DEEP BIOSPHERE. Exploring deep microbial life in coal-bearing sediment down to ~2.5 km below the ocean floor.

PubMed

Inagaki, F; Hinrichs, K-U; Kubo, Y; Bowles, M W; Heuer, V B; Hong, W-L; Hoshino, T; Ijiri, A; Imachi, H; Ito, M; Kaneko, M; Lever, M A; Lin, Y-S; Methé, B A; Morita, S; Morono, Y; Tanikawa, W; Bihan, M; Bowden, S A; Elvert, M; Glombitza, C; Gross, D; Harrington, G J; Hori, T; Li, K; Limmer, D; Liu, C-H; Murayama, M; Ohkouchi, N; Ono, S; Park, Y-S; Phillips, S C; Prieto-Mollar, X; Purkey, M; Riedinger, N; Sanada, Y; Sauvage, J; Snyder, G; Susilawati, R; Takano, Y; Tasumi, E; Terada, T; Tomaru, H; Trembath-Reichert, E; Wang, D T; Yamada, Y

2015-07-24

Microbial life inhabits deeply buried marine sediments, but the extent of this vast ecosystem remains poorly constrained. Here we provide evidence for the existence of microbial communities in ~40° to 60°C sediment associated with lignite coal beds at ~1.5 to 2.5 km below the seafloor in the Pacific Ocean off Japan. Microbial methanogenesis was indicated by the isotopic compositions of methane and carbon dioxide, biomarkers, cultivation data, and gas compositions. Concentrations of indigenous microbial cells below 1.5 km ranged from <10 to ~10(4) cells cm(-3). Peak concentrations occurred in lignite layers, where communities differed markedly from shallower subseafloor communities and instead resembled organotrophic communities in forest soils. This suggests that terrigenous sediments retain indigenous community members tens of millions of years after burial in the seabed. Copyright © 2015, American Association for the Advancement of Science.

Effect of chronic nitrogen additions on soil nitrogen fractions in red spruce stands

USGS Publications Warehouse

David, M.B.; Cupples, A.M.; Lawrence, G.B.; Shi, G.; Vogt, K.; Wargo, P.M.

1998-01-01

The responses of temperate and boreal forest ecosystems to increased nitrogen (N) inputs have been varied, and the responses of soil N pools have been difficult to measure. In this study, fractions and pool sizes of N were determined in the forest floor of red spruce stands at four sites in the northeastern U.S. to evaluate the effect of increased N inputs on forest floor N. Two of the stands received 100 kg N ha-1 yr-1 for three years, one stand received 34 kg N ha-1 yr-1 for six years, and the remaining stand received only ambient N inputs. No differences in total N content or N fractions were measured in samples of the Oie and Oa horizons between treated and control plots in the three sites that received N amendments. The predominant N fraction in these samples was amino acid N (31-45 % of total N), followed by hydrolyzable unidentified N (16-31% of total N), acid- soluble N (18-22 % of total N), and NH4/+-N (9-13 % of total N). Rates of atmospheric deposition varied greatly among the four stands. Ammonium N and amino acid N concentrations in the Oie horizon were positively related to wet N deposition, with respective r2 values of 0.92 and 0.94 (n = 4, p < 0.05). These relationships were somewhat stronger than that observed between atmospheric wet N deposition and total N content of the forest floor, suggesting that these pools retain atmospherically deposited N. The NH4/+- N pool may represent atmospherically deposited N that is incorporated into organic matter, whereas the amino acid N pool could result from microbial immobilization of atmospheric N inputs. The response of forest floor N pools to applications of N may be masked, possibly by the large soil N pool, which has been increased by the long-term input of N from atmospheric deposition, thereby overwhelming the short-term treatments.

Trace-metal accumulation, distribution, and fluxes in forests of the northeastern United States

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

Friedland, A.J.

1985-01-01

Forest floor was sampled at 78 sites in nine northeastern states in the USA and analyzed for Cu, Zn, Ni, and Cd. Higher levels of trace metals occurred in the southern half of the study region. Earlier work identified that Pb accumulated in the forest floor of the high-elevation regions of New England. The distribution of Pb, Cu, Zn, Ni, and Cd within the forest floor was studied at three different forested states in New England. The greatest concentration of Pb, Cu, Zn, Ni, and Cd occurred in the Oe horizon of the forest floor in all three forests. Thismore » is the zone of greatest biological activity in the forest floor. Because it receives relatively high rates of atmospheric deposition, Camels Hump in northern Vermont was studied in greater detail. Lead concentration and amount in the forest floor increased between 550 and 1160 m elevation. Comparisons with 1966 and 1977 samples from the same stands showed that Pb, Cu, and Zn concentrations increased by as much as 148% in the intervening 14 years. Estimated deposition rates of Pb, Cu, and Zn based on accumulation rates agreed with regional deposition rates reported in the literature. Lead concentrations were an order of magnitude lower in mineral soil and vegetation than in forest floor. Thus the most likely source of forest floor Pb is the atmosphere. Lead was strongly retained by the forest floor and approximately 3% of the current Pb content of the forest floor is added each year by atmospheric deposition. At the current accumulation rates, the amount of Pb in the forest floor will double in three to four decades.« less

Biotic and abiotic factors regulating forest floor CO2 flux across a range of forest age classes in the southern Appalachians

Treesearch

James M. Vose; Paul V. Bolstad

2007-01-01

We measured forest floor CO2 flux in three age classes of forest in the southern Appalachians: 20-year-old, 85-year-old, and old-growth. Our objectives were to quantify differences in forest floor CO2 flux among age classes, and determine the relative importance of abiotic and biotic driving variables. Forest floor CO

A model of forest floor carbon mass for United States forest types

Treesearch

James E. Smith; Linda S. Heath

2002-01-01

Includes a large set of published values of forest floor mass and develop large-scale estimates of carbon mass according to region and forest type. Estimates of average forest floor carbon mass per hectare of forest applied to a 1997 summary forest inventory, sum to 4.5 Gt carbon stored in forests of the 48 contiguous United States.

Long-term changes in forest floor processes in southern Appalachian forests

Treesearch

Jennifer D. Knoepp; Barbara C. Reynolds; D.A. Crossley; Wayne T. Swank

2005-01-01

Soil nutrient concentrations decreased in an aggrading southern Appalachian forest over a 20-year period. Construction of nutrient budgets showed significant nutrient sequestration aboveground including increased forest floor mass. We hypothesized that the changes in forest floor mass resulted from decreased litter decomposition rates because of decreased litter...

The role of forest floor and trees to the ecosystem scale methane budget of boreal forests

NASA Astrophysics Data System (ADS)

Pihlatie, Mari; Halmeenmäki, Elisa; Peltola, Olli; Haikarainen, Iikka; Heinonsalo, Jussi; Santalahti, Minna; Putkinen, Anuliina; Fritze, Hannu; Urban, Otmar; Machacova, Katerina

2016-04-01

Boreal forests are considered as a sink of atmospheric methane (CH4) due to the activity of CH4 oxidizing bacteria (methanotrophs) in the soil. This soil CH4 sink is especially strong for upland forest soils, whereas forests growing on organic soils may act as small sources due to the domination of CH4 production by methanogens in the anaerobic parts of the soil. The role of trees to the ecosystem-scale CH4 fluxes has until recently been neglected due to the perception that trees do not contribute to the CH4 exchange, and also due to difficulties in measuring the CH4 exchange from trees. Findings of aerobic CH4 formation in plants and emissions from tree-stems in temperate and tropical forests during the past decade demonstrate that our understanding of CH4 cycling in forest ecosystems is not complete. Especially the role of forest canopies still remain unresolved, and very little is known of CH4 fluxes from trees in boreal region. We measured the CH4 exchange of tree-stems and tree-canopies from pine (Pinus sylvestris), spruce (Picea abies) and birch (Betula pubescens, Betula pendula) trees growing in Southern Finland (SMEAR II station) on varying soil conditions, from upland mineral soils to paludified soil. We compared the CH4 fluxes from trees to forest-floor CH4 exchange, both measured by static chambers, and to CH4 fluxes measured above the forest canopy by a flux gradient technique. We link the CH4 fluxes from trees and forest floor to physiological activity of the trees, such as transpiration, sap-flow, CO2 net ecosystem exchange (NEE), soil properties such as temperature and moisture, and to the presence of CH4 producing methanogens and CH4 oxidizing methanotrophs in trees or soil. The above canopy CH4 flux measurements show that the whole forest ecosystem was a small source of CH4 over extended periods in the spring and summer 2012, 2014 and 2015. Throughout the 2013-2014 measurements, the forest floor was in total a net sink of CH4, with variation between high CH4 uptake in the dominating dry upland areas and high emissions from the few wet spots of the forest. All the studied tree species emitted small amounts of CH4 from the stems and shoots, with emission rates depending on the season, tree species and soil conditions. Especially, CH4 emissions from birch canopies were high and can therefore contribute significantly to the ecosystem-scale CH4 fluxes. Processes behind the canopy and stem CH4emission remain unresolved, however, ongoing analysis of the methanogens and methanotrophs within the plant-soil systems will reveal whether CH4 production or consumption is of microbial origin. Also, comparison of the CH4 fluxes from trees and forest floor to sap-flow, transpiration, and NEE as well as soil parameters will help to explain the seasonality and mechanisms involved in the CH4 emissions.

Lack of viable seeds in the forest floor after clearcutting

Treesearch

Robert M. Frank; Lawrence O. Safford

1970-01-01

The viability of seeds o[ northern conifers apparently does not persist in the forest floor for more than one year. A set of forest-floor samples collected two years alter a heavy seed crop and one year alter a seedcrop failure did not produce any conifer germinants, regardless of whether or not the surfaces of the samples were disturbed. A second set of forest-floor...

Properties of dissolved and total organic matter in throughfall, stemflow and forest floor leachate of central European forests

NASA Astrophysics Data System (ADS)

Bischoff, S.; Schwarz, M. T.; Siemens, J.; Thieme, L.; Wilcke, W.; Michalzik, B.

2015-05-01

We present the first investigation of the composition of dissolved organic matter (DOM) compared to total organic matter (TOM, consisting of DOM, < 0.45 μm and particulate organic matter 0.45 μm < POM < 500 μm) in throughfall, stemflow and forest floor leachate of common beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) H. Karst.) forests using solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. We hypothesized that the composition and properties of organic matter (OM) in forest ecosystem water samples differ between DOM and TOM and between the two tree species. The 13C NMR results, derived from 21 samples, point to pronounced differences in the composition of DOM and TOM in throughfall solution at the beech sites, with TOM exhibiting higher relative intensities for the alkyl C region, which represents aliphatic C from less decomposed organic material compared to DOM. Furthermore, TOM shows lower intensities for lignin-derived and aromatic C of the aryl C region resulting in lower aromaticity indices and a diminished degree of humification. Across the ecosystem compartments, differences in the structural composition of DOM and TOM under beech lessened in the following order: throughfall > stemflow ≈ forest floor leachate. In contrast to the broadleaved sites, differences between DOM and TOM in throughfall solution under spruce were less pronounced and spectra were, overall, dominated by the alkyl C region, representing aliphatic C. Explanations of the reported results might be substantiated in differences in tree species-specific structural effects, leaching characteristics or differences in the microbial community of the tree species' phyllosphere and cortisphere. However, the fact that throughfall DOM under beech showed the highest intensities of recalcitrant aromatic and phenolic C among all samples analysed likely points to a high allelopathic potential of beech trees negatively affecting other organisms and hence ecosystem processes and functions.

Hydrologic and forest management controls on DOC dynamics in the small watersheds of the H.J. Andrews Experimental Forest, OR

NASA Astrophysics Data System (ADS)

Lajtha, K.; Jones, J. A.

2016-12-01

Dissolved organic carbon (DOC) export from hillslopes to streams is an important component of the carbon cycle of a catchment and may be a critical source of energy for the aquatic food web in receiving waters. Using a long-term record of DOC and other dissolved nutrients and elements from paired watersheds from the H.J. Andrews Experimental Forest in Oregon, we explored hydrologic, climatic, and land-use controls on seasonal and inter-annual patterns of DOC flux in a seasonally dry ecosystem. Seasonal patterns of DOC flux demonstrated source limitations to DOC export, with DOC concentrations highest immediately following the first rains after a dry summer, and lowest after winter rains. In contrast, more geochemically-controlled elements showed simple dilution-concentration patterns with no seasonal hysteresis. Inter-annual patterns of DOC flux, however, did not provide evidence of source limitation, with DOC flux within a watershed tightly correlated to total discharge but not temperature. Among watersheds, forest harvest, even over 50 years ago, significantly reduced DOC flux but not fluxes of other elements including N; this response was linked to the loading of coarse woody debris to the forest floor. Chemical fingerprinting of DOC revealed that old-growth watersheds had higher fluxes of DOC characteristic of forest floor organic materials, likely delivered to streams through more surficial preferential flow pathways not subject to microbial alteration, respiration, or sorption losses. Taken together these results suggest that the biogeochemical composition of forested streams reflects both current hydrologic patterns and also processes that occurred many decades ago within the catchment.

Redistribution of soil nitrogen, carbon and organic matter by mechanical disturbance during whole-tree harvesting in northern hardwoods

USGS Publications Warehouse

Ryan, D.F.; Huntington, T.G.; Wayne, Martin C.

1992-01-01

To investigate whether mechanical mixing during harvesting could account for losses observed from forest floor, we measured surface disturbance on a 22 ha watershed that was whole-tree harvested. Surface soil on each 10 cm interval along 81, randomly placed transects was classified immediately after harvesting as mineral or organic, and as undisturbed, depressed, rutted, mounded, scarified, or scalped (forest floor scraped away). We quantitatively sampled these surface categories to collect soil in which preharvest forest floor might reside after harvest. Mechanically mixed mineral and organic soil horizons were readily identified. Buried forest floor under mixed mineral soil occurred in 57% of mounds with mineral surface soil. Harvesting disturbed 65% of the watershed surface and removed forest floor from 25% of the area. Mechanically mixed soil under ruts with organic or mineral surface soil, and mounds with mineral surface soil contained organic carbon and nitrogen pools significantly greater than undisturbed forest floor. Mechanical mixing into underlying mineral soil could account for the loss of forest floor observed between the preharvest condition and the second growing season after whole-tree harvesting. ?? 1992.

Effects of the amount and composition of the forest floor on emergence and early establishment of loblolly pine seedlings

Treesearch

Michael G. Shelton

1995-01-01

Five forest floor weights (0, 10, 20, 30, and 40 MgJha), three forest floor compositions (pine, pine-hardwood, and hardwood), and two seed placements (forest floor and soil surface) were tested in a three-factorial. split-plot design with four incomplete, randomized blocks. The experiment was conducted in a nursery setting and used wooden frames to define 0.145-m

Singular and combined effects of blowdown, salvage logging, and wildfire on forest floor and soil mercury pools.

PubMed

Mitchell, Carl P J; Kolka, Randall K; Fraver, Shawn

2012-08-07

A number of factors influence the amount of mercury (Hg) in forest floors and soils, including deposition, volatile emission, leaching, and disturbances such as fire. Currently the impact on soil Hg pools from other widespread forest disturbances such as blowdown and management practices like salvage logging are unknown. Moreover, ecological and biogeochemical responses to disturbances are generally investigated within a single-disturbance context, with little currently known about the impact of multiple disturbances occurring in rapid succession. In this study we capitalize on a combination of blowdown, salvage logging and fire events in the sub-boreal region of northern Minnesota to assess both the singular and combined effects of these disturbances on forest floor and soil total Hg concentrations and pools. Although none of the disturbance combinations affected Hg in mineral soil, we did observe significant effects on both Hg concentrations and pools in the forest floor. Blowdown increased the mean Hg pool in the forest floor by 0.76 mg Hg m(-2) (223%). Salvage logging following blowdown created conditions leading to a significantly more severe forest floor burn during wildfire, which significantly enhanced Hg emission. This sequence of combined events resulted in a mean loss of approximately 0.42 mg Hg m(-2) (68% of pool) from the forest floor, after conservatively accounting for potential losses via enhanced soil leaching and volatile emissions between the disturbance and sampling dates. Fire alone or blowdown followed by fire did not significantly affect the total Hg concentrations or pools in the forest floor. Overall, unexpected consequences for soil Hg accumulation and by extension, atmospheric Hg emission and risk to aquatic biota, may result when combined impacts are considered in addition to singular forest floor and soil disturbances.

Soil nitrogen cycling and nitrous oxide flux in a Rocky Mountain Douglas-fir forest - Effects of fertilization, irrigation and carbon addition

NASA Technical Reports Server (NTRS)

Matson, Pamela A.; Gower, Stith T.; Volkmann, Carol; Billow, Christine; Grier, Charles C.

1992-01-01

Nitrous oxide fluxes and soil nitrogen transformations were measured in experimentally-treated high elevation Douglas-fir forests in northwestern New Mexico, USA. On an annual basis, forests that were fertilized with 200 kg N/ha emitted an average of 0.66 kg/ha of N2O-N, with highest fluxes occurring in July and August when soils were both warm and wet. Control, irrigated, and woodchip treated plots did not differ, and annual average fluxes ranged from 0.03 to 0.23 kg/ha. Annual net nitrogen mineralization and nitrate production were estimated in soil and forest floor using in situ incubations; fertilized soil mineralized 277 kg/ha/y in contrast to 18 kg/ha/y in control plots. Relative recovery of 15NH4-N applied to soil in laboratory incubations was principally in the form of NO3-N in the fertilized soils, while recovery was mostly in microbial biomass-N in the other treatments. Fertilization apparently added nitrogen that exceeded the heterotrophic microbial demand, resulting in higher rates of nitrate production and higher nitrous oxide fluxes. Despite the elevated nitrous oxide emission resulting from fertilization, we estimate that global inputs of nitrogen into forests are not currently contributing significantly to the increasing concentrations of nitrous oxide in the atmosphere.

[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.

Using hyperspectral imagery to estimate forest floor consumption from wildfire in boreal forests of Alaska, USA

Treesearch

Sarah A. Lewis; Andrew T. Hudak; Roger D. Ottmar; Peter R. Robichaud; Leigh B. Lentile; Sharon M. Hood; James B. Cronan; Penny Morgan

2011-01-01

Wildfire is a major forest disturbance in interior Alaska that can both directly and indirectly alter ecological processes. We used a combination of pre- and post-fire forest floor depths and post-fire ground cover assessments measured in the field, and high-resolution airborne hyperspectral imagery, to map forest floor conditions after the 2004 Taylor Complex in...

The distribution of mercury in a forest floor transect across the central United States

Treesearch

Charles H. (Hobie) Perry; Michael C. Amacher; William Cannon; Randall K. Kolka; Laurel Woodruff

2009-01-01

Mercury (Hg) stored in soil organic matter may be released when the forest floor is consumed by fire. Our objective is to document the spatial distribution of forest floor Hg for a transect crossing the central United States. Samples collected by the Forest Service, U.S. Department of Agriculture's Forest Inventory and Analysis Soil Quality Indicator were tested...

Longevity of black cherry seed in the forest floor

Treesearch

G. W. Wendel

1972-01-01

Observations made on the Fernow Experimental Forest in West Virginia indicate that some black cherry seeds remain viable in the forest floor over three winters. On the average fewer than 10 percent of the seeds stored in the forest floor germinated the first spring, about 50 percent germinated the second spring, and 25 percent germinated the third spring.

The distribution of nitrogen and phosphorus in forest floor layers of oak-hickory forests of varying productivity

Treesearch

Karyn S. Rodkey; Donald J. Kaczmarek; Phillip E. Pope

1995-01-01

The forest floor plays a major role in the storage and recycling of nutrients which, in turn, are important in maintaining the growth and productivity of forest ecosystems. The development of forest floor organic layers as influenced by litter quality and site quality is unclear. Previous studies in this lab have shown that the size and distribution of available...

Longer-term effects of selective thinning on microarthropod communities in a late-successional coniferous forest

USGS Publications Warehouse

Peck, R.W.; Niwa, C.G.

2005-01-01

Microarthropod densities within late-successional coniferous forests thinned 16-41 yr before sampling were compared with adjacent unthinned stands to identify longer term effects of thinning on this community. Soil and forest floor layers were sampled separately on eight paired sites. Within the forest floor oribatid, mesostigmatid, and to a marginal extent, prostigmatid mites, were reduced in thinned stands compared with unthinned stands. No differences were found for Collembola in the forest floor or for any mite suborder within the soil. Family level examination of mesostigmatid and prostigmatid mites revealed significant differences between stand types for both horizons. At the species level, thinning influenced numerous oribatid mites and Collembola. For oribatid mites, significant or marginally significant differences were found for seven of 15 common species in the forest floor and five of 16 common species in soil. Collembola were affected less, with differences found for one of 11 common species in the forest floor and three of 13 common species in soil. Multivariate analysis of variance and ordination indicated that forest thinning had little influence on the composition of oribatid mite and collembolan communities within either the forest floor or soil. Differences in microclimate or in the accumulation of organic matter on the forest floor were likely most responsible for the observed patterns of abundance. Considering the role that microarthropods play in nutrient cycling, determining the functional response of a wide range of taxa to thinning may be important to effective ecosystem management.

Forest floor fuels in red and jack pine stands

Treesearch

James K. Brown

1966-01-01

An investigation to determine the quantity and density of forest floor fuels in red pine (Pinus resinosa Ait.) and jack pine (Pinus banksiana Lamb.) stands was conducted on National Forests in Michigan and Minnesota. The study was designed to answer three questions: How much fuel per acre exits in individual layers of the forest floor? How reliably can weight of...

Spectral analysis of coniferous foliage and possible links to soil chemistry: are spectral chlorophyll indices related to forest floor dissolved organic C and N?

PubMed

Albrechtova, Jana; Seidl, Zdenek; Aitkenhead-Peterson, Jacqueline; Lhotáková, Zuzana; Rock, Barrett N; Alexander, Jess E; Malenovský, Zbynek; McDowell, William H

2008-10-15

Dissolved organic matter in soils can be predicted from forest floor C:N ratio, which in turn is related to foliar chemistry. Little is known about the linkages between foliar constituents such as chlorophylls, lignin, and cellulose and the concentrations of water-extractable forest floor dissolved organic carbon and dissolved organic nitrogen. Lignin and cellulose are not mobile in foliage and thus may be indicative of growing conditions during prior years, while chlorophylls respond more rapidly to the current physiological status of a tree and reflect nutrient availability. The aim of this study was to examine potential links among spectral foliar data, and the organic C and N of forest soils. Two coniferous species (red spruce and balsam fir) were studied in the White Mountains of New Hampshire, USA. Six trees of each species were sampled at 5 watersheds (2 in the Hubbard Brook Experimental Forest, 3 in the Bartlett Experimental Forest). We hypothesized that in a coniferous forest, chemistry of old foliage would better predict the chemical composition of the forest floor litter layer than younger foliage, which is the more physiologically active and the most likely to be captured by remote sensing of the canopy. Contrary to our expectations, chlorophyll concentration of young needles proved to be most tightly linked to soil properties, in particular water-extractable dissolved organic carbon. Spectral indices related to the chlorophyll content of needles could be used to predict variation in forest floor dissolved organic carbon and dissolved organic nitrogen. Strong correlations were found between optical spectral indices based on chlorophyll absorption and forest floor dissolved organic carbon, with higher foliage chlorophyll content corresponding to lower forest floor dissolved organic carbon. The mechanisms behind these correlations are uncertain and need further investigation. However, the direction of the linkage from soil to tree via nutrient availability is hypothesized based on negative correlations found between foliar N and forest floor dissolved organic carbon.

Changes in Organic Matter And Nutrients in Forest Floor After Applying Several Reproductive Cutting Methods in Shortleaf Pine-Hardwood Stands

Treesearch

Hal O. Liechty; Michael G. Shelton

2004-01-01

Abstract - This study was initiated to determine the effects of various regeneration cutting methods on forest floor mass and nutrient content in shortleaf pine-hardwood communities in the Ouachita and Ozark National Forests. Clearcutting generally altered forest floor concentrations of N, P, and S as well as loss on ignition by increasing the amount...

Branchfall as a Demographic Filter for Epiphyte Communities: Lessons from Forest Floor-Based Sampling

PubMed Central

Sarmento Cabral, Juliano; Petter, Gunnar; Mendieta-Leiva, Glenda; Wagner, Katrin; Zotz, Gerhard; Kreft, Holger

2015-01-01

Local variation in the abundance and richness of vascular epiphytes is often attributed to environmental characteristics such as substrate and microclimate. Less is known, however, about the impacts of tree and branch turnover on epiphyte communities. To address this issue, we surveyed branches and epiphytes found on the forest floor in 96 transects in two forests (Atlantic rainforest in Brazil and Caribbean rainforest in Panama). In the Brazilian forest, we additionally distinguished between edge and core study sites. We quantified branch abundance, epiphyte abundance, richness and proportion of adults to investigate the trends of these variables over branch diameter. Branches <2 cm in diameter comprised >90% of all branches on the forest floor. Abundance and richness of fallen epiphytes per transect were highest in the Brazilian core transects and lowest in the Panamanian transects. The majority of epiphytes on the floor (c. 65%) were found attached to branches. At all three study sites, branch abundance and branch diameter were negatively correlated, whereas epiphyte abundance and richness per branch, as well as the proportion of adults were positively correlated with branch diameter. The relationship between branch diameter and absolute epiphyte abundance or richness differed between study sites, which might be explained by differences in forest structure and dynamics. In the Panamanian forest, epiphytes had been previously inventoried, allowing an evaluation of our surveying method by comparing canopy and forest floor samplings. Individuals found on the forest floor corresponded to 13% of all individuals on branches <10 cm in diameter (including crowns), with abundance, richness and composition trends on forest floor reflecting canopy trends. We argue that forest floor surveys provide useful floristic and, most notably, demographic information particularly on epiphytes occurring on the thinnest branches, which are least accessible. Here, branchfall acts as an important demographic filter structuring epiphyte communities. PMID:26083417

Forest Floor Characteristics in Southwestern Wisconsin

Treesearch

M. Dean Knighton

1970-01-01

Percent slope, aspect, topographic position, and crown closure were found to have no significant influence on forest floor depth in southwestern Wisconsin. However, a significant decrease in forest floor depth and an increase in soil compaction were found on currently grazed slopes. Yet when grazing is stopped recovery is apperently quick with no permanent damage....

Nitrous oxide fluxes from forest floor, tree stems and canopies of boreal tree species during spring

NASA Astrophysics Data System (ADS)

Haikarainen, Iikka; Halmeenmäki, Elisa; Machacova, Katerina; Pihlatie, Mari

2017-04-01

Boreal forests are considered as small sources of atmospheric nitrous oxide (N2O) due to microbial N2O production in the soils. Recent evidence shows that trees may play an important role in N2O exchange of forest ecosystems by offering pathways for soil produced N2O to the atmosphere. To confirm magnitude, variability and the origin of the tree mediated N2O emissions more research is needed, especially in boreal forests which have been in a minority in such investigation. We measured forest floor, tree stem and shoot N2O exchange of three boreal tree species at the beginning of the growing season (13.4.-13.6.2015) at SMEAR II station in Hyytiälä, located in Southern Finland (61˚ 51´N, 24˚ 17´E, 181 a.s.l.). The fluxes were measured in silver birch (Betula pendula), downy birch (B. pubescens) and Norway spruce (Picea abies) on two sites with differing soil type and characteristics (paludified and mineral soil), vegetation cover and forest structure. The aim was to study the vertical profile of N2O fluxes at stem level and to observe temporal changes in N2O fluxes over the beginning of the growing season. The N2O exchange was determined using the static chamber technique and gas chromatographic analyses. Scaffold towers were used for measurements at multiple stem heights and at the canopy level. Overall, the N2O fluxes from the forest floor and trees at both sites were very small and close to the detection limit. The measured trees mainly emitted N2O from their stems and shoots, while the forest floor acted as a sink of N2O at the paludified site and as a small source of N2O at the mineral soil site. Stem emissions from all the trees at both sites were on average below 0.5 μg N2O m-2 of stem area h-1, and the shoot emissions varied between 0.2 and 0.5 ng N2O m-2 g-1 dry biomass. When the N2O fluxes were scaled up to the whole forest ecosystem, based on the tree biomass and stand density, the N2O emissions from birch and spruce trees at the paludified site were 1.4 and 2.2 mg N2O ha-1 h-1, respectively, while the forest floor was a sink of -6.1 mg N2O ha-1 h-1. At the mineral soil site the upscaled N2O emissions from birch trees and forest floor were 3.6 and 8.9 mg N2O ha-1 h-1, respectively, indicating that the emissions from trees significantly contribute to the N2O emissions from boreal forests. The results also indicate that tree canopies contributed up to 89% of the whole-tree N2O emissions. Our findings demonstrate that we urgently need more studies focusing on leaf-level N2O exchange in forest ecosystems. Acknowledgement This research was financially supported by the National Programme for Sustainability I (LO1415), Czech Science Foundation (17-18112Y), ENVIMET (CZ.1.07/2.3.00/20.0246) , Emil Aaltonen Foundation, Academy of Finland Research Fellow projects (292699, 263858, 288494), The Academy of Finland Centre of Excellence (projects 1118615, 272041), and ICOS-Finland (281255). We thank Hyytiälä SMEAR II station staff and Marek Jakubik for technical support.

Changes in water extractable organic matter during incubation of forest floor material in the presence of quartz, goethite and gibbsite surfaces

NASA Astrophysics Data System (ADS)

Heckman, Katherine; Vazquez-Ortega, Angelica; Gao, Xiaodong; Chorover, Jon; Rasmussen, Craig

2011-08-01

The release of dissolved organic matter (DOM) from forest floor material constitutes a significant flux of C to the mineral soil in temperate forest ecosystems, with estimates on the order of 120-500 kg C ha -1 year -1. Interaction of DOM with minerals and metals results in sorptive fractionation and stabilization of OM within the soil profile. Iron and aluminum oxides, in particular, have a significant effect on the quantity and quality of DOM transported through forest soils due to their high surface area and the toxic effects of dissolved aluminum on microbial communities. We directly examined these interactions by incubating forest floor material, including native microbiota, for 154 days in the presence of (1) goethite (α-FeOOH), (2) gibbsite (γ-Al(OH) 3), and (3) quartz (α-SiO 2) sand (as a control). Changes in molecular and thermal properties of water extractable organic matter (WEOM, as a proxy for DOM) were evaluated. WEOM was harvested on days 5, 10, 20, 30, 60, 90, and 154, and examined by thermogravimetry/differential thermal analysis (TG/DTA) and diffuse reflectance Fourier transform infrared (DRIFT) spectroscopy. Results indicated significant differences in WEOM quality among treatments, though the way in which oxide surfaces influenced WEOM properties did not seem to change significantly with increasing incubation time. Dissolved organic C concentrations were significantly lower in WEOM from the oxide treatments in comparison to the control treatment. Incubation with goethite produced WEOM with mid-to-high-range thermal lability that was depleted in both protein and fatty acids relative to the control. The average enthalpy of WEOM from the goethite treatment was significantly higher than either the gibbsite or control treatment, suggesting that interaction with goethite surfaces increases the energy content of WEOM. Incubation with gibbsite produced WEOM rich in thermally recalcitrant and carboxyl-rich compounds in comparison to the control treatment. These data indicate that interaction of WEOM with oxide surfaces significantly influences the composition of WEOM and that oxides play an important role in determining the biogeochemistry of forest soil DOM.

Longevity of Black Cherry, Wild Grape, and Sassafras Seed in the Forest Floor

Treesearch

G.W. Wendel

1977-01-01

The results of this study show that (1) black cherry seed remains viable in the forest floor for 3 years, with a small amount of seed germinating after 4 or 5 years; (2) sassafras seed remains viable for 6 years in the forest floor, and (3) some wild grape seed retains its viability for at least 8 years. These results are important to the forest manager in setting up...

Electrochemical properties of electrodes with different shapes and diffusion kinetic analysis of microbial fuel cells on ocean floor

NASA Astrophysics Data System (ADS)

Fu, Yubin; Liu, Jia; Su, Jia; Zhao, Zhongkai; Liu, Yang; Xu, Qian

2012-03-01

Microbial fuel cell (MFC) on the ocean floor is a kind of novel energy- harvesting device that can be developed to drive small instruments to work continuously. The shape of electrode has a great effect on the performance of the MFC. In this paper, several shapes of electrode and cell structure were designed, and their performance in MFC were compared in pairs: Mesh (cell-1) vs. flat plate (cell-2), branch (cell-3) vs. cylinder (cell-4), and forest (cell-5) vs. disk (cell-6) FC. Our results showed that the maximum power densities were 16.50, 14.20, 19.30, 15.00, 14.64, and 9.95 mWm-2 for cell-1, 2, 3, 4, 5 and 6 respectively. And the corresponding diffusion-limited currents were 7.16, 2.80, 18.86, 10.50, 18.00, and 6.900 mA. The mesh and branch anodes showed higher power densities and much higher diffusion-limited currents than the flat plate and the cylinder anodes respectively due to the low diffusion hindrance with the former anodes. The forest cathode improved by 47% of the power density and by 161% of diffusion-limited current than the disk cathode due to the former's extended solid/liquid/gas three-phase boundary. These results indicated that the shape of electrode is a major parameter that determining the diffusion-limited current of an MFC, and the differences in the electrode shape lead to the differences in cell performance. These results would be useful for MFC structure design in practical applications.

Post-fire comparisons of forest floor and soil carbon, nitrogen, and mercury pools with fire severity indices

Treesearch

Randy Kolka; Brian Sturtevant; Philip Townsend; Jessica Miesel; Peter Wolter; Shawn Fraver; Tom DeSutter

2014-01-01

Forest fires are important contributors of C, N, and Hg to the atmosphere. In the fall of 2011, a large wildfire occurred in northern Minnesota and we were able to quickly access the area to sample the forest floor and mineral soil for C, N, and Hg pools. When compared with unburned reference soils, the mean loss of C resulting from fire in the forest floor and the...

Sound absorption characteristics of tree bark and forest floor

Treesearch

G. Reethof; O. H. McDaniel; G. M. Heisler

1977-01-01

Results of basic research on absorption of sound by tree bark and forest floors are presented. Amount of sound absorption by tree bark was determined by laboratory experiments with bark samples in a standing-wave tube. A modified portable standing-wave tube was used to measure absorption of sound by forest floors with different moisture contents, with and without leaf...

Jack Pine and Aspen Forest Floors in Northeastern Minnesota

Treesearch

Robert M. Loomis

1977-01-01

Characteristics of upland forest floors under mature jack pine and aspen in northeastern Minnesota were investigated. These fuel measurements were needed as inputs for fire behavior prediction models -- useful for fire management decisions. The forest floor weight averaged 33,955 kg/ha and depth averaged 7.1 cm. Bulk density averaged 17 kg/m3 for the L (litter)...

Interactions with successional stage and nutrient status determines the life-form-specific effects of increased soil temperature on boreal forest floor vegetation.

PubMed

Hedwall, Per-Ola; Skoglund, Jerry; Linder, Sune

2015-02-01

The boreal forest is one of the largest terrestrial biomes and plays a key role for the global carbon balance and climate. The forest floor vegetation has a strong influence on the carbon and nitrogen cycles of the forests and is sensitive to changes in temperature conditions and nutrient availability. Additionally, the effects of climate warming on forest floor vegetation have been suggested to be moderated by the tree layer. Data on the effects of soil warming on forest floor vegetation from the boreal forest are, however, very scarce. We studied the effects on the forest floor vegetation in a long-term (18 years) soil warming and fertilization experiment in a Norway spruce stand in northern Sweden. During the first 9 years, warming favored early successional species such as grasses and forbs at the expense of dwarf shrubs and bryophytes in unfertilized stands, while the effects were smaller after fertilization. Hence, warming led to significant changes in species composition and an increase in species richness in the open canopy nutrient limited forest. After another 9 years of warming and increasing tree canopy closure, most of the initial effects had ceased, indicating an interaction between forest succession and warming. The only remaining effect of warming was on the abundance of bryophytes, which contrary to the initial phase was strongly favored by warming. We propose that the suggested moderating effects of the tree layer are specific to plant life-form and conclude that the successional phase of the forest may have a considerable impact on the effects of climate change on forest floor vegetation and its feedback effects on the carbon and nitrogen cycles, and thus on the climate.

Interactions with successional stage and nutrient status determines the life-form-specific effects of increased soil temperature on boreal forest floor vegetation

PubMed Central

Hedwall, Per-Ola; Skoglund, Jerry; Linder, Sune

2015-01-01

The boreal forest is one of the largest terrestrial biomes and plays a key role for the global carbon balance and climate. The forest floor vegetation has a strong influence on the carbon and nitrogen cycles of the forests and is sensitive to changes in temperature conditions and nutrient availability. Additionally, the effects of climate warming on forest floor vegetation have been suggested to be moderated by the tree layer. Data on the effects of soil warming on forest floor vegetation from the boreal forest are, however, very scarce. We studied the effects on the forest floor vegetation in a long-term (18 years) soil warming and fertilization experiment in a Norway spruce stand in northern Sweden. During the first 9 years, warming favored early successional species such as grasses and forbs at the expense of dwarf shrubs and bryophytes in unfertilized stands, while the effects were smaller after fertilization. Hence, warming led to significant changes in species composition and an increase in species richness in the open canopy nutrient limited forest. After another 9 years of warming and increasing tree canopy closure, most of the initial effects had ceased, indicating an interaction between forest succession and warming. The only remaining effect of warming was on the abundance of bryophytes, which contrary to the initial phase was strongly favored by warming. We propose that the suggested moderating effects of the tree layer are specific to plant life-form and conclude that the successional phase of the forest may have a considerable impact on the effects of climate change on forest floor vegetation and its feedback effects on the carbon and nitrogen cycles, and thus on the climate. PMID:25750720

Distribution of parquet flooring during 1969

Treesearch

William C. Miller; William C. Miller

1972-01-01

This is the third in a series of papers dealing with the residential and commercial hardwood flooring industry. The first two paper are: PHYSICAL DISTRIBUTIOONF OAK STRIP FLOORING IN 1969 (U.S.D.A. Forest Serv. Res. Paper NE-207) and DISTRIBUTION OF MAPLE STRIP FLOORING IN 1969. (U.S.D.A. Forest Serv. Res. Paper NE-215).

Changes in conifer and deciduous forest foliar and forest floor chemistry and basal area tree growth across a nitrogen (N) deposition gradient in the northeastern US

Treesearch

Johnny L. Boggs; Steven G. McNulty; Linda H. Pardo

2007-01-01

We evaluated foliar and forest floor chemistry across a gradient of N deposition in the Northeast at 11 red spruce (Picea rubens Sarg.) sites in 1987/1988 and foliar and forest floor chemistry and basal area growth at six paired spruce and deciduous sites in 1999. The six red spruce plots were a subset of the original 1987/1988 spruce sites. In 1999...

Control of depth to permafrost and soil temperature by the forest floor in black spruce/feathermoss communities.

Treesearch

C.T. Dyrness

1982-01-01

Changes in depth to permafrost and soil temperature were investigated for 4 years after treatment of the forest floor on small plots by fire and mechanical removal of half the forest floor layer and the entire layer. The only treatments to show a consistent, statistically significant effect were the mechanical removals. Fire treatments usually did not have a...

The role of litterfall in transferring Fukushima-derived radiocesium to a coniferous forest floor.

PubMed

Teramage, Mengistu T; Onda, Yuichi; Kato, Hiroaki; Gomi, Takashi

2014-08-15

The deposition of Fukushima-derived radiocesium via falling litter in a coniferous forest 180 km downwind immediately following the nuclear power plant accident was investigated. The litterfall contribution to the transfer of radiocesium from the forest canopy to the forest floor was determined, and this pathway was compared with hydrological pathways. The results demonstrated that during the observation period, a total of approximately 5.5 kBq m(-2) of Fukushima-derived radiocesium was deposited on the forest floor through throughfall (53%), stemflow (2.3%) and litterfall (45%) routes. The data revealed that the contributions of hydrological pathways became less important as time passed. However, the litterfall route, which transferred approximately 31% (2.5±0.6 kBq m(-2)) of the local fallout within the observation period, continued depositing radiocesium onto the forest floor. Copyright © 2014 Elsevier B.V. All rights reserved.

Effects of elevated CO2 and temperature on forest floor litter decomposition and chemistry

EPA Science Inventory

Forest floor can be a major component of the carbon held in forested soils. In mature forests it represents the balance between additions and decomposition under current climate conditions. Because of its position at the soil surface, this reservoir of C is highly susceptible...

Forest floor leachate fluxes under six different tree species on a metal contaminated site.

PubMed

Van Nevel, Lotte; Mertens, Jan; De Schrijver, An; Baeten, Lander; De Neve, Stefaan; Tack, Filip M G; Meers, Erik; Verheyen, Kris

2013-03-01

Trees play an important role in the biogeochemical cycling of metals, although the influence of different tree species on the mobilization of metals is not yet clear. This study examined effects of six tree species on fluxes of Cd, Zn, DOC, H(+) and base cations in forest floor leachates on a metal polluted site in Belgium. Forest floor leachates were sampled with zero-tension lysimeters in a 12-year-old post-agricultural forest on a sandy soil. The tree species included were silver birch (Betula pendula), oak (Quercus robur and Q. petraea), black locust (Robinia pseudoacacia), aspen (Populus tremula), Scots pine (Pinus sylvestris) and Douglas fir (Pseudotsuga menziesii). We show that total Cd fluxes in forest floor leachate under aspen were slightly higher than those in the other species' leachates, yet the relative differences between the species were considerably smaller when looking at dissolved Cd fluxes. The latter was probably caused by extremely low H(+) amounts leaching from aspen's forest floor. No tree species effect was found for Zn leachate fluxes. We expected higher metal leachate fluxes under aspen as its leaf litter was significantly contaminated with Cd and Zn. We propose that the low amounts of Cd and Zn leaching under aspen's forest floor were possibly caused by high activity of soil biota, for example burrowing earthworms. Furthermore, our results reveal that Scots pine and oak were characterized by high H(+) and DOC fluxes as well as low base cation fluxes in their forest floor leachates, implying that those species might enhance metal mobilization in the soil profile and thus bear a potential risk for belowground metal dispersion. Copyright © 2013 Elsevier B.V. All rights reserved.

Effects of the Forest Floor and Acorn Placement on Establishment and Early Development of Water Oak Seedlings

Treesearch

Yanfei Guo; Michael G. Shelton; B.R. Lockhart

1999-01-01

Effects of the forest floor (0, 10, 20, 30,40, and 50 Mg/ha) and acorn placement (buried 1.5 cm below the soil surface, pressed into the soil surface, and placed within the forest floor) on establishment and early development of water oak (Quercus nigra L.) seedlings were tested in a 6 x 3 factorial study in southeastern Arkansas. Increasing...

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...

Some Forest Floor Fuelbed Characteristics of Black Oak Stands in Southeast Missouri

Treesearch

John S. Crosby; Robert M. Loomis

1974-01-01

Black oak forest floor fuelbeds under 20 - and 40-year-old stands in southeast Missouri averaged 6.4 and 4.2 inches in depth, respectively. Loose Litter averaged 2.0 and 2.9 tons per acre and 3.3 inces in depth. Bulk density of litter averaged 0.33 and 0.49 lb/ft3 and of total forest floor 0.89 and 1.10 lbs/ft3, respectively.

Seasonal relationships between precipitation, forest floor, and streamwater nitrogen, Isle Royale, Michigan

USGS Publications Warehouse

Stottlemyer, R.; Toczydlowski, D.

1999-01-01

The Upper Great Lakes receive large amounts of precipitation-NH4/+ and moderate NO3/- inputs. Increased atmospheric inorganic N input has led to concern about ecosystem capacity to utilize excess N. This paper summarizes a 5-yr study of seasonal N content and flux in precipitation, snowpack, forest floor, and streamwater in order to assess the source of inorganic N outputs in streamflow from a small boreal watershed. Average precipitation N input was 3 kg ha-1 yr-1. The peak snowpack N content averaged 0.55 kg ha-1. The forest floor inorganic N pool was ???2 kg ha-1, eight times larger than monthly precipitation N input. The inorganic N pool size peaked in spring and early summer. Ninety percent of the forest floor inorganic N pool was made up of NH4/+-N. Forest floor inorganic N pools generally increased with temperature. Net N mineralization was 15 kg ha-1 yr-1, and monthly rates peaked in early summer. During winter, the mean monthly net N mineralization rate was twice the peak snowpack N content. Streamwater NO3/- concentration peaked in winter, and inorganic N output peaked in late fall. Beneath the dominant boreal forest species, net N mineralization rates were positively correlated (P < 0.05) with streamwater NO3/- concentrations. Forest floor NO3/- pools beneath alder [Alnus rugosa (Du Roi) Spreng] were positively correlated (P < 0.01) to streamwater NO3/- output. At the watershed mouth, streamwater NO3/- concentrations were positively correlated (P < 0.05) with precipitation NO3/- input and precipitation amount. The relatively small snowpack N content and seasonal precipitation N input compared to forest floor inorganic N pools and net N mineralization rates, the strong ecosystem retention of precipitation N inputs, and the seasonal streamwater NO3/- concentration and output pattern all indicated that little streamwater NO3/- came directly from precipitation or snowmelt.The Upper Great Lakes receive large amounts of precipitation-NH4+ and moderate NO3- inputs. Increased atmospheric inorganic N input has led to concern about ecosystem capacity to utilize excess N. This paper summarizes a 5-yr study of seasonal N content and flux in precipitation, snowpack, forest floor, and streamwater in order to assess the source of inorganic N outputs in streamflow from a small boreal watershed. Average precipitation N input was 3 kg ha-1 yr-1. The peak snowpack N content averaged 0.55 kg ha-1. The forest floor inorganic N pool was ??? 2 kg ha-1, eight times larger than monthly precipitation N input. The inorganic N pool size peaked in spring and early summer. Ninety percent of the forest floor inorganic N pool was made up of NH4+-N. Forest floor inorganic N pools generally increased with temperature. Net N mineralization was 15 kg ha-1 yr-1, and monthly rates peaked in early summer. During winter, the mean monthly net N mineralization rate was twice the peak snowpack N content. Streamwater NO3- concentration peaked in winter, and inorganic N output peaked in late fall. Beneath the dominant boreal forest species, net N mineralization rates were positively correlated (P < 0.05) with streamwater NO3- concentrations. Forest floor NO3- pools beneath alder [Alnus rugosa (Du Roi) Spreng] were positively correlated (P<0.01) to streamwater NO3- output. At the watershed mouth, streamwater NO3- concentrations were positively correlated (P < 0.05) with precipitation NO3- input and precipitation amount. The relatively small snowpack N content and seasonal precipitation N input compared to forest floor inorganic N pools and net N mineralization rates, the strong ecosystem retention of precipitation N inputs, and the seasonal streamwater NO3- concentration and output pattern all indicated that little streamwater NO3- came directly from precipitation or snowmelt.

Fifteen-year patterns of soil carbon and nitrogen following biomass harvesting

USGS Publications Warehouse

Kurth, Valerie J.; D'Amato, Anthony W.; Palik, Brian J.; Bradford, John B.

2014-01-01

The substitution of forest-derived woody biofuels for fossil fuel energy has garnered increasing attention in recent years, but information regarding the mid- and long-term effects on soil productivity is limited. We investigated 15-yr temporal trends in forest floor and mineral soil (0–30 cm) C and N pools in response to organic matter removal treatments (OMR; stem-only harvest, SOH; whole-tree harvest, WTH; and whole-tree plus forest floor removal, FFR) at three edaphically distinct aspen (Populus tremuloides Michx. and P. grandidentata Michx.) forests in the Great Lakes region. The OMR and temporal effects were generally site specific, and both were most evident in the forest floor and combined profile (mineral soil and forest floor) compared with the mineral soil alone. Forest floor and combined profile C and N pools were generally similar in the SOH and WTH treatments, suggesting that slash retention has little impact on soil C and N in this time frame. Temporal changes in C and N at one of the three sites were consistent with patterns documented following exotic earthworm invasion, but mineral soil pools at the other two sites were stable over time. Power analyses demonstrated that significant effects were more likely to be detected for temporal differences than the effects of OMR and in the combined profile than in the mineral soil. Our findings are consistent with previous work demonstrating that OMR effects on soil C and N pools are site specific and more apparent in the forest floor than the mineral soil.

Soil organic matter composition and quality across fire severity gradients in coniferous and deciduous forests of the southern boreal region

NASA Astrophysics Data System (ADS)

Miesel, Jessica R.; Hockaday, William C.; Kolka, Randall K.; Townsend, Philip A.

2015-06-01

Recent patterns of prolonged regional drought in southern boreal forests of the Great Lakes region, USA, suggest that the ecological effects of disturbance by wildfire may become increasingly severe. Losses of forest soil organic matter (SOM) during fire can limit soil nutrient availability and forest regeneration. These processes are also influenced by the composition of postfire SOM. We sampled the forest floor layer (i.e., full organic horizon) and 0-10 cm mineral soil from stands dominated by coniferous (Pinus banksiana Lamb.) or deciduous (Populus tremuloides Michx.) species 1-2 months after the 2011 Pagami Creek wildfire in northern Minnesota. We used solid-state 13C NMR to characterize SOM composition across a gradient of fire severity in both forest cover types. SOM composition was affected by fire, even when no statistically significant losses of total C stocks were evident. The most pronounced differences in SOM composition between burned and unburned reference areas occurred in the forest floor for both cover types. Carbohydrate stocks in forest floor and mineral horizons decreased with severity level in both cover types, whereas pyrogenic C stocks increased with severity in the coniferous forest floor and decreased in only the highest severity level in the deciduous forest floor. Loss of carbohydrate and lignin pools contributed to a decreased SOM stability index and increased decomposition index. Our results suggest that increases in fire severity expected to occur under future climate scenarios may lead to changes in SOM composition and dynamics with consequences for postfire forest recovery and C uptake.

Longer-term effects of selective thinning on microarthropod communities in a late-successional coniferous forest.

Treesearch

Robert W. Peck; Christine G. Niwa

2005-01-01

Microarthropod densities within late-successional coniferous forests thinned 16-41 yr before sampling were compared with adjacent unthinned stands to identify longer term effects of thinning on this community. Soil and forest floor layers were sampled separately on eight paired sites. Within the forest floor oribatid, mesostigmatid, and to a marginal extent,...

Contrasting responses to drought of forest floor CO2 efflux in a loblolly pine plantation and a nearby Oak-Hickory forest

Treesearch

S. Palmroth; Chris A. Maier; Heather R. McCarthy; A. C. Oishi; H. S. Kim; Kurt H. Johnsen; Gabrial G. Katul; Ram Oren

2005-01-01

Forest floor C02 efflux (Fff) depends on vegetation type, climate, and soil physical properties. We assessed the effects of biological factors on Fff by comparing a maturing pine plantation (PP) and a nearby mature Oak-Hickory-type hardwood forest (HW). Fff was measured...

Changes in necromass and nutrients on the forest floor of a palm floodplain forest in the Luquillo mountains of Puerto Rico.

Treesearch

ARIEL E. LUGO; JORGE L. FRANGI

2003-01-01

We studied changes that occurred between 1980 and 2000 in forest floor biomass (necromass+ biomass of herbaceous plants), nutrient stocks, and plant composition of a Prestoea montana floodplain forest. The forest was located in the Luquillo Mountains of Puerto Rico. Several storms and hurricanes passed near the study site during that period, the most severe being...

Sphagnum mosses limit total carbon consumption during fire in Alaskan black spruce forests

Treesearch

G. Shetler; .R. Turetsky; E. Kane; E. Kasischke

2008-01-01

The high water retention of hummock-forming Sphagnum species minimizes soil moisture fluctuations and might protect forest floor organic matter from burning during wildfire. We hypothesized that Sphagnum cover reduces overall forest floor organic matter consumption during wildfire compared with other ground-layer vegetation. We...

Transforming Pinus pinaster forest to recreation site: preliminary effects on LAI, some forest floor, and soil properties.

PubMed

Öztürk, Melih; Bolat, İlyas

2014-04-01

This study investigates the effects of forest transformation into recreation site. A fragment of a Pinus pinaster plantation forest was transferred to a recreation site in the city of Bartın located close to the Black Sea coast of northwestern Turkey. During the transformation, some of the trees were selectively removed from the forest to generate more open spaces for the recreationists. As a result, Leaf Area Index (LAI) decreased by 0.20 (about 11%). Additionally, roads and pathways were introduced into the site together with some recreational equipment sealing parts of the soil surface. Consequently, forest environment was altered with a semi-natural landscape within the recreation site. The purpose of this study is to assess the effects of forest transformation into recreation site particularly in terms of the LAI parameter, forest floor, and soil properties. Preliminary monitoring results indicate that forest floor biomass is reduced by 26% in the recreation site compared to the control site. Soil temperature is increased by 15% in the recreation site where selective removal of trees expanded the gaps allowing more light transmission. On the other hand, the soil bulk density which is an indicator of soil compaction is unexpectedly slightly lower in the recreation site. Organic carbon (C(org)) and total nitrogen (N(total)) together with the other physical and chemical parameter values indicate that forest floor and soil have not been exposed to much disturbance. However, subsequent removal of trees that would threaten the vegetation, forest floor, and soil should not be allowed. The activities of the recreationists are to be concentrated on the paved spaces rather than soil surfaces. Furthermore, long-term monitoring and management is necessary for both the observation and conservation of the site.

Effects of forest conversion on soil microbial communities depend on soil layer on the eastern Tibetan Plateau of China.

PubMed

He, Ruoyang; Yang, Kaijun; Li, Zhijie; Schädler, Martin; Yang, Wanqin; Wu, Fuzhong; Tan, Bo; Zhang, Li; Xu, Zhenfeng

2017-01-01

Forest land-use changes have long been suggested to profoundly affect soil microbial communities. However, how forest type conversion influences soil microbial properties remains unclear in Tibetan boreal forests. The aim of this study was to explore variations of soil microbial profiles in the surface organic layer and subsurface mineral soil among three contrasting forests (natural coniferous forest, NF; secondary birch forest, SF and spruce plantation, PT). Soil microbial biomass, activity and community structure of the two layers were investigated by chloroform fumigation, substrate respiration and phospholipid fatty acid analysis (PLFA), respectively. In the organic layer, both NF and SF exhibited higher soil nutrient levels (carbon, nitrogen and phosphorus), microbial biomass carbon and nitrogen, microbial respiration, PLFA contents as compared to PT. However, the measured parameters in the mineral soils often did not differ following forest type conversion. Irrespective of forest types, the microbial indexes generally were greater in the organic layer than in the mineral soil. PLFAs biomarkers were significantly correlated with soil substrate pools. Taken together, forest land-use change remarkably altered microbial community in the organic layer but often did not affect them in the mineral soil. The microbial responses to forest land-use change depend on soil layer, with organic horizons being more sensitive to forest conversion.

Establishment of ectomycorrhizal fungal community on isolated Nothofagus cunninghamii seedlings regenerating on dead wood in Australian wet temperate forests: does fruit-body type matter?

PubMed

Tedersoo, Leho; Gates, Genevieve; Dunk, Chris W; Lebel, Teresa; May, Tom W; Kõljalg, Urmas; Jairus, Teele

2009-08-01

Decaying wood provides an important habitat for animals and forms a seed bed for many shade-intolerant, small-seeded plants, particularly Nothofagus. Using morphotyping and rDNA sequence analysis, we compared the ectomycorrhizal fungal community of isolated N. cunninghamii seedlings regenerating in decayed wood against that of mature tree roots in the forest floor soil. The /cortinarius, /russula-lactarius, and /laccaria were the most species-rich and abundant lineages in forest floor soil in Australian sites at Yarra, Victoria and Warra, Tasmania. On root tips of seedlings in dead wood, a subset of the forest floor taxa were prevalent among them species of /laccaria, /tomentella-thelephora, and /descolea, but other forest floor dominants were rare. Statistical analyses suggested that the fungal community differs between forest floor soil and dead wood at the level of both species and phylogenetic lineage. The fungal species colonizing isolated seedlings on decayed wood in austral forests were taxonomically dissimilar to the species dominating in similar habitats in Europe. We conclude that formation of a resupinate fruit body type on the underside of decayed wood is not necessarily related to preferential root colonization in decayed wood. Rather, biogeographic factors as well as differential dispersal and competitive abilities of fungal taxa are likely to play a key role in structuring the ectomycorrhizal fungal community on isolated seedlings in decaying wood.

Upland log volumes and conifer establishment patterns in two northern, upland old-growth redwood forests, a brief synopsis

Treesearch

Daniel J. Porter; John O. Sawyer

2007-01-01

We characterized the volume, weight and top surface area of naturally fallen logs in an old-growth redwood forest, and quantified conifer recruit densities on these logs and on the surrounding forest floor. We report significantly greater conifer recruit densities on log substrates as compared to the forest floor. Log substrate availability was calculated on a per...

Chemical properties of litter inputs and organic matter along the Canadian Boreal Forest Transect Case Study

NASA Astrophysics Data System (ADS)

Preston, C. M.; Bhatti, J. S.; Norris, C. E.; Quideau, S. A.; Arevalo, C.

2012-04-01

To improve prediction of climate change impacts on the carbon balance of boreal forests, we are investigating C stocks, fluxes and organic matter quality of jack pine (Pinus banksiana) and black spruce (Picea mariana) stands in northern Saskatchewan and Manitoba along the Boreal Forest Transect Case Study (BFTCS). Jack pine stands occupy well-drained sandy soils with thin forest floor, whereas poorly-drained black spruce stands have a thick moss-dominated forest floor. Carbon storage for jack pine and black spruce stands respectively was 3.0-5.5 kg m-2 and 5.2-8.2 kg m-2 in vegetation, and 0.20-0.85 kg m-2 and 0.12-0.40 kg m-2 in coarse woody debris. Forest floor C stock was much higher for black spruce (6.0-12.7 kg m-2) than for jack pine (0.6-0.82 kg m-2). Mineral soil C to 50 cm was also significantly higher for black spruce (3.3-12.5 kg m-2) than for jack pine sites (2.2-3.0 kg m-2). Black spruce forest floor properties indicate hindered decomposition and N cycling, with high C/N ratios, strongly stratified and depleted ^13C and ^15N values, high tannins and phenolics, and 13C nuclear magnetic resonance (NMR) spectra typical of poorly decomposed plant material, especially roots and mosses. The thinner jack pine forest floor appears to be dominated by lichen, with charcoal in some samples. These contrasts are unlikely due to the small differences in aboveground litter inputs (110 vs 121 g m-2) for jack pine and black spruce respectively, 2000-2010 means) or litter quality. Development of colder, wetter and thicker black spruce forest floor is more likely associated with soil texture and drainage, further exacerbated by increasing sphagnum coverage and forest floor depth. This suggests that small environmental changes could trigger large C losses through enhanced forest floor decomposition. An investigation of mineral soil C stabilization in four jack pine sites showed that silt plus clay accounted for 15-43 % of 0-1 m C (1.5-2.8 kg m-2); silt held 0.9-3.3% of horizon mass and 13-31% of total C. Carbon-13 NMR of HF-treated silt fractions showed that alkyl and O-alkyl C dominated the A and B horizons, but C-horizon samples were higher in aromatic C, possibly of fire origin. HCl hydrolysis was used to to isolate older C, but most 14C dates were modern, with five samples from deeper horizons ranging from 141-5184 ybp. HCl residues were mainly alkyl and aromatic C. Especially for black spruce stands, soil C appears to be dominated by inputs from roots and moss, and stabilized mainly by environmental factors; soil C stored as thick forest floor is also vulnerable to loss by fire. Forest floor and mineral soil show evidence of pyrogenic C, but quantitative data are lacking to assess its role in long-term C sequestration. Considering the sensitivity of this region to climate change, further research should focus on understanding the processes controlling climate, vegetation and soil interactions throughout the lifecycle of jack pine and black spruce forests.

An increase in precipitation exacerbates negative effects of nitrogen deposition on soil cations and soil microbial communities in a temperate forest.

PubMed

Shi, Leilei; Zhang, Hongzhi; Liu, Tao; Mao, Peng; Zhang, Weixin; Shao, Yuanhu; Fu, Shenglei

2018-04-01

World soils are subjected to a number of anthropogenic global change factors. Although many previous studies contributed to understand how single global change factors affect soil properties, there have been few studies aimed at understanding how two naturally co-occurring global change drivers, nitrogen (N) deposition and increased precipitation, affect critical soil properties. In addition, most atmospheric N deposition and precipitation increase studies have been simulated by directly adding N solution or water to the forest floor, and thus largely neglect some key canopy processes in natural conditions. These previous studies, therefore, may not realistically simulate natural atmospheric N deposition and precipitation increase in forest ecosystems. In a field experiment, we used novel canopy applications to investigate the effects of N deposition, increased precipitation, and their combination on soil chemical properties and the microbial community in a temperate deciduous forest. We found that both soil chemistry and microorganisms were sensitive to these global change factors, especially when they were simultaneously applied. These effects were evident within 2 years of treatment initiation. Canopy N deposition immediately accelerated soil acidification, base cation depletion, and toxic metal accumulation. Although increased precipitation only promoted base cation leaching, this exacerbated the effects of N deposition. Increased precipitation decreased soil fungal biomass, possible due to wetting/re-drying stress or to the depletion of Na. When N deposition and increased precipitation occurred together, soil gram-negative bacteria decreased significantly, and the community structure of soil bacteria was altered. The reduction of gram-negative bacterial biomass was closely linked to the accumulation of the toxic metals Al and Fe. These results suggested that short-term responses in soil cations following N deposition and increased precipitation could change microbial biomass and community structure. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of forest conversion on soil microbial communities depend on soil layer on the eastern Tibetan Plateau of China

PubMed Central

He, Ruoyang; Yang, Kaijun; Li, Zhijie; Schädler, Martin; Yang, Wanqin; Wu, Fuzhong; Tan, Bo; Zhang, Li

2017-01-01

Forest land-use changes have long been suggested to profoundly affect soil microbial communities. However, how forest type conversion influences soil microbial properties remains unclear in Tibetan boreal forests. The aim of this study was to explore variations of soil microbial profiles in the surface organic layer and subsurface mineral soil among three contrasting forests (natural coniferous forest, NF; secondary birch forest, SF and spruce plantation, PT). Soil microbial biomass, activity and community structure of the two layers were investigated by chloroform fumigation, substrate respiration and phospholipid fatty acid analysis (PLFA), respectively. In the organic layer, both NF and SF exhibited higher soil nutrient levels (carbon, nitrogen and phosphorus), microbial biomass carbon and nitrogen, microbial respiration, PLFA contents as compared to PT. However, the measured parameters in the mineral soils often did not differ following forest type conversion. Irrespective of forest types, the microbial indexes generally were greater in the organic layer than in the mineral soil. PLFAs biomarkers were significantly correlated with soil substrate pools. Taken together, forest land-use change remarkably altered microbial community in the organic layer but often did not affect them in the mineral soil. The microbial responses to forest land-use change depend on soil layer, with organic horizons being more sensitive to forest conversion. PMID:28982191

Forest floor methane flux modelled by soil water content and ground vegetation - comparison to above canopy flux

NASA Astrophysics Data System (ADS)

Halmeenmäki, Elisa; Peltola, Olli; Haikarainen, Iikka; Ryhti, Kira; Rannik, Üllar; Pihlatie, Mari

2017-04-01

Methane (CH4) is an important and strong greenhouse gas of which atmospheric concentration is rising. While boreal forests are considered as an important sink of CH4 due to soil CH4 oxidation, the soils have also a capacity to emit CH4. Moreover, vegetation is shown to contribute to the ecosystem-atmosphere CH4 flux, and it has been estimated to be the least well known natural sources of CH4. In addition to well-known CH4 emissions from wetland plants, even boreal trees have been discovered to emit CH4. At the SMEAR (Station for Measuring Ecosystem-Atmosphere Relations) II station in Hyytiälä, southern Finland (61° 51' N, 24°17' E; 181 m asl), we have detected small CH4 emissions from above the canopy of a Scots pine (Pinus sylvestris) dominated forest. To assess the origin of the observed emissions, we conducted forest floor CH4 flux measurements with 54 soil chambers at the footprint area of the above canopy flux measurements during two growing seasons. In addition, we measured the soil volumetric water content (VWC) every time next to the forest floor chamber measurements, and estimated vegetation coverages inside the chambers. In order to model the forest floor CH4 flux at the whole footprint area, we combined lidar (light detection and ranging) data with the field measurements. To predict the soil water content and thus the potential CH4 flux, we used local elevation, slope, and ground return intensity (GRI), calculated from the lidar data (National Land Survey of Finland). We categorized the soil chambers into four classes based on the VWC so that the class with the highest VWC values includes all the soil chambers with a potential to emit CH4. Based on a statistically significant correlation between the VWC and the forest floor CH4 flux (r = 0.30, p < 0.001), we modelled the potential forest floor CH4 flux of the whole area. The results of the soil chamber measurements show a few areas of the forest floor with significant CH4 emissions. The modelled map of the potential CH4 flux is consistent with the measurements of the flux and the VWC, indicating that the wetter areas have potential for CH4 emissions, while the drier areas have potential for CH4 uptake. Preliminary results of the vegetation coverage show a positive correlation between the first year forest floor CH4 flux and the coverage of Sphagnum spp. mosses (r = 0.55, p < 0.001). Furthermore, we will include the vegetation coverage to the analysis, and compare the modelled forest floor CH4 flux with the measured above canopy flux. This ongoing research will give valuable information about the CH4 sources and dynamics in boreal forests.

Short-term recovery of NH4-15N applied to a temperate forest inceptisol and ultisol in east Tennessee USA

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

Garten Jr, Charles T; Brice, Deanne Jane; Todd Jr, Donald E

2007-11-01

The short-term fate and retention of ammonium (NH4)-{sup 15}nitrogen (N) applied to two types of forest soils in east Tennessee was investigated. Four ridgetop forests, predominantly oak (Quercus spp.), were studied. Five applications of NH{sub 4}-{sup 15}N tracer were made to the forest floor at 2- to 4-week intervals over a 14-week period in 2004. Nitrogen-15 recovery in the forest floor, fine roots (<2 mm), and the mineral soil (0-20 cm) was calculated at 6, 21, and 42 weeks after the last application. Most of the {sup 15}N was retained in the forest floor and the mineral soil, with onlymore » small amounts ({approx}<2%) found in roots from both soil layers. Recovery of NH{sub 4}-{sup 15}N was greater in Inceptisols, which had a wider carbon (C)-to-N ratio than Ultisols. For both soil types, higher NH{sub 4}-{sup 15}N recoveries and long retention times (half-lives>100 weeks) indicated the forest floor is an effective filter for atmospheric N inputs.« less

Changes in canopy cover alter surface air and forest floor temperature in a high-elevation red spruce (Picea rubens Sarg.) forest

Treesearch

Johnny L. Boggs; Steven G. McNulty

2010-01-01

The objective of this study is to describe winter and summer surface air and forest floor temperature patterns and diurnal fluctuations in high-elevation red spruce (Picea rubens Sarg.) forests with different levels of canopy cover. In 1988, a series of 10- x 10-meter plots (control, low nitrogen [N] addition, and high nitrogen addition) were...

Impacts of invasive earthworms on soil mercury cycling: Two mass balance approaches to an earthworm invasion in a northern Minnesota forest

Treesearch

Sona Psarska; Edward A. Nater; Randy Kolka

2016-01-01

Invasive earthworms perturb natural forest ecosystems that initially developed without them, mainly by consuming the forest floor (an organic rich surficial soil horizon) and by mixing the upper parts of the soil. The fate of mercury (Hg) formerly contained in the forest floor is largely unknown. We used two mass balance approaches (simple mass balance and geochemical...

Microhabitat effects of litter temperature and moisture on forest-floor invertebrate communities

Treesearch

Tim A. Christiansen; Sue A. Perry; William B. Perry

1996-01-01

Litter temperature and moisture may be altered due to changes in global climate. We investigated the effect of small changes in litter temperature and moisture on forest-floor communities in West Virginia.

Soil moisture sensitivity of autotrophic and heterotrophic forest floor respiration in boreal xeric pine and mesic spruce forests

NASA Astrophysics Data System (ADS)

Ťupek, Boris; Launiainen, Samuli; Peltoniemi, Mikko; Heikkinen, Jukka; Lehtonen, Aleksi

2016-04-01

Litter decomposition rates of the most process based soil carbon models affected by environmental conditions are linked with soil heterotrophic CO2 emissions and serve for estimating soil carbon sequestration; thus due to the mass balance equation the variation in measured litter inputs and measured heterotrophic soil CO2 effluxes should indicate soil carbon stock changes, needed by soil carbon management for mitigation of anthropogenic CO2 emissions, if sensitivity functions of the applied model suit to the environmental conditions e.g. soil temperature and moisture. We evaluated the response forms of autotrophic and heterotrophic forest floor respiration to soil temperature and moisture in four boreal forest sites of the International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) by a soil trenching experiment during year 2015 in southern Finland. As expected both autotrophic and heterotrophic forest floor respiration components were primarily controlled by soil temperature and exponential regression models generally explained more than 90% of the variance. Soil moisture regression models on average explained less than 10% of the variance and the response forms varied between Gaussian for the autotrophic forest floor respiration component and linear for the heterotrophic forest floor respiration component. Although the percentage of explained variance of soil heterotrophic respiration by the soil moisture was small, the observed reduction of CO2 emissions with higher moisture levels suggested that soil moisture response of soil carbon models not accounting for the reduction due to excessive moisture should be re-evaluated in order to estimate right levels of soil carbon stock changes. Our further study will include evaluation of process based soil carbon models by the annual heterotrophic respiration and soil carbon stocks.

7. Photo copy of blue print, (original in Forest Service ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. Photo copy of blue print, (original in Forest Service Office, Elkins, WV), November 1933. FIRST FLOOR PLAN, SECOND FLOOR PLAN. - Parsons Nursery, Manager's Residence, South side of U.S. Route 219, Parsons, Tucker County, WV

Wildfire and forest disease interaction lead to greater loss of soil nutrients and carbon.

PubMed

Cobb, Richard C; Meentemeyer, Ross K; Rizzo, David M

2016-09-01

Fire and forest disease have significant ecological impacts, but the interactions of these two disturbances are rarely studied. We measured soil C, N, Ca, P, and pH in forests of the Big Sur region of California impacted by the exotic pathogen Phytophthora ramorum, cause of sudden oak death, and the 2008 Basin wildfire complex. In Big Sur, overstory tree mortality following P. ramorum invasion has been extensive in redwood and mixed evergreen forests, where the pathogen kills true oaks and tanoak (Notholithocarpus densiflorus). Sampling was conducted across a full-factorial combination of disease/no disease and burned/unburned conditions in both forest types. Forest floor organic matter and associated nutrients were greater in unburned redwood compared to unburned mixed evergreen forests. Post-fire element pools were similar between forest types, but lower in burned-invaded compared to burned-uninvaded plots. We found evidence disease-generated fuels led to increased loss of forest floor C, N, Ca, and P. The same effects were associated with lower %C and higher PO4-P in the mineral soil. Fire-disease interactions were linear functions of pre-fire host mortality which was similar between the forest types. Our analysis suggests that these effects increased forest floor C loss by as much as 24.4 and 21.3 % in redwood and mixed evergreen forests, respectively, with similar maximum losses for the other forest floor elements. Accumulation of sudden oak death generated fuels has potential to increase fire-related loss of soil nutrients at the region-scale of this disease and similar patterns are likely in other forests, where fire and disease overlap.

Patterns of biomass and carbon distribution across a chronosequence of Chinese pine (Pinus tabulaeformis) forests.

PubMed

Zhao, Jinlong; Kang, Fengfeng; Wang, Luoxin; Yu, Xiaowen; Zhao, Weihong; Song, Xiaoshuai; Zhang, Yanlei; Chen, Feng; Sun, Yu; He, Tengfei; Han, Hairong

2014-01-01

Patterns of biomass and carbon (C) storage distribution across Chinese pine (Pinus tabulaeformis) natural secondary forests are poorly documented. The objectives of this study were to examine the biomass and C pools of the major ecosystem components in a replicated age sequence of P. tabulaeformis secondary forest stands in Northern China. Within each stand, biomass of above- and belowground tree, understory (shrub and herb), and forest floor were determined from plot-level investigation and destructive sampling. Allometric equations using the diameter at breast height (DBH) were developed to quantify plant biomass. C stocks in the tree and understory biomass, forest floor, and mineral soil (0-100 cm) were estimated by analyzing the C concentration of each component. The results showed that the tree biomass of P. tabulaeformis stands was ranged from 123.8 Mg·ha-1 for the young stand to 344.8 Mg·ha-1 for the mature stand. The understory biomass ranged from 1.8 Mg·ha-1 in the middle-aged stand to 3.5 Mg·ha-1 in the young stand. Forest floor biomass increased steady with stand age, ranging from 14.9 to 23.0 Mg·ha-1. The highest mean C concentration across the chronosequence was found in tree branch while the lowest mean C concentration was found in forest floor. The observed C stock of the aboveground tree, shrub, forest floor, and mineral soil increased with increasing stand age, whereas the herb C stock showed a decreasing trend with a sigmoid pattern. The C stock of forest ecosystem in young, middle-aged, immature, and mature stands were 178.1, 236.3, 297.7, and 359.8 Mg C ha-1, respectively, greater than those under similar aged P. tabulaeformis forests in China. These results are likely to be integrated into further forest management plans and generalized in other contexts to evaluate C stocks at the regional scale.

Patterns of Biomass and Carbon Distribution across a Chronosequence of Chinese Pine (Pinus tabulaeformis) Forests

PubMed Central

Wang, Luoxin; Yu, Xiaowen; Zhao, Weihong; Song, Xiaoshuai; Zhang, Yanlei; Chen, Feng; Sun, Yu; He, Tengfei; Han, Hairong

2014-01-01

Patterns of biomass and carbon (C) storage distribution across Chinese pine (Pinus tabulaeformis) natural secondary forests are poorly documented. The objectives of this study were to examine the biomass and C pools of the major ecosystem components in a replicated age sequence of P. tabulaeformis secondary forest stands in Northern China. Within each stand, biomass of above- and belowground tree, understory (shrub and herb), and forest floor were determined from plot-level investigation and destructive sampling. Allometric equations using the diameter at breast height (DBH) were developed to quantify plant biomass. C stocks in the tree and understory biomass, forest floor, and mineral soil (0–100 cm) were estimated by analyzing the C concentration of each component. The results showed that the tree biomass of P. tabulaeformis stands was ranged from 123.8 Mg·ha–1 for the young stand to 344.8 Mg·ha–1 for the mature stand. The understory biomass ranged from 1.8 Mg·ha–1 in the middle-aged stand to 3.5 Mg·ha–1 in the young stand. Forest floor biomass increased steady with stand age, ranging from 14.9 to 23.0 Mg·ha–1. The highest mean C concentration across the chronosequence was found in tree branch while the lowest mean C concentration was found in forest floor. The observed C stock of the aboveground tree, shrub, forest floor, and mineral soil increased with increasing stand age, whereas the herb C stock showed a decreasing trend with a sigmoid pattern. The C stock of forest ecosystem in young, middle-aged, immature, and mature stands were 178.1, 236.3, 297.7, and 359.8 Mg C ha–1, respectively, greater than those under similar aged P. tabulaeformis forests in China. These results are likely to be integrated into further forest management plans and generalized in other contexts to evaluate C stocks at the regional scale. PMID:24736660

Reduction of forest floor respiration by fertilization on both carbon dioxide-enriched and reference 17-year-old loblolly pine stands

Treesearch

John R. Butnor; Kurt H. Johnsen; Ram Oren; Gabriel G. Katul

2003-01-01

Elevated atmospheric carbon dioxide (CO2e) increases soil respiration rates in forest, grassland, agricultural and wetland systems as a result of increased growth, root biomass and enhanced biological activity of soil microorganisms. Less is known about how forest floor fluxes respond to the combined effects of elevated CO...

Singular and combined effects of blowdown, salvage logging, and wildfire on forest floor and soil mercury pools

Treesearch

Carl P.J. Mitchell; Randall K. Kolka; Shawn Fraver

2012-01-01

A number of factors influence the amount of mercury (Hg) in forest floors and soils, including deposition, volatile emission, leaching, and disturbances such as fire. Currently the impact on soil Hg pools from other widespread forest disturbances such as blowdown and management practices like salvage logging are unknown. Moreover, ecological and biogeochemical...

Abundance and distribution of vegetation under four hardwood stands in north-central West Virginia

Treesearch

G.W. Wendel; G.W. Wendel

1987-01-01

Forest floor samples were collected from four hardwood forest stands in West Virginia to study species composition, abundance, and distribution of vegetation that originated from seeds, rootstocks, rhizomes, and so on. The abundance and distribution of plants on square-foot sections of forest floor that were lifted and moved to the greenhouse indicate that under the...

An empirical assessment of forest floor carbon stock components across the United States

Treesearch

Christopher W. Woodall; Charles H. Perry; James A. Westfall

2012-01-01

Despite its prevalent reporting in regional/national greenhouse gas inventories (NGHGI), forest floor (FF) carbon (C) stocks (including litter, humus, and fine woody debris [FWD]) have not been empirically measured using a consistent approach across forests of the US. The goal of this study was to use the first national field inventory of litter and humic layer depths...

Fuel loadings in southwestern ecosystems of the United States

Treesearch

Stephen S. Sackett; Sally M Haase

1996-01-01

Natural forest fuel loadings cause extreme fire behavior during dry, windy weather experienced during most fire seasons in the Southwest. Fire severity is also exacerbated from burning heavy fuels, including heavy humus layers on the forest floor. Ponderosa pine and mixed conifer stands possess more than 21.7 and 44.1 tons per acre of total forest floor fuel,...

Aspen development on similar soils in Minnesota and British Columbia after compaction and forest floor removal

Treesearch

Douglas M. Stone; Richard Kabzems

2002-01-01

Forest management practices that decrease soil porosity and remove organic matter can reduce site productivity. We evaluated effects of four treatments-merchantable bole harvest (MBH) with three levels of soil compaction (none, light, or heavy), and total woody vegetation harvest plus forest floor removal (FFR)-on fifth-year regeneration and growth of aspen (...

Soil responses to management, increased precipitation, and added nitrogen in ponderosa pine forests.

PubMed

Hungate, Bruce A; Hart, Stephen C; Selmants, Paul C; Boyle, Sarah I; Gehring, Catherine A

2007-07-01

Forest management, climatic change, and atmospheric N deposition can affect soil biogeochemistry, but their combined effects are not well understood. We examined the effects of water and N amendments and forest thinning and burning on soil N pools and fluxes in ponderosa pine forests near Flagstaff, Arizona (USA). Using a 15N-depleted fertilizer, we also documented the distribution of added N into soil N pools. Because thinning and burning can increase soil water content and N availability, we hypothesized that these changes would alleviate water and N limitation of soil processes, causing smaller responses to added N and water in the restored stand. We found little support for this hypothesis. Responses of fine root biomass, potential net N mineralization, and the soil microbial N to water and N amendments were mostly unaffected by stand management. Most of the soil processes we examined were limited by N and water, and the increased N and soil water availability caused by forest restoration was insufficient to alleviate these limitations. For example, N addition caused a larger increase in potential net nitrification in the restored stand, and at a given level of soil N availability, N addition had a larger effect on soil microbial N in the restored stand. Possibly, forest restoration increased the availability of some other limiting resource, amplifying responses to added N and water. Tracer N recoveries in roots and in the forest floor were lower in the restored stand. Natural abundance delta15N of labile soil N pools were higher in the restored stand, consistent with a more open N cycle. We conclude that thinning and burning open up the N cycle, at least in the short-term, and that these changes are amplified by enhanced precipitation and N additions. Our results suggest that thinning and burning in ponderosa pine forests will not increase their resistance to changes in soil N dynamics resulting from increased atmospheric N deposition or increased precipitation due to climatic change. Restoration plans should consider the potential impact on long-term forest productivity of greater N losses from a more open N cycle, especially during the period immediately after thinning and burning.

Fire effects on temperate forest soil C and N storage.

PubMed

Nave, Lucas E; Vance, Eric D; Swanston, Christopher W; Curtis, Peter S

2011-06-01

Temperate forest soils store globally significant amounts of carbon (C) and nitrogen (N). Understanding how soil pools of these two elements change in response to disturbance and management is critical to maintaining ecosystem services such as forest productivity, greenhouse gas mitigation, and water resource protection. Fire is one of the principal disturbances acting on forest soil C and N storage and is also the subject of enormous management efforts. In the present article, we use meta-analysis to quantify fire effects on temperate forest soil C and N storage. Across a combined total of 468 soil C and N response ratios from 57 publications (concentrations and pool sizes), fire had significant overall effects on soil C (-26%) and soil N (-22%). The impacts of fire on forest floors were significantly different from its effects on mineral soils. Fires reduced forest floor C and N storage (pool sizes only) by an average of 59% and 50%, respectively, but the concentrations of these two elements did not change. Prescribed fires caused smaller reductions in forest floor C and N storage (-46% and -35%) than wildfires (-67% and -69%), and the presence of hardwoods also mitigated fire impacts. Burned forest floors recovered their C and N pools in an average of 128 and 103 years, respectively. Among mineral soils, there were no significant changes in C or N storage, but C and N concentrations declined significantly (-11% and -12%, respectively). Mineral soil C and N concentrations were significantly affected by fire type, with no change following prescribed burns, but significant reductions in response to wildfires. Geographic variation in fire effects on mineral soil C and N storage underscores the need for region-specific fire management plans, and the role of fire type in mediating C and N shifts (especially in the forest floor) indicates that averting wildfires through prescribed burning is desirable from a soils perspective.

Complementary models of tree species-soil relationships in old-growth temperate forests

USGS Publications Warehouse

Cross, Alison; Perakis, Steven S.

2011-01-01

Ecosystem level studies identify plant soil feed backs as important controls on soil nutrient availability,particularly for nitrogen and phosphorus. Although site and species specific studies of tree species soil relationships are relatively common,comparatively fewer studies consider multiple coexisting speciesin old-growth forests across a range of sites that vary underlying soil fertility. We characterized patterns in forest floor and mineral soil nutrients associated with four common tree species across eight undisturbed old-growth forests in Oregon, USA, and used two complementary conceptual models to assess tree species soil relationships. Plant soil feedbacks that could reinforce sitelevel differences in nutrient availability were assessed using the context dependent relationships model, where by relative species based differences in each soil nutrient divergedorconvergedas nutrient status changed across sites. Tree species soil relationships that did not reflect strong feedbacks were evaluated using a site independent relationships model, where by forest floor and surface mineral soil nutrient tools differed consistently by tree species across sites,without variation in deeper mineral soils. We found that theorganically cycled elements carbon, nitrogen, and phosphorus exhibited context-dependent differences among species in both forest floor and mineral soil, and most of ten followed adivergence model,where by species differences were greatest at high-nutrient sites. These patterns are consistent with the oryemphasizing biotic control of these elements through plant soil feedback mechanisms. Site independent species differences were strongest for pool so if the weather able cations calcium, magnesium, potassium,as well as phosphorus, in mineral soils. Site independent species differences in forest floor nutrients we reattributable too nespecies that displayed significant greater forest floor mass accumulation. Our finding confirmed that site-independent and context-dependent tree species-soil relationships occur simultaneouslyinold-grow the temperate forests, with context-dependent relationships strongest for organically cycled elements, and site-independent relationships strongest for weather able elements with in organic cycling phases. These models provide complementary explanations for patterns of nutrient accumulation and cycling in mixed species old-growth temperate forests.

A meta-analysis of soil microbial biomass responses to forest disturbances

PubMed Central

Holden, Sandra R.; Treseder, Kathleen K.

2013-01-01

Climate warming is likely to increase the frequency and severity of forest disturbances, with uncertain consequences for soil microbial communities and their contribution to ecosystem C dynamics. To address this uncertainty, we conducted a meta-analysis of 139 published soil microbial responses to forest disturbances. These disturbances included abiotic (fire, harvesting, storm) and biotic (insect, pathogen) disturbances. We hypothesized that soil microbial biomass would decline following forest disturbances, but that abiotic disturbances would elicit greater reductions in microbial biomass than biotic disturbances. In support of this hypothesis, across all published studies, disturbances reduced soil microbial biomass by an average of 29.4%. However, microbial responses differed between abiotic and biotic disturbances. Microbial responses were significantly negative following fires, harvest, and storms (48.7, 19.1, and 41.7% reductions in microbial biomass, respectively). In contrast, changes in soil microbial biomass following insect infestation and pathogen-induced tree mortality were non-significant, although biotic disturbances were poorly represented in the literature. When measured separately, fungal and bacterial responses to disturbances mirrored the response of the microbial community as a whole. Changes in microbial abundance following disturbance were significantly positively correlated with changes in microbial respiration. We propose that the differential effect of abiotic and biotic disturbances on microbial biomass may be attributable to differences in soil disruption and organic C removal from forests among disturbance types. Altogether, these results suggest that abiotic forest disturbances may significantly decrease soil microbial abundance, with corresponding consequences for microbial respiration. Further studies are needed on the effect of biotic disturbances on forest soil microbial communities and soil C dynamics. PMID:23801985

Uncoupling of microbial community structure and function in decomposing litter across beech forest ecosystems in Central Europe.

PubMed

Purahong, Witoon; Schloter, Michael; Pecyna, Marek J; Kapturska, Danuta; Däumlich, Veronika; Mital, Sanchit; Buscot, François; Hofrichter, Martin; Gutknecht, Jessica L M; Krüger, Dirk

2014-11-12

The widespread paradigm in ecology that community structure determines function has recently been challenged by the high complexity of microbial communities. Here, we investigate the patterns of and connections between microbial community structure and microbially-mediated ecological function across different forest management practices and temporal changes in leaf litter across beech forest ecosystems in Central Europe. Our results clearly indicate distinct pattern of microbial community structure in response to forest management and time. However, those patterns were not reflected when potential enzymatic activities of microbes were measured. We postulate that in our forest ecosystems, a disconnect between microbial community structure and function may be present due to differences between the drivers of microbial growth and those of microbial function.

[Vertical distribution of fuels in Pinus yunnanensis forest and related affecting factors].

PubMed

Wang, San; Niu, Shu-Kui; Li, De; Wang, Jing-Hua; Chen, Feng; Sun, Wu

2013-02-01

In order to understand the effects of fuel loadings spatial distribution on forest fire kinds and behaviors, the canopy fuels and floor fuels of Pinus yunnanensis forests with different canopy density, diameter at breast height (DBH), tree height, and stand age and at different altitude, slope grade, position, and aspect in Southwest China were taken as test objects, with the fuel loadings and their spatial distribution characteristics at different vertical layers compared and the fire behaviors in different stands analyzed. The relationships between the fuel loadings and the environmental factors were also analyzed by canonical correspondence analysis (CCA). In different stands, there existed significant differences in the vertical distribution of fuels. Pinus yunnanensis-Qak-Syzygium aromaticum, Pinus yunnanensis-oak, and Pinus yunnanensis forests were likely to occur floor fire but not crown fire, while Pinus yunnanensis-Platycladus orientalis, Pinus yunnanensis-Keteleeria fortune, and Keteleeria fortune-Pinus yunnanensis were not only inclined to occur floor fire, but also, the floor fire could be easily transformed into crown fire. The crown fuels were mainly affected by the stand age, altitude, DBH, and tree height, while the floor fuels were mainly by the canopy density, slope grade, altitude, and stand age.

Effect of species composition on carbon and nitrogen stocks in forest floor and mineral soil in Norway spruce and European beech mixed forests

NASA Astrophysics Data System (ADS)

Andivia, Enrique; Rolo, Víctor; Jonard, Mathieu; Formánek, Pavel; Ponette, Quentin

2015-04-01

Management of existing forests has been identified as the main strategy to enhance carbon sequestration and to mitigate the impact of climate change on forest ecosystems. In this direction, the conversion of Norway spruce monospecific stands into mixed stands by intermingling individuals of European beech is an ongoing trend in adaptive forest management strategies, especially in Central Europe. However, studies assessing the effect of changes in tree species composition on soil organic carbon (SOC) and nitrogen stocks are still scarce and there is a lack of scientific evidence supporting tree species selection as a feasible management option to mitigate the effects of predicted future climatic scenarios. We compared C and N stocks in the forest floor (litter and humus) and the top 10 cm of mineral soil in two monospecific stands of Norway spruce and European beech and in a mixed stand of both species. The effect of tree species composition on the C and N stocks and its spatial distribution was evaluated based on litterfall, root production, elevation and canopy opening, and by using a combination of modelling and geostatistical techniques. C stock was highest in the Norway spruce and the mixed stands, while N stock was highest in the mixed stand and lowest under European beech, with intermediate values in the Norway spruce stand. Each forest type showed differences in forest floor properties, suggesting that species composition is an important factor governing forest floor characteristics, including C and N stocks. The distribution of C and N stocks between forest soil layers was different for each forest type. C and N stocks were highest in the hummus layer under Norway spruce, whereas both stocks were lowest in the European beech stand. On the other hand, the mixed stand showed the highest C and N accumulation in the uppermost mineral soil layer, while the monospecific stands showed similar values. Litterfall was the main contribution to C and N stocks of the humus layer in monospecific stands. Forest floor stocks were also influenced by microelevation and canopy opening in the European beech stand and by microelevation in the Norway spruce stand. Root turnover and Norway spruce litterfall proportion directly increased C stocks in the mineral soil of the mixed stand. Additionally, N stock in the forest floor of the mixed stand was positively correlated with the Norway spruce litterfall proportion. Spatial analyses further confirmed that species composition was the main source of spatial variability of SOC stock in mixed stands. These results suggest that the admixture of individuals of European beech and Norway spruce may lead to a translocation of SOC from the forest floor to the better protected mineral soil layer, which might be beneficial for long term SOC sequestration.

36 CFR 910.60 - Gross floor area.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 3 2011-07-01 2011-07-01 false Gross floor area. 910.60 Section 910.60 Parks, Forests, and Public Property PENNSYLVANIA AVENUE DEVELOPMENT CORPORATION GENERAL GUIDELINES AND UNIFORM STANDARDS FOR URBAN PLANNING AND DESIGN OF DEVELOPMENT WITHIN THE PENNSYLVANIA AVENUE...

36 CFR 910.60 - Gross floor area.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Gross floor area. 910.60 Section 910.60 Parks, Forests, and Public Property PENNSYLVANIA AVENUE DEVELOPMENT CORPORATION GENERAL GUIDELINES AND UNIFORM STANDARDS FOR URBAN PLANNING AND DESIGN OF DEVELOPMENT WITHIN THE PENNSYLVANIA AVENUE...

Changes in forest floor and soil nutrients in a mixed oak forest 33 years after stem only and whole-tree harvest

Treesearch

D.W. Johnson; C.C. Trettin; D.E. Todd

2016-01-01

Vegetation, forest floor, and soils were resampled at a mixed oak site in eastern Tennessee that had been subjected to stem only (SOH), whole-tree harvest (WTH), and no harvest (REF) 33 years previously. Although differences between harvest treatments were not statistically significant (P < 0.05), average diameter, height, basal...

Chemical characteristics and acidity of soluble organic substances from a northern hardwood forest floor, central Maine, USA

NASA Astrophysics Data System (ADS)

Vance, George F.; David, Mark B.

1991-12-01

Our understanding of the chemistry, structure, and reactions of organic substances in forest floor leachates is limited and incomplete. Therefore, we examined the organic and inorganic chemistry of forest floor leachates collected from a hardwood forest in central Maine over a two-year period (1987-1989), including detailed study of dissolved organic carbon (DOC). Seasonal variations in NH 4+, NO 3-, K +, and total Al were believed due to organic matter decomposition and release. Leaching of other base cations closely followed that of NO 3-. Snowmelt resulted in NO 3- levels that decreased in time due to flushing of mineralization/nitrification by-products that had accumulated during the winter months. Total DOC ranged from 2228 to 7193 μmol L -1 with an average of 4835 μmol L -1. Monosaccharides and polyphenols constituted 3.9% (range of 3.4 to 4.4%) and 3.0% (2.2 to 3.7%) of the DOC, respectively, which suggests DOC may contain partially oxidized products that are possibly of a lignocellulose nature. Fractionation of the forest floor DOC indicated high organic acid contents (hydrophobic and hydrophilic acids) that averaged 92% of the total DOC. Organic acids were isolated and analyzed for elemental content (C, H, N, and S), and determination of UV absorptivity ( E 4/E 6) ratios, CuO oxidation products, FT-IR and 13C-NMR spectra, and acidity by potentiometric titration. Results from these analyses indicate the organic acids in the forest floor leachates are similar to fulvic acids. Hydrophobic and hydrophilic acids had average exchange acidities of 0.126 and 0.148 μeq μmol -1 C, respectively, and pKa, of 4.23 and 4.33. Their FT-IR and 13C-NMR spectra suggest they are primarily carboxylic acids, with aliphatic and aromatic structure. An organic charge contribution model was developed using titration data, DOC fractionation percentages, and the total DOC in the forest floor leachates. Application of the model to all solutions accounted for 97% of the charge balance deficits. Adjusted values for the flux of C and organic acidity due to organic solutes in forest floor leachates indicated translocation of 112 to 260 kg C ha -1 yr -1 and 460 to 1330 eq ha -1 yr -1, respectively, to the underlying mineral subsurface horizons.

Decreases in Soil Moisture and Organic Matter Quality Suppress Microbial Decomposition Following a Boreal Forest Fire

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

Holden, Sandra R.; Berhe, Asmeret A.; Treseder, Kathleen K.

Climate warming is projected to increase the frequency and severity of wildfires in boreal forests, and increased wildfire activity may alter the large soil carbon (C) stocks in boreal forests. Changes in boreal soil C stocks that result from increased wildfire activity will be regulated in part by the response of microbial decomposition to fire, but post-fire changes in microbial decomposition are poorly understood. Here, we investigate the response of microbial decomposition to a boreal forest fire in interior Alaska and test the mechanisms that control post-fire changes in microbial decomposition. We used a reciprocal transplant between a recently burnedmore » boreal forest stand and a late successional boreal forest stand to test how post-fire changes in abiotic conditions, soil organic matter (SOM) composition, and soil microbial communities influence microbial decomposition. We found that SOM decomposing at the burned site lost 30.9% less mass over two years than SOM decomposing at the unburned site, indicating that post-fire changes in abiotic conditions suppress microbial decomposition. Our results suggest that moisture availability is one abiotic factor that constrains microbial decomposition in recently burned forests. In addition, we observed that burned SOM decomposed more slowly than unburned SOM, but the exact nature of SOM changes in the recently burned stand are unclear. Finally, we found no evidence that post-fire changes in soil microbial community composition significantly affect decomposition. Taken together, our study has demonstrated that boreal forest fires can suppress microbial decomposition due to post-fire changes in abiotic factors and the composition of SOM. Models that predict the consequences of increased wildfires for C storage in boreal forests may increase their predictive power by incorporating the observed negative response of microbial decomposition to boreal wildfires.« less

Invasive and exotic earthworms: an unaccounted change to mercury cycling in northeastern US forest soils

NASA Astrophysics Data System (ADS)

Richardson, J. B.; Friedland, A. J.; Görres, J. H.; Renock, D. J.; Jackson, B. P.

2014-12-01

Invasive and exotic earthworms are now present in many forested areas of the northeastern US with currently unquantified consequences to abiotic and biotic Hg cycling. To quantify these effects, we measured Hg concentrations (mg kg-1) and amounts (μg m-2) in earthworms and soil horizons at 45 soil pits from 9 sites in northern New England. Seven earthworm species were observed in varying assemblages. Most earthworm species attained concentrations of Hg potentially hazardous to wildlife that may ingest them, with highest concentrations found in shallow-burrowing, litter-feeders. Specifically, Aporrectodea rosea and Amynthas agrestis had the greatest Hg concentrations (0.9 ± 0.1) and Hg amounts (8 ± 2) μg m-2. Aporrectodea rosea and Amynthas agrestis were found to inhabit the forest floor and the top 5 cm of the mineral horizons in high abundance, potentially making it a readily accessible prey species. Bioaccumulation of Hg by invasive and exotic earthworms may be an important mechanism that transfers Hg to ground foraging predators, such as thrushes, red-backed salamanders and foxes, which is generally unaccounted for in terrestrial food chains. Earthworm Hg concentrations were poorly correlated with their respective soil Hg concentrations, suggesting a species dependence for Hg bioaccumulation rather than site effects. We observed that forest floor Hg concentrations and amounts were 23% and 57% lower, respectively, at soil pits with earthworms compared to those without. Moreover, Hg amounts in forest floor-feeding earthworms exceeded the remaining forest floor Hg pools. Mercury concentrations and pools in the mineral soil were 21% and 33% lower, respectively, for soil pits with earthworms compared to those without. We hypothesize that enhanced decomposition, horizon disturbance and bioaccumulation by earthworms has decreased Hg amounts in the forest floor and mineral soil. Our results suggest that earthworms are decreasing Hg storage in forest soils with potential hazardous impacts for predatory animals in northeastern US forests and other ecosystems.

Nitrogen cycling in canopy soils of tropical montane forests responds rapidly to indirect N and P fertilization.

PubMed

Matson, Amanda L; Corre, Marife D; Veldkamp, Edzo

2014-12-01

Although the canopy can play an important role in forest nutrient cycles, canopy-based processes are often overlooked in studies on nutrient deposition. In areas of nitrogen (N) and phosphorus (P) deposition, canopy soils may retain a significant proportion of atmospheric inputs, and also receive indirect enrichment through root uptake followed by throughfall or recycling of plant litter in the canopy. We measured net and gross rates of N cycling in canopy soils of tropical montane forests along an elevation gradient and assessed indirect effects of elevated nutrient inputs to the forest floor. Net N cycling rates were measured using the buried bag method. Gross N cycling rates were measured using (15) N pool dilution techniques. Measurements took place in the field, in the wet and dry season, using intact cores of canopy soil from three elevations (1000, 2000 and 3000 m). The forest floor had been fertilized biannually with moderate amounts of N and P for 4 years; treatments included control, N, P, and N + P. In control plots, gross rates of NH4 (+) transformations decreased with increasing elevation; gross rates of NO3 (-) transformations did not exhibit a clear elevation trend, but were significantly affected by season. Nutrient-addition effects were different at each elevation, but combined N + P generally increased N cycling rates at all elevations. Results showed that canopy soils could be a significant N source for epiphytes as well as contributing up to 23% of total (canopy + forest floor) mineral N production in our forests. In contrast to theories that canopy soils are decoupled from nutrient cycling in forest floor soil, N cycling in our canopy soils was sensitive to slight changes in forest floor nutrient availability. Long-term atmospheric N and P deposition may lead to increased N cycling, but also increased mineral N losses from the canopy soil system. © 2014 John Wiley & Sons Ltd.

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.

78 FR 72914 - Changes in Flood Hazard Determinations

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-04

.... Forest Hill, Hill, TX 76119. 3219 California Parkway, Forest Hill, TX 76119. Travis City of Austin (13..., Austin, TX Road, 12th 78767. Floor, Austin, TX 78704. Travis Unincorporated The Honorable Travis County..., 700 Austin, TX 78767. Lavaca Street, 5th Floor, Suite 540, Austin, TX 78701. Williamson City of...

Forest floor and mineral soil respiration rates in a northern Minnesota red pine chronosequence

Treesearch

Matthew Powers; Randall Kolka; John Bradford; Brian Palik; Martin Jurgensen

2017-01-01

We measured total soil CO2 efflux (RS) and efflux from the forest floor layers (RFF) in red pine (Pinus resinosa Ait.) stands of different ages to examine relationships between stand age and belowground C cycling. Soil temperature and RS were often lower in...

Effect of radiocesium transfer on ambient dose rate in forest environments affected by the Fukushima Nuclear Power Plant accident

NASA Astrophysics Data System (ADS)

Kato, H.

2015-12-01

We investigated the transfer of canopy-intercepted radiocesium to the forest floor during 3 years following the Fukushima Daiichi Nuclear Power Plant accident. The cesium-137 (Cs-137) contents in throughfall, stemflow, and litterfall were monitored in two coniferous stands (plantation of Japanese cedar) and a deciduous broad-leaved forest stand (Japanese oak with red pine). We also measured the ambient dose rate (ADR) at different heights in the forest using a survey meter and a portable Ge gamma-ray detector. Total Cs-137 deposition flux from the canopy to forest floor for the mature cedar, young cedar, and the mixed broad-leaved stands were 166 kBq/m2, 174 kBq/m2, and 60 kBq/m2, respectively. These values correspond to 38%, 40% and 13% of total atmospheric input after the accident. The ambient dose rate in forest exhibited height dependency and its vertical distribution varied with forest type and stand age. The ambient dose rate showed an exponential decrease with time for all the forest sites, however the decreasing trend differed depending on the height of dose measurement and forest type. The ambient dose rate at the canopy (approx. 10 m-height) decreased faster than that expected from physical decay of the two radiocesium isotopes, whereas those at the forest floor varied between the three forest stands. The radiocesium deposition via throughfall seemed to increase ambient dose rate during the first 200 days after the accident, however there was no clear relationship between litterfall and ambient dose rate since 400 days after the accident. These data suggested that the ambient dose rate in forest environment varied both spatially and temporally reflecting the transfer of radiocesium from canopy to forest floor. However, further monitoring investigation and analysis are required to determine the effect of litterfall on long-term trend of ambient dose rate in forest environments.

Successional and seasonal variations in soil and litter microbial community structure and function during tropical postagricultural forest regeneration: a multiyear study.

PubMed

Smith, A Peyton; Marín-Spiotta, Erika; Balser, Teri

2015-09-01

Soil microorganisms regulate fundamental biochemical processes in plant litter decomposition and soil organic matter (SOM) transformations. Understanding how microbial communities respond to changes in vegetation is critical for improving predictions of how land-cover change affects belowground carbon storage and nutrient availability. We measured intra- and interannual variability in soil and forest litter microbial community composition and activity via phospholipid fatty acid analysis (PLFA) and extracellular enzyme activity across a well-replicated, long-term chronosequence of secondary forests growing on abandoned pastures in the wet subtropical forest life zone of Puerto Rico. Microbial community PLFA structure differed between young secondary forests and older secondary and primary forests, following successional shifts in tree species composition. These successional patterns held across seasons, but the microbial groups driving these patterns differed over time. Microbial community composition from the forest litter differed greatly from those in the soil, but did not show the same successional trends. Extracellular enzyme activity did not differ with forest succession, but varied by season with greater rates of potential activity in the dry seasons. We found few robust significant relationships among microbial community parameters and soil pH, moisture, carbon, and nitrogen concentrations. Observed inter- and intrannual variability in microbial community structure and activity reveal the importance of a multiple, temporal sampling strategy when investigating microbial community dynamics with land-use change. Successional control over microbial composition with forest recovery suggests strong links between above and belowground communities. © 2015 John Wiley & Sons Ltd.

Forensic analysis of the microbiome of phones and shoes

DOE PAGES

Lax, Simon; Hampton-Marcell, Jarrad T.; Gibbons, Sean M.; ...

2015-05-12

Background: Microbial interaction between human-associated objects and the environments we inhabit may have forensic implications, and the extent to which microbes are shared between individuals inhabiting the same space may be relevant to human health and disease transmission. In this study, two participants sampled the front and back of their cell phones, four different locations on the soles of their shoes, and the floor beneath them every waking hour over a 2-day period. A further 89 participants took individual samples of their shoes and phones at three different scientific conferences. Results: Samples taken from different surface types maintained significantly differentmore » microbial community structures. The impact of the floor microbial community on that of the shoe environments was strong and immediate, as evidenced by Procrustes analysis of shoe replicates and significant correlation between shoe and floor samples taken at the same time point. Supervised learning was highly effective at determining which participant had taken a given shoe or phone sample, and a Bayesian method was able to determine which participant had taken each shoe sample based entirely on its similarity to the floor samples. Both shoe and phone samples taken by conference participants clustered into distinct groups based on location, though much more so when an unweighted distance metric was used, suggesting sharing of low-abundance microbial taxa between individuals inhabiting the same space. In conclusion, correlations between microbial community sources and sinks allow for inference of the interactions between humans and their environment.« less

Forensic analysis of the microbiome of phones and shoes

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

Lax, Simon; Hampton-Marcell, Jarrad T.; Gibbons, Sean M.

Background: Microbial interaction between human-associated objects and the environments we inhabit may have forensic implications, and the extent to which microbes are shared between individuals inhabiting the same space may be relevant to human health and disease transmission. In this study, two participants sampled the front and back of their cell phones, four different locations on the soles of their shoes, and the floor beneath them every waking hour over a 2-day period. A further 89 participants took individual samples of their shoes and phones at three different scientific conferences. Results: Samples taken from different surface types maintained significantly differentmore » microbial community structures. The impact of the floor microbial community on that of the shoe environments was strong and immediate, as evidenced by Procrustes analysis of shoe replicates and significant correlation between shoe and floor samples taken at the same time point. Supervised learning was highly effective at determining which participant had taken a given shoe or phone sample, and a Bayesian method was able to determine which participant had taken each shoe sample based entirely on its similarity to the floor samples. Both shoe and phone samples taken by conference participants clustered into distinct groups based on location, though much more so when an unweighted distance metric was used, suggesting sharing of low-abundance microbial taxa between individuals inhabiting the same space. In conclusion, correlations between microbial community sources and sinks allow for inference of the interactions between humans and their environment.« less

A canopy trimming experiment in Puerto Rico: the response of litter invertebrate communities to canopy loss and debris deposition in a tropical forest subject to hurricanes

Treesearch

Barbara A. Richardson; Michael J. Richardson; Grizelle Gonzalez; Aaron B. Shiels; Diane S. Srivastava

2010-01-01

Hurricanes cause canopy removal and deposition of pulses of litter to the forest floor. A Canopy Trimming Experiment (CTE) was designed to decouple these two factors, and to investigate the separate abiotic and biotic consequences of hurricane-type damage and monitor recovery processes. As part of this experiment, effects on forest floor invertebrate communities were...

Rates of forest floor decomposition and nutrient turnover in aspen, pine, and spruce stands on two soils.

Treesearch

D. A. Perala; D.H. Alban

1982-01-01

Compares rates of forest floor decomposition and nutrient turnover in aspen and conifers. These rates were generally most rapid under aspen, slowest under spruce, and more rapid on a loamy fine sand than on a very fine sandy loam. Compares results with literature values.

Forest Floor CO2 Flux From Two Contrasting Ecosystems in the Southern Appalachians

Treesearch

James M. Vose; Barton D. Clinton; Verl Emrick

1995-01-01

We measured forest floor CO2 flux in two contrasting ecosystems (white pine plantation and northern hardwood ecosystems at low and high elevations, respectively) in May and September 1993 to quantify differences and determine factors regulating CO2 fluxes. An automated IRGA based, flow through system was used with chambers...

Impact of prescribed fire on understory and forest floor nutrients

Treesearch

Walter A. Hough

1981-01-01

The impact of low-intensity prescribed fires on slash pine/saw-palmetto/gallberry understory and forest floor nutrients was estimated from measurements before and after burning. Highly significant correlations existed between weight loss of these fuel components and the weight loss of several elements. Energy loss was also highly correlated with forestfloor and...

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 ...

36 CFR 1192.79 - Floors, steps and thresholds.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Floors, steps and thresholds... Light Rail Vehicles and Systems § 1192.79 Floors, steps and thresholds. (a) Floor surfaces on aisles, step treads, places for standees, and areas where wheelchair and mobility aid users are to be...

Effect of O horizon and Forest Harvest Residue Manipulations on Soil Organic Matter Content and Composition of a Loblolly Pine Plantation in the Southeastern United States

NASA Astrophysics Data System (ADS)

Hatten, J.; Mack, J.; Dewey, J.; Sucre, E.; Leggett, Z.

2012-04-01

Forest harvest residues and forest floor materials are significant sources of mineral soil organic matter and nutrients for regenerating and establishing forests. Harvest residues in particular are occasionally removed, piled, or burned following harvesting. While the forest floor is never purposely removed during operational harvesting and site preparation, they could become in high demand as bioenergy markets develop. Weyerhaeuser Company established an experimental study to evaluate the effect of forest-floor manipulation on site productivity and soil carbon. This study was installed in a loblolly pine plantation near Millport, Alabama, USA on the Upper Gulf Coastal Plain to test both extremes from complete removal of harvest residues and forest floor to doubling of these materials. This study has been continuously monitored since its establishment in 1994. We have examined the effects of varying forest floor levels on the biomass, soil carbon content, and soil carbon composition in the context of these management activities. Above- and below-ground productivity, soil moisture, soil temperature, and nutrient dynamics have been related to soil organic carbon in mineral soil size/density fractionation and lignin and cutin biomarkers from the cupric oxide (CuO) oxidation technique. We have found that while removing litter and harvest residues has little effect on biomass production and soil carbon, importing litter and harvest residues increases forest productivity and soil carbon content. Interestingly, increased carbon was observed in all depths assessed (O horizon, 0-20, 20-40, and 40-60cm) suggesting that this practice may sequester organic carbon in deep soil horizons. Our biomarker analysis indicated that importing litter and harvest residues increased relative contributions from above ground sources at the 20-40cm depth and increased relative contributions from belowground sources at the 40-60cm depth. These results suggest that organic matter manipulations in managed forests can have significant effects on deep soil carbon that may be resistant to mineralization or the effects of other perturbations such as climate change.

Warm-adapted microbial communities enhance their carbon-use efficiency in warmed soils

NASA Astrophysics Data System (ADS)

Rousk, Johannes; Frey, Serita

2017-04-01

Ecosystem models predict that climate warming will stimulate microbial decomposition of soil carbon (C), resulting in a positive feedback to increasing temperatures. The current generation of models assume that the temperature sensitivities of microbial processes do not respond to warming. However, recent studies have suggested that the ability of microbial communities to adapt to warming can lead both strengthened and weakened feedbacks. A further complication is that the balance between microbial C used for growth to that used for respiration - the microbial carbon-use efficiency (CUE) - also has been shown through both modelling and empirical study to respond to warming. In our study, we set out to assess how chronic warming (+5°C over ambient during 9 years) of a temperate hardwood forest floor (Harvard Forest LTER, USA) affected temperature sensitivities of microbial processes in soil. To do this, we first determined the temperature relationships for bacterial growth, fungal growth, and respiration in plots exposed to warmed or ambient conditions. Secondly, we parametrised the established temperature functions microbial growth and respiration with plot-specific measured soil temperature data at a hourly time-resolution over the course of 3 years to estimate the real-time variation of in situ microbial C production and respiration. To estimate the microbial CUE, we also divided the microbial C production with the sum of microbial C production and respiration as a proxy for substrate use. We found that warm-adapted bacterial and fungal communities both shifted their temperature relationships to grow at higher rates in warm conditions which coincided with reduced rates at cool conditions. As such, their optimal temperature (Topt), minimum temperature (Tmin) and temperature sensitivity (Q10) were all increased. The temperature relationship for temperature, in contrast, was only marginally shifted in the same direction, but at a much smaller effect size, with negligible changes in Topt, Tmin and Q10 for respiration. When these physiological changes were scaled with soil temperature data to estimate real-time variation in situ during three years, the warm-adaptation resulted in elevated microbial CUEs during summer temperatures in warm-adapted communities and reduced microbial CUEs during winter temperatures. By comparing simulated microbial CUEs in cold-adapted communities exposed to warmed conditions to microbial CUEs in the warm-adapted communities exposed to those temperatures, we could demonstrate that the shifts towards warm-adapted microbial communities had selected for elevated microbial CUEs for the full range of in situ soil temperatures during three years. Our results suggest that microbial adaptation to warming will enhance microbial CUEs, shifting their balance of C use from respiration to biomass production. If our estimates scale to ecosystem level, this would imply that warm-adapted microbial communities will ultimately have the potential to store more C in soil than their cold-adapted counter parts could when exposed to warmer temperatures.

Sorptive fractionation of organic matter and formation of organo-hydroxy-aluminum complexes during litter biodegradation in the presence of gibbsite

NASA Astrophysics Data System (ADS)

Heckman, K.; Grandy, A. S.; Gao, X.; Keiluweit, M.; Wickings, K.; Carpenter, K.; Chorover, J.; Rasmussen, C.

2013-11-01

Solid and aqueous phase Al species are recognized to affect organic matter (OM) stabilization in forest soils. However, little is known about the dynamics of formation, composition and dissolution of organo-Al hydroxide complexes in microbially-active soil systems, where plant litter is subject to microbial decomposition in close proximity to mineral weathering reactions. We incubated gibbsite-quartz mineral mixtures in the presence of forest floor material inoculated with a native microbial consortium for periods of 5, 60 and 154 days. At each time step, samples were density separated into light (<1.6 g cm-3), intermediate (1.6-2.0 g cm-3), and heavy (>2.0 g cm-3) fractions. The light fraction was mainly comprised of particulate organic matter, while the intermediate and heavy density fractions contained moderate and large amounts of Al-minerals, respectively. Multi-method interrogation of the fractions indicated the intermediate and heavy fractions differed both in mineral structure and organic compound composition. X-ray diffraction analysis and SEM/EDS of the mineral component of the intermediate fractions indicated some alteration of the original gibbsite structure into less crystalline Al hydroxide and possibly proto-imogolite species, whereas alteration of the gibbsite structure was not evident in the heavy fraction. DRIFT, Py-GC/MS and STXM/NEXAFS results all showed that intermediate fractions were composed mostly of lignin-derived compounds, phenolics, and polysaccharides. Heavy fraction organics were dominated by polysaccharides, and were enriched in proteins, N-bearing compounds, and lipids. The source of organics appeared to differ between the intermediate and heavy fractions. Heavy fractions were enriched in 13C with lower C/N ratios relative to intermediate fractions, suggesting a microbial origin. The observed differential fractionation of organics among hydroxy-Al mineral types suggests that microbial activity superimposed with abiotic mineral-surface-mediated fractionation leads to strong density differentiation of organo-mineral complex composition even over the short time scales probed in these incubation experiments. The data highlight the strong interdependency of mineral transformation, microbial community activity, and organic matter stabilization during biodegradation.

Cadmium contamination of wood ash and fire-treated coniferous humus: Effect on soil respiration

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

Fritze, H.; Kapanen, A.; Vanhala, P.

Atmospheric acidic deposition is known to affect soil fertility and in many countries, liming has been used to counteract anthropogenic soil acidification in coniferous forest soils. Other measures used to improve the acid neutralization capacity of forest soils are wood ash application and prescribed burning. In both cases, ash is deposited on the forest floor, resulting in a pH increase in the humus layer. Currently, application of forests with wood ash is under discussion in Finland, since the naturally occurring cadmium of forest trees is concentrated into the wood ash which then contains between 4 and 20 {mu} g{sup {minus}1}more » of dry matter. Microbes are essential for maintaining soil fertility and plant growth because they play a fundamental role in nutrient availability. Soil respiration rate, which is an indicator of the microbially-mediated nutrient turnover rate, is decreased by addition of cadmium to the soil environment. In this paper we report on the effects of cadmium addition on the soil respiration rate of forest humus having received wood ash or fire treatments. The underlying objectives of this study were: (i) to determine the cadmium level which decreases the soil respiration of a Vaccinium site type forest humus to half of its original value (EC{sub 50}), (ii) to estimate how the forest treatments influence the EC{sub 50}, and (iii) to discuss the effect of Cd addition provided by wood ash on the nutrient mineralization rate. 17 refs., 2 figs., 2 tabs.« less

Soil organic matter quantity and quality shape microbial community compositions of subtropical broadleaved forests.

PubMed

Ding, Junjun; Zhang, Yuguang; Wang, Mengmeng; Sun, Xin; Cong, Jing; Deng, Ye; Lu, Hui; Yuan, Tong; Van Nostrand, Joy D; Li, Diqiang; Zhou, Jizhong; Yang, Yunfeng

2015-10-01

As two major forest types in the subtropics, broadleaved evergreen and broadleaved deciduous forests have long interested ecologists. However, little is known about their belowground ecosystems despite their ecological importance in driving biogeochemical cycling. Here, we used Illumina MiSeq sequencing targeting 16S rRNA gene and a microarray named GeoChip targeting functional genes to analyse microbial communities in broadleaved evergreen and deciduous forest soils of Shennongjia Mountain of Central China, a region known as 'The Oriental Botanic Garden' for its extraordinarily rich biodiversity. We observed higher plant diversity and relatively richer nutrients in the broadleaved evergreen forest than the deciduous forest. In odds to our expectation that plant communities shaped soil microbial communities, we found that soil organic matter quantity and quality, but not plant community parameters, were the best predictors of microbial communities. Actinobacteria, a copiotrophic phylum, was more abundant in the broadleaved evergreen forest, while Verrucomicrobia, an oligotrophic phylum, was more abundant in the broadleaved deciduous forest. The density of the correlation network of microbial OTUs was higher in the broadleaved deciduous forest but its modularity was smaller, reflecting lower resistance to environment changes. In addition, keystone OTUs of the broadleaved deciduous forest were mainly oligotrophic. Microbial functional genes associated with recalcitrant carbon degradation were also more abundant in the broadleaved deciduous forests, resulting in low accumulation of organic matters. Collectively, these findings revealed the important role of soil organic matter in shaping microbial taxonomic and functional traits. © 2015 John Wiley & Sons Ltd.

Input and output budgets of radiocesium concerning the forest floor in the mountain forest of Fukushima released from the TEPCO's Fukushima Dai-ichi nuclear power plant accident.

PubMed

Niizato, Tadafumi; Abe, Hironobu; Mitachi, Katsuaki; Sasaki, Yoshito; Ishii, Yasuo; Watanabe, Takayoshi

2016-09-01

Estimations of radiocesium input and output concerning the forest floor within a mountain forest region have been conducted in the north and central part of the Abukuma Mountains of Fukushima, northeast Japan, after a 2-3 year period following the TEPCO Fukushima Dai-ichi nuclear power plant accident. The radiocesium input and output associated with surface washoff, throughfall, stemflow, and litterfall processes at experimental plots installed on the forest floor of evergreen Japanese cedars and deciduous Konara oaks have been monitored. Despite the high output potential in the mountainous forest of Fukushima, the results at both monitoring locations show the radiocesium input to be 4-50 times higher than the output during the summer monsoon in Fukushima. These results indicate that the radiocesium tends to be preserved in the forest ecosystem due to extremely low output ratios (0.05%-0.19%). Thus, the associated fluxes throughout the circulation process are key issues for the projecting the environmental fate of the radiocesium levels, along with the subsequent reconstruction of life emphasized within the setting. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Longleaf pine site response to repeated fertilization and forest floor removal by raking and prescribed burning

Treesearch

Kim Ludovici; Robert Eaton; Stanley Zarnoch

2018-01-01

Removal of forest floor litter by pine needle raking and prescribed burning is a common practice in longleaf pine (Pinus palustris Mill.) stands on Coastal Plain sites in the Southeastern United States. Repeated removal of litter by raking and the loss of surface organic matter from controlled burns can affect the...

Explaining the apparent resiliency of loblolly pine plantation to organic matter removal

Treesearch

Jeff A. Hatten; Eric B. Surce; Zakiya Leggett; Jason Mack; Scott D. Roberts; Janet Dewey; Brian Strahm

2015-01-01

We utilized 15-year measurements from an organic matter manipulation experiment in a loblolly pine plantation in the Upper Coastal Plain of Alabama to examine the apparent resiliency of a loblolly pine stand to organic matter removal. Treatments included complete removal of harvest residues and forest floor (removed), doubling of harvest residues and forest floor (...

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...

Divergence of dominant factors in soil microbial communities and functions in forest ecosystems along a climatic gradient

NASA Astrophysics Data System (ADS)

Xu, Zhiwei; Yu, Guirui; Zhang, Xinyu; He, Nianpeng; Wang, Qiufeng; Wang, Shengzhong; Xu, Xiaofeng; Wang, Ruili; Zhao, Ning

2018-03-01

Soil microorganisms play an important role in regulating nutrient cycling in terrestrial ecosystems. Most of the studies conducted thus far have been confined to a single forest biome or have focused on one or two controlling factors, and few have dealt with the integrated effects of climate, vegetation, and soil substrate availability on soil microbial communities and functions among different forests. In this study, we used phospholipid-derived fatty acid (PLFA) analysis to investigate soil microbial community structure and extracellular enzymatic activities to evaluate the functional potential of soil microbes of different types of forests in three different climatic zones along the north-south transect in eastern China (NSTEC). Both climate and forest type had significant effects on soil enzyme activities and microbial communities with considerable interactive effects. Except for soil acid phosphatase (AP), the other three enzyme activities were much higher in the warm temperate zone than in the temperate and the subtropical climate zones. The soil total PLFAs and bacteria were much higher in the temperate zone than in the warm temperate and the subtropical zones. The soil β-glucosidase (BG) and N-acetylglucosaminidase (NAG) activities were highest in the coniferous forest. Except for the soil fungi and fungi-bacteria (F/B), the different groups of microbial PLFAs were much higher in the conifer broad-leaved mixed forests than in the coniferous forests and the broad-leaved forests. In general, soil enzyme activities and microbial PLFAs were higher in primary forests than in secondary forests in temperate and warm temperate regions. In the subtropical region, soil enzyme activities were lower in the primary forests than in the secondary forests and microbial PLFAs did not differ significantly between primary and secondary forests. Different compositions of the tree species may cause variations in soil microbial communities and enzyme activities. Our results showed that the main controls on soil microbes and functions vary in different climatic zones and that the effects of soil moisture content, soil temperature, clay content, and the soil N / P ratio were considerable. This information will add value to the modeling of microbial processes and will contribute to carbon cycling in large-scale carbon models.

36 CFR 1192.99 - Floors, steps and thresholds.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Floors, steps and thresholds... Commuter Rail Cars and Systems § 1192.99 Floors, steps and thresholds. (a) Floor surfaces on aisles, step... shall be slip-resistant. (b) All thresholds and step edges shall have a band of color(s) running the...

Long lasting effects of the conversion from natural forest to poplar plantation on soil microbial communities.

PubMed

Vitali, Francesco; Mastromei, Giorgio; Senatore, Giuliana; Caroppo, Cesarea; Casalone, Enrico

2016-01-01

In this study, we evaluate the long-lasting effects on soil microbial communities of a change within a single land-use category, specifically the conversion from natural forest to forest plantation. To minimize the effects of impacts other than land-use (i.e., climatic and anthropogenic), we chose three sites within a Natural Park, with homogeneous orographic and soil texture characteristics. We compared microbial diversity in a total of 156 soil samples from two natural mixed forests and a similar forest converted to poplar plantation about thirty years ago. The diversity and structure of bacterial and fungal communities were investigated by terminal restriction fragments length polymorphism (T-RFLP) analysis of the 16S-rRNA gene and the ITS-rDNA regions, respectively. Bacterial and fungal communities from the forest plantation, compared to those from natural forest soils, showed different community structure and lower α-diversity values, consistently with the significantly higher pH values and lower organic matter content of those soils. β-diversity values, the number of measured and estimated dominant OTUs, and their distribution among the three sites showed that microbial communities from the two natural forests were much more similar to each other than they were to communities from the poplar plantation, suggesting an effect of the forest conversion on the composition and diversity of soil microbial communities. α-diversity in cultivated forest soils had narrower temporal fluctuations than in natural forest soils, suggesting higher temporal stability of microbial communities. Overall, we demonstrated that the conversion from natural forest to forest plantation altered soil microbial communities, changing their structure, lowering their diversity, and causing a spatial and temporal homogenization. Copyright © 2015 Elsevier GmbH. All rights reserved.

76 FR 14898 - Daniel Boone National Forest Resource Advisory Committee

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-18

... DEPARTMENT OF AGRICULTURE Forest Service Daniel Boone National Forest Resource Advisory Committee AGENCY: Forest Service, USDA. ACTION: Notice of meeting. SUMMARY: The Daniel Boone National Forest... basement floor. Written comments should be sent to Kimberly Morgan, Daniel Boone National Forest, 1700...

Lead sequestration and species redistribution during soil organic matter decomposition

USGS Publications Warehouse

Schroth, A.W.; Bostick, B.C.; Kaste, J.M.; Friedland, A.J.

2008-01-01

The turnover of soil organic matter (SOM) maintains a dynamic chemical environment in the forest floor that can impact metal speciation on relatively short timescales. Here we measure the speciation of Pb in controlled and natural organic (O) soil horizons to quantify changes in metal partitioning during SOM decomposition in different forest litters. We provide a link between the sequestration of pollutant Pb in O-horizons, estimated by forest floor Pb inventories, and speciation using synchrotron-based X-ray fluorescence and X-ray absorption spectroscopy. When Pb was introduced to fresh forest Oi samples, it adsorbed primarily to SOM surfaces, but as decomposition progressed over two years in controlled experiments, up to 60% of the Pb was redistributed to pedogenic birnessite and ferrihydrite surfaces. In addition, a significant fraction of pollutant Pb in natural soil profiles was associated with similar mineral phases (???20-35%) and SOM (???65-80%). Conifer forests have at least 2-fold higher Pb burdens in the forest floor relative to deciduous forests due to more efficient atmospheric scavenging and slower organic matter turnover. We demonstrate that pedogenic minerals play an important role in surface soil Pb sequestration, particularly in deciduous forests, and should be considered in any assessment of pollutant Pb mobility. ?? 2008 American Chemical Society.

[Microsite characteristics of pit and mound and their effects on the vegetation regeneration in Pinus koraiensis-dominated broadleaved mixed forest].

PubMed

Du, Shan; Duan, Wen-Biao; Wang, Li-Xia; Chen, Li-Xin; Wei, Quan-Shuai; Li, Meng; Wang, Li-dong

2013-03-01

Abstract: An investigation was conducted in a 2.55 hm2 plot of Pinus koraiensis-dominated broad-leaved mixed forest to study the microsite characteristics of pit and mound formed by 42 treefalls and the status of vegetation regeneration on the microsites. The soil water content, soil temperature, relative air humidity, and photosynthetically active radiation (PAR) on five microsites (mound top, mound face, pit wall, pit bottom, and intact forest floor) were measured. Among the five mirosites, mound top had the highest PAR (527.9 micromol.m-2.s-1 ) while intact forest floor had the lowest one (58.7 micromol.m-2.s-), mound top had the highest soil temperature (16.0 degrees C) but pit bottom had the lowest one (13.3 degrees C), pit bottom had the highest soil water content (34.6%) but mound face had the lowest one (0.5%), and intact forest floor had the highest relative air humidity (75.9%) but mound top had the lowest one (68.0%). The frequency of forming pit/ mound complex by the tree species was decreased in the order of Pinus koraiensis (42. 9%) >Picea asperata (31.0%) > Betula platyphylla (16.7%) > Abies fabri (7. 1%) > Prunus padus (2.4%). Among the 42 treefalls, two-thirds of them were in northwest direction. The treefalls volume had significant positive correlations with pit depth, pit length, mound height, and mound width, but negative correlation with mound thickness. The treefall mean diameter at breast height had significant positive correlations with pit width (r=0.328, P=0.017) and pit length (r=0.527, P= 0). The tree species richness at the microsites decreased in the order of intact forest floor > pit > mound, and the tree species coverage was in the sequence of intact forest floor > pit > mound.

Manganese and Mn/Ca ratios in soil and vegetation in forests across the northeastern US: Insights on spatial Mn enrichment.

PubMed

Richardson, J B

2017-03-01

Manganese (Mn) cycling in the Critical Zone is important because of its role as an essential nutrient and potential toxicity to plants and organisms. Quantifying Mn enrichment in terrestrial environments has been limited since Mn is monoisotopic. However, elemental ratios of Mn/Ca ratios may be used to determine spatial Mn enrichment and in aboveground and belowground pools. The objectives of this study were to quantify the spatial variation in Mn concentrations and Mn/Ca ratios in foliage, bolewood, forest floor, and mineral soil horizons across the northeastern United States and compare Mn/Ca ratios to estimate enrichment. Forest floor and mineral soil samples were collected from 26 study sites across the northeastern United States and analyzed by strong acid digestion. Foliage and bolewood was collected from 12 of the 26 sites and analyzed for total Mn and Ca. Our results show forest floor and mineral soil horizon Mn concentrations and Mn/Ca ratios were higher at Pennsylvania and New York sites than New Hampshire and Vermont sites. Using a modified isotope equation, enrichment factors (EF) for Mn/Ca ratios were calculated to be ~3.6 in the forest floor, upper and lower mineral soil horizons at sites in New York and Pennsylvania compared to reference sites in New Hampshire and Vermont. Foliar and bolewood Mn concentrations also decreased from Pennsylvania towards New Hampshire. Moreover, foliar and bolewood Mn concentrations were strongly correlated to forest floor, upper, and lower mineral soil Mn concentrations. It was hypothesized that internal cycling (uptake, throughfall, and litterfall) of Mn controls retention of enriched Mn in forests. Geologic influences from a lithologic gradient and soil pH gradient could also influence Mn enrichment in addition to Mn pollution. Ratios of Mn/Ca and other elemental ratios hold promise as geochemical tracers but require further development. Copyright © 2016 Elsevier B.V. All rights reserved.

Changes in microbial community characteristics and soil organic matter with nitrogen additions in two tropical forests.

PubMed

Cusack, Daniela F; Silver, Whendee L; Torn, Margaret S; Burton, Sarah D; Firestone, Mary K

2011-03-01

Microbial communities and their associated enzyme activities affect the amount and chemical quality of carbon (C) in soils. Increasing nitrogen (N) deposition, particularly in N-rich tropical forests, is likely to change the composition and behavior of microbial communities and feed back on ecosystem structure and function. This study presents a novel assessment of mechanistic links between microbial responses to N deposition and shifts in soil organic matter (SOM) quality and quantity. We used phospholipid fatty acid (PLFA) analysis and microbial enzyme assays in soils to assess microbial community responses to long-term N additions in two distinct tropical rain forests. We used soil density fractionation and 13C nuclear magnetic resonance (NMR) spectroscopy to measure related changes in SOM pool sizes and chemical quality. Microbial biomass increased in response to N fertilization in both tropical forests and corresponded to declines in pools of low-density SOM. The chemical quality of this soil C pool reflected ecosystem-specific changes in microbial community composition. In the lower-elevation forest, there was an increase in gram-negative bacteria PLFA biomass, and there were significant losses of labile C chemical groups (O-alkyls). In contrast, the upper-elevation tropical forest had an increase in fungal PLFAs with N additions and declines in C groups associated with increased soil C storage (alkyls). The dynamics of microbial enzymatic activities with N addition provided a functional link between changes in microbial community structure and SOM chemistry. Ecosystem-specific changes in microbial community composition are likely to have far-reaching effects on soil carbon storage and cycling. This study indicates that microbial communities in N-rich tropical forests can be sensitive to added N, but we can expect significant variability in how ecosystem structure and function respond to N deposition among tropical forest types.

Assessment of soil calcium status in red spruce forests in the northeastern United States

USGS Publications Warehouse

Lawrence, G.B.; David, M.B.; Bailey, S.W.; Shortle, W.C.

1997-01-01

Long-term changes in concentrations of available Ca in soils of red spruce forests have been documented, but remaining questions about the magnitude and regional extent of these changes have precluded an assessment of the current and future status of soil Ca. To address this problem, soil samples were collected in 1992-93 from 12 sites in New York, Vermont, New Hampshire, and Maine to provide additional data necessary to synthesize all available research results on soil Ca in red spruce forests. Sites were chosen to encompass the range of environmental conditions experienced by red spruce. Concentrations of exchangeable Ca ranged from 2.13 to 21.6 cmol(c) kg-1 in the Oa horizon, and from 0.11 to 0.68 cmol(c) kg-1 in the upper 10 cm of the B horizon. These measurements expanded the range of exchangeable Ca reported in the literature for both horizons in northeastern red spruce forests. Exchangeable Ca was the largest Ca fraction in the forest floor at most sites (92% of acid-extractable Ca), but mineral Ca was the largest fraction at the three sites that also had the highest mineral-matter concentrations. The primary factor causing variability in Ca concentrations among sites was the mineralogy of parent material, but exchangeable concentrations in the B horizon of all sites were probably reduced by acidic deposition. Because the majority of Ca in the forest floor is in a readily leachable form, and Ca inputs to the forest floor from the mineral soil and atmospheric deposition have been decreasing in recent decades, the previously documented decreases in Ca concentrations in the forest floor over previous decades may extend into the future.

Comparing jack pine slash and forest floor moisture contents and National Fire Danger Rating System predictions.

Treesearch

Robert M. Loomis; William A. Main

1980-01-01

Relations between certain slash and forest floor moisture contents and the applicable estimated time lag fuel moistures of the National Fire Danger Rating System were investigated for 1-year-old jack pine fuel types in northeastern Minnesota and central Lower Michigan. Only approximate estimates of actual fuel moisture are possible fore the relations determined, thus...

Viability of litter-stored Pinus taeda L. seeds after simulated prescribed winter burns

Treesearch

Michael D. Cain; Michael G. Shelton

1998-01-01

Stratified loblolly pine (Pinus taeda L.) seeds were placed at three depths in a reconstructed forest floor and subjected to simulated prescribed winter burns. Within the forest floor, pine seeds were placed at the L/upper-F interface, upper-F/lower-F interface, and lower-F/mineral-soil interface. Wind was generated by electric box-fans. Seeds that...

Variation in soil and forest floor characteristics along gradients of ericaceous, evergreen shrub cover in the southern Appalachians

Treesearch

Jonatha L. Horton; Barton D. Clinton; John F. Walker; Colin M. Beir; Erik T. Nilsen

2009-01-01

Ericaceous shrubs can influence soil properties in many ecosystems. In this study, we examined how soil and forest floor properties vary among sites with different ericaceous evergreen shrub basal area in the southern Appalachian mountains. We randomly located plots along transects that included open understories and understories with varying amounts of Rhododendron...

Viability of litter-stored Quercus falcata Michx. acorns after simulated prescribed winter burns

Treesearch

Michael D. Cain; Michael G. Shelton

1998-01-01

Partially stratified (11 days) southern red oak (Quercus falcata Michx.) acorns were placed at three depths in a reconstructed forest floor and subjected to simulated prescribed winter burns. Within the forest floor, acorns were placed within the L layer, at the upper-F/ lower-F interface, and at the lower-F/mineral-soil interface. Winds for a...

Light-induced diurnal pattern of methane exchange in a boreal forest

NASA Astrophysics Data System (ADS)

Sundqvist, Elin; Crill, Patrick; Mölder, Meelis; Vestin, Patrik; Lindroth, Anders

2013-04-01

Boreal forests represents one third of the Earth's forested land surface area and is a net sink of methane and an important component of the atmospheric methane budget. Methane is oxidized in well-aerated forest soils whereas ponds and bog soils are sources of methane. Besides the microbial processes in the soil also forest vegetation might contribute to methane exchange. Due to a recent finding of methane consumption by boreal plants that correlated with photosynthetic active radiation (PAR), we investigate the impact of PAR on soil methane exchange at vegetated plots on the forest floor. The study site, Norunda in central Sweden, is a 120 years old boreal forest stand, dominated by Scots pine and Norway spruce. We used continuous chamber measurements in combination with a high precision laser gas analyzer (Los Gatos Research), to measure the methane exchange at four different plots in July-November 2009, and April-June 2010. The ground vegetation consisted almost entirely of mosses and blueberry-shrubs. Two of the plots acted as stable sinks of methane whereas the other two plots shifted from sinks to sources during very wet periods. The preliminary results show a clear diurnal pattern of the methane exchange during the growing season, which cannot be explained by temperature. The highest consumption occurs at high PAR levels. The amplitude of the diurnal methane exchange during the growing season is in the order of 10 μmol m-2 h-1. This indicates that besides methane oxidation by methanotrophs in the soil there is an additional removal of methane at soil level by a process related to ground vegetation.

36 CFR 1192.117 - Floors, steps and thresholds.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Floors, steps and thresholds... Intercity Rail Cars and Systems § 1192.117 Floors, steps and thresholds. (a) Floor surfaces on aisles, step.... (b) All step edges and thresholds shall have a band of color(s) running the full width of the step or...

Forest floor community metatranscriptomes identify fungal and bacterial responses to N deposition in two maple forests

DOE PAGES

Hesse, Cedar N.; Mueller, Rebecca C.; Vuyisich, Momchilo; ...

2015-04-23

Anthropogenic N deposition alters patterns of C and N cycling in temperate forests, where forest floor litter decomposition is a key process mediated by a diverse community of bacteria and fungi. To track forest floor decomposer activity we generated metatranscriptomes that simultaneously surveyed the actively expressed bacterial and eukaryote genes in the forest floor, to compare the impact of N deposition on the decomposers in two natural maple forests in Michigan, USA, where replicate field plots had been amended with N for 16 years. Site and N amendment responses were compared using about 74,000 carbohydrate active enzyme transcript sequences (CAZymes)more » in each metatranscriptome. Parallel ribosomal RNA (rRNA) surveys of bacterial and fungal biomass and taxonomic composition showed no significant differences in either biomass or OTU richness between the two sites or in response to N. Site and N amendment were not significant variables defining bacterial taxonomic composition, but they were significant for fungal community composition, explaining 17 and 14% of the variability, respectively. The relative abundance of expressed bacterial and fungal CAZymes changed significantly with N amendment in one of the forests, and N-response trends were also identified in the second forest. Although the two ambient forests were similar in community biomass, taxonomic structure and active CAZyme profile, the shifts in active CAZyme profiles in response to N-amendment differed between the sites. One site responded with an over-expression of bacterial CAZymes, and the other site responded with an over-expression of both fungal and different bacterial CAZymes. Both sites showed reduced representation of fungal lignocellulose degrading enzymes in N-amendment plots. The metatranscriptome approach provided a holistic assessment of eukaryote and bacterial gene expression and is applicable to other systems where eukaryotes and bacteria interact.« less

Tropical Land Use Conversion Effects on Soil Microbial Community Structure and Function: Emerging Patterns and Knowledge Gaps

NASA Astrophysics Data System (ADS)

Seeley, M.; Marin-Spiotta, E.

2016-12-01

Modifications in vegetation due to land use conversions (LUC) between primary forests, pasture, cropping systems, tree plantations, and secondary forests drive shifts in soil microbial communities. These microbial community alterations affect carbon sequestration, nutrient cycling, aboveground biomass, and numerous other soil processes. Despite their importance, little is known about soil microbial organisms' response to LUC, especially in tropical regions where LUC rates are greatest. This project identifies current trends and uncertainties in tropical soil microbiology by comparing 56 published studies on LUC in tropical regions. This review indicates that microbial biomass and functional groups shifted in response to LUC, supporting demonstrated trends in changing soil carbon stocks due to LUC. Microbial biomass was greatest in primary forests when compared to secondary forests and in all forests when compared to both cropping systems and tree plantations. No trend existed when comparing pasture systems and forests, likely due to variations in pasture fertilizer use. Cropping system soils had greater gram positive and less gram negative bacteria than forest soils, potentially resulting in greater respiration of older carbon stocks in agricultural soils. Bacteria dominated primary forests while fungal populations were greatest in secondary forests. To characterize changes in microbial communities resulting from land use change, research must reflect the biophysical variation across the tropics. A chi-squared test revealed that the literature sites represented mean annual temperature variation across the tropics (p-value=0.66).

Microbiologic evaluation of microfiber mops for surface disinfection.

PubMed

Rutala, William A; Gergen, Maria F; Weber, David J

2007-11-01

Recently, health care facilities have started to use a microfiber mopping technique rather than a conventional, cotton string mop to clean floors. The effectiveness of microfiber mops to reduce microbial levels on floors was investigated. We compared the efficacy of microfiber mops with that of conventional, cotton string mops in 3 test conditions (cotton mop and standard wringer bucket, microfiber mop and standard wringer bucket, microfiber system). Twenty-four rooms were evaluated for each test condition. RODAC plates containing D/E Neutralizing Agar were used to assess "precleaning" and "postcleaning" microbial levels. The microfiber system demonstrated superior microbial removal compared with cotton string mops when used with a detergent cleaner (95% vs 68%, respectively). The use of a disinfectant did not improve the microbial elimination demonstrated by the microfiber system (95% vs 95%, respectively). However, use of disinfectant did significantly improve microbial removal when a cotton string mop was used (95% vs 68%, respectively). The microfiber system demonstrated superior microbial removal compared with cotton string mops when used with a detergent cleaner. The use of a disinfectant did not improve the microbial elimination demonstrated by the microfiber system.

A new mechanism for calcium loss in forest-floor soils

USGS Publications Warehouse

Lawrence, G.B.; David, M.B.; Shortle, W.C.

1995-01-01

CALCIUM is the fifth most abundant element in trees, and is an essential component for wood formation and the maintenance of cell walls. Depletion of Ca from the rooting zone can result in acidification of soil1 and surface water2 and possibly growth decline and dieback of red spruce3,4. During the past six decades, concentrations of root-available Ca (exchangeable and acid-ex tract able forms) in forest-floor soils have decreased in the northeastern United States5,6. Both net forest growth and acid deposition have been put forth as mechanisms that can account for this Ca depletion5,6. Here, however, we present data collected in red spruce forests in the northeastern United States that are inconsistent with either of these mechanisms. We propose that aluminium, mobilized in the mineral soil by acid deposition, is transported into the forest floor in a reactive form that reduces storage of Ca, and thus its availability for root uptake. This results in potential stress to trees and, by increasing the demand for Ca, also decreases neutralization of drainage waters, thereby leading to acidification of lakes and streams.

Changes in soil fertility following prescribed burning on Coastal Plain pine sites

Treesearch

William H. McKee

1982-01-01

Soil and forest floor samples were collected from four prescribed burning studies in the Atlantic and Gulf Coastal Plains. The surface textures of soils ranged from sands to silt loams and the drainage classes from well to poorly drained. Burning treatments had been in force from 8 to 65 years. Reduction of the forest floor and its chemical constituents was related to...

Chemistry of burning the forest floor during the FROSTFIRE experimental burn, interior Alaska, 1999.

Treesearch

J.W. Harden; J.C. Neff; D.V. Sandberg; M.R. Turetsky; R. Ottmar; G. Gleixner; T.L. Fries; K.L. Manies

2004-01-01

Wildfires represent one of the most common disturbances in boreal regions, and have the potential to reduce C, N, and Hg stocks in soils while contributing to atmospheric emissions. Organic soil layers of the forest floor were sampled before and after the FROSTFIRE experimental burn in interior Alaska, and were analyzed for bulk density, major and trace elements, and...

Fire Ecology of Seeds from Rubus Spp.: A Competitor During Natural Pine Regeneration

Treesearch

Michael D. Cain; Michael G. Shelton

1999-01-01

Air-dried blackbeny (Rubus spp.) fruits were placed at three depths in a reconstructed forest floor and subjected to a simulated prescribed summer bum. Within the forest floor, fruits were placed on the L layer, at the upper-F/lower-F interface, and at the lower-F/mineral-soil interface. Wind for a headfire was generated by electric boxfans....

Acute physiological stress and mortality following fire in a long-unburned longleaf pine ecosystem

Treesearch

J.J. O’Brien; J.K. Hiers; R.J. Mitchell; J.M. Varner; K. Mordecai

2010-01-01

One important legacy of fire exclusion in ecosystems dependent upon frequent fire is the development of organic soil horizons (forest floor) that can be colonized by fine roots. When fire is re-introduced, the forest floor is often consumed by fire and heavy overstory mortality, often delayed by months, results. We hypothesized that the delayed post-fire tree mortality...

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...

Seeing the Landscape and the Forest Floor: Changes Made to Improve the Connectivity of Concepts in a Hybrid Problem-Based Learning Curriculum

ERIC Educational Resources Information Center

O'Neill, Geraldine; Hung, Woei

2010-01-01

Problem-based learning (PBL) curricula utilise authentic problems that are based in the real-world of practice. This very characteristic enables students to develop an intimate knowledge about the intricacies of practice, metaphorically, seeing the details of the forest floor. However, it is equally important for students to develop an overall…

Differential controls on soil carbon density and mineralization among contrasting forest types in a temperate forest ecosystem.

PubMed

You, Ye-Ming; Wang, Juan; Sun, Xiao-Lu; Tang, Zuo-Xin; Zhou, Zhi-Yong; Sun, Osbert Jianxin

2016-03-01

Understanding the controls on soil carbon dynamics is crucial for modeling responses of ecosystem carbon balance to global change, yet few studies provide explicit knowledge on the direct and indirect effects of forest stands on soil carbon via microbial processes. We investigated tree species, soil, and site factors in relation to soil carbon density and mineralization in a temperate forest of central China. We found that soil microbial biomass and community structure, extracellular enzyme activities, and most of the site factors studied varied significantly across contrasting forest types, and that the associations between activities of soil extracellular enzymes and microbial community structure appeared to be weak and inconsistent across forest types, implicating complex mechanisms in the microbial regulation of soil carbon metabolism in relation to tree species. Overall, variations in soil carbon density and mineralization are predominantly accounted for by shared effects of tree species, soil, microclimate, and microbial traits rather than the individual effects of the four categories of factors. Our findings point to differential controls on soil carbon density and mineralization among contrasting forest types and highlight the challenge to incorporate microbial processes for constraining soil carbon dynamics in global carbon cycle models.

Differential controls on soil carbon density and mineralization among contrasting forest types in a temperate forest ecosystem

PubMed Central

You, Ye-Ming; Wang, Juan; Sun, Xiao-Lu; Tang, Zuo-Xin; Zhou, Zhi-Yong; Sun, Osbert Jianxin

2016-01-01

Understanding the controls on soil carbon dynamics is crucial for modeling responses of ecosystem carbon balance to global change, yet few studies provide explicit knowledge on the direct and indirect effects of forest stands on soil carbon via microbial processes. We investigated tree species, soil, and site factors in relation to soil carbon density and mineralization in a temperate forest of central China. We found that soil microbial biomass and community structure, extracellular enzyme activities, and most of the site factors studied varied significantly across contrasting forest types, and that the associations between activities of soil extracellular enzymes and microbial community structure appeared to be weak and inconsistent across forest types, implicating complex mechanisms in the microbial regulation of soil carbon metabolism in relation to tree species. Overall, variations in soil carbon density and mineralization are predominantly accounted for by shared effects of tree species, soil, microclimate, and microbial traits rather than the individual effects of the four categories of factors. Our findings point to differential controls on soil carbon density and mineralization among contrasting forest types and highlight the challenge to incorporate microbial processes for constraining soil carbon dynamics in global carbon cycle models. PMID:26925871

Soil ploughing for forest regeneration leads to changes in carbon decomposition - a case study with stable isotopes

NASA Astrophysics Data System (ADS)

Stróżecki, Marcin; Silvennoinen, Hanna; Strzeliński, Paweł; Chojnicki, Bogdan Heronim

2018-04-01

It is important to quantify carbon decomposition to assess the reforestation impact on the forest floor C stocks. Estimating the loss of C stock in a short-term perspective requires measuring changes in soil respiration. This is not trivial due to the contribution of both soil microbes and vegetation to the measured CO2 flux. However, C stable isotopes can be used to partition the respiration and potentially to assess how much of the recalcitrant C stock in the forest floor is lost. Here, we measured the soil respiration at two forest sites where different regeneration methods were applied, along with an intact forest soil for reference. In so doing, we used a closed dynamic chamber for measuring respiration and the 13C composition of the emitted CO2. The chamber measurements were then supplemented with the soil organic carbon analysis and its δ13C content. The mean δ13C-CO2 estimates for the source of the CO2 were -26.4, -27.9 and -29.5‰, for the forest, unploughed and ploughed, respectively. The 13C of the soil organic carbon did, not differ significantly between sites. The higher soil respiration rate at the forest, as compared to the unploughed site, could be attributed to the autotrophic respiration by the forest floor vegetation.

Deep Soil Carbon Influenced Following Forest Organic Matter Manipulation In A Loblolly Pine Plantation In The Southeastern United States

NASA Astrophysics Data System (ADS)

Hatten, J. A.; Mack, J.; Sucre, E.; Leggett, Z.; Roberts, S.; Dewey, J.

2013-12-01

Forest harvest residues and forest floor materials are significant sources of mineral soil organic matter and nutrients for regenerating and establishing forests. Harvest residues in particular are occasionally removed, piled, or burned following harvesting. Weyerhaeuser Company established an experimental study to evaluate the effect of the removal and addition of harvest residual and forest-floor on site productivity and soil carbon. This study was installed in a loblolly pine plantation near Millport, Alabama, USA on the Upper Gulf Coastal Plain to test both extremes from complete removal of harvest residues and forest floor to doubling of these materials. This study has been continuously monitored since its establishment in 1994. We have examined the effects of varying forest floor levels on the biomass, soil carbon content, and soil carbon composition in the context of these management activities. Above- and below-ground productivity, soil moisture, soil temperature, and nutrient dynamics have been related to soil organic carbon in mineral soil, size/density fractionation, and lignin and cutin biomarkers from the cupric oxide (CuO)-oxidation technique. We have found that while removing litter and harvest residues has little effect on biomass production and soil carbon, importing litter and harvest residues increases forest productivity and soil carbon content. Interestingly, increased carbon was observed in all depths assessed (O horizon, 0-20, 20-40, and 40-60cm) suggesting that this practice may sequester organic carbon in deep soil horizons. Our biomarker analysis indicated that importing litter and harvest residues increased relative contributions from above ground sources at the 20-40cm depth and increased relative contributions from belowground sources at the 40-60cm depth. These results suggest that organic matter manipulations in managed forests can have significant effects on deep soil carbon that may be resistant to mineralization or the effects of other perturbations such as climate change.

Hydrogenotrophic methanogenesis is the dominant methanogenic pathway in neotropical tank bromeliad wetlands.

PubMed

Martinson, Guntars O; Pommerenke, Bianca; Brandt, Franziska B; Homeier, Jürgen; Burneo, Juan I; Conrad, Ralf

2018-02-01

Several thousands of tank bromeliads per hectare of neotropical forest create a unique wetland ecosystem that emits substantial amounts of CH 4 . Tank bromeliads growing in the forest canopy (functional type-II tank bromeliads) were found to emit more CH 4 than tank bromeliads growing on the forest floor (functional type-I tank bromeliads) but the reasons for this difference and the underlying microbial CH 4 -cycling processes have not been studied. Therefore, we characterized archaeal communities in bromeliad tanks of the two different functional types in a neotropical montane forest of southern Ecuador using terminal-restriction fragment length polymorphism (T-RFLP) and performed tank-slurry incubations to measure CH 4 production potential, stable carbon isotope fractionation and pathway of CH 4 formation. The archaeal community composition was dominated by methanogens and differed between bromeliad functional types. Hydrogenotrophic Methanomicrobiales were the dominant methanogens and hydrogenotrophic methanogenesis was the dominant methanogenic pathway among all bromeliads. The relative abundance of aceticlastic Methanosaetaceae and the relative contribution of aceticlastic methanogenesis increased in type-I tank bromeliads probably due to more oxic conditions in type-I than in type-II bromeliads leading to the previously observed lower in situ CH 4 emissions from type-I tank bromeliads but to higher CH 4 production potentials in type-I tank bromeliad slurries. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

Effects of exotic plantation forests on soil edaphon and organic matter fractions.

PubMed

Xu, Gang; Liu, Yao; Long, Zhijian; Hu, Shanglian; Zhang, Yuanbin; Jiang, Hao

2018-06-01

There is uncertainty and limited knowledge regarding soil microbial properties and organic matter fractions of natural secondary forest accompanying chemical environmental changes of replacement by pure alien plantation forests in a hilly area of southwest of Sichuan province China. The aim of this study was to evaluate the impact of natural secondary forest (NSF) to pure Cryptomeria fortunei forest (CFF) and Cunninghamia lanceolata forest (CLF) on soil organic fractions and microbial communities. The results showed that the soil total phospholipid fatty acids (PLFAs), total bacteria and fungi, microbial carbon pool, organic recalcitrant carbon (C) and (N) fractions, soil microbial quotient and labile and recalcitrant C use efficiencies in each pure plantation were significantly decreased, but their microbial N pool, labile C and N pools, soil carbon dioxide efflux, soil respiratory quotient and recalcitrant N use efficiency were increased. An RDA analysis revealed that soil total PLFAs, total bacteria and fungi and total Gram-positive and Gram-negative bacteria were significantly associated with exchangeable Al 3+ , exchangeable acid, Al 3+ , available P and Mg 2+ and pH, which resulted into microbial functional changes of soil labile and recalcitrant substrate use efficiencies. Modified microbial C- and N-use efficiency due to forest conversion ultimately meets those of rapidly growing trees in plantation forests. Enlarged soil labile fractions and soil respiratory quotients in plantation forests would be a potential positive effect for C source in the future forest management. Altogether, pure plantation practices could provoke regulatory networks and functions of soil microbes and enzyme activities, consequently leading to differentiated utilization of soil organic matter fractions accompanying the change in environmental factors. Copyright © 2018 Elsevier B.V. All rights reserved.

Eco-hydrological Controls on Litter Moisture Dynamics in Complex Terrain: Implications for Fuel Moisture and Fire Regimes in Temperate Forests

NASA Astrophysics Data System (ADS)

Nyman, P.; Duff, T. J.; Sheridan, G. J.

2016-12-01

Moisture content in litter on the forest floor can control ignition and spread of forest fires. The micrometeorological factors driving variation in litter moisture at the landscape scale are poorly understood, particularly in areas with heterogeneous vegetation and complex terrain. In this research we seek to quantify how climate, vegetation and eco-hydrological feedbacks contribute to variation in net radiation and potential evaporation at the forest floor. Research sites were established at 12 locations in southeast Australia with variable precipitation, solar exposure, and drainage areas. Forests ranged from open woodland to tall temperate forests. We measured solar radiation, air temperature, relative humidity, litter moisture, soil moisture, and litter temperature. Forest structure was characterised using hemispherical photos and LIDAR. Using these data on microclimate and vegetation structure we parameterise a model of daily potential evaporation at the forest floor. Results show that variation in evaporation rates from litter is driven by net radiation and the role of vapour pressure deficit is almost negligible due to high aerodynamic resistance. In open woodlands the net radiation is directly related to short-wave radiation and evaporation remains high despite low temperatures. In the tall wet forests, commonly found along drainage lines and on slopes with polar-facing aspects, the long-wave radiation was just as important as the shortwave radiation. Air temperature is therefore important in determining the flammability of these more productive forests. By implication, in complex terrain with heterogeneous forests, the temperature in the wet parts of the landscape is important in controlling connectivity of fuels and large-scale fire activity.

Observational scores of dampness and mold associated with measurements of microbial agents and moisture in three public schools

PubMed Central

Cho, S. J.; Cox-Ganser, J. M.; Park, J.-H.

2015-01-01

We examined associations between observational dampness scores and measurements of microbial agents and moisture in three public schools. A dampness score was created for each room from 4-point-scale scores (0–3) of water damage, water stains, visible mold, moldy odor, and wetness for each of 8 room components (ceiling, walls, windows, floor, ventilation, furniture, floor trench, and pipes), when present. We created mixed microbial exposure indices (MMEIs) for each of 121 rooms by summing decile ranks of 8 analytes (total culturable fungi; total, Gram-negative, and Gram-positive culturable bacteria; ergosterol; (1→3)-β-D-glucan; muramic acid; and endotoxin) in floor dust. We found significant (P ≤ 0.01) linear associations between the dampness score and culturable bacteria (total, Gram-positive, and Gram-negative) and the MMEIs. Rooms with dampness scores greater than 0.25 (median) had significantly (P < 0.05) higher levels of most microbial agents, MMEIs, and relative moisture content than those with lower scores (≤0.25). Rooms with reported recent water leaks had significantly (P < 0.05) higher dampness scores than those with historical or no reported water leaks. This study suggests that observational assessment of dampness and mold using a standardized form may be valuable for identifying and documenting water damage and associated microbial contamination. PMID:25650175

The Function of the Superficial Root Mat in the Biogeochemical Cycles of Nutrients in Congolese Eucalyptus Plantations

PubMed Central

LACLAU, JEAN‐PAUL; TOUTAIN, FRANÇOIS; M’BOU, ARMEL THONGO; ARNAUD, MICHEL; JOFFRE, RICHARD; RANGER, JACQUES

2004-01-01

• Background and Aims The importance of superficial root mats inside the forest floor for the nutrition of Amazonian rain forests has been extensively investigated. The present study was aimed at assessing the function of a root mat adherent to decomposing organic material observed in Eucalyptus plantations. • Methods The development of the root mat was studied through micromorphological observations of thin litter sections, and the influence of soil microtopography and soil water repellency on root mat biomass was assessed in situ on an area of 5 m2. In addition, input–output budgets of nutrients within the forest floor were established from measurements of litterfall, dissolved nutrients in gravitational solutions, and forest floor nutrient contents. • Key Findings The amounts of nutrients released during litter decay in this ecosystem during the period of study were, on average, 46, 3, 4, 19 and 17 kg ha–1 year–1 for N, P, K, Ca and Mg, respectively. The simultaneous measurements of the chemical composition of throughfall solutions and leachates beneath the forest floor showed a very quick uptake of nutrients by the root mat during the decomposition processes. Indeed, the solutions did not become noticeably enriched in nutrients during their passage through the holorganic layer, despite large amounts of elements being released during litter decay. The root mat biomass decreased significantly during the dry season, and a preferential development in microdepressions at the soil surface was observed. A strong water repellency observed in these depressions might enhance the ability of the roots to take up water and nutrients during the dry periods. • Conclusions The root mat was active throughout the year to catch the flux of nutrients from the biodegradation of the forest floor, preventing the transfer of dissolved nutrients toward deeper soil horizons. This mechanism is involved in the successful adaptation of this Eucalyptus hybrid in areas covered by ‘climacic’ savannas in Congo. PMID:14749252

Calcium oxalate contribution to calcium cycling in forests of contrasting nutrient status

USGS Publications Warehouse

Dauer, Jenny M.; Perakis, Steven S.

2014-01-01

Calcium oxalate (Ca oxalate) is an insoluble biomineral that forms in plants and fungi, and occurs in soils across many types of ecosystems. Assessing how Ca oxalate may shape ecosystem Ca cycling requires information on the distribution of Ca oxalate among plant biomass, detritus, and mineral soil, and how it varies with ecosystem Ca status. We compared two Douglas-fir forests of contrasting ecosystem Ca availability, and found that Ca oxalate was partitioned similarly among plant biomass, detritus and mineral soil major ecosystem compartments at both sites, and total pools of Ca oxalate were greater in the high-Ca forest. However, the proportional importance of Ca oxalate was greater in the low-Ca than high-Ca forest (18% versus 4% of actively cycling ecosystem Ca, respectively). And calcium oxalate in mineral soil, which is of particular interest as a potential long-term Ca reservoir, was a larger portion of total available Ca (exchangeable Ca plus Ca oxalate Ca) in the low-Ca site than the high-Ca site (9% versus 1% of available soil Ca, respectively). Calcium oxalate was the dominant form of Ca returned from plants to soil as leaf litterfall at the high-Ca site, yet calcium oxalate disappeared rapidly from decomposing litter (0.28 yr−1 or faster) at both sites. We conclude that accumulation of Ca oxalate in forest ecosystems appears most closely related to overall Ca supply for live biomass pools, and that the accumulation of Ca oxalate in forest floor and mineral soil is limited by rapid microbial degradation of putatively unavailable Ca oxalate.

Forest soil microbial communities: Using metagenomic approaches to survey permanent plots

Treesearch

Amy L. Ross-Davis; Jane E. Stewart; John W. Hanna; John D. Shaw; Andrew T. Hudak; Theresa B. Jain; Robert J. Denner; Russell T. Graham; Deborah S. Page-Dumroese; Joanne M. Tirocke; Mee-Sook Kim; Ned B. Klopfenstein

2014-01-01

Forest soil ecosystems include some of the most complex microbial communities on Earth (Fierer et al. 2012). These assemblages of archaea, bacteria, fungi, and protists play essential roles in biogeochemical cycles (van der Heijden et al. 2008) and account for considerable terrestrial biomass (Nielsen et al. 2011). Yet, determining the microbial composition of forest...

Estimation of Moisture Content of Forest Canopy and Floor from SAR Data Part I: Volume Scattering Case

NASA Technical Reports Server (NTRS)

Moghaddam, M.; Saatchi, S.

1996-01-01

To understand and predict the functioning of forest biomes, their interaction with the atmosphere, and their growth rates, the knowledge of moisture content of their canopy and the floor soil is essential. The synthetic aperture radar on airborne and spaceborne platforms has proven to be a flexible tool for measuring electromagnetic back- scattering properties of vegetation related to their moisture content.

Whole-tree and forest floor removal from a loblolly pine plantation have no effect on forest floor CO2 efflux 10 years after harvest

Treesearch

John R. Butnor; Kurt H. Johnsen; Felipe G. Sanchez

2006-01-01

Intensive management of southern pine plantations has yielded multifold increases in productivity over the last half century. The process of harvesting merchantable material and preparing a site for planting can lead to a considerable loss of organic matter. Intensively managed stands may experience more frequent disturbance as rotations decrease in length, exposing...

Shifts in Aboveground and Forest Floor Carbon and Nitrogen Pools After Felling and Burning in the Southern Appalachians

Treesearch

Barton D. Clinton; James M. Vose; Wayne T. Swank

1996-01-01

Changes in aboveground and forest floor mass, carbon (C), and nitrogen (N) pools were quantified on three sites in the southern Appalachians 2 yr after felling and burning. Before felling and burning, stands were characterized by sparse overstories and dense Kalmia latifolia L. understories. Two years after burning, foliar C and N pools had reached 25% and 29% of...

Soil microbial diversity, site conditions, shelter forest land, saline water drip-irrigation, drift desert.

PubMed

Jin, Zhengzhong; Lei, Jiaqiang; Li, Shengyu; Xu, Xinwen

2013-10-01

Soil microbes in forest land are crucial to soil development in extreme areas. In this study, methods of conventional culture, PLFA and PCR-DGGE were utilized to analyze soil microbial quantity, fatty acids and microbial DNA segments of soils subjected to different site conditions in the Tarim Desert Highway forest land. The main results were as follows: the soil microbial amount, diversity indexes of fatty acid and DNA segment differed significantly among sites with different conditions (F < F0.05 ). Specifically, the values were higher in the middle and base of dunes than the top part of dunes and hardened flat sand, but all values for dunes were higher than for drift sand. Bacteria was dominant in the soil microbial community (>84%), followed by actinomycetes and then fungi (<0.05%). Vertical differences in the soil microbial diversity were insignificant at 0-35 cm. Correlation analysis indicated that the forest trees grew better as the soil microbial diversity index increased. Therefore, construction of the Tarim Desert Highway shelter-forest promoted soil biological development; however, for enhancing sand control efficiency and promoting sand development, we should consider the effects of site condition in the construction and regeneration of shelter-forest ecological projects. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tree species and soil nutrient profiles in old-growth forests of the Oregon Coast Range

USGS Publications Warehouse

Cross, Alison; Perakis, Steven S.

2011-01-01

Old-growth forests of the Pacific Northwest provide a unique opportunity to examine tree species – soil relationships in ecosystems that have developed without significant human disturbance. We characterized foliage, forest floor, and mineral soil nutrients associated with four canopy tree species (Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco), western hemlock (Tsuga heterophylla (Raf.) Sarg.), western redcedar (Thuja plicata Donn ex D. Don), and bigleaf maple (Acer macrophyllum Pursh)) in eight old-growth forests of the Oregon Coast Range. The greatest forest floor accumulations of C, N, P, Ca, Mg, and K occurred under Douglas-fir, primarily due to greater forest floor mass. In mineral soil, western hemlock exhibited significantly lower Ca concentration and sum of cations (Ca + Mg + K) than bigleaf maple, with intermediate values for Douglas-fir and western redcedar. Bigleaf maple explained most species-based differences in foliar nutrients, displaying high concentrations of N, P, Ca, Mg, and K. Foliar P and N:P variations largely reflected soil P variation across sites. The four tree species that we examined exhibited a number of individualistic effects on soil nutrient levels that contribute to biogeochemical heterogeneity in these ecosystems. Where fire suppression and long-term succession favor dominance by highly shade-tolerant western hemlock, our results suggest a potential for declines in both soil Ca availability and soil biogeochemical heterogeneity in old-growth forests.

Priming alters soil carbon dynamics during forest succession

NASA Astrophysics Data System (ADS)

Qiao, Na; Xu, Xingliang; Wang, Juan; Kuzyakov, Yakov

2017-04-01

The mechanisms underlying soil carbon (C) dynamics during forest succession remain challenged. We examined priming of soil organic matter (SOM) decomposition along a vegetation succession: grassland, young and old-growth forests. Soil C was primed much more strongly in young secondary forest than in grassland or old-growth forest. Priming resulted in large C losses (negative net C balance) in young-forest soil, whereas C stocks increased in grassland and old-growth forest. Microbial composition assessed by phospholipid fatty acids (PLFA) and utilization of easily available organics (13C-PLFA) indicate that fungi were responsible for priming in young-forest soils. Consequently, labile C inputs released by litter decomposition and root exudation determine microbial functional groups that decompose SOM during forest succession. These findings provide novel insights into connections between SOM dynamics and stabilization with microbial functioning during forest succession and show that priming is an important mechanism for contrasting soil C dynamics in young and old-growth forests.

Light accelerates plant responses to warming.

PubMed

De Frenne, Pieter; Rodríguez-Sánchez, Francisco; De Schrijver, An; Coomes, David A; Hermy, Martin; Vangansbeke, Pieter; Verheyen, Kris

2015-08-17

Competition for light has profound effects on plant performance in virtually all terrestrial ecosystems. Nowhere is this more evident than in forests, where trees create environmental heterogeneity that shapes the dynamics of forest-floor communities(1-3). Observational evidence suggests that biotic responses to both anthropogenic global warming and nitrogen pollution may be attenuated by the shading effects of trees and shrubs(4-9). Here we show experimentally that tree shade is slowing down changes in below-canopy communities due to warming. We manipulated levels of photosynthetically active radiation, temperature and nitrogen, alone and in combination, in a temperate forest understorey over a 3-year period, and monitored the composition of the understorey community. Light addition, but not nitrogen enrichment, accelerated directional plant community responses to warming, increasing the dominance of warmth-preferring taxa over cold-tolerant plants (a process described as thermophilization(6,10-12)). Tall, competitive plants took greatest advantage of the combination of elevated temperature and light. Warming of the forest floor did not result in strong community thermophilization unless light was also increased. Our findings suggest that the maintenance of locally closed canopy conditions could reduce, at least temporarily, warming-induced changes in forest floor plant communities.

Bryophyte species associations with coarse woody debris and stand ages in Oregon

USGS Publications Warehouse

Rambo, T.; Muir, Patricia S.

1998-01-01

We quantified the relationships of 93 forest floor bryophyte species, including epiphytes from incorporated litterfall, to substrate and stand age in Pseudotsuga menziesii-Tsuga heterophylla stands at two sites in western Oregon. We used the method of Dufrêne and Legendre that combines a species' relative abundance and relative frequency, to calculate that species' importance in relation to environmental variables. The resulting "indicator value" describes a species' reliability for indicating the given environmental parameter. Thirty-nine species were indicative of either humus, a decay class of coarse woody debris, or stand age. Bryophyte community composition changed along the continuum of coarse woody debris decomposition from recently fallen trees with intact bark to forest floor humus. Richness of forest floor bryophytes will be enhanced when a full range of coarse woody debris decay classes is present. A suite of bryophytes indicated old-growth forest. These were mainly either epiphytes associated with older conifers or liverworts associated with coarse woody debris. Hardwood-associated epiphytes mainly indicated young stands. Mature conifers, hardwoods, and coarse woody debris are biological legacies that can be protected when thinning managed stands to foster habitat complexity and biodiversity, consistent with an ecosystem approach to forest management.

Severe soil frost reduced losses of carbon and nitrogen from the forest floor during simulated snowmelt: A laboratory experiment

Treesearch

Andrew B. Reinmann; Pamela H. Templer; John L. Campbell

2012-01-01

Considerable progress has been made in understanding the impacts of soil frost on carbon (C) and nitrogen (N) cycling, but the effects of soil frost on C and N fluxes during snowmelt remain poorly understood. We conducted a laboratory experiment to determine the effects of soil frost on C and N fluxes from forest floor soils during snowmelt. Soil cores were collected...

Forest structure and downed woody debris in boreal, temperate, and tropical forest fragments.

PubMed

Gould, William A; González, Grizelle; Hudak, Andrew T; Hollingsworth, Teresa Nettleton; Hollingsworth, Jamie

2008-12-01

Forest fragmentation affects the heterogeneity of accumulated fuels by increasing the diversity of forest types and by increasing forest edges. This heterogeneity has implications in how we manage fuels, fire, and forests. Understanding the relative importance of fragmentation on woody biomass within a single climatic regime, and along climatic gradients, will improve our ability to manage forest fuels and predict fire behavior. In this study we assessed forest fuel characteristics in stands of differing moisture, i.e., dry and moist forests, structure, i.e., open canopy (typically younger) vs. closed canopy (typically older) stands, and size, i.e., small (10-14 ha), medium (33 to 60 ha), and large (100-240 ha) along a climatic gradient of boreal, temperate, and tropical forests. We measured duff, litter, fine and coarse woody debris, standing dead, and live biomass in a series of plots along a transect from outside the forest edge to the fragment interior. The goal was to determine how forest structure and fuel characteristics varied along this transect and whether this variation differed with temperature, moisture, structure, and fragment size. We found nonlinear relationships of coarse woody debris, fine woody debris, standing dead and live tree biomass with mean annual median temperature. Biomass for these variables was greatest in temperate sites. Forest floor fuels (duff and litter) had a linear relationship with temperature and biomass was greatest in boreal sites. In a five-way multivariate analysis of variance we found that temperature, moisture, and age/structure had significant effects on forest floor fuels, downed woody debris, and live tree biomass. Fragment size had an effect on forest floor fuels and live tree biomass. Distance from forest edge had significant effects for only a few subgroups sampled. With some exceptions edges were not distinguishable from interiors in terms of fuels.

Viability of forest floor and canopy seed banks in Pinus contorta var. latifolia (Pinaceae) forests after a mountain pine beetle outbreak.

PubMed

Teste, François P; Lieffers, Victor J; Landhäusser, Simon M

2011-04-01

Seed banks are important for the natural regeneration of many forest species. Most of the seed bank of serotinous lodgepole pine is found in the canopy, but after an outbreak of mountain pine beetle (MPB), a considerable forest-floor seed bank develops through the falling of canopy cones. After large-scale mortality of pine stands from MPB, however, the viability of seeds in both the canopy and the forest-floor cone bank is uncertain. We sampled cones in five stands 3 yr after MPB (3y-MPB); five stands 6 yr after MPB (6y-MPB); and 10 stands 9 yr after MPB (9y-MPB), in central British Columbia, Canada. Seeds were extracted and viability tested using germination techniques. Forest-floor cones had seed with high germination capacity (GC): 82% for embedded (partly buried) closed cones vs. 45% for buried partly open cones. For canopy cones, GC steeply declined about 15 yr after cone maturation and by 25 yr, GC was 50%, compared with 98% in the first year. In the 3y- and 6y-MPB stands, seeds from cones that were 7 to 9 yr old had similar GC on dead and living trees; however, seeds from the dead trees had lower vigor than seeds from living trees. We demonstrate for the first time that a serotinous pine can form a viable soil seed bank by cone burial, which may facilitate natural regeneration if a secondary disturbance occurs. Seeds contained in 15-yr-old cones showed a steep decline in viability, which could limit regeneration if there is a long delay before a secondary disturbance.

Carbon stocks of three secondary coniferous forests along an altitudinal gradient on Loess Plateau in inland China

PubMed Central

Liu, Ning; Nan, Hongwei

2018-01-01

Natural forests in inland China are generally distributed in montane area and secondary due to a semi-arid climate and past anthropogenic disturbances. However, quantification of carbon (C) stock in these forests and the role of altitude in determining C storage and its partition among ecosystem components are unclear. We sampled 54 stands of three secondary coniferous forests (Larix principis-rupprechtii (LP) forest, Picea meyerii (PM) forest and Pinus tabulaeformis (PT) forest) on Loess Plateau in an altitudinal range of 1200-2700m a.s.l. C stocks of tree layer, shrub layer, herb layer, coarse wood debris, forest floor and soil were estimated. We found these forests had relatively high total C stocks. Driven by both higher vegetation and soil C stocks, total C stocks of LP and PM forests in the high altitudinal range were 375.0 and 368.4 t C ha-1 respectively, significantly higher than that of PT forest in the low altitudinal range (230.2 t C ha-1). In addition, understory shrubs accounted for about 20% of total biomass in PT forest. The proportions of vegetation to total C stock were similar among in the three forests (below 45%), so were the proportions of soil C stock (over 54%). Necromass C stocks were also similar among these forests, but their proportions to total C stock were significantly lower in LP and PM forests (1.4% and 1.6%) than in PT forest (3.0%). Across forest types, vegetation biomass and soil C stock simultaneously increased with increasing altitude, causing fairly unchanged C partitioning among ecosystem components along the altitudinal gradient. Soil C stock also increased with altitude in LP and PT forests. Forest floor necromass decreased with increasing altitude across the three forests. Our results suggest the important role of the altitudinal gradient in C sequestration and floor necromass of these three forests in terms of alleviated water conditions and in soil C storage of LP and PM forests in terms of temperature change. PMID:29723254

Bacterial diversity of floor drain biofilms and drain waters in a Listeria monocytogenes contaminated food processing environment.

PubMed

Dzieciol, Monika; Schornsteiner, Elisa; Muhterem-Uyar, Meryem; Stessl, Beatrix; Wagner, Martin; Schmitz-Esser, Stephan

2016-04-16

Sanitation protocols are applied on a daily basis in food processing facilities to prevent the risk of cross-contamination with spoilage organisms. Floor drain water serves along with product-associated samples (slicer dust, brine or cheese smear) as an important hygiene indicator in monitoring Listeria monocytogenes in food processing facilities. Microbial communities of floor drains are representative for each processing area and are influenced to a large degree by food residues, liquid effluents and washing water. The microbial communities of drain water are steadily changing, whereas drain biofilms provide more stable niches. Bacterial communities of four floor drains were characterized using 16S rRNA gene pyrosequencing to better understand the composition and exchange of drain water and drain biofilm communities. Furthermore, the L. monocytogenes contamination status of each floor drain was determined by applying cultivation-independent real-time PCR quantification and cultivation-dependent detection according to ISO11290-1. Pyrosequencing of 16S rRNA genes of drain water and drain biofilm bacterial communities yielded 50,611 reads, which were clustered into 641 operational taxonomic units (OTUs), affiliated to 16 phyla dominated by Proteobacteria, Firmicutes and Bacteroidetes. The most abundant OTUs represented either product- (Lactococcus lactis) or fermentation- and food spoilage-associated phylotypes (Pseudomonas mucidolens, Pseudomonas fragi, Leuconostoc citreum, and Acetobacter tropicalis). The microbial communities in DW and DB samples were distinct in each sample type and throughout the whole processing plant, indicating the presence of indigenous specific microbial communities in each processing compartment. The microbiota of drain biofilms was largely different from the microbiota of the drain water. A sampling approach based on drain water alone may thus only provide reliable information on planktonic bacterial cells but might not allow conclusions on the bacterial composition of the microbiota in biofilms. Copyright © 2016. Published by Elsevier B.V.

Observational scores of dampness and mold associated with measurements of microbial agents and moisture in three public schools.

PubMed

Cho, S J; Cox-Ganser, J M; Park, J-H

2016-04-01

We examined associations between observational dampness scores and measurements of microbial agents and moisture in three public schools. A dampness score was created for each room from 4-point-scale scores (0-3) of water damage, water stains, visible mold, moldy odor, and wetness for each of 8 room components (ceiling, walls, windows, floor, ventilation, furniture, floor trench, and pipes), when present. We created mixed microbial exposure indices (MMEIs) for each of 121 rooms by summing decile ranks of 8 analytes (total culturable fungi; total, Gram-negative, and Gram-positive culturable bacteria; ergosterol; (1→3)-β-D-glucan; muramic acid; and endotoxin) in floor dust. We found significant (P ≤ 0.01) linear associations between the dampness score and culturable bacteria (total, Gram-positive, and Gram-negative) and the MMEIs. Rooms with dampness scores greater than 0.25 (median) had significantly (P < 0.05) higher levels of most microbial agents, MMEIs, and relative moisture content than those with lower scores (≤0.25). Rooms with reported recent water leaks had significantly (P < 0.05) higher dampness scores than those with historical or no reported water leaks. This study suggests that observational assessment of dampness and mold using a standardized form may be valuable for identifying and documenting water damage and associated microbial contamination. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Soil mineralogy and microbes determine forest life history strategy and carbon cycling in humid tropical forests

NASA Astrophysics Data System (ADS)

Soong, J.; Verbruggen, E.; Peñuelas, J.; Janssens, I. A.; Grau, O.

2017-12-01

Tropical forests account for over one third of global terrestrial gross primary productivity and cycle more C than any other ecosystem on Earth. However, we still lack a mechanistic understanding of how such high productivity is maintained on the old, highly weathered and phosphorus depleted soils in the tropics. We hypothesized that heterogeneity in soil texture, mineralogy and microbial community composition may be the major drivers of differences in soil C storage and P limitation across tropical forests. We sampled 12 forest sites across a 200 km transect in the humid neo-tropics of French Guiana that varied in soil texture, precipitation and mineralogy. We found that soil texture was a major driver of soil carbon stocks and forest life history strategy, where sandy forests have lower soil C stocks, slower turnover and decomposition and a more closed nutrient cycle while clayey forests have higher soil C stocks, faster turnover and a more leaky nutrient cycle (using natural abundance stable isotope evidence). We found that although the presence of Al and Fe oxides in the clayey soils occludes soil organic matter and P, a greater abundance of arbuscular mycorrhizal fungi help forests to access occluded P in clayey soils fueling higher turnover and faster decomposition rates. Evidence from a laboratory incubation of tropical soils with nutrient additions further demonstrates the de-coupling of microbial P demands from C:N limitations providing further evidence for the need to examine microbial stoichiometry to explain C cycling in the P-limited tropics. We argue that microbial community composition and physiological demands, constrained within the limitations of soil mineralogical reactivity, largely controls nutrient and C cycling in tropical forest soils. Together our observational field study and laboratory incubation provide a unique dataset to shed light on the mineralogical and microbial controls on C and nutrient cycling in tropical soils. By integrating microbial, soil, litter and forest metrics we describe how microbes, minerals and soil organic matter act as an ecosystem property driving forest dynamics via microbial and plant stoichiometric constraints.

Propagation of noise over and through a forest stand

Treesearch

Lee P. Herrington; C. Brock

1977-01-01

Measurements of the two-dimensional acoustic field in a forest resulting from a source located outside the forest indicated that the attenuation pattern near the ground is significantly different from the pattern higher up in the forest. The patterns of attenuation support the recent theory that the forest floor is the main absorber of acoustic energy in the forest....

Plant community influence on soil microbial response after a wildfire in Sierra Nevada National Park (Spain).

PubMed

Bárcenas-Moreno, Gema; García-Orenes, Fuensanta; Mataix-Solera, Jorge; Mataix-Beneyto, Jorge

2016-12-15

Plant community influence on microbial response after fire has been studied in a Sierra Nevada National Park area affected by a wildfire in 2005. Two different plant communities adapted to different altitudes were selected to analyse possible differences on soil microbial recolonisation process after fire, in oak forest and high mountain shrub communities. Microbial abundance, activity and community composition were monitored to evaluate medium-term changes. Microbial abundance was studied by mean of microbial biomass carbon and plate count methods; microbial activity was analysed by microbial respiration and bacterial growth while microbial community composition was determined by analysing phospholipid fatty acid pattern. Under unburnt conditions oak forest showed higher nutrient content, pH and microbial abundance and activity values than the high mountain shrubs community. Different parameters studied showed different trends with time, highlighting important changes in microbial community composition in high mountain shrubs from first sampling to the second one. Post-fire recolonisation process was different depending on plant community studied. Highlighting fungal response and microbial activity were stimulated in burnt high mountain shrubs community whilst it was negatively affected in oak forest. Fire induced changes in oak forest were almost neutralized 20months after the fire, while high mountain shrubs community still showed fire-induced changes at the end of the study. Copyright © 2016 Elsevier B.V. All rights reserved.

Forest soil carbon is threatened by intensive biomass harvesting.

PubMed

Achat, David L; Fortin, Mathieu; Landmann, Guy; Ringeval, Bruno; Augusto, Laurent

2015-11-04

Forests play a key role in the carbon cycle as they store huge quantities of organic carbon, most of which is stored in soils, with a smaller part being held in vegetation. While the carbon storage capacity of forests is influenced by forestry, the long-term impacts of forest managers' decisions on soil organic carbon (SOC) remain unclear. Using a meta-analysis approach, we showed that conventional biomass harvests preserved the SOC of forests, unlike intensive harvests where logging residues were harvested to produce fuelwood. Conventional harvests caused a decrease in carbon storage in the forest floor, but when the whole soil profile was taken into account, we found that this loss in the forest floor was compensated by an accumulation of SOC in deeper soil layers. Conversely, we found that intensive harvests led to SOC losses in all layers of forest soils. We assessed the potential impact of intensive harvests on the carbon budget, focusing on managed European forests. Estimated carbon losses from forest soils suggested that intensive biomass harvests could constitute an important source of carbon transfer from forests to the atmosphere (142-497 Tg-C), partly neutralizing the role of a carbon sink played by forest soils.

Effects of nitrogen and phosphorus additions on soil microbial biomass and community structure in two reforested tropical forests.

PubMed

Liu, Lei; Gundersen, Per; Zhang, Wei; Zhang, Tao; Chen, Hao; Mo, Jiangming

2015-09-23

Elevated nitrogen (N) deposition may aggravate phosphorus (P) deficiency in forests in the warm humid regions of China. To our knowledge, the interactive effects of long-term N deposition and P availability on soil microorganisms in tropical replanted forests remain unclear. We conducted an N and P manipulation experiment with four treatments: control, N addition (15 g N m(-2)·yr(-1)), P addition (15 g P m(-2)·yr(-1)), and N and P addition (15 + 15 g N and P m(-2)·yr(-1), respectively) in disturbed (planted pine forest with recent harvests of understory vegetation and litter) and rehabilitated (planted with pine, but mixed with broadleaf returning by natural succession) forests in southern China. Nitrogen addition did not significantly affect soil microbial biomass, but significantly decreased the abundance of gram-negative bacteria PLFAs in both forest types. Microbial biomass increased significantly after P addition in the disturbed forest but not in the rehabilitated forest. No interactions between N and P additions on soil microorganisms were observed in either forest type. Our results suggest that microbial growth in replanted forests of southern China may be limited by P rather than by N, and this P limitation may be greater in disturbed forests.

Estimating forest floor fuels in eastern U.S. forests

Treesearch

David C. Chojnacky; Steven G. McNulty; Jennifer Moore Myers; Michael K. Gavazzi

2005-01-01

The Forest Inventory Analysis (FIA) program (U.S. Department of Agriculture, Forest Service) systematically samples the nation's forests and currently measures variable related to down woody material (DWM) on a subsample of its plots in the third phase of a 3-phase sampling design. This paper focuses on: (1) compiling estimates of DWM within limitations of...

Small mammals in managed, naturally young, and old-growth forests.

Treesearch

A.B. Carey; M.L. Johnson

1995-01-01

Forest managers in the Pacific Northwest are faced with new challenges of providing for all wildlife in managed forests. Our objective was to elucidate the factors governing the composition and biomass of forest floor mammal communities that are amenable to management. We sampled small mammal communities in forests of various management histories on the Olympic...

The Role of Soil Organic Matter, Nutrients, and Microbial Community Structure on the Performance of Microbial Fuel Cells

NASA Astrophysics Data System (ADS)

Rooney-Varga, J. N.; Dunaj, S. J.; Vallino, J. J.; Hines, M. E.; Gay, M.; Kobyljanec, C.

2011-12-01

Microbial fuel cells (MFCs) offer the potential for generating electricity, mitigating greenhouse gas emissions, and bioremediating pollutants through utilization of a plentiful, natural, and renewable resource: soil organic carbon. In the current study, we analyzed microbial community structure, MFC performance, and soil characteristics in different microhabitats (bulk soil, anode, and cathode) within MFCs constructed from agricultural or forest soils in order to determine how soil type and microbial dynamics influence MFC performance. MFCs were constructed with soils from agricultural and hardwood forest sites at Harvard Forest (Petersham, MA). The bulk soil characteristics were analyzed, including polyphenols, short chain fatty acids, total organic C and N, abiotic macronutrients, N and P mineralization rates, CO2 respiration rates, and MFC power output. Microbial community structure of the anodes, cathodes, and bulk soils was determined with molecular fingerprinting methods, which included terminal restriction length polymorphism (T-RFLP) analysis and 16S rRNA gene sequencing analysis. Our results indicated that MFCs constructed from agricultural soil had power output about 17 times that of forest soil-based MFCs and respiration rates about 10 times higher than forest soil MFCs. Agricultural soil MFCs had lower C:N ratios, polyphenol content, and acetate concentrations than forest soil MFCs, suggesting that active agricultural MFC microbial communities were supported by higher quality organic carbon. Microbial community profile data indicate that the microbial communities at the anode of the high power MFCs were less diverse than in low power MFCs and were dominated by Deltaproteobacteria, Geobacter, and, to a lesser extent, Clostridia, while low-power MFC anode communities were dominated by Clostridia. These data suggest that the presence of organic carbon substrate (acetate) was not the major limiting factor in selecting for highly electrogenic microbial communities, while the quality of available organic matter may have played a significant role in supporting high performing microbial communities.

A Newly Identified Role of the Deciduous Forest Floor in the Timing of Green-Up

NASA Astrophysics Data System (ADS)

Lapenis, Andrei G.; Lawrence, Gregory B.; Buyantuev, Alexander; Jiang, Shiguo; Sullivan, Timothy J.; McDonnell, Todd C.; Bailey, Scott

2017-11-01

Plant phenology studies rarely consider controlling factors other than air temperature. We evaluate here the potential significance of physical and chemical properties of soil (edaphic factors) as additional important controls on phenology. More specifically, we investigate causal connections between satellite-observed green-up dates of small forest watersheds and soil properties in the Adirondack Mountains of New York, USA. Contrary to the findings of previous studies, where edaphic controls of spring phenology were found to be marginal, our analyses show that at least three factors manifest themselves as significant controls of seasonal patterns of variation in vegetated land surfaces observed from remote sensing: (1) thickness of the forest floor, (2) concentration of exchangeable soil potassium, and (3) soil acidity. For example, a thick forest floor appears to delay the onset of green-up. Watersheds with elevated concentrations of potassium are associated with early surface greening. We also found that trees growing in strongly acidified watersheds demonstrate delayed green-up dates. Overall, our work demonstrates that, at the scale of small forest watersheds, edaphic factors can explain a significant percentage of the observed spatial variation in land surface phenology that is comparable to the percentage that can be explained by climatic and landscape factors. We conclude that physical and chemical properties of forest soil play important roles in forest ecosystems as modulators of climatic drivers controlling the rate of spring soil warming and the transition of trees out of winter dormancy.

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.

Parameterized isoprene and monoterpene emissions from the boreal forest floor: Implementation into a 1D chemistry-transport model and investigation of the influence on atmospheric chemistry

NASA Astrophysics Data System (ADS)

Mogensen, Ditte; Aaltonen, Hermanni; Aalto, Juho; Bäck, Jaana; Kieloaho, Antti-Jussi; Gierens, Rosa; Smolander, Sampo; Kulmala, Markku; Boy, Michael

2015-04-01

Volatile organic compounds (VOCs) are emitted from the biosphere and can work as precursor gases for aerosol particles that can affect the climate (e.g. Makkonen et al., ACP, 2012). VOC emissions from needles and leaves have gained the most attention, however other parts of the ecosystem also have the ability to emit a vast amount of VOCs. This, often neglected, source can be important e.g. at periods where leaves are absent. Both sources and drivers related to forest floor emission of VOCs are currently limited. It is thought that the sources are mainly due to degradation of organic matter (Isidorov and Jdanova, Chemosphere, 2002), living roots (Asensio et al., Soil Biol. Biochem., 2008) and ground vegetation. The drivers are biotic (e.g. microbes) and abiotic (e.g. temperature and moisture). However, the relative importance of the sources and the drivers individually are currently poorly understood. Further, the relative importance of these factors is highly dependent on the tree species occupying the area of interest. The emission of isoprene and monoterpenes where measured from the boreal forest floor at the SMEAR II station in Southern Finland (Hari and Kulmala, Boreal Env. Res., 2005) during the snow-free period in 2010-2012. We used a dynamic method with 3 automated chambers analyzed by Proton Transfer Reaction - Mass Spectrometer (Aaltonen et al., Plant Soil, 2013). Using this data, we have developed empirical parameterizations for the emission of isoprene and monoterpenes from the forest floor. These parameterizations depends on abiotic factors, however, since the parameterizations are based on field measurements, biotic features are captured. Further, we have used the 1D chemistry-transport model SOSAA (Boy et al., ACP, 2011) to test the seasonal relative importance of inclusion of these parameterizations of the forest floor compared to the canopy crown emissions, on the atmospheric reactivity throughout the canopy.

Soil microbial communities and metabolic function of a Northern Alabama forest ecosystem

USDA-ARS?s Scientific Manuscript database

Thinning, prescribed burning, and their combinations, are common forest management practices to restore degraded forest communities and to prevent uncontrollable wildfires. However, their impacts on soil microbial communities, which are vital to global element cycling, are traditionally overlooked. ...

Habitat Fragmentation can Modulate Drought Effects on the Plant-soil-microbial System in Mediterranean Holm Oak (Quercus ilex) Forests.

PubMed

Flores-Rentería, Dulce; Curiel Yuste, Jorge; Rincón, Ana; Brearley, Francis Q; García-Gil, Juan Carlos; Valladares, Fernando

2015-05-01

Ecological transformations derived from habitat fragmentation have led to increased threats to above-ground biodiversity. However, the impacts of forest fragmentation on soils and their microbial communities are not well understood. We examined the effects of contrasting fragment sizes on the structure and functioning of soil microbial communities from holm oak forest patches in two bioclimatically different regions of Spain. We used a microcosm approach to simulate the annual summer drought cycle and first autumn rainfall (rewetting), evaluating the functional response of a plant-soil-microbial system. Forest fragment size had a significant effect on physicochemical characteristics and microbial functioning of soils, although the diversity and structure of microbial communities were not affected. The response of our plant-soil-microbial systems to drought was strongly modulated by the bioclimatic conditions and the fragment size from where the soils were obtained. Decreasing fragment size modulated the effects of drought by improving local environmental conditions with higher water and nutrient availability. However, this modulation was stronger for plant-soil-microbial systems built with soils from the northern region (colder and wetter) than for those built with soils from the southern region (warmer and drier) suggesting that the responsiveness of the soil-plant-microbial system to habitat fragmentation was strongly dependent on both the physicochemical characteristics of soils and the historical adaptation of soil microbial communities to specific bioclimatic conditions. This interaction challenges our understanding of future global change scenarios in Mediterranean ecosystems involving drier conditions and increased frequency of forest fragmentation.

Does Long-Term Elevation of CO2 Concentration Increase Photosynthesis in Forest Floor Vegetation? (Indiana Strawberry in a Maryland Forest).

PubMed

Osborne, C. P.; Drake, B. G.; LaRoche, J.; Long, S. P.

1997-05-01

As the partial pressure of CO2 (pCO2) in the atmosphere rises, photorespiratory loss of carbon in C3 photosynthesis will diminish and the net efficiency of light-limited photosynthetic carbon uptake should rise. We tested this expectation for Indiana strawberry (Duchesnea indica) growing on a Maryland forest floor. Open-top chambers were used to elevate the pCO2 of a forest floor habitat to 67 Pa and were paired with control chambers providing an ambient pCO2 of 38 Pa. After 3.5 years, D. indica leaves grown and measured in the elevated pCO2 showed a significantly greater maximum quantum efficiency of net photosynthesis (by 22%) and a lower light compensation point (by 42%) than leaves grown and measured in the control chambers. The quantum efficiency to minimize photorespiration, measured in 1% O2, was the same for controls and plants grown at elevated pCO2. This showed that the maximum efficiency of light-energy transduction into assimilated carbon was not altered by acclimation and that the increase in light-limited photosynthesis at elevated pCO2 was simply a function of the decrease in photorespiration. Acclimation did decrease the ribulose-1,5-bisphosphate carboxylase/oxygenase and light-harvesting chlorophyll protein content of the leaf by more than 30%. These changes were associated with a decreased capacity for light-saturated, but not light-limited, photosynthesis. Even so, leaves of D. indica grown and measured at elevated pCO2 showed greater light-saturated photosynthetic rates than leaves grown and measured at the current atmospheric pCO2. In situ measurements under natural forest floor lighting showed large increases in leaf photosynthesis at elevated pCO2, relative to controls, in both summer and fall. The increase in efficiency of light-limited photosynthesis with elevated pCO2 allowed positive net photosynthetic carbon uptake on days and at locations on the forest floor that light fluxes were insufficient for positive net photosynthesis in the current atmospheric pCO2.

Forest floor and mineral soil respiration rates in a northern Minnesota red pine chronosequence

USGS Publications Warehouse

Powers, Matthew; Kolka, Randall; Bradford, John B.; Palik, Brian J.; Jurgensen, Martin

2018-01-01

We measured total soil CO2 efflux (RS) and efflux from the forest floor layers (RFF) in red pine (Pinus resinosaAit.) stands of different ages to examine relationships between stand age and belowground C cycling. Soil temperature and RS were often lower in a 31-year-old stand (Y31) than in 9-year-old (Y9), 61-year-old (Y61), or 123-year-old (Y123) stands. This pattern was most apparent during warm summer months, but there were no consistent differences in RFF among different-aged stands. RFF represented an average of 4–13% of total soil respiration, and forest floor removal increased moisture content in the mineral soil. We found no evidence of an age effect on the temperature sensitivity of RS, but respiration rates in Y61 and Y123 were less sensitive to low soil moisture than RS in Y9 and Y31. Our results suggest that soil respiration’s sensitivity to soil moisture may change more over the course of stand development than its sensitivity to soil temperature in red pine, and that management activities that alter landscape-scale age distributions in red pine forests could have significant impacts on rates of soil CO2 efflux from this forest type.

Soil microbial communities and enzyme activities in sea-buckthorn (Hippophae rhamnoides) plantation at different ages.

PubMed

Yang, Miao; Yang, Dan; Yu, Xuan

2018-01-01

The aim of this study was to assess the impact of forest age and season on the soil microbial community and enzyme activities in sea-buckthorn plantation system and to determine the relative contributions to soil microbial properties. Soil sampling was carried out in the dry season (April) and wet season (September) in four areas, including: abandoned farmland (NH), an 8-year- old plantation (young plantation, 8Y), a 13-year-old plantation (middle-aged plantation, 13Y), and an 18-year-old plantation (mature plantation, 18Y). The results showed that forest age and season have a significant effect on soil microbial community structure and enzyme activities. The total, bacterial, fungal, Gram-negative (G+), and Gram-positive (G-) PLFAs increased gradually with forest age, with the highest values detected in 18Y. All the detected enzyme activities showed the trend as a consequence of forest age. The microbial PLFAs and soil enzyme activities were higher in the wet season than the dry season. However, there were no significant interactions between forest age and season. A Correlation analysis suggested that soil microbial communities and enzyme activities were significantly and positively correlated with pH, total nitrogen (TN) and available phosphorus (AP). Season had a stronger influence on soil microbial communities than forest age. In general, sea-buckthorn plantations establishment might be a potential tool for maintaining and increasing soil fertility in arid and semi-arid regions.

Soil microbial communities and enzyme activities in sea-buckthorn (Hippophae rhamnoides) plantation at different ages

PubMed Central

Yang, Miao; Yang, Dan

2018-01-01

The aim of this study was to assess the impact of forest age and season on the soil microbial community and enzyme activities in sea-buckthorn plantation system and to determine the relative contributions to soil microbial properties. Soil sampling was carried out in the dry season (April) and wet season (September) in four areas, including: abandoned farmland (NH), an 8-year- old plantation (young plantation, 8Y), a 13-year-old plantation (middle-aged plantation, 13Y), and an 18-year-old plantation (mature plantation, 18Y). The results showed that forest age and season have a significant effect on soil microbial community structure and enzyme activities. The total, bacterial, fungal, Gram-negative (G+), and Gram-positive (G-) PLFAs increased gradually with forest age, with the highest values detected in 18Y. All the detected enzyme activities showed the trend as a consequence of forest age. The microbial PLFAs and soil enzyme activities were higher in the wet season than the dry season. However, there were no significant interactions between forest age and season. A Correlation analysis suggested that soil microbial communities and enzyme activities were significantly and positively correlated with pH, total nitrogen (TN) and available phosphorus (AP). Season had a stronger influence on soil microbial communities than forest age. In general, sea-buckthorn plantations establishment might be a potential tool for maintaining and increasing soil fertility in arid and semi-arid regions. PMID:29324845

Humic fractions of forest, pasture and maize crop soils resulting from microbial activity

PubMed Central

Tavares, Rose Luiza Moraes; Nahas, Ely

2014-01-01

Humic substances result from the degradation of biopolymers of organic residues in the soil due to microbial activity. The objective of this study was to evaluate the influence of three different ecosystems: forest, pasture and maize crop on the formation of soil humic substances relating to their biological and chemical attributes. Microbial biomass carbon (MBC), microbial respiratory activity, nitrification potential, total organic carbon, soluble carbon, humic and fulvic acid fractions and the rate and degree of humification were determined. Organic carbon and soluble carbon contents decreased in the order: forest > pasture > maize; humic and fulvic acids decreased in the order forest > pasture=maize. The MBC and respiratory activity were not influenced by the ecosystems; however, the nitrification potential was higher in the forest than in other soils. The rate and degree of humification were higher in maize soil indicating greater humification of organic matter in this system. All attributes studied decreased significantly with increasing soil depth, with the exception of the rate and degree of humification. Significant and positive correlations were found between humic and fulvic acids contents with MBC, microbial respiration and nitrification potential, suggesting the microbial influence on the differential formation of humic substances of the different ecosystems. PMID:25477932

Use of monitoring and adaptive management to promote regeneration on the Allegheny National Forest

Treesearch

Lois DeMarco; Susan L. Stout

2001-01-01

Forest regeneration in the Allegheny Plateau Region of Pennsylvania is a continual challenge due to an overabundance of white-tailed deer (Odocoileus virginianus Zimmerman) and the resulting density of interfering plants on the forest floor. Guidelines developed to establish regeneration on the Allegheny National Forest rely on the silvical...

Stand and fuel treatments for restoring old-growth ponderosa pine forests in the interior west (Boise Basin Experimental Forest)

Treesearch

Russell T. Graham; Theresa B. Jain

2007-01-01

Fire exclusion, especially in the dry forests (i.e. those dominated or potentially dominated by ponderosa pine) has most often altered tree and shrub composition and structure and, though often overlooked in many locales, the forest floor from conditions that occurred historically (pre-1900).

Variations of soil microbial community structures beneath broadleaved forest trees in temperate and subtropical climate zones

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

Yang, Sihang; Zhang, Yuguang; Cong, Jing

Global warming has shifted climate zones poleward or upward. Furthermore, understanding the responses and mechanism of microbial community structure and functions relevant to natural climate zone succession is challenged by the high complexity of microbial communities. Here, we examined soil microbial community in three broadleaved forests located in the Wulu Mountain (WLM, temperate climate), Funiu Mountain (FNM, at the border of temperate and subtropical climate zones), or Shennongjia Mountain (SNJ, subtropical climate). Although plant species richness decreased with latitudes, the microbial taxonomic α-diversity increased with latitudes, concomitant with increases in soil total and available nitrogen and phosphorus contents. Phylogenetic NRImore » (Net Relatedness Index) values increased from 0.718 in temperate zone (WLM) to 1.042 in subtropical zone (SNJ), showing a shift from over dispersion to clustering likely caused by environmental filtering such as low pH and nutrients. Similarly, taxonomybased association networks of subtropical forest samples were larger and tighter, suggesting clustering. In contrast, functional α-diversity was similar among three forests, but functional gene networks of the FNM forest significantly (P < 0.050) differed from the others. A significant correlation (R = 0.616, P < 0.001) between taxonomic and functional β-diversity was observed only in the FNM forest, suggesting low functional redundancy at the border of climate zones. Using a strategy of space-fortime substitution, we predict that poleward climate range shift will lead to decreased microbial taxonomic α-diversities in broadleaved forest.« less

Variations of soil microbial community structures beneath broadleaved forest trees in temperate and subtropical climate zones

DOE PAGES

Yang, Sihang; Zhang, Yuguang; Cong, Jing; ...

2017-02-10

Global warming has shifted climate zones poleward or upward. Furthermore, understanding the responses and mechanism of microbial community structure and functions relevant to natural climate zone succession is challenged by the high complexity of microbial communities. Here, we examined soil microbial community in three broadleaved forests located in the Wulu Mountain (WLM, temperate climate), Funiu Mountain (FNM, at the border of temperate and subtropical climate zones), or Shennongjia Mountain (SNJ, subtropical climate). Although plant species richness decreased with latitudes, the microbial taxonomic α-diversity increased with latitudes, concomitant with increases in soil total and available nitrogen and phosphorus contents. Phylogenetic NRImore » (Net Relatedness Index) values increased from 0.718 in temperate zone (WLM) to 1.042 in subtropical zone (SNJ), showing a shift from over dispersion to clustering likely caused by environmental filtering such as low pH and nutrients. Similarly, taxonomybased association networks of subtropical forest samples were larger and tighter, suggesting clustering. In contrast, functional α-diversity was similar among three forests, but functional gene networks of the FNM forest significantly (P < 0.050) differed from the others. A significant correlation (R = 0.616, P < 0.001) between taxonomic and functional β-diversity was observed only in the FNM forest, suggesting low functional redundancy at the border of climate zones. Using a strategy of space-fortime substitution, we predict that poleward climate range shift will lead to decreased microbial taxonomic α-diversities in broadleaved forest.« less

How much will afforestation of former cropland influence soil C stocks? A synthesis of paired sampling, chronosequence sampling and repeated sampling studies

NASA Astrophysics Data System (ADS)

Vesterdal, Lars; Hansen, K.; Stupak, I.; Don, Axel; Poeplau, C.; Leifeld, Jens; van Wesemael, Bas

2010-05-01

The need for documentation of land-use change effects on soil C is high on the agenda in most signatory countries to the Kyoto Protocol. Large land areas in Europe have experienced land-use change from cropland to forest since 1990 by direct afforestation as well as abandonment and regrowth of marginally productive cropland. Soil C dynamics following land-use change remain highly uncertain due to a limited number of available studies and due to influence of interacting factors such as land use history, soil type, and climate. Common approaches for estimation of potential soil C changes following land-use change are i) paired sampling of plots with a long legacy of different land uses, ii) chronosequence studies of land-use change, and lastly iii) repeated sampling of plots subject to changed land use. This paper will synthesize the quantitative effects of cropland afforestation on soil C sequestration based on all three approaches and will report on related work within Cost 639. Paired plots of forest and cropland were used to study the general differences between soil C stocks in the two land uses. At 27 sites in Denmark distributed among different regions and soil types forest floor and mineral soil were sampled in and around soil pits. Soil C stocks were higher in forest than cropland (mean difference 22 Mg C ha-1 to 1 m depth). This difference was caused solely by the presence of a forest floor in forests; mineral soil C stocks were similar (108 vs. 109 Mg C ha-1) in the two land uses regardless of soil type and the soil layers considered. The chronosequence approach was employed in the AFFOREST project for evaluation of C sequestration in biomass and soils following afforestation of cropland. Two oak (Quercus robur) and four Norway spruce (Picea abies) afforestation chronosequences (age range 1 to 90 years) were studied in Denmark, Sweden and the Netherlands. Forest floor and mineral soil (0-25 cm) C contents were as a minimum unchanged and in most cases there was net C sequestration (range 0-1.3 Mg C ha-1 yr-1). The allocation of sequestered soil C was quite different among chronosequences; forest floors consistently sequestered C (0.1-0.7 Mg C ha-1 yr-1) but there was no general pattern in mineral soil C sequestration. While the paired sampling and the chronosequence approaches both may be confounded by site factors other than the land use, repeated sampling of plots best addresses the pure land-use change effect. Repeated sampling after 18 years was done in a systematic 7x7 km grid to address soil C changes in 15 cropland plots that were converted to forest (7-22 years since afforestation). Consistent with the other two approaches, detectable soil C changes were confined to the forest floor component; forest floor C sequestration rates were 0.24 Mg C ha-1 yr-1 while no changes were detected for mineral soils. The three approaches to estimation of soil C sequestration indeed point to a common conclusion: The potential for soil C sequestration is mainly confined to the forest floor whereas notable C sequestration is less likely to occur in the mineral soil. However, more generalizable knowledge is badly needed for reporting of land-use change effects on mineral soil C pools. WG II of Cost 639 and the FP7 project GHG Europe is currently establishing a database of LUC studies. This database will be used to establish so-called Carbon Response Functions (CRF), i.e. simple models predicting the annual rate of change in soil C pools. These CRFs may serve as tools for syntheses of land-use change effects for Europe as well as for improved reporting of soil C dynamics following land-use change.

A metagenomic survey of forest soil microbial communities more than a decade after timber harvesting.

PubMed

Wilhelm, Roland C; Cardenas, Erick; Leung, Hilary; Maas, Kendra; Hartmann, Martin; Hahn, Aria; Hallam, Steven; Mohn, William W

2017-01-01

The scarcity of long-term data on soil microbial communities in the decades following timber harvesting limits current understanding of the ecological problems associated with maintaining the productivity of managed forests. The high complexity of soil communities and the heterogeneity of forest and soil necessitates a comprehensive approach to understand the role of microbial processes in managed forest ecosystems. Here, we describe a curated collection of well replicated, multi-faceted data from eighteen reforested sites in six different North American ecozones within the Long-term Soil Productivity (LTSP) Study, without detailed analysis of results or discussion. The experiments were designed to contrast microbial community composition and function among forest soils from harvested treatment plots with varying intensities of organic matter removal. The collection includes 724 bacterial (16S) and 658 fungal (ITS2) amplicon libraries, 133 shotgun metagenomic libraries as well as stable isotope probing amplicon libraries capturing the effects of harvesting on hemicellulolytic and cellulolytic populations. This collection serves as a foundation for the LTSP Study and other studies of the ecology of forest soil and forest disturbance.

A metagenomic survey of forest soil microbial communities more than a decade after timber harvesting

PubMed Central

Wilhelm, Roland C.; Cardenas, Erick; Leung, Hilary; Maas, Kendra; Hartmann, Martin; Hahn, Aria; Hallam, Steven; Mohn, William W.

2017-01-01

The scarcity of long-term data on soil microbial communities in the decades following timber harvesting limits current understanding of the ecological problems associated with maintaining the productivity of managed forests. The high complexity of soil communities and the heterogeneity of forest and soil necessitates a comprehensive approach to understand the role of microbial processes in managed forest ecosystems. Here, we describe a curated collection of well replicated, multi-faceted data from eighteen reforested sites in six different North American ecozones within the Long-term Soil Productivity (LTSP) Study, without detailed analysis of results or discussion. The experiments were designed to contrast microbial community composition and function among forest soils from harvested treatment plots with varying intensities of organic matter removal. The collection includes 724 bacterial (16S) and 658 fungal (ITS2) amplicon libraries, 133 shotgun metagenomic libraries as well as stable isotope probing amplicon libraries capturing the effects of harvesting on hemicellulolytic and cellulolytic populations. This collection serves as a foundation for the LTSP Study and other studies of the ecology of forest soil and forest disturbance. PMID:28765786

The contributions of forest structure and substrate to bryophyte diversity and abundance in mature coniferous forests of the Pacific Northwest

Treesearch

Shelley A. Evans; Charles B. Halpern; Donald McKenzie

2012-01-01

Many aspects of forest structure are thought to contribute to the presence, abundance, and diversity of forest-floor bryophytes. To what extent easily measured characteristics of local environment (overstory structure or substrate availability) explain patterns of abundance and diversity remains unclear in most forest ecosystems. We explore these relationships in four...

Changes in Microbial Nitrogen Across a 100-Year Chronosequence of Upland Hardwood Forests

Treesearch

Travis W. Idol; Phillip E. Pope; Felix, Jr. Ponder

2002-01-01

Soil microorganisms mediate many of the major processes involved in soil N cycling. Also, they are strong competitors with plants for available soil N. Thus, changes in microbial N because of forest harvesting may have significant impacts on N availability and overall forest N cycling. A chronosequence of upland hardwood forest stands in southern Indiana, USA, ranging...

Species-specific effects of Asian and European earthworms on microbial communities in Mid-Atlantic deciduous forests

USDA-ARS?s Scientific Manuscript database

Earthworm species with different feeding, burrowing, and/or casting behaviors can lead to distinct microbial communities through complex direct and indirect processes. European earthworm invasion into temperate deciduous forests in North America has been shown to alter microbial biomass in the soil ...

Effects of nitrogen and phosphorus additions on soil microbial biomass and community structure in two reforested tropical forests

PubMed Central

Liu, Lei; Gundersen, Per; Zhang, Wei; Zhang, Tao; Chen, Hao; Mo, Jiangming

2015-01-01

Elevated nitrogen (N) deposition may aggravate phosphorus (P) deficiency in forests in the warm humid regions of China. To our knowledge, the interactive effects of long-term N deposition and P availability on soil microorganisms in tropical replanted forests remain unclear. We conducted an N and P manipulation experiment with four treatments: control, N addition (15 g N m−2·yr−1), P addition (15 g P m−2·yr−1), and N and P addition (15 + 15 g N and P m−2·yr−1, respectively) in disturbed (planted pine forest with recent harvests of understory vegetation and litter) and rehabilitated (planted with pine, but mixed with broadleaf returning by natural succession) forests in southern China. Nitrogen addition did not significantly affect soil microbial biomass, but significantly decreased the abundance of gram-negative bacteria PLFAs in both forest types. Microbial biomass increased significantly after P addition in the disturbed forest but not in the rehabilitated forest. No interactions between N and P additions on soil microorganisms were observed in either forest type. Our results suggest that microbial growth in replanted forests of southern China may be limited by P rather than by N, and this P limitation may be greater in disturbed forests. PMID:26395406

“Edifice Rex” Sulfide Recovery Project: Analysis of submarine hydrothermal, microbial habitat

NASA Astrophysics Data System (ADS)

Delaney, John R.; Kelley, Deborah S.; Mathez, Edmond A.; Yoerger, Dana R.; Baross, John; Schrenk, Matt O.; Tivey, Margaret K.; Kaye, Jonathan; Robigou, Veronique

Recent scientific developments place inquiries about submarine volcanic systems in a broad planetary context. Among these is the discovery that submarine eruptions are intimately linked with massive effusions of microbes and their products from below the sea floor [Holden et al., 1998]. This material includes microbes that only grow at temperatures tens of degrees higher than the temperatures of the vent fluids from which they were sampled. Such results lend support for the existence of a potentially extensive, but currently unexplored sub-sea floor microbial biosphere associated with active submarine volcanoes [Deming and Baross, 1993; Delaney et al., 1998; Summit and Baross, 1998].

[Effects of altitudes on soil microbial biomass and enzyme activity in alpine-gorge regions.

PubMed

Cao, Rui; Wu, Fu Zhong; Yang, Wan Qin; Xu, Zhen Feng; Tani, Bo; Wang, Bin; Li, Jun; Chang, Chen Hui

2016-04-22

In order to understand the variations of soil microbial biomass and soil enzyme activities with the change of altitude, a field incubation was conducted in dry valley, ecotone between dry valley and mountain forest, subalpine coniferous forest, alpine forest and alpine meadow from 1563 m to 3994 m of altitude in the alpine-gorge region of western Sichuan. The microbial biomass carbon and nitrogen, and the activities of invertase, urease and acid phosphorus were measured in both soil organic layer and mineral soil layer. Both the soil microbial biomass and soil enzyme activities showed the similar tendency in soil organic layer. They increased from 2158 m to 3028 m, then decreased to the lowest value at 3593 m, and thereafter increased until 3994 m in the alpine-gorge region. In contrast, the soil microbial biomass and soil enzyme activities in mineral soil layer showed the trends as, the subalpine forest at 3028 m > alpine meadow at 3994 m > montane forest ecotone at 2158 m > alpine forest at 3593 m > dry valley at 1563 m. Regardless of altitudes, soil microbial biomass and soil enzyme activities were significantly higher in soil organic layer than in mineral soil layer. The soil microbial biomass was significantly positively correlated with the activities of the measured soil enzymes. Moreover, both the soil microbial biomass and soil enzyme activities were significantly positively correlated with soil water content, organic carbon, and total nitrogen. The activity of soil invertase was significantly positively correlated with soil phosphorus content, and the soil acid phosphatase was so with soil phosphorus content and soil temperature. In brief, changes in vegetation and other environmental factors resulting from altitude change might have strong effects on soil biochemical properties in the alpine-gorge region.

Contrasting the microbiomes from forest rhizosphere and deeper bulk soil from an Amazon rainforest reserve.

PubMed

Fonseca, Jose Pedro; Hoffmann, Luisa; Cabral, Bianca Catarina Azeredo; Dias, Victor Hugo Giordano; Miranda, Marcio Rodrigues; de Azevedo Martins, Allan Cezar; Boschiero, Clarissa; Bastos, Wanderley Rodrigues; Silva, Rosane

2018-02-05

Pristine forest ecosystems provide a unique perspective for the study of plant-associated microbiota since they host a great microbial diversity. Although the Amazon forest is one of the hotspots of biodiversity around the world, few metagenomic studies described its microbial community diversity thus far. Understanding the environmental factors that can cause shifts in microbial profiles is key to improving soil health and biogeochemical cycles. Here we report a taxonomic and functional characterization of the microbiome from the rhizosphere of Brosimum guianense (Snakewood), a native tree, and bulk soil samples from a pristine Brazilian Amazon forest reserve (Cuniã), for the first time by the shotgun approach. We identified several fungi and bacteria taxon significantly enriched in forest rhizosphere compared to bulk soil samples. For archaea, the trend was the opposite, with many archaeal phylum and families being considerably more enriched in bulk soil compared to forest rhizosphere. Several fungal and bacterial decomposers like Postia placenta and Catenulispora acidiphila which help maintain healthy forest ecosystems were found enriched in our samples. Other bacterial species involved in nitrogen (Nitrobacter hamburgensis and Rhodopseudomonas palustris) and carbon cycling (Oligotropha carboxidovorans) were overrepresented in our samples indicating the importance of these metabolic pathways for the Amazon rainforest reserve soil health. Hierarchical clustering based on taxonomic similar microbial profiles grouped the forest rhizosphere samples in a distinct clade separated from bulk soil samples. Principal coordinate analysis of our samples with publicly available metagenomes from the Amazon region showed grouping into specific rhizosphere and bulk soil clusters, further indicating distinct microbial community profiles. In this work, we reported significant shifts in microbial community structure between forest rhizosphere and bulk soil samples from an Amazon forest reserve that are probably caused by more than one environmental factors such as rhizosphere and soil depth. Copyright © 2017 Elsevier B.V. All rights reserved.

Canopy soil bacterial communities altered by severing host tree limbs

PubMed Central

Dangerfield, Cody R.; Nadkarni, Nalini M.

2017-01-01

Trees of temperate rainforests host a large biomass of epiphytic plants, which are associated with soils formed in the forest canopy. Falling of epiphytic material results in the transfer of carbon and nutrients from the canopy to the forest floor. This study provides the first characterization of bacterial communities in canopy soils enabled by high-depth environmental sequencing of 16S rRNA genes. Canopy soil included many of the same major taxonomic groups of Bacteria that are also found in ground soil, but canopy bacterial communities were lower in diversity and contained different operational taxonomic units. A field experiment was conducted with epiphytic material from six Acer macrophyllum trees in Olympic National Park, Washington, USA to document changes in the bacterial communities of soils associated with epiphytic material that falls to the forest floor. Bacterial diversity and composition of canopy soil was highly similar, but not identical, to adjacent ground soil two years after transfer to the forest floor, indicating that canopy bacteria are almost, but not completely, replaced by ground soil bacteria. Furthermore, soil associated with epiphytic material on branches that were severed from the host tree and suspended in the canopy contained altered bacterial communities that were distinct from those in canopy material moved to the forest floor. Therefore, the unique nature of canopy soil bacteria is determined in part by the host tree and not only by the physical environmental conditions associated with the canopy. Connection to the living tree appears to be a key feature of the canopy habitat. These results represent an initial survey of bacterial diversity of the canopy and provide a foundation upon which future studies can more fully investigate the ecological and evolutionary dynamics of these communities. PMID:28894646

Canopy soil bacterial communities altered by severing host tree limbs.

PubMed

Dangerfield, Cody R; Nadkarni, Nalini M; Brazelton, William J

2017-01-01

Trees of temperate rainforests host a large biomass of epiphytic plants, which are associated with soils formed in the forest canopy. Falling of epiphytic material results in the transfer of carbon and nutrients from the canopy to the forest floor. This study provides the first characterization of bacterial communities in canopy soils enabled by high-depth environmental sequencing of 16S rRNA genes. Canopy soil included many of the same major taxonomic groups of Bacteria that are also found in ground soil, but canopy bacterial communities were lower in diversity and contained different operational taxonomic units. A field experiment was conducted with epiphytic material from six Acer macrophyllum trees in Olympic National Park, Washington, USA to document changes in the bacterial communities of soils associated with epiphytic material that falls to the forest floor. Bacterial diversity and composition of canopy soil was highly similar, but not identical, to adjacent ground soil two years after transfer to the forest floor, indicating that canopy bacteria are almost, but not completely, replaced by ground soil bacteria. Furthermore, soil associated with epiphytic material on branches that were severed from the host tree and suspended in the canopy contained altered bacterial communities that were distinct from those in canopy material moved to the forest floor. Therefore, the unique nature of canopy soil bacteria is determined in part by the host tree and not only by the physical environmental conditions associated with the canopy. Connection to the living tree appears to be a key feature of the canopy habitat. These results represent an initial survey of bacterial diversity of the canopy and provide a foundation upon which future studies can more fully investigate the ecological and evolutionary dynamics of these communities.

Measuring moisture dynamics to predict fire severity in longleaf pine forests.

Treesearch

Sue A. Ferguson; Julia E. Ruthford; Steven J. McKay; David Wright; Clint Wright; Roger Ottmar

2002-01-01

To understand the combustion limit of biomass fuels in a longleaf pine (Pinus palustris) forest, an experiment was conducted to monitor the moisture content of potentially flammable forest floor materials (litter and duff) at Eglin Air Force Base in the Florida Panhandle. While longleaf pine forests are fire dependent ecosystems, a long history of...

Interactions between white-tailed deer density and the composition of forest understories in the northern United States

Treesearch

Matthew B. Russell; Christopher W. Woodall; Kevin M. Potter; Brian F. Walters; Grant M. Domke; Christopher M. Oswalt

2017-01-01

Forest understories across the northern United States (US) are a complex of tree seedlings, endemic forbs, herbs, shrubs, and introduced plant species within a forest structure defined by tree and forest floor attributes. The substantial increase in white-tailed deer (Odocoileus virginianus Zimmerman) populations over the past decades has resulted...

How to estimate forest carbon for large areas from inventory data

Treesearch

James E. Smith; Linda S. Heath; Peter B. Woodbury

2004-01-01

Carbon sequestration through forest growth provides a low-cost approach for meeting state and national goals to reduce net accumulations of atmospheric carbon dioxide. Total forest ecosystem carbon stocks include "pools" in live trees, standing dead trees, understory vegetation, down dead wood, forest floor, and soil. Determining the level of carbon stocks in...

Hypholoma lateritium isolated from coarse woody debris, the forest floor, and mineral soil in a deciduous forest in New Hampshire

Treesearch

Therese A. Thompson; R. Greg Thorn; Kevin T. Smith

2012-01-01

Fungi in the Agaricomycetes (Basidiomycota) are the primary decomposers in temperate forests of dead wood on and in the forest soil. Through the use of isolation techniques selective for saprotrophic Agaricomycetes, a variety of wood decay fungi were isolated from a northern hardwood stand in the Bartlett Experimental Forest, New Hampshire, USA. In particular,

Biogeography and organic matter removal shape long-term effects of timber harvesting on forest soil microbial communities

Treesearch

Roland C Wilhelm; Erick Cardenas; Kendra R Maas; Hilary Leung; Larisa McNeil; Shannon Berch; William Chapman; Graeme Hope; J M Kranabetter; Stephane Dubé; Matt Busse; Robert Fleming; Paul Hazlett; Kara L Webster; David Morris; D Andrew Scott; William W Mohn

2017-01-01

The growing demand for renewable, carbon-neutral materials and energy is leading to intensified forest land-use. The long-term ecological challenges associated with maintaining soil fertility in managed forests are not yet known, in part due to the complexity of soil microbial communities and the heterogeneity of forest soils. This study determined the long-term...

Fog and Phosphorous:Mist Connections?

NASA Astrophysics Data System (ADS)

Weathers, K. C.; Caraco, N. F.; Ewing, H. A.

2005-12-01

Fog (or cloud) is an important vector for delivering water, nutrients and pollutants to many coastal and montane ecosystems worldwide. Previous research has demonstrated that elements and ions whose sources are thought to be atmospheric, such as nitrogen and sulfur, can be deposited in substantial quantities via fog water deposition. However, the ecologically-important nutrient, phosphorous (P), is thought to derive primarily from guano or terrestrial sources; it has not been demonstrated to be deposited in significant quantities via rain water, for example. Here we suggest that phosphorous may be quite prevalent in fog water and that the atmospheric deposition of phosphorous to the forest floor is significant. Phosphate appears to be either immobilized or utilized in the forest floor. We examine the concentrations of phosphorous in fog water from several ecosystems in the Americas and the spatial patterns of P movement in a fog-dominated, redwood forest in Sonoma County, CA. Phosphate concentrations were surprisingly high, ranging from 0.002 to 2.9 mg/L, in fog samples from near-coast and montane ecosystems. Phosphate in fog water appears to be derived from a crustal source as demonstrated by the strong relationship between phosphorous concentrations in fog and K:Na ratios. Fog water phosphorous inputs to the forest floor were observed to decline exponentially and vary significantly from edge to interior in a redwood forest. Phosphate via fog deposition can be detected in shallow soil zones but not at greater depths, and only at the forest edge, during the summer fog season.

Increased Calcium Availability Leads to Greater Forest Floor Accumulation in an Adirondack Forest

NASA Astrophysics Data System (ADS)

Melvin, A.; Goodale, C. L.

2010-12-01

Nutrient availability in Northeastern US forests has been dramatically altered by anthropogenic activities. Acid deposition has not only increased nitrogen (N) availability, but has also been linked to soil acidification and a loss of base cations, largely calcium (Ca). We are studying the long-term effects of a Ca addition on carbon (C) and N cycling in a forested catchment in the Adirondack Park, New York. In 1989, calcium carbonate (lime) was added to two subcatchments within the Woods Lake Watershed to ameliorate the effects of soil Ca depletion. Two additional subcatchments were left as controls. Eighteen years after the Ca application, both soil pH and exchangeable Ca concentrations remain elevated in the organic horizons and upper mineral soils of the treated subcatchments. The forest floor mass in this watershed is very large and measurements show that the organic layer in the limed subcatchments is significantly larger than in the controls (212 t/ha vs. 116 t/ha), resulting in greater C and N stocks in the Ca-amended soils. This finding suggests that Ca may stabilize soil organic matter (SOM), resulting in greater C storage under high soil Ca conditions. We are investigating potential drivers of this SOM accumulation in the limed subcatchments, including rates of leaf litter production and the decomposition rate of forest floor material. This work will provide important insights into how long-term changes in soil Ca availability influence SOM stabilization, retention and nutrient cycling.

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

Hesse, Cedar N.; Mueller, Rebecca C.; Vuyisich, Momchilo

Anthropogenic N deposition alters patterns of C and N cycling in temperate forests, where forest floor litter decomposition is a key process mediated by a diverse community of bacteria and fungi. To track forest floor decomposer activity we generated metatranscriptomes that simultaneously surveyed the actively expressed bacterial and eukaryote genes in the forest floor, to compare the impact of N deposition on the decomposers in two natural maple forests in Michigan, USA, where replicate field plots had been amended with N for 16 years. Site and N amendment responses were compared using about 74,000 carbohydrate active enzyme transcript sequences (CAZymes)more » in each metatranscriptome. Parallel ribosomal RNA (rRNA) surveys of bacterial and fungal biomass and taxonomic composition showed no significant differences in either biomass or OTU richness between the two sites or in response to N. Site and N amendment were not significant variables defining bacterial taxonomic composition, but they were significant for fungal community composition, explaining 17 and 14% of the variability, respectively. The relative abundance of expressed bacterial and fungal CAZymes changed significantly with N amendment in one of the forests, and N-response trends were also identified in the second forest. Although the two ambient forests were similar in community biomass, taxonomic structure and active CAZyme profile, the shifts in active CAZyme profiles in response to N-amendment differed between the sites. One site responded with an over-expression of bacterial CAZymes, and the other site responded with an over-expression of both fungal and different bacterial CAZymes. Both sites showed reduced representation of fungal lignocellulose degrading enzymes in N-amendment plots. The metatranscriptome approach provided a holistic assessment of eukaryote and bacterial gene expression and is applicable to other systems where eukaryotes and bacteria interact.« less

Fire severity alters the distribution of pyrogenic carbon stocks across ecosystem pools in a Californian mixed-conifer forest

NASA Astrophysics Data System (ADS)

Maestrini, Bernardo; Alvey, Erin C.; Hurteau, Matthew D.; Safford, Hugh; Miesel, Jessica R.

2017-09-01

Pyrogenic carbon (PyC) is hypothesized to play an important role in the carbon (C) cycle due to its resistance to decomposition; however, much uncertainty still exists regarding the stocks of PyC that persist on-site after the initial erosion in postfire forests. Therefore, understanding how fire characteristics influence PyC stocks is vital, particularly in the context of California forests for which an increase of high-severity fires is predicted over the next decades. We measured forest C and persistent PyC stocks in areas burned by low-to-moderate and high-severity fire, as well as in adjacent unburned areas in a California mixed-conifer forest, 2 to 3 years after wildfire. We measured C and PyC stocks in the following compartments: standing trees, downed wood, forest floor, and mineral soil (0-5 cm), and we identified PyC using the weak nitric acid digestion method. We found that the total stock of PyC did not differ among fire severity classes (overall mean 248 ± 30 g C m-2); however, fire severity influenced the distribution of PyC in the individual compartments. Areas burned by high-severity fire had 2.5 times more PyC stocked in the coarse woody debris (p < 0.05), 3.3 times more PyC stocked in standing trees (p < 0.05), and a lower PyC stock in the forest floor (-22%, p < 0.05) compared to low-to-moderate fire severity areas. These results have important implications for the permanence time of PyC, which is putatively higher in standing trees and coarse woody debris compared to the forest floor, where it is susceptible to rapid losses through erosion.

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.

Root and Rhizosphere Bacterial Phosphatase Activity Varies with Tree Species and Soil Phosphorus Availability in Puerto Rico Tropical Forest

DOE PAGES

Cabugao, Kristine Grace M.; Timm, Collin M.; Carrell, Alyssa A.; ...

2017-10-30

Climatic conditions in tropical forests combined with the immobility of phosphorus due to sorption on mineral surfaces or result in soils typically lacking in the form of phosphorus (orthophosphate) most easily metabolized by plants and microbes. In these soils, mineralization of organic phosphorus can be the major source for labile inorganic P available for uptake. Both plants and microbes encode for phosphatase enzymes capable of mineralizing a range of organic phosphorus compounds. However, the activity of these enzymes depends on several edaphic factors including P availability and tree or microbial species. Thus, phosphatase activity in both roots and the rootmore » microbial community constitute an important role in P mineralization and P nutrient dynamics that are not well studied in tropical forests. We measured phosphatase activity in roots and bacterial isolates from the microbial community of six tree species from three forest sites differing in phosphorus availability in the Luquillo Mountains of Puerto Rico. Root and microbial phosphatase activity were both influenced by tree identity and soil phosphorus availability. However, tree identity had a larger effect on phosphatase activity (effect size = 0.12) than soil phosphorus availability (effect size = 0.07). In addition, lower amounts of P availability corresponded with higher levels of enzyme activity. In contrast, ANOSIM analysis of the weighted UniFrac distance matrix indicates that microbial community composition was more strongly controlled by soil P availability (P value < 0.05). These results indicate that root and rhizosphere microbial phosphatase activity are similarly expressed despite the slightly stronger influence of tree identity on root function and the stronger influence of P availability on microbial community composition. The low levels of orthophosphate in tropical forests, rather than prohibiting growth, have encouraged a variety of functions to adapt to minimal levels of an essential nutrient. Phosphatase activity is one such mechanism that varies in both roots and microbial community members. A thorough understanding of phosphatase activity provides insight into P mineralization in tropical forests, providing not only perspective on ecosystem function of tropical trees and microbial communities, but also in advancing efforts to improve representations of tropical forests in future climates.« less

Root and Rhizosphere Bacterial Phosphatase Activity Varies with Tree Species and Soil Phosphorus Availability in Puerto Rico Tropical Forest

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

Cabugao, Kristine Grace M.; Timm, Collin M.; Carrell, Alyssa A.

Climatic conditions in tropical forests combined with the immobility of phosphorus due to sorption on mineral surfaces or result in soils typically lacking in the form of phosphorus (orthophosphate) most easily metabolized by plants and microbes. In these soils, mineralization of organic phosphorus can be the major source for labile inorganic P available for uptake. Both plants and microbes encode for phosphatase enzymes capable of mineralizing a range of organic phosphorus compounds. However, the activity of these enzymes depends on several edaphic factors including P availability and tree or microbial species. Thus, phosphatase activity in both roots and the rootmore » microbial community constitute an important role in P mineralization and P nutrient dynamics that are not well studied in tropical forests. We measured phosphatase activity in roots and bacterial isolates from the microbial community of six tree species from three forest sites differing in phosphorus availability in the Luquillo Mountains of Puerto Rico. Root and microbial phosphatase activity were both influenced by tree identity and soil phosphorus availability. However, tree identity had a larger effect on phosphatase activity (effect size = 0.12) than soil phosphorus availability (effect size = 0.07). In addition, lower amounts of P availability corresponded with higher levels of enzyme activity. In contrast, ANOSIM analysis of the weighted UniFrac distance matrix indicates that microbial community composition was more strongly controlled by soil P availability (P value < 0.05). These results indicate that root and rhizosphere microbial phosphatase activity are similarly expressed despite the slightly stronger influence of tree identity on root function and the stronger influence of P availability on microbial community composition. The low levels of orthophosphate in tropical forests, rather than prohibiting growth, have encouraged a variety of functions to adapt to minimal levels of an essential nutrient. Phosphatase activity is one such mechanism that varies in both roots and microbial community members. A thorough understanding of phosphatase activity provides insight into P mineralization in tropical forests, providing not only perspective on ecosystem function of tropical trees and microbial communities, but also in advancing efforts to improve representations of tropical forests in future climates.« less

Small mammals in young forests: implications for management for sustainability.

Treesearch

A.B. Carey; C.A. Harrington

2001-01-01

Small mammals have been proposed as indicators of sustainability in forests in the Pacific Northwest and elsewhere. Mammal community composition and species abundances purportedly result from interactions among species, forest-floor characteristics, large coarse woody debris, understory vegetation, and overstory composition. Coarse woody debris is thought to be...

Preliminary guidelines for prescribed burning under standing timber in western larch/douglas-fir forests

Treesearch

Rodney A. Norum

1977-01-01

Guidelines are offered for safe, effective fire treatments in western larch/Douglas-fir forests. Describes procedures for estimating and limiting the scorching of tree crows. Provides a method for predicting percentage of the forest floor that will be burned down to mineral soil.

Transformations of DOM in forested catchments: the pathways of DOM from litter and soil to river export

NASA Astrophysics Data System (ADS)

Lajtha, K.; Yano, Y.; Crow, S.; Kaushal, S.

2006-12-01

Although the quality and quantity of DOM ultimately derives from plant detritus and soils in watersheds, three is substantial alteration of DOM as it passes from litter through the terrestrial landscape. As DOM is generated from plant and microbial detritus and processing, different fractions may be lost via respiration, form quasi-stable soil organic matter, or be temporarily sorbed to soil minerals. We followed the fate of DOC and DON from forested plots with experimentally altered detritus loads to determine the relative roles of original plant litter chemistry and soil transformations. Our study site was the DIRT (Detrital Input and Removal Treatment) plots at the H.J. Andrews Experimental Forest in Oregon, where treatments include detrital additions (wood vs. needle litter), litter exclusion, and root exclusions. Fractionation of detritus leachate solutions demonstrated significant differences in DOC chemistry from different detrital sources. Root leachates produced high quantities of hydrophilic neutral DOC, a fraction rich in labile sugars and polysaccharides; young wood extracts produced higher quantities of weak hydrophobic acids and hydrophobic neutrals (longer chain hydrocarbons); older wood had lower quantities of most labile constituents but was rich in strong hydrophobic acids. Although laboratory extracts of different litter types showed differences in DOM chemistry, soil solutions collected just below the forest floor from the differing detrital treatments were remarkably uniform and poor in labile constituents, suggesting microbial equalization of DOM leachate in the field. DOM quality and concentrations changed significantly with passage through soil profiles. DOC concentrations decreased through the soil profile in all plots to a greater degree than did dissolved organic nitrogen (DON), most likely due to preferential sorption of high C:N hydrophobic dissolved organic matter (DOM) in upper horizons. Percent hydrophobic DOM decreased significantly with depth, and the remaining hydrophilic DOM had a much lower and narrower C:N ratio than hydrophobic DOM. We also hypothesize that protein-reactive polyphenols, or tannins, may contribute to the decreased lability of N-rich DOM in soil solutions and thus significantly influence the quality of DOM delivered to streams.

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.

Searching for signatures across microbial communities: Metagenomic analysis of soil samples from mangrove and other ecosystems.

PubMed

Imchen, Madangchanok; Kumavath, Ranjith; Barh, Debmalya; Azevedo, Vasco; Ghosh, Preetam; Viana, Marcus; Wattam, Alice R

2017-08-18

In this study, we categorize the microbial community in mangrove sediment samples from four different locations within a vast mangrove system in Kerala, India. We compared this data to other samples taken from the other known mangrove data, a tropical rainforest, and ocean sediment. An examination of the microbial communities from a large mangrove forest that stretches across southwestern India showed strong similarities across the higher taxonomic levels. When ocean sediment and a single isolate from a tropical rain forest were included in the analysis, a strong pattern emerged with Bacteria from the phylum Proteobacteria being the prominent taxon among the forest samples. The ocean samples were predominantly Archaea, with Euryarchaeota as the dominant phylum. Principal component and functional analyses grouped the samples isolated from forests, including those from disparate mangrove forests and the tropical rain forest, from the ocean. Our findings show similar patterns in samples were isolated from forests, and these were distinct from the ocean sediment isolates. The taxonomic structure was maintained to the level of class, and functional analysis of the genes present also displayed these similarities. Our report for the first time shows the richness of microbial diversity in the Kerala coast and its differences with tropical rain forest and ocean microbiome.

Using FIA data to inform United States forest carbon national-level accounting needs: 1990-2010

Treesearch

Linda S. Heath

2013-01-01

Forests are partially made up of carbon. Live vegetation, dead wood, forest floor, and soil all contain carbon. Through the process of photosynthesis, trees reduce carbon dioxide to carbohydrates and store the carbon in wood. By removing carbon dioxide from the atmosphere, forests mitigate climate change that may be brought on by increased atmospheric CO2...

Forest water contamination

Treesearch

Roger M. Rowell

2006-01-01

Forests play a key role in cleaning water. Precipitation is “'filtered” through the tree canopy and filtered again throuph the organic matter on the forest floor. The water then seeps into the subsurface to replenish the ground water. Approximately 80% of the freshwater in the United States originates in the 650 million acres (265 million hectares) of forest that...

Beyond CO2 - Tackling the full greenhouse gas budget of a sub-alpine forest ecosystem

NASA Astrophysics Data System (ADS)

Burri, Susanne; Merbold, Lutz; Meier, Philip; Eugster, Werner; Hörtnagl, Lukas; Buchmann, Nina

2017-04-01

In order to tackle the full greenhouse gas (GHG) budgets of forest ecosystems, it is desirable but challenging to quantify the three major GHGs, i.e. CO2, CH4 and N2O simultaneously in-situ. At the long-term forest research site Davos (Candidate Class I Ecosystem Station within the Integrated Carbon Observation System - ICOS), we have recently installed a state-of-the-art measuring system simultaneously to observe the three GHGs on a high temporal resolution and both within and above the forest canopy. Thereby, we combine above-canopy eddy covariance flux measurements and forest floor chamber flux measurements (using five custom-made fully automated chambers). Both systems are connected to a quantum cascade laser absorption spectrometer (QCL, Aerodyne) and measurements are switched between three hours of above-canopy and one hour of forest floor GHG flux measurements. Using this approach, we will be able to study the full GHG budget as well as the dynamics of the individual fluxes on two vertical levels within the forest using a single instrument. The first results presented here will highlight the suitability of this promising tool for quantifying the full GHG budget of forest ecosystems.

Management impacts on forest floor and soil organic carbon in northern temperate forests of the US

Treesearch

Coeli M. Hoover

2011-01-01

The role of forests in the global carbon cycle has been the subject of a great deal of research recently, but the impact of management practices on forest soil dynamics at the stand level has received less attention. This study used six forest management experimental sites in five northern states of the US to investigate the effects of silvicultural treatments (light...

Increasing soil temperature in a northern hardwood forest: effects on elemental dynamics and primary productivity

Treesearch

Patrick J. McHale; Myron J. Mitchell; Dudley J. Raynal; Francis P. Bowles

1996-01-01

To investigate the effects of elevated soil temperatures on a forest ecosystem, heating cables were buried at a depth of 5 cm within the forest floor of a northern hardwood forest at the Huntington Wildlife Forest (Adirondack Mountains, New York). Temperature was elevated 2.5, 5.0 and 7.5?C above ambient, during May - September in both 1993 and 1994. Various aspects of...

Conversion of rainforest into agroforestry and monoculture plantation in China: Consequences for soil phosphorus forms and microbial community.

PubMed

Wang, Jinchuang; Ren, Changqi; Cheng, Hanting; Zou, Yukun; Bughio, Mansoor Ahmed; Li, Qinfen

2017-10-01

Microbial communities and their associated enzyme activities affect quantity and quality of phosphorus (P) in soils. Land use change is likely to alter microbial community structure and feedback on ecosystem structure and function. This study presents a novel assessment of mechanistic links between microbial responses to land use and shifts in the amount and quality of soil phosphorus (P). We investigated effects of the conversion of rainforests into rubber agroforests (AF), young rubber (YR), and mature rubber (MR) plantations on soil P fractions (i.e., labile P, moderately labile P, occluded P, Ca P, and residual P) in Hainan Island, Southern China. Microbial community composition and microbial enzyme were assayed to assess microbial community response to forest conversion. In addition, we also identified soil P fractions that were closely related to soil microbial and chemical properties in these forests. Conversion of forest to pure rubber plantations and agroforestry system caused a negative response in soil microorganisms and activity. The bacteria phospholipid fatty acid (PLFAs) levels in young rubber, mature rubber and rubber agroforests decreased after forest conversion, while the fungal PLFAs levels did not change. Arbuscular mycorrhizal fungi (AMF) (16:1w5c) had the highest value of 0.246μmol(gOC) -1 in natural forest, followed by rubber agroforests, mature rubber and young rubber. Level of soil acid phosphatase activity declined soon (5 years) after forest conversion compared to natural forest, but it improved in mature rubber and agroforestry system. Labile P, moderately labile P, occluded P and residual P were highest in young rubber stands, while moderately labile, occluded and residual P were lowest in rubber agroforestry system. Soil P fractions such as labile P, moderately labile P, and Ca P were the most important contributors to the variation in soil microbial community composition. We also found that soil P factions differ significantly among the four transformation systems. Soil labile P faction and its potential sources (moderately labile P, occluded P, and residual P) were positively correlated with NO 3 - , but negatively correlated with AMF, suggesting that these properties play key roles in P transformation. Our study indicated that land use had an impact on microbial community composition and functions, which consequently influenced soil phosphorus availability and cycling. Copyright © 2017 Elsevier B.V. All rights reserved.

Shifts in Geochemical Parameters and Greenhouse Gas Fluxes following Insect-Induced Tree Mortality

NASA Astrophysics Data System (ADS)

Brouillard, B.; Mikkelson, K. M.; Berryman, E.; Sharp, J.; Leonard, L.; Vega, M.

2016-12-01

Extensive insect infestations and resultant expansive tree mortality are occurring globally due in part to warmer temperatures and persistent drought. These forest disturbances are expected to cause shifts in the biogeochemical cycle due to the cessation of below ground root outputs, changes in soil microbial communities, hydrologic perturbations, and altered woody material deposits to the forest floor. To better understand biogeochemical alterations and resolve potentially conflicting findings, we studied a lodgepole pine forest recently impacted by mountain pine beetles to determine the response of subsurface geochemical parameters and gaseous flux to the effects of surrounding tree mortality. While many parameters were found to be significantly different under recently killed trees compared to their healthy counterparts (pH, soil moisture, C/N-species), notable biogeochemically relevant parameters displayed shifts that tracked with the level of surrounding tree mortality. For instance, aromatic carbon (TSUVA) and CO2 respiration were found to have an increasing linear response under grey trees as the surrounding tree mortality within an 8m radius also increased. Rather than a linear increase, ammonium and nitrogen associated bacterial communities displayed a threshold effect, not increasing until a certain level of tree mortality of approximately 40% was surpassed. Gas flux was also correlated to measured parameters in three near surface soil horizons to determine drivers of CO2 and N2O release and their interactions with biogeochemical cycles. Collectively, these results aid in elucidating the extent of forest mortality required to overcome compensatory terrestrial biogeochemical processes. A heightened understanding of these shifts will aid the scientific and resource management community through enhanced predictive understanding of greenhouse gas release or potential water quality impacts following forest disturbance.

Microbial community structure and density under different tree species in an acid forest soil (Morvan, France).

PubMed

Lejon, David P H; Chaussod, Rémi; Ranger, Jacques; Ranjard, Lionel

2005-11-01

Overexploitation of forests to increase wood production has led to the replacement of native forest by large areas of monospecific tree plantations. In the present study, the effects of different monospecific tree cover plantations on density and composition of the indigenous soil microbial community are described. The experimental site of "Breuil-Chenue" in the Morvan (France) was the site of a comparison of a similar mineral soil under Norway spruce (Picea abies), Douglas fir (Pseudotuga menziesii), oak (Quercus sessiflora), and native forest [mixed stand dominated by oak and beech (Fagus sylvatica)]. Sampling was performed during winter (February) at three depths (0-5, 5-10, and 10-15 cm). Abundance of microorganisms was estimated via microbial biomass measurements, using the fumigation-extraction method. The genetic structure of microbial communities was investigated using the bacterial- and fungal-automated ribosomal intergenic spacer analysis (B-ARISA and F-ARISA, respectively) DNA fingerprint. Only small differences in microbial biomass were observed between tree species, the highest values being recorded under oak forest and the lowest under Douglas fir. B- and F-ARISA community profiles of the different tree covers clustered separately, but noticeable similarities were observed for soils under Douglas fir and oak. A significant stratification was revealed under each tree species by a decrease in microbial biomass with increasing depths and by distinct microbial communities for each soil layer. Differences in density and community composition according to tree species and depth were related to soil physicochemical characteristics and organic matter composition.

[Effects of Different Altitudes on Soil Microbial PLFA and Enzyme Activity in Two Kinds of Forests].

PubMed

Zeng, Qing-ping; He, Bing-hui; Mao, Qiao-zhi; Wu, Yao-peng; Huang, Qi; Li, Yuan

2015-12-01

The soil microbial community is an important part in soil ecosystem, and it is sensitive to the ecological environment. Phospholipid-derived fatty acids ( PLFA ) analysis was used to examine variations in soil microbial community diversity and its influencing factors. The results showed that: there existed 48 PLFAs that were significant in the soil samples from six altitudes. The PLFAs of six altitudes with the highest contents were i16:0, 10Me17:0, 10Me18:0 TBSA. The citrus forest exhibited richer soil PLFAs distribution both in type and amount than those in masson pine. The microbial activity and functional diversity of masson pine were increased with increasing altitudes, and citrus forest gradually decreased, the PLFA content of different microbial groups in each altitude were significantly different. The richness index, Shannon-Wiener index and Pielou evenness index of masson pine in low elevation were holistically higher than those in high elevation. However, the highest richness index of citrus forest was in low altitude, the highest Shannon-Wiener index and Pielou evenness index were in high altitude. The PLFAs content of different microbial groups were closely correlated to the soil enzyme activities and environmental factors. The PLFAs of bacteria, actinomycetes, G⁻ (Gram- positive), G⁺ (Gram-negative) were positively correlated with Ure(urease) , Ive(invertase) , CAT( catalase activity) and forest type, the PLFAs of fungi was significantly correlated with Ure, Ive, CAT, the PLFAs of bacteria, fungi, actinomycetes, G⁻ , G⁺ were significantly negatively or less correlated with elevation. Ure, Ive, CAT, forest type and elevation are the pivotal factors controlling the soil microbial biomass and activities.

Representing Microbial Dormancy in Soil Decomposition Models Improves Model Performance and Reveals Key Ecosystem Controls on Microbial Activity

NASA Astrophysics Data System (ADS)

He, Y.; Yang, J.; Zhuang, Q.; Wang, G.; Liu, Y.

2014-12-01

Climate feedbacks from soils can result from environmental change and subsequent responses of plant and microbial communities and nutrient cycling. Explicit consideration of microbial life history traits and strategy may be necessary to predict climate feedbacks due to microbial physiology and community changes and their associated effect on carbon cycling. In this study, we developed an explicit microbial-enzyme decomposition model and examined model performance with and without representation of dormancy at six temperate forest sites with observed soil efflux ranged from 4 to 10 years across different forest types. We then extrapolated the model to all temperate forests in the Northern Hemisphere (25-50°N) to investigate spatial controls on microbial and soil C dynamics. Both models captured the observed soil heterotrophic respiration (RH), yet no-dormancy model consistently exhibited large seasonal amplitude and overestimation in microbial biomass. Spatially, the total RH from temperate forests based on dormancy model amounts to 6.88PgC/yr, and 7.99PgC/yr based on no-dormancy model. However, no-dormancy model notably overestimated the ratio of microbial biomass to SOC. Spatial correlation analysis revealed key controls of soil C:N ratio on the active proportion of microbial biomass, whereas local dormancy is primarily controlled by soil moisture and temperature, indicating scale-dependent environmental and biotic controls on microbial and SOC dynamics. These developments should provide essential support to modeling future soil carbon dynamics and enhance the avenue for collaboration between empirical soil experiment and modeling in the sense that more microbial physiological measurements are needed to better constrain and evaluate the models.

7. ARCHITECTURAL ELEVATIONS AND FLOOR PLANS OF OFFICE, SHEET 1 ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. ARCHITECTURAL ELEVATIONS AND FLOOR PLANS OF OFFICE, SHEET 1 OF 1, 8' X 10' NEGATIVE MADE FROM COPIES OF ORIGINAL PLANS, MAY 21, 1913; WALLOWA-WHITMAN NATIONAL FOREST SUPERVISOR'S OFFICE, BAKER CITY, OREGON - Wallowa Ranger Station, Office, 602 First Street, Wallowa, Wallowa County, OR

Changes of polarimetric scattering characteristics of ALOS PALSAR caused by the 2011 Eruption of Shinmoe-dake Volcano

NASA Astrophysics Data System (ADS)

Ohkura, Hiroshi

Full polarimetric SAR images of ALOS PALSAR of Shinmoe-dake volcano in Japan were analyzed. The volcano erupted in January, 2011 and volcano ash deposited more than 10 cm in 12 km (2) and 1 m in 2 km (2) . Two images before and after the eruption were compared based on a point view of the four-component scattering model to detect changes of polarimetric scattering characteristics. The main detected changes are as follows. Total power of the four-component scattering model decreased on a farslope after the eruption. An incident angle on a farslope is larger than the angle on a foreslope. Decrease of surface roughness due to deposited volcanic ashes makes back-scattering smaller in the area of a larger incidence angle. However the rate of the double-bounce component got higher in a forest at the foot of a mountain slope and on a plain, where the ground surface is almost horizontal and the incident angle is relatively-large. Decrease of roughness of the forest floor increases forward scattering on the floor of the larger incident angle. This increases the double-bounced scattering due to bouncing back between the forest floor and trunks which stand "perpendicularly" on the almost horizontal forest floor. The rate of the surface scattering component got higher around an area where layover occurred. In the study area, most of layovers occurred at a ridge where an incidence angle was small. Decrease of surface roughness due to the ash deposit increases the surface scattering power in the area of the small incidence angle.

Formation and loss of humic substances during decomposition in a pine forest floor

USGS Publications Warehouse

Qualls, R.G.; Takiyama, A.; Wershaw, R. L.

2003-01-01

Since twice as much C is sequestered in soils as is contained in the atmosphere, the factors controlling the decomposition rate of soil C are important to the assessment of the effects of climatic change. The formation of chemically resistant humic substances might be an important process controlling recycling of CO2 to the atmosphere. Our objectives were to measure the rate of formation and loss of humic substances during 13 yr of litter decomposition. We placed nets on the floor of a white pine (Pinus strobus) forest to separate each annual layer of litter for 13 yr and measured humic substance concentration using NaOH extraction followed by chromatographic fractionation. The humic acid fraction increased from 2.1% of the C in litterfall to 15.7% after 1 yr. On a grams per square meter (g m-2) basis the humic substance fraction increased during the first year and then declined, with a half decay time (t1/2) of 5.1 yr, which was significantly slower than the bulk litter (t1/2 = 3.9 yr). The carboxylic C concentration estimated from 13C nuclear magnetic resonance (NMR) increased in the litter over time, though total mass of carboxylic acid C in the forest floor also declined over the 13-yr period (t1/2 = 4.6 yr). While humic substances in the forest floor decomposed at a somewhat slower rate than bulk litter during Years 1 to 13, they decomposed much faster than has been calculated from 14C dating of the refractory fraction of organic matter in the mineral soil.

Busy Nights: High Seed Dispersal by Crickets in a Neotropical Forest.

PubMed

Santana, Flávia Delgado; Baccaro, Fabricio Beggiato; Costa, Flávia Regina Capellotto

2016-11-01

Among invertebrates, ants are the most abundant and probably most important seed dispersers in both temperate and tropical environments. Crickets, also abundant in tropical forests, are omnivores and commonly attracted to fruits on the forest floor. However, their capability to remove seeds has been reported only once. We compared Marantaceae seed removal by crickets and ants to assess the role of crickets as secondary seed dispersers in Amazonia. Compared with ants, crickets dispersed an equivalent number of seeds and tended to disperse larger seeds farther. However, seed removal by crickets occurs mostly at night, suggesting that removal of arillate seeds by crickets on the tropical forest floor is probably being overlooked or wrongly attributed to other invertebrate groups. One potential consequence of seed dispersal by crickets may be a change in the local spatial distribution of arillate-seed species, due to lower aggregation around ant nests.

Understory vegetation response to mechanical mastication and other fuels treatments in a ponderosa pine forest

Treesearch

Jeffrey M. Kane; J. Morgan Varner; Eric E. Knapp

2010-01-01

Questions: What influence does mechanical mastication and other fuel treatments have on: (1) canopy and forest floor response variables that influence understory plant development; (2) initial understory vegetation cover, diversity, and composition; and (3) shrub and non-native species density in a secondgrowth ponderosa pine forest....

Control of Sediment Export From The Forest Road Prism

Treesearch

Johnny M. Grace

2002-01-01

The effectiveness of four road turn-out ditch treatments (vegetation, rip-rap, sediment fences, and settling basins) in reducing sediment export to the forest floor was evaluated. These four runoff control method are commonly prescribed to control forest road runoff and sediments. The study utilized runoff samplers, runoff diversion walls, sediment filter bags, and...

Soil properties and aspen development five years after compaction and forest floor removal

Treesearch

Douglas M. Stone; John D. Elioff

1998-01-01

Forest management activities that decrease soil porosity and remove organic matter have been associated with declines in site productivity. In the northern Lake States region, research is in progress in the aspen (Populus tremuloides Michx. and P. grandidentata Michx.) forest type to determine effects of soil compaction and organic...

Interception processes during snowstorms

Treesearch

David H. Miller

1964-01-01

Four processes are identified as determining the initial interception of falling snow by forest during storms: delivery of snow particles from the airstream to the forest; true throughfall of particles to the forest floor; impaction and adhesion of particles to foliage and branches; and cohesion of particles into masses of snow. Delivery and impaction processes seem...

Temporal dynamics of phosphorus during aquatic and terrestrial litter decomposition in an alpine forest.

PubMed

Peng, Yan; Yang, Wanqin; Yue, Kai; Tan, Bo; Huang, Chunping; Xu, Zhenfeng; Ni, Xiangyin; Zhang, Li; Wu, Fuzhong

2018-06-17

Plant litter decomposition in forested soil and watershed is an important source of phosphorus (P) for plants in forest ecosystems. Understanding P dynamics during litter decomposition in forested aquatic and terrestrial ecosystems will be of great importance for better understanding nutrient cycling across forest landscape. However, despite massive studies addressing litter decomposition have been carried out, generalizations across aquatic and terrestrial ecosystems regarding the temporal dynamics of P loss during litter decomposition remain elusive. We conducted a two-year field experiment using litterbag method in both aquatic (streams and riparian zones) and terrestrial (forest floors) ecosystems in an alpine forest on the eastern Tibetan Plateau. By using multigroup comparisons of structural equation modeling (SEM) method with different litter mass-loss intervals, we explicitly assessed the direct and indirect effects of several biotic and abiotic drivers on P loss across different decomposition stages. The results suggested that (1) P concentration in decomposing litter showed similar patterns of early increase and later decrease across different species and ecosystems types; (2) P loss shared a common hierarchy of drivers across different ecosystems types, with litter chemical dynamics mainly having direct effects but environment and initial litter quality having both direct and indirect effects; (3) when assessing at the temporal scale, the effects of initial litter quality appeared to increase in late decomposition stages, while litter chemical dynamics showed consistent significant effects almost in all decomposition stages across aquatic and terrestrial ecosystems; (4) microbial diversity showed significant effects on P loss, but its effects were lower compared with other drivers. Our results highlight the importance of including spatiotemporal variations and indicate the possibility of integrating aquatic and terrestrial decomposition into a common framework for future construction of models that account for the temporal dynamics of P in decomposing litter. Copyright © 2018 Elsevier B.V. All rights reserved.

Root controls on soil microbial community structure in forest soils.

PubMed

Brant, Justin B; Myrold, David D; Sulzman, Elizabeth W

2006-07-01

We assessed microbial community composition as a function of altered above- and belowground inputs to soil in forest ecosystems of Oregon, Pennsylvania, and Hungary as part of a larger Detritus Input and Removal Treatment (DIRT) experiment. DIRT plots, which include root trenching, aboveground litter exclusion, and doubling of litter inputs, have been established in forested ecosystems in the US and Europe that vary with respect to dominant tree species, soil C content, N deposition rate, and soil type. This study used phospholipid fatty-acid (PLFA) analysis to examine changes in the soil microbial community size and composition in the mineral soil (0-10 cm) as a result of the DIRT treatments. At all sites, the PLFA profiles from the plots without roots were significantly different from all other treatments. PLFA analysis showed that the rootless plots generally contained larger quantities of actinomycete biomarkers and lower amounts of fungal biomarkers. At one of the sites in an old-growth coniferous forest, seasonal changes in PLFA profiles were also examined. Seasonal differences in soil microbial community composition were greater than treatment differences. Throughout the year, treatments without roots continued to have a different microbial community composition than the treatments with roots, although the specific PLFA biomarkers responsible for these differences varied by season. These data provide direct evidence that root C inputs exert a large control on microbial community composition in the three forested ecosystems studied.

Interactions between terrestrial mammals and the fruits of two neotropical rainforest tree species

NASA Astrophysics Data System (ADS)

Camargo-Sanabria, Angela A.; Mendoza, Eduardo

2016-05-01

Mammalian frugivory is a distinctive biotic interaction of tropical forests; however, most efforts in the Neotropics have focused on cases of animals foraging in the forest canopy, in particular primates and bats. In contrast much less is known about this interaction when it involves fruits deposited on the forest floor and terrestrial mammals. We conducted a camera-trapping survey to analyze the characteristics of the mammalian ensembles visiting fruits of Licania platypus and Pouteria sapota deposited on the forest floor in a well preserved tropical rainforest of Mexico. Both tree species produce large fruits but contrast in their population densities and fruit chemical composition. In particular, we expected that more species of terrestrial mammals would consume P. sapota fruits due to its higher pulp:seed ratio, lower availability and greater carbohydrate content. We monitored fruits at the base of 13 trees (P. sapota, n = 4 and L. platypus, n = 9) using camera-traps. We recorded 13 mammal species from which we had evidence of 8 consuming or removing fruits. These eight species accounted for 70% of the species of mammalian frugivores active in the forest floor of our study area. The ensemble of frugivores associated with L. platypus (6 spp.) was a subset of that associated with P. sapota (8 spp). Large body-sized species such as Tapirus bairdii, Pecari tajacu and Cuniculus paca were the mammals more frequently interacting with fruits of the focal species. Our results further our understanding of the characteristics of the interaction between terrestrial mammalian frugivores and large-sized fruits, helping to gain a more balanced view of its importance across different tropical forests and providing a baseline to compare against defaunated forests.

Changes in microbial community characteristics and soil organic matter with nitrogen additions in two tropical forests

Treesearch

Daniela F. Cusack; Whendee L. Silver; Margaret S. Torn; Sarah D. Burton; Mary K. Firestone

2011-01-01

Microbial communities and their associated enzyme activities affect the amount and chemical quality of carbon (C) in soils. Increasing nitrogen (N) deposition, particularly in N-rich tropical forests, is likely to change the composition and behavior of microbial communities and feed back on ecosystem structure and function. This study presents a novel assessment of...

The efficacy of salvage logging in reducing subsequent fire severity in conifer-dominated forests of Minnesota, U.S.A.

PubMed

Fraver, Shawn; Jain, Theresa; Bradford, John B; D'Amato, Anthony W; Kastendick, Doug; Palik, Brian; Shinneman, Doug; Stanovick, John

2011-09-01

Although primarily used to mitigate economic losses following disturbance, salvage logging has also been justified on the basis of reducing fire risk and fire severity; however, its ability to achieve these secondary objectives remains unclear. The patchiness resulting from a sequence of recent disturbances-blowdown, salvage logging, and wildfire-provided an excellent opportunity to assess the impacts of blowdown and salvage logging on wildfire severity. We used two fire-severity assessments (tree-crown and forest-floor characteristics) to compare post-wildfire conditions among three treatment combinations (Blowdown-Salvage-Fire, Blowdown-Fire, and Fire only). Our results suggest that salvage logging reduced the intensity (heat released) of the subsequent fire. However, its effect on severity (impact to the system) differed between the tree crowns and forest floor: tree-crown indices suggest that salvage logging decreased fire severity (albeit with modest statistical support), while forest-floor indices suggest that salvage logging increased fire severity. We attribute the latter finding to the greater exposure of mineral soil caused by logging operations; once exposed, soils are more likely to register the damaging effects of fire, even if fire intensity is not extreme. These results highlight the important distinction between fire intensity and severity when formulating post-disturbance management prescriptions.

The efficacy of salvage logging in reducing subsequent fire severity in conifer-dominated forests of Minnesota, USA

USGS Publications Warehouse

Fraver, S.; Jain, T.; Bradford, J.B.; D'Amato, A.W.; Kastendick, D.; Palik, B.; Shinneman, D.; Stanovick, J.

2011-01-01

Although primarily used to mitigate economic losses following disturbance, salvage logging has also been justified on the basis of reducing fire risk and fire severity; however, its ability to achieve these secondary objectives remains unclear. The patchiness resulting from a sequence of recent disturbances-blowdown, salvage logging, and ildfire- provided an excellent opportunity to assess the impacts of blowdown and salvage logging on wildfire severity. We used two fire-severity assessments (tree-crown and forest-floor characteristics) to compare post-wildfire conditions among three treatment combinations (Blowdown-Salvage-Fire, Blowdown-Fire, and Fire only). Our results suggest that salvage logging reduced the intensity (heat released) of the subsequent fire. However, its effect on severity (impact to the system) differed between the tree crowns and forest floor: tree-crown indices suggest that salvage logging decreased fire severity (albeit with modest statistical support), while forest-floor indices suggest that salvage logging increased fire severity. We attribute the latter finding to the greater exposure of mineral soil caused by logging operations; once exposed, soils are more likely to register the damaging effects of fire, even if fire intensity is not extreme. These results highlight the important distinction between fire intensity and severity when formulating post-disturbance management prescriptions. ?? 2011 by the Ecological Society of America.

Vine maple (Acer circinatum) clone growth and reproduction in managed and unmanaged coastal Oregon douglas-fir forests

USGS Publications Warehouse

O'Dea, Mary E.; Zasada, John C.; Tappeiner, John C.

1995-01-01

Vine maple (Acer circinatum Pursh.) clone development, expansion, and regeneration by seedling establishment were studied in 5-240 yr old managed and unmanaged Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stands in coastal Oregon. Stem length, number of stems, and crown area were all significantly (P @10 m long and basal sprouts 1-2 m long; some stems had been pinned to the forest floor by fallen trees or branches and had layered. In stands >120 yr in age, clones were often quite complex, composed of several decumbent stems each of which connected the ramets of 1-10 new aerial stems. Vine maple clone expansion occurs by the layering of long aerial stems. Over 95% of the layered stems we observed had been pinned to the forest floor by fallen debris. Unsevered stems that we artificially pinned to the forest floor initiated roots within 1 yr. Thinning may favor clonal expansion because fallen slash from thinning often causes entire clones to layer, not just individual stems. Clonal vine maple seed production and seedling establishment occurred in all stages of stand development except dense, young stands following crown closure. There were more seedlings in thinned stands than in unthinned stands and in unburned clearcuts than in burned clearcuts.

Biomass removal and its effect on productivity of an artificially regenerated forest stand in the Missouri ozarks

Treesearch

Flex Jr. Ponder

2007-01-01

Intensive harvesting, which removes a greater proportion of the forest biomass than conventional harvesting and the associated nutrients, may cause a decline in forest productivity. Planted seedling response to three biomass removal levels (1. removal of boles only=OM1, 2. all surface organic matter removed, forest floor not removed=OM2, and 3. removal of all surface...

Measuring and modeling carbon stock change estimates for US forests and uncertainties from apparent inter-annual variability

Treesearch

James E. Smith; Linda S. Heath

2015-01-01

Our approach is based on a collection of models that convert or augment the USDA Forest Inventory and Analysis program survey data to estimate all forest carbon component stocks, including live and standing dead tree aboveground and belowground biomass, forest floor (litter), down deadwood, and soil organic carbon, for each inventory plot. The data, which include...

Height is more important than light in determining leaf morphology in a tropical forest

Treesearch

Molly A. Cavaleri; Steven F. Oberbauer; David B. Clark; Deborah A. Clark; Michael G. Ryan

2010-01-01

Both within and between species, leaf physiological parameters are strongly related to leaf dry mass per area (LMA, g/m2), which has been found to increase from forest floor to canopy top in every forest where it has been measured. Although vertical LMA gradients in forests have historically been attributed to a direct phenotypic response to light, an increasing number...

Effects of reforestation on ammonia-oxidizing microbial community composition and abundance in subtropical acidic forest soils.

PubMed

Wu, Ruo-Nan; Meng, Han; Wang, Yong-Feng; Gu, Ji-Dong

2018-06-01

Forest ecosystems have great ecological values in mitigation of climate change and protection of biodiversity of flora and fauna; re-forestry is commonly used to enhance the sequestration of atmospheric CO 2 into forest storage biomass. Therefore, seasonal and spatial dynamics of the major microbial players in nitrification, ammonia-oxidizing archaea (AOA) and bacteria (AOB), in acidic soils of young and matured revegetated forests were investigated to elucidate the changes of microbial communities during forest restoration, and compared to delineate the patterns of community shifts under the influences of environmental factors. AOA were more abundant than AOB in both young and matured revegetated forest soils in both summer and winter seasons. In summer, however, the abundance of amoA-AOA decreased remarkably (p < 0.01), ranging from 1.90 (± 0.07) × 10 8 copies per gram dry soil in matured forest to 5.04 (± 0.43) × 10 8 copies per gram dry soil in young forest, and amoA-AOB was below detection limits to obtain any meaningful values. Moreover, exchangeable Al 3+ and organic matter were found to regulate the physiologically functional nitrifiers, especially AOA abundance in acidic forest soils. AOB community in winter showed stronger correlation with the restoration status of revegetated forests and AOA community dominated by Nitrosotalea devanaterra, in contrast, was more sensitive to the seasonal and spatial variations of environmental factors. These results enrich the current knowledge of nitrification during re-forestry and provide valuable information to developmental status of revegetated forests for management through microbial analysis.

5. ARCHITECTURAL ELEVATIONS AND FLOOR PLANS OF GARAGE, SHEET 1 ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. ARCHITECTURAL ELEVATIONS AND FLOOR PLANS OF GARAGE, SHEET 1 OF 1, 8' X 10' NEGATIVE AND PRINT MADE FROM COPIES OF ORIGINAL PLANS, MAY 15, 1936, WALLOWA-WHITMAN NATIONAL FOREST SUPERVISOR'S, OFFICE, BAKER CITY, OREGON. - Wallowa Ranger Station, Garage, 602 First Street, Wallowa, Wallowa County, OR

5. ARCHITECTURAL ELEVATIONS AND FLOOR PLAN OF GAS HOUSE, SHEET ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. ARCHITECTURAL ELEVATIONS AND FLOOR PLAN OF GAS HOUSE, SHEET 1 OF 1, 8' X 10' NEGATIVE AND PRINT MADE FROM COPIES OF ORIGINAL PLANS, MAY 18, 1936, WALLOWA-WHITMAN NATIONAL FOREST SUPERVISOR'S, OFFICE, BAKER CITY, OREGON. - Wallowa Ranger Station, Gas House, 602 First Street, Wallowa, Wallowa County, OR

8. FLOOR PLANS OF FIRE EQUIPMENT BUILDING, SHEET 2 OF ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. FLOOR PLANS OF FIRE EQUIPMENT BUILDING, SHEET 2 OF 2, 8' X 10' NEGATIVE AND PRINT MADE FROM COPIES OF ORIGINAL PLANS, MAY 6, 1936, WALLOWA-WHITMAN NATIONAL FOREST SUPERVISOR'S OFFICE, BAKER CITY, OREGON. - Wallowa Ranger Station, Fire Equipment Building, 602 First Street, Wallowa, Wallowa County, OR

Are variations in heterotrophic soil respiration related to changes in substrate availability and microbial biomass carbon in the subtropical forests?

PubMed

Wei, Hui; Chen, Xiaomei; Xiao, Guoliang; Guenet, Bertrand; Vicca, Sara; Shen, Weijun

2015-12-16

Soil temperature and moisture are widely-recognized controlling factors on heterotrophic soil respiration (Rh), although they often explain only a portion of Rh variability. How other soil physicochemical and microbial properties may contribute to Rh variability has been less studied. We conducted field measurements on Rh half-monthly and associated soil properties monthly for two years in four subtropical forests of southern China to assess influences of carbon availability and microbial properties on Rh. Rh in coniferous forest was significantly lower than that in the other three broadleaf species-dominated forests and exhibited obvious seasonal variations in the four forests (P < 0.05). Temperature was the primary factor influencing the seasonal variability of Rh while moisture was not in these humid subtropical forests. The quantity and decomposability of dissolved organic carbon (DOC) were significantly important to Rh variations, but the effect of DOC content on Rh was confounded with temperature, as revealed by partial mantel test. Microbial biomass carbon (MBC) was significantly related to Rh variations across forests during the warm season (P = 0.043). Our results suggest that DOC and MBC may be important when predicting Rh under some conditions, and highlight the complexity by mutual effects of them with environmental factors on Rh variations.

Soil Microbial Biomass, Basal Respiration and Enzyme Activity of Main Forest Types in the Qinling Mountains

PubMed Central

Cheng, Fei; Peng, Xiaobang; Zhao, Peng; Yuan, Jie; Zhong, Chonggao; Cheng, Yalong; Cui, Cui; Zhang, Shuoxin

2013-01-01

Different forest types exert essential impacts on soil physical-chemical characteristics by dominant tree species producing diverse litters and root exudates, thereby further regulating size and activity of soil microbial communities. However, the study accuracy is usually restricted by differences in climate, soil type and forest age. Our objective is to precisely quantify soil microbial biomass, basal respiration and enzyme activity of five natural secondary forest (NSF) types with the same stand age and soil type in a small climate region and to evaluate relationship between soil microbial and physical-chemical characters. We determined soil physical-chemical indices and used the chloroform fumigation-extraction method, alkali absorption method and titration or colorimetry to obtain the microbial data. Our results showed that soil physical-chemical characters remarkably differed among the NSFs. Microbial biomass carbon (Cmic) was the highest in wilson spruce soils, while microbial biomass nitrogen (Nmic) was the highest in sharptooth oak soils. Moreover, the highest basal respiration was found in the spruce soils, but mixed, Chinese pine and spruce stands exhibited a higher soil qCO2. The spruce soils had the highest Cmic/Nmic ratio, the greatest Nmic/TN and Cmic/Corg ratios were found in the oak soils. Additionally, the spruce soils had the maximum invertase activity and the minimum urease and catalase activities, but the maximum urease and catalase activities were found in the mixed stand. The Pearson correlation and principle component analyses revealed that the soils of spruce and oak stands obviously discriminated from other NSFs, whereas the others were similar. This suggested that the forest types affected soil microbial properties significantly due to differences in soil physical-chemical features. PMID:23840671

Prolonged Effect of Severe Wildfires on Mercury and Other Volatiles in Forest Soils of the Lake Superior Region, USA

NASA Astrophysics Data System (ADS)

Cannon, W. F.; Woodruff, L. G.

2003-12-01

Soils in Isle Royale National Park, Michigan and Voyageurs National Park, Minnesota show spatial patterns of depletion of total Hg, organic C, Se, total S, P, and Pb within areas of severe, stand-replacing wildfires that burned in 1936, approximately 65 years prior to our current study. The fires burned during a regional drought, were of high severity, and likely consumed a high percentage of organic forest-floor material (O-horizon). A "fire factor" is defined by positive correlations among Hg, C, Se, S, P, and Pb. A factor score for this six-element grouping derived from factor analysis was assigned to each sample. The scores show a high spatial correlation with the footprint of the 1936 fires in both parks, particularly for A-horizon soils. Because many of these elements are volatile, and are highly correlated with soil organic matter, observed depletions likely represent instantaneous atmospheric release during combustion of O-horizon soils coupled with decades-long reduction of organic matter on the forest floor and near-surface soils. Nearly complete combustion of the modern O-horizon would release roughly 1 mg Hg/m2 from the forest floor. Decades-long disturbance resulting from destruction of mature forests and gradual regrowth following fire also play an important role in Hg cycling. Destruction of a mature forest results in decreased deposition of Hg from litterfall as well as throughfall, which contributes Hg by wash-off of dry deposited Hg from foliar surfaces. Hg in forest soils may follow a fire-dependent cycle in which sudden Hg loss during fire is followed by a period of continued Hg loss as evasion exceeds sequestration in the early stand-replacement stage, finally to resume gradual buildup in later stages of forest regrowth. In the Lake Superior region this cycle exceeds 65 years in duration and is of the same magnitude as the fire return interval for this region. Forests that are controlled by fire-induced cycles of stand replacement may also be in continuous cycles of Hg sequestration and emission. Fire history appears to be a major determinant in the amount of Hg stored in forest soils. Fire almost certainly releases Hg to the atmosphere as forest floor material is burned and thus contributes to atmospheric Hg loads. Fire also appears to cleanse burned areas of Hg both by the atmospheric release during combustion and longer-term release during post-fire forest reorganization. Fire cleansing appears to persist for decades after severe fires and may ameliorate Hg contamination of aquatic food webs by decreasing the soil Hg load of burned watersheds.

Methane Emissions from Upland Forests

NASA Astrophysics Data System (ADS)

Megonigal, Patrick; Pitz, Scott; Wang, Zhi-Ping

2016-04-01

Global budgets ascribe 4-10% of atmospheric methane sinks to upland soils and assume that soils are the sole surface for methane exchange between upland forests and the atmosphere. The dogma that upland forests are uniformly atmospheric methane sinks was challenged a decade ago by the discovery of abiotic methane production from plant tissue. Subsequently a variety of relatively cryptic microbial and non-microbial methane sources have been proposed that have the potential to emit methane in upland forests. Despite the accumulating evidence of potential methane sources, there are few data demonstrating actual emissions of methane from a plant surface in an upland forest. We report direct observations of methane emissions from upland tree stems in two temperate forests. Stem methane emissions were observed from several tree species that dominate a forest located on the mid-Atlantic coast of North America (Maryland, USA). Stem emissions occurred throughout the growing season while soils adjacent to the trees simultaneously consumed methane. Scaling fluxes by stem surface area suggested the forest was a net methane source during a wet period in June, and that stem emissions offset 5% of the soil methane sink on an annual basis. High frequency measurements revealed diurnal cycles in stem methane emission rates, pointing to soils as the methane source and transpiration as the most likely pathway for gas transport. Similar observations were made in an upland forest in Beijing, China. However, in this case the evidence suggested the methane was not produced in soils, but in the heartwood by microbial or non-microbial processes. These data challenge the concept that forests are uniform sinks of methane, and suggest that upland forests are smaller methane sinks than previously estimated due to stem emissions. Tree emissions may be particularly important in upland tropical forests characterized by high rainfall and transpiration.

Divergent Responses of Forest Soil Microbial Communities under Elevated CO 2 in Different Depths of Upper Soil Layers

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

Yu, Hao; He, Zhili; Wang, Aijie

Numerous studies have shown that the continuous increase of atmosphere CO 2 concentrations may have profound effects on the forest ecosystem and its functions. However, little is known about the response of belowground soil microbial communities under elevated atmospheric CO 2 (eCO 2) at different soil depth profiles in forest ecosystems. In this paper, we examined soil microbial communities at two soil depths (0 to 5 cm and 5 to 15 cm) after a 10-year eCO 2 exposure using a high-throughput functional gene microarray (GeoChip). The results showed that eCO 2 significantly shifted the compositions, including phylogenetic and functional genemore » structures, of soil microbial communities at both soil depths. Key functional genes, including those involved in carbon degradation and fixation, methane metabolism, denitrification, ammonification, and nitrogen fixation, were stimulated under eCO 2 at both soil depths, although the stimulation effect of eCO 2 on these functional markers was greater at the soil depth of 0 to 5 cm than of 5 to 15 cm. Moreover, a canonical correspondence analysis suggested that NO 3-N, total nitrogen (TN), total carbon (TC), and leaf litter were significantly correlated with the composition of the whole microbial community. This study revealed a positive feedback of eCO 2 in forest soil microbial communities, which may provide new insight for a further understanding of forest ecosystem responses to global CO 2 increases. The concentration of atmospheric carbon dioxide (CO 2) has continuously been increasing since the industrial revolution. Understanding the response of soil microbial communities to elevated atmospheric CO 2 (eCO 2) is important for predicting the contribution of the forest ecosystem to global atmospheric change. This study analyzed the effect of eCO 2 on microbial communities at two soil depths (0 to 5 cm and 5 to 15 cm) in a forest ecosystem. Our findings suggest that the compositional and functional structures of microbial communities shifted under eCO 2 at both soil depths. Finally, more functional genes involved in carbon, nitrogen, and phosphorus cycling were stimulated under eCO 2 at the soil depth of 0 to 5 cm than at the depth of 5 to 15 cm.« less

Divergent Responses of Forest Soil Microbial Communities under Elevated CO 2 in Different Depths of Upper Soil Layers

DOE PAGES

Yu, Hao; He, Zhili; Wang, Aijie; ...

2017-10-27

Numerous studies have shown that the continuous increase of atmosphere CO 2 concentrations may have profound effects on the forest ecosystem and its functions. However, little is known about the response of belowground soil microbial communities under elevated atmospheric CO 2 (eCO 2) at different soil depth profiles in forest ecosystems. In this paper, we examined soil microbial communities at two soil depths (0 to 5 cm and 5 to 15 cm) after a 10-year eCO 2 exposure using a high-throughput functional gene microarray (GeoChip). The results showed that eCO 2 significantly shifted the compositions, including phylogenetic and functional genemore » structures, of soil microbial communities at both soil depths. Key functional genes, including those involved in carbon degradation and fixation, methane metabolism, denitrification, ammonification, and nitrogen fixation, were stimulated under eCO 2 at both soil depths, although the stimulation effect of eCO 2 on these functional markers was greater at the soil depth of 0 to 5 cm than of 5 to 15 cm. Moreover, a canonical correspondence analysis suggested that NO 3-N, total nitrogen (TN), total carbon (TC), and leaf litter were significantly correlated with the composition of the whole microbial community. This study revealed a positive feedback of eCO 2 in forest soil microbial communities, which may provide new insight for a further understanding of forest ecosystem responses to global CO 2 increases. The concentration of atmospheric carbon dioxide (CO 2) has continuously been increasing since the industrial revolution. Understanding the response of soil microbial communities to elevated atmospheric CO 2 (eCO 2) is important for predicting the contribution of the forest ecosystem to global atmospheric change. This study analyzed the effect of eCO 2 on microbial communities at two soil depths (0 to 5 cm and 5 to 15 cm) in a forest ecosystem. Our findings suggest that the compositional and functional structures of microbial communities shifted under eCO 2 at both soil depths. Finally, more functional genes involved in carbon, nitrogen, and phosphorus cycling were stimulated under eCO 2 at the soil depth of 0 to 5 cm than at the depth of 5 to 15 cm.« less

Divergent Responses of Forest Soil Microbial Communities under Elevated CO2 in Different Depths of Upper Soil Layers.

PubMed

Yu, Hao; He, Zhili; Wang, Aijie; Xie, Jianping; Wu, Liyou; Van Nostrand, Joy D; Jin, Decai; Shao, Zhimin; Schadt, Christopher W; Zhou, Jizhong; Deng, Ye

2018-01-01

Numerous studies have shown that the continuous increase of atmosphere CO 2 concentrations may have profound effects on the forest ecosystem and its functions. However, little is known about the response of belowground soil microbial communities under elevated atmospheric CO 2 (eCO 2 ) at different soil depth profiles in forest ecosystems. Here, we examined soil microbial communities at two soil depths (0 to 5 cm and 5 to 15 cm) after a 10-year eCO 2 exposure using a high-throughput functional gene microarray (GeoChip). The results showed that eCO 2 significantly shifted the compositions, including phylogenetic and functional gene structures, of soil microbial communities at both soil depths. Key functional genes, including those involved in carbon degradation and fixation, methane metabolism, denitrification, ammonification, and nitrogen fixation, were stimulated under eCO 2 at both soil depths, although the stimulation effect of eCO 2 on these functional markers was greater at the soil depth of 0 to 5 cm than of 5 to 15 cm. Moreover, a canonical correspondence analysis suggested that NO 3 -N, total nitrogen (TN), total carbon (TC), and leaf litter were significantly correlated with the composition of the whole microbial community. This study revealed a positive feedback of eCO 2 in forest soil microbial communities, which may provide new insight for a further understanding of forest ecosystem responses to global CO 2 increases. IMPORTANCE The concentration of atmospheric carbon dioxide (CO 2 ) has continuously been increasing since the industrial revolution. Understanding the response of soil microbial communities to elevated atmospheric CO 2 (eCO 2 ) is important for predicting the contribution of the forest ecosystem to global atmospheric change. This study analyzed the effect of eCO 2 on microbial communities at two soil depths (0 to 5 cm and 5 to 15 cm) in a forest ecosystem. Our findings suggest that the compositional and functional structures of microbial communities shifted under eCO 2 at both soil depths. More functional genes involved in carbon, nitrogen, and phosphorus cycling were stimulated under eCO 2 at the soil depth of 0 to 5 cm than at the depth of 5 to 15 cm. Copyright © 2017 American Society for Microbiology.

Predator contributions to belowground responses to warming

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

Maran, A. M.; Pelini, S. L.

Identifying the factors that control soil CO 2 emissions will improve our ability to predict the magnitude of climate change–soil ecosystem feedbacks. Despite the integral role of invertebrates in belowground systems, they are excluded from climate change models. Soil invertebrates have consumptive and nonconsumptive effects on microbes, whose respiration accounts for nearly half of soil CO 2 emissions. By altering the behavior and abundance of invertebrates that interact with microbes, invertebrate predators may have indirect effects on soil respiration. We examined the effects of a generalist arthropod predator on belowground respiration under different warming scenarios. Based on research suggesting invertebratesmore » may mediate soil CO 2 emission responses to warming, we predicted that predator presence would result in increased emissions by negatively affecting these invertebrates. We altered the presence of wolf spiders ( Pardosa spp.) in mesocosms containing a forest floor community. To simulate warming, we placed mesocosms of each treatment in ten open-top warming chambers ranging from 1.5° to 5.5°C above ambient at Harvard Forest, Massachusetts, USA. As expected, CO 2 emissions increased under warming and we found an interactive effect of predator presence and warming, although the effect was not consistent through time. The interaction between predator presence and warming was the inverse of our predictions: Mesocosms with predators had lower respiration at higher levels of warming than those without predators. Carbon dioxide emissions were not significantly associated with microbial biomass. Here, we did not find evidence of consumptive effects of predators on the invertebrate community, suggesting that predator presence mediates response of microbial respiration to warming through nonconsumptive means. In our system, we found a significant interaction between warming and predator presence that warrants further research into mechanism and generality of this pattern to other systems.« less

Predator contributions to belowground responses to warming

DOE PAGES

Maran, A. M.; Pelini, S. L.

2016-09-26

Identifying the factors that control soil CO 2 emissions will improve our ability to predict the magnitude of climate change–soil ecosystem feedbacks. Despite the integral role of invertebrates in belowground systems, they are excluded from climate change models. Soil invertebrates have consumptive and nonconsumptive effects on microbes, whose respiration accounts for nearly half of soil CO 2 emissions. By altering the behavior and abundance of invertebrates that interact with microbes, invertebrate predators may have indirect effects on soil respiration. We examined the effects of a generalist arthropod predator on belowground respiration under different warming scenarios. Based on research suggesting invertebratesmore » may mediate soil CO 2 emission responses to warming, we predicted that predator presence would result in increased emissions by negatively affecting these invertebrates. We altered the presence of wolf spiders ( Pardosa spp.) in mesocosms containing a forest floor community. To simulate warming, we placed mesocosms of each treatment in ten open-top warming chambers ranging from 1.5° to 5.5°C above ambient at Harvard Forest, Massachusetts, USA. As expected, CO 2 emissions increased under warming and we found an interactive effect of predator presence and warming, although the effect was not consistent through time. The interaction between predator presence and warming was the inverse of our predictions: Mesocosms with predators had lower respiration at higher levels of warming than those without predators. Carbon dioxide emissions were not significantly associated with microbial biomass. Here, we did not find evidence of consumptive effects of predators on the invertebrate community, suggesting that predator presence mediates response of microbial respiration to warming through nonconsumptive means. In our system, we found a significant interaction between warming and predator presence that warrants further research into mechanism and generality of this pattern to other systems.« less

Temporal Dynamics of Abiotic and Biotic Factors on Leaf Litter of Three Plant Species in Relation to Decomposition Rate along a Subalpine Elevation Gradient

PubMed Central

Zhu, Jianxiao; Yang, Wanqin; He, Xinhua

2013-01-01

Relationships between abiotic (soil temperature and number of freeze-thaw cycles) or biotic factors (chemical elements, microbial biomass, extracellular enzymes, and decomposer communities in litter) and litter decomposition rates were investigated over two years in subalpine forests close to the Qinghai-Tibet Plateau in China. Litterbags with senescent birch, fir, and spruce leaves were placed on the forest floor at 2,704 m, 3,023 m, 3,298 m, and 3,582 m elevation. Results showed that the decomposition rate positively correlated with soil mean temperature during the plant growing season, and with the number of soil freeze-thaw cycles during the winter. Concentrations of soluble nitrogen (N), phosphorus (P) and potassium (K) had positive effects but C:N and lignin:N ratios had negative effects on the decomposition rate (k), especially during the winter. Meanwhile, microbial biomass carbon (MBC), N (MBN), and P (MBP) were positively correlated with k values during the first growing season. These biotic factors accounted for 60.0% and 56.4% of the variation in decomposition rate during the winter and the growing season in the first year, respectively. Specifically, litter chemistry (C, N, P, K, lignin, C:N and lignin:N ratio) independently explained 29.6% and 13.3%, and the microbe-related factors (MBC, MBN, MBP, bacterial and fungal biomass, sucrase and ACP activity) explained 22.9% and 34.9% during the first winter and the first growing season, respectively. We conclude that frequent freeze-thaw cycles and litter chemical properties determine the winter decomposition while microbe-related factors play more important roles in determining decomposition in the subsequent growing season. PMID:23620803

Direct effects of temperature on forest nitrogen cycling revealed through analysis of long-term watershed records

Treesearch

E.N. Jack Brookshire; Stefan Gerber; Jackson R. Webster; James M. Vose; Wayne T. Swank

2010-01-01

The microbial conversion of organic nitrogen (N) to plant available forms is a critical determinant of plant growth and carbon sequestration in forests worldwide. In temperate zones, microbial activity is coupled to variations in temperature, yet at the ecosystem level, microbial N mineralization seems to play a minor role in determining patterns of N loss. Rather, N...

Variation in carbon storage and its distribution by stand age and forest type in boreal and temperate forests in northeastern China.

PubMed

Wei, Yawei; Li, Maihe; Chen, Hua; Lewis, Bernard J; Yu, Dapao; Zhou, Li; Zhou, Wangming; Fang, Xiangmin; Zhao, Wei; Dai, Limin

2013-01-01

The northeastern forest region of China is an important component of total temperate and boreal forests in the northern hemisphere. But how carbon (C) pool size and distribution varies among tree, understory, forest floor and soil components, and across stand ages remains unclear. To address this knowledge gap, we selected three major temperate and two major boreal forest types in northeastern (NE) China. Within both forest zones, we focused on four stand age classes (young, mid-aged, mature and over-mature). Results showed that total C storage was greater in temperate than in boreal forests, and greater in older than in younger stands. Tree biomass C was the main C component, and its contribution to the total forest C storage increased with increasing stand age. It ranged from 27.7% in young to 62.8% in over-mature stands in boreal forests and from 26.5% in young to 72.8% in over-mature stands in temperate forests. Results from both forest zones thus confirm the large biomass C storage capacity of old-growth forests. Tree biomass C was influenced by forest zone, stand age, and forest type. Soil C contribution to total forest C storage ranged from 62.5% in young to 30.1% in over-mature stands in boreal and from 70.1% in young to 26.0% in over-mature in temperate forests. Thus soil C storage is a major C pool in forests of NE China. On the other hand, understory and forest floor C jointly contained less than 13% and <5%, in boreal and temperate forests respectively, and thus play a minor role in total forest C storage in NE China.

Variation in Carbon Storage and Its Distribution by Stand Age and Forest Type in Boreal and Temperate Forests in Northeastern China

PubMed Central

Wei, Yawei; Li, Maihe; Chen, Hua; Lewis, Bernard J.; Yu, Dapao; Zhou, Li; Zhou, Wangming; Fang, Xiangmin; Zhao, Wei; Dai, Limin

2013-01-01

The northeastern forest region of China is an important component of total temperate and boreal forests in the northern hemisphere. But how carbon (C) pool size and distribution varies among tree, understory, forest floor and soil components, and across stand ages remains unclear. To address this knowledge gap, we selected three major temperate and two major boreal forest types in northeastern (NE) China. Within both forest zones, we focused on four stand age classes (young, mid-aged, mature and over-mature). Results showed that total C storage was greater in temperate than in boreal forests, and greater in older than in younger stands. Tree biomass C was the main C component, and its contribution to the total forest C storage increased with increasing stand age. It ranged from 27.7% in young to 62.8% in over-mature stands in boreal forests and from 26.5% in young to 72.8% in over-mature stands in temperate forests. Results from both forest zones thus confirm the large biomass C storage capacity of old-growth forests. Tree biomass C was influenced by forest zone, stand age, and forest type. Soil C contribution to total forest C storage ranged from 62.5% in young to 30.1% in over-mature stands in boreal and from 70.1% in young to 26.0% in over-mature in temperate forests. Thus soil C storage is a major C pool in forests of NE China. On the other hand, understory and forest floor C jointly contained less than 13% and <5%, in boreal and temperate forests respectively, and thus play a minor role in total forest C storage in NE China. PMID:23977252

Vertical distribution of radiocesium in coniferous forest soil after the Fukushima nuclear power plant accident.

PubMed

Teramage, Mengistu T; Onda, Yuichi; Patin, Jeremy; Kato, Hiroaki; Gomi, Takashi; Nam, Sooyoun

2014-11-01

This study deals with the description of the vertical distribution of radiocaesium ((137)Cs and (134)Cs) in a representative coniferous forest soil, investigated 10 months after the Fukushima radioactive fallout. During soil sampling, the forest floor components (understory plants, litter (Ol-) and fermented layers (Of)) were collected and treated separately. The results indicate that radiocesium is concentrated in the forest floor, and high radiocesium transfer factor observed in the undergrowth plants (3.3). This made the forest floor an active exchanging interphase for radiocesium. The raw organic layer (Ol + Of) holds 52% (5.3 kBq m(-2)) of the Fukushima-derived and 25% (0.7 kBq m(-2)) of the pre-Fukushima (137)Cs at the time of the soil sampling. Including the pre-Fukushima (137)Cs, 99% of the total soil inventory was in the upper 10 cm, in which the organic matter (OM) content was greater than 10%, suggesting the subsequent distribution most likely depends on the OM turnover. However, the small fraction of the Fukushima-derived (137)Cs at a depth of 16 cm is most likely due to the infiltration of radiocesium-circumscribed rainwater during the fallout before that selective adsorption prevails and reduces the migration of soluble (137)Cs. The values of the depth distribution parameters revealed that the distribution of the Fukushima-derived (137)Cs was somewhat rapid. Copyright © 2014 Elsevier Ltd. All rights reserved.

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.

How appetizing is the dissolved organic matter (DOM) trees lose during rainfall?

NASA Astrophysics Data System (ADS)

Howard, D.; Van Stan, J. T., II; Whitetree, A.; Zhu, L.; Stubbins, A.

2017-12-01

Dissolved organic carbon (DOC) is the chemical backbone of dissolved organic matter (DOM), which is important because it drives many processes in soils and waterways. Current DOC work has paid little attention to interactions between rain and plant canopies, where rainfall is partitioned into throughfall and stemflow. Even less DOC research has investigated the effect of arboreal epiphytes on throughfall and stemflow DOC. The purpose of this study is twofold: (1) assess the degree and timing of DOC consumption by microbial communities (biolability) in throughfall and stemflow, and (2) determine whether the presence of arboreal epiphytes in the canopy affect DOC biolability. Biolability of stemflow and throughfall DOC from Juniperus virginiana (cedar) was determined by incubating samples for 14 days. Throughfall and stemflow DOC was highly biolabile with DOC concentrations decreasing by 30-60%. Throughfall DOC was more biolabile than stemflow DOC. DOC in both throughfall and stemflow from epiphyte-covered cedars was less biolabile than DOC from trees without epiphytes. The high biolability of tree-derived DOC indicates that its supply provides carbon substrates to the microbial community at the forest floor, in soils and the rhizosphere. Epiphytes appear to be important in determining the biolability of DOC and therefore the size of this carbon subsidy to the soil ecosystem.

Monte Carlo approaches to sampling forested tracts with lines or points

Treesearch

Harry T. Valentine; Jeffrey H. Gove; Timothy G. Gregoire

2001-01-01

Several line- and point-based sampling methods can be employed to estimate the aggregate dimensions of trees standing on a forested tract or pieces of coarse woody debris lying on the forest floor. Line methods include line intersect sampling, horizontal line sampling, and transect relascope sampling; point methods include variable- and fixed-radius plot sampling, and...

A Circular-Impact Sampler for Forest Litter

Treesearch

Stephen S. Sackett

1971-01-01

Sampling the forest floor to determine litter weight is a tedious, time-consuming job. A new device has been designed and tested at the Southern Forest Fire Laboratory that eliminates many of the past sampling problems. The sampler has been fabricated in two sizes (6- and 12-inch diameters), and these are comparable in accuracy and sampling intensity. This Note...

Forest-floor disturbance reduces chipmunk (Tamias spp.) abundance two years after variable-retention harvest of Pacific Northwestern forests

Treesearch

Randall J. Wilk; Timothy B. Harrington; Robert A. Gitzen; Chris C. Maguire

2015-01-01

We evaluated the two-year effects of variable-retention harvest on chipmunk (Tamias spp.) abundance (N^) and habitat in mature coniferous forests in western Oregon and Washington because wildlife responses to density/pattern of retained trees remain largely unknown. In a randomized complete-block design, six...

Impacts of timber harvesting on soil organic matter, nitrogen, productivity, and health of inland northwest forests

Treesearch

M. F. Jurgensen; A. E. Harvey; R. T. Graham; D. S. Page-Dumroese; J. R. Tonn; M. J. Larsen; T. B. Jain

1997-01-01

Soil organic components are important factors in the health and productivity of Inland Northwest forests. Timber harvesting and extensive site preparation (piling, windrowing, or scalping) reduces the amount of surface organic material (woody residues and forest floor layers) over large areas. Some wildfires and severe prescribed burns can have similar consequences....

Nutritional hotspots and the secret life of forests

Treesearch

Jane Smith; Laurel Kluber; Noreen Parks

2014-01-01

The floor of a Douglas-fir forest may be rich in organic matter, but nutrients essential to plant growth are locked within the decomposing needles, leaves, and fallen wood. Before nitrogen, phosphorus, and other nutrients can be cycled back through the forest system, they need to be further broken down into forms accessible to plants. Understanding how nutrients become...

Infiltration, erosion, and vegetation recovery following road obliteration

Treesearch

R. B. Foltz; H. Rhee; K. A. Yanosek

2007-01-01

Forest roads are obliterated to lower the risks of surface erosion and mass failures. One purpose of the road obliteration is to return the compacted forest roads to productive pre-road conditions, i.e., a forest floor with high infiltration capacity, low interrill erodibility, and high vegetation ground cover. It is important to know how these characteristics recover...

Development and use of a commercial-scale biochar spreader

Treesearch

Deborah S. Page-Dumroese; Nathaniel M. Anderson; Keith N. Windell; Karl Englund; Kevin Jump

2016-01-01

Applying biochar to forest sites can be problematic and costly because of the need to keep the forest floor as undisturbed as possible during and after harvest operations. The Missoula Technology and Development Center of the U.S. Forest Service, working with Rocky Mountain Research Station scientists, developed and tested a high-capacity biochar spreader that can be...

Forest Floor Decomposition Following Hurricane Litter Inputs in Several Puerto Rican Forests

Treesearch

Rebecca Ostertag; Frederick N. Scatena; Whendee L. Silver

2003-01-01

Hurricanes affect ecosystem processes by altering resource availability and heterogeneity, but the spatial and temporal signatures of these events on biomass and nutrient cycling processes are not well understood. We examined mass and nutrient inputs of hurricane-derived litter in six tropical forests spanning three life zones in northeastern Puerto Rico after the...

Quantifying the effect of fuel reduction treatments on fire behavior in boreal forests

Treesearch

B.W. Butler; R.D. Ottmar; T.S. Rupp; R. Jandt; E. Miller; K. Howard; R. Schmoll; S. Theisen; R.E. Vihnanek; D. Jimenez

2013-01-01

Mechanical (e.g., shearblading) and manual (e.g., thinning) fuel treatments have become the preferred strategy of many fire managers and agencies for reducing fire hazard in boreal forests. This study attempts to characterize the effectiveness of four fuel treatments through direct measurement of fire intensity and forest floor consumption during a single prescribed...

A case study of nitrogen saturation in western U.S. forests

Treesearch

Mark E. Fenn; Mark A. Poth

2001-01-01

Virtually complete nitrification of the available ammonium in soil and nitrification activity in the forest floor are important factors predisposing forests in the San Bernardino Mountains of southern California to nitrogen (N) saturation. As a result, inorganic N in the soil solution is dominated by nitrate. High nitrification rates also generate elevated nitric oxide...

Microbial activity in the profiles of gray forest soil and chernozems

NASA Astrophysics Data System (ADS)

Susyan, E. A.; Rybyanets, D. S.; Ananyeva, N. D.

2006-08-01

Soil samples were taken from the profiles of a gray forest soil (under a forest) and southern chernozems of different textures under meadow vegetation. The microbial biomass (MB) was determined by the method of substrate-induced respiration; the basal respiration (BR) and the population density of microorganisms on nutrient media of different composition were also determined in the samples. The microbial metabolic quotient ( qCO2 = BR/MB) and the portion of microbial carbon (C mic) in C org were calculated. The MB and BR values were shown to decrease down the soil profiles. About 57% of the total MB in the entire soil profile was concentrated in the layer of 0-24 cm of the gray forest soil. The MB in the C horizon of chernozems was approximately two times lower than the MB in the A horizon of these soils. The correlation was found between the MB and the C org ( r = 0.99) and between the MB and the clay content ( r = 0.89) in the profile of the gray forest soil. The C mic/C org ratio in the gray forest soil and in the chernozems comprised 2.3-6.6 and 1.2-9.6%, respectively. The qCO2 value increased with the depth. The microbial community in the lower layers of the gray forest soil was dominated (88-96%) by oligotrophic microorganisms (grown on soil agar); in the upper 5 cm, these microorganisms comprised only 50% of the total amount of microorganisms grown on three media.

Changes in canopy processes following whole-forest canopy nitrogen fertilization of a mature spruce-hemlock forest

Treesearch

E. Gaige; D.B. Dail; D.Y. Hollinger; E.A. Davidson; I.J. Fernandez; H. Sievering; A. White; W. Halteman

2007-01-01

Most experimental additions of nitrogen to forest ecosystems apply the N to the forest floor, bypassing important processes taking place in the canopy, including canopy retention of N and/or conversion of N from one form to another. To quantify these processes, we carried out a large-scale experiment and determined the fate of nitrogen applied directly to a mature...

Variations in canopy and litter interception across a forest chronosequence in the southern Appalachian Mountains

Treesearch

Steven T. Brantley; Paul V. Bolstad; Stephanie H. Laseter; A. Christopher Oishi; Kimberly A. Novick; Chelcy F. Miniat

2016-01-01

Variations in evapotranspiration (ET) have been well documented across a variety of forest types and climates in recent decades; however, most of these data have focused on mature, secondgrowth stands. Here we present data on two important fluxes of water, canopy interception (Ic) and forest floor litter interception (Iff), across a chronosequence of forest age in the...

Pinus sylvestris as a missing source of nitrous oxide and methane in boreal forest.

PubMed

Machacova, Katerina; Bäck, Jaana; Vanhatalo, Anni; Halmeenmäki, Elisa; Kolari, Pasi; Mammarella, Ivan; Pumpanen, Jukka; Acosta, Manuel; Urban, Otmar; Pihlatie, Mari

2016-03-21

Boreal forests comprise 73% of the world's coniferous forests. Based on forest floor measurements, they have been considered a significant natural sink of methane (CH4) and a natural source of nitrous oxide (N2O), both of which are important greenhouse gases. However, the role of trees, especially conifers, in ecosystem N2O and CH4 exchange is only poorly understood. We show for the first time that mature Scots pine (Pinus sylvestris L.) trees consistently emit N2O and CH4 from both stems and shoots. The shoot fluxes of N2O and CH4 exceeded the stem flux rates by 16 and 41 times, respectively. Moreover, higher stem N2O and CH4 fluxes were observed from wet than from dry areas of the forest. The N2O release from boreal pine forests may thus be underestimated and the uptake of CH4 may be overestimated when ecosystem flux calculations are based solely on forest floor measurements. The contribution of pine trees to the N2O and CH4 exchange of the boreal pine forest seems to increase considerably under high soil water content, thus highlighting the urgent need to include tree-emissions in greenhouse gas emission inventories.

Roosevelt elk selection of temperate rain forest seral stages in western Washington

USGS Publications Warehouse

Schroer, Greg L.; Jenkins, Kurt J.; Moorhead, Bruce B.

1993-01-01

We studied habitat selection by Roosevelt elk (Cervus elaphus roosevelti) in a temperate rain forest in the lower Queets River Valley of the western Olympic Peninsula, Washington from June 1986-July 1987. Elk annual home ranges included predominantly unlogged forests protected within Olympic National Park and logged, regenerating forests adjacent to the park. Radio-collared elk selected valley floors during all seasons except winter, when elk frequently used an adjoining plateau 60 m above the floodplain. In winder, radio-collared elk selected 6-15 year-old clearcuts, which were available on the plateau. Elk selected mature deciduous forests of the valley floor during spring, summer, and autumn, and generally they selected old-age Sitka spruce forests during autumn and winter. Young clearcuts (1-5 years old) and even-aged, regenerating stands (16-150 years old) generally were avoided during all seasons. Management practices that retain preferred habitat of elk, such as deciduous forests, 6-15 yr-old coniferous stands, and old-age coniferous bottomland forests will benefit elk, particularly on elk ranges managed for short-rotation, even-aged stands. Silvicultural alternatives to typical even-aged stand management, such as uneven-aged management and commercial thinning, should also be considered for improving and maintaining interspersion of forage and cover.

Incorporating microbial dormancy dynamics into soil decomposition models to improve quantification of soil carbon dynamics of northern temperate forests

NASA Astrophysics Data System (ADS)

He, Yujie; Yang, Jinyan; Zhuang, Qianlai; Harden, Jennifer W.; McGuire, Anthony D.; Liu, Yaling; Wang, Gangsheng; Gu, Lianhong

2015-12-01

Soil carbon dynamics of terrestrial ecosystems play a significant role in the global carbon cycle. Microbial-based decomposition models have seen much growth recently for quantifying this role, yet dormancy as a common strategy used by microorganisms has not usually been represented and tested in these models against field observations. Here we developed an explicit microbial-enzyme decomposition model and examined model performance with and without representation of microbial dormancy at six temperate forest sites of different forest types. We then extrapolated the model to global temperate forest ecosystems to investigate biogeochemical controls on soil heterotrophic respiration and microbial dormancy dynamics at different temporal-spatial scales. The dormancy model consistently produced better match with field-observed heterotrophic soil CO2 efflux (RH) than the no dormancy model. Our regional modeling results further indicated that models with dormancy were able to produce more realistic magnitude of microbial biomass (<2% of soil organic carbon) and soil RH (7.5 ± 2.4 Pg C yr-1). Spatial correlation analysis showed that soil organic carbon content was the dominating factor (correlation coefficient = 0.4-0.6) in the simulated spatial pattern of soil RH with both models. In contrast to strong temporal and local controls of soil temperature and moisture on microbial dormancy, our modeling results showed that soil carbon-to-nitrogen ratio (C:N) was a major regulating factor at regional scales (correlation coefficient = -0.43 to -0.58), indicating scale-dependent biogeochemical controls on microbial dynamics. Our findings suggest that incorporating microbial dormancy could improve the realism of microbial-based decomposition models and enhance the integration of soil experiments and mechanistically based modeling.

Incorporating microbial dormancy dynamics into soil decomposition models to improve quantification of soil carbon dynamics of northern temperate forests

USGS Publications Warehouse

He, Yujie; Yang, Jinyan; Zhuang, Qianlai; Harden, Jennifer W.; McGuire, A. David; Liu, Yaling; Wang, Gangsheng; Gu, Lianhong

2015-01-01

Soil carbon dynamics of terrestrial ecosystems play a significant role in the global carbon cycle. Microbial-based decomposition models have seen much growth recently for quantifying this role, yet dormancy as a common strategy used by microorganisms has not usually been represented and tested in these models against field observations. Here we developed an explicit microbial-enzyme decomposition model and examined model performance with and without representation of microbial dormancy at six temperate forest sites of different forest types. We then extrapolated the model to global temperate forest ecosystems to investigate biogeochemical controls on soil heterotrophic respiration and microbial dormancy dynamics at different temporal-spatial scales. The dormancy model consistently produced better match with field-observed heterotrophic soil CO2 efflux (RH) than the no dormancy model. Our regional modeling results further indicated that models with dormancy were able to produce more realistic magnitude of microbial biomass (<2% of soil organic carbon) and soil RH (7.5 ± 2.4 Pg C yr−1). Spatial correlation analysis showed that soil organic carbon content was the dominating factor (correlation coefficient = 0.4–0.6) in the simulated spatial pattern of soil RHwith both models. In contrast to strong temporal and local controls of soil temperature and moisture on microbial dormancy, our modeling results showed that soil carbon-to-nitrogen ratio (C:N) was a major regulating factor at regional scales (correlation coefficient = −0.43 to −0.58), indicating scale-dependent biogeochemical controls on microbial dynamics. Our findings suggest that incorporating microbial dormancy could improve the realism of microbial-based decomposition models and enhance the integration of soil experiments and mechanistically based modeling.

Quality control troubleshooting tools for the mill floor

Treesearch

John Dramm

2000-01-01

Statistical Process Control (SPC) provides effective tools for improving process quality in the forest products industry resulting in reduced costs and improved productivity. Implementing SPC helps identify and locate problems that occur in wood products manufacturing. SPC tools achieve their real value when applied on the mill floor for monitoring and troubleshooting...

Short-term precipitation exclusion alters microbial responses to soil moisture in a wet tropical forest.

PubMed

Waring, Bonnie G; Hawkes, Christine V

2015-05-01

Many wet tropical forests, which contain a quarter of global terrestrial biomass carbon stocks, will experience changes in precipitation regime over the next century. Soil microbial responses to altered rainfall are likely to be an important feedback on ecosystem carbon cycling, but the ecological mechanisms underpinning these responses are poorly understood. We examined how reduced rainfall affected soil microbial abundance, activity, and community composition using a 6-month precipitation exclusion experiment at La Selva Biological Station, Costa Rica. Thereafter, we addressed the persistent effects of field moisture treatments by exposing soils to a controlled soil moisture gradient in the lab for 4 weeks. In the field, compositional and functional responses to reduced rainfall were dependent on initial conditions, consistent with a large degree of spatial heterogeneity in tropical forests. However, the precipitation manipulation significantly altered microbial functional responses to soil moisture. Communities with prior drought exposure exhibited higher respiration rates per unit microbial biomass under all conditions and respired significantly more CO2 than control soils at low soil moisture. These functional patterns suggest that changes in microbial physiology may drive positive feedbacks to rising atmospheric CO2 concentrations if wet tropical forests experience longer or more intense dry seasons in the future.

Production, Stocks and Characteristics of Wildfire Charcoal in Canadian Boreal Forests; a Preliminary Synthesis

NASA Astrophysics Data System (ADS)

Preston, C. M.; Simard, M.

2016-12-01

Crowning wildfires are a major driver of carbon stocks and ecosystem development in Canadian boreal forests, but there is insufficient information to incorporate pyrogenic carbon (PyC) into models and management strategies. Data comparison is challenging because of varied experimental design, and studies are often limited to forest floor; nonetheless we have attempted a synthesis limited to visually determined PyC, hereafter designated "charcoal". Sources include our study of amounts, depth distribution (forest floor plus variable amounts of upper mineral soil) and chemical properties of charcoal (>2 mm) from a fire chronosequence in the Abitibi region of Quebec (51 jack pine (Pinus banksiana) and black spruce (Picea mariana) sites, 24 to 2355 years since fire). Complete charcoal production of 7900 kg/ha (forest floor, down wood, standing stems) was determined from an experimental crownfire in jack pine near Fort Providence (NWT) in 2012. Published data were assembled mainly from boreal conifer studies, but using more disparate sources for production, plus laboratory charring studies. Typical findings include high spatial variability, with depth distributions often showing a maximum around the organic-mineral interface. Stocks varied widely (up to ca. 5500 kg/ha), with little initial discernable trend with time, but were much lower in the few older sites (>700y). Total C and N were widely scattered for younger samples, but older samples were mainly 500-600 g C/kg with C/N values around 100. Similarly, carbon-13 NMR spectra show wider variation in young samples, with the oldest samples being highly aromatic. These initial variations are consistent with field reports of highly variable temperatures and duration of charring and many laboratory studies. As a starting point, it may be possibly suggested that a boreal crowning wildfire might produce some 5000-10000 kg/ha of charred material of 550-650 g C/kg, with half to two-thirds on forest floor and down wood and most of the rest on standing stems. Our synthesis mainly highlights future research needs, including more measurements on stems and down wood and chemical analysis of the black carbon component of charcoal.

5. Photo copy of photograph, (original in Forest Service Office, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. Photo copy of photograph, (original in Forest Service Office, Elkins, WV, photo #298181), D. A. Oliver, 1934. LOWER FLOOR, LOOKING WEST, SEED EXTRACTOR. - Parsons Nursery, Seed Extractor Building, South side of U.S. Route 219, Parsons, Tucker County, WV

Vertical Structure of Phyllosphere Fungal Communities in a Tropical Forest in Thailand Uncovered by High-Throughput Sequencing.

PubMed

Izuno, Ayako; Kanzaki, Mamoru; Artchawakom, Taksin; Wachrinrat, Chongrak; Isagi, Yuji

2016-01-01

Phyllosphere fungi harbor a tremendous species diversity and play important ecological roles. However, little is known about their distribution patterns within forest ecosystems. We examined how species diversity and community composition of phyllosphere fungi change along a vertical structure in a tropical forest in Thailand. Fungal communities in 144 leaf samples from 19 vertical layers (1.28-34.4 m above ground) of 73 plant individuals (27 species) were investigated by metabarcoding analysis using Ion Torrent sequencing. In total, 1,524 fungal operational taxonomic units (OTUs) were detected among 890,710 reads obtained from the 144 leaf samples. Taxonomically diverse fungi belonging to as many as 24 orders of Ascomycota and 21 orders of Basidiomycota were detected, most of which inhabited limited parts of the lowest layers closest to the forest floor. Species diversity of phyllosphere fungi was the highest in the lowest layers closest to the forest floor, decreased with increasing height, and lowest in the canopy; 742 and 55 fungal OTUs were detected at the lowest and highest layer, respectively. On the layers close to the forest floor, phyllosphere fungal communities were mainly composed of low frequency OTUs and largely differentiated among plant individuals. Conversely, in the canopy, fungal communities consisted of similar OTUs across plant individuals, and as many as 86.1%-92.7% of the OTUs found in the canopy (≥22 m above ground) were also distributed in the lower layers. Overall, our study showed the variability of phyllosphere fungal communities along the vertical gradient of plant vegetation and environmental conditions, suggesting the significance of biotic and abiotic variation for the species diversity of phyllosphere fungi.

Tree fern trunks facilitate seedling regeneration in a productive lowland temperate rain forest.

PubMed

Gaxiola, Aurora; Burrows, Larry E; Coomes, David A

2008-03-01

Seedling regeneration on forest floors is often impaired by competition with established plants. In some lowland temperate rain forests, tree fern trunks provide safe sites on which tree species establish, and grow large enough to take root in the ground and persist. Here we explore the competitive and facilitative effects of two tree fern species, Cyathea smithii and Dicksonia squarrosa, on the epiphytic regeneration of tree species in nutrient-rich alluvial forests in New Zealand. The difficulties that seedlings have in establishing on vertical tree fern trunks were indicated by the following observations. First, seedling abundance was greatest on the oldest sections of tree fern trunks, near the base, suggesting that trunks gradually recruited more and more seedlings over time, but many sections of trunk were devoid of seedlings, indicating the difficulty of establishment on a vertical surface. Second, most seedlings were from small-seeded species, presumably because smaller seeds can easily lodge on tree fern trunks. Deer browsing damage was observed on 73% of epiphytic seedlings growing within 2 m of the ground, whereas few seedlings above that height were browsed. This suggests that tree ferns provide refugia from introduced deer, and may slow the decline in population size of deer-preferred species. We reasoned that tree ferns would compete with epiphytic seedlings for light, because below the tree fern canopy photosynthetically active radiation (PAR) was about 1% of above-canopy PAR. Frond removal almost tripled %PAR on the forest floor, leading to a significant increase in the height growth rate (HGR) of seedlings planted on the forest floor, but having no effects on the HGRs of epiphytic seedlings. Our study shows evidence of direct facilitative interactions by tree ferns during seedling establishment in plant communities associated with nutrient-rich soils.

Earthworm effects on the incorporation of litter C and N into soil organic matter in a sugar maple forest.

PubMed

Fahey, Timothy J; Yavitt, Joseph B; Sherman, Ruth E; Maerz, John C; Groffman, Peter M; Fisk, Melany C; Bohlen, Patrick J

2013-07-01

To examine the mechanisms of earthworm effects on forest soil C and N, we double-labeled leaf litter with 13C and 15N, applied it to sugar maple forest plots with and without earthworms, and traced isotopes into soil pools. The experimental design included forest plots with different earthworm community composition (dominated by Lumbricus terrestris or L. rubellus). Soil carbon pools were 37% lower in earthworm-invaded plots largely because of the elimination of the forest floor horizons, and mineral soil C:N was lower in earthworm plots despite the mixing of high C:N organic matter into soil by earthworms. Litter disappearance over the first winter-spring was highest in the L. terrestris (T) plots, but during the warm season, rapid loss of litter was observed in both L. rubellus (R) and T plots. After two years, 22.0% +/- 5.4% of 13C released from litter was recovered in soil with no significant differences among plots. Total recovery of added 13C (decaying litter plus soil) was much higher in no-worm (NW) plots (61-68%) than in R and T plots (20-29%) as much of the litter remained in the former whereas it had disappeared in the latter. Much higher percentage recovery of 15N than 13C was observed, with significantly lower values for T than R and NW plots. Higher overwinter earthworm activity in T plots contributed to lower soil N recovery. In earthworm-invaded plots isotope enrichment was highest in macroaggregates and microaggregates whereas in NW plots silt plus clay fractions were most enriched. The net effect of litter mixing and priming of recalcitrant soil organic matter (SOM), stabilization of SOM in soil aggregates, and alteration of the soil microbial community by earthworm activity results in loss of SOM and lowering of the C:N ratio. We suggest that earthworm stoichiometry plays a fundamental role in regulating C and N dynamics of forest SOM.

Properties of dissolved and total organic matter in throughfall, stemflow and forest floor leachate of Central European forests

NASA Astrophysics Data System (ADS)

Bischoff, S.; Schwarz, M. T.; Siemens, J.; Thieme, L.; Wilcke, W.; Michalzik, B.

2014-10-01

For the first time, we investigated the composition of dissolved organic matter (DOM) compared to total OM (TOM, consisting of DOM and particulate OM, POM) in throughfall, stemflow and forest floor leachate of beech and spruce forests using solid state 13C nuclear magnetic resonance spectroscopy. We hypothesized that the composition and properties of OM in forest ecosystem water samples differed between DOM and TOM and between the two tree species. Under beech, a contribution of phyllosphere-derived fresh POM was echoed in structural differences. Compared with DOM, TOM exhibited higher relative intensities for the alkyl C region, representing aliphatic C from less decomposed organic material, and lower relative intensities for lignin-derived and aromatic C of the aryl C region, resulting in lower aromaticity indices and reduced humification intensities. Since differences in the structural composition of DOM and TOM were less pronounced under spruce than under beech, we suspect a~tree species-related effect on the origin of OM composition and resulting properties (e.g. recalcitrance, allelopathic potential).

Abundance and activity of soil microorganisms in Cedrus atlantica forests are more related to land use than to altitude or latitude

NASA Astrophysics Data System (ADS)

Ramírez Rojas, Irene; Perez Fernandez, María; Moreno Gallardo, Laura; Lechuga Ordoñez, Victor; Linares, Juan Carlos

2016-04-01

Several environmental traits might change the abundance and the function of soil microorganisms in forest soils by plant-mediated reactions. Few studies have related the landscape-scale forest structural diversity with the micro-scale distribution of microorganism and their activities. High mountain environments harbor ecosystems that are very sensitive to global change and hence highly vulnerable, as those of Atlantic cedar. Altitudinal gradients in mountains are orrelated with changes in vegetation. We propose that altitudinal gradients drive shifts in microbial communities and are correlated with land uses. Thus, the latitudinal and longitudinal pattern of abundance and activity of soil micro-organisms was studied in an intercontinental comparison. We investigate soil extractable organic carbon (EOC) and nitrogen and carbon, microbial biomass and microbial metabolic activities at eight different sites along the latitudinal range of Cedrus atlantica, covering different altitudes and soils characteristics both in Southern Spain and Northern Morocco. Analyses of the abundances of total bacteria, (16S rRNA gene), was conducted using the Ilumina metagenomics technique. Results show that the stands at the highest altitudes had distinct microbial and biochemical characteristics compared with other areas. Overall, microbial activity, as measured by soil respiration, is higher in forests subjected to lower human pressure than in stands highly degraded, probably reflecting the quality of litter input that results of the influence of local assemblage of different tree, shrub and annual species, though changes in the soil N and C contents. Indeed, total soil C and N contents explained the microbial properties at every scale. Our results suggest that in contrast to the observed pronounced altitudinal changes, the kind of human-mediate land management has a stronger role in defining changes in microbial composition and activities in the investigated forest systems.

Projections of forest contributions to global carbon cycles

Treesearch

Michael E. Goerndt; Stephen R. Shifley; Patrick D. Miles; Dave Wear; Francisco X. Aguilar

2016-01-01

Forests cover 42 percent of the Northern United States, and collectively they store 13 billion tons of carbon in live trees (29 percent), roots (6 percent), forest floor (9 percent), dead trees (6 percent), and soils (50 percent). About half the biomass of a live tree (dry weight basis) is sequestered carbon (Woodall et al. 2011) - not the largest but the most dynamic...

Stereo photo series for quantifying natural fuels. Volume XII: Post-hurricane fuels in forests of the Southeast United States.

Treesearch

Robert E. Vihnanek; Cameron S. Balog; Clinton S. Wright; Roger D. Ottmar; Jeffrey W. Kelly

2009-01-01

Two series of single and stereo photographs display a range of natural conditions and fuel loadings in post-hurricane forests in the southeastern United States. Each group of photos includes inventory information summarizing vegetation composition, structure and loading, woody material loading and density by size class, forest floor loading, and various site...

Soil-seed bank survival in forests of the southern United States

Treesearch

James S. Meadows; Frank T. Bonner; James D. Haywood

2006-01-01

We evaluated the longevity of seeds of 12 common woody species buried in fresh condition in the forest floor at three forest locations in Mississippi and Louisiana. Seed samples of each species were retrieved annually for 5 years from each location. Germination and tetrazolium chloride staining tests were conducted on the samples to determine germinative capacity. When...

Dynamics of calcium concentration in stemwood of red spruce and Siberian fir

Treesearch

Kevin T. Smith; Walter C. Shortle; Rakesh Minocha; Vladislav A. Alexeyev

1996-01-01

The atmospheric deposition of strong acid anions such as sulfate and nitrate shifts the ion exchange equilibrium in the rooting zone of sensitive forests. Red spruce and other northern coniferous forests are especially sensitive to deposition due to the shallow rooting of trees in a mor-type forest floor. Initially, the deposition of strong acid ions mobilizes...

Harvesting forest residues for bioenergy influences amphibian and herbaceous plant community assemblages in northern hardwood forests

Treesearch

Deahn M. Donner; Christine A. Ribic; Matthew St. Pierre; Daniel Eklund

2011-01-01

The most readily available source of woody biomass is through whole-tree harvesting that removes what has been traditionally left as slash [i.e., fine woody debris (FWD)]. While FWD has the potential to be used as energy feedstock, a critical element of managing for biodiversity is maintaining woody debris on the forest floor.

The Contribution of Microarthropods to Aboveground Food Webs: A Review and Model of Belowground Transfer in a Coniferous Forest

Treesearch

John M. Johnston

1999-01-01

Although below ground food webs have received much attention, studies concerning microarthropods in nondetrital food webs are scarce. because adult oribatid mites often number between 250.000-500,000/ m2 in coniferous forests, microarthropods are a potential food resource for macroarthropod and vertebrate predators of the forest floor. Although...

Land use change effects on forest carbon cycling throughout the southern United States

Treesearch

Peter B. Woodbury; Linda S. Heath; James E. Smith

2006-01-01

We modeled the effects of afforestation and deforestation on carbon cycling in forest floor and soil from 1900 to 2050 throughout 13 states in the southern United States. The model uses historical data on gross (two-way) transitions between forest, pasture, plowed agriculture, and urban lands along with equations describing changes in carbon over many decades for each...

Life on the edge: carbon fluxes from wetland to ocean along Alaska's coastal temperate rain forest

Treesearch

Rhonda Mazza; Richard Edwards; David D' Amore

2010-01-01

Acre for acre, streams of the coastal temperate rain forest along the Gulf of Alaska export 36 times as much dissolved organic carbon as the world average. Rain and snow are the great connectors, tightly linking aquatic and terrestrial systems of this region. The freshwater that flushes over and through the forest floor leaches carbon...

Quantifying the coarse-root biomass of intensively managed loblolly pine plantations

Treesearch

Ashley T. Miller; H. Lee Allen; Chris A. Maier

2006-01-01

Most of the carbon accumulation during a forest rotation is in plant biomass and the forest floor. Most of the belowground biomass in older loblolly pine (Pinus taeda L.) forests is in coarse roots, and coarse roots persist longer after harvest than aboveground biomass and fine roots. The main objective was to assess the carbon accumulation in coarse...

Quantifying the coarse-root biomass of intensively managed loblolly pine plantations

Treesearch

Ashley T. Miller; H. Lee Allen; Chris A. Maier

2006-01-01

Most of the carbon accumulation during a forest rotation is in plant biomass and the forest floor. Most of the belowground biomass in older loblolly pine (Pinus taeda L.) forests is in coarse roots, and coarse roots ersist longer after harvest than aboveground biomass and fine oots. The main objective was to assess the carbon accumulation in coarse...

Thinning effects on spotted owl prey and other forest-dwelling small mammals

Treesearch

Todd M. Willson; Eric D. Forsman

2013-01-01

Th inning has been promoted as a method for accelerating the development of late-seral habitat and improving the overall health and function of young forests in the Pacifi c Northwest. Population studies have shown early and positive responses to thinning by some small forest-floor mammals (primarily mice, terrestrial voles, and shrews). However, thinning reduces the...

Forest nutrient and carbon pools at Walker Branch watershed: changes during a 21-year period

Treesearch

Carl C. Trettin; D.W. Johnson; D.E. Todd

1999-01-01

A 21-yr perspective on changes in nutrient and C pools on undisturbed upland forest sites is provided. Plots originally representing four cover types have been sampled three times. On each plot, forest biomass, forest floor, and soil, to a depth of 60 cm, were measured, sampled, and analyzed for Ca, Mg, C, N, and P. Exchangeable soil Ca and Mg have declined in most...

4. Photo copy of photograph, (original in Forest Service Office, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. Photo copy of photograph, (original in Forest Service Office, Elkins, WV, photo #298180, 'seed extracting equipment'), D. A. Oliver, 1934. LOWER FLOOR, LOOKING WEST, SEED EXTRACTOR. - Parsons Nursery, Seed Extractor Building, South side of U.S. Route 219, Parsons, Tucker County, WV

Vertical variability and effect of stability on turbulence characteristics down to the floor of a pine forest

NASA Astrophysics Data System (ADS)

Launiainen, Samuli; Vesala, Timo; Mölder, Meelis; Mammarella, Ivan; Smolander, Sampo; Rannik, Üllar; Kolari, Pasi; Hari, Pertti; Lindroth, Anders; Katul, Gabriel G.

2007-11-01

Among the fundamental problems in canopy turbulence, particularly near the forest floor, remain the local diabatic effects and linkages between turbulent length scales and the canopy morphology. To progress on these problems, mean and higher order turbulence statistics are collected in a uniform pine forest across a wide range of atmospheric stability conditions using five 3-D anemometers in the subcanopy. The main novelties from this experiment are: (1) the agreement between second-order closure model results and measurements suggest that diabatic states in the layer above the canopy explain much of the modulations of the key velocity statistics inside the canopy except in the immediate vicinity of the trunk space and for very stable conditions. (2) The dimensionless turbulent kinetic energy in the trunk space is large due to a large longitudinal velocity variance but it is inactive and contributes little to momentum fluxes. (3) Near the floor layer, a logarithmic mean velocity profile is formed and vertical eddies are strongly suppressed modifying all power spectra. (4) A spectral peak in the vertical velocity near the ground commensurate with the trunk diameter emerged at a moderate element Reynolds number consistent with Strouhal instabilities describing wake production.

Type of litter determines the formation and properties of charred material during wildfires

NASA Astrophysics Data System (ADS)

Chavez, Bruno; Fonturbel, M. Teresa; Salgado, Josefa; García-Oliva, Felipe; Vega, Jose A.; Merino, Agustin

2014-05-01

Wildfire is one of the most important disturbances all over the World, affecting both the amount and composition of forest floor and mineral soils. In comparison with unburnt areas, wildfire-affected forest floor usually shows lower contents of labile C compounds and higher concentrations of recalcitrant aromatic forms. These changes in composition can have important impact on biogeochemical cycles and therefore ecosystem functions. Although burning of different types of litter can lead to different amount and types of pyrogenic compounds, this aspect has not been evaluated yet. The effect of wildfire on SOM composition and stability were evaluated in five major types of non-wood litter in Mediterranean ecosystems: Pinus nigra, E. arborea, P. pinaster, U. europaeus and Eucalyptus globulus. In each of these ecosystems, forest floor samples from different soil burn severities were sampled. Soil burnt severities were based on visual signs of changes in forest floor and deposition of ash. Pyrogenic carbon quality were analysed using elementary analysis, solid-state 13 C nuclear magnetic resonance spectroscopy, Reflectance Infrared Fourier Transform (FTIR) and thermal analysis (simultaneous DSC-TG). The study showed that the different types of litter influenced the formation and characteristics of charred material. They differed in the temperature at which they start to be formed, the amounts of charred compounds and in their chemical composition. The resulting charred materials from the different litter, showed an important variability in the degree of carbonitation/aromatization. Unlike the biochar obtained through pyrolysis of woody sources, which contains exclusively aromatic structures, in the charred material produced in some litter, lignin, cellulose and even cellulose persist even in the high soil burnt severity. Coinciding with increases in aromatic contents, important decreases in atomic H/C and O/C ratios were recorded. However, the values found in some litters, were higher than 0.5, suggesting that low degree of carbonization/aromatization. Although burning also led to compounds of higher thermal recalcitrance (increases in T50 values), values recorded in some litters were lower than those measured in highly polycondensed aromatic compounds. The differences found among the different forest floor cannot be only attributable to the initial SOM composition of the litter. Other aspects, such as the different thermal sensitivity, flammability and different conditions during wildfire (temperatures, combustion duration, oxygen concentrations) could also have contributed.

Incorporating microbial dormancy dynamics into soil decomposition models to improve quantification of soil carbon dynamics of northern temperate forests

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

He, Yujie; Yang, Jinyan; Zhuang, Qianlai

Soil carbon dynamics of terrestrial ecosystems play a significant role in the global carbon cycle. Microbial-based decomposition models have seen much growth recently for quantifying this role, yet dormancy as a common strategy used by microorganisms has not usually been represented and tested in these models against field observations. Here in this study we developed an explicit microbial-enzyme decomposition model and examined model performance with and without representation of microbial dormancy at six temperate forest sites of different forest types. We then extrapolated the model to global temperate forest ecosystems to investigate biogeochemical controls on soil heterotrophic respiration and microbialmore » dormancy dynamics at different temporal-spatial scales. The dormancy model consistently produced better match with field-observed heterotrophic soil CO 2 efflux (R H) than the no dormancy model. Our regional modeling results further indicated that models with dormancy were able to produce more realistic magnitude of microbial biomass (<2% of soil organic carbon) and soil R H (7.5 ± 2.4 PgCyr -1). Spatial correlation analysis showed that soil organic carbon content was the dominating factor (correlation coefficient = 0.4-0.6) in the simulated spatial pattern of soil R H with both models. In contrast to strong temporal and local controls of soil temperature and moisture on microbial dormancy, our modeling results showed that soil carbon-to-nitrogen ratio (C:N) was a major regulating factor at regional scales (correlation coefficient = -0.43 to -0.58), indicating scale-dependent biogeochemical controls on microbial dynamics. Our findings suggest that incorporating microbial dormancy could improve the realism of microbial-based decomposition models and enhance the integration of soil experiments and mechanistically based modeling.« less

Microbial Indicators of Soil Quality under Different Land Use Systems in Subtropical Soils

NASA Astrophysics Data System (ADS)

Maharjan, M.

2016-12-01

Land-use change from native forest to intensive agricultural systems can negatively impact numerous soil parameters. Understanding the effects of forest ecosystem transformations on markers of long-term soil health is particularly important in rapidly developing regions such as Nepal, where unprecedented levels of agriculturally-driven deforestation have occurred in recent decades. However, the effects of widespread land use changes on soil quality in this region have yet to be properly characterized. Microbial indicators (soil microbial biomass, metabolic quotient and enzymes activities) are particularly suited to assessing the consequences of such ecosystem disturbances, as microbial communities are especially sensitive to environmental change. Thus, the aim of this study was to assess the effect of land use system; i.e. forest, organic and conventional farming, on soil quality in Chitwan, Nepal using markers of microbial community size and activity. Total organic C and N contents were higher in organic farming compared with conventional farming and forest, suggesting higher nutrient retention and soil preservation with organic farming practices compared to conventional. These differences in soil composition were reflected in the health of the soil microbial communities: Organic farm soil exhibited higher microbial biomass C, elevated β-glucosidase and chitinase activities, and a lower metabolic quotient relative to other soils, indicating a larger, more active, and less stressed microbial community, respectively. These results collectively demonstrate that application of organic fertilizers and organic residues positively influence nutrient availability, with subsequent improvements in soil quality and productivity. Furthermore, the sensitivity of microbial indicators to different management practices demonstrated in this study supports their use as effective markers of ecosystem disturbance in subtropical soils.

Changes in soil microbial community structure influenced by agricultural management practices in a mediterranean agro-ecosystem.

PubMed

García-Orenes, Fuensanta; Morugán-Coronado, Alicia; Zornoza, Raul; Cerdà, Artemi; Scow, Kate

2013-01-01

Agricultural practices have proven to be unsuitable in many cases, causing considerable reductions in soil quality. Land management practices can provide solutions to this problem and contribute to get a sustainable agriculture model. The main objective of this work was to assess the effect of different agricultural management practices on soil microbial community structure (evaluated as abundance of phospholipid fatty acids, PLFA). Five different treatments were selected, based on the most common practices used by farmers in the study area (eastern Spain): residual herbicides, tillage, tillage with oats and oats straw mulching; these agricultural practices were evaluated against an abandoned land after farming and an adjacent long term wild forest coverage. The results showed a substantial level of differentiation in the microbial community structure, in terms of management practices, which was highly associated with soil organic matter content. Addition of oats straw led to a microbial community structure closer to wild forest coverage soil, associated with increases in organic carbon, microbial biomass and fungal abundances. The microbial community composition of the abandoned agricultural soil was characterised by increases in both fungal abundances and the metabolic quotient (soil respiration per unit of microbial biomass), suggesting an increase in the stability of organic carbon. The ratio of bacteria:fungi was higher in wild forest coverage and land abandoned systems, as well as in the soil treated with oat straw. The most intensively managed soils showed higher abundances of bacteria and actinobacteria. Thus, the application of organic matter, such as oats straw, appears to be a sustainable management practice that enhances organic carbon, microbial biomass and activity and fungal abundances, thereby changing the microbial community structure to one more similar to those observed in soils under wild forest coverage.

[Changes in soil organic carbon and soil microbial functional diversity of Carya cathayensis plantations under intensive managements].

PubMed

Wu, Jia-Sen; Qian, Jin-Fang; Tong, Zhi-Peng; Huang, Jian-Qin; Zhao, Ke-Li

2014-09-01

The change characteristics of soil organic carbon and microbial function diversity in Chinese hickory Carya cathayensis stands with different intensive-management durations (5, 10, 15 and 20 years) were studied. The results showed that soil total organic carbon (TOC), microbial biomass carbon (MBC), water-soluble organic carbon (WSOC) decreased significantly, while the stability of soil C pool increased significantly after the conversion from evergreen and deciduous broadleaf forest to intensively-managed forest (IMF). TOC, MBC and WSOC in the hickory forest soil decreased by 28.4%, 34.1% and 53.3% with 5-year intensive management, and by 38.6%, 48.9% and 64.1% with 20-year intensive management, respectively. The proportions of carboxyl C, phenolic C and aromatic C in the hickory forest soil all increased significantly, and the aromaticity of soil organic C increased by 23.0%. Soil microbial functional diversity decreased greatly af- ter intensive management of Chinese hickory forest. Significant differences in average well color development (AWCD) were found between the 0- and 5-year treatments and the 10-, 15- and 20- year treatments. The microbial diversity indexes (H) and evenness indexes (E) in the 0- and 5-year treatments were much greater than in the 10- and 20-year treatments. Correlation analysis showed that there were significant correlations among soil TOC, WSOC, MBC, AWCD, H and E.

Nitrogen dynamics across silvicultural canopy gaps in young forests of western Oregon

USGS Publications Warehouse

Thiel, A.L.; Perakis, S.S.

2009-01-01

Silvicultural canopy gaps are emerging as an alternative management tool to accelerate development of complex forest structure in young, even-aged forests of the Pacific Northwest. The effect of gap creation on available nitrogen (N) is of concern to managers because N is often a limiting nutrient in Pacific Northwest forests. We investigated patterns of N availability in the forest floor and upper mineral soil (0-10 cm) across 6-8-year-old silvicultural canopy gaps in three 50-70-year-old Douglas-fir forests spanning a wide range of soil N capital in the Coast Range and Cascade Mountains of western Oregon. We used extractable ammonium (NH4+) and nitrate (NO3-) pools, net N mineralization and nitrification rates, and NH4+ and NO3- ion exchange resin (IER) concentrations to quantify N availability along north-south transects run through the centers of 0.4 and 0.1 ha gaps. In addition, we measured several factors known to influence N availability, including litterfall, moisture, temperature, and decomposition rates. In general, gap-forest differences in N availability were more pronounced in the mineral soil than in the forest floor. Mineral soil extractable NH4+ and NO3- pools, net N mineralization and nitrification rates, and NH4+ and NO3- IER concentrations were all significantly elevated in gaps relative to adjacent forest, and in several cases exhibited significantly greater spatial variability in gaps than forest. Nitrogen availability along the edges of gaps more often resembled levels in the adjacent forest than in gap centers. For the majority of response variables, there were no significant differences between northern and southern transect positions, nor between 0.4 and 0.1 ha gaps. Forest floor and mineral soil gravimetric percent moisture and temperature showed few differences along transects, while litterfall carbon (C) inputs and litterfall C:N ratios in gaps were significantly lower than in the adjacent forest. Reciprocal transfer incubations of mineral soil samples between gap and forest positions revealed that soil originating from gaps had greater net nitrification rates than forest samples, regardless of incubation environment. Overall, our results suggest that increased N availability in 6-8-year-old silvicultural gaps in young western Oregon forests may be due more to the quality and quantity of litterfall inputs resulting from early-seral species colonizing gaps than by changes in temperature and moisture conditions caused by gap creation.

Direct and indirect influence of parental bedrock on streambed microbial community structure in forested streams.

PubMed

Mosher, Jennifer J; Findlay, Robert H

2011-11-01

A correlative study was performed to determine if variation in streambed microbial community structure in low-order forested streams can be directly or indirectly linked to the chemical nature of the parental bedrock of the environments through which the streams flow. Total microbial and photosynthetic biomass (phospholipid phosphate [PLP] and chlorophyll a), community structure (phospholipid fatty acid analysis), and physical and chemical parameters were measured in six streams, three located in sandstone and three in limestone regions of the Bankhead National Forest in northern Alabama. Although stream water flowing through the two different bedrock types differed significantly in chemical composition, there were no significant differences in total microbial and photosynthetic biomass in the sediments. In contrast, sedimentary microbial community structure differed between the bedrock types and was significantly correlated with stream water ion concentrations. A pattern of seasonal variation in microbial community structure was also observed. Further statistical analysis indicated dissolved organic matter (DOM) quality, which was previously shown to be influenced by geological variation, correlated with variation in bacterial community structure. These results indicate that the geology of underlying bedrock influences benthic microbial communities directly via changes in water chemistry and also indirectly via stream water DOM quality.

First direct landscape-scale measurement of tropical rain forest Leaf Area Index, a key driver of global primary productivity

Treesearch

David B. Clark; Paulo C. Olivas; Steven F. Oberbauer; Deborah A. Clark; Michael G. Ryan

2008-01-01

Leaf Area Index (leaf area per unit ground area, LAI) is a key driver of forest productivity but has never previously been measured directly at the landscape scale in tropical rain forest (TRF). We used a modular tower and stratified random sampling to harvest all foliage from forest floor to canopy top in 55 vertical transects (4.6 m2) across 500 ha of old growth in...

Mercury in litterfall and upper soil horizons in forested ecosystems in Vermont, USA.

PubMed

Juillerat, Juliette I; Ross, Donald S; Bank, Michael S

2012-08-01

Mercury (Hg) is an atmospheric pollutant that, in forest ecosystems, accumulates in foliage and upper soil horizons. The authors measured soil and litterfall Hg at 15 forest sites (northern hardwood to mixed hardwood/conifer) throughout Vermont, USA, to examine variation among tree species, forest type, and soils. Differences were found among the 12 tree species sampled from at least two sites, with Acer pensylvanicum having significantly greater litterfall total Hg concentration. Senescent leaves had greater Hg concentrations if they originated lower in the canopy or had higher surface:weight ratios. Annual litterfall Hg flux had a wide range, 12.6 to 28.5 µg/m(2) (mean, 17.9 µg/m(2) ), not related to forest type. Soil and Hg pools in the Oi horizon (litter layer) were not related to the measured Hg deposition flux in litterfall or to total modeled Hg deposition. Despite having lower Hg concentrations, upper mineral soil (A horizons) had greater Hg pools than organic soil horizons (forest floor) due to greater bulk density. Significant differences were found in Hg concentration and Hg/C ratio among soil horizons but not among forest types. Overall, our findings highlight the importance of site history and the benefits of collecting litterfall and soils simultaneously. Observed differences in forest floor Hg pools were strongly correlated with carbon pools, which appeared to be a function of historic land-use patterns. Copyright © 2012 SETAC.

Potential effects of forest management on surface albedo

NASA Astrophysics Data System (ADS)

Otto, J.; Bréon, F.-M.; Schelhaas, M.-J.; Pinty, B.; Luyssaert, S.

2012-04-01

Currently 70% of the world's forests are managed and this figure is likely to rise due to population growth and increasing demand for wood based products. Forest management has been put forward by the Kyoto-Protocol as one of the key instruments in mitigating climate change. For temperate and boreal forests, the effects of forest management on the stand-level carbon balance are reasonably well understood, but the biophysical effects, for example through changes in the albedo, remain elusive. Following a modeling approach, we aim to quantify the variability in albedo that can be attributed to forest management through changes in canopy structure and density. The modelling approach chains three separate models: (1) a forest gap model to describe stand dynamics, (2) a Monte-Carlo model to estimate the probability density function of the optical path length of photons through the canopy and (3) a physically-based canopy transfer model to estimate the interaction between photons and leaves. The forest gap model provides, on a monthly time step the position, height, diameter, crown size and leaf area index of individual trees. The Monte-Carlo model computes from this the probability density function of the distance a photon travels through crown volumes to determine the direct light reaching the forest floor. This information is needed by the canopy transfer model to calculate the effective leaf area index - a quantity that allows it to correctly represent a 3D process with a 1D model. Outgoing radiation is calculated as the result of multiple processes involving the scattering due to the canopy layer and the forest floor. Finally, surface albedo is computed as the ratio between incident solar radiation and calculated outgoing radiation. The study used two time series representing thinning from below of a beech and a Scots pine forest. The results show a strong temporal evolution in albedo during stand establishment followed by a relatively stable albedo once the canopy is closed. During this period, albedo is affected for a short time by forest operations. The modelling approach allowed us to estimate the importance of ground vegetation in the stand albedo. Given that ground vegetation depends on the light reaching the forest floor, ground vegetation could act as a natural buffer to dampen changes in albedo, allowing the stand to maintain optimal leaf temperature. Consequently, accounting for only the carbon balance component of forest management ignores albedo impacts and is thus likely to yield biased estimates of the climate benefits of forest ecosystems.

Response of Northwest Douglas-fir stands to urea: correlations with forest soil properties.

Treesearch

C.E. Peterson; P.J. Ryan; S.P. Gessel

1984-01-01

Replicated forest floor and surface soil (0–15 cm) samples were obtained from control plots at 160 field installations to western Washington and Oregon. Six year growth responses of thinned and unthinned Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] in stallations treated with 0, 224, and 448 kg of urea-N ha-1 were correlated with 18 forest...

Factors Affecting Salamander Density and Distribution within Four Forest Types in Southern Appalachian Mountains

Treesearch

Craig A. Harper; David C. Guynn

1999-01-01

We used a terrestrial vacuum to sample known area plots in order to obtain density estimates of salamanders and their primary prey, invertebrates of the forest floor. We sampled leaf litter and measured various vegetative and topographic parameters within four forest types (oak-pine, oak-hickory, mixed mesophytic and northern hardwoods) and three age classes (0-12,13-...

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 (...

Effect of soil compaction and organic matter removal on two earthworm populations and some soil properties in a hardwood forest

Treesearch

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

1999-01-01

Earthworms can alter the physical, chemical, and biological properties of a forest ecosystem. Any physical manipulation to the soil ecosystem may, in turn, affect the activities and ecology of earthworms. The effects of organic matter removal (logs and forest floor) and soil compaction on earthworm activities were measured in a central hardwood region (oakhickory)...

Impacts of harvesting forest residues for bioenergy on herptofauna and herbaceous plant community assemblages in northern hardwood forests

Treesearch

Deahn M. Donner; Christine A. Ribic; Matthew St. Pierre; Dan Eklund

2011-01-01

The most readily available source of woody biomass is through whole-tree harvesting that removes what has been traditionally left as slash [i.e., fine woody debris (FWD)]. While FWD has the potential to be used as energy feedstock, a critical element of managing for biodiversity is maintaining woody debris on the forest floor.

Distribution of Slash and Litter After Wet- and Dry-Site Harvesting of Loblolly Pine Plantations

Treesearch

Mark H. Eisenbies; James A. Burger; Yi-Jun Xu; Steve Patterson

2002-01-01

Displacement of logging slash and forest floor litter in the process of harvesting can interfere with forest nutrient cycling and can modify soil climate in ways that could affect regeneration success and forest productivity. The objective of this study was to assess a visual method for estimating organic matter and slash biomass residues following a typical feller-...

When the douglas-firs were counted: The beginning of the Forest Survey

Treesearch

Ivan Doig

1976-01-01

The wonders which Phil Briegleb remembered from that stint of work - the dark green spill of forest from ridgeline to valley floor, the colonnade of giant boles crowding acre upon acre, the Depression-staving paycheck earned by sizing up this big timber - may have been grand, all right, but no more so than the language which spelled out the project. The Forest Survey...

National Wild Turkey Federation Programs

Treesearch

Rob Keck

2005-01-01

I recently read an article about several women who were preparing to sit 80 ft (25 m) above a forest floor in tree-sitting nets to protest a logging operation in Jefferson National Forest (Appalachia). Tree hugging is nothing new in this country. But did environmental activists know we have more forests now than we did in the 1920s? In 1920, we only had 735 million ac...

Precipitation nutrients in the open and under two forests in Minnesota

Treesearch

Elon S. Verry; D.R. Timmons

1977-01-01

Concentrations of N, P, K, Ca, Mg, and Na were measured in rain and snow in the open, and in throughfall and stemflow under black spruce and aspen forests in north-central Minnesota. Concentrations of total P in rain and black spruce throughfall were inversely related to storm size. Annual precipitation nutrient inputs to the forest floor were calculated for each site...

Ecosystem Function in Appalachian Headwater Streams during an Active Invasion by the Hemlock Woolly Adelgid

Treesearch

Robert M. Northington; Jackson R. Webster; Ernest F. Benfield; Beth M. Cheever; Barbara R. Niederlehner

2013-01-01

Forested ecosystems in the southeastern United States are currently undergoing an invasion by the hemlock woolly adelgid (HWA). Previous studies in this area have shown changes to forest structure, decreases in canopy cover, increases in organic matter, and changes to nutrient cycling on the forest floor and soil. Here, we were interested in how the effects of canopy...

Does the precipitation redistribution of the canopy sense in the moisture pattern of the forest litter?

NASA Astrophysics Data System (ADS)

Zagyvai-Kiss, Katalin Anita; Kalicz, Péter; Csáfordi, Péter; Kucsara, Mihály; Gribovszki, Zoltán

2013-04-01

Precipitation is trapped and temporarily stored by the surfaces of forest crown (canopy interception) and forest litter (litter interception). The stemflow and throughfall reach the litter, thus theoretically the litter moisture content depends on these parts of precipitation. Nowadays the moisture pattern of the forest floor, both spatial and temporal scale, have growing respect for the forestry. The transition to the continuous cover forestry induce much higher variability compared to the even aged, more-less homogeneous, monocultural stands. The gap cutting is one of the key methods in the Hungarian forestry. There is an active discussion among the forest professionals how to determine the optimal gap size to maintain the optimal conditions for the seedlings. Among the open questions is how to modify surrounding trees the moisture pattern of the forest floor in the gap? In the early steps of a multidisciplinary project we processed some available data, to estimate the spatial dependency between the water content of forest litter and the spatial pattern of the canopy represented by the tree trunk. The maximum water content depends on dry weight of litter, thus we also analysed that parameter. Data were measured in three different forest ecosystems: a middle age beech (Fagus sylvatica), a sessile oak (Quercus petraea) and a spruce (Picea abies) stand. The study site (Hidegvíz Valley Research Cathcment) is located in Sopron Hills at the eastern border of the Alps. Litter samples were collected under each stand (occasionally 10-10 pieces from 40?40 cm area) and locations of the samples and neighbouring trees were mapped. We determined dry weight and the water content of litter in laboratory. The relationship between water content and the distance of tree trunks in case of spruce and oak stands were not significant and in case of the beech stand was weakly significant. Climate change effects can influence significantly forest floor moisture content, therefore this factor has also taken into account. Acknowledgement: The research was financially supported by the TÁMOP-4.2.2.A-11/1/KONV-2012-0004 and TÁMOP-4.2.2.A-11/1/KONV-2012-0013 joint EU-national research projects.

Investigation of the spatial variability and possible origins of wind-induced air pressure fluctuations responsible for pressure pumping

NASA Astrophysics Data System (ADS)

Mohr, Manuel; Laemmel, Thomas; Maier, Martin; Zeeman, Matthias; Longdoz, Bernard; Schindler, Dirk

2017-04-01

The exchange of greenhouse gases between the soil and the atmosphere is highly relevant for the climate of the Earth. Recent research suggests that wind-induced air pressure fluctuations can alter the soil gas transport and therefore soil gas efflux significantly. Using a newly developed method, we measured soil gas transport in situ in a well aerated forest soil. Results from these measurements showed that the commonly used soil gas diffusion coefficient is enhanced up to 30% during periods of strong wind-induced air pressure fluctuations. The air pressure fluctuations above the forest floor are only induced at high above-canopy wind speeds (> 5 m s-1) and lie in the frequency range 0.01-0.1 Hz. Moreover, the amplitudes of air pressure fluctuations in this frequency range show a clear quadratic dependence on mean above-canopy wind speed. However, the origin of these wind-induced pressure fluctuations is still unclear. Airflow measurements and high-precision air pressure measurements were conducted at three different vegetation-covered sites (conifer forest, deciduous forest, grassland) to investigate the spatial variability of dominant air pressure fluctuations, their origin and vegetation-dependent characteristics. At the conifer forest site, a vertical profile of air pressure fluctuations was measured and an array consisting of five pressure sensors were installed at the forest floor. At the grassland site, the air pressure measurements were compared with wind observations made by ground-based LIDAR and spatial temperature observations from a fibre-optic sensing network (ScaleX Campaign 2016). Preliminary results show that at all sites the amplitudes of relevant air pressure fluctuations increase with increasing wind speed. Data from the array measurements reveal that there are no time lags between the air pressure signals of different heights, but a time lag existed between the air pressure signals of the sensors distributed laterally on the forest floor, suggesting a horizontal propagation of the air pressure waves.

Variation of biomass and carbon pools with forest type in temperate forests of Kashmir Himalaya, India.

PubMed

Dar, Javid Ahmad; Sundarapandian, Somaiah

2015-02-01

An accurate characterization of tree, understory, deadwood, floor litter, and soil organic carbon (SOC) pools in temperate forest ecosystems is important to estimate their contribution to global carbon (C) stocks. However, this information on temperate forests of the Himalayas is lacking and fragmented. In this study, we measured C stocks of tree (aboveground and belowground biomass), understory (shrubs and herbaceous), deadwood (standing and fallen trees and stumps), floor litter, and soil from 111 plots of 50 m × 50 m each, in seven forest types: Populus deltoides (PD), Juglans regia (JR), Cedrus deodara (CD), Pinus wallichiana (PW), mixed coniferous (MC), Abies pindrow (AP), and Betula utilis (BU) in temperate forests of Kashmir Himalaya, India. The main objective of the present study is to quantify the ecosystem C pool in these seven forest types. The results showed that the tree biomass ranged from 100.8 Mg ha(-1) in BU forest to 294.8 Mg ha(-1) for the AP forest. The understory biomass ranged from 0.16 Mg ha(-1) in PD forest to 2.36 Mg ha(-1) in PW forest. Deadwood biomass ranged from 1.5 Mg ha(-1) in PD forest to 14.9 Mg ha(-1) for the AP forest, whereas forest floor litter ranged from 2.5 Mg ha(-1) in BU and JR forests to 3.1 Mg ha(-1) in MC forest. The total ecosystem carbon stocks varied from 112.5 to 205.7 Mg C ha(-1) across all the forest types. The C stocks of tree, understory, deadwood, litter, and soil ranged from 45.4 to 135.6, 0.08 to 1.18, 0.7 to 6.8, 1.1 to 1.4, and 39.1-91.4 Mg ha(-1), respectively, which accounted for 61.3, 0.2, 1.4, 0.8, and 36.3 % of the total carbon stock. BU forest accounted 65 % from soil C and 35 % from biomass, whereas PD forest contributed only 26 % from soil C and 74 % from biomass. Of the total C stock in the 0-30-cm soil, about 55 % was stored in the upper 0-10 cm. Soil C stocks in BU forest were significantly higher than those in other forests. The variability of C pools of different ecosystem components is influenced by vegetation type, stand structure, management history, and altitude. Our results reveal that a higher percentage (63 %) of C is stored in biomass and less in soil in these temperate forests except at the higher elevation broad-leaved BU forest. Results from this study will enhance our ability to evaluate the role of these forests in regional and global C cycles and have great implications for planning strategies for conservation. The study provides important data for developing and validating C cycling models for temperate forests.

Forest wildfire increases soil microbial biomass C:N:P stoichiometry in long-term effects

NASA Astrophysics Data System (ADS)

Zhou, Xuan

2017-04-01

Boreal forest fire strongly influences carbon (C) stock in permafrost soil by thawing permafrost table which accelerated microbe decomposition process. We studied soil microbial biomass stoichiometry in a gradient of four (3 yr, 25 yr, 46 yr and more than 100 yr) ages since fire in Canada boreal forest. Soil microbial biomass (MB) in long-term after fire is significantly higher than in short-term. MB C and nitrogen (N) were mainly dominated by corresponding soil element concentration and inorganic P, while MB phosphorus (P) changes were fully explained by soil N. Fire ages and soil temperature positively increased MB N and P, indicating the negative impact by fire. Microbial C:N:P gradually increased with fire ages from 15:2:1 to 76:6:1 and then drop down to 17:2:1 in the oldest fire ages. The degree of homeostasis of microbial C, N and P are close to 1 indicates non-homoeostasis within microbial elements, while it of C:N:P is close to 8 shows a strong homeostasis within element ratios and proved microbial stoichiometric ratio is not driven by soil element ratios. In conclusion, i) microbial biomass elements highly depends on soil nutrient supply rather than fire ages; ii) wildfire decreased microbial stoichiometry immediate after fire but increased with years after fire (YF) which at least 3 times higher than > 100 fire ages; iii) microbial biomass C, N and P deviated from strict homeostasis but C:N:P ratio reflects stronger homeostasis.

Spatial P heterogeneity in forest soil: Influence on microbial P uptake and community structure

NASA Astrophysics Data System (ADS)

Zilla, Thomas; Angulo-Schipper, Bridith; Méndez, Juan Carlos; Dippold, Michaela A.; Kuzyakov, Yakov; Spielvogel, Sandra

2017-04-01

Other than nitrogen, phosphorus (P) is the most important growth limiting nutrient in soils. Yet, little information is available concerning the spatial heterogeneity of P content in forest soils. More so, the effects of a homogeneous vs. heterogeneous soil P distribution on microbial P acquisition and community structure have yet to be determined. Thus, a rhizotron experiment based on a P-deficient forest soil was conducted to investigate competitive P uptake strategies of microbes. F. sylvatica-bearing rhizotrons were labeled with Fe33PO4, a relatively immobile P source native to the study soil. Homogeneous and heterogeneous P patterns were created to study the effects of spatial P heterogeneity on plant and microbial P acquisition. P mobilization by microorganisms was tracked by an improved 33P-PLFA method, linking 33P incorporation in microbes with changes in microbial community structure in soils in situ. The microbial P uptake was enhanced in rhizotrons with high P availability and in those with a patchy P distribution. Characteristic PLFAs indicate a congregation of beech-associated ectomycorrhizal fungi in P-rich patches. These ectomycorrhizal fungi are likely to strongly increase P mobilization from the used Fe33PO4 in high P habitats. In contrast, habitats with low P availability require a more complex microbial community structure without a dominant group to mobilize this inaccessible P source. Therefore, hotspots of P are likely to promote the efforts of fungal hyphae for P mobilization - an effect which decreases with lower P content. Additionally, gram positive and negative bacteria exhibit a vastly higher P uptake under increasingly patchy P distributions. However, they form a smaller portion of the microbial community than in homogeneously P enriched rhizotrons, suggesting that filamentous organisms benefit from the patchy P distribution. Thus, only a heterogeneous P distribution promotes P acquisition of forest microbial communities from mineral P sources with low bioavailability. These novel insights into the effects of spatial P distributions on forest soil community dynamics will hopefully shed further light on microbial P cycling, thereby helping to tackle the impending global P crisis.|

Biogeography and organic matter removal shape long-term effects of timber harvesting on forest soil microbial communities.

PubMed

Wilhelm, Roland C; Cardenas, Erick; Maas, Kendra R; Leung, Hilary; McNeil, Larisa; Berch, Shannon; Chapman, William; Hope, Graeme; Kranabetter, J M; Dubé, Stephane; Busse, Matt; Fleming, Robert; Hazlett, Paul; Webster, Kara L; Morris, David; Scott, D Andrew; Mohn, William W

2017-11-01

The growing demand for renewable, carbon-neutral materials and energy is leading to intensified forest land-use. The long-term ecological challenges associated with maintaining soil fertility in managed forests are not yet known, in part due to the complexity of soil microbial communities and the heterogeneity of forest soils. This study determined the long-term effects of timber harvesting, accompanied by varied organic matter (OM) removal, on bacterial and fungal soil populations in 11- to 17-year-old reforested coniferous plantations at 18 sites across North America. Analysis of highly replicated 16 S rRNA gene and ITS region pyrotag libraries and shotgun metagenomes demonstrated consistent changes in microbial communities in harvested plots that included the expansion of desiccation- and heat-tolerant organisms and decline in diversity of ectomycorrhizal fungi. However, the majority of taxa, including the most abundant and cosmopolitan groups, were unaffected by harvesting. Shifts in microbial populations that corresponded to increased temperature and soil dryness were moderated by OM retention, which also selected for sub-populations of fungal decomposers. Biogeographical differences in the distribution of taxa as well as local edaphic and environmental conditions produced substantial variation in the effects of harvesting. This extensive molecular-based investigation of forest soil advances our understanding of forest disturbance and lays the foundation for monitoring long-term impacts of timber harvesting.

Influences of disturbance and vegetation on abundance of native and exotic detritivores in a southwestern riparian forest

Treesearch

D. Max Smith; Jeffrey F. Kelly; Deborah M. Finch

2006-01-01

Detritivores play important roles in energy and nutrient flow in riparian ecosystems. Endemic crickets (Gryllus alogus Rehn) and exotic isopods (Armadillidium vulagare Latreille and Porcellio laevi Latreille.) are abundant detritivores in riparian forest floors of central New Mexico. To determine how disturbance...

Legacy retention versus thinning: influences on small mammals.

Treesearch

S.M. Wilson; A.B. Carey

2000-01-01

Management strategies for promoting late-seral attributes in second-growth forest need evaluation for their efficacy in maintaining biodiversity, including complete forest-floor, small-mammal communities. Two common strategies in the Pacific Northwest are (1) management with thinnings to promote large trees with developed understories and (2) retention of legacies,...

Transverse vibration technique to identify deteriorated wood floor systems

Treesearch

R.J. Ross; X. Wang; M.O. Hunt; L.A. Soltis

2002-01-01

The Forest Products Laboratory, USDA Forest Service, has been developing nondestructive evaluation (NDE) techniques to identify degradation of wood in structures and the performance characteristics that remain in the structure. This work has focused on using dynamic testing techniques, particularly stress wave and ultrasonic transmission NDE techniques for both...

Headwater riparian forest-floor invertebrate communities associated with alternative forest management practices.

Treesearch

J.J. Rykken; A.R. Moldenke; D.H. Olson

2007-01-01

Invertebrate communities were characterized in unmanaged headwaters, and the effects of clearcutting without buffers and with buffers of approximately 30 m was examined. A near-stream community was distinct and largely retained by the buffers. Elevation, location, and microclimate were predictors of community structure.

SOIL TYPE AND FOREST VEGETATION INFLUENCES ON FOREST FLOOR NITROGEN DYNAMICS AT THE BEAR BROOK WATERSHED IN MAINE. (R825762)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Upland Trees Contribute to Exchange of Nitrous Oxide (N2O) in Forest Ecosystems

NASA Astrophysics Data System (ADS)

Tian, H.; Thompson, R.; Canadell, J.; Winiwarter, W.; Machacova, K.; Maier, M.; Halmeenmäki, E.; Svobodova, K.; Lang, F.; Pihlatie, M.; Urban, O.

2017-12-01

The increase in atmospheric nitrous oxide (N2O) concentration contributes to the acceleration of the greenhouse effect. However, the role of trees in the N2O exchange of forest ecosystems is still an open question. While the soils of temperate and boreal forests were shown to be a natural source of N2O, trees have been so far overlooked in the forest N2O inventories. We determined N2O fluxes in common tree species of boreal and temperate forests: Scots pine (Pinus sylvestris), Norway spruce (Picea abies), downy and silver birch (Betula pubescens, B. pendula), and European beech (Fagus sylvatica). We investigated (1) whether these tree species exchange N2O with the atmosphere under natural field conditions, (2) how the tree N2O fluxes contribute to the forest N2O balance, and (3) whether these fluxes show seasonal dynamics. The studies were performed in a boreal forest (SMEAR II station, Finland; June 2014 - May 2015) and two temperate mountain forests (White Carpathians, Czech Republic; Black Forest, Germany; June and July 2015). Fluxes of N2O in mature tree stems and forest floor were measured using static chamber systems followed by chromatographic and photo-acoustic analyses of N2O concentration changes. Pine, spruce and birch trees were identified as net annual N2O sources. Spruce was found the strongest emitter (0.27 mg ha-1 h-1) amounting thus up to 2.5% of forest floor N2O emissions. All tree species showed a substantial seasonality in stem N2O flux that was related to their physiological activity and climatic variables. In contrast, stems of beech trees growing at soils consuming N2O may act as a substantial sink of N2O from the atmosphere. Consistent N2O consumption by tree stems ranging between -12.1 and -35.2 mg ha-1 h-1 and contributing by up to 3.4% to the forest floor N2O uptake is a novel finding in contrast to current studies presenting trees as N2O emitters. To understand these fluxes, N2O exchange of photoautotrophic organisms associated with beech bark (lichens, mosses and algae) was quantified. All the organisms were net N2O sinks at full rehydration with consumption rates comparable to stem consumption rates. All tree species studied contribute to N2O exchange in forest ecosystems and these fluxes have to be included in the forest N2O emission inventories.

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 compaction and organic matter affect conifer seedling nonmycorrhizal and ectomycorrhizal root tip abundance and diversity. Forest Service research paper

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

Amaranthus, M.P.; Page-Dumroese, D.; Harvey, A.

1996-05-01

Three levels of organic matter removal (bole only; bole and crowns; and bole, crowns, and forest floor) and three levels of mechanical soil compaction (no compaction, moderate compaction, and severe soil compaction) were studied as they influence Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) and western white pine (Pinus monticola Dougl. ex D. Don) seedlings following outplanting. Moderate and severe soil compaction significantly reduced nonmycorrhizal root tip abundance on both Douglas-fir and western white pine seedlings (p less than or equal to 0.05). Ectomycorrhizal root tip abundance was significantly reduced on Douglas-fir seedlings in severely compacted areas with bole andmore » crowns and bole, crowns, and forest floor removed. Ectomycorrhizal diversity also was significantly reduced on Douglas-fir seedlings in all severely compacted areas.« less

Retention of potentially mobile radiocesium in forest surface soils affected by the Fukushima nuclear accident

PubMed Central

Koarashi, Jun; Moriya, Koichi; Atarashi-Andoh, Mariko; Matsunaga, Takeshi; Fujita, Hiroki; Nagaoka, Mika

2012-01-01

The fate of 137Cs derived from the Fukushima nuclear accident fallout and associated radiological hazards are largely dependent on its mobility in the surface soils of forest ecosystems. Thus, we quantified microbial and adsorptive retentions of 137Cs in forest surface (0–3 cm) soils. The K2SO4 extraction process liberated 2.1%–12.8% of the total 137Cs from the soils. Two soils with a higher content of clay- and silt-sized particles, organic carbon content, and cation exchange capacity showed higher 137Cs extractability. Microbial biomass was observed in all of the soils. However, the 137Cs extractability did not increase after destruction of the microbial biomass by chloroform fumigation, providing no evidence for microbial retention of the Fukushima-fallout 137Cs. The results indicate that uptake of 137Cs by soil microorganisms is less important for retention of potentially mobile 137Cs in the forest surface soils compared to ion-exchange adsorption on non-specific sites provided by abiotic components. PMID:23256039

Relating microbial community structure to functioning in forest soil organic carbon transformation and turnover.

PubMed

You, Yeming; Wang, Juan; Huang, Xueman; Tang, Zuoxin; Liu, Shirong; Sun, Osbert J

2014-03-01

Forest soils store vast amounts of terrestrial carbon, but we are still limited in mechanistic understanding on how soil organic carbon (SOC) stabilization or turnover is controlled by biotic and abiotic factors in forest ecosystems. We used phospholipid fatty acids (PLFAs) as biomarker to study soil microbial community structure and measured activities of five extracellular enzymes involved in the degradation of cellulose (i.e., β-1,4-glucosidase and cellobiohydrolase), chitin (i.e., β-1,4-N-acetylglucosaminidase), and lignin (i.e., phenol oxidase and peroxidase) as indicators of soil microbial functioning in carbon transformation or turnover across varying biotic and abiotic conditions in a typical temperate forest ecosystem in central China. Redundancy analysis (RDA) was performed to determine the interrelationship between individual PFLAs and biotic and abiotic site factors as well as the linkage between soil microbial structure and function. Path analysis was further conducted to examine the controls of site factors on soil microbial community structure and the regulatory pathway of changes in SOC relating to microbial community structure and function. We found that soil microbial community structure is strongly influenced by water, temperature, SOC, fine root mass, clay content, and C/N ratio in soils and that the relative abundance of Gram-negative bacteria, saprophytic fungi, and actinomycetes explained most of the variations in the specific activities of soil enzymes involved in SOC transformation or turnover. The abundance of soil bacterial communities is strongly linked with the extracellular enzymes involved in carbon transformation, whereas the abundance of saprophytic fungi is associated with activities of extracellular enzymes driving carbon oxidation. Findings in this study demonstrate the complex interactions and linkage among plant traits, microenvironment, and soil physiochemical properties in affecting SOC via microbial regulations.

Floors and Toilets: Association of Floors and Sanitation Practices with Fecal Contamination in Peruvian Amazon Peri-Urban Households.

PubMed

Exum, Natalie G; Olórtegui, Maribel Paredes; Yori, Pablo Peñataro; Davis, Meghan F; Heaney, Christopher D; Kosek, Margaret; Schwab, Kellogg J

2016-07-19

Over two billion people worldwide lack access to an improved sanitation facility that adequately retains or treats feces. This results in the potential for fecal material containing enteric pathogens to contaminate the environment, including household floors. This study aimed to assess how floor type and sanitation practices impacted the concentration of fecal contamination on household floors. We sampled 189 floor surfaces within 63 households in a peri-urban community in Iquitos, Peru. All samples were analyzed for colony forming units (CFUs) of E. coli, and households were evaluated for their water, sanitation, and hygiene characteristics. Results of multivariate linear regression indicated that households with improved sanitation and cement floors in the kitchen area had reduced fecal contamination to those with unimproved sanitation and dirt floors (Beta: -1.18 log10 E. coli CFU/900 cm(2); 95% confidence interval [CI]: -1.77, -0.60). Households that did not versus did share their sanitation facility also had less contaminated kitchen floors (Beta: -0.65 log10 E. coli CFU/900 cm(2); 95% CI: -1.15, -0.16). These findings suggest that the sanitation facilities of a home may impact the microbial load found on floors, contributing to the potential for household floors to serve as an indirect route of fecal pathogen transmission to children.

Small-scale spatial heterogeneity of ecosystem properties, microbial community composition and microbial activities in a temperate mountain forest soil.

PubMed

Štursová, Martina; Bárta, Jiří; Šantrůčková, Hana; Baldrian, Petr

2016-12-01

Forests are recognised as spatially heterogeneous ecosystems. However, knowledge of the small-scale spatial variation in microbial abundance, community composition and activity is limited. Here, we aimed to describe the heterogeneity of environmental properties, namely vegetation, soil chemical composition, fungal and bacterial abundance and community composition, and enzymatic activity, in the topsoil in a small area (36 m 2 ) of a highly heterogeneous regenerating temperate natural forest, and to explore the relationships among these variables. The results demonstrated a high level of spatial heterogeneity in all properties and revealed differences between litter and soil. Fungal communities had substantially higher beta-diversity than bacterial communities, which were more uniform and less spatially autocorrelated. In litter, fungal communities were affected by vegetation and appeared to be more involved in decomposition. In the soil, chemical composition affected both microbial abundance and the rates of decomposition, whereas the effect of vegetation was small. Importantly, decomposition appeared to be concentrated in hotspots with increased activity of multiple enzymes. Overall, forest topsoil should be considered a spatially heterogeneous environment in which the mean estimates of ecosystem-level processes and microbial community composition may confound the existence of highly specific microenvironments. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Calcium, potassium, and sodium content of forest floor arthropods

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

Reichle, D.E.; Shanks, M.H.; Crossley, D.A. Jr.

1969-01-01

Whole-body nutrient composition of calcium, potassium, and sodium is documented for 37 species of forest floor arthropods. Sodium concentrations averaging 4.6 mg Na/g ash-free dry weight, and potassium concentrations averaging 6.2 mg K/g ash-free dry weight were relatively consistent within and among major taxonomic categories. Calcium content varied from 0.3 to 509.8 mg Ca/g ash-free dry weight, with highest values associated with Diplopoda and related species possessing highly calcified exoskeletons. Within-species variation in chemical composition often exceeded seasonal fluctuations, although several species exhibited significant temporal changes in whole-body nutrient composition of calcium, potassium, and sodium. 9 references, 3 tables.

Microbial C:P stoichiometry is shaped by redox conditions along an elevation gradient in humid tropical rainforests

NASA Astrophysics Data System (ADS)

Lin, Y.; Gross, A.; Silver, W. L.

2017-12-01

Elemental stoichiometry of microorganisms is intimately related to ecosystem carbon and nutrient fluxes and is ultimately controlled by the chemical (plant tissue, soil, redox) and physical (temperature, moisture, aeration) environment. Previous meta-analyses have shown that the C:P ratio of soil microbial biomass exhibits significant variations among and within biomes. Little is known about the underlying causes of this variability. We examined soil microbial C:P ratios along an elevation gradient in the Luquillo Experimental Forest in Puerto Rico. We analyzed soils from mixed forest paired with monodominant palm forest every 100 m from 300 m to 1000 m a.s.l.. Mean annual precipitation increased with increasing elevation, resulting in stronger reducing conditions and accumulation of soil Fe(II) at higher elevations. The mean value and variability of soil microbial C:P ratios generally increased with increasing elevation except at 1000 m. At high elevations (600-900 m), the average value of microbial C:P ratio (108±10:1) was significantly higher than the global average ( 55:1). We also found that soil organic P increased with increasing elevation, suggesting that an inhibition of organic P mineralization, not decreased soil P availability, may cause the high microbial C:P ratio. The soil microbial C:P ratio was positively correlated with soil HCl-extractable Fe(II), suggesting that reducing conditions may be responsible for the elevational changes observed. In a follow-up experiment, soils from mixed forests at four elevation levels (300, 500, 700, and 1000 m) were incubated under aerobic and anaerobic conditions for two weeks. We found that anaerobic incubation consistently increased the soil microbial C:P ratio relative to the aerobic incubation. Overall, our results indicate that redox conditions can shift the elemental composition of microbial biomass. The high microbial C:P ratios induced under anoxic conditions may reflect inhibition of microbial P mineralization and/or immobilization under reducing conditions. These results will help us to better understand the patterns of nutrient cycling and microbial activity across macro-scale environmental gradients.

Anoxic conditions drive phosphorus limitation in humid tropical forest soil microorganisms

NASA Astrophysics Data System (ADS)

Gross, A.; Pett-Ridge, J.; Weber, P. K.; Blazewicz, S.; Silver, W. L.

2017-12-01

The elemental stoichiometry of carbon (C), nitrogen (N) and phosphorus (P) of soil microorganisms (C:N:P ratios) regulates transfers of energy and nutrients to higher trophic levels. In humid tropical forests that grow on P-depleted soils, the ability of microbes to concentrate P from their surroundings likely plays a critical role in P-retention and ultimately in forest productivity. Models predict that climate change will cause dramatic changes in rainfall patterns in the humid tropics and field studies have shown these changes can affect the redox state of tropical forest soils, influencing soil respiration and biogeochemical cycling. However, the responses of soil microorganisms to changing environmental conditions are not well known. Here, we incubated humid tropical soils under oxic or anoxic conditions with substrates differing in both C:P stoichiometry and lability, to assess how soil microorganisms respond to different redox regimes. We found that under oxic conditions, microbial C:P ratios were similar to the global optimal ratio (55:1), indicating most microbial cells can adapt to persistent aerated conditions in these soils. However, under anoxic conditions, the ability of soil microbes to acquire soil P declined and their C:P ratios shifted away from the optimal ratio. NanoSIMS elemental imaging of single cells extracted from soil revealed that under anoxic conditions, C:P ratios were above the microbial optimal value in 83% of the cells, in comparison to 41% under oxic conditions. These data suggest microbial growth efficiency switched from being energy limited under oxic conditions to P-limited under anoxic conditions, indicating that, microbial growth in low P humid tropical forests soils may be most constrained by P-limitation when conditions are oxygen-limited. We suggest that differential microbial responses to soil redox states could have important implications for productivity of humid tropical forests under future climate scenarios.

Grass invasion of a hardwood forest is associated with declines in belowground carbon pools

Treesearch

Michael S. Strickland; Jayna L. Devore; John C. Maerz; Mark A. Bradford

2010-01-01

Invasive plant species affect a range of ecosystem processes but their impact on belowground carbon (C) pools is relatively unexplored. This is particularly true for grass invasions of forested ecosystems. Such invasions may alter both the quantity and quality of forest floor inputs. Dependent on both, two theories, ‘priming’ and ‘preferential substrate utilization’,...

Mechanical mastication as a fuels treatment in southeastern forests

Treesearch

Jesse K. Kreye; J. Morgan Varner; Leda N. Kobziar

2016-01-01

Mastication is an increasingly common fuels treatment that redistributes ‘‘ladder’’ fuels to the forest floor to reduce vertical fuel continuity, crown fire potential, and fireline intensity. Despite its widespread adoption, it remains unclear how mastication impacts fuels, fire behavior, or plant communities  across Southeastern forest ecosystems. We evaluated these...

Dead Trees Bring Life to Forest Critters

Treesearch

Thomas Nicholls; Mike Ostry

2003-01-01

What good is a dying or dead tree in a forest? Dead and dying trees don't awe us with their beauty; they just stand or lie there on the forest floor, offering no promise of lumber or other wood products we need. But if we look more closely at such trees, we may see lots of life in them: a raccoon family huddled in a burrow, a downy woodpecker excavating another...

Effects of prescribed fire intervals on carbon and nitrogen in forest soils of the Mogollon Rim, Arizona

Treesearch

Daniel G. Neary; Steven T. Overby; Sally M. Haase

2003-01-01

The pre-European settlement ponderosa pine forests of the Mogollon Rim consisted of open stands of uneven-aged trees with a significant grass-forb understory. Light surface-fires occurred on an average interval of 2 to 12 years in Arizona and New Mexico (Dietrich 1980). These fires consumed forest floor material, burned most of the young regeneration, and promoted...

Climate change-driven treeline advances in the Urals alter soil microbial communities

NASA Astrophysics Data System (ADS)

Djukic, Ika; Moiseev, Pavel; Hagedorn, Frank

2016-04-01

Climatic warming may affect microbial communities and their functions either directly through increased temperatures or indirectly by changes in vegetation. Treelines are temperature-limited vegetation boundaries from tundra to forests. In unmanaged regions of the Ural mountains, there is evidence that the forest-tundra ecotone has shifted upward in response to climate warming during the 20th century. Little is known about the effects of the treeline advances on the microbial structure and function and hence they feedbacks on the belowground carbon and nitrogen cycling In our study, we aimed to estimate how ongoing upward shifts of the treeline ecotone might affect soil biodiversity and its function and hence soil carbon (C) and nitrogen (N) dynamics in the Southern and Polar Ural mountains. Along altitudinal gradients reaching from the tundra to forests, we determined the soil microbial community composition (using Phospholipid Fatty Acids method) and quantified the activity of several extracellular enzymes involved in the C and nutrient cycling. In addition, we measured C pools in biomass and soils and quantified C and N mineralization. The results for the top soils, both in South Urals and in the Polar Ural, indicate a close link between climate change driven vegetation changes and soil microbial communities. The observed changes in microbial structure are induced through the resulting more favorable conditions than due to a shift in litter quality. The activities of chitinase were significantly higher under trees than under herbaceous plants, while activities of cellulase and protease declined with altitude from the tundra to the closed forest. In contrast to enzymatic activities, soil carbon stocks did not change significantly with altitude very likely as a result of a balancing out of increased C inputs from vegetation by an enhanced C output through mineralization with forest expansion. The accelerated organic matter turnover in the forest than in the tundra leads to higher contents of mineral N and net nitrification rates. In turn, the increasing N availability may stimulate plant growth and hence, induce a positive feedback between treeline advances and soil nitrogen cycling through soil microbial communities.

Variability of albedo and utility of the MODIS albedo product in forested wetlands

USGS Publications Warehouse

Sumner, David M.; Wu, Qinglong; Pathak, Chandra S.

2011-01-01

Albedo was monitored over a two-year period (beginning April 2008) at three forested wetland sites in Florida, USA using up- and down-ward facing pyranometers. Water level, above and below land surface, is the primary control on the temporal variability of daily albedo. Relatively low reflectivity of water accounts for the observed reductions in albedo with increased inundation of the forest floor. Enhanced canopy shading of the forest floor was responsible for lower sensitivity of albedo to water level at the most dense forest site. At one site, the most dramatic reduction in daily albedo was observed during the inundation of a highly-reflective, calcareous periphyton-covered land surface. Satellite-based Moderate-Resolution Imaging Spectroradiometer (MODIS) estimates of albedo compare favorably with measured albedo. Use of MODIS albedo values in net radiation computations introduced a root mean squared error of less than 4.7 W/m2 and a mean, annual bias of less than 2.3 W/m2 (1.7%). These results suggest that MODIS-estimated albedo values can reliably be used to capture areal and temporal variations in albedo that are important to the surface energy balance.

Comparison of methods to control floor contamination in an animal research facility.

PubMed

Allen, Kenneth P; Csida, Tarrant; Leming, Jeaninne; Murray, Kathleen; Gauld, Stephen B; Thulin, Joseph

2012-10-01

The authors evaluated the effectiveness of adhesive mats, contamination control flooring, and shoe covers in decreasing the presence of microbial agents on animal holding room floors and footwear. Swab samples taken from animal holding room floors after the use of each product were compared with samples taken from rooms after no products were used. Swab samples were also taken from the heels and soles of the footwear of animal care staff before and after use of each product. The use of contamination control flooring or shoe covers significantly reduced the amount of organic material (as indicated by ATP levels measured by a luminometer) present on floors. Bacterial and ATP contamination of footwear was significantly lower after the use of shoe covers than after the use of adhesive mats or contamination control flooring, and the use of shoe covers led to a greater decrease in contamination before and after use than did use of either of the other two products. Although shoe covers were superior to both adhesive mats and contamination control flooring for decreasing contamination of animal room floors and footwear, facilities must take into account the contamination control standards required, the cost of the product, and the labor and time associated with product use when deciding which contamination control practices to implement.

Does long-term elevation of CO{sub 2} concentration increase photosynthesis in forest floor vegetation? Indiana strawberry in a Maryland forest

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

Osborne, C.P.; Long, S.P.; Drake, B.G.

1997-05-01

As the partial pressure of CO{sub 2} (pCO{sub 2}) in the atmosphere rises, photorespiratory loss of carbon in C, photosynthesis will diminish and the net efficiency of light-limited photosynthetic carbon uptake should rise. Indiana strawberry (Duchesnea indica) growing on a Maryland forest floor was tested. Open-top chambers were used to elevate the pCO{sub 2} of a forest floor habitat to 67 Pa and were paired with control chambers with an ambient pCO{sub 2} of 38 Pa. After 3.5 years, D. indica leaves in the elevated pCO{sub 2} showed a significantly greater maximum quantum efficiency of net photosynthesis (by 22%) andmore » a lower light compensation point (by 42%) than leaves in the control chambers. The quantum efficiency to minimize photorespiration was the same for controls and plants grown at elevated pCO{sub 2}, showing the maximum efficiency of light-energy transduction into assimilated carbon was not altered by acclimation and the increase in light-limited photosynthesis at elevated pCO{sub 2} was a function of the decrease in photorespiration. Acclimation did decrease the ribulose-1,5-bisphosphate carboxylase/oxygenase and light-harvesting chlorophyll protein content of the leaf by more than 30%. These changes were associated with a decreased capacity for light-saturated, but not light-limited, photosynthesis. Leaves of D. indica grown and measured at elevated pCO{sub 2} showed greater light-saturated photosynthetic rates than leaves grown and measured at the current atmospheric pCO{sub 2}. In situ measurements under natural lighting showed large increases in leaf photosynthesis at elevated pCO{sub 2}, relative to controls, in both summer and fall. The increase in efficiency of light-limited photosynthesis with elevated pCO{sub 2} allowed positive net photosynthetic carbon uptake on days and at locations on the forest floor that light fluxes were insufficient for positive net photosynthesis in the current atmospheric pCO{sub 2}. 33 refs., 3 figs., 3 tabs.« less

Cruising the rain forest floor: butterfly wing shape evolution and gliding in ground effect.

PubMed

Cespedes, Ann; Penz, Carla M; DeVries, Philip J

2015-05-01

Flight is a key innovation in the evolutionary success of insects and essential to dispersal, territoriality, courtship and oviposition. Wing shape influences flight performance and selection likely acts to maximize performance for conducting essential behaviours that in turn results in the evolution of wing shape. As wing shape also contributes to fitness, optimal shapes for particular flight behaviours can be assessed with aerodynamic predictions and placed in an ecomorphological context. Butterflies in the tribe Haeterini (Nymphalidae) are conspicuous members of understorey faunas in lowland Neotropical forests. Field observations indicate that the five genera in this clade differ in flight height and behaviour: four use gliding flight at the forest floor level, and one utilizes flapping flight above the forest floor. Nonetheless, the association of ground level gliding flight behaviour and wing shape has never been investigated in this or any other butterfly group. We used landmark-based geometric morphometrics to test whether wing shapes in Haeterini and their close relatives reflected observed flight behaviours. Four genera of Haeterini and some distantly related Satyrinae showed significant correspondence between wing shape and theoretical expectations in performance trade-offs that we attribute to selection for gliding in ground effect. Forewing shape differed between sexes for all taxa, and male wing shapes were aerodynamically more efficient for gliding flight than corresponding females. This suggests selection acts differentially on male and female wing shapes, reinforcing the idea that sex-specific flight behaviours contribute to the evolution of sexual dimorphism. Our study indicates that wing shapes in Haeterini butterflies evolved in response to habitat-specific flight behaviours, namely gliding in ground effect along the forest floor, resulting in ecomorphological partitions of taxa in morphospace. The convergent flight behaviour and wing morphology between tribes of Satyrinae suggest that the flight environment may offset phylogenetic constraints. Overall, this study provides a basis for exploring similar patterns of wing shape evolution in other taxa that glide in ground effect. © 2014 The Authors. Journal of Animal Ecology © 2014 British Ecological Society.

The response of ecosystem carbon pools to management approaches in loblolly pine (Pinus taeda L.) plantations

NASA Astrophysics Data System (ADS)

Vogel, J. G.; Bacon, A. R.; Bracho, R. G.; Gonzalez-Benecke, C. A.; Fox, T. D.; Laviner, M. A.; Kane, M.; Burkhart, H.; Martin, T.; Will, R.; Ross, C. W.; Grunwald, S.; Jokela, E. J.; Meek, C.

2016-12-01

Extending from Virginia to east Texas in the southeastern United States, managed pine plantations are an important component of the region's carbon cycle. An objective of the Pine Integrated Network: Education, Mitigation, and Adaptation project (PINEMAP) is to improve estimates of how ecosystem carbon pools respond to the management strategies used to increase the growth of loblolly pine plantations. Experimental studies (108 total) that have been used to understand plantation productivity and stand dynamics by university-forest industry cooperatives were measured for the carbon stored in the trees, roots, coarse-wood, detritus in soil, forest floor, understory and soils to 1-meter. The age of the studied plantations ranged from 4-26 years at the time of sampling, with 26 years very near the period when these plantations are commonly harvested. Across all study sites, 455 experimental plots were measured. The average C storage across all pools, sites, and treatments was 192 Mg C ha-1, with the average percentage of the total coming from soil (44%), tree biomass (40%), forest floor (8%), root (5%), soil detritus (2%), understory biomass (1%), and coarse-wood (<1%) pools. Plots had as a treatment either fertilization, competition control, and stand density control (thinning), and every possible combination of treatments including `no treatment'. A paired plot analysis was used where two plots at a site were examined for relative differences caused by a single treatment and these differences averaged across the region. Thinning as a stand-alone treatment significantly reduced forest floor mass by 60%, and the forest floor in the thinned plus either competition control or fertilization was 18.9% and 19.2% less, respectively, than unthinned stands combined with the same treatments. Competition control increased C storage in tree biomass by 12% and thinning decreased tree biomass by 32%. Thinning combined with fertilization had lower soil carbon (0-1 m) than unthinned-fertilized plots (22%), although the replication for this combination was relatively low (n=6). Overall these results suggest that maintaining higher tree densities increases ecosystem carbon storage across multiple pools of C in loblolly pine plantations.

Distribution of black carbon in ponderosa pine forest floor and soils following the High Park wildfire

NASA Astrophysics Data System (ADS)

Boot, C. M.; Haddix, M.; Paustian, K.; Cotrufo, M. F.

2015-05-01

Biomass burning produces black carbon (BC), effectively transferring a fraction of the biomass C from an actively cycling pool to a passive C pool, which may be stored in the soil. Yet the timescales and mechanisms for incorporation of BC into the soil profile are not well understood. The High Park fire (HPF), which occurred in northwestern Colorado in the summer of 2012, provided an opportunity to study the effects of both fire severity and geomorphology on properties of carbon (C), nitrogen (N) and BC in the Cache La Poudre River drainage. We sampled montane ponderosa pine forest floor (litter plus O-horizon) and soils at 0-5 and 5-15 cm depth 4 months post-fire in order to examine the effects of slope and burn severity on %C, C stocks, %N and BC. We used the benzene polycarboxylic acid (BPCA) method for quantifying BC. With regard to slope, we found that steeper slopes had higher C : N than shallow slopes but that there was no difference in BPCA-C content or stocks. BC content was greatest in the forest floor at burned sites (19 g BPCA-C kg-1 C), while BC stocks were greatest in the 5-15 cm subsurface soils (23 g BPCA-C m-2). At the time of sampling, unburned and burned soils had equivalent BC content, indicating none of the BC deposited on the land surface post-fire had been incorporated into either the 0-5 or 5-15 cm soil layers. The ratio of B6CA : total BPCAs, an index of the degree of aromatic C condensation, suggested that BC in the 5-15 cm soil layer may have been formed at higher temperatures or experienced selective degradation relative to the forest floor and 0-5 cm soils. Total BC soil stocks were relatively low compared to other fire-prone grassland and boreal forest systems, indicating most of the BC produced in this system is likely lost, either through erosion events, degradation or translocation to deeper soils. Future work examining mechanisms for BC losses from forest soils will be required for understanding the role BC plays in the global carbon cycle.

Ecological and geochemical impacts of exotic earthworm dispersal in forest ecosystems of Eastern Canada

NASA Astrophysics Data System (ADS)

Drouin, Melanie; Fugere, Martine; Lapointe, Line; Vellend, Mark; Bradley, Robert L.

2016-04-01

In Eastern Canada, native earthworm species did not survive the Wisconsin glaciation, which ended over 11,000 years ago. Accordingly, the 17 known Lumbricidae species in the province of Québec were introduced in recent centuries by European settlers. Given that natural migration rates are no more than 5-10 m yr-1, exotic earthworm dispersal across the landscape is presumed to be mediated by human activities, although this assertion needs further validation. In agroecosystems, earthworms have traditionally been considered beneficial soil organisms that facilitate litter decomposition, increase nutrient availability and improve soil structure. However, earthworm activities could also increase soil nutrient leaching and CO2 emissions. Furthermore, in natural forest ecosystems, exotic earthworms may reduce organic forest floors provoking changes in watershed hydrology and loss of habitat for some faunal species. Over the past decade, studies have also suggested a negative effect of exotic earthworms on understory plant diversity, but the underlying mechanisms remain elusive. Finally, there are no studies to our knowledge that have tested the effects of Lumbricidae species on the production of N2O (an important greenhouse gas) in forest ecosystems. We report on a series of field, greenhouse and laboratory studies on the human activities responsible for the dispersal of exotic earthworms, and on their ecological / geochemical impacts in natural forest ecosystems. Our results show: (1) Car tire treads and bait discarded by fishermen are important human vectors driving the dispersal of earthworms into northern temperate forests; (2) Exotic earthworms significantly modify soil physicochemical properties, nutrient cycling, microbial community structure and biomass; (3) Earthworm abundances in the field correlate with a decrease in understory plant diversity; (4) Lumbricus terrestris, an anecic earthworm species and favorite bait of fishermen, reduces seed germination and seedling survival of some temperate and boreal trees species; (5) The abundance of L. terrestris correlates with higher potential rates of N2O production. Taken collectively, our data provide scientific evidence that earthworm dispersal mitigation strategies are required to conserve the ecological integrity of forest ecosystems in Eastern Canada.

Quantifying the missing link between forest albedo and productivity in the boreal zone

NASA Astrophysics Data System (ADS)

Hovi, Aarne; Liang, Jingjing; Korhonen, Lauri; Kobayashi, Hideki; Rautiainen, Miina

2016-11-01

Albedo and fraction of absorbed photosynthetically active radiation (FAPAR) determine the shortwave radiation balance and productivity of forests. Currently, the physical link between forest albedo and productivity is poorly understood, yet it is crucial for designing optimal forest management strategies for mitigating climate change. We investigated the relationships between boreal forest structure, albedo and FAPAR using a radiative transfer model called Forest Reflectance and Transmittance model FRT and extensive forest inventory data sets ranging from southern boreal forests to the northern tree line in Finland and Alaska (N = 1086 plots). The forests in the study areas vary widely in structure, species composition, and human interference, from intensively managed in Finland to natural growth in Alaska. We show that FAPAR of tree canopies (FAPARCAN) and albedo are tightly linked in boreal coniferous forests, but the relationship is weaker if the forest has broadleaved admixture, or if canopies have low leaf area and the composition of forest floor varies. Furthermore, the functional shape of the relationship between albedo and FAPARCAN depends on the angular distribution of incoming solar irradiance. We also show that forest floor can contribute to over 50 % of albedo or total ecosystem FAPAR. Based on our simulations, forest albedos can vary notably across the biome. Because of larger proportions of broadleaved trees, the studied plots in Alaska had higher albedo (0.141-0.184) than those in Finland (0.136-0.171) even though the albedo of pure coniferous forests was lower in Alaska. Our results reveal that variation in solar angle will need to be accounted for when evaluating climate effects of forest management in different latitudes. Furthermore, increasing the proportion of broadleaved trees in coniferous forests is the most important means of maximizing albedo without compromising productivity: based on our findings the potential of controlling forest density (i.e., basal area) to increase albedo may be limited compared to the effect of favoring broadleaved species.

Interactive Effects of Nitrogen and Phosphorus on Soil Microbial Communities in a Tropical Forest

PubMed Central

Liu, Lei; Zhang, Tao; Gilliam, Frank S.; Gundersen, Per; Zhang, Wei; Chen, Hao; Mo, Jiangming

2013-01-01

Elevated nitrogen (N) deposition in humid tropical regions may exacerbate phosphorus (P) deficiency in forests on highly weathered soils. However, it is not clear how P availability affects soil microbes and soil carbon (C), or how P processes interact with N deposition in tropical forests. We examined the effects of N and P additions on soil microbes and soil C pools in a N-saturated old-growth tropical forest in southern China to test the hypotheses that (1) N and P addition will have opposing effects on soil microbial biomass and activity, (2) N and P addition will alter the composition of the microbial community, (3) the addition of N and P will have interactive effects on soil microbes and (4) addition-mediated changes in microbial communities would feed back on soil C pools. Phospholipid fatty acid (PLFA) analysis was used to quantify the soil microbial community following four treatments: Control, N addition (15 g N m−2 yr−1), P addition (15 g P m−2 yr−1), and N&P addition (15 g N m−2 yr−1 plus 15 g P m−2 yr−1). These were applied from 2007 to 2011. Whereas additions of P increased soil microbial biomass, additions of N reduced soil microbial biomass. These effects, however, were transient, disappearing over longer periods. Moreover, N additions significantly increased relative abundance of fungal PLFAs and P additions significantly increased relative abundance of arbuscular mycorrhizal (AM) fungi PLFAs. Nitrogen addition had a negative effect on light fraction C, but no effect on heavy fraction C and total soil C. In contrast, P addition significantly decreased both light fraction C and total soil C. However, there were no interactions between N addition and P addition on soil microbes. Our results suggest that these nutrients are not co-limiting, and that P rather than N is limiting in this tropical forest. PMID:23593427

Enhanced accumulation and storage of mercury on subtropical evergreen forest floor: Implications on mercury budget in global forest ecosystems

NASA Astrophysics Data System (ADS)

Wang, Xun; Lin, Che-Jen; Lu, Zhiyun; Zhang, Hui; Zhang, Yiping; Feng, Xinbin

2016-08-01

Forest ecosystems play an important role in the global cycling of mercury (Hg). In this study, we characterized the Hg cycling at a remote evergreen broadleaf (EB) forest site in southwest China (Mount Ailao). The annual Hg input via litterfall is estimated to be 75.0 ± 24.2 µg m-2 yr-1 at Mount Ailao. Such a quantity is up to 1 order of magnitude greater than those observed at remote temperate/boreal (T/B) forest sites. Production of litter biomass is found to be the most influential factor causing the high Hg input to the EB forest. Given their large areal coverage, Hg deposition through litterfall in EB forests is appropriately 9 ± 5 Mg yr-1 in China and 1086 ± 775 Mg yr-1 globally. The observed wet Hg deposition at Mount Ailao is 4.9 ± 4.5 µg m-2 yr-1, falling in the lower range of those observed at 49 T/B forest sites in North America and Europe. Given the data, the Hg deposition flux through litterfall is approximately 15 times higher than the wet Hg deposition at Mount Ailao. Steady Hg accumulation in decomposing litter biomass and Hg uptake from the environment were observed during 25 months of litter decomposition. The size of the Hg pool in the organic horizon of EB forest floors is estimated to be up to 2-10 times the typical pool size in T/B forests. This study highlights the importance of EB forest ecosystems in global Hg cycling, which requires further assessment when more data become available in tropical forests.

Do the energy fluxes and surface conductance of boreal coniferous forests in Europe scale with leaf area?

PubMed

Launiainen, Samuli; Katul, Gabriel G; Kolari, Pasi; Lindroth, Anders; Lohila, Annalea; Aurela, Mika; Varlagin, Andrej; Grelle, Achim; Vesala, Timo

2016-12-01

Earth observing systems are now routinely used to infer leaf area index (LAI) given its significance in spatial aggregation of land surface fluxes. Whether LAI is an appropriate scaling parameter for daytime growing season energy budget, surface conductance (G s ), water- and light-use efficiency and surface-atmosphere coupling of European boreal coniferous forests was explored using eddy-covariance (EC) energy and CO 2 fluxes. The observed scaling relations were then explained using a biophysical multilayer soil-vegetation-atmosphere transfer model as well as by a bulk G s representation. The LAI variations significantly alter radiation regime, within-canopy microclimate, sink/source distributions of CO 2 , H 2 O and heat, and forest floor fluxes. The contribution of forest floor to ecosystem-scale energy exchange is shown to decrease asymptotically with increased LAI, as expected. Compared with other energy budget components, dry-canopy evapotranspiration (ET) was reasonably 'conservative' over the studied LAI range 0.5-7.0 m 2 m -2 . Both ET and G s experienced a minimum in the LAI range 1-2 m 2 m -2 caused by opposing nonproportional response of stomatally controlled transpiration and 'free' forest floor evaporation to changes in canopy density. The young forests had strongest coupling with the atmosphere while stomatal control of energy partitioning was strongest in relatively sparse (LAI ~2 m 2 m -2 ) pine stands growing on mineral soils. The data analysis and model results suggest that LAI may be an effective scaling parameter for net radiation and its partitioning but only in sparse stands (LAI <3 m 2 m -2 ). This finding emphasizes the significance of stand-replacing disturbances on the controls of surface energy exchange. In denser forests, any LAI dependency varies with physiological traits such as light-saturated water-use efficiency. The results suggest that incorporating species traits and site conditions are necessary when LAI is used in upscaling energy exchanges of boreal coniferous forests. © 2016 John Wiley & Sons Ltd.

Soil microbial community successional patterns during forest ecosystem restoration.

PubMed

Banning, Natasha C; Gleeson, Deirdre B; Grigg, Andrew H; Grant, Carl D; Andersen, Gary L; Brodie, Eoin L; Murphy, D V

2011-09-01

Soil microbial community characterization is increasingly being used to determine the responses of soils to stress and disturbances and to assess ecosystem sustainability. However, there is little experimental evidence to indicate that predictable patterns in microbial community structure or composition occur during secondary succession or ecosystem restoration. This study utilized a chronosequence of developing jarrah (Eucalyptus marginata) forest ecosystems, rehabilitated after bauxite mining (up to 18 years old), to examine changes in soil bacterial and fungal community structures (by automated ribosomal intergenic spacer analysis [ARISA]) and changes in specific soil bacterial phyla by 16S rRNA gene microarray analysis. This study demonstrated that mining in these ecosystems significantly altered soil bacterial and fungal community structures. The hypothesis that the soil microbial community structures would become more similar to those of the surrounding nonmined forest with rehabilitation age was broadly supported by shifts in the bacterial but not the fungal community. Microarray analysis enabled the identification of clear successional trends in the bacterial community at the phylum level and supported the finding of an increase in similarity to nonmined forest soil with rehabilitation age. Changes in soil microbial community structure were significantly related to the size of the microbial biomass as well as numerous edaphic variables (including pH and C, N, and P nutrient concentrations). These findings suggest that soil bacterial community dynamics follow a pattern in developing ecosystems that may be predictable and can be conceptualized as providing an integrated assessment of numerous edaphic variables.

Soil Microbial Community Successional Patterns during Forest Ecosystem Restoration ▿†

PubMed Central

Banning, Natasha C.; Gleeson, Deirdre B.; Grigg, Andrew H.; Grant, Carl D.; Andersen, Gary L.; Brodie, Eoin L.; Murphy, D. V.

2011-01-01

Soil microbial community characterization is increasingly being used to determine the responses of soils to stress and disturbances and to assess ecosystem sustainability. However, there is little experimental evidence to indicate that predictable patterns in microbial community structure or composition occur during secondary succession or ecosystem restoration. This study utilized a chronosequence of developing jarrah (Eucalyptus marginata) forest ecosystems, rehabilitated after bauxite mining (up to 18 years old), to examine changes in soil bacterial and fungal community structures (by automated ribosomal intergenic spacer analysis [ARISA]) and changes in specific soil bacterial phyla by 16S rRNA gene microarray analysis. This study demonstrated that mining in these ecosystems significantly altered soil bacterial and fungal community structures. The hypothesis that the soil microbial community structures would become more similar to those of the surrounding nonmined forest with rehabilitation age was broadly supported by shifts in the bacterial but not the fungal community. Microarray analysis enabled the identification of clear successional trends in the bacterial community at the phylum level and supported the finding of an increase in similarity to nonmined forest soil with rehabilitation age. Changes in soil microbial community structure were significantly related to the size of the microbial biomass as well as numerous edaphic variables (including pH and C, N, and P nutrient concentrations). These findings suggest that soil bacterial community dynamics follow a pattern in developing ecosystems that may be predictable and can be conceptualized as providing an integrated assessment of numerous edaphic variables. PMID:21724890

Changes in microbial community structure following herbicide (glyphosate) additions to forest soils

Treesearch

Alice W. Ratcliff; Matt D. Busse; Carol J. Shestak

2006-01-01

Glyphosate applied at the recommended field rate to a clay loam and a sandy loam forest soil resulted in few changes in microbial community structure. Total and culturable bacteria, fungal hyphal length, bacterial:fungal biomass, carbon utilization profiles (BIOLOG), and bacterial and fungal phospholipid fatty acids (PLFA) were unaffected 1, 3, 7, or 30 days...

Interactive effects of wildfire and permafrost on microbial communities and soil processes in an Alaskan black spruce forest.

Treesearch

Mark P. Waldrop; Jennifer W. Harden

2008-01-01

Boreal forests contain significant quantities of soil carbon that may be oxidized to CO2 given future increases in climate warming and wildfire behavior. At the ecosystem scale, decomposition and heterotrophic respiration are strongly controlled by temperature and moisture, but we questioned whether changes in microbial biomass, activity, or...

PLFA profiling of microbial community structure and seasonal shifts in soils of a Douglas-fir chronosequence

Treesearch

Jennifer Moore-Kucera; Richard P. Dick

2008-01-01

The impact and frequency of forest harvesting could significantly affect soil microbial community (SMC) structure and functioning. The ability of soil microorganisms to perform biogeochemical processes is critical for sustaining forest productivity and has a direct impact on decomposition dynamics and carbon storage potential. The Wind River Canopy Crane Research...

Short-term variability in labile soil phosphorus is positively related to soil moisture in a humid tropical forest in Puerto Rico

Treesearch

Tana E. Wood; Danielle Matthews; Karen Vandecar; Deborah Lawrence

2016-01-01

Primary productivity in tropical forests is often considered limited by phosphorus (P) availability. Microbial activity is a key regulator of available P through organic matter decomposition (supply) as well as microbial immobilization (depletion). Environmental conditions, such as soil moisture and temperature can fluctuate...

Winter climate change affects growing-season soil microbial biomass and activity in northern hardwood forests

Treesearch

Jorge Durán; Jennifer L. Morse; Peter M. Groffman; John L. Campbell; Lynn M. Christenson; Charles T. Driscoll; Timothy J. Fahey; Melany C. Fisk; Myron J. Mitchell; Pamela H. Templer

2014-01-01

Understanding the responses of terrestrial ecosystems to global change remains a major challenge of ecological research. We exploited a natural elevation gradient in a northern hardwood forest to determine how reductions in snow accumulation, expected with climate change, directly affect dynamics of soil winter frost, and indirectly soil microbial biomass and activity...

Statistical analysis of environmental monitoring data: does a worst case time for monitoring clean rooms exist?

PubMed

Cundell, A M; Bean, R; Massimore, L; Maier, C

1998-01-01

To determine the relationship between the sampling time of the environmental monitoring, i.e., viable counts, in aseptic filling areas and the microbial count and frequency of alerts for air, surface and personnel microbial monitoring, statistical analyses were conducted on 1) the frequency of alerts versus the time of day for routine environmental sampling conducted in calendar year 1994, and 2) environmental monitoring data collected at 30-minute intervals during routine aseptic filling operations over two separate days in four different clean rooms with multiple shifts and equipment set-ups at a parenteral manufacturing facility. Statistical analyses showed, except for one floor location that had significantly higher number of counts but no alert or action level samplings in the first two hours of operation, there was no relationship between the number of counts and the time of sampling. Further studies over a 30-day period at the floor location showed no relationship between time of sampling and microbial counts. The conclusion reached in the study was that there is no worst case time for environmental monitoring at that facility and that sampling any time during the aseptic filling operation will give a satisfactory measure of the microbial cleanliness in the clean room during the set-up and aseptic filling operation.

Increased Levels of Markers of Microbial Exposure in Homes with Indoor Storage of Organic Household Waste

PubMed Central

Wouters, Inge M.; Douwes, Jeroen; Doekes, Gert; Thorne, Peter S.; Brunekreef, Bert; Heederik, Dick J. J.

2000-01-01

As part of environmental management policies in Europe, separate collection of organic household waste and nonorganic household waste has become increasingly common. As waste is often stored indoors, this policy might increase microbial exposure in the home environment. In this study we evaluated the association between indoor storage of organic waste and levels of microbial agents in house dust. The levels of bacterial endotoxins, mold β(1→3)-glucans, and fungal extracullar polysaccharides (EPS) of Aspergillus and Penicillium species were determined in house dust extracts as markers of microbial exposure. House dust samples were collected in 99 homes in The Netherlands selected on the basis of whether separated organic waste was present in the house. In homes in which separated organic waste was stored indoors for 1 week or more the levels of endotoxin, EPS, and glucan were 3.2-, 7.6-, and 4.6-fold higher, respectively (all P < 0.05), on both living room and kitchen floors than the levels in homes in which only nonorganic residual waste was stored indoors. Increased levels of endotoxin and EPS were observed, 2.6- and 2.1-fold (P < 0.1), respectively, when separated organic waste was stored indoors for 1 week or less, whereas storage of nonseparated waste indoors had no effect on microbial agent levels (P > 0.2). The presence of textile floor covering was another major determinant of microbial levels (P < 0.05). Our results indicate that increased microbial contaminant levels in homes are associated with indoor storage of separated organic waste. These increased levels might increase the risk of bioaerosol-related respiratory symptoms in susceptible people. PMID:10653727

Summer survival of Phytophthora ramorum in California bay laurel leaves

Treesearch

Elizabeth J. Fichtner; David M. Rizzo; Shannon C. Lynch; Jennifer Davidson; Gerri Buckles; Jennifer Parker

2008-01-01

Sudden oak death manifests as non-lethal foliar lesions on bay laurel (Umbellularia californica), which support sporulation and survival of Phytophthora ramorum in forest ecosystems. Infected bay laurel leaves are more likely to abscise than uninfected leaves, resulting in an accumulation of inoculum at the forest floor. The pathogen survives the dry...

Prescribed fire and timber harvesting effects on soil carbon and nitrogen in a pine forest

USDA-ARS?s Scientific Manuscript database

Thinning and prescribed fire are common management tools used to eliminate thick fuel loads that could otherwise facilitate and encourage a more severe catastrophic wildfire. The objective of this study was to quantify the lasting effects of prescribed fire on forest floor and soil nutrients approxi...

Biodiversity and intentional management: a renaissance pathway.

Treesearch

Sally Duncan

1998-01-01

A project in western Washington tries to mimic natural disturbance to create forest structure similar to late-seral stages. A model was developed to identify pathways to achieve this structure with four indices: capacity to support vertebrate diversity, forest floor function, ecological productivity based on tree-using rodents, and production of deer and elk....

Compartmentalization of pathogens in fire-injured trees

Treesearch

Kevin T. Smith

2013-01-01

Wildland fire is an episodic process that greatly influences the composition, structure, and developmental sequence of forests. Most news reports of wildland fire involves blazes fueled by slash, standing dead stems, and snags that reach into tree crowns and burn deeply into the forest floor, causing extensive tree mortality and the eventual replacement of the standing...

Choosing suitable times for prescribed burning in southern New Jersey

Treesearch

S. Little; H. A. Somes; J. P. Allen

1952-01-01

Prescribed burning is useful in managing pine-oak forests in the Pine Region of southern New Jersey. It favors reproduction of pine by preparing suitable seed beds; it checks the development of hardwood reproduction; and it protects against wild fires by reducing the amount of fuel on the forest floor.

Calcium status of the forest floor in red spruce forests of the northeastern U.S. - past, present and future

Treesearch

Mark B. David; Gregory B. Lawrence; Walter C. Shortle; Scott W. Bailey

1996-01-01

Dieback and growth decline of red spruce (Picea rubens) in the eastern U.S. coincides with the period of acidic deposition, and has led to much speculation as to whether this decline is caused by decreased root-available Ca in the soil.

Restoring fire to mixed conifer forests in the Northern Cascades

Treesearch

T. J. Leuschen

1996-01-01

Many of the ponderosa pine (Pinus ponderosa) mixed conifer stands in the Methow Valley of north-central Washington have developed understories of Douglas-fir (Pseudotsuga rnenziesii) as a result of fire exclusion. Most of the forest floor has not yet become cluttered with dead woody fuel. Instead, the live biomass has increased and...

Annual Changes in Forst Floor Weights Under a Southeast Missouri Oak Stand

Treesearch

Robert M. Loomis

1975-01-01

Amount of organic matter on the forest floor under a typical southeast Missouri oak stand varies about 2.1 tons/acre from season of greatest to season to least accumulation. This also corresponds to the amount of annual litter fall. Maximum accumulation of 7.5 tons/acre occured in Novermber after leaf-fall. Summer decomposition is rapid; minimumof 5.4 tons/acre was...

A comparison of measured HONO uptake and release with calculated source strengths in a heterogeneous forest environment

NASA Astrophysics Data System (ADS)

Sörgel, Matthias; Trebs, Ivonne; Wu, Dianming; Held, Andreas

2015-04-01

Vertical mixing ratio profiles of nitrous acid (HONO) were measured in a clearing and on the forest floor in a rural forest environment (in the south-east of Germany) by applying a lift system to move the sampling unit of the LOng Path Absorption Photometer (LOPAP) up and down. For the forest floor, HONO was found to be predominantly deposited, whereas net deposition was dominating in the clearing only during nighttime and net emissions were observed during daytime. For selected days, net fluxes of HONO were calculated from the measured profiles using the aerodynamic gradient method. The emission fluxes were in the range of 0.02 to 0.07 nmol m-2 s-1, and, thus were in the lower range of previous observations. These fluxes were compared to the strengths of postulated HONO sources and to the amount of HONO needed to sustain photolysis in the boundary layer. Laboratory measurements of different soil samples from both sites revealed an upper limit for soil biogenic HONO emission fluxes of 0.025 nmol m-2 s-1. HONO formation by light induced NO2 conversion was calculated to be below 0.03 nmol m-2 s-1 for the investigated days, which is comparable to the potential soil fluxes. Due to light saturation at low irradiance, this reaction pathway was largely found to be independent of light intensity, i.e. it was only dependent on ambient NO2. We used three different approaches based on measured leaf nitrate loadings for calculating HONO formation from HNO3 photolysis. While the first two approaches based on empirical HONO formation rates yielded values in the same order of magnitude as the estimated fluxes, the third approach based on available kinetic data of the postulated pathway failed to produce noticeable amounts of HONO. Estimates based on reported cross sections of adsorbed HNO3 indicate that the lifetime of adsorbed HNO3 was only about 15 min, which would imply a substantial renoxification. Although the photolysis of HNO3 was significantly enhanced at the surface, the subsequent light induced conversion of the photolysis product NO2 did not produce considerable amounts of HONO. Consequently, this reaction might occur via an alternative mechanism. Therefore, the semi-volatile weak acid HONO can serve as an example for the complexity of exchange processes as multiple sources and sinks are coexisting, such as (photo-) chemical formation, microbial formation, adsorption/desorption and (stomatal-) uptake.

Winter climate change affects growing-season soil microbial biomass and activity in northern hardwood forests.

PubMed

Durán, Jorge; Morse, Jennifer L; Groffman, Peter M; Campbell, John L; Christenson, Lynn M; Driscoll, Charles T; Fahey, Timothy J; Fisk, Melany C; Mitchell, Myron J; Templer, Pamela H

2014-11-01

Understanding the responses of terrestrial ecosystems to global change remains a major challenge of ecological research. We exploited a natural elevation gradient in a northern hardwood forest to determine how reductions in snow accumulation, expected with climate change, directly affect dynamics of soil winter frost, and indirectly soil microbial biomass and activity during the growing season. Soils from lower elevation plots, which accumulated less snow and experienced more soil temperature variability during the winter (and likely more freeze/thaw events), had less extractable inorganic nitrogen (N), lower rates of microbial N production via potential net N mineralization and nitrification, and higher potential microbial respiration during the growing season. Potential nitrate production rates during the growing season were particularly sensitive to changes in winter snow pack accumulation and winter soil temperature variability, especially in spring. Effects of elevation and winter conditions on N transformation rates differed from those on potential microbial respiration, suggesting that N-related processes might respond differently to winter climate change in northern hardwood forests than C-related processes. © 2014 John Wiley & Sons Ltd.

Microbial populations and activities of mangrove, restinga and Atlantic forest soils from Cardoso Island, Brazil.

PubMed

Pupin, B; Nahas, E

2014-04-01

Mangroves provide a distinctive ecological environment that differentiates them from other ecosystems. This study deal to evaluate the frequency of microbial groups and the metabolic activities of bacteria and fungi isolated from mangrove, restinga and Atlantic forest soils. Soil samples were collected during the summer and winter at depths of 0-2, 2-5 and 5-10 cm. Except for fungi, the counts of the total, sporulating, Gram-negative, actinomycetes, nitrifying and denitrifying bacteria decreased significantly in the following order: Atlantic forest >mangrove > restinga. The counts of micro-organisms decreased by 11 and 21% from the surface to the 2-5 and 5-10 cm layers, but denitrifying bacteria increased by 44 and 166%, respectively. A larger growth of micro-organisms was verified in the summer compared with the winter, except for actinomycetes and fungi. The average frequency of bacteria isolated from mangrove, restinga and Atlantic forest soils was 95, 77 and 78%, and 93, 90 and 95% for fungi, respectively. Bacteria were amylolytic (33%), producers of acid phosphatase (79%) and solubilizers (18%) of inorganic phosphate. The proportions of fungi were 19, 90 and 27%. The mangrove soil studied had higher chemical characteristics than the Atlantic forest, but the high salinity may have restricted the growth of microbial populations. Estimates of the microbial counts and activities were important to elucidate the differences of mangrove ecosystem from restinga and Atlantic forest. © 2013 The Society for Applied Microbiology.

Effects of prescribed fire on conditions inside a Cuban parrot (Amazona Leucocephala) surrogate nesting cavity on Great Abaco, Bahamas

Treesearch

Joseph O' Brien; Caroline Stahala; Gina P. Mori; Mac Callaham; Chris M. Bergh

2006-01-01

Cuban Parrots (Amazona leucocephala) on the island of Great Abaco in the Bahamas forage and nest in native pine forests. The population is unique in that the birds nest in limestone solution holes on the forest floor. Bahamian pine forests are fire-dependent with a frequent surface fire regime. The effects of fire on the parrots, especially while nesting, are not well...

Emissions of forest floor and mineral soil carbon, nitrogen and mercury pools and relationships with fire severity for the Pagami Creek Fire in the Boreal Forest of northern Minnesota

Treesearch

Randall K. Kolka; Brian R. Sturtevant; Jessica R. Miesel; Aditya Singh; Peter T. Wolter; Shawn Fraver; Thomas M. DeSutter; Phil A. Townsend

2017-01-01

Forest fires cause large emissions of C (carbon), N (nitrogen) and Hg (mercury) to the atmosphere and thus have important implications for global warming (e.g. via CO2 and N2O emissions), anthropogenic fertilisation of natural ecosystems (e.g. via N deposition), and bioaccumulation of harmful metals in aquatic and...

Estimation of In-canopy Flux Distributions of Reactive Nitrogen and Sulfur within a Mixed Hardwood Forest in Southern Appalachia

NASA Astrophysics Data System (ADS)

Wu, Z.; Walker, J. T.; Chen, X.; Oishi, A. C.; Duman, T.

2017-12-01

Estimating the source/sink distribution and vertical fluxes of air pollutants within and above forested canopies is critical for understanding biological, physical, and chemical processes influencing the soil-vegetation-atmosphere exchange. The vertical source-sink profiles of reactive nitrogen and sulfur were examined using multiple inverse modeling methods in a mixed hardwood forest in the southern Appalachian Mountains where the ecosystem is highly sensitive to loads of pollutant from atmospheric depositions. Measurements of the vertical concentration profiles of ammonia (NH3), nitric acid (HNO3), sulfur dioxide (SO2), and ammonium (NH4+), nitrate (NO3-), and sulfate (SO42-) in PM2.5 were measured during five study periods between May 2015 and August 2016. The mean concentration of NH3 decreased with height in the upper canopy and increased below the understory toward the forest floor, indicating that the canopy was a sink for NH3 but the forest floor was a source. All other species exhibited patterns of monotonically decreasing concentration from above the canopy to the forest floor. Using the measured concentration profiles, we simulated the within-canopy flow fields and estimated the vertical source-sink flux profiles using three inverse approaches: a Eulerian high-order closure model (EUL), a Lagrangian localized near-field (LNF) model, and a new full Lagrangian stochastic model (LSM). The models were evaluated using the within- and above-canopy eddy covariance flux measurements of heat, CO2 and H2O. Differences between models were analyzed and the flux profiles were used to investigate the origin and fate of reactive nitrogen and sulfur compounds within the canopy. The knowledge gained in this study will benefit the development of soil-vegetation-atmosphere models capable of partitioning canopy-scale deposition of nitrogen and sulfur to specific ecosystem compartments.

Land-use and soil depth affect resource and microbial stoichiometry in a tropical mountain rainforest region of southern Ecuador.

PubMed

Tischer, Alexander; Potthast, Karin; Hamer, Ute

2014-05-01

Global change phenomena, such as forest disturbance and land-use change, significantly affect elemental balances as well as the structure and function of terrestrial ecosystems. However, the importance of shifts in soil nutrient stoichiometry for the regulation of belowground biota and soil food webs have not been intensively studied for tropical ecosystems. In the present account, we examine the effects of land-use change and soil depth on soil and microbial stoichiometry along a land-use sequence (natural forest, pastures of different ages, secondary succession) in the tropical mountain rainforest region of southern Ecuador. Furthermore, we analyzed (PLFA-method) whether shifts in the microbial community structure were related to alterations in soil and microbial stoichiometry. Soil and microbial stoichiometry were affected by both land-use change and soil depth. After forest disturbance, significant decreases of soil C:N:P ratios at the pastures were followed by increases during secondary succession. Microbial C:N ratios varied slightly in response to land-use change, whereas no fixed microbial C:P and N:P ratios were observed. Shifts in microbial community composition were associated with soil and microbial stoichiometry. Strong positive relationships between PLFA-markers 18:2n6,9c (saprotrophic fungi) and 20:4 (animals) and negative associations between 20:4 and microbial N:P point to land-use change affecting the structure of soil food webs. Significant deviations from global soil and microbial C:N:P ratios indicated a major force of land-use change to alter stoichiometric relationships and to structure biological systems. Our results support the idea that soil biotic communities are stoichiometrically flexible in order to adapt to alterations in resource stoichiometry.

Taxonomic and Functional Diversity of a Quercus pyrenaica Willd. Rhizospheric Microbiome in the Mediterranean Mountains

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

Cobo-Díaz, Jose F.; Fernández-González, Antonio J.; Villadas, Pablo J.

Altitude significantly affects vegetation growth and distribution, including the developmental stages of a forest. We used shotgun Illumina sequencing to analyze microbial community composition and functional potential in melojo-oak ( Quercus pyrenaica Willd.) rhizospheric soil for three different development stages along an altitudinal gradient: (a) a low altitude, non-optimal site for forest maintenance; (b) an intermediate altitude, optimal site for a forest; and (c) a high altitude, expansion site with isolated trees but without a real forest canopy. We observed that, at each altitude, the same microbial taxa appear both in the taxonomic analysis of the whole metagenome and inmore » the functional analysis of the methane, sulfur and nitrogen metabolisms. Although there were no major differences at the functional level, there were significant differences in the abundance of each taxon at the phylogenetic level between the rhizospheres of the forest (low and intermediate altitudes) and the expansion site. Proteobacteria and Actinobacteria were the most differentially abundant phyla in forest soils compared to the expansion site rhizosphere. Moreover, Verrucomicrobia, Bacteroidetes and Nitrospirae phyla were more highly represented in the non-forest rhizosphere. Our study suggests that rhizospheric microbial communities of the same tree species may be affected by development stage and forest canopy cover via changes in soil pH and the C/N ratio.« less

Taxonomic and Functional Diversity of a Quercus pyrenaica Willd. Rhizospheric Microbiome in the Mediterranean Mountains

DOE PAGES

Cobo-Díaz, Jose F.; Fernández-González, Antonio J.; Villadas, Pablo J.; ...

2017-10-12

Altitude significantly affects vegetation growth and distribution, including the developmental stages of a forest. We used shotgun Illumina sequencing to analyze microbial community composition and functional potential in melojo-oak ( Quercus pyrenaica Willd.) rhizospheric soil for three different development stages along an altitudinal gradient: (a) a low altitude, non-optimal site for forest maintenance; (b) an intermediate altitude, optimal site for a forest; and (c) a high altitude, expansion site with isolated trees but without a real forest canopy. We observed that, at each altitude, the same microbial taxa appear both in the taxonomic analysis of the whole metagenome and inmore » the functional analysis of the methane, sulfur and nitrogen metabolisms. Although there were no major differences at the functional level, there were significant differences in the abundance of each taxon at the phylogenetic level between the rhizospheres of the forest (low and intermediate altitudes) and the expansion site. Proteobacteria and Actinobacteria were the most differentially abundant phyla in forest soils compared to the expansion site rhizosphere. Moreover, Verrucomicrobia, Bacteroidetes and Nitrospirae phyla were more highly represented in the non-forest rhizosphere. Our study suggests that rhizospheric microbial communities of the same tree species may be affected by development stage and forest canopy cover via changes in soil pH and the C/N ratio.« less

Effects of vegetation type on microbial biomass carbon and nitrogen in subalpine mountain forest soils.

PubMed

Ravindran, Anita; Yang, Shang-Shyng

2015-08-01

Microbial biomass plays an important role in nutrient transformation and conservation of forest and grassland ecosystems. The objective of this study was to determine the microbial biomass among three vegetation types in subalpine mountain forest soils of Taiwan. Tatachia is a typical high-altitude subalpine temperate forest ecosystem in Taiwan with an elevation of 1800-3952 m and consists of three vegetation types: spruce, hemlock, and grassland. Three plots were selected in each vegetation type. Soil samples were collected from the organic layer, topsoil, and subsoil. Microbial biomass carbon (Cmic) was determined by the chloroform fumigation-extraction method, and microbial biomass nitrogen (Nmic) was determined from the total nitrogen (Ntot) released during fumigation-extraction. Bacteria, actinomycetes, fungi, cellulolytic microbes, phosphate-solubilizing microbes, and nitrogen-fixing microbes were also counted. The Cmic and Nmic were highest in the surface soil and declined with the soil depth. These were also highest in spruce soils, followed by in hemlock soils, and were lowest in grassland soils. Cmic and Nmic had the highest values in the spring season and the lowest values in the winter season. Cmic and Nmic had significantly positive correlations with total organic carbon (Corg) and Ntot. Contributions of Cmic and Nmic, respectively, to Corg and Ntot indicated that the microbial biomass was immobilized more in spruce and hemlock soils than in grassland soils. Microbial populations of the tested vegetation types decreased with increasing soil depth. Cmic and Nmic were high in the organic layer and decreased with the depth of layers. These values were higher for spruce and hemlock soils than for grassland soils. Positive correlations were observed between Cmic and Nmic and between Corg and Ntot. Copyright © 2014. Published by Elsevier B.V.

Above and belowground connections and species interactions: Controls over ecosystem fluxes

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

Trowbridge, Amy Marie; Phillips, Richard; Stoy, Paul Christopher

The ultimate goal of this work was to quantify soil and volatile organic compound fluxes as a function of tree species and associated mycorrhizal associations in an intact forest, but also to describe the physical and biological factors that control these emissions. The results of this research lay the foundation toward an improved mechanistic understanding of carbon pathways, fluxes, and ecosystem function, ultimately improving the representation of forest ecosystems in Earth System models. To this end, a multidisciplinary approach was necessary to fill a critical gap in our understanding of how soil and root processes may influence whole-ecosystem carbon-based volatilemore » fluxes in the face of a rapidly changing climate. We developed a series of novel sampling protocols and coupled a variety of advanced analytical techniques, resulting in findings relevant across disciplines. Furthermore, we leveraged existing infrastructure, research sites, and datasets to design a low-cost exploratory project that links belowground processes, soil volatile emissions, and total ecosystem carbon budgets. Measurements from soil collars installed across a species/mycorrhizal gradient at the DOE-supported Moran Monroe State Forest Ameriflux tower site suggest that leaf litter is the primary source of belowground and forest floor volatile emissions, but the strength of this source is significantly affected not only by leaf litter type, but the strength of the soil as a sink. Results suggest that the strength of the sink is influenced by tree species-specific associated microbial communities that change throughout the season as a function of temperature, soil moisture, leaf litter inputs, and phenology. The magnitude of the observed volatile fluxes from the forest floor is small relative to total aboveground ecosystem flux, but the contribution of these emissions to volatile-mediated ecological interactions and soil processes (e.g. nitrification) varies substantially across the growing season. This research lays the foundation to answer important questions regarding the impacts of seasonality and forest composition on belowground volatile source-sink dynamics in mediating nutrient cycling and biogeochemistry dynamics—critical components of overall ecosystem functioning. In collaboration with the Environmental Simulations Unit (EUS) at the Helmholtz Zentrum in Munich, Germany (headed by Prof. Dr. Joerg-Peter Schinitzler), we investigated carbon investment in above and belowground plant volatile compounds in response to environmental conditions and mycorrhizal associations. Using the sophisticated phytotron facility and on-line trace gas instruments, we conducted controlled laboratory experiments that showed that biotic stresses, such as herbivore feeding, can alter the magnitude of belowground volatile emissions as well as carbon allocation towards these volatiles. We saw no effect of mycorrhizae on any induced response, suggesting that microbial effects were unrelated to source-sink dynamics driving terpene emissions. Furthermore, the results suggest that even though enzyme activity responsible for root volatile synthesis is up-regulated following herbivory, the sink strength of the soil can significantly impact what is measured at the soil/atmosphere interface and thereby what enters the atmosphere. This is important as scientists may be underestimating the magnitude of belowground volatile emissions and their influence on belowground interactions due to limitations associated with current sampling techniques. These key findings are being integrated with results from a hydroxyl radical reactivity-VOC campaign and a late season litter removal experiment to offer a comprehensive mechanistic understanding of the sources and controls over soil volatile emissions, particularly during times of the year when vegetative aboveground emissions are low (leaf senescence). Ultimately, these coupled field and laboratory experiments offer insights into seasonal dynamics of volatile emissions and the mechanisms that control carbon allocation to these compounds with an eye towards improving carbon budgets, nutrient cycling, and terrestrial ecosystem models.« less

N-15 tracing helps explaining N leaching losses from contrasting forest ecosystems

NASA Astrophysics Data System (ADS)

Staelens, J.; Rütting, T.; Huygens, D.; Müller, C.; Verheyen, K.; Boeckx, P.

2009-04-01

Despite chronically enhanced nitrogen (N) deposition to forest ecosystems in Europe and NE America, considerable N retention by forests has been observed, reducing N leaching losses. Organic and mineral soil layers typically immobilize more N than the aboveground biomass, but it is unclear which factors determine N retention in forest ecoystems. However, this knowledge is crucial to assess the impact of changing anthropogenic N emissions on future N cycling and N loss of forests. For coniferous and deciduous forest stands at comparable sites, it is known that both N deposition onto the forest floor as well as N loss by leaching below the rooting zone are significantly higher in coniferous stands. In addition, the N loss in coniferous stands is often more enhanced than can be explained by the higher N input only. This suggests lower N retention by coniferous stands, and may be related to differences in litter and soil characteristics, microbial activity, and N uptake by plant roots. To test this hypothesis, we studied the effect of forest type on N retention using 15N tracing techniques: a field tracer experiment and a combination of in situ isotope pool dilution and a tracing model. The N dynamics were examined for two adjacent forest stands (pedunculate oak (Quercus robur L.) and Scots pine (Pinus sylvestris L.)) on a well-drained sandy soil and with a similar stand history, located in a region with high N deposition (Belgium). Input-output N budgets were established by quantifying atmospheric deposition and leaching below the rooting zone, and confirmed the above finding of higher N deposition and disproportionately higher N loss for the pine stand compared to the oak stand. First, the fate of inorganic N within the ecosystems was studied by spraying three pulses of dissolved 15N, either as ammonium or as nitrate, onto the forest floor in 12 plots of 25 m2. The organic and mineral soil layers, tree roots, soil water percolate, ferns, and tree foliage were sampled and analyzed for total N and 15N four times in the year after 15N application. Here we present results of the 15N recovery four months after the first application, and compare the recovery between the two forest stands and the two N treatments. Second, gross N transformation rates in the undisturbed mineral forest soils were determined via 15N pool dilution and advanced trace modelling. Using five spatial replicates per stand, three 15N treatments were applied in the field to 'virtual' soil cores (0-10 cm) that were disturbed only at sampling. Each treatment solution contained ammonium, nitrate, and nitrite, with one of the N forms labelled with 15N at 99% at. excess. Intact soil cores were sampled at six time intervals over a 12-day period, and analyzed for N and 15N content in different mineral and organic pools. The parameters of different simultaneously occurring process rates were optimized using a Markov Chain Monte Carlo algorithm. In both stands, heterotrophic nitrification of the organic soil pool was more important than autotrophic nitrification of ammonium. Significantly different process rates between the two forest stands were found for mineralization, heterotrophic and autotrophic nitrification, and ammonium and nitrate immobilization. Gross mineralization and ammonium immobilization rates were higher in the oak soil than in the pine soil. Gross nitrate production, in contrast, was faster in the pine soil, while nitrate immobilization was slower. These different soil nitrate dynamics likely contribute to the observed higher nitrate leaching loss in the pine than oak stand. In addition to the faster nitrate immobilization in the oak soil, our results strongly suggested the occurrence of a second N-conserving process under oak, i.e. dissimilatory nitrate reduction to ammonium (DNRA). This is unexpected for a temperate forest soil under enhanced N deposition, as this process has mainly been described for unpolluted soils.

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...

Microbial incorporation of nitrogen in stream detritus

Treesearch

Diane M. Sanzone; Jennifer L. Tank; Judy L. Meyer; Patrick J. Mulholland; Stuart E.G. Findlay

2001-01-01

We adapted the chloroform fumigation method to determine microbial nitrogen (N) and microbial incorporation of 15N on three common substrates [leaves, wood and fine benthic organic matter (FBOM)] in three forest streams. We compared microbial N and 15 content of samples collected during a 6-week15N-NH...

Soil carbon storage in plantation forests and pastures: land-use change implications

NASA Astrophysics Data System (ADS)

Scott, Neal A.; Tate, Kevin R.; Ford-Robertson, Justin; Giltrap, David J.; Tattersall Smith, C.

1999-04-01

Afforestation may lead to an accumulation of carbon (C) in vegetation, but little is known about changes in soil C storage with establishment of plantation forests. Plantation forest carbon budget models often omit mineral soil C changes from stand-level C budget calculations, while including forest floor C accumulation, or predict continuous soil C increases over several rotations. We used national soil C databases to quantify differences in soil C content between pasture and exotic pine forest plantations dominated by P. radiata (D. Don), and paired site studies to quantify changes in soil C with conversion of pasture to plantation forest in New Zealand. Overall, mineral soil C to 0.10 m was 20 40% lower under pine for all soil types (p<0.01) except soils with high clay activity (HCA), where there was no difference. Similar trends were observed in the 0.1 0.3 m layer. Moreover, mineral soil C to 0.1 m was 17 40% lower under pine than pasture in side-by-side comparisons. The only non-significant difference occurred at a site located on a HCA soil (p=0.08). When averaged across the site studies and the national databases, the difference in soil C between pasture and pine was about 16 t C ha1on non-HCA soils. This is similar to forest floor C averaged across our individual sites (about 20 t C ha1). The decrease in mineral soil C could result in about a 15% reduction in the average C sequestration potential (112 t C ha1) when pasture is converted to exotic plantation forest on non-HCA soils. The relative importance of this change in mineral soil C will likely vary depending on the productivity potential of a site and harvest impacts on the forest floor C pool. Our results emphasize that changes in soil C should be included in any calculations of C sequestration attributed to plantation forestry.

Decomposer food web in a deciduous forest shows high share of generalist microorganisms and importance of microbial biomass recycling.

PubMed

López-Mondéjar, Ruben; Brabcová, Vendula; Štursová, Martina; Davidová, Anna; Jansa, Jan; Cajthaml, Tomaš; Baldrian, Petr

2018-06-01

Forest soils represent important terrestrial carbon (C) pools where C is primarily fixed in the plant-derived biomass but it flows further through the biomass of fungi and bacteria before it is lost from the ecosystem as CO 2 or immobilized in recalcitrant organic matter. Microorganisms are the main drivers of C flow in forests and play critical roles in the C balance through the decomposition of dead biomass of different origins. Here, we track the path of C that enters forest soil by following respiration, microbial biomass production, and C accumulation by individual microbial taxa in soil microcosms upon the addition of 13 C-labeled biomass of plant, fungal, and bacterial origin. We demonstrate that both fungi and bacteria are involved in the assimilation and mineralization of C from the major complex sources existing in soil. Decomposer fungi are, however, better suited to utilize plant biomass compounds, whereas the ability to utilize fungal and bacterial biomass is more frequent among bacteria. Due to the ability of microorganisms to recycle microbial biomass, we suggest that the decomposer food web in forest soil displays a network structure with loops between and within individual pools. These results question the present paradigms describing food webs as hierarchical structures with unidirectional flow of C and assumptions about the dominance of fungi in the decomposition of complex organic matter.

Fuel accumulations in Piedmont loblolly pine plantations

Treesearch

Ernst V. Brender; W. Henry McNab; Shelton Williams

1976-01-01

Weight of minor vegetation under unthinned loblolly pine (Pinus taeda L.) plantations was closely related to stand age and basal area stocking. Weight of this vegetation peaked 3 years after clearcutting and planting, then diminished as the pine canopy became denser. Forest floor weight increased steadily through age 23, when it began to level off. Equilibrium forest...

Estimating soil seed bank characteristics in ponderosa pine forests using vegetation and forest-floor data

Treesearch

Scott R. Abella; Judith D. Springer

2008-01-01

Soil seed banks are important for vegetation management because they contain propagules of species that may be considered desirable or undesirable for site colonization after management and disturbance events. Knowledge of seed bank size and composition before planning management activities facilitates proactive management by providing early alerts of exotic species...

Maintenance and enhancement of long-term multiple socioeconomic benefits to meet the needs of societies

Treesearch

Nianfu Song; Stephen R. Shifley; Michael Bowker; Marla R. Emery; Francisco X. Aguilar; Kenneth E. Skog

2016-01-01

Forests are an important source of timber and nontimber products, recreation, ecological services, and employment in the Northern United States. Timber products are primarily used for building homes; manufacturing flooring, furniture, and cabinets; and making paper and paperboard. Residues from forest harvesting operations and wood processing are used for bioenergy,...

Distinctive fungal and bacterial communities are associated with mats formed by ectomycorrhizal fungi

Treesearch

Laurel A. Kluber; Jane E. Smith; David D. Myrold

2011-01-01

The distinct rhizomorphic mats formed by ectomycorrhizal Piloderma fungi are common features of the organic soil horizons of coniferous forests of the Pacific Northwest. These mats have been found to cover 25-40% of the forest floor in some Douglas-fir stands, and are associated with physical and biochemical properties that distinguish them from...

A throughfall collection method using mixed bed ion exchange resin columns

Treesearch

Mark E. Fenn; Mark A. Poth; Michael J. Arbaugh

2002-01-01

Measurement of ionic deposition in throughfall is a widely used method for measuring deposition inputs to the forest floor. Many studies have been published, providing a large database of throughfall deposition inputs to forests. However, throughfall collection and analysis is labor intensive and expensive because of the large number of replicate collectors needed and...

Characterizing movement of ground-dwelling arthropods with a novel mark-capture method using fluorescent powder

Treesearch

Kayla I. Perry; Kimberly F. Wallin; John W. Wenzel; Daniel A. Herms

2017-01-01

A major knowledge gap exists in understanding dispersal potential of ground-dwelling arthropods, especially in forest ecosystems. Movement of the ground-dwelling arthropod community was quantified using a novel markcapture technique in which three different colored fluorescent powders in two separate mixtures were applied to the floor of a deciduous forest in...

Fuel: Logs, sticks, needles, duff, and much more

Treesearch

Russell T. Graham; Theresa Benevidez Jain; Alan E. Harvey

2000-01-01

Fuels burned by either prescribed or wildfires are complex and important components of forested ecosystems. Fine fuels consisting of fallen limbs, twigs, and leaves of shrubs and trees are rich in nutrients. If these fuels are not immediately burned, nutrients can leach from these materials into the forest floor, especially if they overwinter. Larger fuels consisting...

Linking Soils and Down Woody Material Inventories for Cohesive Assessments of Ecosystem Carbon Pools

Treesearch

Katherine P. O' Neill; Christopher Woodall; Michael Amacher; Geoffrey Holden

2005-01-01

The Soils and Down Woody Materials (DWM) indicators collected by the Forest Inventory and Analysis program provide the only data available for nationally consistent monitoring of carbon storage in soils, the forest floor, and down woody debris. However, these indicators were developed and implemented separately, resulting in field methods and compilation procedures...

Survival, Growth, and Ecosystem Dynamics of Displaced Bromeliads in a Montane Tropical Forest.

Treesearch

Jennifer Pett-Ridge; Whendee L. Silver

2002-01-01

Epiphytes generally occupy arboreal perches, which are inherently unstable environments due to periodic windstorms, branch falls, and treefalls. During high wind events, arboreal bromeliads are often knocked from the canopy and deposited on the forest floor. In this study, we used a common epiphytic tank bromeliad, Guzmania berteroniana (R. & S.) Mez, to determine...

Lessons learned from fire use for restoring southwestern ponderosa pine ecosystems

Treesearch

Stephen S. Sackett; Sally M. Haase; Michael G. Harrington

1996-01-01

Since European settlement, the southwestern ponderosa pine ecosystem has experienced large scale alterations brought about by heavy grazing and timbering and a policy of attempted fire exclusion. These alterations are most evident as large increases in tree numbers and in forest floor organic matter. These changes have resulted in forest health problems, such...

Efficacy of buffer zones in disconnecting roads and streams in the coastal plain

Treesearch

J.M. III Grace; E. Davis

2010-01-01

Established forest BMPs rely heavily on the forest floor to disconnect upslope activities from stream systems. Optimizing the buffer length required to negate the storm runoff contribution of upslope activities has been a point of interest for soil scientist, hydrologist, and conservation professionals for the last century. Minimum buffer lengths have been recommended...

Forest productivity predicts invertebrate biomass and ovenbird (Seriurus Aurocapillus) reproduction in Appalachian landscapes

Treesearch

Steven W. Seagle; Brian R. Sturtevant

2005-01-01

Forest-floor detrital food webs are sustained by annual inputs of leaf fall. However, it is unknown whether this bottom-up effect extends to vertebrates feeding on the detrital food web. We hypothesized that reproductive success of Ovenbirds (Seiurus aurocapillus L.) is a function of acroinvertebrate biomass within the detrital food web, and that...

Linking Above- and Belowground Dynamics in Tropical Urban Forests

NASA Astrophysics Data System (ADS)

Atkinson, E. E.; Marin-Spiotta, E.

2013-12-01

Secondary forests that emerge after a long history of agriculture can have altered plant community composition and relative abundances of different species. These forests can look and behave differently compared to pre-agricultural forests due changes in primary productivity, resource allocation, and phenology, which can significantly affect processes such as carbon accumulation and nutrient availability. Our research explores how alternative successional trajectories following intensive agricultural use affect linkages among the establishment of novel plant communities, soil nutrient availability and turnover, and soil microbial community composition and function. We hypothesize that different plant species composition due to differing land use legacies and successional trajectories would drive changes in soil microbial community structure and function, affecting soil C and N chemistry and turnover. We conducted this research in the subtropical dry forest life zone of St. Croix, U.S. Virgin Islands where island-wide abandonment of sugarcane resulted in a mosaic of sites in different stages of forest succession. We identified replicate sites with the following post-sugarcane trajectories: 1) natural forest regeneration, 2) low intensity pasture use, followed by reforestation with timber plantation, which are no longer being managed, 3) high intensity pasture use and recent natural forest regeneration, and 4) high intensity pasture use and current active grazing. During 2011-2013, we sampled soils seasonally (0-10 cm) and measured tree species composition. The successional trajectories showed distinct tree species composition. The first two trajectories yielded 40-year old mixed-species secondary forest, dominated by the dry forest tree species Melicoccus bijugatas, Guapira fragrans, Maniklara zapota, and Sideroxylon foetidissimum. The tree species Melicoccus bijugatas primarily drove differences between the first two trajectories (natural forest regeneration vs. timber plantation and subsequent forest regeneration) while the N-fixing species Leucaena leucocephala drove differences between these forests and younger forests (10-year old), which only recently regenerated. The 40-year old mixed-species forests, regardless of successional trajectory, both had higher soil organic C and N (40 × 6 Mg C/ha and 3.8 × 6 Mg N/ha) compared to younger forests (32 × 2 Mg C/ha and 2.9 × 0.2 Mg N/ha) and active pastures. Active pastures had the lowest soil organic C and N (22 × 6 Mg C/ha and 2.1 × 0.5 Mg N/ha). We found that each successional trajectory showed distinct soil microbial community composition. In addition, the recently regenerated younger forests, dominated by N-fixing tree species, had higher microbial biomass and higher rates of N-cycling enzyme activity (N-acetyl glucosaminidase) when compared with the older, mixed-species forest. Our next step is to link microbial community structure and function with distinct forms of soil organic matter (SOM), and thus determine whether changes in function create distinct SOM stabilization pathways. To do this we will compare SOM chemistry and turnover for the different successional trajectories and analyze data from long-term leaf litter and root transplant experiments between the young and old secondary forests.

Impact of Long-Term Forest Enrichment Planting on the Biological Status of Soil in a Deforested Dipterocarp Forest in Perak, Malaysia

PubMed Central

Karam, D. S.; Arifin, A.; Radziah, O.; Shamshuddin, J.; Majid, N. M.; Hazandy, A. H.; Zahari, I.; Nor Halizah, A. H.; Rui, T. X.

2012-01-01

Deforestation leads to the deterioration of soil fertility which occurs rapidly under tropical climates. Forest rehabilitation is one of the approaches to restore soil fertility and increase the productivity of degraded areas. The objective of this study was to evaluate and compare soil biological properties under enrichment planting and secondary forests at Tapah Hill Forest Reserve, Perak after 42 years of planting. Both areas were excessively logged in the 1950s and left idle without any appropriate forest management until 1968 when rehabilitation program was initiated. Six subplots (20 m × 20 m) were established within each enrichment planting (F1) and secondary forest (F2) plots, after which soil was sampled at depths of 0–15 cm (topsoil) and 15–30 cm (subsoil). Results showed that total mean microbial enzymatic activity, as well as biomass C and N content, was significantly higher in F1 compared to F2. The results, despite sample variability, suggest that the rehabilitation program improves the soil biological activities where high rate of soil organic matter, organic C, N, suitable soil acidity range, and abundance of forest litter is believed to be the predisposing factor promoting higher population of microbial in F1 as compared to F2. In conclusion total microbial enzymatic activity, biomass C and biomass N evaluation were higher in enrichment planting plot compared to secondary forest. After 42 years of planting, rehabilitation or enrichment planting helps to restore the productivity of planted forest in terms of biological parameters. PMID:22606055

Seasonal variation in functional properties of microbial communities in beech forest soil

PubMed Central

Koranda, Marianne; Kaiser, Christina; Fuchslueger, Lucia; Kitzler, Barbara; Sessitsch, Angela; Zechmeister-Boltenstern, Sophie; Richter, Andreas

2013-01-01

Substrate quality and the availability of nutrients are major factors controlling microbial decomposition processes in soils. Seasonal alteration in resource availability, which is driven by plants via belowground C allocation, nutrient uptake and litter fall, also exerts effects on soil microbial community composition. Here we investigate if seasonal and experimentally induced changes in microbial community composition lead to alterations in functional properties of microbial communities and thus microbial processes. Beech forest soils characterized by three distinct microbial communities (winter and summer community, and summer community from a tree girdling plot, in which belowground carbon allocation was interrupted) were incubated with different 13C-labeled substrates with or without inorganic N supply and analyzed for substrate use and various microbial processes. Our results clearly demonstrate that the three investigated microbial communities differed in their functional response to addition of various substrates. The winter communities revealed a higher capacity for degradation of complex C substrates (cellulose, plant cell walls) than the summer communities, indicated by enhanced cellulase activities and reduced mineralization of soil organic matter. In contrast, utilization of labile C sources (glucose) was lower in winter than in summer, demonstrating that summer and winter community were adapted to the availability of different substrates. The saprotrophic community established in girdled plots exhibited a significantly higher utilization of complex C substrates than the more plant root associated community in control plots if additional nitrogen was provided. In this study we were able to demonstrate experimentally that variation in resource availability as well as seasonality in temperate forest soils cause a seasonal variation in functional properties of soil microorganisms, which is due to shifts in community structure and physiological adaptations of microbial communities to altered resource supply. PMID:23645937

Radiocaesium partitioning in Japanese cedar forests following the “early” phase of Fukushima fallout redistribution

PubMed Central

Coppin, Frederic; Hurtevent, Pierre; Loffredo, Nicolas; Simonucci, Caroline; Julien, Anthony; Gonze, Marc-Andre; Nanba, Kenji; Onda, Yuichi; Thiry, Yves

2016-01-01

Our study focused on radiocaesium (137Cs) partitioning in forests, three vegetation periods after the Fukushima Daiichi nuclear power plant accident. 137Cs distribution in forest components (organic and mineral soil layers as well as tree compartments: stem, bark, needles, branches and roots) was measured for two Japanese cedar stand ages (17 and 33 years old). The results showed that around 85% of the initial deposit was found in the forest floor and topsoil. For the youngest stand almost 70% of the deposit is present in the forest floor, whereas for the oldest stand 50% is present in the 0–3 cm mineral soil layer. For trees, old and perennial organs (including dead and living needles and branches, litter fall and outer bark) directly exposed to the fallout remained the most contaminated. The crown concentrated 61–69% of the total tree contamination. Surprisingly the dead organs concentrated 25 ± 9% (young cedars) to 36 ± 20% (mature cedar) of the trees’ residual activity, highlighting the importance of that specific compartment in the early post-accident phase for Japanese cedar forests. Although the stem (including bark) represents the highest biomass pool, it only concentrates 3.3% and 4.6% of the initial 137Cs deposit for mature and young cedars, respectively. PMID:27876870

Involvement of allelopathy in inhibition of understory growth in red pine forests.

PubMed

Kato-Noguchi, Hisashi; Kimura, Fukiko; Ohno, Osamu; Suenaga, Kiyotake

2017-11-01

Japanese red pine (Pinus densiflora Sieb. et Zucc.) forests are characterized by sparse understory vegetation although sunlight intensity on the forest floor is sufficient for undergrowth. The possible involvement of pine allelopathy in the establishment of the sparse understory vegetation was investigated. The soil of the red pine forest floor had growth inhibitory activity on six test plant species including Lolium multiflorum, which was observed at the edge of the forest but not in the forest. Two growth inhibitory substances were isolated from the soil and characterized to be 15-hydroxy-7-oxodehydroabietate and 7-oxodehydroabietic acid. Those compounds are probably formed by degradation process of resin acids. Resin acids are produced by pine and delivered into the soil under the pine trees through balsam and defoliation. Threshold concentrations of 15-hydroxy-7-oxodehydroabietate and 7-oxodehydroabietic acid for the growth inhibition of L. multiflorum were 30 and 10μM, respectively. The concentrations of 15-hydroxy-7-oxodehydroabietate and 7-oxodehydroabietic acid in the soil were 312 and 397μM, respectively, which are sufficient concentrations to cause the growth inhibition because of the threshold. These results suggest that those compounds are able to work as allelopathic agents and may prevent from the invasion of herbaceous plants into the forests by inhibiting their growth. Therefore, allelopathy of red pine may be involved in the formation of the sparse understory vegetation. Copyright © 2017 Elsevier GmbH. All rights reserved.

Fire, climate change, and forest resilience in interior Alaska

Treesearch

Jill F. Johnstone; F. Stuart Chapin; Teresa N. Hollingsworth; Michelle C. Mack; Vladimir Romanovsky; Merritt Turetsky

2010-01-01

In the boreal forests of interior Alaska, feedbacks that link forest soils, fire characteristics, and plant traits have supported stable cycles of forest succession for the past 6000 years. This high resilience of forest stands to fire disturbance is supported by two interrelated feedback cycles: (i) interactions among disturbance regime and plant-soil-microbial...

Microbial community structure and activity in a Colorado Rocky Mountain forest soil scarred by slash pile burning

Treesearch

Aida E. Jimenez Esquilin; Mary E. Stromberger; William J. Massman; John M. Frank; Wayne D. Shepperd

2007-01-01

Tree thinning and harvesting produces large amounts of slash material which are typically disposed of by burning, often resulting in severe soil heating. We measured soil chemical properties and microbial community structure and function over time to determine effects of slash pile burning in a ponderosa pine forest soil. Real time data were collected for soil...

Impacts of forest harvest on active carbon and microbial properties of a volcanic ash cap soil in northern Idaho

Treesearch

Deborah S. Page-Dumroese; Matt D. Busse; Steven T. Overby; Brian D. Gardner; Joanne M. Tirocke

2015-01-01

Soil quality assessments are essential for determining impacts on belowground microbial community structure and function. We evaluated the suitability of active carbon (C), a rapid field test, as an indicator of soil biological quality in five paired forest stands (clear cut harvested 40 years prior and unharvested) growing on volcanic ash-cap soils in northern Idaho....

Fine-scale variability of forest soil fungal communities in two contrasting habitat series in northern Idaho, USA identified with microbial metagenomics

Treesearch

Amy Ross-Davis; Jane E. Stewart; Matt Settles; John W. Hanna; John D. Shaw; Andrew T. Hudak; Deborah S. Page-Dumroese; Ned B. Klopfenstein

2016-01-01

Forests are home to some of the most complex microbial communities (Fierer et al. 2012) which drive biogeochemical cycles (Clemmensen et al. 2013; van der Heijden et al. 2008) and account for substantial terrestrial biomass (Nielsen et al. 2011). Fungi, through their ecological roles as decomposers, mutualists, or pathogens, are particularly important in...

H2O and CO2 fluxes at the floor of a boreal pine forest

NASA Astrophysics Data System (ADS)

Kulmala, Liisa; Launiainen, Samuli; Pumpanen, Jukka; Lankreijer, Harry; Lindroth, Anders; Hari, Pertti; Vesala, Timo

2008-04-01

We measured H2O and CO2 fluxes at a boreal forest floor using eddy covariance (EC) and chamber methods. Maximum evapotranspiration measured with EC ranged from 1.5 to 2.0mmol m-2 s-1 while chamber estimates depended substantially on the location and the vegetation inside the chamber. The daytime net CO2 exchange measured with EC (0-2μmol m-2 s-1) was of the same order as measured with the chambers. The nocturnal net CO2 exchange measured with the chambers ranged from 4 to 7μmol m-2 s-1 and with EC from ~4 to ~5μmol m-2 s-1 when turbulent mixing below the canopy was sufficient and the measurements were reliable. We studied gross photosynthesis by measuring the light response curves of the most common forest floor species and found the saturated rates of photosynthesis (Pmax) to range from 0.008 (mosses) to 0.184μmol g-1 s-1 (blueberry). The estimated gross photosynthesis at the study site based on average leaf masses and the light response curves of individual plant species was 2-3μmol m-2 s-1. At the same time, we measured a whole community with another chamber and found maximum gross photosynthesis rates from 4 to 7μmol m-2 s-1.

The microbiomes and metagenomes of forest biochars

NASA Astrophysics Data System (ADS)

Noyce, Genevieve L.; Winsborough, Carolyn; Fulthorpe, Roberta; Basiliko, Nathan

2016-05-01

Biochar particles have been hypothesized to provide unique microhabitats for a portion of the soil microbial community, but few studies have systematically compared biochar communities to bulk soil communities. Here, we used a combination of sequencing techniques to assess the taxonomic and functional characteristics of microbial communities in four-year-old biochar particles and in adjacent soils across three forest environments. Though effects varied between sites, the microbial community living in and around the biochar particles had significantly lower prokaryotic diversity and higher eukaryotic diversity than the surrounding soil. In particular, the biochar bacterial community had proportionally lower abundance of Acidobacteria, Planctomycetes, and β-Proteobacteria taxa, compared to the soil, while the eukaryotic biochar community had an 11% higher contribution of protists belonging to the Aveolata superphylum. Additionally, we were unable to detect a consistent biochar effect on the genetic functional potential of these microbial communities for the subset of the genetic data for which we were able to assign functions through MG-RAST. Overall, these results show that while biochar particles did select for a unique subset of the biota found in adjacent soils, effects on the microbial genetic functional potential appeared to be specific to contrasting forest soil environments.

The microbiomes and metagenomes of forest biochars

PubMed Central

Noyce, Genevieve L.; Winsborough, Carolyn; Fulthorpe, Roberta; Basiliko, Nathan

2016-01-01

Biochar particles have been hypothesized to provide unique microhabitats for a portion of the soil microbial community, but few studies have systematically compared biochar communities to bulk soil communities. Here, we used a combination of sequencing techniques to assess the taxonomic and functional characteristics of microbial communities in four-year-old biochar particles and in adjacent soils across three forest environments. Though effects varied between sites, the microbial community living in and around the biochar particles had significantly lower prokaryotic diversity and higher eukaryotic diversity than the surrounding soil. In particular, the biochar bacterial community had proportionally lower abundance of Acidobacteria, Planctomycetes, and β-Proteobacteria taxa, compared to the soil, while the eukaryotic biochar community had an 11% higher contribution of protists belonging to the Aveolata superphylum. Additionally, we were unable to detect a consistent biochar effect on the genetic functional potential of these microbial communities for the subset of the genetic data for which we were able to assign functions through MG-RAST. Overall, these results show that while biochar particles did select for a unique subset of the biota found in adjacent soils, effects on the microbial genetic functional potential appeared to be specific to contrasting forest soil environments. PMID:27212657

Influence of alternative silviculture on small mammals

USGS Publications Warehouse

Waldien, David L.; Hayes, John P.

2006-01-01

HIGHLIGHT: A variety of harvest methods promote diversity within forests while still generating income. For example, recent studies have shown that when dead wood is left on the forest floor during harvest, biodiversity increases. A new Cooperative Forest Ecosystem Research (CFER) program fact sheet summarizes how small mammals respond to dead wood in forests that are harvested with alternative methods. CFER is developing a series of fact sheets about responses to changes in young western Oregon forests. The fact sheets are designed to help resource managers balance management needs, including timber and wildlife. The USGS provides a primary source of financial support for CFER, a consortium of federal and state partners conducting research in support of the Northwest Forest Plan.

Effects of soil water repellency on microbial community structure and functions in Mediterranean pine forests

NASA Astrophysics Data System (ADS)

Lozano, Elena; Grayston, Sue J.; Mataix-Solera, Jorge; Arcenegui, Victoria; Jimenez-Pinilla, Patricia; Mataix-Beneyto, Jorge

2015-04-01

Soil water repellency (SWR) is a property commonly observed in forest areas showing wettable and water repellent patches with high spatial variability. SWR can greatly influence the hydrology and the ecology of forest soils. The capacity of soil microorganisms to degrade different organic compounds depends upon species composition, so this may affect changes in SWR on the microsite scale (such as the presence of soil water repellent patches; Mülleret al., 2010). In the Mediterranean forest context, SWR has been found to be related to microbial community composition. The accumulation of different hydrophobic compounds might be causing the shifts in microbial community structure (Lozano et al., 2014). In this study we investigated the effects of SWR persistence on soil microbial community structure and enzyme activity under Pinus halepensis forest in three different sites: Petrer, Gorga and Jávea (Alicante, E Spain). Soil samples were classified into three different water repellency classes (wettable, slight or strongly water repellent samples) depending on the SWR persistence. The soil microbial community was determined through phospholipid fatty acids (PLFAs). Enzyme activities chosen for this study were cellulase, β-glucosidase and N-acetyl-β-glucosaminide (NAG). The relationships between microbiological community structure and some soil properties such as pH, Glomalin Related Soil Protein, soil organic matter content and soil respiration were also studied. Redundancy analyses and decomposition of the variances were performed to clarify how microbial community composition and enzyme activities are affected by SWR and soil properties. The effect of SWR on microbial community composition differed between locations. This effect was clearer in the Petrer site. Enzyme activity varied considerably depending on SWR persistence. The highest activities were found in slightly SWR samples and the lowest mostly in the strongly water repellent ones. These preliminary results suggest a possible influence of SWR on microbial structure and its activity in soils. References: Lozano, E., García-Orenes, F., Bárcenas-Moreno, G., Jiménez-Pinilla, P., Mataix-Solera, J., Arcenegui, V., Morugán-Coronado, A., Mataix-Beneyto, J., 2014. Relationships between soil water repellency and microbial community composition under different plant species in a Mediterranean semiarid forest. J. Hydrol. Hydromech., 62, 101-107 Müller, K., Deurer, M., Newton, P.C.D., 2010. Is there a link between elevated atmospheric carbon dioxide concentration, soil water repellency and soil carbon mineralization? Agric. Ecosyst. Environ., 139, 98-109. Acknowledgements: to the "Ministerio de Economía and Competitividad" of Spanish Government for finance the POSTFIRE project (CGL2013- 47862-C2-1-R), Generalitat Valenciana for PhD grant, and Spanish Soil Science Society and FUEGORED for their support.

Observing and modeling links between soil moisture, microbes and CH4 fluxes from forest soils

NASA Astrophysics Data System (ADS)

Christiansen, Jesper; Levy-Booth, David; Barker, Jason; Prescott, Cindy; Grayston, Sue

2017-04-01

Soil moisture is a key driver of methane (CH4) fluxes in forest soils, both of the net uptake of atmospheric CH4 and emission from the soil. Climate and land use change will alter spatial patterns of soil moisture as well as temporal variability impacting the net CH4 exchange. The impact on the resultant net CH4 exchange however is linked to the underlying spatial and temporal distribution of the soil microbial communities involved in CH4 cycling as well as the response of the soil microbial community to environmental changes. Significant progress has been made to target specific CH4 consuming and producing soil organisms, which is invaluable in order to understand the microbial regulation of the CH4 cycle in forest soils. However, it is not clear as to which extent soil moisture shapes the structure, function and abundance of CH4 specific microorganisms and how this is linked to observed net CH4 exchange under contrasting soil moisture regimes. Here we report on the results from a research project aiming to understand how the CH4 net exchange is shaped by the interactive effects soil moisture and the spatial distribution CH4 consuming (methanotrophs) and producing (methanogens). We studied the growing season variations of in situ CH4 fluxes, microbial gene abundances of methanotrophs and methanogens, soil hydrology, and nutrient availability in three typical forest types across a soil moisture gradient in a temperate rainforest on the Canadian Pacific coast. Furthermore, we conducted laboratory experiments to determine whether the net CH4 exchange from hydrologically contrasting forest soils responded differently to changes in soil moisture. Lastly, we modelled the microbial mediation of net CH4 exchange along the soil moisture gradient using structural equation modeling. Our study shows that it is possible to link spatial patterns of in situ net exchange of CH4 to microbial abundance of CH4 consuming and producing organisms. We also show that the microbial community responds different to environmental change dependent on the soil moisture regime. These results are important to include in future modeling efforts to predict changes in soil-atmosphere exchange of CH4 under global change.

Urbanization Effects on the Vertical Distribution of Soil Microbial Communities and Soil C Storage across Edge-to-Interior Urban Forest Gradients

NASA Astrophysics Data System (ADS)

Rosier, C. L.; Van Stan, J. T., II; Trammell, T. L.

2017-12-01

Urbanization alters environmental conditions such as temperature, moisture, carbon (C) and nitrogen (N) deposition affecting critical soil processes (e.g., C storage). Urban soils experience elevated N deposition (e.g., transportation, industry) and decreased soil moisture via urban heat island that can subsequently alter soil microbial community structure and activity. However, there is a critical gap in understanding how increased temperatures and pollutant deposition influences soil microbial community structure and soil C/N cycling in urban forests. Furthermore, canopy structural differences between individual tree species is a potentially important mechanism facilitating the deposition of pollutants to the soil. The overarching goal of this study is to investigate the influence of urbanization and tree species structural differences on the bacterial and fungal community and C and N content of soils experiencing a gradient of urbanization pressures (i.e., forest edge to interior; 150-m). Soil cores (1-m depth) were collected near the stem (< 0.5 meter) of two tree species with contrasting canopy and bark structure (Fagus grandifolia, vs. Liriodendron tulipifera), and evaluated for soil microbial structure via metagenomic analysis and soil C/N content. We hypothesize that soil moisture constraints coupled with increases in recalcitrant C will decrease gram negative bacteria (i.e., dependent on labile C) while increasing saprophytic fungal community abundance (i.e., specialist consuming recalcitrant C) within both surface and subsurface soils experiencing the greatest urban pressure (i.e., forest edge). We further expect trees located on the edge of forest fragments will maintain greater surface soil (< 20 cm) C concentrations due to decreased soil moisture constraining microbial activity (e.g., slower decay), and increased capture of recalcitrant C stocks from industrial/vehicle emission sources (e.g., black C). Our initial results support our hypotheses that urbanization alters soil microbial community composition via reduced soil moisture and carbon storage potential via deposition gradients. Further analyses will answer important questions regarding how individual tree species alters urban soil C storage, N retention, and microbial dynamics.

Diversity of life in ocean floor basalt

NASA Astrophysics Data System (ADS)

Thorseth, I. H.; Torsvik, T.; Torsvik, V.; Daae, F. L.; Pedersen, R. B.

2001-12-01

Electron microscopy and biomolecular methods have been used to describe and identify microbial communities inhabiting the glassy margins of ocean floor basalts. The investigated samples were collected from a neovolcanic ridge and from older, sediment-covered lava flows in the rift valley of the Knipovich Ridge at a water depth around 3500 m and an ambient seawater temperature of -0.7°C. Successive stages from incipient microbial colonisation, to well-developed biofilms occur on fracture surfaces in the glassy margins. Observed microbial morphologies are various filamentous, coccoidal, oval, rod-shaped and stalked forms. Etch marks in the fresh glass, with form and size resembling the attached microbes, are common. Precipitation of alteration products around microbes has developed hollow subspherical and filamentous structures. These precipitates are often enriched in Fe and Mn. The presence of branching and twisted stalks that resemble those of the iron-oxidising Gallionella, indicate that reduced iron may be utilised in an energy metabolic process. Analysis of 16S-rRNA gene sequences from microbes present in the rock samples, show that the bacterial population inhabiting these samples cluster within the γ- and ɛ-Proteobacteria and the Cytophaga/Flexibacter/Bacteroides subdivision of the Bacteria, while the Archaea all belong to the Crenarchaeota kingdom. This microbial population appears to be characteristic for the rock and their closest relatives have previously been reported from cold marine waters in the Arctic and Antarctic, deep-sea sediments and hydrothermal environments.

Tropical forest soil microbes and climate warming: An Andean-Amazon gradient and `SWELTR'

NASA Astrophysics Data System (ADS)

Nottingham, A.; Turner, B. L.; Fierer, N.; Whitaker, J.; Ostle, N. J.; McNamara, N. P.; Bardgett, R.; Silman, M.; Bååth, E.; Salinas, N.; Meir, P.

2017-12-01

Climate warming predicted for the tropics in the coming century will result in average temperatures under which no closed canopy forest exists today. There is, therefore, great uncertainty associated with the direction and magnitude of feedbacks between tropical forests and our future climate - especially relating to the response of soil microbes and the third of global soil carbon contained in tropical forests. While warming experiments are yet to be performed in tropical forests, natural temperature gradients are powerful tools to investigate temperature effects on soil microbes. Here we draw on studies from a 3.5 km elevation gradient - and 20oC mean annual temperature gradient - in Peruvian tropical forest, to investigate how temperature affects the structure of microbial communities, microbial metabolism, enzymatic activity and soil organic matter cycling. With decreased elevation, soil microbial diversity increased and community composition shifted, from taxa associated with oligotrophic towards copiotrophic traits. A key role for temperature in shaping these patterns was demonstrated by a soil translocation experiment, where temperature-manipulation altered the relative abundance of specific taxa. Functional implications of these community composition shifts were indicated by changes in enzyme activities, the temperature sensitivity of bacterial and fungal growth rates, and the presence of temperature-adapted iso-enzymes at different elevations. Studies from a Peruvian elevation transect indicated that soil microbial communities are adapted to long-term (differences with elevation) and short-term (translocation responses) temperature changes. These findings indicate the potential for adaptation of soil microbes in tropical soils to future climate warming. However, in order to evaluate the sensitivity of these processes to climate warming in lowland forests, in situ experimentation is required. Finally, we describe SWELTR (Soil Warming Experiment in Lowland Tropical Rainforest), a new soil warming experiment being undertaken on Barro Colorado Island, Panama, designed to improve our understanding of biogeochemical feedbacks to climate warming in lowland tropical forests.

Microbial Biomass and Activity in Geomorphic Features in Forested and Urban Restored and Degraded Streams

EPA Science Inventory

Geomorphic spatial heterogeneity affects sediment denitrification, an anaerobic microbial process that results in the loss of nitrogen (N), and other anaerobic microbial processes such as methanogenesis in urban streams. We measured sediment denitrification potential (DEA), metha...

Monitoring of environmental conditions in taiga forests using ERS-1 SAR

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

Rignot, E.; Way, J.B.; McDonald, K.

1994-08-01

Synthetic-aperture radar images of forest site near Manley Hot Springs (64[degree]N, 151[degree]W), Alaska, were collected between August 1991 and December 1991, day and night, every 3 days, at C-band frequency ([lambda] = 5.7 cm), vertical receive and transmit polarization, by the European Space Agency First Remote Sensing Satellite, ERS-1. During the same period, air and soil temperatures and dielectric and gravimetric moisture properties of the forest canopy and forest floor were monitored in three forest stands dominated, respectively, by black spruce (Picea mariana), white spruce (Picea glauca), and balsam poplar (Populus balsamifera). The calibrated ERS-1 radar backscatter values, [sigma][degree], ofmore » the forest stands are shown to exhibit a pronounced temporal pattern, with little separability between tree species. The largest change in [sigma][degree], a 3-dB decrease almost independent of tree species, is observed in early winter when the soil and vegetation freeze. In the summer, temporal fluctuations in [sigma][degree] are about 1--2 dB in magnitude, depending on tree species. Diurnal variations in [sigma][degree] are as large as 2 dB during fall freeze-up, and less than 1 dB in summer and winter. These temporal variations in radar backscatter from the forest are interpreted using the MIMICS radar backscatter model and the in situ surface observations as due to changes in the dielectric properties of the forest floor and forest canopy induced by precipitation (summer), drought (fall), and freezing (fall-winter) events. In winter, [sigma][degree] increases across the entire landscape, probably because of volume scattering from large depth hoar ice crystals forming in the snow pack.« less

Fifteen-year patterns of soil carbon and nitrogen following biomass harvesting

Treesearch

Valerie J. Kurth; Anthony W. D' Amato; Brian J. Palik; John B. Bradford

2014-01-01

The substitution of forest-derived woody biofuels for fossil fuel energy has garnered increasing attention in recent years, but information regarding the mid- and long-term effects on soil productivity is limited. We investigated 15-yr temporal trends in forest floor and mineral soil (0-30 cm) C and N pools in response to organic matter removal treatments (OMR; stem-...

Physical properties of forest soils

Treesearch

Charles H. Perry; Michael C. Amacher

2007-01-01

Why Are Physical Properties of the Soil Important? The soil quality indicator, when combined with other data collected by the FIA program, can indicate the current rates of soil erosion, the extent and intensity of soil compaction, and some basic physical properties of the forest floor and the top 20 cm of soil. In this report, two particular physical properties of the...

Estimating ladder fuels: a new approach combining field photography with LiDAR

Treesearch

Heather Kramer; Brandon Collins; Frank Lake; Marek Jakubowski; Scott Stephens; Maggi Kelly

2016-01-01

Forests historically associated with frequent fire have changed dramatically due to fire suppression and past harvesting over the last century. The buildup of ladder fuels, which carry fire from the surface of the forest floor to tree crowns, is one of the critical changes, and it has contributed to uncharacteristically large and severe fires. The abundance of ladder...

Specific gravity relationships in plantation-grown red pine

Treesearch

Gregory Baker; James E. Shottafer

1968-01-01

Norway or red pine (Pinus resinosa Ait.) has been popular in Maine for forest planting because it will rapidly convert grass and weed cover to a forest floor and because it is relatively free from attack by insects and diseases. Since the first commercial thinnings consist of small-sized trees, the most logical market outlet is for pulpwood. Yield of...

Methods for measuring atmospheric nitrogen deposition inputs in arid and montane ecosystems of western North America

Treesearch

M.E. Fenn; J.O. Sickman; A. Bytnerowicz; D.W. Clow; N.P. Molotch; J.E. Pleim; G.S. Tonnesen; K.C. Weathers; P.E. Padgett; D.H. Campbell.

2009-01-01

Measuring atmospheric deposition in arid and snow-dominated regions presents unique challenges. Throughfall, the flux of nutrients transported in solution to the forest floor, is generally the most practical method of estimating below-canopy deposition, particularly when monitoring multiple forest sites or over multiple years. However, more studies are needed to relate...

Effects of tree leaf litter, deer fecal pellets, and soil properties on growth of an introduced earthworm (Lumbricus terrestris): Implications for invasion dynamics

Treesearch

Kassidy N. Yatso; Erik A. Lilleskov

2016-01-01

Invasive earthworm communities are expanding into previously earthworm-free forests of North America, producing profound ecosystem changes. Lumbricus terrestris is an invasive anecic earthworm that consumes a large portion of the detritus on the soil surface, eliminating forest floor organic horizons and reducing soil organic matter. Two mesocosm...

A comparison of the effects of different shelterwood harvest methods on the survival and growth of acorn-origin oak seedlings

Treesearch

Patrick H. Brose

2011-01-01

Timely development of newly germinated oak (Quercus spp.) seedlings into competitive-sized regeneration is an essential part of the oak regeneration process. The amount of sunlight reaching the forest floor partly governs this development, and foresters often use the shelterwood system to expose oak seedlings to varying degrees of insolation. To...

The technique of duff hygrometer calibration

Treesearch

T. Kachin; H. T. Gisborne

1937-01-01

The moisture content of the top layer of coniferous needles and twigs covering the forest floor is one of the factors of forest fire danger which must he determined accurately if fire danger in such timber types is to he measured. As this moisture content cannot he estimated accurately and as a difference of a few per cent of moisture, especially in the lower range,...

Beetle-killed stands in the South Carolina piedmont: from fuel hazards to regenerating oak forests

Treesearch

Aaron D. Stottlemyer; G. Geoff Wang; Thomas A. Waldrop

2012-01-01

Impacts of spring prescribed fire, mechanical mastication, and no-treatment (control) on fuels and natural hardwood tree regeneration were examined in beetle-killed stands in the South Carolina Piedmont. Mechanical mastication ground the down and standing dead trees and live vegetation into mulch and deposited it onto the forest floor. The masticated debris layer had...

Microbial activity discovered in previously ice-entombed Arctic ecosystems

NASA Astrophysics Data System (ADS)

Welker, J. M.; Fahnestock, J. T.; Henry, G. H. R.; 0'Dea, K. W.; Piper, R. E.

One of the more intriguing discoveries in the biogeochemical sciences in recent years is the tremendous capacity of microbial populations to occupy and flourish in extreme habitats [Rothschild and Mancinelli 2001]. Microbial populations survive and multiply under a diversity of harsh conditions, including the hot springs of Yellowstone National Park, Wyoming, and on the ocean floor around thermal vents. At the other extreme, active microbial communities occupy some of the coldest and driest habitats on Earth. For instance, a variety of bacterial and fungal species have been found in the Dry Valleys of Antarctica, and there is evidence that microbes are also present beneath the Antarctic Ice Sheet in Lake Vostok, a system that has not been exposed to the atmosphere for thousands of years.

Exploring the Woodland Floor

ERIC Educational Resources Information Center

Banner, Pat

1974-01-01

The article discusses the often ignored information that can be discovered by examining ground characteristics in woods and forests. Woodland cycles, the food chain, animal habitats, and nature's recycling are included. (KM)

Microbial biomass and bacterial functional diversity in forest soils: effects of organic matter removal, compaction, and vegetation control

Treesearch

Qingchao Li; H. Lee Allen; Arthur G. Wollum

2004-01-01

The effects of organic matter removal, soil compaction, and vegetation control on soil microbial biomass carbon, nitrogen, C-to-N ratio, and functional diversity were examined in a 6-year loblolly pine plantation on a Coastal Plain site in eastern North Carolina, USA. This experimental plantation was established as part of the US Forest Service's Long Term Soil...

Simulated nitrogen deposition causes a decline of intra- and extraradical abundance of arbuscular mycorrhizal fungi and changes in microbial community structure in northern hardwood forests

Treesearch

Linda T.A. van Diepen; Erik A. Lilleskov; Kurt S. Pregitzer; R. Michael Miller

2010-01-01

Increased nitrogen (N) deposition caused by human activities has altered ecosystem functioning and biodiversity. To understand the effects of altered N availability, we measured the abundance of arbuscular mycorrhizal fungi (AMF) and the microbial community in northern hardwood forests exposed to long-term (12 years) simulated N deposition (30 kg N ha-1...

Tropical forest carbon balance in a warmer world: a critical review spanning microbial- to ecosystem-scale processes

USGS Publications Warehouse

Wood, Tana E.; Cavaleri, Molly A.; Reed, Sasha C.

2012-01-01

Tropical forests play a major role in regulating global carbon (C) fluxes and stocks, and even small changes to C cycling in this productive biome could dramatically affect atmospheric carbon dioxide (CO2) concentrations. Temperature is expected to increase over all land surfaces in the future, yet we have a surprisingly poor understanding of how tropical forests will respond to this significant climatic change. Here we present a contemporary synthesis of the existing data and what they suggest about how tropical forests will respond to increasing temperatures. Our goals were to: (i) determine whether there is enough evidence to support the conclusion that increased temperature will affect tropical forest C balance; (ii) if there is sufficient evidence, determine what direction this effect will take; and, (iii) establish what steps should to be taken to resolve the uncertainties surrounding tropical forest responses to increasing temperatures. We approach these questions from a mass-balance perspective and therefore focus primarily on the effects of temperature on inputs and outputs of C, spanning microbial- to ecosystem-scale responses. We found that, while there is the strong potential for temperature to affect processes related to C cycling and storage in tropical forests, a notable lack of data combined with the physical, biological and chemical diversity of the forests themselves make it difficult to resolve this issue with certainty. We suggest a variety of experimental approaches that could help elucidate how tropical forests will respond to warming, including large-scale in situ manipulation experiments, longer term field experiments, the incorporation of a range of scales in the investigation of warming effects (both spatial and temporal), as well as the inclusion of a diversity of tropical forest sites. Finally, we highlight areas of tropical forest research where notably few data are available, including temperature effects on: nutrient cycling, heterotrophic versus autotrophic respiration, thermal acclimation versus substrate limitation of plant and microbial communities, below-ground C allocation, species composition (plant and microbial), and the hydraulic architecture of roots. Whether or not tropical forests will become a source or a sink of C in a warmer world remains highly uncertain. Given the importance of these ecosystems to the global C budget, resolving this uncertainty is a primary research priority.

Small-scale spatial variability of soil microbial community composition and functional diversity in a mixed forest

NASA Astrophysics Data System (ADS)

Wang, Qiufeng; Tian, Jing; Yu, Guirui

2014-05-01

Patterns in the spatial distribution of organisms provide important information about mechanisms that regulate the diversity and complexity of soil ecosystems. Therefore, information on spatial distribution of microbial community composition and functional diversity is urgently necessary. The spatial variability on a 26×36 m plot and vertical distribution (0-10 cm and 10-20 cm) of soil microbial community composition and functional diversity were studied in a natural broad-leaved Korean pine (Pinus koraiensis) mixed forest soil in Changbai Mountain. The phospholipid fatty acid (PLFA) pattern was used to characterize the soil microbial community composition and was compared with the community substrate utilization pattern using Biolog. Bacterial biomass dominated and showed higher variability than fungal biomass at all scales examined. The microbial biomass decreased with soil depths increased and showed less variability in lower 10-20 cm soil layer. The Shannon-Weaver index value for microbial functional diversity showed higher variability in upper 0-10 cm than lower 10-20 cm soil layer. Carbohydrates, carboxylic acids, polymers and amino acids are the main carbon sources possessing higher utilization efficiency or utilization intensity. At the same time, the four carbon source types contributed to the differentiation of soil microbial communities. This study suggests the higher diversity and complexity for this mix forest ecosystem. To determine the driving factors that affect this spatial variability of microorganism is the next step for our study.

Short- and long-term influence of stand density on soil microbial communities in ponderosa pine forests

Treesearch

Steven T. Overby

2009-01-01

Soil microbial communities process plant detritus and returns nutrients needed for plant growth. Increased knowledge of this intimate linkage between plant and soil microbial communities will provide a better understanding of ecosystem response to changing abiotic and biotic conditions. This dissertation consists of three studies to determine soil microbial community...

Microbial community variation and its relationship with nitrogen mineralization in historically altered forests

Treesearch

Jennifer M. Fraterrigo; Teri C. Balser; Monica g. Turner

2006-01-01

Past land use can impart soil legacies that have important implications for ecosystem function. Although these legacies have been linked with microbially mediated processes, little is known about the long-term influence of land use on soil microbial communities themselves. We examined whether historical land use affected soil microbial community composition (lipid...

The implications of microbial and substrate limitation for the fates of carbon in different organic soil horizon types of boreal forest ecosystems: a mechanistically based model analysis

USGS Publications Warehouse

He, Y.; Zhuang, Q.; Harden, Jennifer W.; McGuire, A. David; Fan, Z.; Liu, Y.; Wickland, Kimberly P.

2014-01-01

The large amount of soil carbon in boreal forest ecosystems has the potential to influence the climate system if released in large quantities in response to warming. Thus, there is a need to better understand and represent the environmental sensitivity of soil carbon decomposition. Most soil carbon decomposition models rely on empirical relationships omitting key biogeochemical mechanisms and their response to climate change is highly uncertain. In this study, we developed a multi-layer microbial explicit soil decomposition model framework for boreal forest ecosystems. A thorough sensitivity analysis was conducted to identify dominating biogeochemical processes and to highlight structural limitations. Our results indicate that substrate availability (limited by soil water diffusion and substrate quality) is likely to be a major constraint on soil decomposition in the fibrous horizon (40–60% of soil organic carbon (SOC) pool size variation), while energy limited microbial activity in the amorphous horizon exerts a predominant control on soil decomposition (>70% of SOC pool size variation). Elevated temperature alleviated the energy constraint of microbial activity most notably in amorphous soils, whereas moisture only exhibited a marginal effect on dissolved substrate supply and microbial activity. Our study highlights the different decomposition properties and underlying mechanisms of soil dynamics between fibrous and amorphous soil horizons. Soil decomposition models should consider explicitly representing different boreal soil horizons and soil–microbial interactions to better characterize biogeochemical processes in boreal forest ecosystems. A more comprehensive representation of critical biogeochemical mechanisms of soil moisture effects may be required to improve the performance of the soil model we analyzed in this study.

Relating belowground microbial composition to the taxonomic, phylogenetic, and functional trait distributions of trees in a tropical forest.

PubMed

Barberán, Albert; McGuire, Krista L; Wolf, Jeffrey A; Jones, F Andrew; Wright, Stuart Joseph; Turner, Benjamin L; Essene, Adam; Hubbell, Stephen P; Faircloth, Brant C; Fierer, Noah

2015-12-01

The complexities of the relationships between plant and soil microbial communities remain unresolved. We determined the associations between plant aboveground and belowground (root) distributions and the communities of soil fungi and bacteria found across a diverse tropical forest plot. Soil microbial community composition was correlated with the taxonomic and phylogenetic structure of the aboveground plant assemblages even after controlling for differences in soil characteristics, but these relationships were stronger for fungi than for bacteria. In contrast to expectations, the species composition of roots in our soil core samples was a poor predictor of microbial community composition perhaps due to the patchy, ephemeral, and highly overlapping nature of fine root distributions. Our ability to predict soil microbial composition was not improved by incorporating information on plant functional traits suggesting that the most commonly measured plant traits are not particularly useful for predicting the plot-level variability in belowground microbial communities. © 2015 John Wiley & Sons Ltd/CNRS.

How Clean Are Hotel Rooms? Part I: Visual Observations vs. Microbiological Contamination.

PubMed

Almanza, Barbara A; Kirsch, Katie; Kline, Sheryl Fried; Sirsat, Sujata; Stroia, Olivia; Choi, Jin Kyung; Neal, Jay

2015-01-01

Current evidence of hotel room cleanliness is based on observation rather than empirically based microbial assessment. The purpose of the study described here was to determine if observation provides an accurate indicator of cleanliness. Results demonstrated that visual assessment did not accurately predict microbial contamination. Although testing standards have not yet been established for hotel rooms and will be evaluated in Part II of the authors' study, potential microbial hazards included the sponge and mop (housekeeping cart), toilet, bathroom floor, bathroom sink, and light switch. Hotel managers should increase cleaning in key areas to reduce guest exposure to harmful bacteria.

Predicting the responsiveness of soil biodiversity to deforestation: a cross-biome study.

PubMed

Crowther, Thomas W; Maynard, Daniel S; Leff, Jonathan W; Oldfield, Emily E; McCulley, Rebecca L; Fierer, Noah; Bradford, Mark A

2014-09-01

The consequences of deforestation for aboveground biodiversity have been a scientific and political concern for decades. In contrast, despite being a dominant component of biodiversity that is essential to the functioning of ecosystems, the responses of belowground biodiversity to forest removal have received less attention. Single-site studies suggest that soil microbes can be highly responsive to forest removal, but responses are highly variable, with negligible effects in some regions. Using high throughput sequencing, we characterize the effects of deforestation on microbial communities across multiple biomes and explore what determines the vulnerability of microbial communities to this vegetative change. We reveal consistent directional trends in the microbial community response, yet the magnitude of this vegetation effect varied between sites, and was explained strongly by soil texture. In sandy sites, the difference in vegetation type caused shifts in a suite of edaphic characteristics, driving substantial differences in microbial community composition. In contrast, fine-textured soil buffered microbes against these effects and there were minimal differences between communities in forest and grassland soil. These microbial community changes were associated with distinct changes in the microbial catabolic profile, placing community changes in an ecosystem functioning context. The universal nature of these patterns allows us to predict where deforestation will have the strongest effects on soil biodiversity, and how these effects could be mitigated. © 2014 John Wiley & Sons Ltd.

Comparison of Forest Soil Carbon Dynamics at Five Sites Along a Latitudinal Gradient

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

Garten Jr, Charles T

2011-01-01

Carbon stocks, and C:N ratios, were measured in the forest floor, mineral soil, and two mineral soil fractions (particulate and mineral-associated organic matter, POM and MOM, respectively) at five forest sites, ranging from 60 to 100 years old, along a latitudinal gradient in the eastern United States. Sampling at four sites was replicated over two consecutive years. For many measurements (like forest floor carbon stocks, cumulative soil organic carbon stocks to 20 cm, and the fraction of whole soil carbon in POM), there was no significant difference between years at each site despite the use of somewhat different sampling methods.more » With one exception, forest floor and mineral soil carbon stocks increased from warm, southern, sites (with fine-textured soils) to northern, cool, sites (with more coarse-textured soils). The exception was a northern site, with less than 10% silt-clay content, that had a soil organic carbon stock similar to those measured at southern sites. Soil carbon at each site was partitioned into two pools (labile and stable) on the basis of carbon measured in the forest floor and POM and MOM fractions from the mineral soil. A two-compartment steady-state model, with randomly varying parameter values, was used in probabilistic calculations to estimate the turnover time of labile soil organic carbon (MRTU) and the annual transfer of labile carbon to stable carbon (k2) at each site in two different years. Based on empirical data, the turnover time of stable soil carbon (MRTS) was determined by mean annual temperature and increased from 30 to 100 years from south to north. Moving from south to north, MRTU increased from approximately 5 to 14 years. Consistent with prior studies, 13C enrichment factors ( ) from the Rayleigh equation, that describe the rate of change in 13C through the soil profile, were an indicator of soil carbon turnover times along the latitudinal gradient. Consistent with its role in stabilization of soil organic carbon, silt-clay content along the gradient was positively correlated (r = 0.91; P 0.001) with parameter k2. Mean annual temperature was indicated as the environmental factor most strongly associated with south to north differences in the storage and turnover of labile soil carbon. However, soil texture appeared to override the influence of temperature when there was too little silt-clay content to stabilize labile soil carbon and thereby protect it from decomposition. Irrespective of latitudinal differences in measured soil carbon stocks, each study site had a relatively high proportion of labile soil carbon (approximately 50% of whole soil carbon to a depth of 20 cm). Depending on unknown temperature sensitivities, large labile pools of forest soil carbon are potentially at risk of depletion by decomposition in a warming climate, and losses could be disproportionately higher from coarse textured forest soils.« less

Yosemite National Park

NASA Image and Video Library

2017-12-08

Naked summits alternate with forested lowlands in Yosemite Valley, part of California’s Yosemite National Park. During the Pleistocene Ice Age, glaciers sculpted the underlying rocks in this region, leaving behind canyons, waterfalls, rugged peaks, and granite domes. As the ice retreated, forests grew, but forests only extend as high as 2,900 meters (9,500 feet) above sea level. Above the tree line are rocky landscapes with sparse alpine vegetation. So from the sky, Yosemite Valley appears as a light-and-dark patchwork of forest, rock, and shadow. The Enhanced Thematic Mapper Plus on NASA’s Landsat 7 satellite captured this true-color image of part of Yosemite Valley on August 18, 2001. The valley runs roughly east-west, and tall granite peaks lining the valley’s southern side cast long shadows across the valley floor. On the valley’s northern side, steep slopes appear almost white. Along the valley floor, roadways form narrow, meandering lines of off-white, past parking lots, buildings, and meadows. On the north side of Yosemite Valley is El Capitan. Shooting straight up more than 915 meters (3,000 feet) above the valley floor, El Capitan is considered the largest granite monolith in the world. This granite monolith sits across the valley from Bridalveil Fall, one of the valley’s most prominent waterfalls. Read more: go.nasa.gov/2bzGo3d Credit: NASA/Landsat7 NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Evaporation components of a boreal forest: variations during the growing season

NASA Astrophysics Data System (ADS)

Grelle, A.; Lundberg, A.; Lindroth, A.; Morén, A.-S.; Cienciala, E.

1997-10-01

To improve the understanding of interactions between the boreal forest and the climate system as a key issue for global climate change, the water budget of a mixed pine and spruce forest in central Sweden was estimated by measurements of the water flux components and the total evaporation flux during the period 16 May-31 October 1995. Total evaporation was measured using eddy correlation and the components were obtained using measurements of precipitation, throughfall, tree transpiration, and forest floor evaporation. On a daily basis, tree transpiration was the dominant evaporation component during the vegetation period. However, it could be efficiently blocked by a wet canopy associated with large interception evaporation. The accumulated total evaporation was 399 mm, transpiration was 243 mm, forest floor evaporation was 56 mm and interception evaporation was 74 mm. The accumulated sum of interception, transpiration, and floor evaporation was 51 mm larger than the actual measured total evaporation. This difference was mainly attributed to the fact that transpiration was measured in a rather dense 50-year-old stand while total evaporation represented the average conditions of older, roughly 100-year-old stands. To compare eddy-correlation measurements with small-scale measurements of evaporation components, a source area analysis was made to select the flux data that give the best representation of the investigated stand. Especially under stable atmospheric conditions the requirements for surface homogeneity were very high and extreme care had to be taken to be aware of the flux source areas. Canopy water storage was determined by two methods: by the water balance of the canopy, which gave a result of 3.3 mm; and by the so-called minimum method based on plots of throughfall versus precipitation, which gave a much lower value of 1.5 mm. Seasonal interception evaporation constituted 30% of the precipitation.

Vertical distribution of soil extractable organic C and N contents and total C and N stocks in 78-year-old tree plantations in subtropical Australia.

PubMed

Zhou, Xiaoqi; Dong, Haibo; Lan, Zhongming; Bacon, Gary; Hao, Yanbin; Chen, Chengrong

2017-10-01

Few studies have focused on the effects of long-term forest plantations on the soil profile of carbon (C) and nitrogen (N) stocks. In this study, we selected 78-year-old tree plantations that included three coniferous tree species (i.e., slash pine, hoop pine and kauri pine) and a Eucalyptus species in subtropical Australia. We measured soil extractable organic C (EOC) and N (EON) contents and total C and N stocks under different tree species on the forest floor and along a soil profile to 100 cm depth. The results showed that Eucalyptus had significantly higher soil EOC contents (3.3 Mg ha -1 ) than the other tree species (EOC of 1.9-2.3 Mg ha -1 ) and had significantly higher EON (156 kg ha -1 ) contents than slash pine (107 kg ha -1 ). Eucalyptus had significantly higher soil C (58.9 Mg ha -1 ) and N (2.03 Mg ha -1 ) stocks than the other tree species (22.3-27.6 Mg C ha -1 and 0.71-1.23 Mg N ha -1 ) at 0-100 cm depth. There were no differences in soil C stocks at the 0-100 cm depth among the coniferous tree species. Forest floor C stocks had stronger effects on mineral soil total N stocks than fine root biomass, whereas fine root biomass exerted stronger effects on soil total C stocks at the 0-100 cm depth than forest floor C and N stocks. Our results addressed large differences in soil C and N stocks under different tree species, which can provide useful information for local forest management practices in this region.

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.

Rainfall and labile carbon availability control litter nitrogen dynamics in a tropical dry forest.

PubMed

Anaya, Carlos A; García-Oliva, Felipe; Jaramillo, Víctor J

2007-01-01

N cycling in tropical dry forests is driven by rainfall seasonality but the mechanisms involved are not well understood. We studied the seasonal variation in N dynamics and microbial biomass in the surface litter of a tropical dry forest ecosystem in Mexico over a 2-year period. Litter was collected at 4 different times of the year to determine changes in total, soluble, and microbial C and N concentrations. Additionally, litter from each sampling date was incubated under laboratory conditions to determine potential C mineralization rate, net N mineralization, net C and N microbial immobilization, and net nitrification. Litter C concentrations were highest in the early-dry season and lowest in the rainy season, while the seasonal changes in N concentrations varied between years. Litter P was higher in the rainy than in the early-dry season. Water-soluble organic C (WSOC) and water-soluble N concentrations were highest during the early- and late-dry seasons and represented up to 4.1 and 5.9% of the total C and N, respectively. NH (4) (+) and NO (3) (-) showed different seasonal and annual variations. They represented an average 23% of soluble N. Microbial C was generally higher in the dry than in the wet seasons, while microbial N was lowest in the late-dry and highest in the early-rainy seasons. Incubations showed that lowest potential C mineralization rates and C and N microbial immobilization occurred in rainy season litter, and were positively correlated to WSOC. Net nitrification was highest in rainy season litter. Our results showed that the seasonal pattern in N dynamics was influenced by rainfall seasonality and labile C availability, and not by microbial biomass. We propose a conceptual model to hypothesize how N dynamics in the litter layer of the Chamela tropical dry forest respond to the seasonal variation in rainfall.

Response of the soil microbial community and soil nutrient bioavailability to biomass harvesting and reserve tree retention in northern Minnesota aspen-dominated forests

Treesearch

Tera E. Lewandowski; Jodi A. Forrester; David J. Mladenoff; Anthony W. D' Amato; Brian J. Palik

2016-01-01

Intensive forest biomass harvesting, or the removal of harvesting slash (woody debris from tree branches and tops) for use as biofuel, has the potential to negatively affect the soil microbial community (SMC) due to loss of carbon and nutrient inputs from the slash, alteration of the soil microclimate, and increased nutrient leaching. These effects could result in...

Nitrogen Deposition Reduces Decomposition Rates Through Shifts in Microbial Community Composition and Function

NASA Astrophysics Data System (ADS)

Waldrop, M.; Zak, D.; Sinsabaugh, R.

2002-12-01

Atmospheric nitrogen (N) deposition may alter soil biological activity in northern hardwood forests by repressing phenol oxidase enzyme activity and altering microbial community composition, thereby slowing decomposition and increasing the export of phenolic compounds. We tested this hypothesis by adding 13C-labelled cellobiose, vanillin, and catechol to control and N fertilized soils (30 and 80 kg ha-1) collected from three forests; two dominated by Acer Saccharum and one dominated by Quercus Alba and Quercus Velutina. While N deposition increased total microbial respiration, it decreased soil oxidative enzyme activities, resulting in slower degradation rates of all compounds, and larger DOC pools. This effect was larger in the oak forest, where fungi dominate C-cycling processes. DNA and 13C-phospolipid analyses showed that N addition altered the fungal community and reduced the activity of fungal and bacterial populations in soil, potentially explaining reduced soil enzyme activities and incomplete decomposition.

Response of soricid populations to repeated fire and fuel reduction treatments in the southern Appalachain Mountains

Treesearch

Charlotte E Matthews; Christopher E Moorman; Cathryn H Greenberg

2009-01-01

Fuel hazards have increased in forests across the United States because offire exclusion during the 20th century. Treatments used to reduce fuel buildup Illay affect wildlife. such as shrews. living 011 the forest floor. especially when treatments are applied repeatedly. From mid-May to mid-August 2006 and 2007.  we used drift fences...

Cost and time study for constructing raised wood floor systems in the Gulf Coast Region of the United States

Treesearch

Marie Del Bianco; David B. McKeever; Lance Barta

2012-01-01

This report is the result of a co-operative effort between the USDA Forest Service, Forest Products Laboratory (FPL) Advanced Housing Research Center, the National Assocation of Home Builders (NAHB) Research Center, and builder members of the Metropolitan Mobile and Baldwin County Home Builders Associations. The study was undertaken to further knowledge that will...

Long-term (13 Years) decomposition rates of forest floor organic matter on paired coniferous and deciduous watersheds with contrasting temperature regimes

Treesearch

Robert G. Qualls

2016-01-01

Two sets of paired watersheds on north and South facing slopes were utilized to simulate the effects of temperature differences that are on the scale of those expected with near-term climatic warming on decomposition. Two watersheds were pine plantations (Pinus strobus L.) and two were mature deciduous forests established at similar elevation...

Estimation of Moisture Content of Forest Canopy and Floor from SAR Data Part II: Trunk-Ground Double-Bounce Case

NASA Technical Reports Server (NTRS)

Moghaddam, M.; Saatchi, S.

1996-01-01

Several scattering mechanisms contribute to the total radar backscatter cross section measured by the synthetic aperture radar. These are volume scattering, trunk-ground double-bounce scattering, branch-ground double-bounce scattering, and surface scattering. All of these mechanisms are directly related to the dielectric constant of forest components responsible for that mechanism and their moisture.

Response of Forest Floor Microarthropods to a Forest Regeneration Burn at Wine Spring Watershed (Southern Appalachians)

Treesearch

D.A Crossley; Randi A. Hansen; Karen L. Lamoncha

1997-01-01

We sampled microarthropods in litter and soil of the Wine Spring watershed on April 2,1995 before the watershed was burned, again on May. 9, 1995 immediately following burning> and two years later on June 9,1997.Pre-burn samples revealed a high abundance of mites (Arachnida: Atari) and collembolans. (Insecta: Collembola). Oriibatid (Atari: Oribatei) mites were...

Effects of land use change on soil carbon cycling in the conterminous United States from 1900 to 2050

Treesearch

Peter B. Woodbury; Linda S. Heath; James E. Smith

2007-01-01

We developed matrices representing historical area transitions between forest and other land uses. We projected future transitions on the basis of historical transitions and econometric model results. These matrices were used to drive a model of changes in soil and forest floor carbon stocks. Our model predicted net carbon emission from 1900 until 1982, then...

Wood decomposition following clearcutting at Coweeta Hydrologic Laboratory

Treesearch

Kim G. Mattson; Wayne T. Swank

2014-01-01

Most of the forest on Watershed (WS) 7 was cut and ledt on site to decompose. This Chapter describes the rate and manner of wood decomposition and also quantifies the fluxes from decaying wood to the forest floor on WS 7. In doing so, we make the case that wood and its process of decomposition contributes to ecosystem stability. We also review some of the history of...

Short-term effects of prescribed fire in grand fir-white pine-western hemlock slash fuels

Treesearch

Elizabeth D. Reinhardt; Russell T. Graham; Theresa B. Jain; Dennis G. Simmerman

1994-01-01

Experimental burns were conducted on 36 plots in mixed conifer logging slash in northern Idaho, under varying fuel loadings and moisture conditions. This paper reports the immediate effects of these burns on the forest floor, the woody fuel complex, and the plant community, and includes recommendations to managers for using prescribed fire in this forest type. Much of...

Development of floristic diversity in 10-year-old restoration forests on a bauxite mined site in Amazonia.

Treesearch

J. A. Parrotta; O. H. Knowles; J.M. Wunderle Jr.

1997-01-01

Patterns of plant and animal diversity were studied in a 10-year-old native species reforestation area at a bauxite-mined site at porto Trombetas in western Para State, Brazil. Understorey and overstorey floristic composition and structure, understorey light conditions, forest floor development and soil properties were evaluated in a total of 38 78.5-m2

Identifying calcium sources at an acid deposition-impacted spruce forest: A strontium isotope, alkaline earth element multi-tracer approach

USGS Publications Warehouse

Bullen, T.D.; Bailey, S.W.

2005-01-01

Depletion of calcium from forest soils has important implications for forest productivity and health. Ca is available to fine feeder roots from a number of soil organic and mineral sources, but identifying the primary source or changes of sources in response to environmental change is problematic. We used strontium isotope and alkaline earth element concentration ratios of trees and soils to discern the record of Ca sources for red spruce at a base-poor, acid deposition-impacted watershed. We measured 87Sr/86Sr and chemical compositions of cross-sectional stemwood cores of red spruce, other spruce tissues and sequential extracts of co-located soil samples. 87Sr/86Sr and Sr/Ba ratios together provide a tracer of alkaline earth element sources that distinguishes the plant-available fraction of the shallow organic soils from those of deeper organic and mineral soils. Ca/Sr ratios proved less diagnostic, due to within-tree processes that fractionate these elements from each other. Over the growth period from 1870 to 1960, 87Sr/86Sr and Sr/Ba ratios of stemwood samples became progressively more variable and on average trended toward values that considered together are characteristic of the uppermost forest floor. In detail the stemwood chemistry revealed an episode of simultaneous enhanced uptake of all alkaline earth elements during the growth period from 1930 to 1960, coincident with reported local and regional increases in atmospheric inputs of inorganic acidity. We attribute the temporal trends in stemwood chemistry to progressive shallowing of the effective depth of alkaline earth element uptake by fine roots over this growth period, due to preferential concentration of fine roots in the upper forest floor coupled with reduced nutrient uptake by roots in the lower organic and upper mineral soils in response to acid-induced aluminum toxicity. Although both increased atmospheric deposition and selective weathering of Ca-rich minerals such as apatite provide possible alternative explanations of aspects of the observed trends, the chemical buffering capacity of the forest floor-biomass pool limits their effectiveness as causal mechanisms. ?? Springer 2005.

Quantifying changes in total and pyrogenic carbon stocks across fire severity gradients using active wildfire incidents

NASA Astrophysics Data System (ADS)

Miesel, Jessica; Reiner, Alicia; Ewell, Carol; Maestrini, Bernardo; Dickinson, Matthew

2018-05-01

Positive feedbacks between wildfire emissions and climate are expected to increase in strength in the future; however, fires not only release carbon (C) from terrestrial to atmospheric pools, they also produce pyrogenic C (PyC) which contributes to longer-term C stability. Our objective was to quantify wildfire impacts on total C and PyC stocks in California mixed-conifer forest, and to investigate relationships between C and PyC stocks and changes across gradients of fire severity, using metrics derived from remote sensing and field observations. Our unique study accessed active wildfires to establish and measure plots within days before and after fire, prior to substantial erosion. We measured pre- and post-fire aboveground forest structure and woody fuels to calculate aboveground biomass, C and PyC, and collected forest floor and 0-5 cm mineral soil samples. Tree mortality increased with severity, but overstory C loss was minimal and limited primarily to foliage. Fire released 85% of understory and herbaceous C (comprising <1.0% of total ecosystem C). The greatest C losses occurred from downed wood and forest floor pools (19.3±5.1 Mg ha-1 and 25.9±3.2 Mg ha-1, respectively). Tree bark and downed wood contributed the greatest PyC gains (1.5±0.3 Mg ha-1 and 1.9±0.8 Mg ha-1, respectively), and PyC in tree bark showed non-significant positive trends with increasing severity. Overall PyC losses of 1.9±0.3 Mg ha-1 and 0.5±0.1 Mg ha-1 occurred from forest floor and 0-5 cm mineral soil, with no clear patterns across severity. Fire resulted in a net ecosystem PyC gain (0.96±0.98 Mg ha-1) across aboveground and belowground components of these forests, and there were no differences among severity levels. Carbon emissions represented only 21.6% of total forest C; however, extensive conversion of C from live to dead pools will contribute to large downed wood C pools susceptible to release in a subsequent fire, indicating that there may be a delayed relationship between fire severity and C emissions. This research advances understanding of forest C loss and stabilization as PyC in wildfires; however, poor relationships between C and PyC gains or losses and fire severity highlight the complexity of fire impacts on forest C.

Foliar litter decomposition in an alpine forest meta-ecosystem on the eastern Tibetan Plateau.

PubMed

Yue, Kai; Yang, Wanqin; Peng, Changhui; Peng, Yan; Zhang, Chuan; Huang, Chunping; Tan, Yu; Wu, Fuzhong

2016-10-01

Litter decomposition is a biological process fundamental to element cycling and a main nutrient source within forest meta-ecosystems, but few studies have looked into this process simultaneously in individual ecosystems, where environmental factors can vary substantially. A two-year field study conducted in an alpine forest meta-ecosystem with four litter species (i.e., willow: Salix paraplesia, azalea: Rhododendron lapponicum, cypress: Sabina saltuaria, and larch: Larix mastersiana) that varied widely in chemical traits showed that both litter species and ecosystem type (i.e., forest floor, stream and riparian zone) are important factors affecting litter decomposition, and their effects can be moderated by local-scale environmental factors such as temperature and nutrient availability. Litter decomposed fastest in the streams followed by the riparian zone and forest floor regardless of species. For a given litter species, both the k value and limit value varied significantly among ecosystems, indicating that the litter decomposition rate and extent (i.e., reaching a limit value) can be substantially affected by ecosystem type and the local-scale environmental factors. Apart from litter initial acid unhydrolyzable residue (AUR) concentration and its ratio to nitrogen concentration (i.e., AUR/N ratio), the initial nutrient concentrations of phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) were also important litter traits that affected decomposition depending on the ecosystem type. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparison of environmental and egg microbiology associated with conventional and free-range laying hen management.

PubMed

Jones, D R; Anderson, K E; Musgrove, M T

2011-09-01

Eggs from alternative production practices are a growing niche in the market. Meeting consumer requests for greater diversity in retail egg options has resulted in some unique challenges such as understanding the food safety implications of eggs from alternative production practices. A study was conducted to determine what, if any, differences exist between nest run conventional cage-produced eggs and free range-produced eggs. A sister flock of brown egg layers was maintained in conventional cage and free-range production with egg and environmental sampling every 6 wk from 20 to 79 wk of age. Aerobic, coliform, and yeast and mold populations were monitored. Environmental microbial levels were not always indicative of egg contamination levels. When significant differences (P < 0.05 and P < 0.0001, dependent on season) were observed among treatments for coliforms, shell contamination levels of free-range nest box eggs and free-range floor eggs were always greater than those of conventional cage eggs, which remained low throughout the study (0.42-0.02 log cfu/mL). Shell yeast and mold levels were significantly greater in free-range floor eggs than in free-range nest box eggs and conventional cage eggs throughout the entire study. Egg contents contamination levels were extremely low for all monitored populations and treatments. Season of the year played a role in both environmental and egg microbial levels. Winter had the lowest levels of all populations monitored for all treatments, except for aerobic free-range floor egg shell emulsions, which were increased (3.6 log cfu/mL). Understanding the differences in microbial populations present on conventional cage-produced and free range-produced eggs can lead to the development of effective cleaning procedures, enhancing food safety.

[Microbial community and its activities in canopy- and understory humus of two montane forest types in Ailao Mountains, Northwest China].

PubMed

Liu, Yong-jie; Liu, Wen-yao; Chen, Lin; Zhang, Han-bo; Wang, Gao-sheng

2010-09-01

Mid-montane moist evergreen broadleaved forest (MMF) and top-montane dwarf mossy forest (DMF) are the two major natural forest types in subtropical mountainous area of Ailao Mountains, Northwest China. In this paper, a comparative study was made on the microbial composition, quantity, biochemical activity, metabolic activity, and their seasonal dynamics in the canopy- and understory humus of the two forest types. The composition, quantity, and metabolic activity of the microbes in the canopy humus of dominant tree species in MMF and DMF were also analyzed. In the canopy humus of the two forest types, the amounts of fungi and actinomycetes, microbial biomass C and N, and intensities of nitrogen fixation and cellulose decomposition were significantly higher than those in understory humus. Meanwhile, the amount of cellulose-decomposing microbes (ACDM), cellulose decomposition intensity, microbial biomass C and N, and metabolic activity in the canopy humus of MMF were significantly higher than those of DMF. The amounts of bacteria, fungi, and aerobic nitrogen-fixing bacteria (ANFB) and the metabolic activity in the canopy humus of MMF and DMF were significantly higher in wet season than in dry season, while a contradictory trend was observed on the amount of actinomycetes. No significant difference was observed on the amount of ACDM between wet season and dry season. For the two forest types, the amounts of microbes and their biochemical activities in canopy humus had a larger seasonal variation range than those in understory humus. There was a significant difference in the amounts of the microbes in canopy humus among the dominant tree species in MMF and DMF, especially in wet season. The microbes in canopy humus played important roles in maintaining the biodiversity of epiphytes in the canopy, and in supplying the needed nutrients for the vigorous growth of the epiphytes.

[Dynamics of microbial biomass carbon and nitrogen during foliar litter decomposition under artificial forest gap in Pinus massoniana plantation.

PubMed

Zhang, Ming Jin; Chen, Liang Hua; Zhang, Jian; Yang, Wan Qin; Liu, Hua; Li, Xun; Zhang, Yan

2016-03-01

Nowadays large areas of plantations have caused serious ecological problems such as soil degradation and biodiversity decline. Artificial tending thinning and construction of mixed forest are frequently used ways when we manage plantations. To understand the effect of this operation mode on nutrient cycle of plantation ecosystem, we detected the dynamics of microbial bio-mass carbon and nitrogen during foliar litter decomposition of Pinus massoniana and Toona ciliate in seven types of gap in different sizes (G 1 : 100 m 2 , G 2 : 225 m 2 , G 3 : 400 m 2 , G 4 : 625 m 2 , G 5 : 900 m 2 , G 6 : 1225 m 2 , G 7 : 1600 m 2 ) of 42-year-old P. massoniana plantations in a hilly area of the upper Yang-tze River. The results showed that small and medium-sized forest gaps(G 1 -G 5 ) were more advantageous for the increment of microbial biomass carbon and nitrogen in the process of foliar litter decomposition. Along with the foliar litter decomposition during the experiment (360 d), microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) in P. massoniana foliar litter and MBN in T. ciliata foliar litter first increased and then decreased, and respectively reached the maxima 9.87, 0.22 and 0.80 g·kg -1 on the 180 th d. But the peak (44.40 g·kg -1 ) of MBC in T. ciliata foliar litter appeared on the 90 th d. Microbial biomass carbon and nitrogen in T. ciliate was significantly higher than that of P. massoniana during foliar litter decomposition. Microbial biomass carbon and nitrogen in foliar litter was not only significantly associated with average daily temperature and the water content of foliar litter, but also closely related to the change of the quality of litter. Therefore, in the thinning, forest gap size could be controlled in the range of from 100 to 900 m 2 to facilitate the increase of microbial biomass carbon and nitrogen in the process of foliar litter decomposition, accelerate the decomposition of foliar litter and improve soil fertility of plantations.

Long-term reactive nitrogen loading alters soil carbon and microbial community properties in a subalpine forest ecosystem

USGS Publications Warehouse

Boot, Claudia M.; Hall, Ed K.; Denef, Karolien; Baron, Jill S.

2016-01-01

Elevated nitrogen (N) deposition due to increased fossil fuel combustion and agricultural practices has altered global carbon (C) cycling. Additions of reactive N to N-limited environments are typically accompanied by increases in plant biomass. Soil C dynamics, however, have shown a range of different responses to the addition of reactive N that seem to be ecosystem dependent. We evaluated the effect of N amendments on biogeochemical characteristics and microbial responses of subalpine forest organic soils in order to develop a mechanistic understanding of how soils are affected by N amendments in subalpine ecosystems. We measured a suite of responses across three years (2011–2013) during two seasons (spring and fall). Following 17 years of N amendments, fertilized soils were more acidic (control mean 5.09, fertilized mean 4.68), and had lower %C (control mean 33.7% C, fertilized mean 29.8% C) and microbial biomass C by 22% relative to control plots. Shifts in biogeochemical properties in fertilized plots were associated with an altered microbial community driven by reduced arbuscular mycorrhizal (control mean 3.2 mol%, fertilized mean 2.5 mol%) and saprotrophic fungal groups (control mean 17.0 mol%, fertilized mean 15.2 mol%), as well as a decrease in N degrading microbial enzyme activity. Our results suggest that decreases in soil C in subalpine forests were in part driven by increased microbial degradation of soil organic matter and reduced inputs to soil organic matter in the form of microbial biomass.

Gene expression in the deep biosphere.

PubMed

Orsi, William D; Edgcomb, Virginia P; Christman, Glenn D; Biddle, Jennifer F

2013-07-11

Scientific ocean drilling has revealed a deep biosphere of widespread microbial life in sub-seafloor sediment. Microbial metabolism in the marine subsurface probably has an important role in global biogeochemical cycles, but deep biosphere activities are not well understood. Here we describe and analyse the first sub-seafloor metatranscriptomes from anaerobic Peru Margin sediment up to 159 metres below the sea floor, represented by over 1 billion complementary DNA (cDNA) sequence reads. Anaerobic metabolism of amino acids, carbohydrates and lipids seem to be the dominant metabolic processes, and profiles of dissimilatory sulfite reductase (dsr) transcripts are consistent with pore-water sulphate concentration profiles. Moreover, transcripts involved in cell division increase as a function of microbial cell concentration, indicating that increases in sub-seafloor microbial abundance are a function of cell division across all three domains of life. These data support calculations and models of sub-seafloor microbial metabolism and represent the first holistic picture of deep biosphere activities.

Phosphate addition enhanced soil inorganic nutrients to a large extent in three tropical forests.

PubMed

Zhu, Feifei; Lu, Xiankai; Liu, Lei; Mo, Jiangming

2015-01-21

Elevated nitrogen (N) deposition may constrain soil phosphorus (P) and base cation availability in tropical forests, for which limited evidence have yet been available. In this study, we reported responses of soil inorganic nutrients to full factorial N and P treatments in three tropical forests different in initial soil N status (N-saturated old-growth forest and two less-N-rich younger forests). Responses of microbial biomass, annual litterfall production and nutrient input were also monitored. Results showed that N treatments decreased soil inorganic nutrients (except N) in all three forests, but the underlying mechanisms varied depending on forests: through inhibition on litter decomposition in the old-growth forest and through Al(3+) replacement of Ca(2+) in the two younger forests. In contrast, besides great elevation in soil available P, P treatments induced 60%, 50%, 26% increases in sum of exchangeable (K(+)+Ca(2+)+Mg(2+)) in the old-growth and the two younger forests, respectively. These positive effects of P were closely related to P-stimulated microbial biomass and litter nutrient input, implying possible stimulation of nutrient return. Our results suggest that N deposition may result in decreases in soil inorganic nutrients (except N) and that P addition can enhance soil inorganic nutrients to support ecosystem processes in these tropical forests.

Phosphate addition enhanced soil inorganic nutrients to a large extent in three tropical forests

PubMed Central

Zhu, Feifei; Lu, Xiankai; Liu, Lei; Mo, Jiangming

2015-01-01

Elevated nitrogen (N) deposition may constrain soil phosphorus (P) and base cation availability in tropical forests, for which limited evidence have yet been available. In this study, we reported responses of soil inorganic nutrients to full factorial N and P treatments in three tropical forests different in initial soil N status (N-saturated old-growth forest and two less-N-rich younger forests). Responses of microbial biomass, annual litterfall production and nutrient input were also monitored. Results showed that N treatments decreased soil inorganic nutrients (except N) in all three forests, but the underlying mechanisms varied depending on forests: through inhibition on litter decomposition in the old-growth forest and through Al3+ replacement of Ca2+ in the two younger forests. In contrast, besides great elevation in soil available P, P treatments induced 60%, 50%, 26% increases in sum of exchangeable (K++Ca2++Mg2+) in the old-growth and the two younger forests, respectively. These positive effects of P were closely related to P-stimulated microbial biomass and litter nutrient input, implying possible stimulation of nutrient return. Our results suggest that N deposition may result in decreases in soil inorganic nutrients (except N) and that P addition can enhance soil inorganic nutrients to support ecosystem processes in these tropical forests. PMID:25605567

Soil microbiological properties and enzymatic activities of long-term post-fire recovery in dry and semiarid Aleppo pine (Pinus halepensis M.) forest stands

NASA Astrophysics Data System (ADS)

Hedo, J.; Lucas-Borja, M. E.; Wic, C.; Andrés-Abellán, M.; de Las Heras, J.

2015-02-01

Wildfires affecting forest ecosystems and post-fire silvicultural treatments may cause considerable changes in soil properties. The capacity of different microbial groups to recolonise soil after disturbances is crucial for proper soil functioning. The aim of this work was to investigate some microbial soil properties and enzyme activities in semiarid and dry Aleppo pine (Pinus halepensis M.) forest stands. Different plots affected by a wildfire event 17 years ago without or with post-fire silvicultural treatments 5 years after the fire event were selected. A mature Aleppo pine stand, unaffected by wildfire and not thinned was used as a control. Physicochemical soil properties (soil texture, pH, carbonates, organic matter, electrical conductivity, total N and P), soil enzymes (urease, phosphatase, β-glucosidase and dehydrogenase activities), soil respiration and soil microbial biomass carbon were analysed in the selected forests areas and plots. The main finding was that long time after this fire event produces no differences in the microbiological soil properties and enzyme activities of soil after comparing burned and thinned, burned and not thinned, and mature plots. Moreover, significant site variation was generally seen in soil enzyme activities and microbiological parameters. We conclude that total vegetation recovery normalises post-fire soil microbial parameters, and that wildfire and post-fire silvicultural treatments are not significant factors affecting soil properties after 17 years.

Spider foraging strategy affects trophic cascades under natural and drought conditions.

PubMed

Liu, Shengjie; Chen, Jin; Gan, Wenjin; Schaefer, Douglas; Gan, Jianmin; Yang, Xiaodong

2015-07-23

Spiders can cause trophic cascades affecting litter decomposition rates. However, it remains unclear how spiders with different foraging strategies influence faunal communities, or present cascading effects on decomposition. Furthermore, increased dry periods predicted in future climates will likely have important consequences for trophic interactions in detritus-based food webs. We investigated independent and interactive effects of spider predation and drought on litter decomposition in a tropical forest floor. We manipulated densities of dominant spiders with actively hunting or sit-and-wait foraging strategies in microcosms which mimicked the tropical-forest floor. We found a positive trophic cascade on litter decomposition was triggered by actively hunting spiders under ambient rainfall, but sit-and-wait spiders did not cause this. The drought treatment reversed the effect of actively hunting spiders on litter decomposition. Under drought conditions, we observed negative trophic cascade effects on litter decomposition in all three spider treatments. Thus, reduced rainfall can alter predator-induced indirect effects on lower trophic levels and ecosystem processes, and is an example of how such changes may alter trophic cascades in detritus-based webs of tropical forests.

Spider foraging strategy affects trophic cascades under natural and drought conditions

PubMed Central

Liu, Shengjie; Chen, Jin; Gan, Wenjin; Schaefer, Douglas; Gan, Jianmin; Yang, Xiaodong

2015-01-01

Spiders can cause trophic cascades affecting litter decomposition rates. However, it remains unclear how spiders with different foraging strategies influence faunal communities, or present cascading effects on decomposition. Furthermore, increased dry periods predicted in future climates will likely have important consequences for trophic interactions in detritus-based food webs. We investigated independent and interactive effects of spider predation and drought on litter decomposition in a tropical forest floor. We manipulated densities of dominant spiders with actively hunting or sit-and-wait foraging strategies in microcosms which mimicked the tropical-forest floor. We found a positive trophic cascade on litter decomposition was triggered by actively hunting spiders under ambient rainfall, but sit-and-wait spiders did not cause this. The drought treatment reversed the effect of actively hunting spiders on litter decomposition. Under drought conditions, we observed negative trophic cascade effects on litter decomposition in all three spider treatments. Thus, reduced rainfall can alter predator-induced indirect effects on lower trophic levels and ecosystem processes, and is an example of how such changes may alter trophic cascades in detritus-based webs of tropical forests. PMID:26202370

Impact of ecosystem management on microbial community level physiological profiles of postmining forest rehabilitation.

PubMed

Cookson, W R; O'Donnell, A J; Grant, C D; Grierson, P F; Murphy, D V

2008-02-01

We investigated the impacts of forest thinning, prescribed fire, and contour ripping on community level physiological profiles (CLPP) of the soil microbial population in postmining forest rehabilitation. We hypothesized that these management practices would affect CLPP via an influence on the quality and quantity of soil organic matter. The study site was an area of Jarrah (Eucalyptus marginata Donn ex Sm.) forest rehabilitation that had been mined for bauxite 12 years previously. Three replicate plots (20 x 20 m) were established in nontreated forest and in forest thinned from 3,000-8,000 stems ha(-1) to 600-800 stems ha(-1) in April (autumn) of 2003, followed either by a prescribed fire in September (spring) of 2003 or left nonburned. Soil samples were collected in August 2004 from two soil depths (0-5 cm and 5-10 cm) and from within mounds and furrows caused by postmining contour ripping. CLPP were not affected by prescribed fire, although the soil pH and organic carbon (C), total C and total nitrogen (N) contents were greater in burned compared with nonburned plots, and the coarse and fine litter mass lower. However, CLPP were affected by forest thinning, as were fine litter mass, soil C/N ratio, and soil pH, which were all higher in thinned than nonthinned plots. Furrow soil had greater coarse and fine litter mass, and inorganic phosphorous (P), organic P, organic C, total C, total N, ammonium, microbial biomass C contents, but lower soil pH and soil C/N ratio than mound soil. Soil pH, inorganic P, organic P, organic C, total C and N, ammonium, and microbial biomass C contents also decreased with depth, whereas soil C/N ratio increased. Differences in CLPP were largely (94%) associated with the relative utilization of gluconic, malic (greater in nonthinned than thinned soil and mound than furrow soil), L-tartaric, succinic, and uric acids (greater in thinned than nonthinned, mound than furrow, and 5-10 cm than 0-5 cm soil). The relative utilization of amino acids also tended to increase with increasing soil total C and organic C contents but decreased with increasing nitrate content, whereas the opposite was true for carboxylic acids. Only 45% of the variance in CLPP was explained using a multivariate multiple regression model, but soil C and N pools and litter mass were significant predictors of CLPP. Differences in soil textural components between treatments were also correlated with CLPP; likely causes of these differences are discussed. Our results suggest that 1 year after treatment, CLPP from this mined forest ecosystem are resilient to a spring prescribed fire but not forest thinning. We conclude that differences in CLPP are likely to result from complex interactions among soil properties that mediate substrate availability, microbial nutrient demand, and microbial community composition.

Soil Nitrogen-Cycling Responses to Conversion of Lowland Forests to Oil Palm and Rubber Plantations in Sumatra, Indonesia

PubMed Central

Tjoa, Aiyen; Veldkamp, Edzo

2015-01-01

Rapid deforestation in Sumatra, Indonesia is presently occurring due to the expansion of palm oil and rubber production, fueled by an increasing global demand. Our study aimed to assess changes in soil-N cycling rates with conversion of forest to oil palm (Elaeis guineensis) and rubber (Hevea brasiliensis) plantations. In Jambi Province, Sumatra, Indonesia, we selected two soil landscapes – loam and clay Acrisol soils – each with four land-use types: lowland forest and forest with regenerating rubber (hereafter, “jungle rubber”) as reference land uses, and rubber and oil palm as converted land uses. Gross soil-N cycling rates were measured using the 15N pool dilution technique with in-situ incubation of soil cores. In the loam Acrisol soil, where fertility was low, microbial biomass, gross N mineralization and NH4 + immobilization were also low and no significant changes were detected with land-use conversion. The clay Acrisol soil which had higher initial fertility based on the reference land uses (i.e. higher pH, organic C, total N, effective cation exchange capacity (ECEC) and base saturation) (P≤0.05–0.09) had larger microbial biomass and NH4 + transformation rates (P≤0.05) compared to the loam Acrisol soil. Conversion of forest and jungle rubber to rubber and oil palm in the clay Acrisol soil decreased soil fertility which, in turn, reduced microbial biomass and consequently decreased NH4 + transformation rates (P≤0.05–0.09). This was further attested by the correlation of gross N mineralization and microbial biomass N with ECEC, organic C, total N (R=0.51–0. 76; P≤0.05) and C:N ratio (R=-0.71 – -0.75, P≤0.05). Our findings suggest that the larger the initial soil fertility and N availability, the larger the reductions upon land-use conversion. Because soil N availability was dependent on microbial biomass, management practices in converted oil palm and rubber plantations should focus on enriching microbial biomass. PMID:26222690

Edge effects on foliar stable isotope values in a Madagascan tropical dry forest.

PubMed

Crowley, Brooke E; McGoogan, Keriann C; Lehman, Shawn M

2012-01-01

Edge effects represent an inevitable and important consequence of habitat loss and fragmentation. These effects include changes in microclimate, solar radiation, or temperature. Such abiotic effects can, in turn, impact biotic factors. They can have a substantial impact on species, communities, and ecosystems. Here we examine clinal variations in stable carbon and nitrogen isotope values for trees along an edge-interior gradient in the dry deciduous forest at Ankarafantsika National Park. We predicted that soil respiration and differences in solar irradiance would result in stratified δ¹³C values where leaves collected close to the forest floor would have lower δ¹³C values than those growing higher up in the canopy. We also anticipated that plants growing at the savannah-forest boundary would have higher δ¹³C and δ¹⁵N values than plants growing in the forest interior. As expected, we detected a small but significant canopy effect. Leaves growing below 2 m from the forest floor exhibit δ¹³C values that are, on average, 1.1‰ lower than those growing above this threshold. We did not, however, find any relationship between foliar δ¹³C and distance from the edge. Unpredictably, we detected a striking positive relationship between foliar δ¹⁵N values and increasing distance into the forest interior. Variability in physiology among species, anthropogenic influence, organic input, and rooting depth cannot adequately explain this trend. Instead, this unexpected relationship most likely reflects decreasing nutrient or water availability, or a shift in N-sources with increasing distance from the savannah. Unlike most forest communities, the trees at Ampijoroa are growing in nutrient-limited sands. In addition to being nutrient poor, these well-drained soils likely decrease the amount of soil water available to forest vegetation. Continued research on plant responses to edge effects will improve our understanding of the conservation biology of forest ecosystems in Madagascar.

Edge Effects on Foliar Stable Isotope Values in a Madagascan Tropical Dry Forest

PubMed Central

Crowley, Brooke E.; McGoogan, Keriann C.; Lehman, Shawn M.

2012-01-01

Edge effects represent an inevitable and important consequence of habitat loss and fragmentation. These effects include changes in microclimate, solar radiation, or temperature. Such abiotic effects can, in turn, impact biotic factors. They can have a substantial impact on species, communities, and ecosystems. Here we examine clinal variations in stable carbon and nitrogen isotope values for trees along an edge-interior gradient in the dry deciduous forest at Ankarafantsika National Park. We predicted that soil respiration and differences in solar irradiance would result in stratified δ13C values where leaves collected close to the forest floor would have lower δ13C values than those growing higher up in the canopy. We also anticipated that plants growing at the savannah-forest boundary would have higher δ13C and δ15N values than plants growing in the forest interior. As expected, we detected a small but significant canopy effect. Leaves growing below 2 m from the forest floor exhibit δ13C values that are, on average, 1.1‰ lower than those growing above this threshold. We did not, however, find any relationship between foliar δ13C and distance from the edge. Unpredictably, we detected a striking positive relationship between foliar δ15N values and increasing distance into the forest interior. Variability in physiology among species, anthropogenic influence, organic input, and rooting depth cannot adequately explain this trend. Instead, this unexpected relationship most likely reflects decreasing nutrient or water availability, or a shift in N-sources with increasing distance from the savannah. Unlike most forest communities, the trees at Ampijoroa are growing in nutrient-limited sands. In addition to being nutrient poor, these well-drained soils likely decrease the amount of soil water available to forest vegetation. Continued research on plant responses to edge effects will improve our understanding of the conservation biology of forest ecosystems in Madagascar. PMID:22973460

Carpeting in hospitals: an epidemiological evaluation.

PubMed Central

Anderson, R L; Mackel, D C; Stoler, B S; Mallison, G F

1982-01-01

Epidemiological and microbiological studies were conducted in a hospital room with carpet (CR) and in one with carpet (NCR). Microbiological profiles were determined with specimens obtained from patients admitted to these rooms. Patient records were reviewed to note infection status and other case identities. Eleven-millimeter cylindrical core samples of carpet were obtained, and swab template techniques were used on the bare floor for subsequent enumeration and identification of contaminating microorganisms. In each sampling period, higher microbial counts per square inch (1 in(2) = ca 6.452 cm(2)) were measured for the carpet than for the bare floor. Recovery rates of Enterobacter spp., Klebsiella pneumoniae, and Escherichia coli were higher from carpet samples than from bare floor samples. Typable organisms (such as E. coli, Pseudomonas aeruginosa, K. pneumoniae, and Staphylococcus aureus) obtained from patients were also more frequently recovered from the carpet than from the bare flooring. Patients who stayed in the CR were shown to be colonized with the same types of organisms as those initially recovered from the carpet. However, no statistically significant differences were found in patients in the CR versus NCR in colonization with all typable and nontypable organisms first found on the floor. Disease in patients was found not to be associated with organisms found as contaminants of the carpet or the bare floor. Air above carpeting contained more consistent concentrations of organisms than air above the bare flooring. PMID:7076814

Effects of post-hurricane fertilization and debris removal on earthworm abundance and biomass in subtropical forests in Puerto Rico

Treesearch

Grizelle Gonzalez; Y. Li; X. Zou

2007-01-01

Hurricanes are a common disturbance in the Caribbean, striking the island of Puerto Rico on average every 21 years. Hurricane Hugo (1989) distributed the canopy litter onto the forest floor changing the chemistry and quantity of litter inputs to the soil. In this study, we determined the effect of inorganic fertilization on earthworm abundance, biomass, and species...

The role of dead wood in maintaining arthropod diversity on the forest floor

Treesearch

James L. Hanula; Scott Horn; Dale D. Wade

2006-01-01

Dead wood is a major component of forests and contributes to overall diversity, primarily by supporting insects that feed directly on or in it. Further, a variety of organisms benefit by feeding on those insects. What is not well known is how or whether dead wood influences the composition of the arthropod community that is not solely dependent on it as a food...

Wildfire effects on a ponderosa pine ecosystem: An Arizona case study

Treesearch

R. E. Campbell; Jr. Baker; P. F. Ffolliott; F. R. Larson; C. C. Avery

1977-01-01

A wildfire of variable severity swept through 717 acres (290 ha) of ponderosa pine forest in north-central Arizona in May 1972. Where the fire was intense it killed 90% of the small trees and 50% of the sawtimber, burned 2.6 in (6.5 cm) of forest floor to the mineral soil, and induced a water-repellent layer in the sandier soils. The reduced infiltration rates, which...

Aluminum mobilization and calcium depletion in the forest floor of red spruce forests in the northeastern United States

Treesearch

Gregory B. Lawrence; Mark B. David; Walter C. Shortle

1996-01-01

Mechanisms of Ca depletion were investigated as part of a regional study of relations among acidic deposition, soil chemistry and red spruce decline. Comparison with results from studies in the Adirondack Mountains of New York and the White Mountains of New Hampshire indicates that current acid-extractable Ca concentrations in the Oa horizon are less than one-half the...