climate is expected to be a dominant factor at global scales. However, like other organisms, traits of decomposers and their communities are shaped not just by the contemporary climate but also their climate history. Whether or not this affects decomposition rates is underexplored. Here we source...

Global synthesis of the temperature sensitivity of leaf litter breakdown in streams and rivers

DOE PAGES

Follstad Shah, Jennifer J.; Kominoski, John S.; Ardón, Marcelo; ...

2017-02-28

Streams and rivers are important conduits of terrestrially derived carbon (C) to atmospheric and marine reservoirs. Leaf litter breakdown rates are expected to increase as water temperatures rise in response to climate change. The magnitude of increase in breakdown rates is uncertain, given differences in litter quality and microbial and detritivore community responses to temperature, factors that can influence the apparent temperature sensitivity of breakdown and the relative proportion of C lost to the atmosphere vs. stored or transported downstream. We synthesized 1025 records of litter breakdown in streams and rivers to quantify its temperature sensitivity, as measured by themore » activation energy (Ea, in eV). Temperature sensitivity of litter breakdown varied among twelve plant genera for which Ea could be calculated. Higher values of Ea were correlated with lower-quality litter, but these correlations were influenced by a single, N-fixing genus (Alnus). Ea values converged when genera were classified into three breakdown rate categories, potentially due to continual water availability in streams and rivers modulating the influence of leaf chemistry on breakdown. Across all data representing 85 plant genera, the Ea was 0.34 ± 0.04 eV, or approximately half the value (0.65 eV) predicted by metabolic theory. Our results indicate that average breakdown rates may increase by 5–21% with a 1–4 °C rise in water temperature, rather than a 10–45% increase expected, according to metabolic theory. Differential warming of tropical and temperate biomes could result in a similar proportional increase in breakdown rates, despite variation in Ea values for these regions (0.75 ± 0.13 eV and 0.27 ± 0.05 eV, respectively). The relative proportions of gaseous C loss and organic matter transport downstream should not change with rising temperature given that Ea values for breakdown mediated by microbes alone and microbes plus detritivores were similar at the global scale.« less

Global synthesis of the temperature sensitivity of leaf litter breakdown in streams and rivers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Follstad Shah, Jennifer J.; Kominoski, John S.; Ardón, Marcelo

Streams and rivers are important conduits of terrestrially derived carbon (C) to atmospheric and marine reservoirs. Leaf litter breakdown rates are expected to increase as water temperatures rise in response to climate change. The magnitude of increase in breakdown rates is uncertain, given differences in litter quality and microbial and detritivore community responses to temperature, factors that can influence the apparent temperature sensitivity of breakdown and the relative proportion of C lost to the atmosphere vs. stored or transported downstream. We synthesized 1025 records of litter breakdown in streams and rivers to quantify its temperature sensitivity, as measured by themore » activation energy (Ea, in eV). Temperature sensitivity of litter breakdown varied among twelve plant genera for which Ea could be calculated. Higher values of Ea were correlated with lower-quality litter, but these correlations were influenced by a single, N-fixing genus (Alnus). Ea values converged when genera were classified into three breakdown rate categories, potentially due to continual water availability in streams and rivers modulating the influence of leaf chemistry on breakdown. Across all data representing 85 plant genera, the Ea was 0.34 ± 0.04 eV, or approximately half the value (0.65 eV) predicted by metabolic theory. Our results indicate that average breakdown rates may increase by 5–21% with a 1–4 °C rise in water temperature, rather than a 10–45% increase expected, according to metabolic theory. Differential warming of tropical and temperate biomes could result in a similar proportional increase in breakdown rates, despite variation in Ea values for these regions (0.75 ± 0.13 eV and 0.27 ± 0.05 eV, respectively). The relative proportions of gaseous C loss and organic matter transport downstream should not change with rising temperature given that Ea values for breakdown mediated by microbes alone and microbes plus detritivores were similar at the global scale.« less

Nutrient dynamics and decomposition of riparian Arundinaria gigantea (Walt.)Muhl. leaves in southern Illinois

USDA-ARS?s Scientific Manuscript database

Leaf litter quality and quantity can influence soil nutrient dynamics and stream productivity through decomposition and serving as allochthonous stream inputs. Leaf deposition, nitrogen (N)-resorption efficiency and proficiency, and decomposition rates were analyzed in riparian stands of Arundinaria...

Effects of multiple but low pesticide loads on aquatic fungal communities colonizing leaf litter.

PubMed

Talk, Anne; Kublik, Susanne; Uksa, Marie; Engel, Marion; Berghahn, Rüdiger; Welzl, Gerhard; Schloter, Michael; Mohr, Silvia

2016-08-01

In the first tier risk assessment (RA) of pesticides, risk for aquatic communities is estimated by using results from standard laboratory tests with algae, daphnids and fish for single pesticides such as herbicides, fungicides, and insecticides. However, fungi as key organisms for nutrient cycling in ecosystems as well as multiple pesticide applications are not considered in the RA. In this study, the effects of multiple low pesticide pulses using regulatory acceptable concentrations (RACs) on the dynamics of non-target aquatic fungi were investigated in a study using pond mesocosm. For that, fungi colonizing black alder (Alnus glutinosa) leaves were exposed to multiple, low pulses of 11 different pesticides over a period of 60days using a real farmer's pesticide application protocol for apple cropping. Four pond mesocosms served as treatments and 4 as controls. The composition of fungal communities colonizing the litter material was analyzed using a molecular fingerprinting approach based on the terminal Restriction Fragment Length Polymorphism (t-RFLP) of the fungal Internal Transcribed Spacer (ITS) region of the ribonucleic acid (RNA) gene(s). Our data indicated a clear fluctuation of fungal communities based on the degree of leaf litter degradation. However significant effects of the applied spraying sequence were not observed. Consequently also degradation rates of the litter material were not affected by the treatments. Our results indicate that the nutrient rich environment of the leaf litter material gave fungal communities the possibility to express genes that induce tolerance against the applied pesticides. Thus our data may not be transferred to other fresh water habitats with lower nutrient availability. Copyright © 2016. Published by Elsevier B.V.

Ecological and evolutionary variation in community nitrogen use traits during tropical dry forest secondary succession.

PubMed

Bhaskar, Radika; Porder, Stephen; Balvanera, Patricia; Edwards, Erika J

2016-05-01

We assessed the role of ecological and evolutionary processes in driving variation in leaf and litter traits related to nitrogen (N) use among tropical dry forest trees in old-growth and secondary stands in western Mexico. Our expectation was that legumes (Fabaceae), a dominant component of the regional flora, would have consistently high leaf N and therefore structure phylogenetic variation in N-related traits. We also expected ecological selection during succession for differences in nitrogen use strategies, and corresponding shifts in legume abundance. We used phylogenetic analyses to test for trait conservatism in foliar and litter N, C:N, and N resorption. We also evaluated differences in N-related traits between old-growth and secondary forests. We found a weak phylogenetic signal for all traits, partly explained by wide variation within legumes. Across taxa we observed a positive relationship between leaf and litter N, but no shift in resorption strategies along the successional gradient. Despite species turnover, N-resorption, and N-related traits showed little change across succession, suggesting that, at least for these traits, secondary forests rapidly recover ecosystem function. Collectively, our results also suggest that legumes should not be considered a single functional group from a biogeochemical perspective.

Effects of land-use change on community composition of tropical amphibians and reptiles in Sulawesi, Indonesia.

PubMed

Wanger, Thomas C; Iskandar, Djoko T; Motzke, Iris; Brook, Barry W; Sodhi, Navjot S; Clough, Yann; Tscharntke, Teja

2010-06-01

Little is known about the effects of anthropogenic land-use change on the amphibians and reptiles of the biodiverse tropical forests of Southeast Asia. We studied a land-use modification gradient stretching from primary forest, secondary forest, natural-shade cacao agroforest, planted-shade cacao agroforest to open areas in central Sulawesi, Indonesia. We determined species richness, abundance, turnover, and community composition in all habitat types and related these to environmental correlates, such as canopy heterogeneity and thickness of leaf litter. Amphibian species richness decreased systematically along the land-use modification gradient, but reptile richness and abundance peaked in natural-shade cacao agroforests. Species richness and abundance patterns across the disturbance gradient were best explained by canopy cover and leaf-litter thickness in amphibians and by canopy heterogeneity and cover in reptiles. Amphibians were more severely affected by forest disturbance in Sulawesi than reptiles. Heterogeneous canopy cover and thick leaf litter should be maintained in cacao plantations to facilitate the conservation value for both groups. For long-term and sustainable use of plantations, pruned shade trees should be permanently kept to allow rejuvenation of cacao and, thus, to prevent repeated forest encroachment.

Transect studies on pine litter organic matter: decomposition and chemical properties of upper soil layers in Polish forests

Treesearch

Alicja Breymeyer; Marek Degorski; David Reed

1998-01-01

The relationship between litter decomposition rate, some chemical properties of upper soil layers (iron, manganese, zinc, copper, lead, mercury, nickel, chrome in humus-mineral horizon-A), and litter (the same eight elements in needle litter fraction) in pine forests of Poland was studied. Heavy metal content in organic-mineral horizon of soils was highly correlated...

Digestive strategies in two species of leaf-eating land crabs (Brachyura: Gecarcinidae) in a rain forest.

PubMed

Greenaway, P; Raghaven, S

1998-01-01

Two species of herbivorous land crabs from Christmas Island, Cardisoma hirtipes and Gecarcoidea natalis, overlap in both diet and distribution. This study compared the dietary preferences and digestive capabilities of these two species on a diet of leaf litter to establish the digestive strategies each adopts and the likely degree of competition for food. C. hirtipes preferred green to yellow or brown leaves of Ficus macrophylla in short-term food-choice experiments. Brown leaves were least favoured. G. natalis showed no preference for the different leaf types and in the field ate chiefly brown and decomposing leaf litter. When fed green leaves, C. hirtipes had a low food intake (4.5+/-0.36 g kg-1 d-1) and a short retention time for food, and the readily digestible components of the diet constituted greater than 84% of the dry matter assimilated. When fed brown leaves, the intake was increased 3.3 times, but retention time remained short, and assimilation coefficients for all nutrients were low. The readily digestible fraction of the diet made the chief contribution to dry matter assimilation (69%), and hemicellulose (19%) and cellulose (21%) were also significantly used. This pattern of food intake and assimilation contrasts with that for G. natalis, which had a low intake of brown leaves and a longer retention time associated with higher nutrient assimilation, particularly of complex polysaccharides. It is suggested that through their feeding preferences and habits, these two sympatric species use opposite ends of the leaf litter quality spectrum on Christmas Island.

Biochemical and molecular characterization of an atypical manganese peroxidase of the litter-decomposing fungus Agrocybe praecox.

PubMed

Hildén, Kristiina; Mäkelä, Miia R; Steffen, Kari T; Hofrichter, Martin; Hatakka, Annele; Archer, David B; Lundell, Taina K

2014-11-01

Agrocybe praecox is a litter-decomposing Basidiomycota species of the order Agaricales, and is frequently found in forests and open woodlands. A. praecox grows in leaf-litter and the upper soil and is able to colonize bark mulch and wood chips. It produces extracellular manganese peroxidase (MnP) activities and mineralizes synthetic lignin. In this study, the A. praecox MnP1 isozyme was purified, cloned and enzymatically characterized. The enzyme catalysed the oxidation of Mn(2+) to Mn(3+), which is the specific reaction for manganese-dependent class II heme-peroxidases, in the presence of malonate as chelator with an activity maximum at pH 4.5; detectable activity was observed even at pH 7.0. The coding sequence of the mnp1 gene demonstrates a short-type of MnP protein with a slightly modified Mn(2+) binding site. Thus, A. praecox MnP1 may represent a novel group of atypical short-MnP enzymes. In lignocellulose-containing cultures composed of cereal bran or forest litter, transcription of mnp1 gene was followed by quantitative real-time RT-PCR. On spruce needle litter, mnp1 expression was more abundant than on leaf litter after three weeks cultivation. However, the expression was constitutive in wheat and rye bran cultures. Our data show that the atypical MnP of A. praecox is able to catalyse Mn(2+) oxidation, which suggests its involvement in lignocellulose decay by this litter-decomposer. Copyright © 2014 Elsevier Inc. All rights reserved.

Conversion of tropical lowland forest reduces nutrient return through litterfall, and alters nutrient use efficiency and seasonality of net primary production.

PubMed

Kotowska, Martyna M; Leuschner, Christoph; Triadiati, Triadiati; Hertel, Dietrich

2016-02-01

Tropical landscapes are not only rapidly transformed by ongoing land-use change, but are additionally confronted by increasing seasonal climate variation. There is an increasing demand for studies analyzing the effects and feedbacks on ecosystem functioning of large-scale conversions of tropical natural forest into intensively managed cash crop agriculture. We analyzed the seasonality of aboveground litterfall, fine root litter production, and aboveground woody biomass production (ANPP(woody)) in natural lowland forests, rubber agroforests under natural tree cover ("jungle rubber"), rubber and oil palm monocultures along a forest-to-agriculture transformation gradient in Sumatra. We hypothesized that the temporal fluctuation of litter production increases with increasing land-use intensity, while the associated nutrient fluxes and nutrient use efficiency (NUE) decrease. Indeed, the seasonal variation of aboveground litter production and ANPP(woody) increased from the natural forest to the plantations, while aboveground litterfall generally decreased. Nutrient return through aboveground litter was mostly highest in the natural forest; however, it was significantly lower only in rubber plantations. NUE of N, P and K was lowest in the oil palm plantations, with natural forest and the rubber systems showing comparably high values. Root litter production was generally lower than leaf litter production in all systems, while the root-to-leaf ratio of litter C flux increased along the land-use intensity gradient. Our results suggest that nutrient and C cycles are more directly affected by climate seasonality in species-poor agricultural systems than in species-rich forests, and therefore might be more susceptible to inter-annual climate fluctuation and climate change.

Short chain nitrocompounds as a treatment of layer hen manure and litter; effects on in vitro survivability of Salmonella, generic E. coli, and nitrogen metabolism

USDA-ARS?s Scientific Manuscript database

Layer hen manure and litter contain appreciable amounts of uric acid, which makes these good crude protein sources for ruminants. Rumen microbial populations can upgrade the nitrogen in uric acid into high quality microbial protein of nutritional value to the host. Layer hen manure and litter can ...

Predicting the Spatial Variability of Fuel Moisture Content in Mountainous Eucalyptus Forests

NASA Astrophysics Data System (ADS)

Sheridan, G. J.; Nyman, P.; Lane, P. N. J.; Metzen, D.

2014-12-01

In steep mountainous landscapes, topographic aspect can play a significant role in small-scale (ie. scales in the order of 10's ha) variability in surface fuel moisture. Experimental sites for monitoring microclimate variables and moisture content in litter and in near-surface soils were established at a control site and on four contrasting aspects (north, south, east and west) in southeast Australia. At each of the four microclimate sites sensors are arranged to measure the soil moisture (2 replicates), surface fuel moisture at 2.5cm depth (12 replicates), precipitation throughfall (3 replicates), radiation (3 replicates), and screen level relative humidity, air temperature, leaf wetness, and wind speed (1 replicate of each). Temperature and relative humidity are also measured within the dead fine surface fuel using Ibutton's (4 replicates). All measurements are logged continuously at 15 min intervals. The moisture content of the surface fuel is estimated using a novel method involving high-replication of low-cost continuous soil moisture sensors placed at the centre of a 5cm deep sample of fine dead surface fuel, referred to here as "litter-packs". The litter-packs were constructed from fuels collected from the area surrounding the microclimate site. The initial results show the moisture regime on the forest floor was highly sensitive to the incoming shortwave radiation, which was up to 6 times higher in the north-facing (equatorial) slopes due to slope orientation and the sparse vegetation compared to vegetation on the south-facing (polar facing) slopes. Differences in shortwave radiation resulted in peak temperatures within the litter that were up to 2 times higher on the equatorial-facing site than those on the polar-facing site. For instance, on a day in November 2013 with maximum open air temperature of 35o C, the temperatures within the litter layer at the north-facing and south-facing sites were 54o C and 32o C, respectively, despite air temperature at the two sites differing by less than 2o C. The minimum gravimetric water content in the litter layer on the same day was 21% on the equatorial-facing slope and 85% on the polar-facing slope. The experimental data has been used to calibrate a topographic downscaling algorithm, yielding estimates of surface fuel moisture at 20m resolution.

Changes in litter quality induced by nutrient addition alter litter decomposition in an alpine meadow on the Qinghai-Tibet Plateau

PubMed Central

Zhu, Wenyan; Wang, Jinzhou; Zhang, Zhenhua; Ren, Fei; Chen, Litong; He, Jin-Sheng

2016-01-01

The effects of nitrogen (N) and phosphorus (P) addition on litter decomposition are poorly understood in Tibetan alpine meadows. Leaf litter was collected from plots within a factorial N × P addition experiment and allowed to decompose over 708 days in an unfertilized plot to determine the effects of N and/or P addition on litter decomposition. Results showed that nutrient addition significantly affected initial P and P-related biochemical properties of litter from all four species. However, the responses of litter N and N-related biochemical properties to nutrient addition were quite species-specific. Litter C decomposition and N release were species-specific. However, N and P addition significantly affected litter P release. Ratios of Hemicellulose + Cellulose to N and P were significantly related to litter C decomposition; C:N ratio was a determinant of litter N release; and C:P and (Hemicellulose + Cellulose):P controlled litter P release. Overall, litter C decomposition was controlled by litter quality of different plant species, and strongly affected by P addition. Increasing N availability is likely to affect litter C decomposition more indirectly by shifting plant species composition than directly by improving litter quality, and may accelerate N and P cycles, but shift the ecosystem to P limitation. PMID:27694948

Community structure and estimated contribution of primary consumers (Nematodes and Copepods) of decomposing plant litter (Juncus roemerianus and Rhizophora mangle) in South Florida

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fell, J.W.; Cefalu, R.

1984-01-01

The paper discusses the meiofauna associated with decomposing leaf litter from two species of coastal marshland plants: the black needle rush, Juncus roemerianus and the red mangrove, Rhizophora mangle. The following aspects were investigated: (1) types of meiofauna present, especially nematodes; (2) changes in meiofaunal community structures with regard to season, station location, and type of plant litter; (3) amount of nematode and copepod biomass present on the decomposing plant litter; and (4) an estimation of the possible role of the nematodes in the decomposition process. 28 references, 5 figures, 9 tables. (ACR)

Effects of acidic precipitation on leaf decomposition rates, microbial biomass, and leaf pack macroinvertebrates in six streams on the Allegheny plateau of West Virginia

Treesearch

Erik S. Engstrom; Sean K. Meegan; Sue A. Perry; William B. Perry

1996-01-01

We studied the effects of acidification on leaf litter decomposition in six headwater streams in the Monongahela National Forest. These streams differed in underlying geology and mean baseflow pH (3.99, 4.24, 6.13, 6.47, 6.59, and 7.52). We placed 10-gram leaf packs of white oak, red maple, and yellow poplar in each stream, and retrieved them after two days, two weeks...

Highly Active Ice Nuclei from Tree Leaf Litters Retain Activity for Decades

NASA Astrophysics Data System (ADS)

Schnell, R. C.; Hill, T. C. J.

2015-12-01

Biogenic ice nuclei (IN) studied since the 1960s were first observed in tree leaf litters, in a few bacteria species and later in fungi and lichens. Recently, viable IN bacteria in precipitation have been used as a metric of their possible role in precipitation formation. Although bacterial IN activity is deactivated by a variety of common environmental stresses, we present data showing that IN found in a potpourri of decayed plant leaves, bacteria, molds and fungi etc. in plant litters are exceptionally stable and active over decades while in storage. As such, their atmospheric IN potential is worthy of further study due to their environmental persistence. In August 1970 litter collected in a grove of deciduous trees near Red Deer, AB, Canada was tested for IN (drop freezing technique). The sample initiated ice at -4C with 109 IN per gram of litter active at -10C. A few kilograms were stored in a plastic bag and tested every few years for IN content; the IN activity remained essentially unchanged over 40 years. In 2011, litter collected in the same grove had the same IN activity as the sample tested over the intervening 40 years. Boiling a gram sample of this litter in 100 grams of water deactivated 99 % of the IN activity down to -13C. None of 88 different bacteria cultures several of which appeared to Pseudomonads (common IN producing bacteria) from the fresh litter produced any active IN. A sample of the litter was placed on the top of a 15 cm column of laboratory grade kaolin and water dripped onto the litter. Ten days later the water reached the bottom of the column. The kaolin was dried and tested for IN. The prior essentially IN free kaolin now exhibited IN activity at -4C with 105 IN active at -10C. The litter exposed kaolin retained the IN activity for 25 years. Baking the kaolin removed the active IN. This suggests that IN activity attributed to kaolin particles sometimes seen at the nucleus of snow crystals could be of biological origin.

Nonadditive effects of leaf litter species diversity on breakdown dynamics in a deteritus-bases stream

Treesearch

J.S. Kominoski; C.M. Pringle; B.A. Ball; M.A. Bradford; D.C. Coleman; D.B. Hall; M.D. Hunter

2007-01-01

Since species loss is predicted to be nonrandom, it is important to understand the manner in which those species that we anticipate losing interact with other species to affect ecosystem function. We tested whether litter species diversity, measured as richness and composition, affects breakdown dynamics in a detritus-based stream. Using full-factorial analyses of...

Controls on fallen leaf chemistry and forest floor element masses in native and novel forests across a tropical island

Treesearch

H.E. Erickson; E.H. Helmer; T.J. Brandeis; A.E. Lugo

2014-01-01

Litter chemistry varies across landscapes according to factors rarely examined simultaneously. We analyzed 11 elements in forest floor (fallen) leaves and additional litter components from 143 forest inventory plots systematically located across Puerto Rico, a tropical island recovering from large-scale forest clearing. We assessed whether three existing, independently...

Chemistry and decomposition of litter from Populus tremuloides Michaux grown at elevated atmospheric CO2and varying N availability

Treesearch

John S. King; Kurt S. Pregitzer; Donald R. Zak; Mark E. Kubiske; Jennifer A. Ashby; William E. Holmes

2001-01-01

It has been hypothesized that greater production of total nonstructural carbohydrates (TNC) in foliage grown under elevated atmospheric carbon dioxide (CO2) will result in higher concentrations of defensive compounds in tree leaf litter, possibly leading to reduced rates of decomposition and nutrient cycling in forest ecosystems of the future....

Independent, interactive, and species-specific responses of leaf litter decomposition to elevated CO2 and O3 in a northern hardwood forest

Treesearch

William F.J. Parsons; James G. Bockheim; Richard L. Lindroth

2008-01-01

The future capacity of forest ecosystems to sequester atmospheric carbon is likely to be influenced by CO2-mediated shifts in nutrient cycling through changes in litter chemistry, and by interactions with pollutants like O3. We evaluated the independent and interactive effects of elevated CO2 and O...

Silvicultural management within streamside management zones of intermittent streams: effects on decomposition, productivity, nutrient cycling, and channel vegetation

Treesearch

R. Governo; B. G. Lockaby; Robert B. Rummer; C. Colson

2004-01-01

The purpose of this watershed study on three intermittent streams was to evaluate responses of riparian processes to three streamside management zone (SMZ) treatments; no harvest, clearcut, and partial hawest (50% basal area removal). Riparian response variables measured included litter$all, leaf litter decomposition, understory vegetation, soil temperature and water...

Litter Decomposition and Soil Respiration Responses to Fuel-Reduction Treatments in Piedmond Loblolly Pine Forests

Treesearch

Mac A. Callaham; Peter H. Anderson; Thomas A. Waldrop; Darren J. Lione; Victor B. Shelburne

2004-01-01

As part of the National Fire and Fire Surrogate Study, we measured the short-term effects of different fuel-management practices on leaf litter decomposition and soil respiration in loblolly pine stands on the upper Piedmont of South Carolina. These stands had been subjected to a factorial arrangement of experimental fuel-management treatments that included prescribed...

[Litter decomposition and nutrient release in Acacia mangium plantations established on degraded soils of Colombia].

PubMed

Castellanos-Barliza, Jeiner; León Peláez, Juan Diego

2011-03-01

Several factors control the decomposition in terrestrial ecosystems such as humidity, temperature, quality of litter and microbial activity. We investigated the effects of rainfall and soil plowing prior to the establishment of Acacia mangium plantations, using the litterbag technique, during a six month period, in forests plantations in Bajo Cauca region, Colombia. The annual decomposition constants (k) of simple exponential model, oscillated between 1.24 and 1.80, meanwhile k1 y k2 decomposition constants of double exponential model were 0.88-1.81 and 0.58-7.01. At the end of the study, the mean residual dry matter (RDM) was 47% of the initial value for the three sites. We found a slow N, Ca and Mg release pattern from the A. mangium leaf litter, meanwhile, phosphorus (P) showed a dominant immobilization phase, suggesting its low availability in soils. Chemical leaf litter quality parameters (e.g. N and P concentrations, C/N, N/P ratios and phenols content) showed an important influence on decomposition rates. The results of this study indicated that rainfall plays an important role on the decomposition process, but not soil plowing.

Evaluation of leaf litter leaching kinetics through commonly-used mathematical models

NASA Astrophysics Data System (ADS)

Montoya, J. V.; Bastianoni, A.; Mendez, C.; Paolini, J.

2012-04-01

Leaching is defined as the abiotic process by which soluble compounds of the litter are released into the water. Most studies dealing with leaf litter breakdown and leaching kinetics apply the single exponential decay model since it corresponds well with the understanding of the biology of decomposition. However, during leaching important mass losses occur and mathematical models often fail in describing this process adequately. During the initial hours of leaching leaf litter experience high decay rates which are not properly modelled. Adjusting leaching losses to mathematical models has not been investigated thoroughly and the use of models assuming constant decay rates leads to inappropriate assessments of leaching kinetics. We aim to describe, assess, and compare different leaching kinetics models fitted to leaf litter mass losses from six Neotropical riparian forest species. Leaf litter from each species was collected in the lower reaches of San Miguel stream in Northern Venezuela. Air-dried leaves from each species were incubated in 250 ml of water in the dark at room temperature. At 1h, 6h, 1d, 2d, 4d, 8d and 15d, three jars were removed from the assay in a no-replacement experimental design. At each time leaves from each jar were removed and oven-dried. Afterwards, dried up leaves were weighed and remaining dry mass was determined and expressed as ash-free dry mass. Mass losses of leaf litter showed steep declines for the first two days followed by a steady decrease in mass loss. Data was fitted to three different models: single-exponential, power and rational. Our results showed that the mass loss predicted with the single-exponential model did not reflect the real data at any stage of the leaching process. The power model showed a better adjustment, but fails predicting successfully the behavior during leaching's early stages. To evaluate the performance of our models we used three criteria: Adj-R2, Akaike's Information Criteria (AIC), and residual distribution. Higher Adj-R2 were obtained for the power and the rational-type models. However, when AIC and residuals distribution were used, the only model that could satisfactory predict the behavior of our dataset was the rational-type. Even if the Adj-R2 was higher for some species when using the power model compared to the rational-type; our results showed that this criterion alone cannot demonstrate the predicting performance of any model. Usually Adj-R2 is used when assessing the goodness of fit for any mathematical model disregarding the fact that a good Adj-R2 could be obtained even when statistical assumptions required for the validity of the model are not satisfied. Our results showed that sampling at the initial stages of leaching is necessary to adequately describe this process. We also provided evidence that using traditional mathematical models is not the best option to evaluate leaching kinetics because of its mathematical inability to properly describe the abrupt changes that occur during the early stages of leaching. We also found useful applying different criteria to evaluate the goodness-of-fit and performance of any model considered taking into account both statistical and biological meaning of the results.

Herbivore-mediated material fluxes in a northern deciduous forest under elevated carbon dioxide and ozone concentrations.

PubMed

Meehan, Timothy D; Couture, John J; Bennett, Alison E; Lindroth, Richard L

2014-10-01

Anthropogenic changes in atmospheric carbon dioxide (CO2 ) and ozone (O3 ) are known to alter tree physiology and growth, but the cascading effects on herbivore communities and herbivore-mediated nutrient cycling are poorly understood. We sampled herbivore frass, herbivore-mediated greenfall, and leaf-litter deposition in temperate forest stands under elevated CO2 (c. 560 ppm) and O3 (c. 1.5× ambient), analyzed substrate chemical composition, and compared the quality and quantity of fluxes under multiple atmospheric treatments. Leaf-chewing herbivores fluxed 6.2 g m(-2)  yr(-1) of frass and greenfall from the canopy to the forest floor, with a carbon : nitrogen (C : N) ratio 32% lower than that of leaf litter. Herbivore fluxes of dry matter, C, condensed tannins, and N increased under elevated CO2 (35, 32, 63 and 39%, respectively), while fluxes of N decreased (18%) under elevated O3 . Herbivore-mediated dry matter inputs scaled across atmospheric treatments as a constant proportion of leaf-litter inputs. Increased fluxes under elevated CO2 were consistent with increased herbivore consumption and abundance, and with increased plant growth and soil respiration, previously reported for this experimental site. Results suggest that insect herbivory will reinforce other factors, such as photosynthetic rate and fine-root production, impacting C sequestration by forests in future environments. © 2014 The Authors New Phytologist © 2014 New Phytologist Trust.

Trees as templates for tropical litter arthropod diversity.

PubMed

Donoso, David A; Johnston, Mary K; Kaspari, Michael

2010-09-01

Increased tree species diversity in the tropics is associated with even greater herbivore diversity, but few tests of tree effects on litter arthropod diversity exist. We studied whether tree species influence patchiness in diversity and abundance of three common soil arthropod taxa (ants, gamasid mites, and oribatid mites) in a Panama forest. The tree specialization hypothesis proposes that tree-driven habitat heterogeneity maintains litter arthropod diversity. We tested whether tree species differed in resource quality and quantity of their leaf litter and whether more heterogeneous litter supports more arthropod species. Alternatively, the abundance-extinction hypothesis states that arthropod diversity increases with arthropod abundance, which in turn tracks resource quantity (e.g., litter depth). We found little support for the hypothesis that tropical trees are templates for litter arthropod diversity. Ten tree species differed in litter depth, chemistry, and structural variability. However, the extent of specialization of invertebrates on particular tree taxa was low and the more heterogeneous litter between trees failed to support higher arthropod diversity. Furthermore, arthropod diversity did not track abundance or litter depth. The lack of association between tree species and litter arthropods suggests that factors other than tree species diversity may better explain the high arthropod diversity in tropical forests.

Riparian plant litter quality increases with latitude.

PubMed

Boyero, Luz; Graça, Manuel A S; Tonin, Alan M; Pérez, Javier; J Swafford, Andrew; Ferreira, Verónica; Landeira-Dabarca, Andrea; A Alexandrou, Markos; Gessner, Mark O; McKie, Brendan G; Albariño, Ricardo J; Barmuta, Leon A; Callisto, Marcos; Chará, Julián; Chauvet, Eric; Colón-Gaud, Checo; Dudgeon, David; Encalada, Andrea C; Figueroa, Ricardo; Flecker, Alexander S; Fleituch, Tadeusz; Frainer, André; Gonçalves, José F; Helson, Julie E; Iwata, Tomoya; Mathooko, Jude; M'Erimba, Charles; Pringle, Catherine M; Ramírez, Alonso; Swan, Christopher M; Yule, Catherine M; Pearson, Richard G

2017-09-05

Plant litter represents a major basal resource in streams, where its decomposition is partly regulated by litter traits. Litter-trait variation may determine the latitudinal gradient in decomposition in streams, which is mainly microbial in the tropics and detritivore-mediated at high latitudes. However, this hypothesis remains untested, as we lack information on large-scale trait variation for riparian litter. Variation cannot easily be inferred from existing leaf-trait databases, since nutrient resorption can cause traits of litter and green leaves to diverge. Here we present the first global-scale assessment of riparian litter quality by determining latitudinal variation (spanning 107°) in litter traits (nutrient concentrations; physical and chemical defences) of 151 species from 24 regions and their relationships with environmental factors and phylogeny. We hypothesized that litter quality would increase with latitude (despite variation within regions) and traits would be correlated to produce 'syndromes' resulting from phylogeny and environmental variation. We found lower litter quality and higher nitrogen:phosphorus ratios in the tropics. Traits were linked but showed no phylogenetic signal, suggesting that syndromes were environmentally determined. Poorer litter quality and greater phosphorus limitation towards the equator may restrict detritivore-mediated decomposition, contributing to the predominance of microbial decomposers in tropical streams.

Walker Branch Throughfall Displacement Experiment Data Report: Site Characterization, System Performance, Weather, Species Composition, and Growth (NDP-078 and 078A)

DOE Data Explorer

Cushman, Robert M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States), Carbon Dioxide Information Analysis Center, Environmental Sciences Division; Hanson, Paul J. [Oak Ridge National Laboratory, Oak Ridge, TN (USA), Environmental Sciences Division; Todd, Donald E. [Oak Ridge National Laboratory, Oak Ridge, TN (USA), Environmental Sciences Division; Riggs, Jeffery S. [Oak Ridge National Laboratory, Oak Ridge, TN (USA), Instrumentation and Controls Division; Wolfe, Mark E. [Tennessee Valley Authority, Norris, TN (USA); O'Neill, Elizabeth G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States), Environmental Sciences Division

2001-07-01

This numeric data package provides data sets, and accompanying documentation, on site characterization, system performance, weather, species composition, and growth for the Throughfall Displacement Experiment, which was established in the Walker Branch Watershed of East Tennessee to provide data on the responses of forests to altered precipitation regimes. The specific data sets include soil water content and potential, coarse fraction of the soil profile, litter layer temperature, soil temperature, monthly weather, daily weather, hourly weather, species composition of trees and saplings, mature tree and sapling annual growth, and relative leaf area index. Fortran and SAS(TM) access codes are provided to read the ASCII data files.

Plant species traits are the predominant control on litter decomposition rates within biomes worldwide.

PubMed

Cornwell, William K; Cornelissen, Johannes H C; Amatangelo, Kathryn; Dorrepaal, Ellen; Eviner, Valerie T; Godoy, Oscar; Hobbie, Sarah E; Hoorens, Bart; Kurokawa, Hiroko; Pérez-Harguindeguy, Natalia; Quested, Helen M; Santiago, Louis S; Wardle, David A; Wright, Ian J; Aerts, Rien; Allison, Steven D; van Bodegom, Peter; Brovkin, Victor; Chatain, Alex; Callaghan, Terry V; Díaz, Sandra; Garnier, Eric; Gurvich, Diego E; Kazakou, Elena; Klein, Julia A; Read, Jenny; Reich, Peter B; Soudzilovskaia, Nadejda A; Vaieretti, M Victoria; Westoby, Mark

2008-10-01

Worldwide decomposition rates depend both on climate and the legacy of plant functional traits as litter quality. To quantify the degree to which functional differentiation among species affects their litter decomposition rates, we brought together leaf trait and litter mass loss data for 818 species from 66 decomposition experiments on six continents. We show that: (i) the magnitude of species-driven differences is much larger than previously thought and greater than climate-driven variation; (ii) the decomposability of a species' litter is consistently correlated with that species' ecological strategy within different ecosystems globally, representing a new connection between whole plant carbon strategy and biogeochemical cycling. This connection between plant strategies and decomposability is crucial for both understanding vegetation-soil feedbacks, and for improving forecasts of the global carbon cycle.

Chronic impacts of TiO2 nanoparticles on Populus nigra L. leaf decomposition in freshwater ecosystem.

PubMed

Du, Jingjing; Zhang, Yuyan; Guo, Wei; Li, Ningyun; Gao, Chaoshuai; Cui, Minghui; Lin, Zhongdian; Wei, Mingbao; Zhang, Hongzhong

2018-05-15

Titanium dioxide (TiO 2 ) nanoparticles have been applied in diverse commercial products, which could lead to toxic effects on aquatic microbes and would inhibit some important ecosystem processes. The study aimed to investigate the chronic impacts of TiO 2 nanoparticles with different concentrations (5, 50, and 500 mg L -1 ) on Populus nigra L. leaf decomposition in the freshwater ecosystem. After 50 d of decomposing, a significant decrease in decomposition rates was observed with higher concentrations of TiO 2 nanoparticles. During the period of litter decomposition, exposure of TiO 2 nanoparticles led to decreases in extracellular enzyme activities, which was caused by the reduction of microbial especially fungal biomass. In addition, the diversity and composition of the fungal community associated with litter decomposition were strongly affected by the concentrations of TiO 2 nanoparticles. The diversity and composition of the fungal community associated with litter decomposition was strongly affected. The abundance of Tricladium chaetocladium decreased with the increasing concentrations of TiO 2 nanoparticles, indicating the little contribution of the species to the litter decomposition. In conclusion, this study provided the evidence for the chronic exposure effects of TiO 2 nanoparticles on the litter decomposition and further the functions of freshwater ecosystems. Copyright © 2018 Elsevier B.V. All rights reserved.

Facilitative and inhibitory effect of litter on seedling emergence and early growth of six herbaceous species in an early successional old field ecosystem.

PubMed

Li, Qiang; Yu, Pujia; Chen, Xiaoying; Li, Guangdi; Zhou, Daowei; Zheng, Wei

2014-01-01

In the current study, a field experiment was conducted to examine effects of litter on seedling emergence and early growth of four dominant weed species from the early successional stages of old field ecosystem and two perennial grassland species in late successional stages. Our results showed that increased litter cover decreased soil temperature and temperature variability over time and improved soil moisture status. Surface soil electrical conductivity increased as litter increased. The increased litter delayed seedling emergence time and rate. The emergence percentage of seedlings and establishment success rate firstly increased then decreased as litter cover increased. When litter biomass was below 600 g m(-2), litter increased seedlings emergence and establishment success in all species. With litter increasing, the basal diameter of seedling decreased, but seedling height increased. Increasing amounts of litter tended to increase seedling dry weight and stem leaf ratio. Different species responded differently to the increase of litter. Puccinellia tenuiflora and Chloris virgata will acquire more emergence benefits under high litter amount. It is predicted that Chloris virgata will dominate further in this natural succession old field ecosystem with litter accumulation. Artificial P. tenuiflora seeds addition may be required to accelerate old field succession toward matured grassland.

Facilitative and Inhibitory Effect of Litter on Seedling Emergence and Early Growth of Six Herbaceous Species in an Early Successional Old Field Ecosystem

PubMed Central

Li, Qiang; Yu, Pujia; Chen, Xiaoying; Li, Guangdi; Zhou, Daowei; Zheng, Wei

2014-01-01

In the current study, a field experiment was conducted to examine effects of litter on seedling emergence and early growth of four dominant weed species from the early successional stages of old field ecosystem and two perennial grassland species in late successional stages. Our results showed that increased litter cover decreased soil temperature and temperature variability over time and improved soil moisture status. Surface soil electrical conductivity increased as litter increased. The increased litter delayed seedling emergence time and rate. The emergence percentage of seedlings and establishment success rate firstly increased then decreased as litter cover increased. When litter biomass was below 600 g m−2, litter increased seedlings emergence and establishment success in all species. With litter increasing, the basal diameter of seedling decreased, but seedling height increased. Increasing amounts of litter tended to increase seedling dry weight and stem leaf ratio. Different species responded differently to the increase of litter. Puccinellia tenuiflora and Chloris virgata will acquire more emergence benefits under high litter amount. It is predicted that Chloris virgata will dominate further in this natural succession old field ecosystem with litter accumulation. Artificial P. tenuiflora seeds addition may be required to accelerate old field succession toward matured grassland. PMID:25110722

Microhabitat associations of a semi-terrestrial fish, Kryptolebias marmoratus (Poey 1880) in a mosquito-ditched mangrove forest, west-central Florida

USGS Publications Warehouse

Richards, Travis M.; Krebs, Justin M.; McIvor, Carole C.

2011-01-01

Mangrove rivulus (Kryptolebias marmoratus) is one of the few species of fish that is semi-terrestrial and able to use exposed intertidal and potentially supratidal habitats for prolonged periods of time. Based on previous work demonstrating frequent use of subterranean crab burrows as well as damp leaf litter and logs, we examined the microhabitat associations of rivulus in a mosquito-ditched mangrove forest on the Gulf coast of Florida near the northern limit of its distribution. We captured 161 rivulus on 20 dates between late April and mid-December 2007 using trench traps. Fish ranged in size from 7 to 35 mm SL. Peak abundance in mid-summer coincided with recruitment of a new year-class. The three study sites occurred within 0.5 km of one another, and experienced similar water temperatures and salinities. Nevertheless, they differed in their degree of tidal inundation, standing stock of leaf litter, and density of entrances to fiddler crab burrows. We consistently observed the highest mean catches of rivulus away from permanent subtidal waters of mosquito ditches, at intermediate relative elevations, and where leaf litter was locally abundant. Density of entrances to crab burrows was apparently unrelated to rivulus distribution or abundance in these forests.

Long-Term Simulated Atmospheric Nitrogen Deposition Alters ...

EPA Pesticide Factsheets

Atmospheric nitrogen deposition has been suggested to increase forest carbon sequestration across much of the Northern Hemisphere; slower organic matter decomposition could contribute to this increase. At four sugar maple (Acer saccharum)-dominated northern hardwood forests, we previously observed that 10 years of chronic simulated nitrogen deposition (30 kg N ha-1 yr-1) increased soil organic carbon. Over three years at these sites, we investigated the effects of nitrogen additions on decomposition of two substrates with documented differences in biochemistry: leaf litter (more labile) and fine roots (more recalcitrant). Further, we combined decomposition rates with annual leaf and fine root litter production to estimate how nitrogen additions altered the accumulation of soil organic matter. Nitrogen additions marginally stimulated early-stage decomposition of leaf litter, a substrate with little acid-insoluble material (e.g., lignin). In contrast, nitrogen additions inhibited the late stage decomposition of fine roots, a substrate with high amount of acid insoluble material and a change consistent with observed decreases in lignin-degrading enzyme activities with nitrogen additions at these sites. At the ecosystem scale, the slower fine root decomposition led to additional root mass retention (g m-2), which explained 5, 48, and 52 % of previously-documented soil carbon accumulation due to nitrogen additions. Our results demonstrated that nitrogen deposition ha

[Decomposition dynamics of leaf litter in logging residue of a secondary Castanopsis carlesii plantation and its chemical composition changes].

PubMed

Ren, Wei-ling; Guo, Jian-fen; Wu, Bo-bo; Wan, Jing-juan; Ji, Shu-rong; Liu, Xiao-fei

2015-04-01

A field experiment was conducted to understand the decomposition rates and chemical composition changes of leaf litter in logging residues of a 35-year-old secondary Castanopsis carlesii plantation over a period of one year. Mass loss rate of leaf litter showed an exponential decrease with time from May 2012 to April 2013, with a total 80% loss of initial dry mass. Net potassium (K) release was observed during this period, with only 5% of initial K remained. Nitrogen ( N) featured a pattern of accumulation at the early stage and release later, while phosphorus (P) exhibited a sequence of release, accumulation, and release. The remaining of N and P were 19% and 16% of their initial mass, respectively. The release rate was highest for K and the lowest for N. Decomposition of lignin indicated a trend of release-accumulation-release from May 2012 to October 2012, with no further significant change from November 2012 to the end of the experiment. The concentration of cellulose nearly unchanged during the experiment. The N/P rate increased with decomposition, ranging from 18.6 to 21.1. The lignin/N rate fluctuated greatly at the early stage and then almost stabilized thereafter.

Scale-dependent effects of nonnative plant invasion on host-seeking tick abundance

PubMed Central

Adalsteinsson, Solny A.; D’Amico, Vincent; Shriver, W. Gregory; Brisson, Dustin; Buler, Jeffrey J.

2016-01-01

Nonnative, invasive shrubs can affect human disease risk through direct and indirect effects on vector populations. Multiflora rose (Rosa multiflora) is a common invader within eastern deciduous forests where tick-borne disease (e.g. Lyme disease) rates are high. We tested whether R. multiflora invasion affects blacklegged tick (Ixodes scapularis) abundance, and at what scale. We sampled host-seeking ticks at two spatial scales: fine-scale, within R. multiflora-invaded forest fragments; and patch scale, among R. multiflora-invaded and R. multiflora-free forest fragments. At a fine scale, we trapped 2.3 times more ticks under R. multiflora compared to paired traps 25 m away from R. multiflora. At the patch scale, we trapped 3.2 times as many ticks in R. multiflora-free forests compared to R. multiflora-invaded forests. Thus, ticks are concentrated beneath R. multiflora within invaded forests, but uninvaded forests support significantly more ticks. Among all covariates tested, leaf litter volume was the best predictor of tick abundance; at the patch scale, R. multiflora-invaded forests had less leaf litter than uninvaded forests. We suggest that leaf litter availability at the patch-scale plays a greater role in constraining tick abundance than the fine-scale, positive effect of invasive shrubs. PMID:27088044

Tracking the evolution of stream DOM source during storm events using end member mixing analysis based on DOM quality

NASA Astrophysics Data System (ADS)

Yang, Liyang; Chang, Soon-Woong; Shin, Hyun-Sang; Hur, Jin

2015-04-01

The source of river dissolved organic matter (DOM) during storm events has not been well constrained, which is critical in determining the quality and reactivity of DOM. This study assessed temporal changes in the contributions of four end members (weeds, leaf litter, soil, and groundwater), which exist in a small forested watershed (the Ehwa Brook, South Korea), to the stream DOM during two storm events, using end member mixing analysis (EMMA) based on spectroscopic properties of DOM. The instantaneous export fluxes of dissolved organic carbon (DOC), chromophoric DOM (CDOM), and fluorescent components were all enhanced during peak flows. The DOC concentration increased with the flow rate, while CDOM and humic-like fluorescent components were diluted around the peak flows. Leaf litter was dominant for the DOM source in event 2 with a higher rainfall, although there were temporal variations in the contributions of the four end members to the stream DOM for both events. The contribution of leaf litter peaked while that of deeper soils decreased to minima at peak flows. Our results demonstrated that EMMA based on DOM properties could be used to trace the DOM source, which is of fundamental importance for understanding the factors responsible for river DOM dynamics during storm events.

Effects of inter and intraspecific diversity and genetic divergence of aquatic fungal communities on leaf litter decomposition-a microcosm experiment.

PubMed

Andrade, Ricardo; Pascoal, Cláudia; Cássio, Fernanda

2016-07-01

Freshwater fungi play a key role in plant litter decomposition and have been used to investigate the relationships between biodiversity and ecosystem functioning in streams. Although there is evidence of positive effects of biodiversity on ecosystem processes, particularly on biomass produced, some studies have shown that neutral or negative effects may occur. We manipulated the composition and the number of species and genotypes in aquatic fungal assemblages creating different levels of genetic divergence to assess effects of fungal diversity on biomass produced and leaf decomposition. Generally, diversity effects on fungal biomass produced were positive, suggesting complementarity between species, but in assemblages with more species positive diversity effects were reduced. Genotype diversity and genetic divergence had net positive effects on leaf mass loss, but in assemblages with higher diversity leaf decomposition decreased. Our results highlight the importance of considering multiple biodiversity measures when investigating the relationship between biodiversity and ecosystem functioning. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Heterogeneity in leaf litter decomposition in a temporary Mediterranean stream during flow fragmentation.

PubMed

Abril, Meritxell; Muñoz, Isabel; Menéndez, Margarita

2016-05-15

In temporary Mediterranean streams, flow fragmentation during summer droughts originates an ephemeral mosaic of terrestrial and aquatic habitat types. The heterogeneity of habitat types implies a particular ecosystem functioning in temporary streams that is still poorly understood. We assessed the initial phases of leaf litter decomposition in selected habitat types: running waters, isolated pools and moist and dry streambed sediments. We used coarse-mesh litter bags containing Populus nigra leaves to examine decomposition rates, microbial biomass, macroinvertebrate abundance and dissolved organic carbon (DOC) release rates in each habitat type over an 11-day period in late summer. We detected faster decomposition rates in aquatic (running waters and isolated pools) than in terrestrial habitats (moist and dry streambed sediments). Under aquatic conditions, decomposition was characterized by intense leaching and early microbial colonization, which swiftly started to decompose litter. Microbial colonization in isolated pools was primarily dominated by bacteria, whereas in running waters fungal biomass predominated. Under terrestrial conditions, leaves were most often affected by abiotic processes that resulted in small mass losses. We found a substantial decrease in DOC release rates in both aquatic habitats within the first days of the study, whereas DOC release rates remained relatively stable in the moist and dry sediments. This suggests that leaves play different roles as a DOC source during and after flow fragmentation. Overall, our results revealed that leaf decomposition is heterogeneous during flow fragmentation, which has implications related to DOC utilization that should be considered in future regional carbon budgets. Copyright © 2016 Elsevier B.V. All rights reserved.

Availability of residual phosphorus from broiler litter ash and layer manure ash amended soil for Paspalum vaginatum uptake

USDA-ARS?s Scientific Manuscript database

It has been hypothesized by several scientists that poultry litter ash could be used as a slow releasing phosphorus fertilizer that will become available over time. To test this hypothesis, a greenhouse study was conducted using a broiler litter ash, layer manure ash and calcium phosphate to determ...

[Microelement contents of litter, soil fauna and soil in Pinus koraiensis and broad-leaved mixed forest].

PubMed

Yin, Xiu-qin; Li, Jin-xia; Dong, Wei-hua

2007-02-01

The analysis on the Mn, Zn and Cu contents of litter, soil fauna and soil in Pinus korazenszis and broad-leaved mixed forest in Liangshui Natural Reserve of Xiaoxing' an Mountains showed that the test microelement contents in the litter, soil fauna and soil all followed the sequence of Mn > Zn > Cu, but varied with these environmental components, being in the sequence of soil > litter > soil fauna for Mn, soil fauna > litter and soil for Zn, and soil fauna > soil > litter for Cu. The change range of test microelement contents in litter was larger in broad-leaved forest than in coniferous forest. Different soil fauna differed in their microelement-enrichment capability, e. g. , earthworm, centipede, diplopod had the highest content of Mn, Zn and Cu, respectively. The contents of test microelements in soil fauna had significant correlations with their environmental background values, litter decomposition rate, food habit of soil fauna, and its absorbing selectivity and enrichment to microelements. The microelements contained in 5-20 cm soil layer were more than those in 0-5 cm soil layer, and their dynamics differed in various soil layers.

[Fire behavior of Quercus mongolica leaf litter fuelbed under zero-slope and no-wind conditions. II. Analysis and modelling of fireline intensity, fuel consumption, and combustion efficiency].

PubMed

Zhang, Ji-Li; Liu, Bo-Fei; Di, Xue-Ying; Chu, Teng-Fei; Jin, Sen

2013-12-01

Mongolian oak (Quercus mongolica) is an important constructive and accompanying species in mixed broadleaf-conifer forest in Northeast China, In this paper, a laboratory burning experiment was conducted under zero-slope and no-wind conditions to study the effects of fuel moisture content, loading, and thickness on the fireline intensity, fuel consumption, and combustion efficiency of the Mongolian oak leaf litter fuelbed. The fuel moisture content, loading, and thickness all had significant effects on the three fire behavior indices, and there existed interactions between these three affecting factors. Among the known models, the Byram model could be suitable for the prediction of local leaf litter fire intensity only after re-parameterization. The re-estimated alpha and beta parameters of the re-parameterized Byram model were 98.009 and 1.099, with an adjusted determination coefficient of 0.745, the rooted mean square error (RMSE) of 8.676 kW x m(-1), and the mean relative error (MRE) of 21%, respectively (R2 = 0.745). The re-estimated a and b by the burning efficiency method proposed by Albini were 0.069 and 0.169, and the re-estimated values were all higher than 93%, being mostly overestimated. The Consume model had a stronger suitability for the fuel. The R2 of the general linear models established for fireline intensity, fuel consumption, and burning efficiency was 0.82, 0.73 and 0.53, and the RMSE was 8.266 kW x m(-1) 0.081 kg x m(-2), and 0.203, respectively. In low intensity surface fires, the fine fuels could not be completely consumed, and thus, to consider the leaf litter and fine fuel in some forest ecosystems being completely consumed would overestimate the carbon release from forest fires.

Breeding Guild Determines Frog Distributions in Response to Edge Effects and Habitat Conversion in the Brazil's Atlantic Forest.

PubMed

Ferreira, Rodrigo B; Beard, Karen H; Crump, Martha L

2016-01-01

Understanding the response of species with differing life-history traits to habitat edges and habitat conversion helps predict their likelihood of persistence across changing landscape. In Brazil's Atlantic Forest, we evaluated frog richness and abundance by breeding guild at four distances from the edge of a reserve: i) 200 m inside the forest, ii) 50 m inside the forest, iii) at the forest edge, and iv) 50 m inside three different converted habitats (coffee plantation, non-native Eucalyptus plantation, and abandoned pastures, hereafter matrix types). By sampling a dry and a wet season, we recorded 622 individual frogs representing 29 species, of which three were undescribed. Breeding guild (i.e. bromeliad, leaf-litter, and water-body breeders) was the most important variable explaining frog distributions in relation to edge effects and matrix types. Leaf-litter and bromeliad breeders decreased in richness and abundance from the forest interior toward the matrix habitats. Water-body breeders increased in richness toward the matrix and remained relatively stable in abundance across distances. Number of large trees (i.e. DBH > 15 cm) and bromeliads best explained frog richness and abundance across distances. Twenty species found in the interior of the forest were not found in any matrix habitat. Richness and abundance across breeding guilds were higher in the rainy season but frog distributions were similar across the four distances in the two seasons. Across matrix types, leaf-litter species primarily used Eucalyptus plantations, whereas water-body species primarily used coffee plantations. Bromeliad breeders were not found inside any matrix habitat. Our study highlights the importance of primary forest for bromeliad and leaf-litter breeders. We propose that water-body breeders use edge and matrix habitats to reach breeding habitats along the valleys. Including life-history characteristics, such as breeding guild, can improve predictions of frog distributions in response to edge effect and matrix types, and can guide more effective management and conservation actions.

Breeding Guild Determines Frog Distributions in Response to Edge Effects and Habitat Conversion in the Brazil’s Atlantic Forest

PubMed Central

Ferreira, Rodrigo B.; Beard, Karen H.; Crump, Martha L.

2016-01-01

Understanding the response of species with differing life-history traits to habitat edges and habitat conversion helps predict their likelihood of persistence across changing landscape. In Brazil’s Atlantic Forest, we evaluated frog richness and abundance by breeding guild at four distances from the edge of a reserve: i) 200 m inside the forest, ii) 50 m inside the forest, iii) at the forest edge, and iv) 50 m inside three different converted habitats (coffee plantation, non-native Eucalyptus plantation, and abandoned pastures, hereafter matrix types). By sampling a dry and a wet season, we recorded 622 individual frogs representing 29 species, of which three were undescribed. Breeding guild (i.e. bromeliad, leaf-litter, and water-body breeders) was the most important variable explaining frog distributions in relation to edge effects and matrix types. Leaf-litter and bromeliad breeders decreased in richness and abundance from the forest interior toward the matrix habitats. Water-body breeders increased in richness toward the matrix and remained relatively stable in abundance across distances. Number of large trees (i.e. DBH > 15 cm) and bromeliads best explained frog richness and abundance across distances. Twenty species found in the interior of the forest were not found in any matrix habitat. Richness and abundance across breeding guilds were higher in the rainy season but frog distributions were similar across the four distances in the two seasons. Across matrix types, leaf-litter species primarily used Eucalyptus plantations, whereas water-body species primarily used coffee plantations. Bromeliad breeders were not found inside any matrix habitat. Our study highlights the importance of primary forest for bromeliad and leaf-litter breeders. We propose that water-body breeders use edge and matrix habitats to reach breeding habitats along the valleys. Including life-history characteristics, such as breeding guild, can improve predictions of frog distributions in response to edge effect and matrix types, and can guide more effective management and conservation actions. PMID:27272328

The surrounding landscape influences the diversity of leaf-litter ants in riparian cloud forest remnants.

PubMed

García-Martínez, Miguel Á; Valenzuela-González, Jorge E; Escobar-Sarria, Federico; López-Barrera, Fabiola; Castaño-Meneses, Gabriela

2017-01-01

Riparian vegetation is a distinctive and ecologically important element of landscapes worldwide. However, the relative influence of the surrounding landscape on the conservation of the biodiversity of riparian remnants in human-modified tropical landscapes is poorly understood. We studied the surrounding landscape to evaluate its influence on leaf-litter-ant alpha and beta diversity in riparian remnants in the tropical montane cloud forest region of central Veracruz, Mexico. Sampling was carried out in 12 sites with riparian vegetation during both rainy (2011) and dry (2012) seasons. Ten leaf-litter samples were collected along a 100-m transect per site and processed with Berlese-Tullgren funnels and Winkler sacks. Using remotely-sensed and ground-collected data, we characterized the landscape around each site according to nine land cover types and computed metrics of landscape composition and configuration. We collected a total of 8,684 ant individuals belonging to 53 species, 22 genera, 11 tribes, and 7 subfamilies. Species richness and the diversity of Shannon and Simpson increased significantly in remnants immersed in landscapes with a high percentage of riparian land cover and a low percentage of land covers with areas reforested with Pinus, cattle pastures, and human settlements and infrastructure. The composition of ant assemblages was a function of the percentage of riparian land cover in the landscape. This study found evidence that leaf-litter ants, a highly specialized guild of arthropods, are mainly impacted by landscape composition and the configuration of the focal remnant. Maintaining or improving the surrounding landscape quality of riparian vegetation remnants can stimulate the movement of biodiversity among forest and riparian remnants and foster the provision of ecosystem services by these ecosystems. Effective outcomes may be achieved by considering scientific knowledge during the early stages of riparian policy formulation, in addition to integrating riparian management strategies with broader environmental planning instruments.

The surrounding landscape influences the diversity of leaf-litter ants in riparian cloud forest remnants

PubMed Central

Valenzuela-González, Jorge E.; Escobar-Sarria, Federico; López-Barrera, Fabiola; Castaño-Meneses, Gabriela

2017-01-01

Riparian vegetation is a distinctive and ecologically important element of landscapes worldwide. However, the relative influence of the surrounding landscape on the conservation of the biodiversity of riparian remnants in human-modified tropical landscapes is poorly understood. We studied the surrounding landscape to evaluate its influence on leaf-litter-ant alpha and beta diversity in riparian remnants in the tropical montane cloud forest region of central Veracruz, Mexico. Sampling was carried out in 12 sites with riparian vegetation during both rainy (2011) and dry (2012) seasons. Ten leaf-litter samples were collected along a 100-m transect per site and processed with Berlese-Tullgren funnels and Winkler sacks. Using remotely-sensed and ground-collected data, we characterized the landscape around each site according to nine land cover types and computed metrics of landscape composition and configuration. We collected a total of 8,684 ant individuals belonging to 53 species, 22 genera, 11 tribes, and 7 subfamilies. Species richness and the diversity of Shannon and Simpson increased significantly in remnants immersed in landscapes with a high percentage of riparian land cover and a low percentage of land covers with areas reforested with Pinus, cattle pastures, and human settlements and infrastructure. The composition of ant assemblages was a function of the percentage of riparian land cover in the landscape. This study found evidence that leaf-litter ants, a highly specialized guild of arthropods, are mainly impacted by landscape composition and the configuration of the focal remnant. Maintaining or improving the surrounding landscape quality of riparian vegetation remnants can stimulate the movement of biodiversity among forest and riparian remnants and foster the provision of ecosystem services by these ecosystems. Effective outcomes may be achieved by considering scientific knowledge during the early stages of riparian policy formulation, in addition to integrating riparian management strategies with broader environmental planning instruments. PMID:28234948

Does 'you are what you eat' apply to mangrove grapsid crabs?

PubMed

Bui, Thi Hong Hanh; Lee, Shing Yip

2014-01-01

In tropical mangroves, brachyuran crabs have been observed to consume high percentages of leaf litter production. However, questions concerning their ability to assimilate this low-quality food remain, as stable isotope analysis of C and N does not seem to support assimilation. Individuals of the common eastern Australian mangrove grapsid Parasesarma erythodactyla feeding on a mangrove leaf litter or mangrove+microphytobenthos diet developed a significantly higher hepatosomatic index than those with access to only sediment. Lipid biomarker analysis and feeding experiments using (13)C and (15)N-enriched mangrove leaf litter confirmed rapid assimilation of mangrove C and N by P. erythodactyla. Eight-week feeding experiments utilizing three food types (mangrove leaf litter, microphytobenthos and prawn muscle) established different food-specific trophic discrimination values (Δδ(13)C and Δδ(15)N) that are significantly different from those commonly applied to mixing model calculations. The mean Δδ(13)C(crab-mangrove) of +5.45‰ was close to the mean and median literature values for grapsid-mangrove pairs in 29 past studies (+5.2 ± 1.8‰ and +5.6‰, respectively), suggesting that this large discrimination may generally be characteristic of detritivorous grapsid crabs. Solutions from the IsoConc mixing model using our determined trophic discrimination values suggest significantly higher and dominant contributions of mangrove C to the diet than those based on the global mean trophic discrimination values. Our results reaffirm the physiological capacity for and important mediating role of grapsid crabs in processing low-quality mangrove C in tropical estuaries, and caution against the use of global trophic discrimination values in stable isotope analysis of food-web data, especially those involving detritivores. While recent studies have questioned the trophic significance of mangrove detritus in coastal food chains, the contribution of this productive carbon source needs to be re-assessed in the light of these data.

Does ‘You Are What You Eat’ Apply to Mangrove Grapsid Crabs?

PubMed Central

Bui, Thi Hong Hanh; Lee, Shing Yip

2014-01-01

In tropical mangroves, brachyuran crabs have been observed to consume high percentages of leaf litter production. However, questions concerning their ability to assimilate this low-quality food remain, as stable isotope analysis of C and N does not seem to support assimilation. Individuals of the common eastern Australian mangrove grapsid Parasesarma erythodactyla feeding on a mangrove leaf litter or mangrove+microphytobenthos diet developed a significantly higher hepatosomatic index than those with access to only sediment. Lipid biomarker analysis and feeding experiments using 13C and 15N-enriched mangrove leaf litter confirmed rapid assimilation of mangrove C and N by P. erythodactyla. Eight-week feeding experiments utilizing three food types (mangrove leaf litter, microphytobenthos and prawn muscle) established different food-specific trophic discrimination values (Δδ13C and Δδ15N) that are significantly different from those commonly applied to mixing model calculations. The mean Δδ13C(crab-mangrove) of +5.45‰ was close to the mean and median literature values for grapsid-mangrove pairs in 29 past studies (+5.2±1.8‰ and +5.6‰, respectively), suggesting that this large discrimination may generally be characteristic of detritivorous grapsid crabs. Solutions from the IsoConc mixing model using our determined trophic discrimination values suggest significantly higher and dominant contributions of mangrove C to the diet than those based on the global mean trophic discrimination values. Our results reaffirm the physiological capacity for and important mediating role of grapsid crabs in processing low-quality mangrove C in tropical estuaries, and caution against the use of global trophic discrimination values in stable isotope analysis of food-web data, especially those involving detritivores. While recent studies have questioned the trophic significance of mangrove detritus in coastal food chains, the contribution of this productive carbon source needs to be re-assessed in the light of these data. PMID:24551220

Effects of flow scarcity on leaf-litter processing under oceanic climate conditions in calcareous streams.

PubMed

Martínez, Aingeru; Pérez, Javier; Molinero, Jon; Sagarduy, Mikel; Pozo, Jesús

2015-01-15

Although temporary streams represent a high proportion of the total number and length of running waters, historically the study of intermittent streams has received less attention than that of perennial ones. The goal of the present study was to assess the effects of flow cessation on litter decomposition in calcareous streams under oceanic climate conditions. For this, leaf litter of alder was incubated in four streams (S1, S2, S3 and S4) with different flow regimes (S3 and S4 with zero-flow periods) from northern Spain. To distinguish the relative importance and contribution of decomposers and detritivores, fine- and coarse-mesh litter bags were used. We determined processing rates, leaf-C, -N and -P concentrations, invertebrate colonization in coarse bags and benthic invertebrates. Decomposition rates in fine bags were similar among streams. In coarse bags, only one of the intermittent streams, S4, showed a lower rate than that in the other ones as a consequence of lower invertebrate colonization. The material incubated in fine bags presented higher leaf-N and -P concentrations than those in the coarse ones, except in S4, pointing out that the decomposition in this stream was driven mainly by microorganisms. Benthic macroinvertebrate and shredder density and biomass were lower in intermittent streams than those in perennial ones. However, the bags in S3 presented a greater amount of total macroinvertebrates and shredders comparing with the benthos. The most suitable explanation is that the fauna find a food substrate in bags less affected by calcite precipitation, which is common in the streambed at this site. Decomposition rate in coarse bags was positively related to associated shredder biomass. Thus, droughts in streams under oceanic climate conditions affect mainly the macroinvertebrate detritivore activity, although macroinvertebrates may show distinct behavior imposed by the physicochemical properties of water, mainly travertine precipitation, which can override the flow intermittence effects. Copyright © 2014. Published by Elsevier B.V.

Resource stoichiometry and availability modulate species richness and biomass of tropical litter macro-invertebrates.

PubMed

Jochum, Malte; Barnes, Andrew D; Weigelt, Patrick; Ott, David; Rembold, Katja; Farajallah, Achmad; Brose, Ulrich

2017-09-01

High biodiversity and biomass of soil communities are crucial for litter decomposition in terrestrial ecosystems such as tropical forests. However, the leaf litter that these communities consume is of particularly poor quality as indicated by elemental stoichiometry. The impact of resource quantity, quality and other habitat parameters on species richness and biomass of consumer communities is often studied in isolation, although much can be learned from simultaneously studying both community characteristics. Using a dataset of 780 macro-invertebrate consumer species across 32 sites in tropical lowland rain forest and agricultural systems on Sumatra, Indonesia, we investigated the effects of basal resource stoichiometry (C:X ratios of N, P, K, Ca, Mg, Na, S in local leaf litter), litter mass (basal resource quantity and habitat space), plant species richness (surrogate for litter habitat heterogeneity), and soil pH (acidity) on consumer species richness and biomass across different consumer groups (i.e. 3 feeding guilds and 10 selected taxonomic groups). In order to distinguish the most important predictors of consumer species richness and biomass, we applied a standardised model averaging approach investigating the effects of basal resource stoichiometry, litter mass, plant species richness and soil pH on both consumer community characteristics. This standardised approach enabled us to identify differences and similarities in the magnitude and importance of such effects on consumer species richness and biomass. Across consumer groups, we found litter mass to be the most important predictor of both species richness and biomass. Resource stoichiometry had a more pronounced impact on consumer species richness than on their biomass. As expected, taxonomic groups differed in which resource and habitat parameters (basal resource stoichiometry, litter mass, plant species richness and pH) were most important for modulating their community characteristics. The importance of litter mass for both species richness and biomass indicates that these tropical consumers strongly depend on habitat space and resource availability. Our study supports previous theoretical work indicating that consumer species richness is jointly influenced by resource availability and the balanced supply of multiple chemical elements in their resources. © 2017 The Authors. Journal of Animal Ecology © 2017 British Ecological Society.

American Beech Leaf-litter Leachate Chemistry: Effects of Geography and Phenophase

NASA Astrophysics Data System (ADS)

Hudson, J. E.; Levia, D. F., Jr.; Wheeler, K. I.; Winters, C. G.; Vaughan, M.; Chace, J.; Sleeper, R.

2017-12-01

The decomposition of leaves from broadleaved trees contributes to the energy budget of forested watersheds via dissolved organic matter, nutrients, and biological activity. Although it is often implicitly assumed that intraspecific differences in leaf-litter leachate chemistry do not significantly differ geographically, we attempted to discern how these inputs may vary from single tree species that is known to have two genetically distinct and geographically separate populations, as well as how these inputs may change throughout autumn senescence and after abscission. We analyzed the physical and chemical leaf traits and leaf leachates of leaves from Fagus grandifolia (American beech; n = 360) during three phenophases: fresh green, senescing, and fallen. During each phenophase, leaves were collected from four sites along a geographic transect stretching from Vermont to North Carolina (over 1400 km), with two sites representing each genetic population and differing climatic conditions. Pooled leaf leachates from each site and phenophase were analyzed for routine solutes and nutrients, as well as fluorescent and UV-visible absorbance indices. Quantities of macro- and micronutrients were highly variable among sites and phenophases but tended to be lowest from fallen leaves, while measured fluorescence and absorbance indices tended to increase during leaves collected during senescence. Results suggest significant differences in leached nutrients among field sites, while optical properties and nutrients varied significantly among phenophases. Aromaticity and molecular weight of DOM in leachates was generally low, and aromaticity and humification of leachates both increased as leaves aged throughout the selected phenophases. Results also suggest that geographically (or genetically) separate populations of the same species do not experience senescence in the same way and that implicit assumptions of intraspecific uniformity of leaf-litter leachate chemistry for a given tree species may be invalid. Funding note: Research made possible by the U.S. National Science Foundation (Grant No. IIA-1330238, IIA-1330446, and IIA-1330406).

Effects of canopy opening and debris deposition on fungal connectivity, phosphorus movement between litter cohorts and mass loss

Treesearch

D. Jean Lodge; Sharon A. Cantrell; Grizelle Gonzalez

2014-01-01

Fungi are important for maintaining fast rates of decomposition in low quality tropical leaf litter via immobilization and translocation of limiting nutrients from sources to sinks and conserving nutrients after disturbance. Tropical trees often have low nutrient to carbon ratios. Disturbances such as hurricanes and logging transfer a large mass of green leaves with...

Long-term dynamics of pine and hardwood litter in contrasting environments: Toward a global model of decomposition

Treesearch

Henry L. Gholz; David A. Wedin; Stephen M. Smitherman; Mark E. Harmon; William J. Parton

2000-01-01

We analysed data on mass loss after five years of decomposition in the field from both fine root and leaf litters from two highly contrasting trees, Drypetes glallca, a tropical hardwood tree from Puerto Rico, and pine species from North America as part of the Long-Term Intersite Decomposition Experiment (LIDET). LIDET is a reciprocal litterbag study...

Litter Decomposition in Low and High Mortality Northern Red Oak Stands on Extremely Acidic Southwestern Pennsylvania Soils

Treesearch

Michael C. Demchik; William E. Sharpe

2004-01-01

Previous research has shown that decomposition of organic matter is slower in soils with high levels of soil acidity and available aluminum (Al). The objective of this experiment was to determine if differences in decomposition rates of northern red oak leaves occurred between extremely acidic and less acidic sites that also differed in oak mortality. Leaf litter from...

Global synthesis of the temperature sensitivity of leaf litter breakdown in streams and rivers.

PubMed

Follstad Shah, Jennifer J; Kominoski, John S; Ardón, Marcelo; Dodds, Walter K; Gessner, Mark O; Griffiths, Natalie A; Hawkins, Charles P; Johnson, Sherri L; Lecerf, Antoine; LeRoy, Carri J; Manning, David W P; Rosemond, Amy D; Sinsabaugh, Robert L; Swan, Christopher M; Webster, Jackson R; Zeglin, Lydia H

2017-08-01

Streams and rivers are important conduits of terrestrially derived carbon (C) to atmospheric and marine reservoirs. Leaf litter breakdown rates are expected to increase as water temperatures rise in response to climate change. The magnitude of increase in breakdown rates is uncertain, given differences in litter quality and microbial and detritivore community responses to temperature, factors that can influence the apparent temperature sensitivity of breakdown and the relative proportion of C lost to the atmosphere vs. stored or transported downstream. Here, we synthesized 1025 records of litter breakdown in streams and rivers to quantify its temperature sensitivity, as measured by the activation energy (E a , in eV). Temperature sensitivity of litter breakdown varied among twelve plant genera for which E a could be calculated. Higher values of E a were correlated with lower-quality litter, but these correlations were influenced by a single, N-fixing genus (Alnus). E a values converged when genera were classified into three breakdown rate categories, potentially due to continual water availability in streams and rivers modulating the influence of leaf chemistry on breakdown. Across all data representing 85 plant genera, the E a was 0.34 ± 0.04 eV, or approximately half the value (0.65 eV) predicted by metabolic theory. Our results indicate that average breakdown rates may increase by 5-21% with a 1-4 °C rise in water temperature, rather than a 10-45% increase expected, according to metabolic theory. Differential warming of tropical and temperate biomes could result in a similar proportional increase in breakdown rates, despite variation in E a values for these regions (0.75 ± 0.13 eV and 0.27 ± 0.05 eV, respectively). The relative proportions of gaseous C loss and organic matter transport downstream should not change with rising temperature given that E a values for breakdown mediated by microbes alone and microbes plus detritivores were similar at the global scale. © 2017 John Wiley & Sons Ltd.

Tree leaf control on low flow water quality in a small Virginia stream

USGS Publications Warehouse

Slack, K.V.; Feltz, H.R.

1968-01-01

Impaired water quality in a small stream was related to autumn leaf fall from riparian vegetation. Dissolved oxygen and pH decreased, and water color, specific conductance, iron, manganese, and bicarbonate values increased as the rate of leaf fall increased. Similar quality changes occurred in laboratory cultures of tree leaves in filtered stream water, but the five leaf species studied produced widely differing results. Stream quality improved rapidly following channel flushing by storm flow. Organic loading by tree litter can exert significant control on water composition, especially during low flow.

Effects of top-dressing recycled broiler litter on litter production, litter characteristics, and nitrogen mass balance.

PubMed

Coufal, C D; Chavez, C; Niemeyer, P R; Carey, J B

2006-03-01

Top-dressing is a method of broiler litter management in which a thin layer of new, clean litter material is spread over the top of previously used litter prior to placement of a new flock. This fresh layer of bedding material increases the absorptive capacity of the litter and decreases litter caking. Although this practice has been widely used in the poultry industry for many years, no research has been conducted to quantify the effects the practice has on broiler performance, litter production rates, and nutrient content, or the ability of broiler litter to retain manure N and prevent volatilization. An experiment was conducted to quantify these parameters under simulated commercial conditions in a research facility. Nine consecutive flocks of broilers were reared on recycled broiler litter that had previously been used for 9 flocks. Control pens received no litter treatment whereas top-dressed pens received a thin layer of new rice hulls (1 to 2 cm) before the placement of each flock. Nitrogen loss was calculated using the mass balance method. Average broiler performance was not different between the top-dressed and control pens. Top-dressing of litter significantly (P < 0.05) reduced caked litter production compared with control pens in 6 of 9 flocks. However, average total litter production over all 9 flocks was not different between the 2 litter management strategies. In all flocks, litter N content was significantly reduced in top-dressed pens compared with control pens. As a result, litter C:N ratios were significantly higher for pens with top-dressed litter. Differences in N loss between the treatments were not consistent. Average N loss for all flocks was 10.61 and 11.92 g of N/kg of marketed broiler for control and top-dressed pens, respectively, or 20.1 and 22.5% of N inputs, respectively. Based on this experiment, top-dressing of recycled broiler litter would not be recommended as a strategy to reduce the volatilization of N from broiler rearing facilities and, in fact, may actually increase N loss.

Experimental research on recolonisation with Anemone nemorosa of the beech forests of the Ruhr district (Germany) floristically impoverished by air pollution.

PubMed

Wittig, Rüdiger

2008-09-01

High SO(2) concentrations as have been observed over decades in the Ruhr district lead to a remarkable reduction of leaf area in the majority of the characteristic broad-leafed herbs of the Central European beech forests even after only a few months of experimental fumigation. Thus, it is no wonder in the time of high SO(2) pollution, e.g., in the town of Herne (centre of the Ruhr district), that there was not a single beech forest hosting, for instance, Viola reichenbachiana or Anemone nemorosa. As air quality has improved very much over some decades in the Ruhr district, one can expect a recolonisation of the beech forests by the species of former time characteristic for the herb layer. However, one has to consider that only the air pollution was reduced, while soil acidification and contamination with heavy metals and PAH are, on the short run, irreversible. That is why experiments were carried out, considering the question as to whether recolonisation of the forests of the Ruhr district by the aforementioned species is possible and why such a recolonisation up to now has not occurred. The experiments were carried out in a beech forest situated in the centre of the Ruhr district in the City of Herne. The wood anemone (A. nemorosa) was chosen as test plant because of its high frequency in beech forests on loess soils outside the Ruhr district, and its absence in beech forests in the Ruhr district. The experiments with A. nemorosa were carried out in three variants with different soils: (a): soil of the local forests (R); (b): soil of the local forests whose soot layer was removed (r); (c): imported soil from a clean air region far away from the Ruhr district (Odenwald). Survival of rhizomes of A. nemorosa is possible for some years in the soils of the Ruhr district; however, the establishment of a population could not be achieved. The results obtained by the imported soil show that it is no longer air pollution, but the soil which prevents the establishment of a population. Sexual reproduction is rather impossible because of the thick litter layer with which all of the Ruhr district's beech forests are covered. With respect to the unfavourable chemistry of the soil of the Ruhr district and in consideration of the unfavourable attributes of the soot layer, the author expected the following order of the development of shoot numbers: O > r > R. However, the result is: O > R > r. In contrast to the expected result, the soot layer has no negative but slightly positive effects on the implanted rhizomes. A possible explanation is that the soot layer, which is situated immediately below the top soil, prevents the top soil from drying up and thus even protects the rhizomes from desiccation. Also, the possibility has to be considered that the soot layer functions as a nutrient storage area. At present, a survival of the rhizomes of A. nemorosa in the soils of the Ruhr district is temporarily possible but does not lead to the establishment of a permanent population. This only can be achieved by additional sexual reproduction. However, the thick litter layer present in all beech forests of the Ruhr district prevents the establishment of seedlings, i.e., it does not allow sexual reproduction to contribute to the population. The soot layer situated below the litter layer represents a second hindrance for germination. Other than seedlings, rhizomes are not negatively affected by the soot layer but even a slight stabilisation has to be stated. As a reason for this slightly positive effect, a protection of the upper mineral soil from desiccation by the hydrophob soot layer has to be considered. Secondly, the soot layer may serve as a nutrient storage which is of particular importance in acid soils, because acidification generally leads to a leeching of nutrients. To answer these questions, detailed further research is necessary. In order to restore the formerly rich herbaceous layer of the forests of the Ruhr district, experiments (removal of the litter layer; liming; ploughing) should be carried out at broad-scale to solve the question of how the strong negative effects of the established thick raw humus layer can be reduced or even be avoided. When the problem of the humus layer is solved, the beech forests of the Ruhr district today highly impoverished in species will become a vivid ecosystem, rich in flowering herbaceous species and thus much more attractive for the people of the Ruhr district than at present.

Augmentation of freeze-thaw cycles in the alpine soil triggered by the fire on the alpine slopes, Mount Shirouma-dake, northern Japanese Alps

NASA Astrophysics Data System (ADS)

Sasaki, A.; Suzuki, K.

2015-12-01

This is the continuous study to clarify the geo-environmental changes on the post-fire alpine slopes of Mount Shirouma-dake in the northern Japanese Alps. The fire occurred at May 9, 2009 on the alpine slopes of Mount Shirouma-dake, and the fire spread to the Pinus pumila communities and grasslands. Although the grass had a little damage by the fire, the P. pumila received nearly impact of the fire. In the P. pumila communities where the leaf burnt, forest floor is exposed and become easy to be affected by atmospheric condition such as rain, wind, snow, and etc. First, we illustrated a map of micro-landforms, based on geomorphological fieldworks. We observed these micro-landforms repeatedly for fifth years after the fire. As the results of the observation, it is clear that remarkable changes of these micro-landforms have not occurred but some litters on the forest-floor in the P. pumila communities are flushed out to surroundings. The litter layer on the forest-floor in the P. pumila communities were 3-4 cm thick in August of 2011, but it became 0.5 cm thick in September of 2014. The P. pumila communities established on the slopes consists of angular and sub-angular gravel with openwork texture, which are covered by thin soil layer. Therefore, it is necessary to pay attention to soil erosion following the outflow of the litter. In addition, we observe the ground temperature and soil moisture, under the fired P. pumila communities and the no fired P. pumila communities after the fire, to find influence of the fire. The ground temperature sensors were installed into at 1 cm, 10 cm, and 40 cm depth. The soil moisture sensors were installed into at 1 cm and 10 cm depth. The 1 cm depth of the soil on the post-fire slopes, diurnal freeze-thaw cycles occurred in October and November of 2011, 2012, 2013, and 2014 but it had not occurred in 2009 and 2010. In addition, the period of seasonal frost at 10 cm and 40 cm depth on the post-fire slopes are extended for two weeks. These thermal condition changes are triggered by decrease in the thickness of the litter layer on the fired P. pumila communities.

Forest composition modifies litter dynamics and decomposition in regenerating tropical dry forest.

PubMed

Schilling, Erik M; Waring, Bonnie G; Schilling, Jonathan S; Powers, Jennifer S

2016-09-01

We investigated how forest composition, litter quality, and rainfall interact to affect leaf litter decomposition across three successional tropical dry forests in Costa Rica. We monitored litter stocks and bulk litter turnover in 18 plots that exhibit substantial variation in soil characteristics, tree community structure, fungal communities (including forests dominated by ecto- or arbuscular mycorrhizal host trees), and forest age. Simultaneously, we decomposed three standard litter substrates over a 6-month period spanning an unusually intense drought. Decay rates of standard substrates depended on the interaction between litter identity and forest type. Decomposition rates were correlated with tree and soil fungal community composition as well as soil fertility, but these relationships differed among litter types. In low fertility soils dominated by ectomycorrhizal oak trees, bulk litter turnover rates were low, regardless of soil moisture. By contrast, in higher fertility soils that supported mostly arbuscular mycorrhizal trees, bulk litter decay rates were strongly dependent on seasonal water availability. Both measures of decomposition increased with forest age, as did the frequency of termite-mediated wood decay. Taken together, our results demonstrate that soils and forest age exert strong control over decomposition dynamics in these tropical dry forests, either directly through effects on microclimate and nutrients, or indirectly by affecting tree and microbial community composition and traits, such as litter quality.

Decomposition rate of Rhizopora stylosa litter in Tanjung Rejo Village, Deli Serdang Regency, North Sumatera Province

NASA Astrophysics Data System (ADS)

Rambey, R.; Delvian; Sianturi, S. D.

2018-02-01

Research on the decomposition rate of Rhizopora stylosa litter in Tanjung Rejo village, Deli Serdang Regency, North Sumatera Province was conducted from September 2016 to May 2017. The objectives of this research were (1) to measure the decomposition rate of Rhizophora stylosa litter and (2) to determine the type of functional fungi in decomposition of litter. R. stylosa litter decomposition is characterized by a reduction in litter weight per observation period. Decomposition rate tended to increase every week, which was from 0.238 in the seventh day and reached 0.302 on the fiftysixthth day. The decomposition rate of R. stylosa litter of leaf was high with the value of k per day > 0,01 caused by macrobentos and fungi, and also the decomposition of R. stylosa litter conducted in the pond area which is classified far from the coast. Therefore, to enable the high population of fungi which affect the decomposition rate of the litter. The types of fungi decomposers were: Aspergillus sp.-1, Aspergillus sp.-2, Aspergillus sp.-3, Rhizophus sp.-1., Rhizophus sp.-2, Penicillium sp., Syncephalastrum sp. and Fusarium sp.

Biological decomposition efficiency in different woodland soils.

PubMed

Herlitzius, H

1983-03-01

The decomposition (meaning disappearance) of different leaf types and artificial leaves made from cellulose hydrate foil was studied in three forests - an alluvial forest (Ulmetum), a beech forest on limestone soil (Melico-Fagetum), and a spruce forest in soil overlying limestone bedrock.Fine, medium, and coarse mesh litter bags of special design were used to investigate the roles of abiotic factors, microorganisms, and meso- and macrofauna in effecting decomposition in the three habitats. Additionally, the experimental design was carefully arranged so as to provide information about the effects on decomposition processes of the duration of exposure and the date or moment of exposure. 1. Exposure of litter samples oor 12 months showed: a) Litter enclosed in fine mesh bags decomposed to some 40-44% of the initial amount placed in each of the three forests. Most of this decomposition can be attributed to abiotic factors and microoganisms. b) Litter placed in medium mesh litter bags reduced by ca. 60% in alluvial forest, ca. 50% in beech forest and ca. 44% in spruce forest. c) Litter enclosed in coarse mesh litter bags was reduced by 71% of the initial weights exposed in alluvial and beech forests; in the spruce forest decomposition was no greater than observed with fine and medium mesh litter bags. Clearly, in spruce forest the macrofauna has little or no part to play in effecting decomposition. 2. Sequential month by month exposure of hazel leaves and cellulose hydrate foil in coarse mesh litter bags in all three forests showed that one month of exposure led to only slight material losses, they did occur smallest between March and May, and largest between June and October/November. 3. Coarse mesh litter bags containing either hazel or artificial leaves of cellulose hydrate foil were exposed to natural decomposition processes in December 1977 and subsampled monthly over a period of one year, this series constituted the From-sequence of experiments. Each of the From-sequence samples removed was immediately replaced by a fresh litter bag which was left in place until December 1978, this series constituted the To-sequence of experiments. The results arising from the designated From- and To-sequences showed: a) During the course of one year hazel leaves decomposed completely in alluvial forest, almost completely in beech forest but to only 50% of the initial value in spruce forest. b) Duration of exposure and not the date of exposure is the major controlling influence on decomposition in alluvial forest, a characteristic reflected in the mirror-image courses of the From- and To-sequences curves with respect to the abscissa or time axis. Conversely the date of exposure and not the duration of exposure is the major controlling influence on decomposition in the spruce forest, a characteristic reflected in the mirror-image courses of the From-and To-sequences with respect to the ordinate or axis of percentage decomposition. c) Leaf powder amendment increased the decomposition rate of the hazel and cellulose hydrate leaves in the spruce forest but had no significant effect on their decomposition rate in alluvial and beech forests. It is concluded from this, and other evidence, that litter amendment by leaf fragments of phytophage frass in sites of low biological decomposition activity (eg. spruce) enhances decomposition processes. d) The time course of hazel leaf decomposition in both alluvial and beech forest is sigmoidal. Three s-phases are distinguished and correspond to the activity of microflora/microfauna, mesofauna/macrofauna, and then microflora/microfauna again. In general, the sigmoidal pattern of the curve can be considered valid for all decomposition processes occurring in terrestrial situations. It is contended that no decomposition (=disappearance) curve actually follows an e-type exponential function. A logarithmic linear regression can be constructed from the sigmoid curve data and although this facilitates inter-system comparisons it does not clearly express the dynamics of decomposition. 4. The course of the curve constructed from information about the standard deviations of means derived from the From- and To-sequence data does reflect the dynamics of litter decomposition. The three s-phases can be recognised and by comparing the actual From-sequence deviation curve with a mirror inversion representation of the To-sequence curve it is possible to determine whether decomposition is primarily controlled by the duration of exposure or the date of exposure. As is the case for hazel leaf decomposition in beech forest intermediate conditions can be readily recognised.

Nitrogen immobilization by decomposing woody debris and the recovery of tropical wet forest from hurricane disturbance

Treesearch

Jess K. Zimmerman; William M. Pulliam; D. Jean Lodge; Vanessa Quinones-Orfila; Ned Fetcher; Sandra Guzman-Grajales; John A. Parrotta; Clyde E. Asbury; Lars R. Walker; Robert B. Waide

1995-01-01

Following damage caused by Hurricane Hugo (September 1989) we monitored inorga­nic nitrogen availability in soil twice in 1990, leaf area index in 1991 and 1993, and litter production from 1990 through 1992 in subtropical wet forest of eastem Puerto Rico. Experimental removal of litter and woody debris generated by the hurricane (plus any standing stocks present before...

Response of reptile and amphibian communities to canopy gaps created by wind disturbance in the Southern Appalachians

Treesearch

Cathryn H. Greenberg

2001-01-01

Reptile and amphibian communities were sampled in intact gaps created by wind disturbance, salvage-logged gaps, and closed canopy mature forest (controls). Sampling was conducted during June–October in 1997 and 1998 using drift fences with pitfall and funnel traps. Basal area of live trees, shade, leaf litter coverage, and litter depth was highest in controls and...

Chronic nitrogen deposition influences the chemical dynamics ...

EPA Pesticide Factsheets

Atmospheric nitrogen deposition induces a forest carbon sink across broad parts of the Northern Hemisphere; this carbon sink may partly result from slower litter decomposition. Although microbial responses to experimental nitrogen deposition have been well-studied, evidence linking these microbial responses to changes in the degradation of specific compounds in decaying litter is sparse. We used wet chemistry and Fourier transform infrared spectroscopy (FTIR) methodologies to study the effects of chronic simulated nitrogen deposition on leaf litter and fine root chemistry during a three-year decomposition experiment at four northern hardwood forests in the north-central USA. Leaf litter and fine roots were highly different in initial chemistry such as concentrations of acid-insoluble fraction (AIF, or Klason lignin) and condensed tannins (CTs). These initial differences persisted over the course of decomposition. Results from gravimetrically-defined AIF and lignin/carbohydrate reference IR peak ratios both provide evidence that lignin in fine roots was selectively preserved under simulated nitrogen deposition. Lignin/carbohydrate peak ratios were strongly correlated with AIF, suggesting that AIF is a good predictor of lignin. Because AIF is abundant in fine roots, slower AIF degradation was the major driver of the slower fine root decomposition under nitrogen enrichment, explaining 73.9 % of the additional root mass retention. Nitrogen enrichment also slowed the

[Litter decomposition and lignocellulose enzyme activities of Actinothuidium hookeri and Cys- topteris montana in alpine timberline ecotone of western Sichuan, China].

PubMed

Chen, Ya-mei; He, Run-lian; Deng, Chang-chun; Yang, Wan-qin; Zhang, Jian; Yang, Lin; Liu, Yang

2015-11-01

The mass loss and lignocellulose enzyme activities of Actinothuidium hookeri residues and Cystopteris montana leaf litter in coniferous forest and timberline of western Sichuan, China were investigated. The results showed that both the mass loss rates of A. hookeri and C. Montana in timberline were higher than those in coniferous forest, while enzyme activities in timberline were lower than those in coniferous forest which was contrast with the hypothesis. The mass loss of two ground covers had significant differences in different seasons. The mass loss rate of A. hookeri in snow-covered season accounted for 69.8% and 83.0% of the whole year' s in timberline and coniferous forest, while that of C. montana in the growing season accounted for 82.6% and 83.4% of the whole year' s in timberline and coniferous forest, respectively. C. montana leaf litter decayed faster in the growing season, which was consistent with its higher cellulase activity in the growing season. The result illustrated that the enzymatic hydrolysis of cellulose and hemicellulose might be the main driving force for the early stage of litter decomposition. Multiple linear regression analysis showed that environmental factors and initial litter quality could explain 45.8%-85.1% variation of enzyme activity. The enzyme activities of A. hookeri and C. montana in the process of decomposition were mainly affected by the freeze-thaw cycle in snow-covered season.

Carbon and nitrogen loss during initial erosion processes under litter cover

NASA Astrophysics Data System (ADS)

Seitz, Steffen; Goebes, Philipp; Kühn, Peter; Scholten, Thomas

2013-04-01

Soil erosion translocates carbon (C) and nitrogen (N) from the soil pool. In natural or near-natural ecosystems like forests the soil is usually covered by litter. It can be assumed that litter decomposition and dust particles adhered on the surface of the leaves contribute to C and N fluxes during erosion processes as well. To our knowledge, the contribution of these compartments to the C and N balance of soil erosion is not yet known. As part of the "New Integrated Litter Experiment" within the DFG research unit "Biodiversity and Ecosystem Functioning (BEF)-China" we conducted a rainfall simulation experiment to quantify the role of litter cover for C and N fluxes during soil erosion in subtropical China. 96 mini runoff plots (40cm x 40cm) were established and divided into four blocks, two of them replicates. Seven different domestic litter species were used in this study combined to 1-species, 2-species and 4-species mixtures and complemented by none species plots (bare ground). Erosion processes were initiated by artificial rainfall using a rainfall simulator with a continuous and stable intensity of 60 mm/h. Sediment discharge and runoff volume were measured every 5 minutes for 20 minutes of rainfall duration and filtrated in the laboratory. Two time steps of rainfall simulation were carried out (summer 2012 and autumn 2012). Total C and N content were quantified from the solid sediment and the liquid runoff volume. Leaf decomposition rates were calculated based on the mass, leaf litter coverage was measured and loss of C and N contents from the decomposing leaves were provided by other project members. Additionally, C and N content of corresponding soils were designated. Lab work and statistical analysis are still ongoing. First results show that C and N concentrations of runoff and sediment are slightly higher for plots covered by litter than bare plots during the first run in summer 2012. It seems that 4-species plots have the highest C and N flux during rainfall simulation. Further analysis will focus on the role of litter diversity on C and N concentration and fluxes during initial erosion processes.

Intensification of freeze-thaw cycles in the soil on post-fire alpine slopes of Mount Shirouma-dake, northern Japanese Alps central Japan

NASA Astrophysics Data System (ADS)

Sasaki, A.; Suzuki, K.

2016-12-01

This is the continuous study to clarify the geo-environmental changes on the post-fire alpine slopes of Mount Shirouma-dake in the Northern Japanese Alps. The fire occurred at May 9, 2009 on the alpine slopes of Mount Shirouma-dake, and the fire spread to the Pinus pumila communities and grasslands. Although the grass had a little damage by the fire, the P. pumila received nearly impact of the fire. In the P. pumila communities where the leaf burnt, forest floor is exposed and become easy to be affected by atmospheric condition such as rain, wind, snow, and etc. First, we observed condition of the micro-landforms on post-fire slopes repeatedly for seventh years after the fire. As the results of the observation, it is clear that remarkable changes of these micro-landforms have not occurred but some litters on the forest-floor in the fired P. pumila communities are flushed out to surroundings. The litter layer on the forest-floor in the fired P. pumila communities were 3-4 cm thick in August of 2011, but it became 0.5 cm thick in September of 2014. The P. pumila communities established on the slopes consists of angular and sub-angular gravel with openwork texture, which are covered by thin soil layer. On July of 2016, the litter layer almost entirely flushed out and surface of soil layer is exposed to atmosphere. In addition, we observe the ground temperature and soil moisture, under the fired P. pumila communities and the no fired P. pumila communities since October 2009, to find influence of the fire. The ground temperature sensors were installed into at 1 cm, 10 cm, and 40 cm depth. The soil moisture sensors were installed into at 1 cm and 10 cm depth. The 1 cm depth of the soil on the post-fire slopes, several times of diurnal freeze-thaw cycles occurred on October and November since 2011, but it had not occurred in 2009 and 2010. In particular, more than 20 times of diurnal freeze-thaw cycles occurred on freezing period of 2014. The diurnal freeze-thaw cycles continue to be increasing until thawing period of 2016. The period of seasonal frost at 10 cm and 40 cm depth on the post-fire slopes are extended for two weeks. Snowmelt water is especially thought to be act on re-freezing of post-fire slopes on thawing period. These thermal condition changes are triggered by decrease in the thickness of the litter layer on the fired P. pumila communities.

Larval microhabitats of Lutzomyia longipalpis (Diptera: Psychodidae) in an endemic focus of visceral leishmaniasis in Colombia.

PubMed

Ferro, C; Pardo, R; Torres, M; Morrison, A C

1997-11-01

An intensive search for the larval habitats of Lutzomyia longipalpis (Lutz & Neiva) was conducted from November 1992 to October 1993 at a small rural community in Colombia where American visceral leishmaniasis is endemic. Emergence traps constructed from polyvinyl chloride pipes were used to sample a variety of soil microhabitats that included edge areas of covered pigpens, cattle corrals, the base of trees, and leaf litter at sites within 40 m of a house, rocks in fields located between 50 and 500 m from houses, and sites within a patch of secondary forest (rocks, base of palm trees, and leaf litter). The teneral status of the sand flies captured in the emergence traps was confirmed by laboratory studies that determined the rate of terminalia rotation in male L. longipalpis and the rate of cuticular growth layer formation of the thoracic phragma in both sexes of this species. A total of 58 teneral sand flies was captured during the study period (49 wk). Fifteen specimens were L. longipalpis; of these 11 (5 sand flies per square meter) were captured near pigpens, 3 (1.4 sand flies per square meter) were captured near rock resting sites, and 1 (1.6 sand flies per square meter) was collected at the base of a tree. The remainder of the sand flies were either L. trinidadensis (Newstead) or L. cayennensis (Flock & Abonnenc). Our results indicate that L. longipalpis larvae were dispersed widely in sites near houses, rather than concentrated in a few optimal microhabitats.

Influences of travertine dam formation on leaf litter decomposition and algal accrual

Treesearch

Codey D. Carter; Jane C. Marks

2007-01-01

At the time of this study Fossil Creek was being considered as a site for the restoration of a native fish assemblage, however there was concern amongst fisheries managers about the stream being food limited due to calcium carbonate (travertine) deposition. To evaluate the effects of travertine deposition on the aquatic food base we used leaf litterbags to compare...

Effects of Fungicides on Aquatic Fungi and Bacteria

NASA Astrophysics Data System (ADS)

Conners, D. E.; Rosemond, A. D.; Black, M. C.

2005-05-01

Aquatic microorganisms play an important role in conditioning leaf litter that enters streams and serves as an important base of production for consumers. Contamination of streams by fungicides may adversely affect microorganisms and alter leaf litter processing rates. Unfortunately, microorganisms are rarely used in acute toxicity tests for fungicide evaluation and registration. We adapted the resazurin reduction assay, which is used in medical microbiology, to assess the acute toxicity of four fungicides (azoxystrobin, trifloxystrobin, kresoxim-methyl and chlorothalonil) to aquatic fungi (Articulospora tetracladia) and bacteria (Cytophaga spp.), and investigated the ability of the toxicants to inhibit leaf breakdown in microcosms. Fungi were more sensitive to fungicides than many standard test organisms (cladocerans, green algae, trout), while bacteria were often the least sensitive. All of the fungicides except kresoxim-methyl, when added to microcosms at concentrations that inhibited the fungi by 90 percent in acute tests, reduced leaf breakdown rates by an average of 14.7 percent. Thus, aquatic fungi and their associated functions in streams may be relatively sensitive to fungicides applied terrestrially that enter streams through non-point sources. These data highlight the importance of including aquatic fungi in safety assessments of pesticides for protection of microbial function.

Isotopic characteristics of canopies in simulated leaf assemblages

NASA Astrophysics Data System (ADS)

Graham, Heather V.; Patzkowsky, Mark E.; Wing, Scott L.; Parker, Geoffrey G.; Fogel, Marilyn L.; Freeman, Katherine H.

2014-11-01

The geologic history of closed-canopy forests is of great interest to paleoecologists and paleoclimatologists alike. Closed canopies have pronounced effects on local, continental and global rainfall and temperature patterns. Although evidence for canopy closure is difficult to reconstruct from the fossil record, the characteristic isotope gradients of the ;canopy effect; could be preserved in leaves and proxy biomarkers. To assess this, we employed new carbon isotopic data for leaves collected in diverse light environments within a deciduous, temperate forest (Maryland, USA) and for leaves from a perennially closed canopy, moist tropical forest (Bosque Protector San Lorenzo, Panamá). In the tropical forest, leaf carbon isotope values range 10‰, with higher δ13Cleaf values occurring both in upper reaches of the canopy, and with higher light exposure and lower humidity. Leaf fractionation (Δleaf) varied negatively with height and light and positively with humidity. Vertical 13C enrichment in leaves largely reflects changes in Δleaf, and does not trend with δ13C of CO2 within the canopy. At the site in Maryland, leaves express a more modest δ13C range (∼6‰), with a clear trend that follows both light and leaf height. Using a model we simulate leaf assemblage isotope patterns from canopy data binned by elevation. The re-sampling (bootstrap) model determined both the mean and range of carbon isotope values for simulated leaf assemblages ranging in size from 10 to over 1000 leaves. For the tropical forest data, the canopy's isotope range is captured with 50 or more randomly sampled leaves. Thus, with a sufficient number of fossil leaves it is possible to distinguish isotopic gradients in an ancient closed canopy forest from those in an open forest. For very large leaf assemblages, mean isotopic values approximate the δ13C of carbon contributed by leaves to soil and are similar to observed δ13Clitter values at forested sites within Panamá, including the site where leaves were sampled. The model predicts a persistent ∼1‰ difference in δ13Clitter for the two sites which is consistent with higher water availability in the tropical forests. This work provides a new framework for linking contemporary ecological observations to the geochemical record using flux-weighted isotope data and lends insights to the effect of forest architecture on organic and isotopic records of ancient terrestrial ecosystems. How many leaves from a litter assemblage are necessary to distinguish the isotopic gradient characteristics of canopy closure? Are mean δ13Cleaf values for a litter assemblage diagnostic of a forest biome? Can we predict the δ13C values of cumulative litter, soil organic matter, and organic carbon in sedimentary archives using litter flux and isotope patterns in canopies? We determined the δ13C range and mean for different sized assemblages of leaves sampled from data for each forest. We re-sampled very high numbers of leaves in order to estimate the isotopic composition of cumulative carbon delivered to soils as litter, and compared these results to available data from forest soils. Modeled leaf and soil organic carbon isotope patterns in this study offer insights to how forest structure can be derived from carbon isotope measurements of fossil leaves, as well as secondary material - such as teeth, hair, paleosol carbonates, or organic soil carbon (van der Merwe and Medina, 1989; Koch, 1998; Secord et al., 2008; Levin et al., 2011).Distinct climate and seasonal difference in the Panamá and Maryland, USA forests are reflected in their canopy isotope gradients. In the tropical forest of Panamá, leaves are produced throughout the year within a canopy that is both extensively and persistently closed (Leigh, 1975; Lowman and Wittman, 1996). In the temperate forest of Maryland leaves are produced during the spring when canopy conditions are relatively open (Korner and Basler, 2010).

Interspecific variations in mangrove leaf litter decomposition are related to labile nitrogenous compounds

NASA Astrophysics Data System (ADS)

Nordhaus, Inga; Salewski, Tabea; Jennerjahn, Tim C.

2017-06-01

Mangrove leaves form a large pool of carbon, nitrogen and energy that is a major driver of element cycles and detrital food webs inside mangrove forests as well as in adjacent coastal waters. However, there are large gaps in knowledge on the transformation pathways and ultimate fate of leaf nitrogen. Therefore, the main objective of this study was to determine the amount and composition of nitrogenous organic matter and possible species-specific differences during the decomposition of mangrove leaf litter. For that purpose a three month decomposition experiment with litterbags was conducted using leaves of Aegiceras corniculatum, Avicennia alba, Ceriops decandra, Rhizophora apiculata, and Sonneratia caseolaris in the mangrove forest of the Segara Anakan Lagoon, Java, Indonesia. Detrital leaves were analyzed for bulk carbon and total nitrogen (N), stable carbon and nitrogen isotope composition (δ13C, δ15N), total hydrolyzable amino acids (THAA) and total hydrolyzable hexosamines (THHA). Decomposition rates (k d-1) were highest and tM50 values (when 50% of the original mass had been degraded) lowest in S. caseolaris (k = 0.0382 d-1; tM50 = 18 days), followed by A. alba, C. decandra, A. corniculatum, and R. apiculata (k = 0.0098 d-1; tM50 = 71 days). The biochemical composition of detrital leaves differed significantly among species and over time. S. caseolaris and A. alba had higher concentrations of N, THAA and THHA and a lower C/N ratio than the other three species. For most of the species concentrations of N, THAA and THHA increased during decomposition. The hexosamine galactosamine, indicative of bacterial cell walls, was first found in leaves after 5-7 days of decomposition and increased afterwards. Our findings suggest an increasing, but species-specific varying, portion of labile nitrogenous OM and total N in decomposing leaves over time that is partly related to the activity of leaf-colonizing bacteria. Despite a higher relative nitrogen content in the remaining litter of the fast decomposing S. caseolaris and A. alba as compared to the other three species, the total loss of nitrogen was even higher because of the much higher mass loss after three months of decomposition. It is inferred that the amount of labile nitrogenous organic matter plays a major role in determining the rate of decomposition of leaf litter in mangroves.

From leaf longevity to canopy seasonality: a carbon optimality phenology model for tropical evergreen forests

NASA Astrophysics Data System (ADS)

Xu, X.; Medvigy, D.; Wu, J.; Wright, S. J.; Kitajima, K.; Pacala, S. W.

2016-12-01

Tropical evergreen forests play a key role in the global carbon, water and energy cycles. Despite apparent evergreenness, this biome shows strong seasonality in leaf litter and photosynthesis. Recent studies have suggested that this seasonality is not directly related to environmental variability but is dominated by seasonal changes of leaf development and senescence. Meanwhile, current terrestrial biosphere models (TBMs) can not capture this pattern because leaf life cycle is highly underrepresented. One challenge to model this leaf life cycle is the remarkable diversity in leaf longevity, ranging from several weeks to multiple years. Ecologists have proposed models where leaf longevity is regarded as a strategy to optimize carbon gain. However previous optimality models can not be readily integrated into TBMs because (i) there are still large biases in predicted leaf longevity and (ii) it is never tested whether the carbon optimality model can capture the observed seasonality in leaf demography and canopy photosynthesis. In this study, we develop a new carbon optimality model for leaf demography. The novelty of our approach is two-fold. First, we incorporate a mechanistic photosynthesis model that can better estimate leaf carbon gain. Second, we consider the interspecific variations in leaf senescence rate, which strongly influence the modelled optimal carbon gain. We test our model with a leaf trait database for Panamanian evergreen forests. Then, we apply the model at seasonal scale and compare simulated seasonality of leaf litter and canopy photosynthesis with in-situ observations from several Amazonian forest sites. We find that (i) compared with original optimality model, the regression slope between observed and predicted leaf longevity increases from 0.15 to 1.04 in our new model and (ii) that our new model can capture the observed seasonal variations of leaf demography and canopy photosynthesis. Our results suggest that the phenology in tropical evergreen forests might result from plant adaptation to optimize canopy carbon gain. Finally, this proposed trait-driven prognostic phenology model could potentially be incorporated into next generation TBMs to improve simulation of carbon and water fluxes in the tropics.

Flower litters of alpine plants affect soil nitrogen and phosphorus rapidly in the eastern Tibetan Plateau

NASA Astrophysics Data System (ADS)

Wang, Jinniu; Xu, Bo; Wu, Yan; Gao, Jing; Shi, Fusun

2016-10-01

Litters of reproductive organs have rarely been studied despite their role in allocating nutrients for offspring reproduction. This study determines the mechanism through which flower litters efficiently increase the available soil nutrient pool. Field experiments were conducted to collect plant litters and calculate biomass production in an alpine meadow of the eastern Tibetan Plateau. C, N, P, lignin, cellulose content, and their relevant ratios of litters were analyzed to identify their decomposition features. A pot experiment was performed to determine the effects of litter addition on the soil nutrition pool by comparing the treated and control samples. The litter-bag method was used to verify decomposition rates. The flower litters of phanerophyte plants were comparable with non-flower litters. Biomass partitioning of other herbaceous species accounted for 10-40 % of the aboveground biomass. Flower litter possessed significantly higher N and P levels but less C / N, N / P, lignin / N, and lignin and cellulose concentrations than leaf litter. The litter-bag experiment confirmed that the flower litters of Rhododendron przewalskii and Meconopsis integrifolia decompose approximately 3 times faster than mixed litters within 50 days. Pot experiment findings indicated that flower litter addition significantly increased the available nutrient pool and soil microbial productivity. The time of litter fall significantly influenced soil available N and P, and soil microbial biomass. Flower litters fed the soil nutrition pool and influenced nutrition cycling in alpine ecosystems more efficiently because of their non-ignorable production, faster decomposition rate, and higher nutrient contents compared with non-flower litters. The underlying mechanism can enrich nutrients, which return to the soil, and non-structural carbohydrates, which feed and enhance the transitions of soil microorganisms.

Identification and Phytotoxicity Assessment of Phenolic Compounds in Chrysanthemoides monilifera subsp. monilifera (Boneseed).

PubMed

Al Harun, Md Abdullah Yousuf; Johnson, Joshua; Uddin, Md Nazim; Robinson, Randall W

2015-01-01

Chrysanthemoides monilifera subsp. monilifera (boneseed), a weed of national significance in Australia, threatens indigenous species and crop production through allelopathy. We aimed to identify phenolic compounds produced by boneseed and to assess their phytotoxicity on native species. Phenolic compounds in water and methanol extracts, and in decomposed litter-mediated soil leachate were identified using HPLC, and phytotoxicity of identified phenolics was assessed (repeatedly) through a standard germination bioassay on native Isotoma axillaris. The impact of boneseed litter on native Xerochrysum bracteatum was evaluated using field soil in a greenhouse. Collectively, we found the highest quantity of phenolic compounds in boneseed litter followed by leaf, root and stem. Quantity varied with extraction media. The rank of phenolics concentration in boneseed was in the order of ferulic acid > phloridzin > catechin > p-coumaric acid and they inhibited germination of I. axillaris with the rank of ferulic acid > catechin > phloridzin > p-coumaric acid. Synergistic effects were more severe compared to individual phenolics. The litter-mediated soil leachate (collected after15 days) exhibited strong phytotoxicity to I. axillaris despite the level of phenolic compounds in the decomposed leachate being decreased significantly compared with their initial level. This suggests the presence of other unidentified allelochemicals that individually or synergistically contributed to the phytotoxicity. Further, the dose response phytotoxic impacts exhibited by the boneseed litter-mediated soil to native X. bracteatum in a more naturalistic greenhouse experiment might ensure the potential allelopathy of other chemical compounds in the boneseed invasion. The reduction of leaf relative water content and chlorophyll level in X. bracteatum suggest possible mechanisms underpinning plant growth inhibition caused by boneseed litter allelopathy. The presence of a substantial quantity of free proline in the target species also suggests that the plant was in a stressed condition due to litter allelopathy. These findings are important for better understanding the invasive potential of boneseed and in devising control strategies.

Identification and Phytotoxicity Assessment of Phenolic Compounds in Chrysanthemoides monilifera subsp. monilifera (Boneseed)

PubMed Central

Al Harun, Md Abdullah Yousuf; Johnson, Joshua; Uddin, Md Nazim; Robinson, Randall W.

2015-01-01

Chrysanthemoides monilifera subsp. monilifera (boneseed), a weed of national significance in Australia, threatens indigenous species and crop production through allelopathy. We aimed to identify phenolic compounds produced by boneseed and to assess their phytotoxicity on native species. Phenolic compounds in water and methanol extracts, and in decomposed litter-mediated soil leachate were identified using HPLC, and phytotoxicity of identified phenolics was assessed (repeatedly) through a standard germination bioassay on native Isotoma axillaris. The impact of boneseed litter on native Xerochrysum bracteatum was evaluated using field soil in a greenhouse. Collectively, we found the highest quantity of phenolic compounds in boneseed litter followed by leaf, root and stem. Quantity varied with extraction media. The rank of phenolics concentration in boneseed was in the order of ferulic acid > phloridzin > catechin > p-coumaric acid and they inhibited germination of I. axillaris with the rank of ferulic acid > catechin > phloridzin > p-coumaric acid. Synergistic effects were more severe compared to individual phenolics. The litter-mediated soil leachate (collected after15 days) exhibited strong phytotoxicity to I. axillaris despite the level of phenolic compounds in the decomposed leachate being decreased significantly compared with their initial level. This suggests the presence of other unidentified allelochemicals that individually or synergistically contributed to the phytotoxicity. Further, the dose response phytotoxic impacts exhibited by the boneseed litter-mediated soil to native X. bracteatum in a more naturalistic greenhouse experiment might ensure the potential allelopathy of other chemical compounds in the boneseed invasion. The reduction of leaf relative water content and chlorophyll level in X. bracteatum suggest possible mechanisms underpinning plant growth inhibition caused by boneseed litter allelopathy. The presence of a substantial quantity of free proline in the target species also suggests that the plant was in a stressed condition due to litter allelopathy. These findings are important for better understanding the invasive potential of boneseed and in devising control strategies. PMID:26465595

Research on spatial distribution of photosynthetic characteristics of Winter Wheat

NASA Astrophysics Data System (ADS)

Yan, Q. Q.; Zhou, Q. Y.; Zhang, B. Z.; Han, X.; Han, N. N.; Li, S. M.

2018-03-01

In order to explore the spatial distribution of photosynthetic characteristics of winter wheat leaf, the photosynthetic rate on different parts of leaf (leaf base-leaf middle-leaf apex) and that on each canopy (top layer-middle layer-bottom layer) leaf during the whole growth period of winter wheat were measured. The variation of photosynthetic rate with PAR and the spatial distribution of winter wheat leaf during the whole growth periods were analysed. The results showed that the photosynthetic rate of different parts of winter wheat increased with the increase of PAR, which was showed as leaf base>leaf middle>leaf apex. In the same growth period, photosynthetic rate in different parts of the tablet was showed as leaf middle>leaf base>leaf apex. For the different canopy layer of winter wheat, the photosynthetic rate of the top layer leaf was significantly greater than that of the middle layer and lower layer leaf. The photosynthetic rate of the top layer leaf was the largest in the leaf base position. The photosynthetic rate of leaf of the same canopy layer at different growth stages were showed as tasseling stage >grain filling stage > maturation stage.

General and specific gypsy moth predators

Treesearch

Ronald M. Weseloh

1991-01-01

General larval predators of low-density gypsy moth, Lymantria dispar (L.), populations have been assessed by exposing caterpillars tethered by threads. Most mortality occurred on tree trunks and in leaf litter.

Antibiotic mixture effects on growth of the leaf-shredding stream detritivore Gammarus fossarum.

PubMed

Bundschuh, Mirco; Hahn, Torsten; Gessner, Mark O; Schulz, Ralf

2017-05-01

Pharmaceuticals contribute greatly to human and animal health. Given their specific biological targets, pharmaceuticals pose a significant environmental risk by affecting organisms and ecosystem processes, including leaf-litter decomposition. Although litter decomposition is a central process in forest streams, the consequences of exposure to pharmaceuticals remain poorly known. The present study assessed the impact of antibiotics as an important class of pharmaceuticals on the growth of the leaf-shredding amphipod Gammarus fossarum over 24 days. Exposure scenarios involved an antibiotic mixture (i.e. sulfamethoxazole, trimethoprim, erythromycin-H 2 O, roxithromycin, clarithromycin) at 0, 2 and 200 µg/L to assess impacts resulting from exposure to both water and food. The antibiotics had no effect on either leaf-associated fungal biomass or bacterial abundance. However, modification of leaf quality (e.g. through shifts in leaf-associated microbial communities) may have triggered faster growth of gammarids (assessed in terms of body mass gain) at the low antibiotic concentration relative to the control. At 200 µg/L, however, gammarid growth was not stimulated. This outcome might be due to a modified ability of the gut microflora to assimilate nutrients and carbon. Furthermore, the observed lack of increases in the diameter of the gammarids' peduncles, despite an increase in gammarid mass, suggests antibiotic-induced effects in the moulting cycle. Although the processes responsible for the observed effects have not yet been identified, these results suggest a potential role of food-quality, gammarid gut microflora and alteration in the moulting cycle in mediating impacts of antibiotics on these detritivores and the leaf decomposition process in streams.

Alteration of Microbial Communities Colonizing Leaf Litter in a Temperate Woodland Stream by Growth of Trees under Conditions of Elevated Atmospheric CO2 ▿

PubMed Central

Kelly, John J.; Bansal, Amit; Winkelman, Jonathan; Janus, Lori R.; Hell, Shannon; Wencel, Marie; Belt, Patricia; Kuehn, Kevin A.; Rier, Steven T.; Tuchman, Nancy C.

2010-01-01

Elevated atmospheric CO2 can cause increased carbon fixation and altered foliar chemical composition in a variety of plants, which has the potential to impact forested headwater streams because they are detritus-based ecosystems that rely on leaf litter as their primary source of organic carbon. Fungi and bacteria play key roles in the entry of terrestrial carbon into aquatic food webs, as they decompose leaf litter and serve as a source of nutrition for invertebrate consumers. This study tested the hypothesis that changes in leaf chemistry caused by elevated atmospheric CO2 would result in changes in the size and composition of microbial communities colonizing leaves in a woodland stream. Three tree species, Populus tremuloides, Salix alba, and Acer saccharum, were grown under ambient (360 ppm) or elevated (720 ppm) CO2, and their leaves were incubated in a woodland stream. Elevated-CO2 treatment resulted in significant increases in the phenolic and tannin contents and C/N ratios of leaves. Microbial effects, which occurred only for P. tremuloides leaves, included decreased fungal biomass and decreased bacterial counts. Analysis of fungal and bacterial communities on P. tremuloides leaves via terminal restriction fragment length polymorphism (T-RFLP) and clone library sequencing revealed that fungal community composition was mostly unchanged by the elevated-CO2 treatment, whereas bacterial communities showed a significant shift in composition and a significant increase in diversity. Specific changes in bacterial communities included increased numbers of alphaproteobacterial and cytophaga-flavobacter-bacteroides (CFB) group sequences and decreased numbers of betaproteobacterial and firmicutes sequences, as well as a pronounced decrease in overall Gram-positive bacterial sequences. PMID:20543045

Alteration of microbial communities colonizing leaf litter in a temperate woodland stream by growth of trees under conditions of elevated atmospheric CO2.

PubMed

Kelly, John J; Bansal, Amit; Winkelman, Jonathan; Janus, Lori R; Hell, Shannon; Wencel, Marie; Belt, Patricia; Kuehn, Kevin A; Rier, Steven T; Tuchman, Nancy C

2010-08-01

Elevated atmospheric CO(2) can cause increased carbon fixation and altered foliar chemical composition in a variety of plants, which has the potential to impact forested headwater streams because they are detritus-based ecosystems that rely on leaf litter as their primary source of organic carbon. Fungi and bacteria play key roles in the entry of terrestrial carbon into aquatic food webs, as they decompose leaf litter and serve as a source of nutrition for invertebrate consumers. This study tested the hypothesis that changes in leaf chemistry caused by elevated atmospheric CO(2) would result in changes in the size and composition of microbial communities colonizing leaves in a woodland stream. Three tree species, Populus tremuloides, Salix alba, and Acer saccharum, were grown under ambient (360 ppm) or elevated (720 ppm) CO(2), and their leaves were incubated in a woodland stream. Elevated-CO(2) treatment resulted in significant increases in the phenolic and tannin contents and C/N ratios of leaves. Microbial effects, which occurred only for P. tremuloides leaves, included decreased fungal biomass and decreased bacterial counts. Analysis of fungal and bacterial communities on P. tremuloides leaves via terminal restriction fragment length polymorphism (T-RFLP) and clone library sequencing revealed that fungal community composition was mostly unchanged by the elevated-CO(2) treatment, whereas bacterial communities showed a significant shift in composition and a significant increase in diversity. Specific changes in bacterial communities included increased numbers of alphaproteobacterial and cytophaga-flavobacter-bacteroides (CFB) group sequences and decreased numbers of betaproteobacterial and firmicutes sequences, as well as a pronounced decrease in overall gram-positive bacterial sequences.

Characteristics and DBP formation of dissolved organic matter from leachates of fresh and aged leaf litter.

PubMed

Jian, Qianyun; Boyer, Treavor H; Yang, Xiuhong; Xia, Beicheng; Yang, Xin

2016-06-01

Dissolved organic matter (DOM) was leached from leaves of two trees commonly grown in subtropical regions, Pinus elliottii (commonly known as slash pine) and Schima superba (S. superba), and its degradation pattern and potential for forming disinfection byproducts (DBPs) were evaluated. The leaves were exposed in the field for up to one year before leaching. The DOM leached from slash pine litter contained on average 10.4 mg of dissolved organic carbon (DOC) per gram of dry weight; for S. superba the average was 37.2 mg-DOC/g-dry weight. Ultraviolet and visible light absorbance, fluorescence, and molecular weight analysis indicated that more aromatic/humic and higher molecular weight compounds are formed as leaf litter ages. A 4-component parallel factor analysis of the fluorescence data showed that the intensity of peaks related with protein-like components decreased gradually during biodegradation, while that of peaks attributed to humic-acid-like components increased continuously. Fresh slash pine leachates formed on average 40.0 μg of trihalomethane (THM) per milligram of DOC, while S. superba leachates formed 45.6 μg. THM formation showed peak values of 55.7 μg/mg DOC for slash pine and 74.9 μg/mg DOC for S. superba after 8 months of aging. The formation of haloacetonitrile (HAN) and trichloronitromethane (TCNM) increased with increasing leaf age, while chloral hydrate (CH) formation did not show such a trend. Specific UV absorbance showed some positive correlation with DBPs, but humic-acid-like and protein-like absorbance peaks correlated with CH and TCNM yields in only some leaf samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

Factors affecting the abundance of leaf-litter arthropods in unburned and thrice-burned seasonally-dry Amazonian forests.

PubMed

Silveira, Juliana M; Barlow, Jos; Louzada, Julio; Moutinho, Paulo

2010-09-21

Fire is frequently used as a land management tool for cattle ranching and annual crops in the Amazon. However, these maintenance fires often escape into surrounding forests, with potentially severe impacts for forest biodiversity. We examined the effect of experimental fires on leaf-litter arthropod abundance in a seasonally-dry forest in the Brazilian Amazon. The study plots (50 ha each) included a thrice-burned forest and an unburned control forest. Pitfall-trap samples were collected at 160 randomly selected points in both plots, with sampling stratified across four intra-annual replicates across the dry and wet seasons, corresponding to 6, 8, 10 and 12 months after the most recent fire. Arthropods were identified to the level of order (separating Formicidae). In order to better understand the processes that determine arthropod abundance in thrice-burned forests, we measured canopy openness, understory density and litter depth. All arthropod taxa were significantly affected by fire and season. In addition, the interactions between burn treatment and season were highly significant for all taxa but Isoptera. The burned plot was characterized by a more open canopy, lower understory density and shallower litter depth. Hierarchical partitioning revealed that canopy openness was the most important factor explaining arthropod order abundances in the thrice-burned plot, whereas all three environmental variables were significant in the unburned control plot. These results reveal the marked impact of recurrent wildfires and seasonality on litter arthropods in this transitional forest, and demonstrate the overwhelming importance of canopy-openness in driving post-fire arthropod abundance.

Factors Affecting the Abundance of Leaf-Litter Arthropods in Unburned and Thrice-Burned Seasonally-Dry Amazonian Forests

PubMed Central

Silveira, Juliana M.; Barlow, Jos; Louzada, Julio; Moutinho, Paulo

2010-01-01

Fire is frequently used as a land management tool for cattle ranching and annual crops in the Amazon. However, these maintenance fires often escape into surrounding forests, with potentially severe impacts for forest biodiversity. We examined the effect of experimental fires on leaf-litter arthropod abundance in a seasonally-dry forest in the Brazilian Amazon. The study plots (50 ha each) included a thrice-burned forest and an unburned control forest. Pitfall-trap samples were collected at 160 randomly selected points in both plots, with sampling stratified across four intra-annual replicates across the dry and wet seasons, corresponding to 6, 8, 10 and 12 months after the most recent fire. Arthropods were identified to the level of order (separating Formicidae). In order to better understand the processes that determine arthropod abundance in thrice-burned forests, we measured canopy openness, understory density and litter depth. All arthropod taxa were significantly affected by fire and season. In addition, the interactions between burn treatment and season were highly significant for all taxa but Isoptera. The burned plot was characterized by a more open canopy, lower understory density and shallower litter depth. Hierarchical partitioning revealed that canopy openness was the most important factor explaining arthropod order abundances in the thrice-burned plot, whereas all three environmental variables were significant in the unburned control plot. These results reveal the marked impact of recurrent wildfires and seasonality on litter arthropods in this transitional forest, and demonstrate the overwhelming importance of canopy-openness in driving post-fire arthropod abundance. PMID:20877720

Effect of temperature and moisture on the mineralization and humification of leaf litter in a model incubation experiment

NASA Astrophysics Data System (ADS)

Larionova, A. A.; Maltseva, A. N.; Lopes de Gerenyu, V. O.; Kvitkina, A. K.; Bykhovets, S. S.; Zolotareva, B. N.; Kudeyarov, V. N.

2017-04-01

The mineralization and humification of leaf litter collected in a mixed forest of the Prioksko-Terrasny Reserve depending on temperature (2, 12, and 22°C) and moisture (15, 30, 70, 100, and 150% of water holding capacity ( WHC)) has been studied in long-term incubation experiments. Mineralization is the most sensitive to temperature changes at the early stage of decomposition; the Q 10 value at the beginning of the experiment (1.5-2.7) is higher than at the later decomposition stages (0.3-1.3). Carbon losses usually exceed nitrogen losses during decomposition. Intensive nitrogen losses are observed only at the high temperature and moisture of litter (22°C and 100% WHC). Humification determined from the accumulation of humic substances in the end of incubation decreases from 34 to 9% with increasing moisture and temperature. The degree of humification CHA/CFA is maximum (1.14) at 12°C and 15% WHC; therefore, these temperature and moisture conditions are considered optimal for humification. Humification calculated from the limit value of litter mineralization is almost independent of temperature, but it significantly decreases from 70 to 3% with increasing moisture. A possible reason for the difference between the humification values measured by two methods is the conservation of a significant part of hemicelluloses, cellulose, and lignin during the transformation of litter and the formation of a complex of humic substances with plant residues, where HSs fulfill a protectoral role and decrease the decomposition rate of plant biopolymers.

Freshwater wrack along Great Lakes coasts harbors Escherichia coli: Potential for bacterial transfer between watershed environments

USGS Publications Warehouse

Nevers, Meredith; Przybyla-Kelly, Kasia; Spoljaric, Ashley; Shively, Dawn A.; Whitman, Richard L.; Byappanahalli, Muruleedhara

2016-01-01

We investigated the occurrence, persistence, and growth potential of Escherichia coli associated with freshwater organic debris (i.e., wrack) frequently deposited along shorelines (shoreline wrack), inputs from rivers (river CPOM), and parking lot runoffs (urban litter). Samples were collected from 9 Great Lakes beaches, 3 creeks, and 4 beach parking lots. Shoreline wrack samples were mainly composed of wood chips, straw, sticks, leaf litter, seeds, feathers, and mussel shells; creek and parking lot samples included dry grass, straw, seeds, wood chips, leaf/pine needle litter; soil particles were present in parking lot samples only. E. coli concentrations (most probable number, MPN) were highly variable in all sample types: shoreline wrack frequently reached 105/g dry weight (dw), river CPOM ranged from 81 to 7,916/g dw, and urban litter ranged from 0.5 to 24,952/g dw. Sequential rinsing studies showed that 61–87% of E. coli concentrations were detected in the first wash of shoreline wrack, with declining concentrations associated with 4–8 subsequent washings; viable counts were still detected even after 8 washes. E. coli grew readily in shoreline wrack and river CPOM incubated at 35 °C. At 30°C, growth was only detected in river CPOM and not in shoreline wrack or urban litter, but the bacteria persisted for at least 16 days. In summary, freshwater wrack is an understudied component of the beach ecosystem that harbors E. coli and thus likely influences estimations of water quality and the microbial community in the nearshore as a result of transfer between environments.

Changes in litter near an aluminum reduction plant

USGS Publications Warehouse

Beyer, W.N.; Fleming, W.J.; Swineford, D.

1987-01-01

Litter was collected from eight sites at distances as far as 33 km from an AI reduction plant in western Tennessee. As a result of an accumulation of fine litter (< 4.75 mm) the weight of the litter per unit area was abnormally high at the two sites within 2 km of the plant. Compared to litter collected far from the plant, it had a lower fiber content, was more sapric, and was less acid. Fluoride emissions from the plant were suggested as the probable cause of litter changes. Concentrations of water-extractable and acid-extractable F- in the litter, the 0- to 5-cm soil layer, and the 5- to 15-cm soil layer were strongly correlated with distance from the plant. Total acid-extractable F- in the litter and upper 15 cm of soil was about 41 times as much at the closest site (700 mg/kg) as at the most distant sites (12 and 16 mg/kg). In a bioassay of litter from our study sites, woodlice (Porcellio scaber Latr.) had an abnormally high mortality in litter that contained 440 mg/kg or more of acid-extractable F-. However, when F- was added as NaF to litter, a significant increase in mortality was observed only in treatments exceeding 800 mg/kg. The decrease in the rate of decomposition of the litter might eventually induce a deficiency of soil macronutrients, but none was detected.

Relationship of host recurrence in fungi to rates of tropical leaf decomposition

Treesearch

Mirna E. Santanaa; JeanD. Lodgeb; Patricia Lebowc

2004-01-01

Here we explore the significance of fungal diversity on ecosystem processes by testing whether microfungal ‘preferences’ for (i.e., host recurrence) different tropical leaf species increases the rate of decomposition. We used pairwise combinations of girradiated litter of five tree species with cultures of two dominant microfungi derived from each plant in a microcosm...

Ecophysiology of a Mangrove Forest in Jobos Bay, Puerto Rico

Treesearch

ARIEL E. LUGO; ERNESTO MEDINA; ELVIRA CUEVAs; CINTR& #211; GILBERTO N; EDDIE N. LABOY NIEVES; SCH& #196; YARA EFFER NOVELLI

2007-01-01

We studied gas exchange, leaf dimensions, litter production, leaf and litterfall chemistry, nutrient flux to the forest floor, retranslocation rates, and nutrient use efficiency of mangroves in Jobos Bay, Puerto Rico. The fringe forest had a salinity gradient from the ocean (35‰) to a salt flat (100‰) and a basin (about 80‰). Red (Rhizophora mangle), white (...

Relationship of host recurrence in fungi to rates of tropical leaf decomposition

Treesearch

Mirna E. Santana; D. Jean Lodge; Patricia Lebow

2005-01-01

Here we explore the significance of fungal diversity on ecosystem processes by testing whether microfungal ‘preferences’ for (i.e., host recurrence) different tropical leaf species increases the rate of decomposition. We used pairwise combinations of [gamma]-irradiated litter of five tree species with cultures of two dominant microfungi derived from each plant in a...

Soil biogeochemical and fungal patterns across a precipitation gradient in the lowland tropical rainforests of French Guiana

NASA Astrophysics Data System (ADS)

Soong, J.; Verbruggen, E.; Janssens, I.

2016-12-01

The Guyafor network contains over 12 pristine tropical rainforest long-term research sites throughout French Guiana, with a focus on vegetation and environmental monitoring at regular intervals. However, biogeochemical and belowground insights are needed to complete the picture of ecosystem functioning in these lowland tropical rainforests, which are critical to Earth's water and energy balance. Improving our biogeochemical understanding of these ecosystems is needed to improve Earth System Models, which poorly represent tropical systems. In July 2015 we sampled soils and litter from 12 of the Guyafor permanent plots in French Guiana spanning a mean annual precipitation gradient of over 2000 mm per year. We measured soil texture, pH, C, N and available P stocks in the top 30 cm, and fungal biodiversity using ITS DNA sequencing and characterized soil organic matter (SOM) C, N and P distribution among physically defined SOM fractions. We also measured litter layer standing stocks and CNP stoichiometry. We found significant stocks of SOM in the top 30 cm of the soil varying by a factor of 4 in the top 30 cm of soil with a negative correlation of arbuscular mycorrhizal fungi and soil C and N with available P. Available P was also a strong predictor of fungal community composition. Furthermore there is evidence for precipitation and mineralogical influences on leaf litter and SOM dynamics highlighting the importance of heterogeneity in tropical soil substrates and sub-climates in better understanding the biogeochemistry of tropical ecosystems.

Impact of Conifer Forest Litter on Microwave Emission at L-Band

NASA Technical Reports Server (NTRS)

Kurum, Mehmet; O'Neill, Peggy E.; Lang, Roger H.; Cosh, Michael H.; Joseph, Alicia T.; Jackson, Thomas J.

2011-01-01

This study reports on the utilization of microwave modeling, together with ground truth, and L-band (1.4-GHz) brightness temperatures to investigate the passive microwave characteristics of a conifer forest floor. The microwave data were acquired over a natural Virginia Pine forest in Maryland by a ground-based microwave active/passive instrument system in 2008/2009. Ground measurements of the tree biophysical parameters and forest floor characteristics were obtained during the field campaign. The test site consisted of medium-sized evergreen conifers with an average height of 12 m and average diameters at breast height of 12.6 cm. The site is a typical pine forest site in that there is a surface layer of loose debris/needles and an organic transition layer above the mineral soil. In an effort to characterize and model the impact of the surface litter layer, an experiment was conducted on a day with wet soil conditions, which involved removal of the surface litter layer from one half of the test site while keeping the other half undisturbed. The observations showed detectable decrease in emissivity for both polarizations after the surface litter layer was removed. A first-order radiative transfer model of the forest stands including the multilayer nature of the forest floor in conjunction with the ground truth data are used to compute forest emission. The model calculations reproduced the major features of the experimental data over the entire duration, which included the effects of surface litter and ground moisture content on overall emission. Both theory and experimental results confirm that the litter layer increases the observed canopy brightness temperature and obscure the soil emission.

Riparian litter inputs to streams in the central Oregon Coast Range

USGS Publications Warehouse

Hart, Stephanie K.; Hibbs, David E.; Perakis, Steven S.

2013-01-01

Riparian-zone vegetation can influence terrestrial and aquatic food webs through variation in the amount, timing, and nutritional content of leaf and other litter inputs. We investigated how riparian-forest community composition, understory density, and lateral slope shaped vertical and lateral litter inputs to 16 streams in the Oregon Coast Range. Riparian forests dominated by deciduous red alder delivered greater annual vertical litter inputs to streams (504 g m−2 y−1) than did riparian forests dominated by coniferous Douglas-fir (394 g m−2 y−1). Deciduous forests also contributed greater lateral litter inputs per meter of stream bank on one side (109 g m−1 y−1) than did coniferous forests (63 g m−1 y−1). Total litter inputs from deciduous forests exceeded those from coniferous forests most strongly in November, coincident with an autumn peak in litter inputs. Lateral litter inputs contributed most to total inputs during winter in both forest types. Annual lateral litter movement increased with slope at deciduous sites, but only in spring/summer months at coniferous sites. Neither experimental removal of understory vegetation nor installation of mesh fences to block downslope litter movement affected lateral litter inputs to streams, suggesting that ground litter moves <5 m downslope annually. N concentrations of several litter fractions were higher at deciduous sites and, when combined with greater litter amounts, yielded twice as much total litter N flux to streams in deciduous than coniferous sites. The presence of red alder in riparian forests along many small streams of the deeply incised and highly dendritic basins of the Oregon Coast Range enhances total fluxes and seasonality of litter delivery to both terrestrial and aquatic food webs in this region and complements the shade and large woody debris provided by large coniferous trees.

Influence of nitrogen additions on litter decomposition, nutrient dynamics, and enzymatic activity of two plant species in a peatland in Northeast China.

PubMed

Song, Yanyu; Song, Changchun; Ren, Jiusheng; Tan, Wenwen; Jin, Shaofei; Jiang, Lei

2018-06-01

Nitrogen (N) availability affects litter decomposition and nutrient dynamics, especially in N-limited ecosystems. We investigated the response of litter decomposition to N additions in Eriophorum vaginatum and Vaccinium uliginosum peatlands. These two species dominate peatlands in Northeast China. In 2012, mesh bags containing senesced leaf litter of Eriophorum vaginatum and Vaccinium uliginosum were placed in N addition plots and sprayed monthly for two years with NH 4 NO 3 solution at dose rates of 0, 6, 12, and 24gNm -2 year -1 (CK, N1, N2 and N3, respectively). Mass loss, N and phosphorus (P) content, and enzymatic activity were measured over time as litter decomposed. In the control plots, V. uliginosum litter decomposed faster than E. vaginatum litter. N1, N2, and N3 treatments increased the mass losses of V. uliginosum litter by 6%, 9%, and 4% respectively, when compared with control. No significant influence of N additions was found on the decomposition of E. vaginatum litter. However, N and P content in E. vaginatum litter and V. uliginosum litter significantly increased with N additions. Moreover, N additions significantly promoted invertase and β-glucosidase activity in E. vaginatum and V. uliginosum litter. However, only in V. uliginosum litter was polyphenol oxidase activity significantly enhanced. Our results showed that initial litter quality and polyphenol oxidase activity influence the response of plant litter to N additions in peatland ecosystems. Increased N availability may change peatland soil N and P cycling by enhancing N and P immobilization during litter decomposition. Copyright © 2018 Elsevier B.V. All rights reserved.

A canopy trimming experiment in Puerto Rico: The response of litter decomposition and nutrient release to canopy opening and debris deposition in a subtropical wet forest

Treesearch

G. Gonzalez; D.J. Lodge; B.A. Richardson; M.J. Richardson

2014-01-01

In this study, we used a replicated factorial design to separate the individual and interacting effects of two main components of a severe hurricane – canopy opening and green debris deposition on leaf litter decay in the tabonuco forest in the Luquillo Mountains of Puerto Rico. We quantify changes in percent mass remaining (PMR), the concentration and absolute amounts...

Transformation of leaf litter by insect herbivory in the Subarctic: Consequences for soil biogeochemistry under global change

NASA Astrophysics Data System (ADS)

Kristensen, J. A.; Metcalfe, D. B.; Rousk, J.

2017-12-01

Climate warming may increase insect herbivore ranges and outbreak intensities in arctic ecosystems. Thorough understanding of the implications of these changes for ecosystem processes is essential to make accurate predictions of surface-atmosphere carbon (C) feedbacks. Yet, we lack a comprehensive understanding of the impacts of herbivore outbreaks on soil microbial underpinnings of C and nitrogen (N) fluxes. Here, we investigate the growth responses of heterotrophic soil decomposers and C and N mineralisation to simulated defoliator outbreaks in Subarctic birch forests. In microcosms, topsoil was incubated with leaf litter, insect frass, mineral N and combinations of the three; all was added in equal amounts of N. A higher fraction of added C and N was mineralised during outbreaks (frass addition) relative to non-outbreak years (litter addition). However, under high mineral N-availability in the soil of the kind likely under longer periods of enhanced insect herbivory (litter+mineral N), the mineralised fraction of added C decreased while the mineralised fraction of N increased substantially, which suggest a shift towards more N-mining of the organic substrates. This shift was accompanied by higher fungal dominance, and may facilitate soil C-accumulation assuming constant quality of C-inputs. Thus, long-term increases of insect herbivory, of the kind observed in some areas and projected by some models, may facilitate higher ecosystem C-sink capacity in this Subarctic ecosystem.

Short chain nitrocompounds as a treatment of layer hen manure and litter; effects on in vitro survivability of Salmonella, generic E. coli and nitrogen metabolism.

PubMed

Ruiz-Barrera, Oscar; Anderson, Robin C; Hume, Michael E; Corrales-Millan, Jonatan; Castillo-Castillo, Yamicela; Corral-Luna, Agustin; Guevara-Valdez, Jose Luis; Salinas-Chavira, Jaime; Rodriguez-Muela, Carlos; Arzola-Alvarez, Claudio

2017-01-02

The current study was conducted to assess the bactericidal effectiveness of several nitrocompounds against pathogens in layer hen manure and litter. Evidence from an initial study indicated that treatment of layer hen manure with 12 mM nitroethane decreased populations of generic E. coli and total coliforms by 0.7 and 2.2 log 10 colony forming units (CFU) g -1 , respectively, after 24 h aerobic incubation at ambient temperature when compared to untreated populations. Salmonella concentrations were unaffected by nitroethane in this study. In a follow-up experiment, treatment of 6-month-old layer hen litter (mixed with 0.4 mL water g -1 ) with 44 mM 2-nitroethanol, 2-nitropropanol or ethyl nitroacetate decreased an inoculated Salmonella typhimurium strain from its initial concentration (3 log 10 CFU g -1 ) by 0.7 to 1.7 log 10 CFU g -1 after 6 h incubation at 37°C in covered containers. After 24 h incubation, populations of the inoculated S. Typhmiurium in litter treated with 44 mM 2-nitroethanol, 2-nitropropanol, ethyl nitroacetate or nitroethane were decreased more than 3.2 log 10 CFU g -1 compared to populations in untreated control litter. Treatment of litter with 44 mM 2-nitroethanol, 2-nitropropanol, ethyl nitroacetate decreased rates of ammonia accumulation more than 70% compared to untreated controls (0.167 µmol mL -1 h -1 ) and loses of uric acid (< 1 µmol mL -1 ) were observed only in litter treated with 44 mM 2-nitropropanol, indicating that some of these nitrocompounds may help prevent loss of nitrogen in treated litter. Results warrant further research to determine if these nitrocompounds can be developed into an environmentally sustainable and safe strategy to eliminate pathogens from poultry litter, while preserving its nitrogen content as a nutritionally valuable crude protein source for ruminants.

Resource-consumer diversity: testing the effects of leaf litter species diversity on stream macroinvertebrate communities.

Treesearch

John S. Kominoski; Catherine M. Pringle

2009-01-01

1. Understanding relationships between resource and consumer diversity is essential to predicting how changes in resource diversity might affect several trophic levels and overall ecosystem functioning...

Pesticides from wastewater treatment plant effluents affect invertebrate communities.

PubMed

Münze, Ronald; Hannemann, Christin; Orlinskiy, Polina; Gunold, Roman; Paschke, Albrecht; Foit, Kaarina; Becker, Jeremias; Kaske, Oliver; Paulsson, Elin; Peterson, Märit; Jernstedt, Henrik; Kreuger, Jenny; Schüürmann, Gerrit; Liess, Matthias

2017-12-01

We quantified pesticide contamination and its ecological impact up- and downstream of seven wastewater treatment plants (WWTPs) in rural and suburban areas of central Germany. During two sampling campaigns, time-weighted average pesticide concentrations (c TWA ) were obtained using Chemcatcher® passive samplers; pesticide peak concentrations were quantified with event-driven samplers. At downstream sites, receiving waters were additionally grab sampled for five selected pharmaceuticals. Ecological effects on macroinvertebrate structure and ecosystem function were assessed using the biological indicator system SPEAR pesticides (SPEcies At Risk) and leaf litter breakdown rates, respectively. WWTP effluents substantially increased insecticide and fungicide concentrations in receiving waters; in many cases, treated wastewater was the exclusive source for the neonicotinoid insecticides acetamiprid and imidacloprid in the investigated streams. During the ten weeks of the investigation, five out of the seven WWTPs increased in-stream pesticide toxicity by a factor of three. As a consequence, at downstream sites, SPEAR values and leaf litter degradation rates were reduced by 40% and 53%, respectively. The reduced leaf litter breakdown was related to changes in the macroinvertebrate communities described by SPEAR pesticides and not to altered microbial activity. Neonicotinoids showed the highest ecological relevance for the composition of invertebrate communities, occasionally exceeding the Regulatory Acceptable Concentrations (RACs). In general, considerable ecological effects of insecticides were observed above and below regulatory thresholds. Fungicides, herbicides and pharmaceuticals contributed only marginally to acute toxicity. We conclude that pesticide retention of WWTPs needs to be improved. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of broiler litter ash, layer manure ash and calcium phosphate on corn, wheat and soybean growth, phosphorus and arsenic uptake

USDA-ARS?s Scientific Manuscript database

Poultry litter is being incinerated in order to reduce excess litter and to increase the percentage of renewable fuel used to generate electricity. Ash from incinerated litter has been effective in increasing crop growth. However, there is no current literature comparing phosphorus availability fr...

Litter Species Composition and Topographic Effects on Fuels and Modeled Fire Behavior in an Oak-Hickory Forest in the Eastern USA

PubMed Central

Hutchinson, Todd F.; Dietenberger, Mark; Matt, Frederick; Peters, Matthew P.

2016-01-01

Mesophytic species (esp. Acer rubrum) are increasingly replacing oaks (Quercus spp.) in fire-suppressed, deciduous oak-hickory forests of the eastern US. A pivotal hypothesis is that fuel beds derived from mesophytic litter are less likely than beds derived from oak litter to carry a fire and, if they do, are more likely to burn at lower intensities. Species effects, however, are confounded by topographic gradients that affect overstory composition and fuel bed decomposition. To examine the separate and combined effects of litter species composition and topography on surface fuel beds, we conducted a common garden experiment in oak-hickory forests of the Ohio Hills. Each common garden included beds composed of mostly oak and mostly maple litter, representative of oak- and maple-dominated stands, respectively, and a mixture of the two. Beds were replenished each fall for four years. Common gardens (N = 16) were established at four topographic positions (ridges, benches on south- and northeast-facing slopes, and stream terraces) at each of four sites. Litter source and topographic position had largely independent effects on fuel beds and modeled fire dynamics after four years of development. Loading (kg m-2) of the upper litter layer (L), the layer that primarily supports flaming spread, was least in more mesic landscape positions and for maple beds, implying greater decomposition rates for those situations. Bulk density in the L layer (kg m-3) was least for oak beds which, along with higher loading, would promote fire spread and fireline intensity. Loading and bulk density of the combined fermentation and humic (FH) layers were least on stream terrace positions but were not related to species. Litter- and FH-layer moistures during a 5-day dry-down period after a rain event were affected by time and topographic effects while litter source effects were not evident. Characteristics of flaming combustion determined with a cone calorimeter pointed to greater fireline intensity for oak fuel beds and unexpected interactions between litter source and topography. A spread index, which synthesizes a suite of fuel bed, particle, and combustion characteristics to indicate spread (vs extinction) potential, was primarily affected by litter source and, secondarily, by the low spread potentials on mesic landscape positions early in the 5-day dry-down period. A similar result was obtained for modeled fireline intensity. Our results suggest that the continuing transition from oaks to mesophytic species in the Ohio Hills will reduce fire spread potentials and fire intensities. PMID:27536964

Litter Species Composition and Topographic Effects on Fuels and Modeled Fire Behavior in an Oak-Hickory Forest in the Eastern USA.

PubMed

Dickinson, Matthew B; Hutchinson, Todd F; Dietenberger, Mark; Matt, Frederick; Peters, Matthew P

2016-01-01

Mesophytic species (esp. Acer rubrum) are increasingly replacing oaks (Quercus spp.) in fire-suppressed, deciduous oak-hickory forests of the eastern US. A pivotal hypothesis is that fuel beds derived from mesophytic litter are less likely than beds derived from oak litter to carry a fire and, if they do, are more likely to burn at lower intensities. Species effects, however, are confounded by topographic gradients that affect overstory composition and fuel bed decomposition. To examine the separate and combined effects of litter species composition and topography on surface fuel beds, we conducted a common garden experiment in oak-hickory forests of the Ohio Hills. Each common garden included beds composed of mostly oak and mostly maple litter, representative of oak- and maple-dominated stands, respectively, and a mixture of the two. Beds were replenished each fall for four years. Common gardens (N = 16) were established at four topographic positions (ridges, benches on south- and northeast-facing slopes, and stream terraces) at each of four sites. Litter source and topographic position had largely independent effects on fuel beds and modeled fire dynamics after four years of development. Loading (kg m-2) of the upper litter layer (L), the layer that primarily supports flaming spread, was least in more mesic landscape positions and for maple beds, implying greater decomposition rates for those situations. Bulk density in the L layer (kg m-3) was least for oak beds which, along with higher loading, would promote fire spread and fireline intensity. Loading and bulk density of the combined fermentation and humic (FH) layers were least on stream terrace positions but were not related to species. Litter- and FH-layer moistures during a 5-day dry-down period after a rain event were affected by time and topographic effects while litter source effects were not evident. Characteristics of flaming combustion determined with a cone calorimeter pointed to greater fireline intensity for oak fuel beds and unexpected interactions between litter source and topography. A spread index, which synthesizes a suite of fuel bed, particle, and combustion characteristics to indicate spread (vs extinction) potential, was primarily affected by litter source and, secondarily, by the low spread potentials on mesic landscape positions early in the 5-day dry-down period. A similar result was obtained for modeled fireline intensity. Our results suggest that the continuing transition from oaks to mesophytic species in the Ohio Hills will reduce fire spread potentials and fire intensities.

Stream ecosystem integrity is impaired by logging and shifting agriculture in a global megadiversity center (Sarawak, Borneo).

PubMed

Jinggut, Tajang; Yule, Catherine M; Boyero, Luz

2012-10-15

In common with most of Borneo, the Bakun region of Sarawak is currently subject to heavy deforestation mainly due to logging and, to a lesser extent, traditional slash-and-burn farming practices. This has the potential to affect stream ecosystems, which are integrators of environmental change in the surrounding terrestrial landscape. This study evaluated the effects of both types of deforestation by using functional and structural indicators (leaf litter decomposition rates and associated detritivores or 'shredders', respectively) to compare a fundamental ecosystem process, leaf litter decomposition, within logged, farmed and pristine streams. Slash-and-burn agricultural practices increased the overall rate of decomposition despite a decrease in shredder species richness (but not shredder abundance) due to increased microbial decomposition. In contrast, decomposition by microbes and invertebrates was slowed down in the logged streams, where shredders were less abundant and less species rich. This study suggests that shredder communities are less affected by traditional agricultural farming practices, while modern mechanized deforestation has an adverse effect on both shredder communities and leaf breakdown. Copyright © 2012 Elsevier B.V. All rights reserved.

Contrasting effects of plant species traits and moisture on the decomposition of multiple litter fractions.

PubMed

Riggs, Charlotte E; Hobbie, Sarah E; Cavender-Bares, Jeannine; Savage, Jessica A; Wei, Xiaojing

2015-10-01

Environmental variation in moisture directly influences plant litter decomposition through effects on microbial activity, and indirectly via plant species traits. Whether the effects of moisture and plant species traits are mutually reinforcing or counteracting during decomposition are unknown. To disentangle the effects of moisture from the effects of species traits that vary with moisture, we decomposed leaf litter from 12 plant species in the willow family (Salicaceae) with different native habitat moisture preferences in paired mesic and wetland plots. We fit litter mass loss data to an exponential decomposition model and estimated the decay rate of the rapidly cycling litter fraction and size of the remaining fraction that decays at a rate approaching zero. Litter traits that covaried with moisture in the species' native habitat significantly influenced the decomposition rate of the rapidly cycling litter fraction, but moisture in the decomposition environment did not. In contrast, for the slowly cycling litter fraction, litter traits that did not covary with moisture in the species' native habitat and moisture in the decomposition environment were significant. Overall, the effects of moisture and plant species traits on litter decomposition were somewhat reinforcing along a hydrologic gradient that spanned mesic upland to wetland (but not permanently surface-saturated) plots. In this system, plant trait and moisture effects may lead to greater in situ decomposition rates of wetland species compared to upland species; however, plant traits that do not covary with moisture will also influence decomposition of the slowest cycling litter fraction.

Some Sensitivity Studies of Chemical Transport Simulated in Models of the Soil-Plant-Litter System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Begovich, C.L.

2002-10-28

Fifteen parameters in a set of five coupled models describing carbon, water, and chemical dynamics in the soil-plant-litter system were varied in a sensitivity analysis of model response. Results are presented for chemical distribution in the components of soil, plants, and litter along with selected responses of biomass, internal chemical transport (xylem and phloem pathways), and chemical uptake. Response and sensitivity coefficients are presented for up to 102 model outputs in an appendix. Two soil properties (chemical distribution coefficient and chemical solubility) and three plant properties (leaf chemical permeability, cuticle thickness, and root chemical conductivity) had the greatest influence onmore » chemical transport in the soil-plant-litter system under the conditions examined. Pollutant gas uptake (SO{sub 2}) increased with change in plant properties that increased plant growth. Heavy metal dynamics in litter responded to plant properties (phloem resistance, respiration characteristics) which induced changes in the chemical cycling to the litter system. Some of the SO{sub 2} and heavy metal responses were not expected but became apparent through the modeling analysis.« less

Soil Organic Carbon Sources of Respired CO2 in a Mid-successional North Temperate Forest

NASA Astrophysics Data System (ADS)

Medina, N. L.; Hatton, P. J.; Le Moine, J.; Nadelhoffer, K. J.

2015-12-01

Given that soil organic matter (SOM) is the largest global terrestrial carbon (C) pool, some fractions of which have turnover times of centuries to millennia, it is critical to understand the mechanisms by which higher net primary productivity (NPP) and higher litter inputs, in the future, as predicted by some models, might alter the potentials of forest soils to serve as long-term C sinks. Here, we use a 10-year-old site in the DIRT (Detritus Input and Removal Treatments) network of litter manipulations to compare plots in a forested, northern-temperate sandy soil that were subjected to double-leaf-litter additions (DL) and both root- and leaf-litter removals (no inputs, NI) to non-manipulated controls. Previous data show that rather than increasing soil organic carbon (SOC) stocks, plots receiving doubled litter inputs lose SOC at rates similar to losses in Control soils. To trace the source of extra mineralized SOC, we analyzed field CO2 effluxes for δ13C and characterized SOC of varying degrees of organo-mineral association with sequential density fractionations. Soils in DL plots respired significantly faster (p=0.095) and proportionally more (p=0.015) than control soils over the course of July, August, and October 2014. This suggests a greater fresh litter contribution to soil efflux in DL than in Control plots after 10 years of treatment. Preliminary data show that intermediate (1.85 - 2.4 g/mL) and dense (>2.4 g/mL) fractions are relatively larger in DL than in Control soils. This suggests that the addition C from doubled litter could be more rapidly transferred into those more dense fractions, or that higher litter inputs prime the decomposition of lighter particulate SOC forms, leading to a relative increase of the dense organo-mineral associations. Using δ13C values to parameterize a multi-source mixing model, we partition the fate of both fresh litter and partially-decomposed SOC and will present on the modeled relative contributions of various sources to field CO2 effluxes from diverse treatments. Our preliminary data and expected results may suggest important contributions from mineral-associated SOC, rather than simply from free SOC, to seasonal field soil respiration. Thus, with higher litterfall rates, C that similar forest soils sequester may exhibit shorter ecosystem-level residence times.

The Roles of Microbial Communities in n-Alkane Distribution of The Nanjenshan Lowland Subtropical Rainforest in Taiwan

NASA Astrophysics Data System (ADS)

Chen, Y. W.; Huang, T. Y.; Fan, C. W.; Chao, W. C.; Yang, T. N.; Huang, C. P.; Hsu, B. M.

2016-12-01

Analysis of total organic carbon in Nanjenshan, a lowland subtropical rainforest in southern Taiwan, revealed that the carbon storage of litter-layer was about 35% lower in ravine area than in windward and leeward areas, while the soil storage in these areas were similar. In this one year follow-up study, we aimed to investigate the kinetic changes of n-alkane (C14-C35) concentration from litter fall, litter-layer, surface soil, soil in -10 cm depth, and soil in -30 cm depth by a GC-FID method. The n-alkane distribution and n-alkane flux of these areas were also analyzed. Next generation sequencing was carried out to examine the metagenomics of uncultured microbial community in litter-layer of these areas. Our results showed that the net weight of one year-litter fall in ravine area was 30% higher than the others. The average concentration of n-alkane in leaves in ravine was 90% and 50% higher than in windward area and leeward area, respectively. Although the n-alkane flux in ravine area was twice higher than the other areas, the n-alkane concentrations in litter-layer and soils of different layers were similar among all areas, suggesting a rapid degradation of n-alkane in liter layer in ravine area. Interestingly, the character of odd over even predominance of n-alkane was gradually lost in soil layer in ravine area. Metagenomic data have showed that the structure of microbial abundance in ravine area was different from windward and leeward areas. In ravine area, the numbers in phyla of Bacteroidetes, Actinobacteria, and Proteobacteria, were higher than the other areas, while in phyla of Acidobacteria and Planctomycetes were lower. Our data provided evidence that microbial communities may not only play a role on n-alkane degradation but also change the profile in abundance of high-chain length n-alkanes.

Ecosystem and physiological scales of microbial responses to nutrients in a detritus-based stream: results of a 5-year continuous enrichment

Treesearch

Keller Suberkropp; Vladislav Gulis; Amy D. Rosemond; Jonathan Benstead

2010-01-01

Our study examined the response of leaf detritus–associated microorganisms (both bacteria and fungi) to a 5-yr continuous nutrient enrichment of a forested headwater stream. Leaf litter dominates detritus inputs to such streams and, on a system wide scale, serves as the key substrate for microbial colonization. We determined physiological responses as microbial biomass...

Dimilin effects on leaf-decomposing aquatic fungi on the Fernow Experimental Forest, West Virginia

Treesearch

T. Dubey; S. L. Stephenson; P. J. Edwards

1995-01-01

Dimilin was applied to two watersheds on the Fernow Experimental Forest on May 16,1992, as part of a study to evaluate its effect on non-target organisms. Data were obtained on the occurrence, conidial production, and leaf litter colonization of aquatic hyphomycetes 5 days prior to and 2, 10, 25, and 55 days following application in the two treated watersheds and two...

Who is who in litter decomposition? Metaproteomics reveals major microbial players and their biogeochemical functions

PubMed Central

Schneider, Thomas; Keiblinger, Katharina M; Schmid, Emanuel; Sterflinger-Gleixner, Katja; Ellersdorfer, Günther; Roschitzki, Bernd; Richter, Andreas; Eberl, Leo; Zechmeister-Boltenstern, Sophie; Riedel, Kathrin

2012-01-01

Leaf-litter decomposition is a central process in carbon cycling; however, our knowledge about the microbial regulation of this process is still scarce. Metaproteomics allows us to link the abundance and activity of enzymes during nutrient cycling to their phylogenetic origin based on proteins, the ‘active building blocks' in the system. Moreover, we employed metaproteomics to investigate the influence of environmental factors and nutrients on the decomposer structure and function during beech litter decomposition. Litter was collected at forest sites in Austria with different litter nutrient content. Proteins were analyzed by 1-D-SDS-PAGE followed by liquid-chromatography and tandem mass-spectrometry. Mass spectra were assigned to phylogenetic and functional groups by a newly developed bioinformatics workflow, assignments being validated by complementary approaches. We provide evidence that the litter nutrient content and the stoichiometry of C:N:P affect the decomposer community structure and activity. Fungi were found to be the main producers of extracellular hydrolytic enzymes, with no bacterial hydrolases being detected by our metaproteomics approach. Detailed investigation of microbial succession suggests that it is influenced by litter nutrient content. Microbial activity was stimulated at higher litter nutrient contents via a higher abundance and activity of extracellular enzymes. PMID:22402400

Direct and Indirect Effects of UV-B Exposure on Litter Decomposition: A Meta-Analysis

PubMed Central

Song, Xinzhang; Peng, Changhui; Jiang, Hong; Zhu, Qiuan; Wang, Weifeng

2013-01-01

Ultraviolet-B (UV-B) exposure in the course of litter decomposition may have a direct effect on decomposition rates via changing states of photodegradation or decomposer constitution in litter while UV-B exposure during growth periods may alter chemical compositions and physical properties of plants. Consequently, these changes will indirectly affect subsequent litter decomposition processes in soil. Although studies are available on both the positive and negative effects (including no observable effects) of UV-B exposure on litter decomposition, a comprehensive analysis leading to an adequate understanding remains unresolved. Using data from 93 studies across six biomes, this introductory meta-analysis found that elevated UV-B directly increased litter decomposition rates by 7% and indirectly by 12% while attenuated UV-B directly decreased litter decomposition rates by 23% and indirectly increased litter decomposition rates by 7%. However, neither positive nor negative effects were statistically significant. Woody plant litter decomposition seemed more sensitive to UV-B than herbaceous plant litter except under conditions of indirect effects of elevated UV-B. Furthermore, levels of UV-B intensity significantly affected litter decomposition response to UV-B (P<0.05). UV-B effects on litter decomposition were to a large degree compounded by climatic factors (e.g., MAP and MAT) (P<0.05) and litter chemistry (e.g., lignin content) (P<0.01). Results suggest these factors likely have a bearing on masking the important role of UV-B on litter decomposition. No significant differences in UV-B effects on litter decomposition were found between study types (field experiment vs. laboratory incubation), litter forms (leaf vs. needle), and decay duration. Indirect effects of elevated UV-B on litter decomposition significantly increased with decay duration (P<0.001). Additionally, relatively small changes in UV-B exposure intensity (30%) had significant direct effects on litter decomposition (P<0.05). The intent of this meta-analysis was to improve our understanding of the overall effects of UV-B on litter decomposition. PMID:23818993

The Influence of Plant Litter on Soil Water Repellency: Insight from 13C NMR Spectroscopy.

PubMed

Cesarano, Gaspare; Incerti, Guido; Bonanomi, Giuliano

2016-01-01

Soil water repellency (SWR, i.e. reduced affinity for water owing to the presence of organic hydrophobic coatings on soil particles) has relevant hydrological implications because low rates of infiltration enhance water runoff, and untargeted diffusion of fertilizers and pesticides. Previous studies investigated the occurrence of SWR in ecosystems with different vegetation cover but did not clarify its relationships with litter biochemical quality. Here, we investigated the capability of different plant litter types to induce SWR by using fresh and decomposed leaf materials from 12 species, to amend a model sandy soil over a year-long microcosm experiment. Water repellency, measured by the Molarity of an Ethanol Droplet (MED) test, was tested for the effects of litter species and age, and compared with litter quality assessed by 13C-CPMAS NMR in solid state and elemental chemical parameters. All litter types were highly water repellent, with MED values of 18% or higher. In contrast, when litter was incorporated into the soil, only undecomposed materials induced SWR, but with a large variability of onset and peak dynamics among litter types. Surprisingly, SWR induced by litter addition was unrelated to the aliphatic fraction of litter. In contrast, lignin-poor but labile C-rich litter, as defined by O-alkyl C and N-alkyl and methoxyl C of 13C-CPMAS NMR spectral regions, respectively, induced a stronger SWR. This study suggests that biochemical quality of plant litter is a major controlling factor of SWR and, by defining litter quality with 13C-CPMAS NMR, our results provide a significant novel contribution towards a full understanding of the relationships between plant litter biochemistry and SWR.

Restoration of Black Oak (Quercus velutina) Sand Barrens via Three Different Habitat Management Approaches

NASA Astrophysics Data System (ADS)

Kriska, David John

Disturbance regimes, i.e. frequent fires, historically maintained oak barrens until European settlement patterns, and eventually, Smoky the Bear and the fire suppression campaign of the U.S. Forest Service snuffed out the periodic flames. In the absence of a disturbance regime, ground layer floral composition at many historical oak sand barrens will change predominantly because of a buildup of leaf litter and shading of the soils. Termed mesophication, this process of ecological succession will drive Black Oak Sand Barrens to an alternate steady state. A survey conducted on Singer Lake Bog in Green, Ohio, demonstrated that succession shifted the community to red maple-black cherry woodlands more typical of a dry southern forest. In an attempt to revive disturbance, three restoration techniques were applied at ten degraded northeast Ohio oak barrens to contrast their effectiveness in restoring black oak sand barren flora. The three restoration treatments were select canopy tree reduction favoring 5% to 30% tree canopy cover, forest floor leaf litter removal, and prescribed fire. Vegetation responses to manipulations were monitored prior to and following treatment applications, and were compared against both baseline data from before-treatment surveys and paired control sites adjacent treated areas. Imposing disturbance successfully increased species diversity and abundance above that found across Singer Lake Bog compared to sampling made prior to and adjacent to treated areas. Select canopy tree removal exhibited the largest floral responses from targeted barrens species, i.e. graminoids. A forest floor invertebrate family (Carabidea: Coleoptera) was measured for species richness and abundance pre and post treatment, where a noticeable shift occurred away from woodland obligate ground beetles toward open grassland species. Replicating oak barren structure, prior to replicating disturbance processes, is the first step in the ecological restoration of these systems.

Leaf-Litter Breakdown

EPA Science Inventory

Terrestrial leaves are a major energy source for forested stream ecosystems around the world. Leaves entering streams as litterfall undergo a series of physical and chemical transformations mediated by internal chemistry and the interaction of microbes and invertebrates resulting...

The potential phototoxicity of nano-scale ZnO induced by visible light on freshwater ecosystems.

PubMed

Du, Jingjing; Qv, Mingxiang; Zhang, Yuyan; Yin, Xiaoyun; Wan, Ning; Zhang, Baozhong; Zhang, Hongzhong

2018-06-06

With the development of nanotechnology, nanomaterials have been widely applied in anti-bacterial coating, electronic device, and personal care products. NanoZnO is one of the most used materials and its ecotoxicity has been extensively studied. To explore the potential phototoxicity of nanoZnO induced by visible light, we conducted a long-term experiment on litter decomposition of Typha angustifolia leaves with assessment of fungal multifaceted natures. After 158 d exposure, the decomposition rate of leaf litter was decreased by nanoZnO but no additional effect by visible light. However, visible light enhanced the inhibitory effect of nanoZnO on fungal sporulation rate due to light-induced dissolution of nanoZnO. On the contrary, enzymes such as β-glucosidase, cellobiohydrolase, and leucine-aminopeptidase were significantly increased by the interaction of nanoZnO and visible light, which led to high efficiency of leaf carbon decomposition. Furthermore, different treatments and exposure time separated fungal community associated with litter decomposition. Therefore, the study provided the evidence of the contribution of visible light to nanoparticle phototoxicity at the ecosystem level. Copyright © 2018 Elsevier Ltd. All rights reserved.

Ant diversity as a direct and indirect driver of pselaphine rove beetle (Coleoptera: Staphylinidae) functional diversity in tropical rainforests, Sabah, Malaysian Borneo.

PubMed

Psomas, Elizabeth; Holdsworth, Sholto; Eggleton, Paul

2018-04-20

Pselaphinae is a species-rich beetle subfamily found globally, with many exhibiting myrmecophily-a symbiotic association with ants. Pselaphine-ant associations vary from facultative to obligate, but direct behavioral observations still remain scarce. Pselaphines are speciose and ecologically abundant within tropical leaf litter invertebrate communities where ants dominate, implying a potentially important ecological role that may be affected by habitat disturbances that impact ants. In this study, we measured and analyzed putative functional traits of leaf litter pselaphines associated with myrmecophily through morphometric analysis. We calculated "myrmecophile functional diversity" of pselaphines at different sites and examined this measure's relationship with ant abundance, in both old growth and logged rainforest sites in Sabah, Borneo. We show that myrmecophile functional diversity of pselaphine beetles increases as ant abundance increases. Old growth rainforest sites support a high abundance of ants, which is associated with a high abundance of probable myrmecophilous pselaphines. These results suggest a potential link between adult morphological characters and the functional role these beetles play in rainforest litter as ecological interaction partners with ants. © 2018 Wiley Periodicals, Inc.

Morphology and composition of beach-cast Posidonia oceanica litter on beaches with different exposures

NASA Astrophysics Data System (ADS)

Simeone, Simone; De Falco, Giovanni

2012-05-01

Posidonia oceanica seagrass litter is commonly found along sandy shores in the Mediterranean region, forming structures called banquettes, which are often removed in order to allow the beach to be used for tourism. This paper evaluates the relationship between the morphology and composition of banquettes and beach exposure to dominant waves. A Real Time Kinematic Differential Global Positioning System was used to evaluate the variability of banquettes and beach morphology over a period of 1 year. Banquette samples, collected at two different levels of the beach profile (i.e. foreshore and backshore), were used to evaluate the contribution of leaves, rhizomes and sediments to the total weight. Banquettes showed a higher volume, thickness and cross-shore length on exposed beaches, whereas narrower litter deposits were found on the sheltered beach. On exposed beaches, banquettes were deposited in beach zones characterized by changes in elevation. These changes in elevation were mainly due to the deposition and erosion of sediments and secondly to the deposition and or erosion of leaf litter. On sheltered beaches, the variability in beach morphology was low and was restricted to areas where the banquettes were located. The leaf/sediment ratio changed along the cross-shore profile. On the backshore, banquettes were a mixture of sediments and leaves, whereas leaves were the main component on the foreshore, independently of the beach exposure. The processes which control the morphodynamics in the swash zone could explain the variability of banquette composition along the cross-shore profile. Finally, this study highlighted that Posidonia oceanica seagrass litter plays an important role in the geomorphology of the beachface and its removal can have a harmful impact on the beaches.

How interacting fungal species and mineral nitrogen inputs affect transfer of nitrogen from litter via arbuscular mycorrhizal mycelium.

PubMed

He, Yuejun; Cornelissen, J Hans C; Zhong, Zhangcheng; Dong, Ming; Jiang, Changhong

2017-04-01

In the karst landscape, widespread in the world including southern China, soil nutrient supply is strongly constrained. In such environments, arbuscular mycorrhizal (AM) fungi may facilitate plant nutrient uptake. However, the possible role of different AM fungal species, and their interactions, especially in transferring nitrogen (N) from litter to plant, is poorly understood. We conducted two microcosm experiments to investigate the role that two karst soil AM fungi, Glomus etunicatum and Glomus mosseae, play in the transfer of N from decomposing litter to the host plant and to determine how N availability influences these processes. In experiment 1, Cinnamomum camphora tree seedlings were grown in compartments inoculated with G. etunicatum. Lolium perenne leaf litter labeled with δ 15 N was added to the soil in unplanted compartments. Compartments containing the δ 15 N labeled litter were either accessible to hyphae but not to seedling roots or were not accessible to hyphae or roots. The addition of mineral N to one of the host compartments at the start of the experiment significantly increased the biomass of the C. camphora seedlings, N content and N:P ratio, AM mycelium length, and soil microbial biomass carbon and N. However, significantly, more δ 15 N was acquired, from the leaf litter by the AM hyphae and transferred to the host when mineral N was not added to the soil. In experiment 2, in which C. camphora seedlings were inoculated with both G. etunicatum and G. mosseae rather than with G. mosseae alone, there was a significant increase in mycelial growth (50.21%), in soil microbial biomass carbon (417.73%) in the rhizosphere, and in the amount of δ 15 N that was transferred to the host. These findings suggest that maintaining AM fungal diversity in karst soils could be important for mediating N transfer from organic material to host plants in N-poor soils.

Predator effects on a detritus-based food web are primarily mediated by non-trophic interactions.

PubMed

Majdi, Nabil; Boiché, Anatole; Traunspurger, Walter; Lecerf, Antoine

2014-07-01

Predator effects on ecosystems can extend far beyond their prey and are often not solely lethally transmitted. Change in prey traits in response to predation risk can have important repercussions on community assembly and key ecosystem processes (i.e. trait-mediated indirect effects). In addition, some predators themselves alter habitat structure or nutrient cycling through ecological engineering effects. Tracking these non-trophic pathways is thus an important, yet challenging task to gain a better grasp of the functional role of predators. Multiple lines of evidence suggest that, in detritus-based food webs, non-trophic interactions may prevail over purely trophic interactions in determining predator effects on plant litter decomposition. This hypothesis was tested in a headwater stream by modulating the density of a flatworm predator (Polycelis felina) in enclosures containing oak (Quercus robur) leaf litter exposed to natural colonization by small invertebrates and microbial decomposers. Causal path modelling was used to infer how predator effects propagated through the food web. Flatworms accelerated litter decomposition through positive effects on microbial decomposers. The biomass of prey and non-prey invertebrates was not negatively affected by flatworms, suggesting that net predator effect on litter decomposition was primarily determined by non-trophic interactions. Flatworms enhanced the deposition and retention of fine sediments on leaf surface, thereby improving leaf colonization by invertebrates - most of which having strong affinities with interstitial habitats. This predator-induced improvement of habitat availability was attributed to the sticky nature of the mucus that flatworms secrete in copious amount while foraging. Results of path analyses further indicated that this bottom-up ecological engineering effect was as powerful as the top-down effect on invertebrate prey. Our findings suggest that predators have the potential to affect substantially carbon flow and nutrient cycling in detritus-based ecosystems and that this impact cannot be fully appreciated without considering non-trophic effects. © 2013 The Authors. Journal of Animal Ecology © 2013 British Ecological Society.

Transmission of Phytophthora ramorum in Mixed-Evergreen Forest in California.

PubMed

Davidson, Jennifer M; Wickland, Allison C; Patterson, Heather A; Falk, Kristen R; Rizzo, David M

2005-05-01

ABSTRACT During 2001 to 2003, the transmission biology of Phytophthora ramorum, the causal agent of sudden oak death, was studied in mixedevergreen forest, a common forest type in northern, coastal California. Investigation of the sources of spore production focused on coast live oak (Quercus agrifolia) and bay laurel (Umbellularia californica), dominant hosts that comprised 39.7 and 46.2% of the individuals at the study site, respectively. All tests for inoculum production from the surface of infected coast live oak bark or exudates from cankers were negative. In contrast, sporangia and chlamydospores were produced on the surface of infected bay laurel leaves. Mean number of zoospores produced from infected bay laurel leaves under natural field conditions during rainstorms was 1,173.0 +/- SE 301.48, and ranged as high as 5,200 spores/leaf. P. ramorum was recovered from rainwater, soil, litter, and streamwater during the mid- to late rainy season in all 3 years of the study. P. ramorum was not recovered from sporadic summer rains or soil and litter during the hot, dry summer months. Concentrations of inoculum in rainwater varied significantly from year to year and increased as the rainy season progressed for the two complete seasons that were studied. Potential dispersal distances were investigated for rainwater, soil, and streamwater. In rainwater, inoculum moved 5 and 10 m from the inoculum source. For soil, transmission of inoculum was demonstrated from infested soil to bay laurel green leaf litter, and from bay laurel green leaf litter to aerial leaves of bay laurel seedlings. One-third to one-half of the hikers tested at the study site during the rainy season also were carrying infested soil on their shoes. In streamwater, P. ramorum was recovered from an unforested site in pasture 1 km downstream of forest with inoculum sources. In total, these studies provide details on the production and spread of P. ramorum inoculum in mixed-evergreen forest to aid forecasting and managing disease transmission of this environmentally destructive pathogen.

Understanding litter decomposition in semiarid ecosystems: linking leaf traits, UV exposure and rainfall variability

PubMed Central

Gaxiola, Aurora; Armesto, Juan J.

2015-01-01

Differences in litter quality, microbial activity or abiotic conditions cannot fully account for the variability in decomposition rates observed in semiarid ecosystems. Here we tested the role of variation in litter quality, water supply, and UV radiation as drivers of litter decomposition in arid lands. And show that carry-over effects of litter photodegradation during dry periods can regulate decomposition during subsequent wet periods. We present data from a two-phase experiment, where we first exposed litter from a drought-deciduous and an evergreen shrub to natural UV levels during five, rainless summer months and, subsequently, in the laboratory, we assessed the carry-over effects of photodegradation on biomass loss under different irrigation treatments representing the observed range of local rainfall variation among years (15–240 mm). Photodegradation of litter in the field produced average carbon losses of 12%, but deciduous Proustia pungens lost >25%, while evergreen Porlieria chilensis less than 5%. Natural exposure to UV significantly reduced carbon-to-nitrogen and lignin:N ratios in Proustia litter but not in Porlieria. During the subsequent wet phase, remaining litter biomass was lower in Proustia than in Porlieria. Indeed UV exposure increased litter decomposition of Proustia under low and medium rainfall treatments, whereas no carry-over effects were detected under high rainfall treatment. Consequently, for deciduous Proustia carry-over effects of UV exposure were negligible under high irrigation. Litter decomposition of the evergreen Porlieria depended solely on levels of rainfall that promote microbial decomposers. Our two-phase experiment revealed that both the carry-over effects of photodegradation and litter quality, modulated by inter-annual variability in rainfall, can explain the marked differences in decomposition rates and the frequent decoupling between rainfall and litter decomposition observed in semiarid ecosystems. PMID:25852705

[Effects of grazing on the composition of soil animals and their decomposition function to Stipa grandis litter in Inner Mongolia typical steppe, China.

PubMed

Yang, Zhi Min; Hasitamier; Liu, Xin Min

2016-09-01

Grazing has been considered to be an important factor determining the composition of soil animals and decomposition of leaf litter in grassland ecosystem. Sampling plots were selected in ungrazed grassland, grazed grassland and sandy land. Litter bags were used to compare the changes of physicochemical properties of Stipa grandis litter and the composition of soil fauna in the process of the litter decomposition in Baiyinxile, Inner Mongolia, since 2010 to 2012. A total number of 67056 soil animals were captured, belonging to five phyla and eight classes, including 23 families of mites and 19 families of insects. After 780 days' decomposition, the loss of the organic matter of S. grandis litter was from 92.5% to 40.0% in the ungrazed grassland, and to 41.3% in the grazed grassland, with no significant difference observed. However, there was a significant difference (P<0.05) between the ratio of litter residues of the ungrazed grassland (50.0%) and that of the grazed grassland (23.0%). The abundance of soil animals in the residual litters was significantly decreased in the grazed grassland compared to the ungrazed grassland. When the litter was moved into the sandy land, the decomposition rate of organic matter in the residual litter was not significant changed but the ratio of litter residue declined significantly, and the composition of mite community in the resi-dual litter changed significantly. Our results illustrated that grazing activity could affect the composition and abundance of soil fauna in temperate grassland, but slightly influenced the decomposition of organic matter. Therefore, soil animals had relatively weak direct effects on the decomposition of litter in this semi-arid region.

Understanding litter decomposition in semiarid ecosystems: linking leaf traits, UV exposure and rainfall variability.

PubMed

Gaxiola, Aurora; Armesto, Juan J

2015-01-01

Differences in litter quality, microbial activity or abiotic conditions cannot fully account for the variability in decomposition rates observed in semiarid ecosystems. Here we tested the role of variation in litter quality, water supply, and UV radiation as drivers of litter decomposition in arid lands. And show that carry-over effects of litter photodegradation during dry periods can regulate decomposition during subsequent wet periods. We present data from a two-phase experiment, where we first exposed litter from a drought-deciduous and an evergreen shrub to natural UV levels during five, rainless summer months and, subsequently, in the laboratory, we assessed the carry-over effects of photodegradation on biomass loss under different irrigation treatments representing the observed range of local rainfall variation among years (15-240 mm). Photodegradation of litter in the field produced average carbon losses of 12%, but deciduous Proustia pungens lost >25%, while evergreen Porlieria chilensis less than 5%. Natural exposure to UV significantly reduced carbon-to-nitrogen and lignin:N ratios in Proustia litter but not in Porlieria. During the subsequent wet phase, remaining litter biomass was lower in Proustia than in Porlieria. Indeed UV exposure increased litter decomposition of Proustia under low and medium rainfall treatments, whereas no carry-over effects were detected under high rainfall treatment. Consequently, for deciduous Proustia carry-over effects of UV exposure were negligible under high irrigation. Litter decomposition of the evergreen Porlieria depended solely on levels of rainfall that promote microbial decomposers. Our two-phase experiment revealed that both the carry-over effects of photodegradation and litter quality, modulated by inter-annual variability in rainfall, can explain the marked differences in decomposition rates and the frequent decoupling between rainfall and litter decomposition observed in semiarid ecosystems.

Biogenic nitric oxide emission from a spruce forest soil in mountainous terrain

NASA Astrophysics Data System (ADS)

Falge, Eva; Bargsten, Anika; Behrendt, Thomas; Meixner, Franz X.

2010-05-01

The process-based spatial simulation model SVAT-CN was used to estimate biogenic nitric oxide (NO) emission by soils of a Norway spruce forest (Weidenbrunnen) in the Fichtelgebirge, Germany. SVAT-CN core is a combination of a multiple-layer soil water balance model and a multi-layered canopy gas exchange model. The soil modules comprise a flexible hybrid between a layered bucket model and classical basic liquid flow theory. Further soil processes include: heat transport, distribution of transpiration demand proportionally to soil resistance, reduction of leaf physiological parameters with limiting soil moisture. Spruce forest soils usually are characterized by a thick organic layer (raw humus), with the topmost centimetres being the location where most of the biogenic NO is produced. Within individual spruce forest stands the understory might be composed of patches characterized by different species (e.g. Vaccinium myrtillus, Picea abies, Deschampsia caespitosa), and NO production potentials. The effect of soil physical and chemical parameters and understory types on NO emission from the organic layer was investigated in laboratory incubation and fumigation experiments on soils sampled below the various understory covers found at the Weidenbrunnen site. Results from the laboratory experiments were used to parameterize multi-factorial regression models of soil NO emission with respect to its response to soil temperature and moisture. Parameterization of the spatial model SVAT-CN includes horizontal heterogeneity of over- and understory PAI, understory species distribution, soil texture, bulk density, thickness of organic layer. Simulations are run for intensive observations periods of 2007 and 2008 of the EGER (ExchanGE processes in mountainous Regions) project, a late summer/fall and an early summer period, providing estimates for different understory types (young spruce, blueberry, grass, and moss/litter patches). Validation of the model is being carried out at point scale, by comparison with measured soil moisture and temperature data at 12 locations at the Weidenbrunnen site. In addition model output is compared to soil NO emission data from dynamic chambers. Understory type was found to have a strong influence on the magnitude of soil NO emissions, with emissions from blueberry and young spruce one order of magnitude larger than those from grass or moss/litter patches.

A TWO-PROBE METHOD FOR MEASURING WATER CONTENT OF THIN FOREST FLOOR LITTER LAYERS USING TIME DOMAIN REFLECTOMETRY

EPA Science Inventory

Few methods exist that allow non-destructive in situ measurement of the water content of forest floor litter layers (Oa,Oe, and Oi horizons). Continuous non-destructive measurement is needed in studies of ecosystem processes because of the relationship between physical structure ...

CADDIS Volume 2. Sources, Stressors and Responses: Urbanization - Energy Sources

EPA Pesticide Factsheets

Introduction to changes in basal energy sources with urbanization, overview of terrestrial leaf litter dynamics in urban streams, overview of how urbanization can affect primary production, respiration, and dissolved organic carbon quantity and quality.

Leaf litter copepods from a cloud forest mountain top in Honduras (Copepoda: Cyclopidae, Canthocamptidae).

PubMed

Fiers, Frank; Jocque, Merlijn

2013-01-01

Five different species of Copepoda were extracted from a leaf litter sample collected on the top (at 2000 m a.s.l.) of a cloud forested mountain in El Cusuco National Park, Honduras. Three of them, one Cyclopidae and two Canthocamptidae are new to science, and are described herein. Olmeccyclops hondo sp. nov. is the second representative thus far known of this New World genus. Moraria catracha sp. nov. and Moraria cusuca sp. nov. are the first formally described members of the genus occurring in Central America. The concept of a "Moraria-group" is considered to be an artificial grouping and is limited here to the genera Moraria and Morariopsis only. The distributional range of this group is essentially Holarctic, with the mountainous regions in Honduras, and probably in west Nicaragua, as the southernmost limits in the New World.

Five new, microendemic Asian Leaf-litter Frogs (Leptolalax) from the southern Annamite mountains, Vietnam.

PubMed

Rowley, Jodi J L; Tran, Dao T A; Le, Duong T T; Dau, Vinh Q; Peloso, Pedro L V; Nguyen, Truong Q; Hoang, Huy D; Nguyen, Tao T; Ziegler, Thomas

2016-03-01

The Leptolalax applebyi group of Asian leaf-litter frogs currently comprises four species of particularly small-bodied (<40 mm SVL) species distributed in the Central Highlands of Vietnam and northeastern Cambodia. In addition to their small size, the group is characterized by their morphological and genetic similarities, as well as their breeding habitat at headwaters of small mountain streams and seeps. A recent study suggested that at least two-thirds of the diversity of the group remained hidden within morphologically cryptic lineages. We expand upon the molecular, morphometric, and acoustic data and formally delineate and describe five of these lineages as distinct species: Leptolalax ardens sp. nov., Leptolalax kalonensis sp. nov., Leptolalax pallidus sp. nov., Leptolalax maculosus sp. nov., and Leptolalax tadungensis sp. nov. Due to habitat loss, the current ranges of these species are likely to be a fraction of their historical extent and under continued threat from deforestation.

Oribatid mites and nutrient cycling. [Nutrient release by decomposition of leaf litter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crossley, D.A. Jr.

1976-08-01

Communities of oribatid mites (Cryptostigmata) in leaf litter and forest soils consist of an impressive number of individuals. Total populations of the order of 10/sup 5/ oribatids per square meter are commonly reported from forest floors. Because of their numbers, oribatids have been believed to be important contributors to the breakdown of organic detritus. Results are reported from studies of mineral or nutrient element cycling in forest floor ecosystems using radioisotopes as tracers. The phenomenon of cycling allows for the study of feedback loops among ecosystem processes, whereas energy flow is unidirectional. Evaluation of feedback loops can be a meansmore » of quantifying indirect effects of consumers. The availability of radioactive isotopes or radioactive analogs of mineral elements allows for the direct measurement of transfer rates. In decomposition studies applications of radioactive tracers have helped to identify pathways of transfer from microflora to oribatids.« less

Soil and leaf litter metaproteomics—a brief guideline from sampling to understanding

PubMed Central

Keiblinger, Katharina M.; Fuchs, Stephan; Zechmeister-Boltenstern, Sophie; Riedel, Katharina

2016-01-01

The increasing application of soil metaproteomics is providing unprecedented, in-depth characterization of the composition and functionality of in situ microbial communities. Despite recent advances in high-resolution mass spectrometry, soil metaproteomics still suffers from a lack of effective and reproducible protein extraction protocols and standardized data analyses. This review discusses the opportunities and limitations of selected techniques in soil-, and leaf litter metaproteomics, and presents a step-by-step guideline on their application, covering sampling, sample preparation, extraction and data evaluation strategies. In addition, we present recent applications of soil metaproteomics and discuss how such approaches, linking phylogenetics and functionality, can help gain deeper insights into terrestrial microbial ecology. Finally, we strongly recommend that to maximize the insights environmental metaproteomics may provide, such methods should be employed within a holistic experimental approach considering relevant aboveground and belowground ecosystem parameters. PMID:27549116

Environmental influence on coprophagous Scarabaeidae (Insecta, Coleoptera) assemblages in the Pantanal of Mato Grosso.

PubMed

Tissiani, A S O; Sousa, W O; Santos, G B; Ide, S; Battirola, L; Marques, M I

2015-11-01

Here we examine assemblage structure of coprophagous Scarabaeidae (dung beetles) in the Pantanal of the state of Mato Grosso with respect to flooding regimes, soil texture, leaf litter volume and tree dominance in native and exotic pastures. Samples were collected along 30 transects of 250 m in length in a 5×5 km grid (25 km2). Five pitfalls baited with human feces were placed in each transect. A total of 1692 individuals in 19 species were captured, the majority in the subfamily Scarabaeinae and Aphodiinae. Assemblages were influenced by the duration of flooding and leaf litter volume. None of the other habitat variables was correlated with species richness. Cultivated pastures with exotic grasses were unimportant for composition of the assemblages of beetles. These results indicate that duration of flooding is the most important regulating force in this community.

Rarity and diversity in forest ant assemblages of Great Smoky Mountains National Park

USGS Publications Warehouse

Lessard, J.-P.; Dunn, R.R.; Parker, C.R.; Sanders, N.J.

2007-01-01

We report on a systematic survey of the ant fauna occurring in hardwood forests in the Great Smoky Mountains National Park. At 22-mixed hardwood sites, we collected leaf-litter ant species using Winkler samplers. At eight of those sites, we also collected ants using pitfall and Malaise traps. In total, we collected 53 ant species. As shown in other studies, ant species richness tended to decline with increasing elevation. Leaf-litter ant assemblages were also highly nested. Several common species were both locally abundant and had broad distributions, while many other species were rarely detected. Winkler samplers, pitfall traps, and Malaise traps yielded samples that differed in composition, but not richness, from one another. Taken together, our work begins to illuminate the factors that govern the diversity, distribution, abundance, and perhaps rarity of ants of forested ecosystems in the Great Smoky Mountains National Park.

Feeding Ecology of Two Plecopterans in Low Order Andean-Patagonian Streams

NASA Astrophysics Data System (ADS)

Albariño, Ricardo J.; Díaz Villanueva, Verónica

2006-05-01

Feeding plasticity of the Andean plecopteran Klapopteryx kuscheli and Notoperla archiplatae larvae was assessed through a field experiment using enclosures. K. kuscheli has previously been described as a shredder and N. archiplatae as a scraper. Further information on gut contents from different populations supported those results. In the experiment, larvae of both species were exposed to contrasting food items: leaf litter and periphyton. Consumption, growth and the efficiency of food conversion were measured. K. kuscheli was able to feed on periphyton, though it did not grow. N. archiplatae failed to feed on leaf litter. While K. kuscheli might be considered a facultative shredder, N. archiplatae functions as a specialist scraper. The natural distribution and seasonal abundance in two small streams showed contrasting habitat use of both species. N. archiplatae inhabited high velocity runs and riffles underneath large substrates while K. kuscheli presented a higher habitat plasticity. Implications of those results for ecosystem function are discussed.

Distinct Microbial Limitations in Litter and Underlying Soil Revealed by Carbon and Nutrient Fertilization in a Tropical Rainforest

PubMed Central

Fanin, Nicolas; Barantal, Sandra; Fromin, Nathalie; Schimann, Heidy; Schevin, Patrick; Hättenschwiler, Stephan

2012-01-01

Human-caused alterations of the carbon and nutrient cycles are expected to impact tropical ecosystems in the near future. Here we evaluated how a combined change in carbon (C), nitrogen (N) and phosphorus (P) availability affects soil and litter microbial respiration and litter decomposition in an undisturbed Amazonian rainforest in French Guiana. In a fully factorial C (as cellulose), N (as urea), and P (as phosphate) fertilization experiment we analyzed a total of 540 litterbag-soil pairs after a 158-day exposure in the field. Rates of substrate-induced respiration (SIR) measured in litter and litter mass loss were similarly affected by fertilization showing the strongest stimulation when N and P were added simultaneously. The stimulating NP effect on litter SIR increased considerably with increasing initial dissolved organic carbon (DOC) concentrations in litter, suggesting that the combined availability of N, P, and a labile C source has a particularly strong effect on microbial activity. Cellulose fertilization, however, did not further stimulate the NP effect. In contrast to litter SIR and litter mass loss, soil SIR was reduced with N fertilization and showed only a positive effect in response to P fertilization that was further enhanced with additional C fertilization. Our data suggest that increased nutrient enrichment in the studied Amazonian rainforest can considerably change microbial activity and litter decomposition, and that these effects differ between the litter layer and the underlying soil. Any resulting change in relative C and nutrient fluxes between the litter layer and the soil can have important consequences for biogeochemical cycles in tropical forest ecosystems. PMID:23272052

Mercury accumulation in the surface layers of mountain soils: a case study from the Karkonosze Mountains, Poland.

PubMed

Szopka, Katarzyna; Karczewska, Anna; Kabała, Cezary

2011-06-01

The study was aimed to examine total concentrations and pools of Hg in surface layers of soils in the Karkonosze Mountains, dependent on soil properties and site locality. Soil samples were collected from a litter layer and the layers 0-10 cm and 10-20 cm, at 68 sites belonging to the net of a monitoring system, in two separate areas, and in three altitudinal zones: below 900 m, 900-1100 m, and over 1100 m. Air-borne pollution was the major source of mercury in soils. Hg has accumulated mainly in the litter (where its concentrations were the highest), and in the layer 0-10 cm. Hg concentrations in all samples were in the range 0.04-0.97 mg kg(-1), with mean values 0.38, 0.28, and 0.14 mg kg(-1) for litter and the layers 0-10 cm and 10-20 cm, respectively. The highest Hg concentrations in the litter layer were found in the intermediate altitudinal zone, whereas Hg concentrations in the layer 0-10 cm increased with increasing altitude. Soil quality standard for protected areas (0.50 mg kg(-1)) was exceeded in a few sites. The pools of Hg accumulated in soils were in the range: 0.8-84.8 mg m(-2), with a mean value of 16.5 mg m(-2), and they correlated strongly with the pools of stored organic matter. Copyright © 2011 Elsevier Ltd. All rights reserved.

Hibernal habitat selection by Wood Frogs (Lithobates sylvaticus) in a northern New England montane landscape

USGS Publications Warehouse

Groff, Luke A.; Calhoun, Aram J.K.; Loftin, Cynthia S.

2016-01-01

Poikilothermic species, such as amphibians, endure harsh winter conditions via freeze-tolerance or freeze-avoidance strategies. Freeze-tolerance requires a suite of complex, physiological mechanisms (e.g., cryoprotectant synthesis); however, behavioral strategies (e.g., hibernal habitat selection) may be used to regulate hibernaculum temperatures and promote overwintering survival. We investigated the hibernal ecology of the freeze-tolerant Wood Frog (Lithobates sylvaticus) in north-central Maine. Our objectives were to characterize the species hibernaculum microclimate (temperature, relative humidity), evaluate hibernal habitat selection, and describe the spatial arrangement of breeding, post-breeding, and hibernal habitats. We monitored 15 frogs during two winters (2011/12: N = 10; 2012/13: N = 5), measured hibernal habitat features at micro (2 m) and macro (10 m) spatial scales, and recorded microclimate hourly in three strata (hibernaculum, leaf litter, ambient air). We compared these data to that of 57 random locations with logistic regression models, Akaike Information Criterion, and Kolmogorov–Smirnov tests. Hibernaculum microclimate was significantly different and less variable than leaf litter, ambient air, and random location microclimate. Model averaging indicated that canopy cover (−), leaf litter depth (+), and number of logs and stumps (+; microhabitat only) were important predictors of Wood Frog hibernal habitat. These habitat features likely act to insulate hibernating frogs from extreme and variable air temperatures. For example, decreased canopy cover facilitates increased snowpack depth and earlier snowpack accumulation and melt. Altered winter temperature and precipitation patterns attributable to climate change may reduce snowpack insulation, facilitate greater temperature variation in the underlying hibernacula, and potentially compromise Wood Frog winter survival.

Climatic Control on Plant and Soil δ13C along an Altitudinal Transect of Lushan Mountain in Subtropical China: Characteristics and Interpretation of Soil Carbon Dynamics

PubMed Central

Du, Baoming; Liu, Chunjiang; Kang, Hongzhang; Zhu, Penghua; Yin, Shan; Shen, Guangrong; Hou, Jingli; Ilvesniemi, Hannu

2014-01-01

Decreasing temperature and increasing precipitation along altitude gradients are typical mountain climate in subtropical China. In such a climate regime, identifying the patterns of the C stable isotope composition (δ13C) in plants and soils and their relations to the context of climate change is essential. In this study, the patterns of δ13C variation were investigated for tree leaves, litters, and soils in the natural secondary forests at four altitudes (219, 405, 780, and 1268 m a.s.l.) in Lushan Mountain, central subtropical China. For the dominant trees, both leaf and leaf-litter δ13C decreased as altitude increased from low to high altitude, whereas surface soil δ13C increased. The lower leaf δ13C at high altitudes was associated with the high moisture-related discrimination, while the high soil δ13C is attributed to the low temperature-induced decay. At each altitude, soil δ13C became enriched with soil depth. Soil δ13C increased with soil C concentrations and altitude, but decreased with soil depth. A negative relationship was also found between O-alkyl C and δ13C in litter and soil, whereas a positive relationship was observed between aromatic C and δ13C. Lower temperature and higher moisture at high altitudes are the predominant control factors of δ13C variation in plants and soils. These results help understand C dynamics in the context of global warming. PMID:24466099

Chemical composition and phytotoxicity of volatile essential oil from intact and fallen leaves of Eucalyptus citriodora.

PubMed

Batish, Daizy R; Singh, Harminder P; Setia, Nidhi; Kaur, Shalinder; Kohli, Ravinder K

2006-01-01

A total of 23 volatile constituents was identified and characterized by GC and GC-MS in the volatile essential oil extracted from intact (juvenile and adult) and fallen (senescent and leaf litter) leaves of lemon-scented eucalyptus (Eucalyptus citriodora Hook.). The leaves differed in their pigment, water and protein content, and C/N ratio. The oils were, in general, monoterpenoid in nature with 18 monoterpenes and 5 sesquiterpenes. However, a great variability in the amount of essential oils and their individual constituents was observed in different leaf tissues. The amount was maximum in the senescent leaves collected from the floor of the tree closely followed by that from juvenile leaves. In all, 19 constituents were identified in oil from juvenile and senescent leaves compared to 23 in adult leaves and 20 in leaf litter, respectively. Citronellal, a characteristic monoterpene of the oil reported hitherto was found to be more (77-78%) in the juvenile and senescent leaves compared to 48 and 54%, respectively, in the adult leaves and leaf litter. In the adult leaves, however, the content of citronellol--another important monoterpene-- was very high (21.9%) compared to other leaf types (7.8-12.2%). Essential oil and its two major monoterpenes viz. citronellal and citronellol were tested for their phytotoxicity against two weeds (Amaranthus viridis and Echinochloa crus-galli) and two crops (Triticum aestivum and Oryza sativa) under laboratory conditions. A difference in the phytotoxicity, measured in terms of seedling length and dry weight, of oil from different leaves and major monoterpenes was observed. Oil from adult leaves was found to be most phytotoxic although it occurs in smaller amount (on unit weight basis). The different toxicity of different oil types was due to the relative amount of individual monoterpenes present in the oil, their solubility and interactive action. The study concludes that oil from senescent and juvenile leaves being rich in citronellal could be used as commercial source of citronellal whereas that from adult leaves for weed management programmes as it was the most phytotoxic.

Climate change effects on macrofaunal litter decomposition: the interplay of temperature, body masses and stoichiometry.

PubMed

Ott, David; Rall, Björn C; Brose, Ulrich

2012-11-05

Macrofauna invertebrates of forest floors provide important functions in the decomposition process of soil organic matter, which is affected by the nutrient stoichiometry of the leaf litter. Climate change effects on forest ecosystems include warming and decreasing litter quality (e.g. higher C : nutrient ratios) induced by higher atmospheric CO(2) concentrations. While litter-bag experiments unravelled separate effects, a mechanistic understanding of how interactions between temperature and litter stoichiometry are driving decomposition rates is lacking. In a laboratory experiment, we filled this void by quantifying decomposer consumption rates analogous to predator-prey functional responses that include the mechanistic parameters handling time and attack rate. Systematically, we varied the body masses of isopods, the environmental temperature and the resource between poor (hornbeam) and good quality (ash). We found that attack rates increased and handling times decreased (i) with body masses and (ii) temperature. Interestingly, these relationships interacted with litter quality: small isopods possibly avoided the poorer resource, whereas large isopods exhibited increased, compensatory feeding of the poorer resource, which may be explained by their higher metabolic demands. The combination of metabolic theory and ecological stoichiometry provided critically important mechanistic insights into how warming and varying litter quality may modify macrofaunal decomposition rates.

Microdiversity of an Abundant Terrestrial Bacterium Encompasses Extensive Variation in Ecologically Relevant Traits

DOE PAGES

Chase, Alexander B.; Karaoz, Ulas; Brodie, Eoin L.; ...

2017-11-14

Much genetic diversity within a bacterial community is likely obscured by microdiversity within operational taxonomic units (OTUs) defined by 16S rRNA gene sequences. However, it is unclear how variation within this microdiversity influences ecologically relevant traits. Here, we employ a multifaceted approach to investigate microdiversity within the dominant leaf litter bacterium,Curtobacterium, which comprises 7.8% of the bacterial community at a grassland site undergoing global change manipulations. We use cultured bacterial isolates to interpret metagenomic data, collectedin situover 2 years, together with lab-based physiological assays to determine the extent of trait variation within this abundant OTU. The response ofCurtobacteriumto seasonal variability andmore » the global change manipulations, specifically an increase in relative abundance under decreased water availability, appeared to be conserved across sixCurtobacteriumlineages identified at this site. Genomic and physiological analyses in the lab revealed that degradation of abundant polymeric carbohydrates within leaf litter, cellulose and xylan, is nearly universal across the genus, which may contribute to its high abundance in grassland leaf litter. However, the degree of carbohydrate utilization and temperature preference for this degradation varied greatly among clades. Overall, we find that traits withinCurtobacteriumare conserved at different phylogenetic depths. We speculate that similar to bacteria in marine systems, diverse microbes within this taxon may be structured in distinct ecotypes that are key to understandingCurtobacteriumabundance and distribution in the environment. IMPORTANCE. Despite the plummeting costs of sequencing, characterizing the fine-scale genetic diversity of a microbial community—and interpreting its functional importance—remains a challenge. Indeed, most studies, particularly studies of soil, assess community composition at a broad genetic level by classifying diversity into taxa (OTUs) defined by 16S rRNA sequence similarity. However, these classifications potentially obscure variation in traits that result in fine-scale ecological differentiation among closely related strains. Here, we investigated “microdiversity” in a highly diverse and poorly characterized soil system (leaf litter in a southern Californian grassland). Here, we focused on the most abundant bacterium,Curtobacterium, which by standard methods is grouped into only one OTU. We find that the degree of carbohydrate usage and temperature preference vary within the OTU, whereas its responses to changes in precipitation are relatively uniform. These results suggest that microdiversity may be key to understanding how soil bacterial diversity is linked to ecosystem functioning.« less

Seasonal changes in the communities of microorganisms and algae in the litters of tree plantations in the steppe zone

NASA Astrophysics Data System (ADS)

Maltsev, Ye. I.; Didovich, S. V.; Maltseva, I. A.

2017-08-01

Specific structural and dynamic parameters of communities from various ecological and trophic groups of microorganisms and algae in the litter of artificial tree stands were studied using the example of the Staro-Berdyansky Forest in the steppe zone of Ukraine. The composition of the communities was shown to vary by seasons and depend on the forest-forming woody species. In spring, in all the litters, the maximal number of actinomycetes and aminotrophs was recorded; in the leaf litter, the number of phosphate-mobilizing organisms was also the largest. In summer, the development of cellulolytic organisms, ammonifiers, and nitrogen-fixers was intensified; in autumn, the number of micromycetes and oligotrophic organisms decreased. The composition of dominants, the species richness of algae and their abundance also varied by seasons. Representatives of the Chlorophyta division predominated. The highest species richness of algae was characteristic of the spring litter samples, and their number, for the spring and autumn ones. The positive correlation was established between the numbers of micromycetes and oligotrophs, micromycetes and algae. The negative correlation was found between the numbers of micromycetes and actinomycetes, cellulose-decompose bacteria and algae in the litters.

[Organic carbon and carbon mineralization characteristics in nature forestry soil].

PubMed

Yang, Tian; Dai, Wei; An, Xiao-Juan; Pang, Huan; Zou, Jian-Mei; Zhang, Rui

2014-03-01

Through field investigation and indoor analysis, the organic carbon content and organic carbon mineralization characteristics of six kinds of natural forest soil were studied, including the pine forests, evergreen broad-leaved forest, deciduous broad-leaved forest, mixed needle leaf and Korean pine and Chinese pine forest. The results showed that the organic carbon content in the forest soil showed trends of gradual decrease with the increase of soil depth; Double exponential equation fitted well with the organic carbon mineralization process in natural forest soil, accurately reflecting the mineralization reaction characteristics of the natural forest soil. Natural forest soil in each layer had the same mineralization reaction trend, but different intensity. Among them, the reaction intensity in the 0-10 cm soil of the Korean pine forest was the highest, and the intensities of mineralization reaction in its lower layers were also significantly higher than those in the same layers of other natural forest soil; comparison of soil mineralization characteristics of the deciduous broad-leaved forest and coniferous and broad-leaved mixed forest found that the differences of litter species had a relatively strong impact on the active organic carbon content in soil, leading to different characteristics of mineralization reaction.

Measuring forest floor evaporation from interception in prescribed burned forests in Southern Italy.

NASA Astrophysics Data System (ADS)

Giuditta, Elisabetta; Coenders-Gerrits, Miriam; Bogaard, Thom; Wenninger, Jochen; Greco, Roberto; Ialongo, Gianluca; Esposito, Assunta; Rutigliano, Flora Angela

2016-04-01

Wildfires are one of the major environmental issue in the Mediterranean area. Prescribed burning (PB) is increasingly used in Europe as a practice to reduce fire risk, through dead fine fuel reduction. Several studies have focused on fire effects on vegetation and soil microbial community, but very few on ecosystem processes involved in water cycle. This study aims to estimate interception by the litter and fermentation layer and the successive evaporation flux in laboratory conditions, using a water balance and 2H and 18O isotopes mass balance calculation, in order to assess PB effects on the hydrology and ecosystem in pine plantations. PB was carried out in spring 2014 in three pine plantations of Southern Italy, dominated by Pinus halepensis (Cilento, Vallo di Diano e Alburni National Park, CVDANP), P. pinaster (Vesuvio National Park, VNP) and P. pinea (Castel Volturno Nature Reserve, CVNR). A dataset concerning the effects of PB on vegetation structure, floristic composition, microbial biomass and activity in the fermentation layer and 5-cm of soil beneath is available for the same stands. In each plantation, two cores of litter and fermentation layer were sampled in a burned area and in a near unburned area (control), respectively, with a collector to extract an "undisturbed" core. Then, each core was transferred in a lysimeter installed in the Water Lab of Delft University of Technology. In total, three lysimeters were set up and each experiment was carried out in duplicate. The laboratory had constant temperature, and both temperature and relative humidity were recorded every 15 minutes. To simulate rainfall, ~1 litre of tap water was sprinkled uniformly on the lysimeter with a plant spray (equivalent to 32 mm of rain). The precipitation was sprinkled every 3 days for a period of two months. Soil moisture and temperature were measured during the experiment every 15 minutes in the top and bottom of the litter and fermentation layer. Interception water was collected for isotope analysis from every layer with Rhizon soil moisture samplers by applying a vacuum with 5 ml syringes. Samples were collected two times per day (in the morning and in the evening) and at two different depths for each layer (~4 cm and ~7 cm in litter layer and ~10 and ~15 cm in fermentation layer) until 2 days after rain simulation. Water samples were analysed with laser spectrometry using the liquid water isotope analyser (LGR-LWIA). The influence of different litter layers and PB on interception and litter layer evaporation was assessed. Then, the evaporation flux measured using the lysimeter was compared with the calculated evaporation flux using the isotopes mass balance. Generally, the preliminary results indicate a slight increase in evaporation flux in burned areas compared to the controls, in P. pinea and P. pinaster stands. By contrast, in P. halepensis stand, a significant decrease in evaporation flux was detected in prescribed burned plot. The isotope mass balance method to measure litter evaporation is promising and could be used in future, in-situ, measurements of evaporation from the litter layer.

Early-stage changes in natural (13)C and (15)N abundance and nutrient dynamics during different litter decomposition.

PubMed

Gautam, Mukesh Kumar; Lee, Kwang-Sik; Song, Byeong-Yeol; Lee, Dongho; Bong, Yeon-Sik

2016-05-01

Decomposition, nutrient, and isotopic (δ(13)C and δ(15)N) dynamics during 1 year were studied for leaf and twig litters of Pinus densiflora, Castanea crenata, Erigeron annuus, and Miscanthus sinensis growing on a highly weathered soil with constrained nutrient supply using litterbags in a cool temperate region of South Korea. Decay constant (k/year) ranged from 0.58 to 1.29/year, and mass loss ranged from 22.36 to 58.43 % among litter types. The results demonstrate that mass loss and nutrient dynamics of decomposing litter were influenced by the seasonality of mineralization and immobilization processes. In general, most nutrients exhibited alternate phases of rapid mineralization followed by gradual immobilization, except K, which was released throughout the field incubation. At the end of study, among all the nutrients only N and P showed net immobilization. Mobility of different nutrients from decomposing litter as the percentage of initial litter nutrient concentration was in the order of K > Mg > Ca > N ≈ P. The δ(13)C (0.32-6.70 ‰) and δ(15)N (0.74-3.90 ‰) values of residual litters showed nonlinear increase and decrease, respectively compared to initial isotopic values during decomposition. Litter of different functional types and chemical quality converged toward a conservative nutrient use strategy through mechanisms of slow decomposition and slow nutrient mobilization. Our results indicate that litter quality and season, are the most important regulators of litter decomposition in these forests. The results revealed significant relationships between litter decomposition rates and N, C:N ratio and P, and seasonality (temperature). These results and the convergence of different litters towards conservative nutrient use in these nutrient constrained ecosystems imply optimization of litter management because litter removal can have cascading effects on litter decomposition and nutrient availability in these systems.

Climate change triggers effects of fungal pathogens and insect herbivores on litter decomposition

NASA Astrophysics Data System (ADS)

Butenschoen, Olaf; Scheu, Stefan

2014-10-01

Increasing infestation by insect herbivores and pathogenic fungi in response to climate change will inevitably impact the amount and quality of leaf litter inputs into the soil. However, little is known on the interactive effect of infestation severity and climate change on litter decomposition, and no such study has been published for deciduous forests in Central Europe. We assessed changes in initial chemical quality of beech (Fagus sylvatica L.) and maple litter (Acer platanoides L.) in response to infestation by the gall midge Mikiola fagi Hart. and the pathogenic fungus Sawadaea tulasnei Fuckel, respectively, and investigated interactive effects of infestation severity, changes in temperature and soil moisture on carbon mineralization in a short-term laboratory study. We found that infestation by the gall midge M. fagi and the pathogenic fungus S. tulasnei significantly changed the chemical quality of beech and maple litter. Changes in element concentrations were generally positive and more pronounced, and if negative less pronounced for maple than beech litter most likely due to high quality fungal tissue remaining on litter after abscission. More importantly, alterations in litter chemical quality did not translate to distinct patterns of carbon mineralization at ambient conditions, but even low amounts of infested litter accelerated carbon mineralization at moderately increased soil moisture and in particular at higher temperature. Our results indicate that insect herbivores and fungal pathogens can markedly alter initial litter chemical quality, but that afterlife effects on carbon mineralization depend on soil moisture and temperature, suggesting that increased infestation severity under projected climate change potentially increases soil carbon release in deciduous forests in Central Europe.

Influence of invasive earthworm activity on carbon dynamics in soils from the Aspen Free Air CO2 Enrichment Experiment

NASA Astrophysics Data System (ADS)

Filley, T. R.; Top, S. M.; Hopkins, F. M.

2010-12-01

The influence of CO2-driven increase in net primary productivity on soil organic carbon accrual has received considerable emphasis in ecological literature with conclusions varying from positive, to neutral, to negative. What has been understudied is the coupled role of soil fauna, such as earthworms, in controlling the ultimate fate of new above and below ground plant carbon under elevated CO2. Such considerations are particularly relevant considering that in most northern North American forests earthworms are an exotic organism known to cause significant changes to forest floor chemistry and soil structure, possibly increasing nutrient loss from both soil and leaf litter and mixing litter and humus deep into the mineral soil. The impact of these exotic earthworms on overall soil carbon stabilization is largely unknown but likely a function of both species composition and edaphic soil properties. In this paper we present the initial results of a carbon isotope study (13C, 14C) conducted at the Aspen free air CO2 enrichment (FACE) site, Rhinelander, WI, USA to track allocation and redistribution within the soil of plant litter and root carbon (bulk and biopolymer). Along with litter and soil to 25 cm depth, earthworm populations were quantified, and their gut contents collected for isotopic and plant biopolymer chemistry analysis. Contributions of root vs. leaf input to soil and earthworm fecal matter were derived from differences in the chemical and isotope composition of alkaline CuO-derived lignin and substituted fatty acids (SFA) from cutin and suberin. Our investigation demonstrates the presence of invasive European earthworms, of both litter and surface soil dwelling (epigeic) and deep soil dwelling (endogeic) varieties, whose abundance increases under elevated CO2 conditions. Additionally, the different species show selective vertical movement of new and pre-FACE plant biopolymers indicating dynamics in root and leaf decomposition and burial (down to 30 cm) based upon exotic earthworm activity. The isotopic analysis also demonstrates that these invasive ecosystem engineers are bringing up “old” pre-FACE carbon to the surface, diluting the surface soil carbon isotope signature and potentially causing an apparent “slowing” of the rate of accumulation of FACE derived carbon. Our results highlight the complexity of determining soil C dynamics and the important role of invertebrate ecology in this process.

Input-decomposition balance of heterotrophic processes in a warm-temperate mixed forest in Japan

NASA Astrophysics Data System (ADS)

Jomura, M.; Kominami, Y.; Ataka, M.; Makita, N.; Dannoura, M.; Miyama, T.; Tamai, K.; Goto, Y.; Sakurai, S.

2010-12-01

Carbon accumulation in forest ecosystem has been evaluated using three approaches. One is net ecosystem exchange (NEE) estimated by tower flux measurement. The second is net ecosystem production (NEP) estimated by biometric measurements. NEP can be expressed as the difference between net primary production and heterotrophic respiration. NEP can also be expressed as the annual increment in the plant biomass (ΔW) plus soil (ΔS) carbon pools defined as follows; NEP = ΔW+ΔS The third approach needs to evaluate annual carbon increment in soil compartment. Soil carbon accumulation rate could not be measured directly in a short term because of the small amount of annual accumulation. Soil carbon accumulation rate can be estimated by a model calculation. Rothamsted carbon model is a soil organic carbon turnover model and a useful tool to estimate the rate of soil carbon accumulation. However, the model has not sufficiently included variations in decomposition processes of organic matters in forest ecosystems. Organic matter in forest ecosystems have a different turnover rate that creates temporal variations in input-decomposition balance and also have a large variation in spatial distribution. Thus, in order to estimate the rate of soil carbon accumulation, temporal and spatial variation in input-decomposition balance of heterotrophic processes should be incorporated in the model. In this study, we estimated input-decomposition balance and the rate of soil carbon accumulation using the modified Roth-C model. We measured respiration rate of many types of organic matters, such as leaf litter, fine root litter, twigs and coarse woody debris using a chamber method. We can illustrate the relation of respiration rate to diameter of organic matters. Leaf and fine root litters have no diameter, so assumed to be zero in diameter. Organic matters in small size, such as leaf and fine root litter, have high decomposition respiration. It could be caused by the difference in structure of organic matter. Because coarse woody debris has shape of cylinder, microbes decompose from the surface of it. Thus, respiration rate of coarse woody debris is lower than that of leaf and fine root litter. Based on this result, we modified Roth-C model and estimate soil carbon accumulation rate in recent years. Based on the results from a soil survey, the forest soil stored 30tC ha-1 in O and A horizon. We can evaluate the modified model using this result. NEP can be expressed as the annual increment in the plant biomass plus soil carbon pools. So if we can estimate NEP using this approach, then we can evaluate NEP estimated by micrometeorological and ecological approaches and reduce uncertainty of NEP estimation.

Winter litter disturbance facilitates the spread of the nonnative invasive grass Microstegium vimineum (Trin.) A. Camus

Treesearch

Christopher M. Oswalt; Sonja N. Oswalt

2007-01-01

We investigated the impacts of winter litter disturbance on the spread of the nonnative invasive plant Microstegium vimineum (Trin.) A. Camus through experimental removals. We hypothesized that light penetration through the litter layer facilitates the spread of M. vimineum in forested systems. Our objective, therefore, was to...

Uncovering Wildlife

ERIC Educational Resources Information Center

Travis, Holly

2016-01-01

Many ground-dwelling amphibians, reptiles, small mammals, insects, and other arthropods seek cover during their resting hours. Their natural hideaways include underground burrows, rotting logs, and leaf litter, which are widely distributed and difficult to discover and observe. To make observation easier, scientists, educators, and students can…

RESPONSE OF NUTRIENTS, BIOFILM, AND BENTHIC INSECTS TO SALMON CARCASS ADDITION

EPA Science Inventory

Salmon carcass addition to streams is expected to increase stream productivity at multiple trophic levels. This study examined stream nutrient (nitrogen, phosphorus, and carbon), epilithic biofilm (ash-free dry mass and chlorophyll a), leaf-litter decomposition, and macroinverte...

Leaf Litter Decomposition as a Functional Assessment of a Natural Stream Channel Design Project

NASA Astrophysics Data System (ADS)

Gentry, A.; Word, D.; Carreiro, M.; Jack, J.

2005-05-01

In October 2003, a 965m reach of Wilson Creek (Bernheim Research Forest, Kentucky, USA) was relocated, and meanders and riffle-pool sequences were restored, providing a unique opportunity to measure the re-establishment of post-restoration stream functions. Leaf litter bags were placed across riffles in the restored reach, in an upstream reference site and in two reference streams. Bags were collected for nine months, and mass loss, N dynamics and fungal ergosterol were measured. Daily mass loss rates in the restored and reference riffles in Wilson Creek were faster (k= -0.00759 and k= -0.00855, respectively) than those of the two reference streams (k= -0.00511 and k= -0.00308). This is equivalent to litter mean residence times of 132 days for the restored reach in Wilson, 117 days in the upstream reference site, and 196 and 325 days for the reference streams. It appears that the decay rate in the restored reach is similar to the upstream portion of Wilson Creek, indicating rapid mass loss recovery in the restored reach. We also determined that same-stream reference sites are important for evaluating the restoration of stream functions, because of high decay rate variation among nearby streams within the same watershed.

Characterizing Dissolved Organic Matter (DOM) Isolated From Specific Allochthonous and Autochthonous Sources in a North-Temperate Stream Ecosystem

NASA Astrophysics Data System (ADS)

Wong, J. C.; Williams, D.

2009-05-01

Detrital energy in temperate headwater streams is mainly derived from the annual input of leaf litter from the surrounding landscape. Presumably, its decomposition and other sources of autochthonous organic matter will change dissolved organic carbon (DOC) concentrations and dissolved organic matter (DOM) quality. To investigate this, DOM was leached from two allochthonous sources: white birch (Betula papyrifera) and white cedar (Thuja occidentalis); and one autochthonous source, streambed biofilm, for a period of 7 days on 3 separate occasions in fall 2007. As a second treatment, microorganisms from the water column were filtered out. Deciduous leaf litter was responsible for high, short-term increases to DOC concentrations whereas the amounts leached from conifer needles were relatively constant in each month. Using UV spectroscopy, changes to DOM characteristics like aromaticity, spectral slopes, and molecular weight were mainly determined by source and indicated a preferential use of the labile DOM pool by the microorganisms. Excitation-emission matrices (EEMs) collected using fluorescence spectroscopy suggested that cedar litter was an important source of protein-like fluorescence and that the nature of the fluorescing DOM components changed in the presence of microorganisms. This study demonstrates that simultaneous examination of DOC concentrations and DOM quality will allow a better understanding of the carbon dynamics that connect terrestrial with aquatic ecosystems.

Diversity, taxonomic composition, and functional aspects of fungal communities in living, senesced, and fallen leaves at five sites across North America

PubMed Central

Arnold, A. Elizabeth

2016-01-01

Background Fungal endophytes inhabit symptomless, living tissues of all major plant lineages to form one of earth’s most prevalent groups of symbionts. Many reproduce from senesced and/or decomposing leaves and can produce extracellular leaf-degrading enzymes, blurring the line between symbiotrophy and saprotrophy. To better understand the endophyte–saprotroph continuum we compared fungal communities and functional traits of focal strains isolated from living leaves to those isolated from leaves after senescence and decomposition, with a focus on foliage of woody plants in five biogeographic provinces ranging from tundra to subtropical scrub forest. Methods We cultured fungi from the interior of surface-sterilized leaves that were living at the time of sampling (i.e., endophytes), leaves that were dead and were retained in plant canopies (dead leaf fungi, DLF), and fallen leaves (leaf litter fungi, LLF) from 3–4 species of woody plants in each of five sites in North America. Our sampling encompassed 18 plant species representing two families of Pinophyta and five families of Angiospermae. Diversity and composition of fungal communities within and among leaf life stages, hosts, and sites were compared using ITS-partial LSU rDNA data. We evaluated substrate use and enzyme activity by a subset of fungi isolated only from living tissues vs. fungi isolated only from non-living leaves. Results Across the diverse biomes and plant taxa surveyed here, culturable fungi from living leaves were isolated less frequently and were less diverse than those isolated from non-living leaves. Fungal communities in living leaves also differed detectably in composition from communities in dead leaves and leaf litter within focal sites and host taxa, regardless of differential weighting of rare and abundant fungi. All focal isolates grew on cellulose, lignin, and pectin as sole carbon sources, but none displayed ligninolytic or pectinolytic activity in vitro. Cellulolytic activity differed among fungal classes. Within Dothideomycetes, activity differed significantly between fungi from living vs. non-living leaves, but such differences were not observed in Sordariomycetes. Discussion Although some fungi with endophytic life stages clearly persist for periods of time in leaves after senescence and incorporation into leaf litter, our sampling across diverse biomes and host lineages detected consistent differences between fungal assemblages in living vs. non-living leaves, reflecting incursion by fungi from the leaf exterior after leaf death and as leaves begin to decompose. However, fungi found only in living leaves do not differ consistently in cellulolytic activity from those fungi detected thus far only in dead leaves. Future analyses should consider Basidiomycota in addition to the Ascomycota fungi evaluated here, and should explore more dimensions of functional traits and persistence to further define the endophytism-to-saprotrophy continuum. PMID:27994976

Diversity, taxonomic composition, and functional aspects of fungal communities in living, senesced, and fallen leaves at five sites across North America.

PubMed

U'Ren, Jana M; Arnold, A Elizabeth

2016-01-01

Fungal endophytes inhabit symptomless, living tissues of all major plant lineages to form one of earth's most prevalent groups of symbionts. Many reproduce from senesced and/or decomposing leaves and can produce extracellular leaf-degrading enzymes, blurring the line between symbiotrophy and saprotrophy. To better understand the endophyte-saprotroph continuum we compared fungal communities and functional traits of focal strains isolated from living leaves to those isolated from leaves after senescence and decomposition, with a focus on foliage of woody plants in five biogeographic provinces ranging from tundra to subtropical scrub forest. We cultured fungi from the interior of surface-sterilized leaves that were living at the time of sampling (i.e., endophytes), leaves that were dead and were retained in plant canopies (dead leaf fungi, DLF), and fallen leaves (leaf litter fungi, LLF) from 3-4 species of woody plants in each of five sites in North America. Our sampling encompassed 18 plant species representing two families of Pinophyta and five families of Angiospermae. Diversity and composition of fungal communities within and among leaf life stages, hosts, and sites were compared using ITS-partial LSU rDNA data. We evaluated substrate use and enzyme activity by a subset of fungi isolated only from living tissues vs. fungi isolated only from non-living leaves. Across the diverse biomes and plant taxa surveyed here, culturable fungi from living leaves were isolated less frequently and were less diverse than those isolated from non-living leaves. Fungal communities in living leaves also differed detectably in composition from communities in dead leaves and leaf litter within focal sites and host taxa, regardless of differential weighting of rare and abundant fungi. All focal isolates grew on cellulose, lignin, and pectin as sole carbon sources, but none displayed ligninolytic or pectinolytic activity in vitro . Cellulolytic activity differed among fungal classes. Within Dothideomycetes, activity differed significantly between fungi from living vs. non-living leaves, but such differences were not observed in Sordariomycetes. Although some fungi with endophytic life stages clearly persist for periods of time in leaves after senescence and incorporation into leaf litter, our sampling across diverse biomes and host lineages detected consistent differences between fungal assemblages in living vs. non-living leaves, reflecting incursion by fungi from the leaf exterior after leaf death and as leaves begin to decompose. However, fungi found only in living leaves do not differ consistently in cellulolytic activity from those fungi detected thus far only in dead leaves. Future analyses should consider Basidiomycota in addition to the Ascomycota fungi evaluated here, and should explore more dimensions of functional traits and persistence to further define the endophytism-to-saprotrophy continuum.

Measuring microbial fitness in a field reciprocal transplant experiment.

PubMed

Boynton, Primrose J; Stelkens, Rike; Kowallik, Vienna; Greig, Duncan

2017-05-01

Microbial fitness is easy to measure in the laboratory, but difficult to measure in the field. Laboratory fitness assays make use of controlled conditions and genetically modified organisms, neither of which are available in the field. Among other applications, fitness assays can help researchers detect adaptation to different habitats or locations. We designed a competitive fitness assay to detect adaptation of Saccharomyces paradoxus isolates to the habitat they were isolated from (oak or larch leaf litter). The assay accurately measures relative fitness by tracking genotype frequency changes in the field using digital droplet PCR (DDPCR). We expected locally adapted S. paradoxus strains to increase in frequency over time when growing on the leaf litter type from which they were isolated. The DDPCR assay successfully detected fitness differences among S. paradoxus strains, but did not find a tendency for strains to be adapted to the habitat they were isolated from. Instead, we found that the natural alleles of the hexose transport gene we used to distinguish S. paradoxus strains had significant effects on fitness. The origin of a strain also affected its fitness: strains isolated from oak litter were generally fitter than strains from larch litter. Our results suggest that dispersal limitation and genetic drift shape S. paradoxus populations in the forest more than local selection does, although further research is needed to confirm this. Tracking genotype frequency changes using DDPCR is a practical and accurate microbial fitness assay for natural environments. © 2016 The Authors. Molecular Ecology Resources Published by John Wiley & Sons Ltd.

Catalogue of snout mites (Acariformes: Bdellidae) of the world

USDA-ARS?s Scientific Manuscript database

Bdellidae (Trombidiformes: Prostigmata) are moderate to large sized predatory mites that inhabit soil, leaves, leaf litter, and intertidal rocks. They are readily recognized by an elongated, snout-like gnathosoma and by elbowed pedipalps bearing two (one in Monotrichobdella) long terminal setae. Des...

Composition of riparian litter input regulates organic matter decomposition: Implications for headwater stream functioning in a managed forest landscape.

PubMed

Lidman, Johan; Jonsson, Micael; Burrows, Ryan M; Bundschuh, Mirco; Sponseller, Ryan A

2017-02-01

Although the importance of stream condition for leaf litter decomposition has been extensively studied, little is known about how processing rates change in response to altered riparian vegetation community composition. We investigated patterns of plant litter input and decomposition across 20 boreal headwater streams that varied in proportions of riparian deciduous and coniferous trees. We measured a suite of in-stream physical and chemical characteristics, as well as the amount and type of litter inputs from riparian vegetation, and related these to decomposition rates of native (alder, birch, and spruce) and introduced (lodgepole pine) litter species incubated in coarse- and fine-mesh bags. Total litter inputs ranged more than fivefold among sites and increased with the proportion of deciduous vegetation in the riparian zone. In line with differences in initial litter quality, mean decomposition rate was highest for alder, followed by birch, spruce, and lodgepole pine (12, 55, and 68% lower rates, respectively). Further, these rates were greater in coarse-mesh bags that allow colonization by macroinvertebrates. Variance in decomposition rate among sites for different species was best explained by different sets of environmental conditions, but litter-input composition (i.e., quality) was overall highly important. On average, native litter decomposed faster in sites with higher-quality litter input and (with the exception of spruce) higher concentrations of dissolved nutrients and open canopies. By contrast, lodgepole pine decomposed more rapidly in sites receiving lower-quality litter inputs. Birch litter decomposition rate in coarse-mesh bags was best predicted by the same environmental variables as in fine-mesh bags, with additional positive influences of macroinvertebrate species richness. Hence, to facilitate energy turnover in boreal headwaters, forest management with focus on conifer production should aim at increasing the presence of native deciduous trees along streams, as they promote conditions that favor higher decomposition rates of terrestrial plant litter.

Investigating organic matter in Fanno Creek, Oregon, Part 1 of 3: estimating annual foliar biomass for a deciduous-dominant urban riparian corridor

USGS Publications Warehouse

Sobieszczyk, Steven; Keith, Mackenzie K.; Rounds, Stewart A.; Goldman, Jami H.

2014-01-01

For this study, we explored the amount, type, and distribution of foliar biomass that is deposited annually as leaf litter to Fanno Creek and its floodplain in Portland, Oregon, USA. Organic matter is a significant contributor to the decreased dissolved oxygen concentrations observed in Fanno Creek each year and leaf litter is amongst the largest sources of organic matter to the stream channel and floodplain. Using a combination of field measurements and light detection and ranging (LiDAR) point cloud data, the annual foliar biomass was estimated for 13 stream reaches along the creek. Biomass estimates were divided into two sets: (1) the annual foliage available from the entire floodplain overstory canopy, and (2) the annual foliage overhanging the stream, which likely contributes leaf litter directly to the creek each year. Based on these computations, an estimated 991 (±22%) metric tons (tonnes, t) of foliar biomass is produced annually above the floodplain, with about 136 t (±24%) of that foliage falling directly into Fanno Creek. The distribution of foliar biomass varies by reach, with between 150 and 640 t/km2 produced along the floodplain and between 400 and 1100 t/km2 available over the channel. Biomass estimates vary by reach based primarily on the density of tree cover, with forest-dominant reaches containing more mature deciduous trees with broader tree canopies than either wetland or urban-dominant reaches, thus supplying more organic material to the creek. By quantifying the foliar biomass along Fanno Creek we have provided a reach-scale assessment of terrestrial organic matter loading, thereby providing land managers useful information for planning future restoration efforts.

Investigating organic matter in Fanno Creek, Oregon, Part 1 of 3: Estimating annual foliar biomass for a deciduous-dominant urban riparian corridor

NASA Astrophysics Data System (ADS)

Sobieszczyk, Steven; Keith, Mackenzie K.; Rounds, Stewart A.; Goldman, Jami H.

2014-11-01

For this study, we explored the amount, type, and distribution of foliar biomass that is deposited annually as leaf litter to Fanno Creek and its floodplain in Portland, Oregon, USA. Organic matter is a significant contributor to the decreased dissolved oxygen concentrations observed in Fanno Creek each year and leaf litter is amongst the largest sources of organic matter to the stream channel and floodplain. Using a combination of field measurements and light detection and ranging (LiDAR) point cloud data, the annual foliar biomass was estimated for 13 stream reaches along the creek. Biomass estimates were divided into two sets: (1) the annual foliage available from the entire floodplain overstory canopy, and (2) the annual foliage overhanging the stream, which likely contributes leaf litter directly to the creek each year. Based on these computations, an estimated 991 (±22%) metric tons (tonnes, t) of foliar biomass is produced annually above the floodplain, with about 136 t (±24%) of that foliage falling directly into Fanno Creek. The distribution of foliar biomass varies by reach, with between 150 and 640 t/km2 produced along the floodplain and between 400 and 1100 t/km2 available over the channel. Biomass estimates vary by reach based primarily on the density of tree cover, with forest-dominant reaches containing more mature deciduous trees with broader tree canopies than either wetland or urban-dominant reaches, thus supplying more organic material to the creek. By quantifying the foliar biomass along Fanno Creek we have provided a reach-scale assessment of terrestrial organic matter loading, thereby providing land managers useful information for planning future restoration efforts.

Spurious and functional correlates of the isotopic composition of a generalist across a tropical rainforest landscape

PubMed Central

2009-01-01

Background The isotopic composition of generalist consumers may be expected to vary in space as a consequence of spatial heterogeneity in isotope ratios, the abundance of resources, and competition. We aim to account for the spatial variation in the carbon and nitrogen isotopic composition of a generalized predatory species across a 500 ha. tropical rain forest landscape. We test competing models to account for relative influence of resources and competitors to the carbon and nitrogen isotopic enrichment of gypsy ants (Aphaenogaster araneoides), taking into account site-specific differences in baseline isotope ratios. Results We found that 75% of the variance in the fraction of 15N in the tissue of A. araneoides was accounted by one environmental parameter, the concentration of soil phosphorus. After taking into account landscape-scale variation in baseline resources, the most parsimonious model indicated that colony growth and leaf litter biomass accounted for nearly all of the variance in the δ15N discrimination factor, whereas the δ13C discrimination factor was most parsimoniously associated with colony size and the rate of leaf litter decomposition. There was no indication that competitor density or diversity accounted for spatial differences in the isotopic composition of gypsy ants. Conclusion Across a 500 ha. landscape, soil phosphorus accounted for spatial variation in baseline nitrogen isotope ratios. The δ15N discrimination factor of a higher order consumer in this food web was structured by bottom-up influences - the quantity and decomposition rate of leaf litter. Stable isotope studies on the trophic biology of consumers may benefit from explicit spatial design to account for edaphic properties that alter the baseline at fine spatial grains. PMID:19930701

Feeding group responses of a Neotropical termite assemblage to rain forest fragmentation.

PubMed

Davies, Richard G

2002-10-01

Biomass collapse and its associated microclimatic stresses within recently isolated rain forest fragments may negatively affect species diversity of most resident taxa. However, for some decomposer organisms, increased resource availability via accompanying tree die-off may effect positive responses, at least for a time, with implications for rates of nutrient cycling and greenhouse gas release. This study investigates the early effects of forest fragmentation on a Neotropical termite assemblage. Numbers of encounters (surrogate for relative abundance) and species richness of wood and leaf-litter feeders, soil feeders, and the whole assemblage, were studied across true forest islands and mainland sites at a hydroelectric reservoir in French Guiana. Results showed no overall effect of fragmentation on either total termite encounters or species richness. However, numbers of encounters and species richness of wood and leaf-litter feeders showed positive responses to forest fragmentation. By contrast, soil feeders showed a negative response for numbers of encounters and no significant effect for species richness. Environmental data suggest that increased tree die-off, and other edge effects associated with biomass collapse, were underway at the time of sampling. Resulting increase in resource availability may therefore explain the positive influence on wood and leaf-litter feeders. A possible decrease in predation pressure from ants with decrease in island size was not tested for, but was a likely effect of the flooded matrix habitat. Fragmentation effects on soil feeder encounters may be due to the energetic and microclimatic constraints of feeding lower down the humification gradient of termite food substrates, but were not sufficient to affect species richness. The patterns revealed suggest that rates of wood decomposition following tree die-off, and of soil nutrient cycling, under different rain forest fragmentation scenarios, merit further study.

Optical Characterization and Bioavailability of Dissolved Organic Matter of Leaf Leachates from Restored and Forested Delmarva Bay Catchments

NASA Astrophysics Data System (ADS)

Reed, E.; Armstrong, A.

2016-12-01

The optical properties and lability of fresh leaf and litter leachates obtained from Delmarva wetlands were analyzed to gain a further understanding of the carbon inputs and outputs of that wetland system. Carbon entering the wetland system may be digested by microbes and then given off as either carbon dioxide or methane, both of which enter the atmosphere as greenhouse gases. Delmarva Bays are often considered geographically isolated and only have surface water present in certain times of year. The vegetation around the wetlands are assumed to be a major input of the dissolved organic matter (DOM) in the wetland surface water. An understanding of the sources and lability of wetland water DOM can lead to further insight into the connections between vegetation, wetland management, and carbon cycling. Two paired wetland sites were sampled in this study, each included a forested catchment and a prior-converted agricultural wetland that had undergone hydrological ecosystem restoration. Leaf samples of Liquidambar styraciflua, Acer rubrum, Nyssa sylvatica, Polygonum, and Typha were taken directly from the living plant or from surrounding ground as litter. Spectral properties of the leachates were determined from fluorescence and absorbance, including PARAFAC components, fluorescence index (FI), humification index (HI), and the specific ultraviolet absorbance (SUVA). Leachates were also incubated with microbes taken from Tuckahoe Creek, a stream to which all sampled sites eventually drain, to determine the bioavailability of the carbon. There were measurable differences found between samples obtained from leaves and litter, as well as a difference between the herbaceous and tree samples. The results obtained from this study can help create more accurate models of how carbon cycles through these wetlands, both in forested and restored environments.

The effect of latitudinal gradient on the species diversity of Chinese litter-dwelling thrips

PubMed Central

Wang, Jun; Tong, Xiaoli; Wu, Donghui

2014-01-01

Abstract To understand the global distribution patterns of litter-dwelling thrips, a total 150 leaf litter samples were collected from 6 natural reserves located in three climatic regions, temperate, subtropical and tropical. The results showed the relative abundance of Thysanoptera was over 3.0% in 4 natural reserves from subtropical and tropical zone, and reached 5.9% in one tropical reserve, only less than Acarina and Collembola. In contrast it was only 0.3% in the warm temperate natural reserves, and no thrips were collected in a mid temperate reserve. The order on the average species numbers per plot of litter thrips was tropic > subtropics > temperate (n=25, p<0.05). Mean density of litter thrips per plots in the tropics and subtropics was significantly higher than that in the temperate region (n=25, p<0.05), but the average density was not significantly different between tropical and subtropical zones (n=25, p>0.05). The diversity of litter thrips in the tropics and subtropics was much higher than that in the temperate area based on comparsions of Shannon-Wiener diversity index (H’), Pielou eveness index (J), and Simpson dominance index (D). All of these results indicated that litter-dwelling thrips lived mainly in tropical and subtropical regions; meanwhile, species number and relative abundance increased with decreasing latitude. PMID:25061351

Can visible light impact litter decomposition under pollution of ZnO nanoparticles?

PubMed

Du, Jingjing; Zhang, Yuyan; Liu, Lina; Qv, Mingxiang; Lv, Yanna; Yin, Yifei; Zhou, Yinfei; Cui, Minghui; Zhu, Yanfeng; Zhang, Hongzhong

2017-11-01

ZnO nanoparticles is one of the most used materials in a wide range including antibacterial coating, electronic device, and personal care products. With the development of nanotechnology, ecotoxicology of ZnO nanoparticles has been received increasing attention. To assess the phototoxicity of ZnO nanoparticles in aquatic ecosystem, microcosm experiments were conducted on Populus nigra L. leaf litter decomposition under combined effect of ZnO nanoparticles and visible light radiation. Litter decomposition rate, pH value, extracellular enzyme activity, as well as the relative contributions of fungal community to litter decomposition were studied. Results showed that long-term exposure to ZnO nanoparticles and visible light led to a significant decrease in litter decomposition rate (0.26 m -1 vs 0.45 m -1 ), and visible light would increase the inhibitory effect (0.24 m -1 ), which caused significant decrease in pH value of litter cultures, fungal sporulation rate, as well as most extracellular enzyme activities. The phototoxicity of ZnO nanoparticles also showed impacts on fungal community composition, especially on the genus of Varicosporium, whose abundance was significantly and positively related to decomposition rate. In conclusion, our study provides the evidence for negatively effects of ZnO NPs photocatalysis on ecological process of litter decomposition and highlights the contribution of visible light radiation to nanoparticles toxicity in freshwater ecosystems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Shifts in microbial community structure and function in stream sediments during experimentally simulated riparian succession.

PubMed

Frossard, Aline; Gerull, Linda; Mutz, Michael; Gessner, Mark O

2013-05-01

Successional changes of terrestrial vegetation can profoundly influence stream ecosystem structure and function. We hypothesized that microbial enzyme production and community structure in stream beds depend on terrestrial litter inputs that reflect different stages of riparian succession. Outdoor experimental channels were supplied with leaf-litter of varying quantities and qualities to mimic litter supply during five successional stages: (1) an initial biofilm stage; (2) an open-land stage with grass litter; (3) a transitional stage with mixed grass and birch litter; (4) an early forest stage with birch litter; and (5) an advanced forest stage with 2.5 × the amount of birch litter. Mean potential activities of nitrogen- and phosphorus-acquiring enzymes in sediments (20.7 and 67.3 μmol g(-1) dry mass) were 12-70 times greater than those of carbon-acquiring enzymes (0.96-1.71 μmol g(-1) dry mass), with the former reduced 1.3-8.3-fold in channels with tree litter. These patterns could suggest gradually diminishing nutrient limitation of microbial activity during riparian succession, potentially linked both to an increasing supply by the added litter and to a lower nutrient demand as algal biomass and labile carbon supply by photosynthetic exudates declined. As the observed shifts in nutrient-acquiring enzymes were reflected in changes of sediment microbial communities, these results indicate that both the type and density of terrestrial vegetation control microbial community structure and function in stream sediments, particularly enzyme production related to nutrient cycling. © 2013 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Environmental safety to decomposer invertebrates of azadirachtin (neem) as a systemic insecticide in trees to control emerald ash borer.

PubMed

Kreutzweiser, David; Thompson, Dean; Grimalt, Susana; Chartrand, Derek; Good, Kevin; Scarr, Taylor

2011-09-01

The non-target effects of an azadirachtin-based systemic insecticide used for control of wood-boring insect pests in trees were assessed on litter-dwelling earthworms, leaf-shredding aquatic insects, and microbial communities in terrestrial and aquatic microcosms. The insecticide was injected into the trunks of ash trees at a rate of 0.2 gazadirachtin cm(-1) tree diameter in early summer. At the time of senescence, foliar concentrations in most (65%) leaves where at or below detection (<0.01 mg kg(-1) total azadirachtin) and the average concentration among leaves overall at senescence was 0.19 mg kg(-1). Leaves from the azadirachtin-treated trees at senescence were added to microcosms and responses by test organisms were compared to those in microcosms containing leaves from non-treated ash trees (controls). No significant reductions were detected among earthworm survival, leaf consumption rates, growth rates, or cocoon production, aquatic insect survival and leaf consumption rates, and among terrestrial and aquatic microbial decomposition of leaf material in comparison to controls. In a further set of microcosm tests containing leaves from intentional high-dose trees, the only significant, adverse effect detected was a reduction in microbial decomposition of leaf material, and only at the highest test concentration (∼6 mg kg(-1)). Results indicated no significant adverse effects on litter-dwelling earthworms or leaf-shredding aquatic insects at concentrations up to at least 30 × the expected field concentrations at operational rates, and at 6 × expected field concentrations for adverse effects on microbial decomposition. We conclude that when azadirachtin is used as a systemic insecticide in trees for control of insect pests such as the invasive wood-boring beetle, emerald ash borer, resultant foliar concentrations in senescent leaf material are likely to pose little risk of harm to decomposer invertebrates. Crown Copyright © 2011. Published by Elsevier Inc. All rights reserved.

Seasonal Variations in Ash Content of Some Michigan Forest Floor Fuels

Treesearch

Robert M. Loomis

1982-01-01

Samples from the forest floor litter layer were collected seasonally from under medium to fully stocked larger sapling to sawtimber stands in Lower Michigan to study seasonal ash content changes. The total ash and silica-free ash content of tree foliage in the upper part of the litter layer differed little from season to season. Differences in ash content due to...

Isotopic Discrimination During Leaf Litter Decomposition

NASA Astrophysics Data System (ADS)

Ngao, J.; Rubino, M.

2006-12-01

Methods involving stable isotopes have been successfully applied since decades in various research fields. Tracing 13C natural abundance in ecosystem compartments greatly enhanced the understanding of the C fluxes in the plant-soil-atmosphere C exchanges when compartments present different C isotopic signatures (i.e. atmospheric CO2 vs photosynthetic leaves, C3 vs C4; etc.). However, the assumption that no isotopic discrimination occurs during respiration is commonly made in numbers of C isotope-based ecological studies. Furthermore, verifications of such assumption are sparse and not enough reliable. The aim of our study is to assess the potential isotopic discrimination that may occur during litter decomposition. Leaf litter from an Arbutus unedo (L.) stand (Tolfa, Italy) was incubated in 1L jars, under constant laboratory conditions (i.e. 25 ° C and 135% WC). During the entire incubation period, gravimetric mass loss, litter respiration rates and the isotopic composition of respired CO2 are monitored at regular intervals. Data from 7 months of incubation will be presented and discussed. After two months, the litter mass loss averaged 16% of initial dry mass. During the same time-period, the respiration rate decreased significantly by 58% of the initial respiration rate. Isotopic compositions of respired CO2 ranged between -27.95‰ and - 25.69‰. Mean values did not differ significantly among the sampling days, in spite of an apparent enrichment in 13C of respired CO2 with time. The significance of these isotopic enrichment will be determined at a longer time scale. They may reveal both/either a direct microbial discrimination during respiration processes and/or a use of different litter compounds as C source along time. Further chemical and compound-specific isotopic analysis of dry matter will be performed in order to clarify these hypotheses. This work is part of the "ALICE" project, funded by the European Union's Marie Curie Fellowship Actions that aims to implement an advanced laser spectrometry technology to measure the isotopic composition in respired CO2. The laser spectrometer will be used to investigate the isotopic discrimination during soil respiration, in laboratory and field studies.

Metaproteomics to investigate the impact of sampling-site biogeochemistry on structure and functionality of leaf-litter degrading microbial communities

NASA Astrophysics Data System (ADS)

Schneider, Thomas; Keiblinger, Katharina; Gerrits, Bertran; Schmid, Emanuel; Eberl, Leo; Zechmeister-Boltenstern, Sophie; Riedel, Kathrin

2010-05-01

The composition of organic matter in natural ecosystems is strongly influenced by the microorganisms present. Conversely, bacteria and fungi are limited by the amount and type of organic matter available in a given environment, most of which is ultimately derived from plants. Changes in the stoichiometry and biochemical constituents of plant litter may therefore alter species composition and elicit changes in the activities of microbial communities and their component parts. The identification of the microbial proteins of a given habitat together with the analysis of their phylogenetic origin and their spatial and temporal distribution are expected to provide fundamentally new insights into the role of microbial diversity in biogeochemical processes. To relate structure and functionality of microbial communities involved in leaf-litter decomposition we determined biogeochemistry, community structure by phospholipid fatty acid (PLFA)-analyses, enzymatic activities, and analysed the protein complement of different litter types, which were collected in winter and spring at various Austrian sampling sites, in a semi-quantitative proteomics approach by one dimensional polyacrylamide gel electrophoresis (1-D-SDS-PAGE) combined with liquid chromatography/tandem mass-spectrometry (LC-MS/MS). Protein abundances were determined by counting the number of MS/MS spectra assigned to each protein. In samples with high manganese and phosphor content a significant increase of fungal proteins from February to May was observed, which was in good agreement with the PLFA-analyses showing similar trends towards an increase of the fungal community. In contrast, the PLFA analysis revealed no temporal changes in the community at Achenkirch and even a decrease in the fungal/bacterial ratio at Klausen-Leopoldsdorf, two sampling sites low in P and Mn; similar trends are reflected in our spectral counts. In conclusion, semi-quantitative proteome- and PLFA-analyses suggest that fungal and bacterial abundance positively correlates with the total amount of P and Mn within the different litter types. Spectral counts of extracellular enzymes demonstrated a significant increase of these enzymes in the May, which was also mirrored by measurements of total enzymatic activities. The finding that almost all hydrolytic enzymes identified from litter were of fungal origin suggests a prominent role of fungi during aerobic litter decomposition.

A new genus of Neotropical Monoplatina (Coleoptera: Chrysomelidae: Galerucinae: Alticini) from leaf litter

USDA-ARS?s Scientific Manuscript database

A new genus (Andersonaltica) containing four new species from Central America is described and illustrated. It is compared to Aedmon Clark, Apleuraltica Bechyne, Distigmoptera Blake, Hypolampsis Clark, and Pseudolampsis Horn and a key to identification of these genera is provided...

The Combined Role Of Manganese Oxides And Microbes In The yAbiotic Uptake Of Amino Acid Nitrogen Into Litter And Soil Organic yMatter

NASA Astrophysics Data System (ADS)

Filley, T. R.; Dria, K.

2004-12-01

Soil organic matter (SOM) is the largest terrestrial C and N store. Microbial yand abiotic processes that control the transformation of protein nitrogen in litter and ysoils into macromolecular humic materials play an important role in organic matter ystorage and soil productivity. There are major gaps, however, in our understanding of ythese processes and behaviors. Abiotic reactions of amines, phenols and sugars derived yfrom forest leachates or present in detrital and litter organic matter are known to be ykey processes in the formation of complex organic nitrogen. We present here the yresults from a study designed to investigate how the inherent chemistry of lignin, leaf ylitter, and progressively advanced brown-rot wood decay impact the chemical reaction yof amino acids with this organic matter. Additionally, experiments in the presence of ybirnessite (MnO2) were also conducted to investigate the role of mineral induced phenol yoxidation on specific amino acid chemical humifcation processes. Solid and liquid state yNMR, 13C-labelled tetramethyl ammonium hydroxide thermochemolysis and stable ycarbon and nitrogen isotope ratio mass spectrometry were used to track the alteration yof litter material and document uptake of 13C and 15N labeled amino acids. yPreliminary results from birnessite-containing experiments suggest that the metal-ypromoted oxidation of the lignin, leaf litter, and, in particular, demethylated brown rot ywood residues, is necessary to convert the phenols to quinones of some type permitting yamine addition. This relationship is particularly true for the production of soluble yfractions after two and six weeks of reaction in the presence of the manganese oxides. yAdditionally, the production of leachable organic matter with incorporated N was ypromoted in the soluble fractions. Ongoing NMR studies will elucidate the nature of ythe chemical binding in these experiments. y

Interactions of tissue and fertilizer nitrogen on decomposition dynamics of lignin-rich conifer litter

USGS Publications Warehouse

Perakis, Steven S.; Matkins, Joselin J.; Hibbs, David E.

2012-01-01

High tissue nitrogen (N) accelerates decomposition of high-quality leaf litter in the early phases of mass loss, but the influence of initial tissue N variation on the decomposition of lignin-rich litter is less resolved. Because environmental changes such as atmospheric N deposition and elevated CO2 can alter tissue N levels within species more rapidly than they alter the species composition of ecosystems, it is important to consider how within-species variation in tissue N may shape litter decomposition and associated N dynamics. Douglas-fir (Pseudotsuga menziesii ) is a widespread lignin-rich conifer that dominates forests of high carbon (C) storage across western North America, and displays wide variation in tissue and litter N that reflects landscape variation in soil N. We collected eight unique Douglas-fir litter sources that spanned a two-fold range in initial N concentrations (0.67–1.31%) with a narrow range of lignin (29–35%), and examined relationships between initial litter chemistry, decomposition, and N dynamics in both ambient and N fertilized plots at four sites over 3 yr. High initial litter N slowed decomposition rates in both early (0.67 yr) and late (3 yr) stages in unfertilized plots. Applications of N fertilizer to litters accelerated early-stage decomposition, but slowed late-stage decomposition, and most strongly affected low-N litters, which equalized decomposition rates across litters regardless of initial N concentrations. Decomposition of N-fertilized litters correlated positively with initial litter manganese (Mn) concentrations, with litter Mn variation reflecting faster turnover of canopy foliage in high N sites, producing younger litterfall with high N and low Mn. Although both internal and external N inhibited decomposition at 3 yr, most litters exhibited net N immobilization, with strongest immobilization in low-N litter and in N-fertilized plots. Our observation for lignin-rich litter that high initial N can slow decomposition yet accelerate N release differs from findings where litter quality variation across species promotes coupled C and N release during decomposition. We suggest reevaluation of ecosystem models and projected global change effects to account for a potential decoupling of ecosystem C and N feedbacks through litter decomposition in lignin-rich conifer forests.

The Effect of Land-use Change and Management on Free-living N2 fixation in the Brazilian Atlantic Forest

NASA Astrophysics Data System (ADS)

De Oliveira Bomfim, B.; Silva, L. C. R.; Horwath, W. R.; Hello, J.; Doane, T. A.

2016-12-01

Globally, primary tropical forests are increasingly disturbed by deforestation, urbanization, agriculture, and cattle ranching. It has been recognized that the resulting (secondary) forests now play a key role in global biogeochemical cycles; however, little is known about alterations in forest function caused by the combination of disturbance and land use change. Fire, deforestation, and forest-to-monocrop conversion are all likely to affect biotic N inputs, yet our understanding of how free-living N2 fixation influences ecosystem response after disturbance remains poorly understood. Our research is assessing the role of asymbiotic (free-living) biological nitrogen fixation (BNF), a microbially-mediated process responsible for providing N inputs across terrestrial ecosystems and modulating the effect of fire and land cover in secondary forest succession. Free-living BNF is being quantified through incubations using stable isotope (15N2 labeling experiment) in different substrates (soil and leaf litter) under contrasting land use and management in the Brazilian Atlantic Forest, the most deforested Biome in Brazil with only 7% of its original cover. Soil and litter samples were collected in primary forests, 12-year secondary forests, Eucalyptus spp. plantations and 10-year Brachiaria brizantha pastures. Preliminary results indicate that free-living BNF rates did not vary significantly between either secondary land use (0.02 to 0.46 µg N2 fixed gDW-1 h-1), but rates were significantly higher in the litter layer (0.32 to 3.8 µg N2 fixed gDW-1 h-1) than in the surface soil (0 - 10 cm and 10 - 30 cm). Free-living BNF in this stretch of the Brazilian Atlantic Forest seems not to be significantly affected by contrasting land use and management.

Molecular evidence for lignin degradation in sulfate-reducing mangrove sediments (Amazônia, Brazil)

NASA Astrophysics Data System (ADS)

Dittmar, Thorsten; Lara, Rubén José

2001-05-01

- Molecular lignin analyses have become a powerful quantitative approach for estimating flux and fate of vascular plant organic matter in coastal and marine environments. The use of a specific molecular biomarker requires detailed knowledge of its decomposition rates relative to the associated organic matter and its structural diagenetic changes. To gain insight into the poorly known processes of anaerobic lignin diagenesis, molecular analyses were performed in the sulfate-reducing sediment of a north Brazilian mangrove. Organic matter in samples representing different diagenetic stages (i.e., fresh litter, a sediment core, and percolating water) was characterized by alkaline CuO oxidation for lignin composition, element (C, N), and stable carbon isotope analyses. On the basis of these results and on a balance model, long-term in situ decomposition rates of lignin in sulfate-reducing sediments were estimated for the first time. The half-life ( T1/2) of lignin derived from mangrove leaf litter (mainly Rhizophora mangle) was ˜150 yr in the upper 1.5 m of the sediment. Associated organic carbon from leaf tissue was depleted to ˜75% within weeks, followed by a slow mineralization in the sediment ( T1/2 ≈ 300 yr). Unlike the known pathways of lignin diagenesis, even highly degraded lignin did not show any alterations of the propyl or methoxyl side chains, as evident from stable acid to aldehyde ratios and the proportion of methoxylated phenols (vanillyl and syringyl phenols). Aromatic ring cleavage is probably the principal mechanism for lignin decay in the studied environment. Cinnamyl phenols were highly abundant in mangrove leaves and were rapidly depleted during early diagenesis. Thus, the cinnamyl to vanillyl ratio could be used as a tracer for early diagenesis even under the sulfate-reducing conditions. Syringyl phenols were removed from dissolved organic matter in interstitial water, probably by sorption onto the sediment. Suspended organic matter in a mangrove creek showed a different lignin signature than its source, namely sedimentary organic matter or mangrove litter, with clear evidence for propyl side chain oxidation. This was probably attributable to erosion of aerated thin sediment surface layers during mangrove inundation. Although particulate and dissolved organic matter in the mangrove creek have a common source, their compositional patterns were different, because of different pathways of release, degradation, and transport to the creek.

Artificial neural networks for modeling time series of beach litter in the southern North Sea.

PubMed

Schulz, Marcus; Matthies, Michael

2014-07-01

In European marine waters, existing monitoring programs of beach litter need to be improved concerning litter items used as indicators of pollution levels, efficiency, and effectiveness. In order to ease and focus future monitoring of beach litter on few important litter items, feed-forward neural networks consisting of three layers were developed to relate single litter items to general categories of marine litter. The neural networks developed were applied to seven beaches in the southern North Sea and modeled time series of five general categories of marine litter, such as litter from fishing, shipping, and tourism. Results of regression analyses show that general categories were predicted significantly moderately to well. Measured and modeled data were in the same order of magnitude, and minima and maxima overlapped well. Neural networks were found to be eligible tools to deliver reliable predictions of marine litter with low computational effort and little input of information. Copyright © 2014 Elsevier Ltd. All rights reserved.

A Greener Arctic: Vascular Plant Litter Input in Subarctic Peat Bogs Changes Soil Invertebrate Diets and Decomposition Patterns

NASA Astrophysics Data System (ADS)

Krab, E. J.; Berg, M. P.; Aerts, R.; van Logtestijn, R. S. P.; Cornelissen, H. H. C.

2014-12-01

Climate-change-induced trends towards shrub dominance in subarctic, moss-dominated peatlands will most likely have large effects on soil carbon (C) dynamics through an input of more easily decomposable litter. The mechanisms by which this increase in vascular litter input interacts with the abundance and diet-choice of the decomposer community to alter C-processing have, however, not yet been unraveled. We used a novel 13C tracer approach to link invertebrate species composition (Collembola), abundance and species-specific feeding behavior to C-processing of vascular and peat moss litters. We incubated different litter mixtures, 100% Sphagnum moss litter, 100% Betula leaf litter, and a 50/50 mixture of both, in mesocosms for 406 days. We revealed the transfer of C from the litters to the soil invertebrate species by 13C labeling of each of the litter types and assessed 13C signatures of the invertebrates Collembola species composition differed significantly between Sphagnum and Betula litter. Within the 'single type litter' mesocosms, Collembola species showed different 13C signatures, implying species-specific differences in diet choice. Surprisingly, the species composition and Collembola abundance changed relatively little as a consequence of Betula input to a Sphagnum based system. Their diet choice, however, changed drastically; species-specific differences in diet choice disappeared and approximately 67% of the food ingested by all Collembola originated from Betula litter. Furthermore, litter decomposition patterns corresponded to these findings; mass loss of Betula increased from 16.1% to 26.2% when decomposing in combination with Sphagnum, while Sphagnum decomposed even slower in combination with Betula litter (1.9%) than alone (4.7%). This study is the first to empirically show that collective diet shifts of the peatland decomposer community from mosses towards vascular plant litter may drive altered decomposition patterns. In addition, we showed that although species-specific differences in Collembola feeding behavior appear to exist, species are very plastic in their diet. This implies that changes in C turnover rates with vegetation shifts, might well be due to diet shifts of the present decomposer community rather than by changes in species composition.

Dynamics of the Leaf-Litter Arthropod Fauna Following Fire in a Neotropical Woodland Savanna

PubMed Central

Vasconcelos, Heraldo L.; Pacheco, Renata; Silva, Raphael C.; Vasconcelos, Pedro B.; Lopes, Cauê T.; Costa, Alan N.; Bruna, Emilio M.

2009-01-01

Fire is an important agent of disturbance in tropical savannas, but relatively few studies have analyzed how soil-and-litter dwelling arthropods respond to fire disturbance despite the critical role these organisms play in nutrient cycling and other biogeochemical processes. Following the incursion of a fire into a woodland savanna ecological reserve in Central Brazil, we monitored the dynamics of litter-arthropod populations for nearly two years in one burned and one unburned area of the reserve. We also performed a reciprocal transplant experiment to determine the effects of fire and litter type on the dynamics of litter colonization by arthropods. Overall arthropod abundance, the abundance of individual taxa, the richness of taxonomic groups, and the species richness of individual taxa (Formiciade) were lower in the burned site. However, both the ordinal-level composition of the litter arthropod fauna and the species-level composition of the litter ant fauna were not dramatically different in the burned and unburned sites. There is evidence that seasonality of rainfall interacts with fire, as differences in arthropod abundance and diversity were more pronounced in the dry than in the wet season. For many taxa the differences in abundance between burned and unburned sites were maintained even when controlling for litter availability and quality. In contrast, differences in abundance for Collembola, Formicidae, and Thysanoptera were only detected in the unmanipulated samples, which had a lower amount of litter in the burned than in the unburned site throughout most of our study period. Together these results suggest that arthropod density declines in fire-disturbed areas as a result of direct mortality, diminished resources (i.e., reduced litter cover) and less favorable microclimate (i.e., increased litter desiccation due to reduction in tree cover). Although these effects were transitory, there is evidence that the increasingly prevalent fire return interval of only 1–2 years may jeopardize the long-term conservation of litter arthropod communities. PMID:19898619

Arbuscular mycorrhiza enhance the rate of litter decomposition while inhibiting soil microbial community development

PubMed Central

Gui, Heng; Hyde, Kevin; Xu, Jianchu; Mortimer, Peter

2017-01-01

Although there is a growing amount of evidence that arbuscular mycorrhizal fungi (AMF) influence the decomposition process, the extent of their involvement remains unclear. Therefore, given this knowledge gap, our aim was to test how AMF influence the soil decomposer communities. Dual compartment microcosms, where AMF (Glomus mosseae) were either allowed access (AM+) to or excluded (AM−) from forest soil compartments containing litterbags (leaf litter from Calophyllum polyanthum) were used. The experiment ran for six months, with destructive harvests at 0, 90, 120, 150, and 180 days. For each harvest we measured AMF colonization, soil nutrients, litter mass loss, and microbial biomass (using phospholipid fatty acid analysis (PLFA)). AMF significantly enhanced litter decomposition in the first 5 months, whilst delaying the development of total microbial biomass (represented by total PLFA) from T150 to T180. A significant decline in soil available N was observed through the course of the experiment for both treatments. This study shows that AMF have the capacity to interact with soil microbial communities and inhibit the development of fungal and bacterial groups in the soil at the later stage of the litter decomposition (180 days), whilst enhancing the rates of decomposition. PMID:28176855

Microdiversity of an Abundant Terrestrial Bacterium Encompasses Extensive Variation in Ecologically Relevant Traits

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chase, Alexander B.; Karaoz, Ulas; Brodie, Eoin L.

ABSTRACT Much genetic diversity within a bacterial community is likely obscured by microdiversity within operational taxonomic units (OTUs) defined by 16S rRNA gene sequences. However, it is unclear how variation within this microdiversity influences ecologically relevant traits. Here, we employ a multifaceted approach to investigate microdiversity within the dominant leaf litter bacterium, Curtobacterium , which comprises 7.8% of the bacterial community at a grassland site undergoing global change manipulations. We use cultured bacterial isolates to interpret metagenomic data, collected in situ over 2 years, together with lab-based physiological assays to determine the extent of trait variation within this abundant OTU. Themore » response of Curtobacterium to seasonal variability and the global change manipulations, specifically an increase in relative abundance under decreased water availability, appeared to be conserved across six Curtobacterium lineages identified at this site. Genomic and physiological analyses in the lab revealed that degradation of abundant polymeric carbohydrates within leaf litter, cellulose and xylan, is nearly universal across the genus, which may contribute to its high abundance in grassland leaf litter. However, the degree of carbohydrate utilization and temperature preference for this degradation varied greatly among clades. Overall, we find that traits within Curtobacterium are conserved at different phylogenetic depths. We speculate that similar to bacteria in marine systems, diverse microbes within this taxon may be structured in distinct ecotypes that are key to understanding Curtobacterium abundance and distribution in the environment. IMPORTANCE Despite the plummeting costs of sequencing, characterizing the fine-scale genetic diversity of a microbial community—and interpreting its functional importance—remains a challenge. Indeed, most studies, particularly studies of soil, assess community composition at a broad genetic level by classifying diversity into taxa (OTUs) defined by 16S rRNA sequence similarity. However, these classifications potentially obscure variation in traits that result in fine-scale ecological differentiation among closely related strains. Here, we investigated “microdiversity” in a highly diverse and poorly characterized soil system (leaf litter in a southern Californian grassland). We focused on the most abundant bacterium, Curtobacterium , which by standard methods is grouped into only one OTU. We find that the degree of carbohydrate usage and temperature preference vary within the OTU, whereas its responses to changes in precipitation are relatively uniform. These results suggest that microdiversity may be key to understanding how soil bacterial diversity is linked to ecosystem functioning.« less

Microdiversity of an Abundant Terrestrial Bacterium Encompasses Extensive Variation in Ecologically Relevant Traits

DOE PAGES

Chase, Alexander B.; Karaoz, Ulas; Brodie, Eoin L.; ...

2017-11-14

ABSTRACT Much genetic diversity within a bacterial community is likely obscured by microdiversity within operational taxonomic units (OTUs) defined by 16S rRNA gene sequences. However, it is unclear how variation within this microdiversity influences ecologically relevant traits. Here, we employ a multifaceted approach to investigate microdiversity within the dominant leaf litter bacterium, Curtobacterium , which comprises 7.8% of the bacterial community at a grassland site undergoing global change manipulations. We use cultured bacterial isolates to interpret metagenomic data, collected in situ over 2 years, together with lab-based physiological assays to determine the extent of trait variation within this abundant OTU. Themore » response of Curtobacterium to seasonal variability and the global change manipulations, specifically an increase in relative abundance under decreased water availability, appeared to be conserved across six Curtobacterium lineages identified at this site. Genomic and physiological analyses in the lab revealed that degradation of abundant polymeric carbohydrates within leaf litter, cellulose and xylan, is nearly universal across the genus, which may contribute to its high abundance in grassland leaf litter. However, the degree of carbohydrate utilization and temperature preference for this degradation varied greatly among clades. Overall, we find that traits within Curtobacterium are conserved at different phylogenetic depths. We speculate that similar to bacteria in marine systems, diverse microbes within this taxon may be structured in distinct ecotypes that are key to understanding Curtobacterium abundance and distribution in the environment. IMPORTANCE Despite the plummeting costs of sequencing, characterizing the fine-scale genetic diversity of a microbial community—and interpreting its functional importance—remains a challenge. Indeed, most studies, particularly studies of soil, assess community composition at a broad genetic level by classifying diversity into taxa (OTUs) defined by 16S rRNA sequence similarity. However, these classifications potentially obscure variation in traits that result in fine-scale ecological differentiation among closely related strains. Here, we investigated “microdiversity” in a highly diverse and poorly characterized soil system (leaf litter in a southern Californian grassland). We focused on the most abundant bacterium, Curtobacterium , which by standard methods is grouped into only one OTU. We find that the degree of carbohydrate usage and temperature preference vary within the OTU, whereas its responses to changes in precipitation are relatively uniform. These results suggest that microdiversity may be key to understanding how soil bacterial diversity is linked to ecosystem functioning.« less

Leaf removal by sesarmid crabs in Bangrong mangrove forest, Phuket, Thailand; with emphasis on the feeding ecology of Neoepisesarma versicolor

NASA Astrophysics Data System (ADS)

Thongtham, Nalinee; Kristensen, Erik; Puangprasan, Som-Ying

2008-12-01

Field measurements on leaf removal by populations of sesarmid crabs at different locations in the Bangrong mangrove forest, Phuket, Thailand, indicated that crabs on average can remove 87% of the daily leaf litter fall by ingestion or burial. The removal rate is correlated positively with the number of crab burrows and negatively with tidal inundation time. The results from the field were supplemented with observations on the behavior of Neoepisesarma versicolor in laboratory microcosms and a mangrove mesocosm. N. versicolor feeds primarily at night and total time spent feeding was up to an order of magnitude higher in the artificial microcosms than under simulated in situ conditions in the mesocosm. Most of the time during both day and night was spent resting near the entrance or inside burrows. N. versicolor mainly feeds on mangrove leaves and scraps of food material from the sediment surface. This is supported by examinations of stomach content, which showed that 62% is composed of higher plant material and 38% of detritus and mineral particles from the sediment. The nutritive value of leaves and detritus is insufficient to maintain crab growth. Sesarmid crabs may instead obtain the needed nutrients by occasional consumption of nitrogen-rich animal tissues, such as carcasses of fish and crustaceans, as indicated by the presence of animal remains in the stomach and the willingness of crabs to consume fish meat. Laboratory experiments on leaf consumption and leaf preferences of N. versicolor indicate that they preferentially feed on brown leaves, if available, followed by green and yellow leaves. If all species of sesarmid crabs in the Bangrong mangrove forest consume leaves at the same rate as N. versicolor, they could potentially ingest 52% of the total litter fall.

Banana leaf and glucose mineralization and soil organic matter in microhabitats of banana plantations under long-term pesticide use.

PubMed

Blume, Elena; Reichert, José Miguel

2015-06-01

Soil organic matter (SOM) and microbial activity are key components of soil quality and sustainability. In the humid tropics of Costa Rica 3 pesticide regimes were studied-fungicide (low input); fungicide and herbicide (medium input); and fungicide, herbicide, and nematicide (high input)-under continuous banana cultivation for 5 yr (young) or 20 yr (old) in 3 microhabitats-nematicide ring around plants, litter pile of harvested banana, and bare area between litter pile and nematicide ring. Soil samples were incubated sequentially in the laboratory: unamended, amended with glucose, and amended with ground banana leaves. Soil organic matter varied with microhabitat, being greatest in the litter pile, where microbes had the greatest basal respiration with ground banana leaf, whereas microbes in the nematicide ring had the greatest respiration with glucose. These results suggest that soil microbes adapt to specific microhabitats. Young banana plantations had similar SOM compared with old plantations, but the former had greater basal microbial respiration in unamended and in glucose-amended soil and greater first-order mineralization rates in glucose-amended soil, thus indicating soil biological quality decline over time. High pesticide input did not decrease microbial activity or mineralization rate in surface soil. In conclusion, microbial activity in tropical volcanic soil is highly adaptable to organic and inorganic inputs. © 2015 SETAC.

The invasive species Alliaria petiolata (garlic mustard) increases soil nutrient availability in northern hardwood-conifer forests.

PubMed

Rodgers, Vikki L; Wolfe, Benjamin E; Werden, Leland K; Finzi, Adrien C

2008-09-01

The invasion of non-native plants can alter the diversity and activity of soil microorganisms and nutrient cycling within forests. We used field studies to analyze the impact of a successful invasive groundcover, Alliaria petiolata, on fungal diversity, soil nutrient availability, and pH in five northeastern US forests. We also used laboratory and greenhouse experiments to test three mechanisms by which A. petiolata may alter soil processes: (1) the release of volatile, cyanogenic glucosides from plant tissue; (2) the exudation of plant secondary compounds from roots; and (3) the decomposition of litter. Fungal community composition was significantly different between invaded and uninvaded soils at one site. Compared to uninvaded plots, plots invaded by A. petiolata were consistently and significantly higher in N, P, Ca and Mg availability, and soil pH. In the laboratory, the release of volatile compounds from the leaves of A. petiolata did not significantly alter soil N availability. Similarly, in the greenhouse, the colonization of native soils by A. petiolata roots did not alter soil nutrient cycling, implying that the exudation of secondary compounds has little effect on soil processes. In a leaf litter decomposition experiment, however, green rosette leaves of A. petiolata significantly increased the rate of decomposition of native tree species. The accelerated decomposition of leaf litter from native trees in the presence of A. petiolata rosette leaves shows that the death of these high-nutrient-content leaves stimulates decomposition to a greater extent than any negative effect that secondary compounds may have on the activity of the microbes decomposing the native litter. The results presented here, integrated with recent related studies, suggest that this invasive plant may change soil nutrient availability in such a way as to create a positive feedback between site occupancy and continued proliferation.

Seasonal variations in methane fluxes in response to summer warming and leaf litter addition in a subarctic heath ecosystem

NASA Astrophysics Data System (ADS)

Pedersen, Emily Pickering; Elberling, Bo; Michelsen, Anders

2017-08-01

Methane (CH4) is a powerful greenhouse gas controlled by both biotic and abiotic processes. Few studies have investigated CH4 fluxes in subarctic heath ecosystems, and climate change-induced shifts in CH4 flux and the overall carbon budget are therefore largely unknown. Hence, there is an urgent need for long-term in situ experiments allowing for the study of ecosystem processes over time scales relevant to environmental change. Here we present in situ CH4 and CO2 flux measurements from a wet heath ecosystem in northern Sweden subjected to 16 years of manipulations, including summer warming with open-top chambers, birch leaf litter addition, and the combination thereof. Throughout the snow-free season, the ecosystem was a net sink of CH4 and CO2 (CH4 -0.27 mg C m-2 d-1; net ecosystem exchange -1827 mg C m-2 d-1), with highest CH4 uptake rates (-0.70 mg C m-2 d-1) during fall. Warming enhanced net CO2 flux, while net CH4 flux was governed by soil moisture. Litter addition and the combination with warming significantly increased CH4 uptake rates, explained by a pronounced soil drying effect of up to 32% relative to ambient conditions. Both warming and litter addition also increased the seasonal average concentration of dissolved organic carbon in the soil. The site was a carbon sink with a net uptake of 60 g C m-2 over the snow-free season. However, warming reduced net carbon uptake by 77%, suggesting that this ecosystem type might shift from snow-free season sink to source with increasing summer temperatures.

Biochars impact on water infiltration and water quality through a compacted subsoil layer.

PubMed

Novak, Jeff; Sigua, Gilbert; Watts, Don; Cantrell, Keri; Shumaker, Paul; Szogi, Ariel; Johnson, Mark G; Spokas, Kurt

2016-01-01

Soils in the SE USA Coastal Plain region frequently have a compacted subsoil layer (E horizon), which is a barrier for water infiltration. Four different biochars were evaluated to increase water infiltration through a compacted horizon from a Norfolk soil (fine-loamy, kaolinitic, thermic, Typic Kandiudult). In addition, we also evaluated biochars effect on water quality. Biochars were produced by pyrolysis at 500 °C from pine chips (Pinus taeda), poultry litter (Gallus domesticus) feedstocks, and as blends (50:50 and 80:20) of pine chip:poultry litter. Prior to pyrolysis, the feedstocks were pelletized and sieved to >2-mm pellets. Each biochar was mixed with the subsoil at 20 g/kg (w/w) and the mixture was placed in columns. The columns were leached four times with Milli-Q water over 128 d of incubation. Except for the biochar produced from poultry litter, all other applied biochars resulted in significant water infiltration increases (0.157-0.219 mL min(-1); p<0.05) compared to the control (0.095 mL min(-1)). However, water infiltration in each treatment were influenced by additional water leaching. Leachates were enriched in PO4, SO4, Cl, Na, and K after addition of poultry litter biochar, however, their concentrations declined in pine chip blended biochar treatments and after multiple leaching. Adding biochars (except 100% poultry litter biochar) to a compacted subsoil layer can initially improve water infiltration, but, additional leaching revealed that the effect remained only for the 50:50 pine chip:poultry litter blended biochar while it declined in other biochar treatments. Published by Elsevier Ltd.

Crayfish Impact Desert River Ecosystem Function and Litter-Dwelling Invertebrate Communities through Association with Novel Detrital Resources

PubMed Central

Moody, Eric K.; Sabo, John L.

2013-01-01

Shifts in plant species distributions due to global change are increasing the availability of novel resources in a variety of ecosystems worldwide. In semiarid riparian areas, hydric pioneer tree species are being replaced by drought-tolerant plant species as water availability decreases. Additionally, introduced omnivorous crayfish, which feed upon primary producers, allochthonous detritus, and benthic invertebrates, can impact communities at multiple levels through both direct and indirect effects mediated by drought-tolerant plants. We tested the impact of both virile crayfish (Orconectes virilis) and litter type on benthic invertebrates and the effect of crayfish on detrital resources across a gradient of riparian vegetation drought-tolerance using field cages with leaf litter bags in the San Pedro River in Southeastern Arizona. Virile crayfish increased breakdown rate of novel drought-tolerant saltcedar (Tamarix ramosissima), but did not impact breakdown of drought-tolerant seepwillow (Baccharis salicifolia) or hydric Fremont cottonwood (Populus fremontii) and Gooding's willow (Salix goodingii). Effects on invertebrate diversity were observed at the litter bag scale, but no effects were found at the cage scale. Crayfish decreased alpha diversity of colonizing macroinvertebrates, but did not affect beta diversity. In contrast, the drought-tolerant litter treatment decreased beta diversity relative to hydric litter. As drought-tolerant species become more abundant in riparian zones, their litter will become a larger component of the organic matter budget of desert streams which may serve to homogenize the litter-dwelling community and support elevated populations of virile crayfish. Through impacts at multiple trophic levels, crayfish have a significant effect on desert stream ecosystems. PMID:23667600

Effects of the interception of litterfall by the understory on carbon cycling in eucalyptus plantations of South China.

PubMed

Yang, Long; Wang, Jun; Huang, Yuhui; Hui, Dafeng; Wen, Meili

2014-01-01

For the purposes of forest restoration, carbon (C) fixation, and economic improvement, eucalyptus (Eucalyptus urophylla) has been widely planted in South China. The understory of eucalyptus plantations is often occupied by a dense community of the fern Dicranopteris dichotoma, which intercepts tree canopy leaf litter before it reaches the ground. To understand the effects of this interception of litterfall on C cycling in eucalyptus plantations, we quantified the mass of intercepted litter and the influences of litterfall interception on litter decomposition and soil respiration. The total mass of E. urophylla litterfall collected on the understory was similar to that collected by the traditional litter trap method. All of the eucalyptus litterfall is intercepted by the D. dichotoma canopy. Of the litterfall that was intercepted by D. dichotoma, 20-40% and 60-80% was intercepted by the top (50-100 cm) and bottom (0-50 cm) of the understory canopy, respectively. Intercepted litterfall decomposed faster at the bottom of understory canopy (at the base of the plants) than at the top, and decomposition was slower on the soil surface in the absence of understory than on any location in the understory canopy. Soil respiration was highest when both the understory and litter were present and was lowest when both the understory and litter were absent. These results indicate that litterfall interception changed carbon flow between aboveground and belowground through litter decomposition and soil respiration, which changed carbon cycling in eucalyptus plantations. The effects of the understory on litter decomposition and soil respiration should be considered in ecosystem carbon models.

Prescribed fire experiences on crop residue removal for biomass exploitations. Application to the maritime pine forests in the Mediterranean Basin.

PubMed

Molina, Juan Ramón; García, Juan Pedro; Fernández, Juan José; Rodríguez Y Silva, Francisco

2018-01-15

Socioeconomic changes, climate change, rural migration and fire exclusion have led to a high woody biomass accumulation increasing potential wildfire severity. Mechanical thinning and prescribed burning practices are commonly used to prevent large fires. The purpose of this study was to assess burning treatment effectiveness following mechanical thinning from biomass harvesting. Prescribed burning to reduce residue removal could help mitigate fire behavior, mainly in strategic management or critical focal points. Field samplings were conducted before and immediately after burnings on different environmental scenarios where fuel load was classified by categories. Prescribed fires reduced available fuel in all fuel categories, mainly in surface litter layer. Total fuel load reduction ranged from 59.07% to 86.18%. In this sense, fuel reduction effects were more pronounced when burns were conducted fewer than 10% on surface litter moisture. The difference in fuel consumption among scenarios was higher for most all woody fuel components and decomposition litter layer than for surface litter layer. Managers can use this information to design technical prescription to achieve the targets while decomposed litter retention maintaining the soil properties and biodiversity. Understanding the most effective "burn window" should help better plan prescribed burning, both in term of fire behavior and fuel consumption, without altering ecosystem properties. Copyright © 2017 Elsevier B.V. All rights reserved.

[Dynamics of soil physical properties and biological soil crust during the vegetation restoration process of abandoned croplands in the Ordos Plateau, China].

PubMed

Cai, Wen Tao; Li, He Yi; Lai, Li Ming; Zhang, Xiao Long; Guan, Tian Yu; Zhou, Ji Hua; Jiang, Lian He; Zheng, Yuan Run

2017-03-18

A series of typical abandoned croplands in the regions of Ruanliang and Yingliang in the Ordos Plateau, China, were selected, and dynamics of the surface litter, biological soil crust and soil bulk density, soil texture, and soil moisture in different soil layers were investigated. The results showed that in the abandoned cropland in Ruanliang, the clay particle content and surface litter of the surface soil layer (0-10 cm) increased during the restoration process, while that of soil bulk density substantially decreased and soil water content slightly increased in the surface soil. In the medium soil layer (10-30 cm), the clay particle content increased and the soil water content slightly decreased. In the deep soil layer (30-50 cm), there was a relatively large variation in the physical properties. In the abandoned cropland in Yingliang, the coverage of litter and the coverage and thickness of the biological soil crust increased during the abandonment process. The surface soil bulk density, soil clay particle content and soil water content remained constant in 0-10 cm soil layer, while the physical properties varied substantially in 10-40 cm soil layer. The shallow distribution of the soil water content caused by the accumulation of the litter and clay particles on the soil surface might be the key reason of the replacement of the semi-shrub Artemisia ordosica community with a perennial grass community over the last 20 years of the abandoned cropland in Ruanliang. The relatively high soil water content in the shallow layer and the development of the biological soil crust might explain why the abandoned cropland in Yingliang was not invaded by the semi-shrub A. ordosica during the restoration process.

Solar radiation uncorks the lignin bottleneck on plant litter decomposition in terrestrial ecosystems

NASA Astrophysics Data System (ADS)

Austin, A.; Ballare, C. L.; Méndez, M. S.

2015-12-01

Plant litter decomposition is an essential process in the first stages of carbon and nutrient turnover in terrestrial ecosystems, and together with soil microbial biomass, provide the principal inputs of carbon for the formation of soil organic matter. Photodegradation, the photochemical mineralization of organic matter, has been recently identified as a mechanism for previously unexplained high rates of litter mass loss in low rainfall ecosystems; however, the generality of this process as a control on carbon cycling in terrestrial ecosystems is not known, and the indirect effects of photodegradation on biotic stimulation of carbon turnover have been debated in recent studies. We demonstrate that in a wide range of plant species, previous exposure to solar radiation, and visible light in particular, enhanced subsequent biotic degradation of leaf litter. Moreover, we demonstrate that the mechanism for this enhancement involves increased accessibility for microbial enzymes to plant litter carbohydrates due to a reduction in lignin content. Photodegradation of plant litter reduces the structural and chemical bottleneck imposed by lignin in secondary cell walls. In litter from woody plant species, specific interactions with ultraviolet radiation obscured facilitative effects of solar radiation on biotic decomposition. The generalized positive effect of solar radiation exposure on subsequent microbial activity is mediated by increased accessibility to cell wall polysaccharides, which suggests that photodegradation is quantitatively important in determining rates of mass loss, nutrient release and the carbon balance in a broad range of terrestrial ecosystems.

Effect of different types of litter material for rearing broilers.

PubMed

Swain, B K; Sundaram, R N

2000-07-01

1. Coir dust was evaluated as broiler litter in comparison with sawdust and rice husk using 135 commercial broilers. Forty-five broiler chicks were reared to 42 d on a 50 mm layer of each of these litters. 2. Birds reared on coir dust showed no difference in food consumption, body weight gain, food conversion efficiency production number and survivability in comparison to those reared on saw dust and rice husk. 3. It was concluded that coir dust is suitable as broiler litter when cheaply available.

Low dissolved organic carbon input from fresh litter to deep mineral soils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Froeberg, Mats J; Jardine, Philip M; Hanson, Paul J

2007-01-01

Dissolved organic carbon (DOC) leached from recent litter in the forest floor has been suggested to be an important source of C to the mineral soil of forest ecosystems. In order to determine the rate at which this flux of C occurs we have taken advantage of a local release of 14C at Oak Ridge National Laboratory Reservation, USA (latitude N 35 58'; longitude W 84 16'). Eight replicate 7x7 m plots were estab lished at four field sites on the reservation in an upland oak forest setting. Half of the plots were provided with 14C-enriched litter (∆14C ≈1000 ),more » and the other half with near-background litter (∆14C ≈220 ) over multiple years. Differences in the labeled leaf litter were used to quantify the movement of litter derived DOC through the soil profile. Soil solutions were collected over several years with tension lysimeters at 15 and 70 cm depth and measured for DOC concentration and 14C abundance. The net amount of DOC retained between 15 and 70 cm was 1.5-6 g m-2 y-1. There were significant effects of the litter additions on the 14C abundance in the DOC, but the net transport of 14C from the added litter was small. The difference in ∆14C between the treatments with enriched and near-background litter was only about 130 at both depths, which is small compared with the difference in Δ14C in the added litter. The primary source of DOC within the mineral soil must therefore have been either the Oe/Oa horizon or the organic matter in the mineral soil. Over a 2-year time frame, leaching of DOC from recent litter did not have a major impact on the C stock in the mineral soil below 15 cm in this ecosystem.« less

Genetic Based Plant Resistance and Susceptibility Traits to Herbivory Influence Needle and Root Litter Nutrient Dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Classen, Aimee T; Chapman, Samantha K.; Whitham, Thomas G

2007-01-01

It is generally assumed that leaf and root litter decomposition have similar drivers and that nutrient release from these substrates is synchronized. Few studies have examined these assumptions, and none has examined how plant genetics (i.e., plant susceptibility to herbivory) could affect these relationships. Here we examine the effects of herbivore susceptibility and resistance on needle and fine root litter decomposition of pi on pine, Pinus edulis. The study population consists of individual trees that are either susceptible or resistant to herbivory by the pi on needle scale, Matsucoccus acalyptus, or the stem-boring moth, Dioryctria albovittella. Genetic analyses and experimentalmore » removals and additions of these insects have identified trees that are naturally resistant and susceptible to these insects. These herbivores increase the chemical quality of litter inputs and alter soil microclimate, both of which are important decomposition drivers. Our research leads to four major conclusions: Herbivore susceptibility and resistance effects on 1) needle litter mass loss and phosphorus (P) retention in moth susceptible and resistant litter are governed by microclimate, 2) root litter nitrogen (N) and P retention, and needle litter N retention are governed by litter chemical quality, 3) net nutrient release from litter can reverse over time, 4) root and needle litter mass loss and nutrient release are determined by location (above- vs. belowground), suggesting that the regulators of needle and root decomposition differ at the local scale. Understanding of decomposition and nutrient retention in ecosystems requires consideration of herbivore effects on above- and belowground processes and how these effects may be governed by plant genotype. Because an underlying genetic component to herbivory is common to most ecosystems of the world and herbivory may increase in climatic change scenarios, it is important to evaluate the role of plant genetics in affecting carbon and nutrient fluxes.« less

Enhanced summer warming reduces fungal decomposer diversity and litter mass loss more strongly in dry than in wet tundra.

PubMed

Christiansen, Casper T; Haugwitz, Merian S; Priemé, Anders; Nielsen, Cecilie S; Elberling, Bo; Michelsen, Anders; Grogan, Paul; Blok, Daan

2017-01-01

Many Arctic regions are currently experiencing substantial summer and winter climate changes. Litter decomposition is a fundamental component of ecosystem carbon and nutrient cycles, with fungi being among the primary decomposers. To assess the impacts of seasonal climatic changes on litter fungal communities and their functioning, Betula glandulosa leaf litter was surface-incubated in two adjacent low Arctic sites with contrasting soil moisture regimes: dry shrub heath and wet sedge tundra at Disko Island, Greenland. At both sites, we investigated the impacts of factorial combinations of enhanced summer warming (using open-top chambers; OTCs) and deepened snow (using snow fences) on surface litter mass loss, chemistry and fungal decomposer communities after approximately 1 year. Enhanced summer warming significantly restricted litter mass loss by 32% in the dry and 17% in the wet site. Litter moisture content was significantly reduced by summer warming in the dry, but not in the wet site. Likewise, fungal total abundance and diversity were reduced by OTC warming at the dry site, while comparatively modest warming effects were observed in the wet site. These results suggest that increased evapotranspiration in the OTC plots lowered litter moisture content to the point where fungal decomposition activities became inhibited. In contrast, snow addition enhanced fungal abundance in both sites but did not significantly affect litter mass loss rates. Across sites, control plots only shared 15% of their fungal phylotypes, suggesting strong local controls on fungal decomposer community composition. Nevertheless, fungal community functioning (litter decomposition) was negatively affected by warming in both sites. We conclude that although buried soil organic matter decomposition is widely expected to increase with future summer warming, surface litter decay and nutrient turnover rates in both xeric and relatively moist tundra are likely to be significantly restricted by the evaporative drying associated with warmer air temperatures. © 2016 John Wiley & Sons Ltd.

HIGH FOLIAR NITROGEN IN DESERT SHRUBS: AN IMPORTANT ECOSYSTEM TRAIT OR DEFECTIVE DESERT DOCTRINE?

EPA Science Inventory

Nitrogen concentrations in green and senesced leaves of perennial desert shrubs were compiled from a worldwide literature search to test the validity of the doctrine that desert shrubs produce foliage and leaf litter much richer in nitrogen than that in the foliage of plants from...

An Assessment of Cellulose Filters as a Standardized Material for Measuring Litter Breakdown in Headwater Streams

EPA Science Inventory

The decay rate of cellulose filters and associated chemical and biological characteristics were compared to those of white oak (Quercus alba) leaves to determine if cellulose filters could be a suitable standardized material for measuring deciduous leaf breakdown in headwater str...

An assessment of cellulose filters as a standardized material for measuring litter breakdown in headwater streams

EPA Science Inventory

The decay rate of cellulose filters and associated chemical and biological characteristics were compared to those of white oak (Quercus alba) leaves to determine if cellulose filters could be a suitable standardized material for measuring deciduous leaf breakdown in headwater str...

Production of Chromophoric Dissolved Organic Matter from Mangrove Leaf Litter and Floating Sargassum Colonies

EPA Science Inventory

Chromophoric dissolved organic matter (CDOM) strongly absorbs solar radiation in the blue-green and serves as the primary attenuator of water column ultraviolet radiation (UV-R). CDOM interferes with remote sensing of ocean chlorophyll and can control UV-R-induced damage to light...

Redescription of two species of Oplitis Berlese (Acari, Mesostigmata, Oplitidae) from Iran

PubMed Central

Babaeian, Esmaeil; Saboori, Alireza; Gwiazdowicz, Dariusz J.; Etemad, Vahid

2016-01-01

Abstract Two new species records of Oplitidae, Oplitis exopodi Hunter & Farrier, 1975 and Oplitis sarcinulus Hunter & Farrier, 1976 are redescribed based on Iranian specimens from leaf-litter forest in Mazandaran province, northern Iran. A key to the Iranian species of Oplitis is presented. PMID:27587975

Decomposition of terrestrial resource subsidies in headwater streams: Does consumer diversity matter?

Treesearch

David Stoker; Amber J. Falkner; Kelly M. Murray; Ashley K. Lang; Thomas R. Barnum; Jeffrey Hepinstall-Cymerman; Michael J. Conroy; Robert J. Cooper; Catherine M. Pringle

2017-01-01

Resource subsidies and biodiversity are essential for maintaining community structure and ecosystem functioning, but the relative importance of consumer diversity and resource characteristics to decomposition remains unclear. Forested headwater streams are detritus-based systems, dependent on leaf litter inputs from adjacent riparian ecosystems, and...

Rhododendron thickets alter N Cycling and soul extracellular enzyme activities in southern Appalachian hardwood forests

Treesearch

Nina Wurzburger; Ronald L. Hendrick

2007-01-01

Rhododendron maximum L., a spreading understory shrub, inhibits overstory. Regeneration and alters forest community structure in southern Appalachian hardwood forests. Using paired plots and reciprocal litter transplants in forests with and without R. maximum cover, we examined the influence of R. maximum on Leaf...

PERSISTENCE IN SOIL OF TRANSGENIC PLANT PRODUCED BACILLUS THURINGIENSIS VAR. KURSTAKI O-ENDOTOXIN1

EPA Science Inventory

Transgenic plants that produce pesticidal proteins will release these proteins into the soil when these plants are incorporated into the soil by tillage or as leaf litter. Little is known about the fate and persistence of transgenic plant pesticidal products in the soil. We used ...

An Experimental Ecological Study of a Garden Compost Heap.

ERIC Educational Resources Information Center

Curds, Tracy

1985-01-01

A quantitative study of the fauna of a garden compost heap shows it to be similar to that of organisms found in soil and leaf litter. Materials, methods, and results are discussed and extensive tables of fauna lists, wet/dry masses, and statistical analyses are presented. (Author/DH)

An Experimental Study of the Effects of Litter and Duff Consumption and Ash Formation on Post-Fire Runoff.

NASA Astrophysics Data System (ADS)

Woods, S. W.; Balfour, V.

2007-12-01

Consumption of the litter and duff layers in forest wildfires can lead to substantial increases in the frequency and magnitude of overland flow. These increases result from the loss of storage in the organic surface layer, reduced surface roughness, and from sealing of the exposed mineral soil surface. The presence of an ash layer may accentuate surface sealing by providing an additional source of fine material, or it may reduce runoff by storing rainfall and by protecting the soil surface from raindrop impacts. We used simulated rainfall experiments to assess the effects of litter and duff consumption and the presence of ash layers of varying thickness on post fire runoff at two forested sites in western Montana, one with sandy loam soils formed out of granodiorite and the other with gravelly silt loam soils formed out of argillite. At each site we measured the runoff from simulated rainfall in replicated 0.5 m2 plots before and after application of the following treatments: 1) burning with a fuel load of 90 Mg ha-1, 2) manual removal of the litter and duff layers, 3) addition of 0.5, 2.5 and 5 cm of ash to plots from which the litter and duff had previously been removed, and 4) addition of the same depths of ash to burned plots at the sandy loam site. In the burned plots the surface litter and duff layers were completely consumed and a <1cm layer of black and gray ash and char was formed, indicating a moderate severity burn. The mean soil temperature in the upper 1 cm of the mineral soil was 70° C, and there was no detectable increase in water repellency. The mean final infiltration capacity of the burned sandy loam plots was 35 mm hr-1 compared to a pre-fire mean of 87 mm hr-1, while in the gravelly silt loam plots the pre- and post burn infiltration capacities (27 and 31 mm hr- 1) were not significantly different. Manual removal of the litter and duff layers reduced the mean final infiltration capacity in the sandy loam plots from 64 mm hr-1 to 40 mm hr-1 and in the gravelly silt loam plots from 23 mm hr-1 to 16 mm hr-1. We attribute decreases in infiltration due to the burning and duff removal treatments primarily to surface sealing. In the sandy loam plots, burning may have had a greater effect on infiltration than duff removal because the thin ash layer in the burned plots provided an additional source of fine material. In the gravelly silt loam plots, macropores located around rock fragments helped to minimize sealing effects. The addition of 0.5 cm of ash to the burned granitic plots resulted in a 20 mm hr-1 decrease in the final infiltration rate, and this was also probably due to surface sealing. However, the overall effect of ash addition was to increase the cumulative infiltration in proportion to the ash thickness and to maintain a higher average infiltration rate, indicating that while thin (<1 cm) ash layers may promote sealing, thicker ash layers help to reduce the runoff rate by providing additional storage for rainfall and by protecting the soil surface from raindrop impacts.

[Characteristics of floor litter and soil arthropod community in different types ot subtropical forest in Ailao Mountain of Yunnan, Southwest China].

PubMed

Yang, Zhao; Yang, Xiao-Dong

2011-11-01

By using line transect method, an investigation was conducted on the floor litter and soil arthropod community in a mid mountain wet evergreen broad-leaved forest, a mossy dwarf forest, and a Populus bonatii forest in Ailao Mountain of Yunnan in April (dry and hot season), June (rainy season), and December (dry and cold season), 2005. In both dry and rainy seasons, the existing floor litter mass, C storage, and C/N ratio in the three forests all increased in the order of mossy dwarf forest > P. bonatii forest > evergreen broad-leaved forest, but the N storage had less difference. In the floor litter layer of the forests, Acari and Collembola were the dominant groups of soil arthropod community, while Diptera larvae, Coleoptera, ants, and Homoptera were the common groups. The Sorenson coefficients of soil arthropod community in the three forests were extremely great. No significant differences were observed in the soil arthropod density (ind x m(-2)) in the floor litter layer among the three forests, but the relative density (ind x g(-1)) of soil arthropods was higher in the evergreen broad-leaved forest and P. bonatii forest than in the mossy dwarf forest. In the three forests, the density of soil arthropods was significantly higher in dry season than in rainy season, but the Shannon diversity index had less difference. There were significant positive correlations between the existing floor litter mass and the individual density (ind x m(-2)) and dominant groups of soil arthropod communities in dry and hot season (April), but negative correlations between the existing floor litter mass and the relative density (ind x g(-1)) of soil arthropod communities and Acari in dry and cold season (December). The individual densities of Collembola and Coleoptera also had positive correlations with the N storage of the existing floor litter mass in the three forests. It was considered that the floor litter and the development of soil arthropod community in the litter layer of the subtropical forests in Ailao Mountain had a close relation with the vegetation structure of the forests, and the individual density and the diversity of the soil arthropod community were controlled by the floor litter, whereas the environmental factors such as temperature and moisture in the forests also had obvious effects on the seasonal dynamics of the individual density of the soil arthropods.

Microbial properties and litter and soil nutrients after two prescribed fires in developing savannas in an upland Missouri Ozark Forest

Treesearch

Felix, Jr. Ponder; Mahasin Tadros; Edward F. Loewenstein

2009-01-01

On some landscapes periodic fire may be necessary to develop and maintain oak-dominated savannas. We studied the effects of two annual prescribed burns to determine their effect on microbial activity and soil and litter nutrients 1 year after the last burn. Surface litter and soil from the upper 0?5 cm soil layer in three developing savannas (oak-hickory, ...

Links between plant and fungal diversity in habitat fragments of coastal shrubland

DOE PAGES

Maltz, Mia R.; Treseder, Kathleen K.; McGuire, Krista L.

2017-09-19

Habitat fragmentation is widespread across ecosystems, detrimentally affecting biodiversity. Although most habitat fragmentation studies have been conducted on macroscopic organisms, microbial communities and fungal processes may also be threatened by fragmentation. This study investigated whether fragmentation, and the effects of fragmentation on plants, altered fungal diversity and function within a fragmented shrubland in southern California. Using fluorimetric techniques, we assayed enzymes from plant litter collected from fragments of varying sizes to investigate enzymatic responses to fragmentation. To isolate the effects of plant richness from those of fragment size on fungi, we deployed litter bags containing different levels of plant littermore » diversity into the largest fragment and incubated in the field for one year. Following field incubation, we determined litter mass loss and conducted molecular analyses of fungal communities. We found that leaf-litter enzyme activity declined in smaller habitat fragments with less diverse vegetation. Moreover, we detected greater litter mass loss in litter bags containing more diverse plant litter. Additionally, bags with greater plant litter diversity harbored greater numbers of fungal taxa. These findings suggest that both plant litter resources and fungal function may be affected by habitat fragmentation's constraints on plants, possibly because plant species differ chemically, and may thus decompose at different rates. Diverse plant assemblages may produce a greater variety of litter resources and provide more ecological niche space, which may support greater numbers of fungal taxa. Thus, reduced plant diversity may constrain both fungal taxa richness and decomposition in fragmented coastal shrublands. Altogether, our findings provide evidence that even fungi may be affected by human-driven habitat fragmentation via direct effects of fragmentation on plants. Our findings underscore the importance of restoring diverse vegetation communities within larger coastal sage scrub fragments and suggest that this may be an effective way to improve the functional capacity of degraded sites.« less

Links between plant and fungal diversity in habitat fragments of coastal shrubland

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maltz, Mia R.; Treseder, Kathleen K.; McGuire, Krista L.

Habitat fragmentation is widespread across ecosystems, detrimentally affecting biodiversity. Although most habitat fragmentation studies have been conducted on macroscopic organisms, microbial communities and fungal processes may also be threatened by fragmentation. This study investigated whether fragmentation, and the effects of fragmentation on plants, altered fungal diversity and function within a fragmented shrubland in southern California. Using fluorimetric techniques, we assayed enzymes from plant litter collected from fragments of varying sizes to investigate enzymatic responses to fragmentation. To isolate the effects of plant richness from those of fragment size on fungi, we deployed litter bags containing different levels of plant littermore » diversity into the largest fragment and incubated in the field for one year. Following field incubation, we determined litter mass loss and conducted molecular analyses of fungal communities. We found that leaf-litter enzyme activity declined in smaller habitat fragments with less diverse vegetation. Moreover, we detected greater litter mass loss in litter bags containing more diverse plant litter. Additionally, bags with greater plant litter diversity harbored greater numbers of fungal taxa. These findings suggest that both plant litter resources and fungal function may be affected by habitat fragmentation's constraints on plants, possibly because plant species differ chemically, and may thus decompose at different rates. Diverse plant assemblages may produce a greater variety of litter resources and provide more ecological niche space, which may support greater numbers of fungal taxa. Thus, reduced plant diversity may constrain both fungal taxa richness and decomposition in fragmented coastal shrublands. Altogether, our findings provide evidence that even fungi may be affected by human-driven habitat fragmentation via direct effects of fragmentation on plants. Our findings underscore the importance of restoring diverse vegetation communities within larger coastal sage scrub fragments and suggest that this may be an effective way to improve the functional capacity of degraded sites.« less

[Edge effects of forest gap in Pinus massoniana plantations on the decomposition of leaf litter recalcitrant components of Cinnamomum camphora and Toona ciliata.

PubMed

Zhang, Yan; Zhang, Dan Ju; Li, Xun; Liu, Hua; Zhang, Ming Jin; Yang, Wan Qin; Zhang, Jian

2016-04-22

The objective of the study was to evaluate the dynamics of recalcitrant components during foliar litter decomposition under edge effects of forest gap in Pinus massoniana plantations in the low hilly land, Sichuan basin. A field litterbag experiment was conducted in seven forest gaps with different sizes (100, 225, 400, 625, 900, 1225, 1600 m 2 ) which were generated by thinning P. massoniana plantations. The degradation rate of four recalcitrant components, i.e., condensed tannins, total phenol, lignin and cellulose in foliar litter of two native species (Cinnamomum camphora and Toona ciliata) at the gap edge and under the closed canopy were measured. The results showed that the degradation rate of recalcitrant components in T. ciliata litter except for cellulose at the gap edge were significantly higher than that under the closed canopy. For C. camphora litter, only the degradation of lignin at the gap edge was higher than that under the closed canopy. After one-year decomposition, four recalcitrant components in two types of foliar litter exhibited an increment of degradation rate, and the degradation rate of condensed tannin was the fastest, followed by total phenol and cellulose, but the lignin degradation rate was the slowest. With the increase of gap size, except for cellulose, the degradation rate ofthe other three recalcitrant components of the T. ciliata at the edge of medium sized gaps (400 and 625 m 2 ) were significantly higher than at the edge of other gaps. However, lignin in the C. camphora litter at the 625 m 2 gap edge showed the greatest degradation rate. Both temperature and litter initial content were significantly correlated with litter recalcitrant component degradation. Our results suggested that medium sized gaps (400-625 m 2 ) had a more significant edge effect on the degradation of litter recalcitrant components in the two native species in P. massoniana plantations, however, the effect also depended on species.

Plant n-alkane production from litterfall altered the diversity and community structure of alkane degrading bacteria in litter layer in lowland subtropical rainforest in Taiwan

NASA Astrophysics Data System (ADS)

Huang, Tung-Yi; Hsu, Bing-Mu; Chao, Wei-Chun; Fan, Cheng-Wei

2018-03-01

n-Alkane and alkane-degrading bacteria have long been used as crucial biological indicators of paleoecology, petroleum pollution, and oil and gas prospecting. However, the relationship between n-alkane and alkane-degrading bacteria in natural forests is still poorly understood. In this study, long-chain n-alkane (C14-C35) concentrations in litterfall, litter layer, and topsoil as well as the diversity and abundance of n-alkane-degrading bacterial communities in litter layers were investigated in three habitats across a lowland subtropical rainforest in southern Taiwan: ravine, windward, and leeward habitats in Nanjenshan. Our results demonstrate that the litterfall yield and productivity of long-chain n-alkane were highest in the ravine habitats. However, long-chain n-alkane concentrations in all habitats were decreased drastically to a similar low level from the litterfall to the bulk soil, suggesting a higher rate of long-chain n-alkane degradation in the ravine habitat. Operational taxonomic unit (OTU) analysis using next-generation sequencing data revealed that the relative abundances of microbial communities in the windward and leeward habitats were similar and different from that in the ravine habitat. Data mining of community amplicon sequencing using the NCBI database revealed that alkB-gene-associated bacteria (95 % DNA sequence similarity to alkB-containing bacteria) were most abundant in the ravine habitat. Empirical testing of litter layer samples using semi-quantitative polymerase chain reaction for determining alkB gene levels confirmed that the ravine habitat had higher alkB gene levels than the windward and leeward habitats. Heat map analysis revealed parallels in pattern color between the plant and microbial species compositions of the habitats, suggesting a causal relationship between the plant n-alkane production and microbial community diversity. This finding indicates that the diversity and relative abundance of microbial communities in the litter layer are affected by n-alkane plant composition in the litterfall.

Toward a Simple Framework for Understanding the Influence of Litter Quality on Vertical and Horizontal Patterns of Soil Organic Matter Pools

NASA Astrophysics Data System (ADS)

Craig, M.; Phillips, R.

2016-12-01

Decades of research have revealed that plant litter quality fundamentally influences soil organic matter (SOM) properties. Yet we lack the predictive frameworks necessary to up-scale our understanding of these dynamics in biodiverse systems. Given that ectomycorrhizal (EM) and arbuscular mycorrhizal (AM) plants are thought to differ in their litter quality, we ask whether this dichotomy represents a framework for understanding litter quality effects on SOM in temperate forests. To do this, we sampled soils from 250 spatially referenced locations within a 25-Ha plot where 28,000 trees had been georeferenced, and analyzed spatial patterns of plant and SOM properties. We then examined the extent to which the dominance of AM- versus EM-trees relates to 1) the quality of litter inputs to forest soils and 2) the horizontal and vertical distribution of SOM fractions. We found that leaf litters produced by EM-associated trees were generally of lower quality, having a lower concentration of soluble compounds and higher C:N. Concomitant with this, we observed higher soil C:N under EM trees. Interestingly, this reflected greater N storage in AM-dominated soils rather than greater C storage in EM-dominated soils. These patterns were driven by the storage of SOM in N-rich fractions in AM-dominated soils. Specifically, trees with high litter quality were associated with greater amounts of deep and mineral-associated SOM; pools that are generally considered stable. Our results support the recent contention that high-quality plant inputs should lead to the formation of stable SOM and suggest that the AM-EM framework may provide a way forward for representing litter quality effects on SOM in earth system models.

Effects of the Interception of Litterfall by the Understory on Carbon Cycling in Eucalyptus Plantations of South China

PubMed Central

Huang, Yuhui; Hui, Dafeng; Wen, Meili

2014-01-01

For the purposes of forest restoration, carbon (C) fixation, and economic improvement, eucalyptus (Eucalyptus urophylla) has been widely planted in South China. The understory of eucalyptus plantations is often occupied by a dense community of the fern Dicranopteris dichotoma, which intercepts tree canopy leaf litter before it reaches the ground. To understand the effects of this interception of litterfall on C cycling in eucalyptus plantations, we quantified the mass of intercepted litter and the influences of litterfall interception on litter decomposition and soil respiration. The total mass of E. urophylla litterfall collected on the understory was similar to that collected by the traditional litter trap method. All of the eucalyptus litterfall is intercepted by the D. dichotoma canopy. Of the litterfall that was intercepted by D. dichotoma, 20–40% and 60–80% was intercepted by the top (50–100 cm) and bottom (0–50 cm) of the understory canopy, respectively. Intercepted litterfall decomposed faster at the bottom of understory canopy (at the base of the plants) than at the top, and decomposition was slower on the soil surface in the absence of understory than on any location in the understory canopy. Soil respiration was highest when both the understory and litter were present and was lowest when both the understory and litter were absent. These results indicate that litterfall interception changed carbon flow between aboveground and belowground through litter decomposition and soil respiration, which changed carbon cycling in eucalyptus plantations. The effects of the understory on litter decomposition and soil respiration should be considered in ecosystem carbon models. PMID:24959853

Nutrients and temperature additively increase stream microbial respiration

Treesearch

David W. P. Manning; Amy D. Rosemond; Vladislav Gulis; Jonathan P. Benstead; John S. Kominoski

2017-01-01

Rising temperatures and nutrient enrichment are co‐occurring global‐change drivers that stimulate microbial respiration of detrital carbon, but nutrient effects on the temperature dependence of respiration in aquatic ecosystems remain uncertain. We measured respiration rates associated with leaf litter, wood, and fine benthic organic matter (FBOM) across...

Contrasting response of stream detritivores to long-term nutrient enrichment

Treesearch

W.F. Cross; B.R. Johnson; J.R. Wallace; A.D. Rosemond

2005-01-01

We examined growth and production responses of two dominant stream detritivores (chironomids and Tallaperla spp. stoneflies) at opposite ends of the "slow-fast" life-history continuum and with distinct feeding characteristics (i.e., consumption of fine particulate organic matter vs. leaf litter) to a 2-yr experimental nutrient enrichment of...

USING STABLE ISOTOPES TO IDENTIFY SOURCES OF ORGANIC AND INORGANIC PHOSPHOROUS AND NITROGEN IN THE TWIN CITIES WATERSHED

EPA Science Inventory

It is expected that human activity and terrestrial input (i.e., leaf litter, throughfall) will be the dominant sources of N and P, but that sources will vary greatly at small spatial scales. Preliminary work suggests that tree species cover, soil characteristics and snowmel...

Utilization of leaf litter as a potential feed source

USDA-ARS?s Scientific Manuscript database

Proximate analysis and In-situ nylon bag ruminal dry matter degradation of fall dropped Liriodendron tulipifera (tulip poplar) and Quercus alba (white oak) leaves were used to determine their potential use as a feed source for ruminant livestock animals. Ash content was 8.24 and 4.69 ...

Stevesaltica, a new genus of moss and leaf-litter inhabiting flea beetles from Bolivia (Coleoptera: Chrysomelidae: Galerucinae: Alticini)

USDA-ARS?s Scientific Manuscript database

A new genus (Stevesaltica) with two new species (S. normi and S. perdita) from Bolivia is described and illustrated. It is similar to Exoceras Jacoby. An identification key for all flea beetle genera known to occur in mosses in the Western Hemisphere is provided....

Effects of Chinese tallow leaf litter on water chemistry and surfacing behaviour of anuran larvae

Treesearch

Daniel Saenz; Cory K. Adams

2017-01-01

The establishment of exotic invasive species, including plants, has been linked to the decline of some amphibian populations. Of particular concern with invasive plants, from an amphibian conservation perspective, is that they are disproportionately wetland or riparian species. Recent evidence suggests that Chinese tallow (Triadica sebifera), an...

Long-term leaf production response to elevated atmospheric carbon dioxide and tropospheric ozone

Treesearch

Alan F. Talhelm; Kurt S. Pregitzer; Christian P. Giardina

2011-01-01

Elevated concentrations of atmospheric CO2 and tropospheric O3 will profoundly influence future forest productivity, but our understanding of these influences over the long-term is poor. Leaves are key indicators of productivity and we measured the mass, area, and nitrogen concentration of leaves collected in litter traps...

Response of nutrients, biofilm, and benthic insects to salmon carcass addition.

Treesearch

Shannon M. Claeson; Judith L. Li; Jana E. Compton; Peter A. Bisson

2006-01-01

Salmon carcass addition to streams is expected to increase stream productivity at multiple trophic levels. This study examined stream nutrient (nitrogen, phosphorus, and carbon), epilithic biofilm (ash-free dry mass and chlorophyll a), leaf-litter decomposition, and macroinvertebrate (density and biomass) responses to carcass addition in three headwater streams of...

Disease risk of potting media infested with Phytophthora ramorum under nursery conditions

Treesearch

S.A. Tjosvold; D.L. Chambers; E.J. Fichtner; S.T. Koike; S.R. Mori

2009-01-01

Phytophthora ramorum has been found in potting media of containerized plants; however, the role of infested media on disease development under nursery conditions is unknown. This study assesses pathogen survival, sporulation, and infectivity to rhododendron plants in nursery pots with infected leaf litter that were maintained under greenhouse and...

Comparison of degree-day accumulation models for prediciting spring reproductive populations of Lygus lineolaris (Palisot de Beauvois)

USDA-ARS?s Scientific Manuscript database

Tarnished plant bugs, Lygus lineolaris (Palisot de Beauvois), are a major pest of cotton throughout Mississippi and the Midsouth region. Adult L. lineolaris diapause and overwinter utilizing leaf litter and winter host plants. Degree day accumulation models were evaluated using six biofixes, four l...

Molecular markers indicate different dynamics of leaves and roots during litter decomposition

NASA Astrophysics Data System (ADS)

Altmann, Jens; Jansen, Boris; Palviainen, Marjo; Kalbitz, Karsten

2010-05-01

Up to now there is only a poor understanding of the sources contributing to organic carbon in forest soils, especially the contribution of leaves and roots. Studies of the last 2 decades have shown that methods like pyrolysis and CuO oxidation are suitable tools to trace back the main contributors of organic matter in water, sediments and soils. Lignin derived monomers, extractable lipids, cutin and suberin derived compounds have been used frequently for identification of plant material. However, for the selection of suitable biomarker the decomposition patterns and stability of these compounds are of high importance but they are only poorly understood. In this study we focused on following questions: (I) Which compounds are characteristic to identify certain plant parts and plant species? (II) How stable are these compounds during the first 3 years of litter decomposition? We studied the chemical composition of samples from a 3-year litterbag decomposition experiment with roots and leaves of spruce, pine and birch which was done in Finland. Additionally to mass loss, carbon and nitrogen contents, free lipids were extracted; by alkaline hydrolysis non extractable lipids were gained. The extracts were analyzed afterwards by GC-MS, the insoluble residues were analyzed by curie-point Pyrolysis GC-MS. In addition to the identification and quantification of a variety of different compounds and compound ratios we used statistical classification methods to get deeper insights into the patterns of leaf and root-derived biomarkers during litter decomposition. The mass loss was largely different between the litter species and we always observed larger mass loss for leaf-derived litter in comparison to root derived litter. This trend was also observed by molecular analysis. The increase of the ratio of vanillic acid to vanillin was correlated to the mass loss of the samples over time. This shows that the degree of decomposition of plant material was linked with the degree of lignin degradation. Preliminary results show, that we were able to distinguish the different species and plant parts using various approaches, e.g., abundance and patterns of different substances and different ratios of compounds. The polyesters suberin and cutin were particularly useful to differentiate between roots and leaves. We conclude that knowledge of the decomposition patterns of molecular markers will largely improve the identification power of organic matter sources in soils.

Pesticide impact on aquatic invertebrates identified with Chemcatcher® passive samplers and the SPEAR(pesticides) index.

PubMed

Münze, Ronald; Orlinskiy, Polina; Gunold, Roman; Paschke, Albrecht; Kaske, Oliver; Beketov, Mikhail A; Hundt, Matthias; Bauer, Coretta; Schüürmann, Gerrit; Möder, Monika; Liess, Matthias

2015-12-15

Pesticides negatively affect biodiversity and ecosystem function in aquatic environments. In the present study, we investigated the effects of pesticides on stream macroinvertebrates at 19 sites in a rural area dominated by forest cover and arable land in Central Germany. Pesticide exposure was quantified with Chemcatcher® passive samplers equipped with a diffusion-limiting membrane. Ecological effects on macroinvertebrate communities and on the ecosystem function detritus breakdown were identified using the indicator system SPEARpesticides and the leaf litter degradation rates, respectively. A decrease in the abundance of pesticide-vulnerable taxa and a reduction in leaf litter decomposition rates were observed at sites contaminated with the banned insecticide Carbofuran (Toxic Units≥-2.8), confirming the effect thresholds from previous studies. The results show that Chemcatcher® passive samplers with a diffusion-limiting membrane reliably detect ecologically relevant pesticide pollution, and we suggest Chemcatcher® passive samplers and SPEARpesticides as a promising combination to assess pesticide exposure and effects in rivers and streams. Copyright © 2015 Elsevier B.V. All rights reserved.

When things don't add up: quantifying impacts of multiple stressors from individual metabolism to ecosystem processing.

PubMed

Galic, Nika; Sullivan, Lauren L; Grimm, Volker; Forbes, Valery E

2018-04-01

Ecosystems are exposed to multiple stressors which can compromise functioning and service delivery. These stressors often co-occur and interact in different ways which are not yet fully understood. Here, we applied a population model representing a freshwater amphipod feeding on leaf litter in forested streams. We simulated impacts of hypothetical stressors, individually and in pairwise combinations that target the individuals' feeding, maintenance, growth and reproduction. Impacts were quantified by examining responses at three levels of biological organisation: individual-level body sizes and cumulative reproduction, population-level abundance and biomass and ecosystem-level leaf litter decomposition. Interactive effects of multiple stressors at the individual level were mostly antagonistic, that is, less negative than expected. Most population- and ecosystem-level responses to multiple stressors were stronger than expected from an additive model, that is, synergistic. Our results suggest that across levels of biological organisation responses to multiple stressors are rarely only additive. We suggest methods for efficiently quantifying impacts of multiple stressors at different levels of biological organisation. © 2018 John Wiley & Sons Ltd/CNRS.

High-frequency fire alters C : N : P stoichiometry in forest litter.

PubMed

Toberman, Hannah; Chen, Chengrong; Lewis, Tom; Elser, James J

2014-07-01

Fire is a major driver of ecosystem change and can disproportionately affect the cycling of different nutrients. Thus, a stoichiometric approach to investigate the relationships between nutrient availability and microbial resource use during decomposition is likely to provide insight into the effects of fire on ecosystem functioning. We conducted a field litter bag experiment to investigate the long-term impact of repeated fire on the stoichiometry of leaf litter C, N and P pools, and nutrient-acquiring enzyme activities during decomposition in a wet sclerophyll eucalypt forest in Queensland, Australia. Fire frequency treatments have been maintained since 1972, including burning every 2 years (2yrB), burning every 4 years (4 yrB) and no burning (NB). C : N ratios in freshly fallen litter were 29-42% higher and C : P ratios were 6-25% lower for 2 yrB than NB during decomposition, with correspondingly lower 2yrB N : P ratios (27-32) than for NB (34-49). Trends in litter soluble and microbial N : P ratios were similar to the overall litter N : P ratios across fire treatments. Consistent with these, the ratio of activities for N-acquiring to P-acquiring enzymes in litter was higher for 2 yrB than NB, whereas 4 yrB was generally intermediate between 2 yrB and NB. Decomposition rates of freshly fallen litter were significantly lower for 2 yrB (72 ± 2% mass remaining at the end of experiment) than for 4 yrB (59 ± 3%) and NB (62 ± 3%), a difference that may be related to effects of N limitation, lower moisture content, and/or litter C quality. Results for older mixed-age litter were similar to those for freshly fallen litter although treatment differences were less pronounced. Overall, these findings show that frequent fire (2 yrB) decoupled N and P cycling, as manifested in litter C : N : P stoichiometry and in microbial biomass N : P ratio and enzymatic activities. Furthermore, these data indicate that fire induced a transient shift to N-limited ecosystem conditions during the postfire recovery phase. © 2013 John Wiley & Sons Ltd.

Impact of lambda-cyhalothrin on a macroinvertebrate assemblage in outdoor experimental channels: implications for ecosystem functioning.

PubMed

Rasmussen, Jes Jessen; Friberg, Nikolai; Larsen, Soren E

2008-11-21

In this study, the impact of a single pulse of the pyrethroid lambda-cyhalothrin was tested on a macroinvertebrate assemblage consisting of Gammarus pulex, Leuctra nigra, Heptagenia sulphurea and Ancylus fluviatilis in outdoor experimental stream channels. Channels (4m long, 0.1m wide) were groundwater fed and had natural substratum. Macroinvertebrates were exposed to 10.65 or 106.5 ng L(-1) lambda cyhalothrin for 90 min in the laboratory and after 24h introduced to the experimental stream channels with four replicates of each treatment and controls. Drift samples were taken with 24-h interval for 10 days and behaviour of drifted macroinvertebrates was assessed. Microalgae biomass was measured on days 1, 5, 8 and 10 along with leaf litter decomposition using leaf packs of beech (Fagus sylvatica). Numbers of drifting G. pulex and L. nigra with reduced mobility increased significantly with concentration of lambda-cyhalothrin. Increase of algal biomass was significantly greater in stream channels with macroinvertebrates exposed to 106.5 ng L(-1) compared to controls and 10.65 ng L(-1) treatments. Accrual of microalgal biomass was significantly higher in the high concentration treatment and decomposition of leaf litter was significantly greater in control channels compared to channels with exposed macroinvertebrates. This study may apply valuable knowledge to the understanding and assessment of how pyrethroids impact ecosystem functioning in streams.