Defoliating Insect Mass Outbreak Affects Soil N Fluxes and Tree N Nutrition in Scots Pine Forests.

PubMed

Grüning, Maren M; Simon, Judy; Rennenberg, Heinz; L-M-Arnold, Anne

2017-01-01

Biotic stress by mass outbreaks of defoliating pest insects does not only affect tree performance by reducing its photosynthetic capacity, but also changes N cycling in the soil of forest ecosystems. However, how insect induced defoliation affects soil N fluxes and, in turn, tree N nutrition is not well-studied. In the present study, we quantified N input and output fluxes via dry matter input, throughfall, and soil leachates. Furthermore, we investigated the effects of mass insect herbivory on tree N acquisition (i.e., organic and inorganic 15 N net uptake capacity of fine roots) as well as N pools in fine roots and needles in a Scots pine ( Pinus sylvestris L.) forest over an entire vegetation period. Plots were either infested by the nun moth ( Lymantria monacha L.) or served as controls. Our results show an increased N input by insect feces, litter, and throughfall at the infested plots compared to controls, as well as increased leaching of nitrate. However, the additional N input into the soil did not increase, but reduce inorganic and organic net N uptake capacity of Scots pine roots. N pools in the fine roots and needles of infested trees showed an accumulation of total N, amino acid-N, protein-N, and structural N in the roots and the remaining needles as a compensatory response triggered by defoliation. Thus, although soil N availability was increased via surplus N input, trees did not respond with an increased N acquisition, but rather invested resources into defense by accumulation of amino acid-N and protein-N as a survival strategy.

Soil warming and CO2 enrichment induce biomass shifts in alpine tree line vegetation.

PubMed

Dawes, Melissa A; Philipson, Christopher D; Fonti, Patrick; Bebi, Peter; Hättenschwiler, Stephan; Hagedorn, Frank; Rixen, Christian

2015-05-01

Responses of alpine tree line ecosystems to increasing atmospheric CO2 concentrations and global warming are poorly understood. We used an experiment at the Swiss tree line to investigate changes in vegetation biomass after 9 years of free air CO2 enrichment (+200 ppm; 2001-2009) and 6 years of soil warming (+4 °C; 2007-2012). The study contained two key tree line species, Larix decidua and Pinus uncinata, both approximately 40 years old, growing in heath vegetation dominated by dwarf shrubs. In 2012, we harvested and measured biomass of all trees (including root systems), above-ground understorey vegetation and fine roots. Overall, soil warming had clearer effects on plant biomass than CO2 enrichment, and there were no interactive effects between treatments. Total plant biomass increased in warmed plots containing Pinus but not in those with Larix. This response was driven by changes in tree mass (+50%), which contributed an average of 84% (5.7 kg m(-2) ) of total plant mass. Pinus coarse root mass was especially enhanced by warming (+100%), yielding an increased root mass fraction. Elevated CO2 led to an increased relative growth rate of Larix stem basal area but no change in the final biomass of either tree species. Total understorey above-ground mass was not altered by soil warming or elevated CO2 . However, Vaccinium myrtillus mass increased with both treatments, graminoid mass declined with warming, and forb and nonvascular plant (moss and lichen) mass decreased with both treatments. Fine roots showed a substantial reduction under soil warming (-40% for all roots <2 mm in diameter at 0-20 cm soil depth) but no change with CO2 enrichment. Our findings suggest that enhanced overall productivity and shifts in biomass allocation will occur at the tree line, particularly with global warming. However, individual species and functional groups will respond differently to these environmental changes, with consequences for ecosystem structure and functioning. © 2014 John Wiley & Sons Ltd.

Defoliating Insect Mass Outbreak Affects Soil N Fluxes and Tree N Nutrition in Scots Pine Forests

PubMed Central

Grüning, Maren M.; Simon, Judy; Rennenberg, Heinz; l-M-Arnold, Anne

2017-01-01

Biotic stress by mass outbreaks of defoliating pest insects does not only affect tree performance by reducing its photosynthetic capacity, but also changes N cycling in the soil of forest ecosystems. However, how insect induced defoliation affects soil N fluxes and, in turn, tree N nutrition is not well-studied. In the present study, we quantified N input and output fluxes via dry matter input, throughfall, and soil leachates. Furthermore, we investigated the effects of mass insect herbivory on tree N acquisition (i.e., organic and inorganic 15N net uptake capacity of fine roots) as well as N pools in fine roots and needles in a Scots pine (Pinus sylvestris L.) forest over an entire vegetation period. Plots were either infested by the nun moth (Lymantria monacha L.) or served as controls. Our results show an increased N input by insect feces, litter, and throughfall at the infested plots compared to controls, as well as increased leaching of nitrate. However, the additional N input into the soil did not increase, but reduce inorganic and organic net N uptake capacity of Scots pine roots. N pools in the fine roots and needles of infested trees showed an accumulation of total N, amino acid-N, protein-N, and structural N in the roots and the remaining needles as a compensatory response triggered by defoliation. Thus, although soil N availability was increased via surplus N input, trees did not respond with an increased N acquisition, but rather invested resources into defense by accumulation of amino acid-N and protein-N as a survival strategy. PMID:28638396

Long-Term Simulated Atmospheric Nitrogen Deposition Alters ...

EPA Pesticide Factsheets

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

Hydraulic properties and fine root mass of Larix sibirica along forest edge-interior gradients

NASA Astrophysics Data System (ADS)

Chenlemuge, Tselmeg; Dulamsuren, Choimaa; Hertel, Dietrich; Schuldt, Bernhard; Leuschner, Christoph; Hauck, Markus

2015-02-01

At its southernmost distribution limit in Inner Asia, the boreal forest disintegrates into forest fragments on moist sites (e.g. north-facing slopes), which are embedded in grasslands. This landscape mosaic is characterized by a much higher forest edge-to-interior ratio than in closed boreal forests. Earlier work in the forest-steppe ecotone of Mongolia has shown that Larix sibirica trees at forest edges grow faster than in the forest interior, as the more xeric environment at the edge promotes self-thinning and edges are preferentially targeted by selective logging and livestock grazing. Lowered stand density reduces competition for water in these semi-arid forests, where productivity is usually limited by summer drought. We studied how branch and coarse root hydraulic architecture and xylem conductivity, fine root biomass and necromass, and fine root morphology of L. sibirica respond to sites differing in water availability. Studying forest edge-interior gradients in two regions of western Mongolia, we found a significant reduction of branch theoretical (Kp) and empirical conductivity (Ks) in the putatively more drought-affected forest interior in the Mongolian Altai (mean precipitation: 120 mm yr-1), while no branch xylem modification occurred in the moister Khangai Mountains (215 mm yr-1). Kp and Ks were several times larger in roots than in branches, but root hydraulics were not influenced by stand density or mean annual precipitation. Very low fine root biomass: necromass ratios at all sites, and in the forest interior in particular, suggest that L. sibirica seeks to maintain a relatively high root conductivity by producing large conduits, which results in high root mortality due to embolism during drought. Our results suggest that L. sibirica is adapted to the semi-arid climate at its southernmost distribution limit by considerable plasticity of the branch hydraulic system and a small but apparently dynamic fine root system.

Coupling fine-scale root and canopy structure using ground-based remote sensing

DOE PAGES

Hardiman, Brady S.; Gough, Christopher M.; Butnor, John R.; ...

2017-02-21

Ecosystem physical structure, defined by the quantity and spatial distribution of biomass, influences a range of ecosystem functions. Remote sensing tools permit the non-destructive characterization of canopy and root features, potentially providing opportunities to link above- and belowground structure at fine spatial resolution in functionally meaningful ways. To test this possibility, we employed ground-based portable canopy LiDAR (PCL) and ground penetrating radar (GPR) along co-located transects in forested sites spanning multiple stages of ecosystem development and, consequently, of structural complexity. We examined canopy and root structural data for coherence (i.e., correlation in the frequency of spatial variation) at multiple spatialmore » scales 10 m within each site using wavelet analysis. Forest sites varied substantially in vertical canopy and root structure, with leaf area index and root mass more becoming even vertically as forests aged. In all sites, above- and belowground structure, characterized as mean maximum canopy height and root mass, exhibited significant coherence at a scale of 3.5–4 m, and results suggest that the scale of coherence may increase with stand age. Our findings demonstrate that canopy and root structure are linked at characteristic spatial scales, which provides the basis to optimize scales of observation. Lastly, our study highlights the potential, and limitations, for fusing LiDAR and radar technologies to quantitatively couple above- and belowground ecosystem structure.« less

Coupling fine-scale root and canopy structure using ground-based remote sensing

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

Hardiman, Brady S.; Gough, Christopher M.; Butnor, John R.

Ecosystem physical structure, defined by the quantity and spatial distribution of biomass, influences a range of ecosystem functions. Remote sensing tools permit the non-destructive characterization of canopy and root features, potentially providing opportunities to link above- and belowground structure at fine spatial resolution in functionally meaningful ways. To test this possibility, we employed ground-based portable canopy LiDAR (PCL) and ground penetrating radar (GPR) along co-located transects in forested sites spanning multiple stages of ecosystem development and, consequently, of structural complexity. We examined canopy and root structural data for coherence (i.e., correlation in the frequency of spatial variation) at multiple spatialmore » scales 10 m within each site using wavelet analysis. Forest sites varied substantially in vertical canopy and root structure, with leaf area index and root mass more becoming even vertically as forests aged. In all sites, above- and belowground structure, characterized as mean maximum canopy height and root mass, exhibited significant coherence at a scale of 3.5–4 m, and results suggest that the scale of coherence may increase with stand age. Our findings demonstrate that canopy and root structure are linked at characteristic spatial scales, which provides the basis to optimize scales of observation. Lastly, our study highlights the potential, and limitations, for fusing LiDAR and radar technologies to quantitatively couple above- and belowground ecosystem structure.« less

Interactions Between Pinus taeda (loblolly) Fine Roots and Soil Fungi: Impacts of Elevated CO2, N Availability, and Spatial Distribution of Fungi on Fine Root Persistence and Turnover

NASA Astrophysics Data System (ADS)

Strand, A.; Beidler, K.; McGlinn, D.; Pritchard, S. G.

2016-12-01

Fine root turnover represents the most significant mode of flux from plants into soil C pools. Unfortunately fine root senescence and decomposition, processes critical in turnover, are particularly understudied. For example, little is known about either the factors that influence fine-root decomposition or the fate of compounds they contain during root death. Better understanding fine root senescence and decomposition should reduce uncertainty associated with global climate models; including re-uptake of materials in dying leaves into these models has already been shown to increase their accuracy. Over 4400 individual fine-roots and 4734 rhizomorphs were tracked from initiation until disintegration over 12 years using minirhizotrons at the Duke FACE site. Image-based approaches such as minirhizotrons cannot directly assess fine-root physiological status. To assess fine-root function directly, we are now conducting manipulative experiments in P. taeda in which fine-root senescence is induced through two treatments, steam- and direct hand-girdling. Physiological status is then assessed by examining gene-expression, root anatomy and chemical composition of manipulated roots. Changing [CO2] did not change persistence times for roots, but did impact rhizomorph persistence. Both roots and rhizomorphs showed interactions between effects of N and CO2 on persistence. Most interesting is the interaction between fine-roots and rhizomorphs: fine root persistence times are reduced in the presence of rhizomorphs, but this effect depends on the amount of N available. Finally, we found experimentally inducing senescence via steam girdling to be very effective relative to hand-girdling. These results provide evidence of the importance of priming on function of soil fungi and the role of N availability on fine-root turnover. The ability to stimulate fine-root senescence provides a powerful experimental tool to examine the fates of resources contained in fine-root pools as these roots turn over.

Redefining fine roots improves understanding of belowground contributions to terrestrial biosphere processes

DOE PAGES

McCormack, M. Luke; Dickie, Ian A.; Eissenstat, David M.; ...

2015-03-10

Fine roots acquire essential soil resources and mediate biogeochemical cycling in terrestrial ecosystems. Estimates of carbon and nutrient allocation to build and maintain these structures remain uncertain due to challenges in consistent measurement and interpretation of fine-root systems. We define fine roots as all roots less than or equal to 2 mm in diameter, yet it is now recognized that this approach fails to capture the diversity of form and function observed among fine-root orders. We demonstrate how order-based and functional classification frameworks improve our understanding of dynamic root processes in ecosystems dominated by perennial plants. In these frameworks, finemore » roots are separated into either individual root orders or functionally defined into a shorter-lived absorptive pool and a longer-lived transport fine root pool. Furthermore, using these frameworks, we estimate that fine-root production and turnover represent 22% of terrestrial net primary production globally a ca. 30% reduction from previous estimates assuming a single fine-root pool. In the future we hope to develop tools to rapidly differentiate functional fine-root classes, explicit incorporation of mycorrhizal fungi in fine-root studies, and wider adoption of a two-pool approach to model fine roots provide opportunities to better understand belowground processes in the terrestrial biosphere.« less

The decomposition of fine and coarse roots: their global patterns and controlling factors

PubMed Central

Zhang, Xinyue; Wang, Wei

2015-01-01

Fine root decomposition represents a large carbon (C) cost to plants, and serves as a potential soil C source, as well as a substantial proportion of net primary productivity. Coarse roots differ markedly from fine roots in morphology, nutrient concentrations, functions, and decomposition mechanisms. Still poorly understood is whether a consistent global pattern exists between the decomposition of fine (<2 mm root diameter) and coarse (≥2 mm) roots. A comprehensive terrestrial root decomposition dataset, including 530 observations from 71 sampling sites, was thus used to compare global patterns of decomposition of fine and coarse roots. Fine roots decomposed significantly faster than coarse roots in middle latitude areas, but their decomposition in low latitude regions was not significantly different from that of coarse roots. Coarse root decomposition showed more dependence on climate, especially mean annual temperature (MAT), than did fine roots. Initial litter lignin content was the most important predictor of fine root decomposition, while lignin to nitrogen ratios, MAT, and mean annual precipitation were the most important predictors of coarse root decomposition. Our study emphasizes the necessity of separating fine roots and coarse roots when predicting the response of belowground C release to future climate changes. PMID:25942391

[Distribution of fine root biomass of main planting tree species in Loess Plateau, China].

PubMed

Jian, Sheng-Qi; Zhao, Chuan-Yan; Fang, Shu-Min; Yu, Kai

2014-07-01

The distribution of fine roots of Pinus tabuliformis, Populus tomentosa, Prunus armeniaca, Robinia pseudoacacia, Hippophae rhamnoides, and Caragana korshinskii was investigated by using soil core method and the fine root was defined as root with diameter less than 2 mm. The soil moisture and soil properties were measured. The results showed that in the horizontal direction, the distribution of fine root biomass of P. tabuliformis presented a conic curve, and the fine root biomass of the other species expressed logarithm correlation. Radial roots developed, the fine root biomass were concentrated within the scope of the 2-3 times crown, indicating that trees extended their roots laterally to seek water farther from the tree. In the vertical direction, the fine root biomass decreased with the increasing soil depth. Fine root biomass had significant negative correlation with soil water content and bulk density, while significant positive correlation with organic matter and total N contents.

A model analysis of climate and CO2 controls on tree growth in a semi-arid woodland

NASA Astrophysics Data System (ADS)

Li, G.; Harrison, S. P.; Prentice, I. C.

2015-03-01

We used a light-use efficiency model of photosynthesis coupled with a dynamic carbon allocation and tree-growth model to simulate annual growth of the gymnosperm Callitris columellaris in the semi-arid Great Western Woodlands, Western Australia, over the past 100 years. Parameter values were derived from independent observations except for sapwood specific respiration rate, fine-root turnover time, fine-root specific respiration rate and the ratio of fine-root mass to foliage area, which were estimated by Bayesian optimization. The model reproduced the general pattern of interannual variability in radial growth (tree-ring width), including the response to the shift in precipitation regimes that occurred in the 1960s. Simulated and observed responses to climate were consistent. Both showed a significant positive response of tree-ring width to total photosynthetically active radiation received and to the ratio of modeled actual to equilibrium evapotranspiration, and a significant negative response to vapour pressure deficit. However, the simulations showed an enhancement of radial growth in response to increasing atmospheric CO2 concentration (ppm) ([CO2]) during recent decades that is not present in the observations. The discrepancy disappeared when the model was recalibrated on successive 30-year windows. Then the ratio of fine-root mass to foliage area increases by 14% (from 0.127 to 0.144 kg C m-2) as [CO2] increased while the other three estimated parameters remained constant. The absence of a signal of increasing [CO2] has been noted in many tree-ring records, despite the enhancement of photosynthetic rates and water-use efficiency resulting from increasing [CO2]. Our simulations suggest that this behaviour could be explained as a consequence of a shift towards below-ground carbon allocation.

Incorporation of 13C labeled Pinus ponderosa needle and fine root litter into soil organic matter measured by Py-GC/MS-C-IRMS

NASA Astrophysics Data System (ADS)

Mambelli, S.; Gleixner, G.; Dawson, T. E.; Bird, J. A.; Torn, M. S.

2006-12-01

Developing effective strategies for enhancing C storage in soils requires understanding the influence of plant C quality. In turn, plant C quality impacts the decay continuum between plant residue and humified, stable SOM. This remains one of the least understood aspects of soil biogeochemistry. We investigated the initial phase of incorporation of 13C labeled Pinus ponderosa needle and fine root litter into SOM. The two litter types were placed in separate microcosms in the A horizon in a temperate conifer soil. Curie-point pyrolysis-gas chromatography coupled with on-line mass spectrometry and isotope ratio mass spectrometry (Py-GC/MS-C- IRMS) were used to determine the identity and the 13C enrichment of pyrolysis products (fragments of carbohydrates, lignin, proteins and lipids). We compared the two initial litter types, needles and fine roots, to samples of the bulk soil (A horizon, < 2mm) and soil humin fraction (from chemical solubility) obtained from each microcosm 1.5y after litter addition. Pyrolysis of plant material and SOM produced 56 suitable products for isotopic analysis; of them, 15 occurred in both the litter and bulk soil, 7 in both the litter and the humin fraction and 9 in both bulk soil and the humin fraction. The pyrolysis products found in common in the plant and soil were related either to polysaccharides or were non-specific and could have originated from various precursors. The data suggest that the majority of plant inputs, both from needles or fine roots, were degraded very rapidly. In the humin fraction, the most recalcitrant pool of C in soil, with a measured turnover time of 260y (this soil), only products from the fragmentation of polysaccharides and alkyl-benzene compounds were found. Comparisons of the enrichment normalized by input level suggest little difference between the incorporation of C from needles versus fine roots into SOM. The most enriched fragments in the humin fraction were products from polysaccharides degradation, indicating a very important role of microbial processing in the stabilization of C in SOM.

Fine Root Productivity and Dynamics on a Forested Floodplain in South Carolina

Treesearch

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

2001-01-01

The highly dynamic, fine root component of forested wetland ecosystems fine root dynamics is a challenging endeavor in any system, but the difficulties are particularly evident in forested floodplains where frequent hydrologic fluctuations directly influence fine root dynamics. Fine root (53 mm) biomass, production, and turnover were estimated for three soils...

A global Fine-Root Ecology Database to address below-ground challenges in plant ecology

DOE PAGES

Iversen, Colleen M.; McCormack, M. Luke; Powell, A. Shafer; ...

2017-02-28

Variation and tradeoffs within and among plant traits are increasingly being harnessed by empiricists and modelers to understand and predict ecosystem processes under changing environmental conditions. And while fine roots play an important role in ecosystem functioning, fine-root traits are underrepresented in global trait databases. This has hindered efforts to analyze fine-root trait variation and link it with plant function and environmental conditions at a global scale. This Viewpoint addresses the need for a centralized fine-root trait database, and introduces the Fine-Root Ecology Database (FRED, http://roots.ornl.gov) which so far includes > 70 000 observations encompassing a broad range of rootmore » traits and also includes associated environmental data. FRED represents a critical step toward improving our understanding of below-ground plant ecology. For example, FRED facilitates the quantification of variation in fine-root traits across root orders, species, biomes, and environmental gradients while also providing a platform for assessments of covariation among root, leaf, and wood traits, the role of fine roots in ecosystem functioning, and the representation of fine roots in terrestrial biosphere models. There has been a continued input of observations into FRED to fill gaps in trait coverage will improve our understanding of changes in fine-root traits across space and time.« less

A global Fine-Root Ecology Database to address below-ground challenges in plant ecology

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

Iversen, Colleen M.; McCormack, M. Luke; Powell, A. Shafer

Variation and tradeoffs within and among plant traits are increasingly being harnessed by empiricists and modelers to understand and predict ecosystem processes under changing environmental conditions. And while fine roots play an important role in ecosystem functioning, fine-root traits are underrepresented in global trait databases. This has hindered efforts to analyze fine-root trait variation and link it with plant function and environmental conditions at a global scale. This Viewpoint addresses the need for a centralized fine-root trait database, and introduces the Fine-Root Ecology Database (FRED, http://roots.ornl.gov) which so far includes > 70 000 observations encompassing a broad range of rootmore » traits and also includes associated environmental data. FRED represents a critical step toward improving our understanding of below-ground plant ecology. For example, FRED facilitates the quantification of variation in fine-root traits across root orders, species, biomes, and environmental gradients while also providing a platform for assessments of covariation among root, leaf, and wood traits, the role of fine roots in ecosystem functioning, and the representation of fine roots in terrestrial biosphere models. There has been a continued input of observations into FRED to fill gaps in trait coverage will improve our understanding of changes in fine-root traits across space and time.« less

[Fine root dynamics and its relationship with soil fertility in tropical rainforests of Chocó].

PubMed

Quinto, Harley; Caicedo, Haylin; Thelis Perez, May; Moreno, Flavio

2016-12-01

The fine roots play an important role in the acquisition of water and minerals from the soil, the global carbon balance and mitigation of climate change. The dynamics (productivity and turnover) of fine roots is essential for nutrient cycling and carbon balance of forest ecosystems. The availability of soil water and nutrients has significantly determined the productivity and turnover of fine roots. It has been hypothesized that fine roots dynamics increases with the availability of soil resources in tropical forest ecosystems. To test this hypothesis in tropical rainforests of Chocó (ecosystems with the highest rainfall in the world), five one-ha permanent plots were established in the localities of Opogodó and Pacurita, where the productivity and turnover of fine roots were measured at 0-10 cm and 10-20 cm depth. The measurement of the fine root production was realized by the Ingrowth core method. The fine root turnover was measured like fine roots production divided mean annual biomass. In addition, soil fertility parameters (pH, nutrients, and texture) were measured and their association with productivity and turnover of fine roots was evaluated. It was found that the sites had nutrient-poor soils. The localities also differ in soil; Opogodó has sandy soils and flat topography, and Pacurita has clay soils, rich in aluminum and mountainous topography. In Opogodó fine root production was 6.50 ± 2.62 t/ha.yr (mean ± SD). In Pacurita, fine root production was 3.61 ± 0.88 t/ha.yr. Also in Opogodó, the fine root turnover was higher than in Pacurita (1.17 /y and 0.62 /y, respectively). Fine root turnover and production in the upper soil layers (10 cm upper soil) was considerably higher. Productivity and turnover of fine roots showed positive correlation with pH and contents of organic matter, total N, K, Mg, and sand; whereas correlations were negative with ECEC and contents of Al, silt, and clay. The percentage of sand was the parameter that best explained the variations of fine root production. The fine root turnover was negatively explained by soil Al availability. Results suggested the increase of fine root dynamics with soil fertility at a local scale, which also indicates that under the oligotrophic conditions of soils in tropical rainforests, fine roots tend to proliferate rapidly in small patches of soil rich in sand and nutrients.

A global Fine-Root Ecology Database to address below-ground challenges in plant ecology.

PubMed

Iversen, Colleen M; McCormack, M Luke; Powell, A Shafer; Blackwood, Christopher B; Freschet, Grégoire T; Kattge, Jens; Roumet, Catherine; Stover, Daniel B; Soudzilovskaia, Nadejda A; Valverde-Barrantes, Oscar J; van Bodegom, Peter M; Violle, Cyrille

2017-07-01

Variation and tradeoffs within and among plant traits are increasingly being harnessed by empiricists and modelers to understand and predict ecosystem processes under changing environmental conditions. While fine roots play an important role in ecosystem functioning, fine-root traits are underrepresented in global trait databases. This has hindered efforts to analyze fine-root trait variation and link it with plant function and environmental conditions at a global scale. This Viewpoint addresses the need for a centralized fine-root trait database, and introduces the Fine-Root Ecology Database (FRED, http://roots.ornl.gov) which so far includes > 70 000 observations encompassing a broad range of root traits and also includes associated environmental data. FRED represents a critical step toward improving our understanding of below-ground plant ecology. For example, FRED facilitates the quantification of variation in fine-root traits across root orders, species, biomes, and environmental gradients while also providing a platform for assessments of covariation among root, leaf, and wood traits, the role of fine roots in ecosystem functioning, and the representation of fine roots in terrestrial biosphere models. Continued input of observations into FRED to fill gaps in trait coverage will improve our understanding of changes in fine-root traits across space and time. © 2017 UT-Battelle LLC. New Phytologist © 2017 New Phytologist Trust.

Estimate of fine root production including the impact of decomposed roots in a Bornean tropical rainforest

NASA Astrophysics Data System (ADS)

Katayama, Ayumi; Khoon Koh, Lip; Kume, Tomonori; Makita, Naoki; Matsumoto, Kazuho; Ohashi, Mizue

2016-04-01

Considerable carbon is allocated belowground and used for respiration and production of roots. It is reported that approximately 40 % of GPP is allocated belowground in a Bornean tropical rainforest, which is much higher than those in Neotropical rainforests. This may be caused by high root production in this forest. Ingrowth core is a popular method for estimating fine root production, but recent study by Osawa et al. (2012) showed potential underestimates of this method because of the lack of consideration of the impact of decomposed roots. It is important to estimate fine root production with consideration for the decomposed roots, especially in tropics where decomposition rate is higher than other regions. Therefore, objective of this study is to estimate fine root production with consideration of decomposed roots using ingrowth cores and root litter-bag in the tropical rainforest. The study was conducted in Lambir Hills National Park in Borneo. Ingrowth cores and litter bags for fine roots were buried in March 2013. Eighteen ingrowth cores and 27 litter bags were collected in May, September 2013, March 2014 and March 2015, respectively. Fine root production was comparable to aboveground biomass increment and litterfall amount, and accounted only 10% of GPP in this study site, suggesting most of the carbon allocated to belowground might be used for other purposes. Fine root production was comparable to those in Neotropics. Decomposed roots accounted for 18% of fine root production. This result suggests that no consideration of decomposed fine roots may cause underestimate of fine root production.

Response of the Fine Root Production, Phenology, and Turnover Rate of Six Shrub Species from a Subtropical Forest to a Soil Moisture Gradient and Shading

NASA Astrophysics Data System (ADS)

Fu, X.; Dai, X.; Wang, H.

2015-12-01

Knowledge of the fine root dynamics of different life forms in forest ecosystems is critical to understanding how the overall belowground carbon cycling is affected by climate change. However, our current knowledge regarding how endogenous or exogenous factors regulate the root dynamics of understory vegetation is limited. We selected a suite of study sites representing different habitats with gradients of soil moisture and solar radiation (shading or no shading). We assessed the fine root production phenology, the total fine root production, and the turnover among six understory shrub species in a subtropical climate, and examined the responses of the fine root dynamics to gradients in the soil moisture and solar radiation. The shrubs included three evergreen species, Loropetalum chinense, Vaccinium bracteatum, and Adinandra millettii, and three deciduous species, Serissa serissoides, Rubus corchorifolius, and Lespedeza davidii. We observed that variations in the annual fine root production and turnover among species were significant in the deciduous group but not in the evergreen group. Notably, V. bracteatum and S. serissoides presented the greatest responses in terms of root phenology to gradients in the soil moisture and shading: high-moisture habitat led to a decrease and shade led to an increase in fine root production during spring. Species with smaller fine roots of the 1st+2nd-order diameter presented more sensitive responses in terms of fine root phenology to a soil moisture gradient. Species with a higher fine root nitrogen-to -carbon ratio exhibited more sensitive responses in terms of fine root annual production to shading. Soil moisture and shading did not change the annual fine root production as much as the turnover rate. The fine root dynamics of some understory shrubs varied significantly with soil moisture and solar radiation status and may be different from tree species. Our results emphasize the need to study the understory fine root dynamics in the achievement of a complete understanding of the overall belowground carbon cycling in a forest ecosystem, particularly ecosystems in which the understory fine root highly contributes to the belowground biomass.

Fine root morphological traits determine variation in root respiration of Quercus serrata.

PubMed

Makita, Naoki; Hirano, Yasuhiro; Dannoura, Masako; Kominami, Yuji; Mizoguchi, Takeo; Ishii, Hiroaki; Kanazawa, Yoichi

2009-04-01

Fine root respiration is a significant component of carbon cycling in forest ecosystems. Although fine roots differ functionally from coarse roots, these root types have been distinguished based on arbitrary diameter cut-offs (e.g., 2 or 5 mm). Fine root morphology is directly related to physiological function, but few attempts have been made to understand the relationships between morphology and respiration of fine roots. To examine relationships between respiration rates and morphological traits of fine roots (0.15-1.4 mm in diameter) of mature Quercus serrata Murr., we measured respiration of small fine root segments in the field with a portable closed static chamber system. We found a significant power relationship between mean root diameter and respiration rate. Respiration rates of roots<0.4 mm in mean diameter were high and variable, ranging from 3.8 to 11.3 nmol CO2 g(-1) s(-1), compared with those of larger diameter roots (0.4-1.4 mm), which ranged from 1.8 to 3.0 nmol CO2 g(-1) s(-1). Fine root respiration rate was positively correlated with specific root length (SRL) as well as with root nitrogen (N) concentration. For roots<0.4 mm in diameter, SRL had a wider range (11.3-80.4 m g(-1)) and was more strongly correlated with respiration rate than diameter. Our results indicate that a more detailed classification of fine roots<2.0 mm is needed to represent the heterogeneity of root respiration and to evaluate root biomass and root morphological traits.

Fine Root Abundance and Dynamics of Stone Pine (Pinus cembra) at the Alpine Treeline Is Not Impaired by Self-shading.

PubMed

Kubisch, Petra; Leuschner, Christoph; Coners, Heinz; Gruber, Andreas; Hertel, Dietrich

2017-01-01

Low temperatures are crucial for the formation of the alpine treeline worldwide. Since soil temperature in the shade of tree canopies is lower than in open sites, it was assumed that self-shading may impair the trees' root growth performance. While experiments with tree saplings demonstrate root growth impairment at soil temperatures below 5-7°C, field studies exploring the soil temperature - root growth relationship at the treeline are missing. We recorded soil temperature and fine root abundance and dynamics in shaded and sun-exposed areas under canopies of isolated Pinus cembra trees at the alpine treeline. In contrast to the mentioned assumption, we found more fine root biomass and higher fine root growth in colder than in warmer soil areas. Moreover, colder areas showed higher fine root turnover and thus lower root lifespan than warmer places. We conclude that P. cembra balances enhanced fine root mortality in cold soils with higher fine root activity and by maintaining higher fine root biomass, most likely as a response to shortage in soil resource supply. The results from our study highlight the importance of in situ measurements on mature trees to understand the fine root response and carbon allocation pattern to the thermal growth conditions at the alpine treeline.

Fine root biomass in relation to site and stand characteristics in Norway spruce and Scots pine stands.

PubMed

Helmisaari, Heljä-Sisko; Derome, John; Nöjd, Pekka; Kukkola, Mikko

2007-10-01

Variations in fine root biomass of trees and understory in 16 stands throughout Finland were examined and relationships to site and stand characteristics determined. Norway spruce fine root biomass varied between 184 and 370 g m(-2), and that of Scots pine ranged between 149 and 386 g m(-2). In northern Finland, understory roots and rhizomes (< 2 mm diameter) accounted for up to 50% of the stand total fine root biomass. Therefore, the fine root biomass of trees plus understory was larger in northern Finland in stands of both tree species, resulting in a negative relationship between fine root biomass and the temperature sum and a positive relationship between fine root biomass and the carbon:nitrogen ratio of the soil organic layer. The foliage:fine root ratio varied between 2.1 and 6.4 for Norway spruce and between 0.8 and 2.2 for Scots pine. The ratio decreased for both Norway spruce and Scots pine from south to north, as well as from fertile to more infertile site types. The foliage:fine root ratio of Norway spruce was related to basal area and stem surface area. The strong positive correlations of these three parameters with fine root nitrogen concentration implies that more fine roots are needed to maintain a certain amount of foliage when nutrient availability is low. No significant relationships were found between stand parameters and fine root biomass at the stand level, but the relationships considerably improved when both fine root biomass and stand parameters were calculated for the mean tree in the stand. When the northern and southern sites were analyzed separately, fine root biomass per tree of both species was significantly correlated with basal area and stem surface area per tree. Basal area, stem surface area and stand density can be estimated accurately and easily. Thus, our results may have value in predicting fine root biomass at the tree and stand level in boreal Norway spruce and Scots pine forests.

Effects of experimental throughfall reduction and soil warming on fine root biomass and its decomposition in a warm temperate oak forest.

PubMed

Liu, Yanchun; Liu, Shirong; Wan, Shiqiang; Wang, Jingxin; Wang, Hui; Liu, Kuan

2017-01-01

Fine root dynamics play a critical role in regulating carbon (C) cycling in terrestrial ecosystems. Examining responses of fine root biomass and its decomposition to altered precipitation pattern and climate warming is crucial to understand terrestrial C dynamics and its feedback to climate change. Fine root biomass and its decomposition rate were investigated in a warm temperate oak forest through a field manipulation experiment with throughfall reduction and soil warming conducted. Throughfall reduction significantly interacted with soil warming in affecting fine root biomass and its decomposition. Throughfall reduction substantially increased fine root biomass and its decomposition in unheated plots, but negative effects occurred in warmed plots. Soil warming significantly enhanced fine root biomass and its decomposition under ambient precipitation, but the opposite effects exhibited under throughfall reduction. Different responses in fine root biomass among different treatments could be largely attributed to soil total nitrogen (N), while fine root decomposition rate was more depended on microbial biomass C and N. Our observations indicate that decreased precipitation may offset the positive effect of soil warming on fine root biomass and decomposition. Copyright © 2016 Elsevier B.V. All rights reserved.

[Effects of tree species diversity on fine-root biomass and morphological characteristics in subtropical Castanopsis carlesii forests].

PubMed

Wang, Wei-Wei; Huang, Jin-Xue; Chen, Feng; Xiong, De-Cheng; Lu, Zheng-Li; Huang, Chao-Chao; Yang, Zhi-Jie; Chen, Guang-Shui

2014-02-01

Fine roots in the Castanopsis carlesii plantation forest (MZ), the secondary forest of C. carlesii through natural regeneration with anthropogenic promotion (AR), and the secondary forest of C. carlesii through natural regeneration (NR) in Sanming City, Fujian Province, were estimated by soil core method to determine the influence of tree species diversity on biomass, vertical distribution and morphological characteristics of fine roots. The results showed that fine root biomass for the 0-80 cm soil layer in the MZ, AR and NR were (182.46 +/- 10.81), (242.73 +/- 17.85) and (353.11 +/- 16.46) g x m(-2), respectively, showing an increased tendency with increasing tree species diversity. In the three forests, fine root biomass was significantly influenced by soil depth, and fine roots at the 0-10 cm soil layer accounted for more than 35% of the total fine root biomass. However, the interaction of stand type and soil depth on fine-root distribution was not significant, indicating no influence of tree species diversity on spatial niche segregation in fine roots. Root surface area density and root length density were the highest in NR and lowest in the MZ. Specific root length was in the order of AR > MZ > NR, while specific root surface area was in the order of NR > MZ > AR. There was no significant interaction of stand type and soil depth on specific root length and specific root surface area. Fine root morphological plasticity at the stand level had no significant response to tree species diversity.

Root architecture impacts on root decomposition rates in switchgrass

NASA Astrophysics Data System (ADS)

de Graaff, M.; Schadt, C.; Garten, C. T.; Jastrow, J. D.; Phillips, J.; Wullschleger, S. D.

2010-12-01

Roots strongly contribute to soil organic carbon accrual, but the rate of soil carbon input via root litter decomposition is still uncertain. Root systems are built up of roots with a variety of different diameter size classes, ranging from very fine to very coarse roots. Since fine roots have low C:N ratios and coarse roots have high C:N ratios, root systems are heterogeneous in quality, spanning a range of different C:N ratios. Litter decomposition rates are generally well predicted by litter C:N ratios, thus decomposition of roots may be controlled by the relative abundance of fine versus coarse roots. With this study we asked how root architecture (i.e. the relative abundance of fine versus coarse roots) affects the decomposition of roots systems in the biofuels crop switchgrass (Panicum virgatum L.). To understand how root architecture affects root decomposition rates, we collected roots from eight switchgrass cultivars (Alamo, Kanlow, Carthage, Cave-in-Rock, Forestburg, Southlow, Sunburst, Blackwell), grown at FermiLab (IL), by taking 4.8-cm diameter soil cores from on top of the crown and directly next to the crown of individual plants. Roots were carefully excised from the cores by washing and analyzed for root diameter size class distribution using WinRhizo. Subsequently, root systems of each of the plants (4 replicates per cultivar) were separated in 'fine' (0-0.5 mm), 'medium' (0.5-1 mm) and 'coarse' roots (1-2.5 mm), dried, cut into 0.5 cm (medium and coarse roots) and 2 mm pieces (fine roots), and incubated for 90 days. For each of the cultivars we established five root-treatments: 20g of soil was amended with 0.2g of (1) fine roots, (2) medium roots, (3) coarse roots, (4) a 1:1:1 mixture of fine, medium and coarse roots, and (5) a mixture combining fine, medium and coarse roots in realistic proportions. We measured CO2 respiration at days 1, 3, 7, 15, 30, 60 and 90 during the experiment. The 13C signature of the soil was -26‰, and the 13C signature of plants was -12‰, enabling us to differentiate between root-derived C and native SOM-C respiration. We found that the relative abundance of fine, medium and coarse roots were significantly different among cultivars. Root systems of Alamo, Kanlow and Cave-in-Rock were characterized by a large abundance of coarse-, relative to fine roots, whereas Carthage, Forestburg and Blackwell had a large abundance of fine, relative to coarse roots. Fine roots had a 28% lower C:N ratio than medium and coarse roots. These differences led to different root decomposition rates. We conclude that root architecture should be taken into account when predicting root decomposition rates; enhanced understanding of the mechanisms of root decomposition will improve model predictions of C input to soil organic matter.

Fine root productivity varies along nitrogen and phosphorus gradients in high-rainfall mangrove forests of Micronesia

USGS Publications Warehouse

Cormier, Nicole; Twilley, Robert R.; Ewel, Katherine C.; Krauss, Ken W.

2015-01-01

Belowground biomass is thought to account for much of the total biomass in mangrove forests and may be related to soil fertility. The Yela River and the Sapwalap River, Federated States of Micronesia, contain a natural soil resource gradient defined by total phosphorus (P) density ranging from 0.05 to 0.42 mg cm−3 in different hydrogeomorphic settings. We used this fertility gradient to test the hypothesis that edaphic conditions constrain mangrove productivity through differential allocation of biomass to belowground roots. We removed sequential cores and implanted root ingrowth bags to measure in situ biomass and productivity, respectively. Belowground root biomass values ranged among sites from 0.448 ± 0.096 to 2.641 ± 0.534 kg m−2. Root productivity (roots ≤20 mm) did not vary significantly along the gradient (P = 0.3355) or with P fertilization after 6 months (P = 0.2968). Fine root productivity (roots ≤2 mm), however, did vary significantly among sites (P = 0.0363) and ranged from 45.88 ± 21.37 to 118.66 ± 38.05 g m−2 year−1. The distribution of total standing root biomass and fine root productivity followed patterns of N:P ratios as hypothesized, with larger root mass generally associated with lower relative P concentrations. Many of the processes of nutrient acquisition reported from nutrient-limited mangrove forests may also occur in forests of greater biomass and productivity when growing along soil nutrient gradients.

[Effects of soil warming on specific respiration rate and non-structural carbohydrate concentration in fine roots of Chinese fir seedlings].

PubMed

Song, Tao Tao; Chen, Guang Shui; Shi, Shun Zeng; Guo, Run Quan; Zheng, Xin; Xiong, De Cheng; Chen, Wang Yuan; Chen, Ting Ting

2018-03-01

A field mesocosm experiment with Chinese fir (Cunninghamia lanceolata) seedlings was conducted in Chenda State-Owned Forest Farm, Sanming, Fujian Province. The effects of soil warming (ambient +5 ℃) on specific respiration rates and nonstructural carbohydrate (NSC) concentrations in fine roots were measured by the ingrowth core method, to reveal the belowground responses and the adaptability of Chinese fir to global warming. The results showed that soil warming caused significant changes of fine root NSC in the second year. The NSC and starch concentrations in 0-1 mm fine roots, and the NSC and sugar concentrations in 1-2 mm fine roots decreased signifi-cantly in January. The NSC, sugar and starch concentrations in 0-1 mm roots and the starch concentration in 1-2 mm roots increased in July. Soil warming had no significant effect on fine root NSC in the third year. The specific root respiration rate of the 0-1 mm roots significantly increased in July of the second year but significantly decreased in July of the third year in the warmed plots. Compared with the 0-1 mm roots, soil warming had no significant effect on the specific root respiration rate of the 1-2 mm roots. In conclusion, the responses of fine root respiration to soil warming depended on the duration of warming. Fine root respiration partly acclimated to soil warming with increasing duration of soil warming, which kept fine root NSC being relatively stable.

Fine Root Abundance and Dynamics of Stone Pine (Pinus cembra) at the Alpine Treeline Is Not Impaired by Self-shading

PubMed Central

Kubisch, Petra; Leuschner, Christoph; Coners, Heinz; Gruber, Andreas; Hertel, Dietrich

2017-01-01

Low temperatures are crucial for the formation of the alpine treeline worldwide. Since soil temperature in the shade of tree canopies is lower than in open sites, it was assumed that self-shading may impair the trees’ root growth performance. While experiments with tree saplings demonstrate root growth impairment at soil temperatures below 5–7°C, field studies exploring the soil temperature – root growth relationship at the treeline are missing. We recorded soil temperature and fine root abundance and dynamics in shaded and sun-exposed areas under canopies of isolated Pinus cembra trees at the alpine treeline. In contrast to the mentioned assumption, we found more fine root biomass and higher fine root growth in colder than in warmer soil areas. Moreover, colder areas showed higher fine root turnover and thus lower root lifespan than warmer places. We conclude that P. cembra balances enhanced fine root mortality in cold soils with higher fine root activity and by maintaining higher fine root biomass, most likely as a response to shortage in soil resource supply. The results from our study highlight the importance of in situ measurements on mature trees to understand the fine root response and carbon allocation pattern to the thermal growth conditions at the alpine treeline. PMID:28469633

Climate, soil and plant functional types as drivers of global fine-root trait variation

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

Freschet, Grégoire T.; Valverde-Barrantes, Oscar J.; Tucker, Caroline M.

Ecosystem functioning relies heavily on below-ground processes, which are largely regulated by plant fine-roots and their functional traits. However, our knowledge of fine-root trait distribution relies to date on local- and regional-scale studies with limited numbers of species, growth forms and environmental variation. We compiled a world-wide fine-root trait dataset, featuring 1115 species from contrasting climatic areas, phylogeny and growth forms to test a series of hypotheses pertaining to the influence of plant functional types, soil and climate variables, and the degree of manipulation of plant growing conditions on species fine-root trait variation. Most particularly, we tested the competing hypothesesmore » that fine-root traits typical of faster return on investment would be most strongly associated with conditions of limiting versus favourable soil resource availability. We accounted for both data source and species phylogenetic relatedness. We demonstrate that: (i) Climate conditions promoting soil fertility relate negatively to fine-root traits favouring fast soil resource acquisition, with a particularly strong positive effect of temperature on fine-root diameter and negative effect on specific root length (SRL), and a negative effect of rainfall on root nitrogen concentration; (ii) Soil bulk density strongly influences species fine-root morphology, by favouring thicker, denser fine-roots; (iii) Fine-roots from herbaceous species are on average finer and have higher SRL than those of woody species, and N 2-fixing capacity positively relates to root nitrogen; and (iv) Plants growing in pots have higher SRL than those grown in the field. Synthesis. This study reveals both the large variation in fine-root traits encountered globally and the relevance of several key plant functional types and soil and climate variables for explaining a substantial part of this variation. Climate, particularly temperature, and plant functional types were the two strongest predictors of fine-root trait variation. High trait variation occurred at local scales, suggesting that wide-ranging below-ground resource economics strategies are viable within most climatic areas and soil conditions.« less

Climate, soil and plant functional types as drivers of global fine-root trait variation

DOE PAGES

Freschet, Grégoire T.; Valverde-Barrantes, Oscar J.; Tucker, Caroline M.; ...

2017-03-08

Ecosystem functioning relies heavily on below-ground processes, which are largely regulated by plant fine-roots and their functional traits. However, our knowledge of fine-root trait distribution relies to date on local- and regional-scale studies with limited numbers of species, growth forms and environmental variation. We compiled a world-wide fine-root trait dataset, featuring 1115 species from contrasting climatic areas, phylogeny and growth forms to test a series of hypotheses pertaining to the influence of plant functional types, soil and climate variables, and the degree of manipulation of plant growing conditions on species fine-root trait variation. Most particularly, we tested the competing hypothesesmore » that fine-root traits typical of faster return on investment would be most strongly associated with conditions of limiting versus favourable soil resource availability. We accounted for both data source and species phylogenetic relatedness. We demonstrate that: (i) Climate conditions promoting soil fertility relate negatively to fine-root traits favouring fast soil resource acquisition, with a particularly strong positive effect of temperature on fine-root diameter and negative effect on specific root length (SRL), and a negative effect of rainfall on root nitrogen concentration; (ii) Soil bulk density strongly influences species fine-root morphology, by favouring thicker, denser fine-roots; (iii) Fine-roots from herbaceous species are on average finer and have higher SRL than those of woody species, and N 2-fixing capacity positively relates to root nitrogen; and (iv) Plants growing in pots have higher SRL than those grown in the field. Synthesis. This study reveals both the large variation in fine-root traits encountered globally and the relevance of several key plant functional types and soil and climate variables for explaining a substantial part of this variation. Climate, particularly temperature, and plant functional types were the two strongest predictors of fine-root trait variation. High trait variation occurred at local scales, suggesting that wide-ranging below-ground resource economics strategies are viable within most climatic areas and soil conditions.« less

Fine root dynamics and trace gas fluxes in two lowland tropical forest soils.

Treesearch

WHENDEE L. SILVER; ANDREW W. THOMPSON; MEGAN E . MCGRODDY; RUTH K. VARNER; JADSON D. DIAS; HUDSON SILVA; CRILL PATRICK M.; MICHAEL KELLER

2005-01-01

Fine root dynamics have the potential to contribute significantly to ecosystem-scale biogeochemical cycling, including the production and emission of greenhouse gases. This is particularly true in tropical forests which are often characterized as having large fine root biomass and rapid rates of root production and decomposition. We examined patterns in fine root...

Elevated CO2 and O3 effects on fine-root survivorship in ponderosa pine mesocosms.

PubMed

Phillips, Donald L; Johnson, Mark G; Tingey, David T; Storm, Marjorie J

2009-07-01

Atmospheric carbon dioxide (CO(2)) and ozone (O(3)) concentrations are rising, which may have opposing effects on tree C balance and allocation to fine roots. More information is needed on interactive CO(2) and O(3) effects on roots, particularly fine-root life span, a critical demographic parameter and determinant of soil C and N pools and cycling rates. We conducted a study in which ponderosa pine (Pinus ponderosa) seedlings were exposed to two levels of CO(2) and O(3) in sun-lit controlled-environment mesocosms for 3 years. Minirhizotrons were used to monitor individual fine roots in three soil horizons every 28 days. Proportional hazards regression was used to analyze effects of CO(2), O(3), diameter, depth, and season of root initiation on fine-root survivorship. More fine roots were produced in the elevated CO(2) treatment than in ambient CO(2). Elevated CO(2), increasing root diameter, and increasing root depth all significantly increased fine-root survivorship and median life span. Life span was slightly, but not significantly, lower in elevated O(3), and increased O(3) did not reduce the effect of elevated CO(2). Median life spans varied from 140 to 448 days depending on the season of root initiation. These results indicate the potential for elevated CO(2) to increase the number of fine roots and their residence time in the soil, which is also affected by root diameter, root depth, and phenology.

Nine Years of Irrigation Cause Vegetation and Fine Root Shifts in a Water-Limited Pine Forest

PubMed Central

Herzog, Claude; Steffen, Jan; Graf Pannatier, Elisabeth; Hajdas, Irka; Brunner, Ivano

2014-01-01

Scots pines (Pinus sylvestris L.) in the inner-Alpine dry valleys of Switzerland have suffered from increased mortality during the past decades, which has been caused by longer and more frequent dry periods. In addition, a proceeding replacement of Scots pines by pubescent oaks (Quercus pubescens Willd.) has been observed. In 2003, an irrigation experiment was performed to track changes by reducing drought pressure on the natural pine forest. After nine years of irrigation, we observed major adaptations in the vegetation and shifts in Scots pine fine root abundance and structure. Irrigation permitted new plant species to assemble and promote canopy closure with a subsequent loss of herb and moss coverage. Fine root dry weight increased under irrigation and fine roots had a tendency to elongate. Structural composition of fine roots remained unaffected by irrigation, expressing preserved proportions of cellulose, lignin and phenolic substances. A shift to a more negative δ13C signal in the fine root C indicates an increased photosynthetic activity in irrigated pine trees. Using radiocarbon (14C) measurement, a reduced mean age of the fine roots in irrigated plots was revealed. The reason for this is either an increase in newly produced fine roots, supported by the increase in fine root biomass, or a reduced lifespan of fine roots which corresponds to an enhanced turnover rate. Overall, the responses belowground to irrigation are less conspicuous than the more rapid adaptations aboveground. Lagged and conservative adaptations of tree roots with decadal lifespans are challenging to detect, hence demanding for long-term surveys. Investigations concerning fine root turnover rate and degradation processes under a changing climate are crucial for a complete understanding of C cycling. PMID:24802642

Fine root mercury heterogeneity: metabolism of lower-order roots as an effective route for mercury removal.

PubMed

Wang, Jun-Jian; Guo, Ying-Ying; Guo, Da-Li; Yin, Sen-Lu; Kong, De-Liang; Liu, Yang-Sheng; Zeng, Hui

2012-01-17

Fine roots are critical components for plant mercury (Hg) uptake and removal, but the patterns of Hg distribution and turnover within the heterogeneous fine root components and their potential limiting factors are poorly understood. Based on root branching structure, we studied the total Hg (THg) and its cellular partitioning in fine roots in 6 Chinese subtropical trees species and the impacts of root morphological and stoichiometric traits on Hg partitioning. The THg concentration generally decreased with increasing root order, and was higher in cortex than in stele. This concentration significantly correlated with root length, diameter, specific root length, specific root area, and nitrogen concentration, whereas its cytosolic fraction (accounting for <10% of THg) correlated with root carbon and sulfur concentrations. The estimated Hg return flux from dead fine roots outweighed that from leaf litter, and ephemeral first-order roots that constituted 7.2-22.3% of total fine root biomass may have contributed most to this flux (39-71%, depending on tree species and environmental substrate). Our results highlight the high capacity of Hg stabilization and Hg return by lower-order roots and demonstrate that turnover of lower-order roots may be an effective strategy of detoxification in perennial tree species.

The effect of limited availability of N or water on C allocation to fine roots and annual fine root turnover in Alnus incana and Salix viminalis.

PubMed

Rytter, Rose-Marie

2013-09-01

The effect of limited nitrogen (N) or water availability on fine root growth and turnover was examined in two deciduous species, Alnus incana L. and Salix viminalis L., grown under three different regimes: (i) supply of N and water in amounts which would not hamper growth, (ii) limited N supply and (iii) limited water supply. Plants were grown outdoors during three seasons in covered and buried lysimeters placed in a stand structure and filled with quartz sand. Computer-controlled irrigation and fertilization were supplied through drip tubes. Production and turnover of fine roots were estimated by combining minirhizotron observations and core sampling, or by sequential core sampling. Annual turnover rates of fine roots <1 mm (5-6 year(-1)) and 1-2 mm (0.9-2.8 year(-1)) were not affected by changes in N or water availability. Fine root production (<1 mm) differed between Alnus and Salix, and between treatments in Salix; i.e., absolute length and biomass production increased in the order: water limited < unlimited < N limited. Few treatment effects were detected for fine roots 1-2 mm. Proportionally more C was allocated to fine roots (≤2 mm) in N or water-limited Salix; 2.7 and 2.3 times the allocation to fine roots in the unlimited regime, respectively. Estimated input to soil organic carbon increased by ca. 20% at N limitation in Salix. However, future studies on fine root decomposition under various environmental conditions are required. Fine root growth responses to N or water limitation were less pronounced in Alnus, thus indicating species differences caused by N-fixing capacity and slower initial growth in Alnus, or higher fine root plasticity in Salix. A similar seasonal growth pattern across species and treatments suggested the influence of outer stimuli, such as temperature and light.

Differences in Fine-Root Biomass of Trees and Understory Vegetation among Stand Types in Subtropical Forests

PubMed Central

Fu, Xiaoli; Wang, Jianlei; Di, Yuebao; Wang, Huimin

2015-01-01

Variation of total fine-root biomass among types of tree stands has previously been attributed to the characteristics of the stand layers. The effects of the understory vegetation on total fine-root biomass are less well studied. We examined the variation of total fine-root biomass in subtropical tree stands at two sites of Datian and Huitong in China. The two sites have similar humid monsoon climate but different soil organic carbon. One examination compared two categories of basal areas (high vs. low basal area) in stands of single species. A second examination compared single-species and mixed stands with comparable basal areas. Low basal area did not correlate with low total fine-root biomass in the single-species stands. The increase in seedling density but decrease in stem density for the low basal area stands at Datian and the quite similar stand structures for the basal-area contrast at Huitong helped in the lack of association between basal area and total fine-root biomass at the two sites, respectively. The mixed stands also did not yield higher total fine-root biomasses. In addition to the lack of niche complementarity between tree species, the differences in stem and seedling densities and the belowground competition between the tree and non-tree species also contributed to the similarity of the total fine-root biomasses in the mixed and single-species stands. Across stand types, the more fertile site Datian yielded higher tree, non-tree and total fine-root biomasses than Huitong. However, the contribution of non-tree fine-root biomass to the total fine-root biomass was higher at Huitong (29.4%) than that at Datian (16.7%). This study suggests that the variation of total fine-root biomass across stand types not only was associated with the characteristics of trees, but also may be highly dependent on the understory layer. PMID:26047358

Differences in Fine-Root Biomass of Trees and Understory Vegetation among Stand Types in Subtropical Forests.

PubMed

Fu, Xiaoli; Wang, Jianlei; Di, Yuebao; Wang, Huimin

2015-01-01

Variation of total fine-root biomass among types of tree stands has previously been attributed to the characteristics of the stand layers. The effects of the understory vegetation on total fine-root biomass are less well studied. We examined the variation of total fine-root biomass in subtropical tree stands at two sites of Datian and Huitong in China. The two sites have similar humid monsoon climate but different soil organic carbon. One examination compared two categories of basal areas (high vs. low basal area) in stands of single species. A second examination compared single-species and mixed stands with comparable basal areas. Low basal area did not correlate with low total fine-root biomass in the single-species stands. The increase in seedling density but decrease in stem density for the low basal area stands at Datian and the quite similar stand structures for the basal-area contrast at Huitong helped in the lack of association between basal area and total fine-root biomass at the two sites, respectively. The mixed stands also did not yield higher total fine-root biomasses. In addition to the lack of niche complementarity between tree species, the differences in stem and seedling densities and the belowground competition between the tree and non-tree species also contributed to the similarity of the total fine-root biomasses in the mixed and single-species stands. Across stand types, the more fertile site Datian yielded higher tree, non-tree and total fine-root biomasses than Huitong. However, the contribution of non-tree fine-root biomass to the total fine-root biomass was higher at Huitong (29.4%) than that at Datian (16.7%). This study suggests that the variation of total fine-root biomass across stand types not only was associated with the characteristics of trees, but also may be highly dependent on the understory layer.

The contribution of fine roots to peatland stability under changing environmental conditions

NASA Astrophysics Data System (ADS)

Malhotra, A.; Brice, D. J.; Childs, J.; Phillips, J.; Hanson, P. J.; Iversen, C. M.

2017-12-01

Fine-root production and traits are closely linked with ecosystem nutrient and water fluxes, and may regulate these fluxes in response to environmental change. Plant strategies can shift to favoring below- over aboveground biomass allocation when nutrients or moisture are limited. Fine-roots traits such as root tissue density (RTD) or specific root length (SRL) can also adapt to the environment, for example, by maximizing the area of soil exploited by decreasing RTD and increasing SRL during dry conditions. Fine-root trait plasticity could contribute to the stability of peatland carbon function in response to environmental change. However, the extent and mechanisms of peatland fine-root plasticity are unknown. We investigated fine-root growth and traits and their link to environmental factors and aboveground dynamics at SPRUCE (Spruce and Peatland Responses Under Changing Environments), a warming and elevated CO2 (eCO2) experiment in an ombrotrophic peatland. In the first growing season of whole ecosystem warming, fine-root production increased with warming and drying. Above- versus belowground allocation strategies varied by plant functional type (PFT). In shrubs, contrary to our expectation, aboveground- to fine-root production allocation ratio increased with dryer conditions, perhaps as a response to a concurrent increase in nutrients. Trait response hypotheses were largely supported, with RTD decreasing and SRL increasing with warming; however, response varied among PFTs. Once eCO2 was turned on in the second growing season, preliminary results suggest interactive effects of warming and eCO2 on total fine-root production: production decreased or increased with warming in ambient or elevated CO2 plots, respectively. Both trait and production responses to warming and eCO2 varied by microtopography and depth. Our results highlight plasticity of fine-root traits and biomass allocation strategies; the extent and mechanism of which varies by PFT. We will summarize our results using a trait-based approach as a first step toward modeling fine-root contributions to peatland carbon stability in response to environmental change.

High-mass-resolution MALDI mass spectrometry imaging reveals detailed spatial distribution of metabolites and lipids in roots of barley seedlings in response to salinity stress.

PubMed

Sarabia, Lenin D; Boughton, Berin A; Rupasinghe, Thusitha; van de Meene, Allison M L; Callahan, Damien L; Hill, Camilla B; Roessner, Ute

2018-01-01

Mass spectrometry imaging (MSI) is a technology that enables the visualization of the spatial distribution of hundreds to thousands of metabolites in the same tissue section simultaneously. Roots are below-ground plant organs that anchor plants to the soil, take up water and nutrients, and sense and respond to external stresses. Physiological responses to salinity are multifaceted and have predominantly been studied using whole plant tissues that cannot resolve plant salinity responses spatially. This study aimed to use a comprehensive approach to study the spatial distribution and profiles of metabolites, and to quantify the changes in the elemental content in young developing barley seminal roots before and after salinity stress. Here, we used a combination of liquid chromatography-mass spectrometry (LC-MS), inductively coupled plasma mass spectrometry (ICP-MS), and matrix-assisted laser desorption/ionization (MALDI-MSI) platforms to profile and analyze the spatial distribution of ions, metabolites and lipids across three anatomically different barley root zones before and after a short-term salinity stress (150 mM NaCl). We localized, visualized and discriminated compounds in fine detail along longitudinal root sections and compared ion, metabolite, and lipid composition before and after salt stress. Large changes in the phosphatidylcholine (PC) profiles were observed as a response to salt stress with PC 34:n showing an overall reduction in salt treated roots. ICP-MS analysis quantified changes in the elemental content of roots with increases of Na + and decreases of K + content. Our results established the suitability of combining three mass spectrometry platforms to analyze and map ionic and metabolic responses to salinity stress in plant roots and to elucidate tolerance mechanisms in response to abiotic stress, such as salinity stress.

Fine root dynamics along an elevational gradient in tropical Amazonian and Andean forests

NASA Astrophysics Data System (ADS)

Girardin, C. A. J.; Aragão, L. E. O. C.; Malhi, Y.; Huaraca Huasco, W.; Metcalfe, D. B.; Durand, L.; Mamani, M.; Silva-Espejo, J. E.; Whittaker, R. J.

2013-01-01

The key role of tropical forest belowground carbon stocks and fluxes is well recognised as one of the main components of the terrestrial ecosystem carbon cycle. This study presents the first detailed investigation of spatial and temporal patterns of fine root stocks and fluxes in tropical forests along an elevational gradient, ranging from the Peruvian Andes (3020 m) to lowland Amazonia (194 m), with mean annual temperatures of 11.8°C to 26.4 °C and annual rainfall values of 1900 to 1560 mm yr-1, respectively. Specifically, we analyse abiotic parameters controlling fine root dynamics, fine root growth characteristics, and seasonality of net primary productivity along the elevation gradient. Root and soil carbon stocks were measured by means of soil cores, and fine root productivity was recorded using rhizotron chambers and ingrowth cores. We find that mean annual fine root below ground net primary productivity in the montane forests (0-30 cm depth) ranged between 4.27±0.56 Mg C ha-1 yr-1 (1855 m) and 1.72±0.87 Mg C ha-1 yr-1 (3020 m). These values include a correction for finest roots (<0.6 mm diameter), which we suspect are under sampled, resulting in an underestimation of fine roots by up to 31% in current ingrowth core counting methods. We investigate the spatial and seasonal variation of fine root dynamics using soil depth profiles and an analysis of seasonal amplitude along the elevation gradient. We report a stronger seasonality of NPPFineRoot within the cloud immersion zone, most likely synchronised to seasonality of solar radiation. Finally, we provide the first insights into root growth characteristics along a tropical elevation transect: fine root area and fine root length increase significantly in the montane cloud forest. These insights into belowground carbon dynamics of tropical lowland and montane forests have significant implications for our understanding of the global tropical forest carbon cycle.

Litter Decomposition in a Semiarid Dune Grassland: Neutral Effect of Water Supply and Inhibitory Effect of Nitrogen Addition.

PubMed

Li, Yulin; Ning, Zhiying; Cui, Duo; Mao, Wei; Bi, Jingdong; Zhao, Xueyong

2016-01-01

The decomposition of plant material in arid ecosystems is considered to be substantially controlled by water and N availability. The responses of litter decomposition to external N and water, however, remain controversial, and the interactive effects of supplementary N and water also have been largely unexamined. A 3.5-year field experiment with supplementary nitrogen and water was conducted to assess the effects of N and water addition on mass loss and nitrogen release in leaves and fine roots of three dominant plant species (i.e., Artemisia halondendron, Setaria viridis, and Phragmites australis) with contrasting substrate chemistry (e.g. N concentration, lignin content in this study) in a desertified dune grassland of Inner Mongolia, China. The treatments included N addition, water addition, combination of N and water, and an untreated control. The decomposition rate in both leaves and roots was related to the initial litter N and lignin concentrations of the three species. However, litter quality did not explain the slower mass loss in roots than in leaves in the present study, and thus warrant further research. Nitrogen addition, either alone or in combination with water, significantly inhibited dry mass loss and N release in the leaves and roots of the three species, whereas water input had little effect on the decomposition of leaf litter and fine roots, suggesting that there was no interactive effect of supplementary N and water on litter decomposition in this system. Furthermore, our results clearly indicate that the inhibitory effects of external N on dry mass loss and nitrogen release are relatively strong in high-lignin litter compared with low-lignin litter. These findings suggest that increasing precipitation hardly facilitates ecosystem carbon turnover but atmospheric N deposition can enhance carbon sequestration and nitrogen retention in desertified dune grasslands of northern China. Additionally, litter quality of plant species should be considered when modelling the carbon cycle and nutrient dynamics of this system.

Litter Decomposition in a Semiarid Dune Grassland: Neutral Effect of Water Supply and Inhibitory Effect of Nitrogen Addition

PubMed Central

Li, Yulin; Ning, Zhiying; Cui, Duo; Mao, Wei; Bi, Jingdong; Zhao, Xueyong

2016-01-01

Background The decomposition of plant material in arid ecosystems is considered to be substantially controlled by water and N availability. The responses of litter decomposition to external N and water, however, remain controversial, and the interactive effects of supplementary N and water also have been largely unexamined. Methodology/Principal Findings A 3.5-year field experiment with supplementary nitrogen and water was conducted to assess the effects of N and water addition on mass loss and nitrogen release in leaves and fine roots of three dominant plant species (i.e., Artemisia halondendron, Setaria viridis, and Phragmites australis) with contrasting substrate chemistry (e.g. N concentration, lignin content in this study) in a desertified dune grassland of Inner Mongolia, China. The treatments included N addition, water addition, combination of N and water, and an untreated control. The decomposition rate in both leaves and roots was related to the initial litter N and lignin concentrations of the three species. However, litter quality did not explain the slower mass loss in roots than in leaves in the present study, and thus warrant further research. Nitrogen addition, either alone or in combination with water, significantly inhibited dry mass loss and N release in the leaves and roots of the three species, whereas water input had little effect on the decomposition of leaf litter and fine roots, suggesting that there was no interactive effect of supplementary N and water on litter decomposition in this system. Furthermore, our results clearly indicate that the inhibitory effects of external N on dry mass loss and nitrogen release are relatively strong in high-lignin litter compared with low-lignin litter. Conclusion/Significance These findings suggest that increasing precipitation hardly facilitates ecosystem carbon turnover but atmospheric N deposition can enhance carbon sequestration and nitrogen retention in desertified dune grasslands of northern China. Additionally, litter quality of plant species should be considered when modelling the carbon cycle and nutrient dynamics of this system. PMID:27617439

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

NASA Astrophysics Data System (ADS)

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

2012-12-01

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

Tree Age Effects on Fine Root Biomass and Morphology over Chronosequences of Fagus sylvatica, Quercus robur and Alnus glutinosa Stands

PubMed Central

Jagodzinski, Andrzej M.; Ziółkowski, Jędrzej; Warnkowska, Aleksandra; Prais, Hubert

2016-01-01

There are few data on fine root biomass and morphology change in relation to stand age. Based on chronosequences for beech (9–140 years old), oak (11–140 years) and alder (4–76 years old) we aimed to examine how stand age affects fine root biomass and morphology. Soil cores from depths of 0–15 cm and 16–30 cm were used for the study. In contrast to previously published studies that suggested that maximum fine root biomass is reached at the canopy closure stage of stand development, we found almost linear increases of fine root biomass over stand age within the chronosequences. We did not observe any fine root biomass peak in the canopy closure stage. However, we found statistically significant increases of mean fine root biomass for the average individual tree in each chronosequence. Mean fine root biomass (0–30 cm) differed significantly among tree species chronosequences studied and was 4.32 Mg ha-1, 3.71 Mg ha-1 and 1.53 Mg ha-1, for beech, oak and alder stands, respectively. The highest fine root length, surface area, volume and number of fine root tips (0–30 cm soil depth), expressed on a stand area basis, occurred in beech stands, with medium values for oak stands and the lowest for alder stands. In the alder chronosequence all these values increased with stand age, in the beech chronosequence they decreased and in the oak chronosequence they increased until ca. 50 year old stands and then reached steady-state. Our study has proved statistically significant negative relationships between stand age and specific root length (SRL) in 0–30 cm soil depth for beech and oak chronosequences. Mean SRLs for each chronosequence were not significantly different among species for either soil depth studied. The results of this study indicate high fine root plasticity. Although only limited datasets are currently available, these data have provided valuable insight into fine root biomass and morphology of beech, oak and alder stands. PMID:26859755

A global analysis of fine root production as affected by soil nitrogen and phosphorus.

PubMed

Yuan, Z Y; Chen, Han Y H

2012-09-22

Fine root production is the largest component of belowground production and plays substantial roles in the biogeochemical cycles of terrestrial ecosystems. The increasing availability of nitrogen (N) and phosphorus (P) due to human activities is expected to increase aboveground net primary production (ANNP), but the response of fine root production to N and P remains unclear. If roots respond to nutrients as ANNP, fine root production is anticipated to increase with increasing soil N and P. Here, by synthesizing data along the nutrient gradient from 410 natural habitats and from 469 N and/or P addition experiments, we showed that fine root production increased in terrestrial ecosystems with an average increase along the natural N gradient of up to 0.5 per cent with increasing soil N. Fine root production also increased with soil P in natural conditions, particularly at P < 300 mg kg(-1). With N, P and combined N + P addition, fine root production increased by a global average of 27, 21 and 40 per cent, respectively. However, its responses differed among ecosystems and soil types. The global average increases in fine root production are lower than those of ANNP, indicating that above- and belowground counterparts are coupled, but production allocation shifts more to aboveground with higher soil nutrients. Our results suggest that the increasing fertilizer use and combined N deposition at present and in the future will stimulate fine root production, together with ANPP, probably providing a significant influence on atmospheric CO(2) emissions.

Changes in fine-root production, phenology and spatial distribution in response to N application in irrigated sweet cherry trees.

PubMed

Artacho, Pamela; Bonomelli, Claudia

2016-05-01

Factors regulating fine-root growth are poorly understood, particularly in fruit tree species. In this context, the effects of N addition on the temporal and spatial distribution of fine-root growth and on the fine-root turnover were assessed in irrigated sweet cherry trees. The influence of other exogenous and endogenous factors was also examined. The rhizotron technique was used to measure the length-based fine-root growth in trees fertilized at two N rates (0 and 60 kg ha(-1)), and the above-ground growth, leaf net assimilation, and air and soil variables were simultaneously monitored. N fertilization exerted a basal effect throughout the season, changing the magnitude, temporal patterns and spatial distribution of fine-root production and mortality. Specifically, N addition enhanced the total fine-root production by increasing rates and extending the production period. On average, N-fertilized trees had a length-based production that was 110-180% higher than in control trees, depending on growing season. Mortality was proportional to production, but turnover rates were inconsistently affected. Root production and mortality was homogeneously distributed in the soil profile of N-fertilized trees while control trees had 70-80% of the total fine-root production and mortality concentrated below 50 cm depth. Root mortality rates were associated with soil temperature and water content. In contrast, root production rates were primarily under endogenous control, specifically through source-sink relationships, which in turn were affected by N supply through changes in leaf photosynthetic level. Therefore, exogenous and endogenous factors interacted to control the fine-root dynamics of irrigated sweet cherry trees. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Changes in fine-root production, phenology and spatial distribution in response to N application in irrigated sweet cherry trees

PubMed Central

Artacho, Pamela; Bonomelli, Claudia

2016-01-01

Factors regulating fine-root growth are poorly understood, particularly in fruit tree species. In this context, the effects of N addition on the temporal and spatial distribution of fine-root growth and on the fine-root turnover were assessed in irrigated sweet cherry trees. The influence of other exogenous and endogenous factors was also examined. The rhizotron technique was used to measure the length-based fine-root growth in trees fertilized at two N rates (0 and 60 kg ha−1), and the above-ground growth, leaf net assimilation, and air and soil variables were simultaneously monitored. N fertilization exerted a basal effect throughout the season, changing the magnitude, temporal patterns and spatial distribution of fine-root production and mortality. Specifically, N addition enhanced the total fine-root production by increasing rates and extending the production period. On average, N-fertilized trees had a length-based production that was 110–180% higher than in control trees, depending on growing season. Mortality was proportional to production, but turnover rates were inconsistently affected. Root production and mortality was homogeneously distributed in the soil profile of N-fertilized trees while control trees had 70–80% of the total fine-root production and mortality concentrated below 50 cm depth. Root mortality rates were associated with soil temperature and water content. In contrast, root production rates were primarily under endogenous control, specifically through source–sink relationships, which in turn were affected by N supply through changes in leaf photosynthetic level. Therefore, exogenous and endogenous factors interacted to control the fine-root dynamics of irrigated sweet cherry trees. PMID:26888890

Carbon Allocation into Different Fine-Root Classes of Young Abies alba Trees Is Affected More by Phenology than by Simulated Browsing

PubMed Central

Endrulat, Tina; Buchmann, Nina; Brunner, Ivano

2016-01-01

Abies alba (European silver fir) was used to investigate possible effects of simulated browsing on C allocation belowground by 13CO2 pulse-labelling at spring, summer or autumn, and by harvesting the trees at the same time point of the labelling or at a later season for biomass and for 13C-allocation into the fine-root system. Before budburst in spring, the leader shoots and 50% of all lateral shoots of half of the investigated 5-year old Abies alba saplings were clipped to simulate browsing. At harvest, different fine-root classes were separated, and starch as an important storage compartment was analysed for concentrations. The phenology had a strong effect on the allocation of the 13C-label from shoots to roots. In spring, shoots did not supply the fine-roots with high amounts of the 13C-label, because the fine-roots contained less than 1% of the applied 13C. In summer and autumn, however, shoots allocated relatively high amounts of the 13C-label to the fine roots. The incorporation of the 13C-label as structural C or as starch into the roots is strongly dependent on the root type and the root diameter. In newly formed fine roots, 3–5% of the applied 13C was incorporated, whereas 1–3% in the ≤0.5 mm root class and 1–1.5% in the >0.5–1.0 mm root class were recorded. Highest 13C-enrichment in the starch was recorded in the newly formed fine roots in autumn. The clipping treatment had a significant positive effect on the amount of allocated 13C-label to the fine roots after the spring labelling, with high relative 13C-contents observed in the ≤0.5 mm and the >0.5–1.0 mm fine-root classes of clipped trees. No effects of the clipping were observed after summer and autumn labelling in the 13C-allocation patterns. Overall, our data imply that the season of C assimilation and, thus, the phenology of trees is the main determinant of the C allocation from shoots to roots and is clearly more important than browsing. PMID:27123860

Carbon Allocation into Different Fine-Root Classes of Young Abies alba Trees Is Affected More by Phenology than by Simulated Browsing.

PubMed

Endrulat, Tina; Buchmann, Nina; Brunner, Ivano

2016-01-01

Abies alba (European silver fir) was used to investigate possible effects of simulated browsing on C allocation belowground by 13CO2 pulse-labelling at spring, summer or autumn, and by harvesting the trees at the same time point of the labelling or at a later season for biomass and for 13C-allocation into the fine-root system. Before budburst in spring, the leader shoots and 50% of all lateral shoots of half of the investigated 5-year old Abies alba saplings were clipped to simulate browsing. At harvest, different fine-root classes were separated, and starch as an important storage compartment was analysed for concentrations. The phenology had a strong effect on the allocation of the 13C-label from shoots to roots. In spring, shoots did not supply the fine-roots with high amounts of the 13C-label, because the fine-roots contained less than 1% of the applied 13C. In summer and autumn, however, shoots allocated relatively high amounts of the 13C-label to the fine roots. The incorporation of the 13C-label as structural C or as starch into the roots is strongly dependent on the root type and the root diameter. In newly formed fine roots, 3-5% of the applied 13C was incorporated, whereas 1-3% in the ≤0.5 mm root class and 1-1.5% in the >0.5-1.0 mm root class were recorded. Highest 13C-enrichment in the starch was recorded in the newly formed fine roots in autumn. The clipping treatment had a significant positive effect on the amount of allocated 13C-label to the fine roots after the spring labelling, with high relative 13C-contents observed in the ≤0.5 mm and the >0.5-1.0 mm fine-root classes of clipped trees. No effects of the clipping were observed after summer and autumn labelling in the 13C-allocation patterns. Overall, our data imply that the season of C assimilation and, thus, the phenology of trees is the main determinant of the C allocation from shoots to roots and is clearly more important than browsing.

Fine root architecture of nine North American trees

Treesearch

Kurt S. Pregitzer; Jared L. DeForest; Andrew J. Burton; Michael F. Allen; Roger W. Ruess; Ronald L. Hendrick

2002-01-01

The fine roots of trees are concentrated on lateral branches that arise from perennial roots. They are important in the acquisition of water and essential nutrients, and at the ecosystem level, they make a significant contribution to biogeochemical cycling. Fine roots have often been studied according to arbitrary size classes, e.g., all roots less than 1 or 2 mm in...

Belowground effects of enhanced tropospheric ozone and drought in a beech/spruce forest (Fagus sylvatica L./Picea abies [L.] Karst).

PubMed

Nikolova, Petia S; Andersen, Christian P; Blaschke, Helmut; Matyssek, Rainer; Häberle, Karl-Heinz

2010-04-01

The effects of experimentally elevated O(3) on soil respiration rates, standing fine-root biomass, fine-root production and delta(13)C signature of newly produced fine roots were investigated in an adult European beech/Norway spruce forest in Germany during two subsequent years with contrasting rainfall patterns. During humid 2002, soil respiration rate was enhanced under elevated O(3) under beech and spruce, and was related to O(3)-stimulated fine-root production only in beech. During dry 2003, the stimulating effect of O(3) on soil respiration rate vanished under spruce, which was correlated with decreased fine-root production in spruce under drought, irrespective of the O(3) regime. delta(13)C signature of newly formed fine-roots was consistent with the differing g(s) of beech and spruce, and indicated stomatal limitation by O(3) in beech and by drought in spruce. Our study showed that drought can override the stimulating O(3) effects on fine-root dynamics and soil respiration in mature beech and spruce forests. 2009 Elsevier Ltd. All rights reserved.

Fine-root growth in a forested bog is seasonally dynamic, but shallowly distributed in nutrient-poor peat

DOE PAGES

Iversen, Colleen M.; Childs, Joanne; Norby, Richard J.; ...

2017-03-30

Fine roots contribute to ecosystem carbon, water, and nutrient fluxes through resource acquisition, respiration, exudation, and turnover, but are understudied in peatlands. Here, we aimed to determine how the amount and timing of fine-root growth in a forested, ombrotrophic bog varied across gradients of vegetation density, peat microtopography, and changes in environmental conditions across the growing season and throughout the peat profile. We quantified fine-root peak standing crop and growth using non-destructive minirhizotron technology over a two-year period, focusing on the dominant woody species in the bog: Picea mariana, Larix laricina, Rhododendron groenlandicum, and Chamaedaphne calyculata. The fine roots ofmore » trees and shrubs were concentrated in raised hummock microtopography, with more tree roots associated with greater tree densities and a unimodal peak in shrub roots at intermediate tree densities. Fine-root growth tended to be seasonally dynamic, but shallowly distributed, in a thin layer of nutrient-poor, aerobic peat above the growing season water table level. Finally, the dynamics and distribution of fine roots in this forested ombrotrophic bog varied across space and time in response to biological, edaphic, and climatic conditions, and we expect these relationships to be sensitive to projected environmental changes in northern peatlands.« less

Fine-root growth in a forested bog is seasonally dynamic, but shallowly distributed in nutrient-poor peat

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

Iversen, Colleen M.; Childs, Joanne; Norby, Richard J.

Fine roots contribute to ecosystem carbon, water, and nutrient fluxes through resource acquisition, respiration, exudation, and turnover, but are understudied in peatlands. Here, we aimed to determine how the amount and timing of fine-root growth in a forested, ombrotrophic bog varied across gradients of vegetation density, peat microtopography, and changes in environmental conditions across the growing season and throughout the peat profile. We quantified fine-root peak standing crop and growth using non-destructive minirhizotron technology over a two-year period, focusing on the dominant woody species in the bog: Picea mariana, Larix laricina, Rhododendron groenlandicum, and Chamaedaphne calyculata. The fine roots ofmore » trees and shrubs were concentrated in raised hummock microtopography, with more tree roots associated with greater tree densities and a unimodal peak in shrub roots at intermediate tree densities. Fine-root growth tended to be seasonally dynamic, but shallowly distributed, in a thin layer of nutrient-poor, aerobic peat above the growing season water table level. Finally, the dynamics and distribution of fine roots in this forested ombrotrophic bog varied across space and time in response to biological, edaphic, and climatic conditions, and we expect these relationships to be sensitive to projected environmental changes in northern peatlands.« less

Adaptive fine root foraging patterns in climate experiments and natural gradients

NASA Astrophysics Data System (ADS)

Ostonen, Ivika; Truu, Marika; Parts, Kaarin; Truu, Jaak

2017-04-01

Site based manipulative experiments and studies along climatic gradients have long been keystones of ecological research. We aimed to compare the response of ectomycorrhizal (EcM) and fine roots in manipulative studies and along climate gradient to describe the universal trends in root traits and to raise hypotheses about general mechanisms in fine root system adaptation of forest trees in global change. The root traits from two climate manipulation experiments - Bangor FACE and FAHM in Estonia, manipulated by CO2 concentration and relative air humidity in silver birch forest ecosystems, respectively and the data for three most ubiquitous tree species - Norway spruce (Picea abies), Scots pine (Pinus sylvestris) and silver birch (Betula pendula) stands along natural gradient encompassing different climate and forest zones in Northern Europe were analysed. There are two main strategies in response of fine root system of trees: A) an extensive increase in absorptive root biomass, surface area and length, or B) a greater reliance on root-associated EcM fungi and bacterial communities with a smaller investment to absorptive root biomass. Trees in all studies tended to increase the EcM root biomass and the proportion of EcM root biomass of total fine root biomass towards harsh (northern boreal forests) or changed conditions (stress created by the increase in CO2 concentration or relative air humidity). We envisage a role of trilateral relation between the morphological traits of absorptive fine roots, exploration types of colonising EcM fungi and rhizosphere and bulk soil bacterial community structure. A significant change in EcM absorptive fine root biomass in all experiments and for all studied tree species coincided with changes in absorptive root morphology, being longer and thinner root tips with higher root tissue density in poor/treated sites. These changes were associated with significant shifts in community structure of dominating EcM fungi as well as soil and rhizosphere bacterial communities. We suggest a multidimensional concept of absorptive fine root foraging strategies involving both qualitative and quantitative changes in root-mycorhizosphere along environmental gradients and in climate experiments.

Machine vision system for measuring conifer seedling morphology

NASA Astrophysics Data System (ADS)

Rigney, Michael P.; Kranzler, Glenn A.

1995-01-01

A PC-based machine vision system providing rapid measurement of bare-root tree seedling morphological features has been designed. The system uses backlighting and a 2048-pixel line- scan camera to acquire images with transverse resolutions as high as 0.05 mm for precise measurement of stem diameter. Individual seedlings are manually loaded on a conveyor belt and inspected by the vision system in less than 0.25 seconds. Designed for quality control and morphological data acquisition by nursery personnel, the system provides a user-friendly, menu-driven graphical interface. The system automatically locates the seedling root collar and measures stem diameter, shoot height, sturdiness ratio, root mass length, projected shoot and root area, shoot-root area ratio, and percent fine roots. Sample statistics are computed for each measured feature. Measurements for each seedling may be stored for later analysis. Feature measurements may be compared with multi-class quality criteria to determine sample quality or to perform multi-class sorting. Statistical summary and classification reports may be printed to facilitate the communication of quality concerns with grading personnel. Tests were conducted at a commercial forest nursery to evaluate measurement precision. Four quality control personnel measured root collar diameter, stem height, and root mass length on each of 200 conifer seedlings. The same seedlings were inspected four times by the machine vision system. Machine stem diameter measurement precision was four times greater than that of manual measurements. Machine and manual measurements had comparable precision for shoot height and root mass length.

Elevated CO2 or O3 effects on fine-root survivorship in ponderosa pine

EPA Science Inventory

Atmospheric carbon dioxide (CO2) and ozone (O3) concentrations are rising, which may have opposing effects on tree C balance and allocation to fine roots. More information is needed on interactive CO2 and O3 effects on roots, particularly fine-root life span, a critical demograp...

ELEVATED CO2 AND O3 EFFECTS ON FINE-ROOT SURVIVORSHIP IN PONDEROSA PINE MESOCOSMS

EPA Science Inventory

Atmospheric carbon dioxide (CO2) and ozone (O3) concentrations are rising, which may have opposing effects on tree C balance and allocation to fine roots. More information is needed on interactive CO2 and O3 effects on roots, particularly fine-root life span, a critical demograph...

Indirect quantification of fine root production in a near tropical wet mountainous region

NASA Astrophysics Data System (ADS)

Lu, X.; Zhang, J.; Huang, C.

2016-12-01

The main functions of fine root (defined as diameter <= 2 mm) are water and nutrient transports. Besides being a carbon (C) storage pool, it also provides a C flux pathway through soil and plant. Fine root takes up a small portion, normally 5%, of biomass in forest ecosystems, but 30% to 70% of total net primary production. Therefore, quantifying fine root productivity is important to study the forest C budget. Presumably, belowground growth can be indirectly estimated by the more accessible aboveground vegetation structure dynamics. To verify the relationship with fine root productivity, we take internal (floristic) and external (environmental) factors into account, including litter production, canopy density (leaf area index), leaf nutrients (N, K, Ca, Mg, P), weather and/or soil physical conditions (air temperature, humidity, precipitation, solar radiation and soil moisture). The study was conducted in near tropical broadleaf (700 m asl) and conifer (1700 m asl) forests in northeastern Taiwan, generally receiving more than 4000 mm of precipitation per year. For each site, 16 50-cm long minirhizotron tubes were installed. Fine root images were acquired every three weeks. Growth and decline, newly presence and absence of fine roots were delineated by image processing algorithms to derive fine-root productivity through time. Aforementioned internal and external attributes were simultaneously collected as well. Some of these variables were highly correlated and were detrended using principal component analysis. We found that these transformed variables (mainly associated with litter production, precipitation and solar radiation) can delineate the spatiotemporal dynamics of root production well (r2 = 0.87, p = 0.443). In conclusion, this study demonstrated the feasibility of utilized aboveground variables to indirectly assess fine root growth, which could be further developed for the regional scale mapping with aid of remote sensing.

Fine root dynamics in lodgepole pine and white spruce stands along productivity gradients in reclaimed oil sands sites.

PubMed

Jamro, Ghulam Murtaza; Chang, Scott X; Naeth, M Anne; Duan, Min; House, Jason

2015-10-01

Open-pit mining activities in the oil sands region of Alberta, Canada, create disturbed lands that, by law, must be reclaimed to a land capability equivalent to that existed before the disturbance. Re-establishment of forest cover will be affected by the production and turnover rate of fine roots. However, the relationship between fine root dynamics and tree growth has not been studied in reclaimed oil sands sites. Fine root properties (root length density, mean surface area, total root biomass, and rates of root production, turnover, and decomposition) were assessed from May to October 2011 and 2012 using sequential coring and ingrowth core methods in lodgepole pine (Pinus contorta Dougl.) and white spruce (Picea glauca (Moench.) Voss) stands. The pine and spruce stands were planted on peat mineral soil mix placed over tailings sand and overburden substrates, respectively, in reclaimed oil sands sites in Alberta. We selected stands that form a productivity gradient (low, medium, and high productivities) of each tree species based on differences in tree height and diameter at breast height (DBH) increments. In lodgepole pine stands, fine root length density and fine root production, and turnover rates were in the order of high > medium > low productivity sites and were positively correlated with tree height and DBH and negatively correlated with soil salinity (P < 0.05). In white spruce stands, fine root surface area was the only parameter that increased along the productivity gradient and was negatively correlated with soil compaction. In conclusion, fine root dynamics along the stand productivity gradients were closely linked to stand productivity and were affected by limiting soil properties related to the specific substrate used for reconstructing the reclaimed soil. Understanding the impact of soil properties on fine root dynamics and overall stand productivity will help improve land reclamation outcomes.

ADVANCING FINE ROOT RESEARCH WITH MINIRHIZOTRONS

EPA Science Inventory

Minirhizotrons provide a nondestructive, in situ method for directly viewing and studying fine roots. Although many insights into fine roots have been gained using minirhizotrons, it is clear from the literature that there is still wide variation in how minirhizotrons and minirhi...

Ground penetrating radar (GPR) detects fine roots of agricultural crops in the field

Treesearch

Xiuwei Liu; Xuejun Dong; Qingwu Xue; Daniel I. Leskovar; John Jifon; John R. Butnor; Thomas Marek

2018-01-01

Aim Ground penetrating radar (GPR) as a non-invasive technique is widely used in coarse root detection. However, the applicability of the technique to detect fine roots of agricultural crops is unknown. The objective of this study was to assess the feasibility of utilizing GPR to detect fine roots in the field.

Mechanical Failure of Fine Root Cortical Cells Initiates Plant Hydraulic Decline during Drought.

PubMed

Cuneo, Italo F; Knipfer, Thorsten; Brodersen, Craig R; McElrone, Andrew J

2016-11-01

Root systems perform the crucial task of absorbing water from the soil to meet the demands of a transpiring canopy. Roots are thought to operate like electrical fuses, which break when carrying an excessive load under conditions of drought stress. Yet the exact site and sequence of this dysfunction in roots remain elusive. Using in vivo x-ray computed microtomography, we found that drought-induced mechanical failure (i.e. lacunae formation) in fine root cortical cells is the initial and primary driver of reduced fine root hydraulic conductivity (Lp r ) under mild to moderate drought stress. Cortical lacunae started forming under mild drought stress (-0.6 MPa Ψ stem ), coincided with a dramatic reduction in Lp r , and preceded root shrinkage or significant xylem embolism. Only under increased drought stress was embolism formation observed in the root xylem, and it appeared first in the fine roots (50% loss of hydraulic conductivity [P 50 ] reached at -1.8 MPa) and then in older, coarse roots (P 50 = -3.5 MPa). These results suggest that cortical cells in fine roots function like hydraulic fuses that decouple plants from drying soil, thus preserving the hydraulic integrity of the plant's vascular system under early stages of drought stress. Cortical lacunae formation led to permanent structural damage of the root cortex and nonrecoverable Lp r , pointing to a role in fine root mortality and turnover under drought stress. © 2016 American Society of Plant Biologists. All Rights Reserved.

Drought effects on fine-root and ectomycorrhizal-root biomass in managed Pinus oaxacana Mirov stands in Oaxaca, Mexico.

PubMed

Valdés, María; Asbjornsen, Heidi; Gómez-Cárdenas, Martín; Juárez, Margarita; Vogt, Kristiina A

2006-03-01

The effects of a severe drought on fine-root and ectomycorrhizal biomass were investigated in a forest ecosystem dominated by Pinus oaxacana located in Oaxaca, Mexico. Root cores were collected during both the wet and dry seasons of 1998 and 1999 from three sites subjected to different forest management treatments in 1990 and assessed for total fine-root biomass and ectomycorrhizal-root biomass. Additionally, a bioassay experiment with P. oaxacana seedlings was conducted to assess the ectomycorrhizal inoculum potential of the soil for each of the three stands. Results indicated that biomasses of both fine roots and ectomycorrhizal roots were reduced by almost 60% in the drought year compared to the nondrought year. There were no significant differences in ectomycorrhizal and fine-root biomass between the wet and dry seasons. Further, the proportion of total root biomass consisting of ectomycorrhizal roots did not vary between years or seasons. These results suggest that both total fine-root biomass and ectomycorrhizal-root biomass are strongly affected by severe drought in these high-elevation tropical pine forests, and that these responses outweigh seasonal effects. Forest management practices in these tropical pine forests should consider the effects of drought on the capacity of P. oaxacana to maintain sufficient levels of ectomycorrhizae especially when there is a potential for synergistic interactions between multiple disturbances that may lead to more severe stress in the host plant and subsequent reductions in ectomycorrhizal colonization.

[Fine root biomass and production of four vegetation types in Loess Plateau, China].

PubMed

Deng, Qiang; Li, Ting; Yuan, Zhi-You; Jiao, Feng

2014-11-01

Fine roots (≤ 2 mm) play a major role in biogeochemical cycling in ecosystems. By the methods of soil cores and ingrowth soil cores, we studied the biomass and annual production of fine roots in 0-40 cm soil layers of four main vegetation types, i. e. , Robinia pseudoacacia plantation, deciduous shrubs, abandoned grassland, and Artemisia desertorum community in Loess Plateau, China. The spatial patterns of fine root biomass and production were negatively associated with latitudes. The fine root biomass in the 0-40 cm soil layer was in the order of deciduous shrubs (220 g · m(-2)), R. pseudoacacia plantation (163 g · m(-2)), abandoned grassland (162 g · m(-2)) and A. desertorum community (79 g · m(-2)). The proportion of ≤ 1 mm fine root biomass (74.1%) in the 0-40 cm soil layer of abandoned grassland was significantly higher than those in the other three vegetation types. The fine root biomass of the four vegetation types was mainly distributed in the 0-10 cm soil layer and decreased with soil depth. The proportion of fine root biomass (44.1%) in the 0-10 cm soil layer of abandoned grassland was significantly higher than those in other three vegetation types. The fine root productions of four vegetation types were in the order of abandoned grassland (315 g · m(-2) · a(-1)) > deciduous shrubs (249 g · m(-2) a(-1)) > R. pseudoacacia plantation (219 g · m(-2) · a(-1)) > A. desertorum community (115 g · m(-2) · a(-1)), and mainly concentrated in the 0-10 cm top soil layer and decreased with the soil depth. The proportion of the annual production (40.4%) in the 0-10 cm soil layer was the highest in abandoned grassland. Fine roots of abandoned grassland turned over faster than those from the other three vegetation types.

Effects of elevated CO2 on fine root dynamics in a Mojave Desert community: A FACE study

USGS Publications Warehouse

Phillips, D.L.; Johnson, M.G.; Tingey, D.T.; Catricala, C.E.; Hoyman, T.L.; Nowak, R.S.

2006-01-01

Fine roots (??? 1mm diameter) are critical in plant water and nutrient absorption, and it is important to understand how rising atmospheric CO2 will affect them as part of terrestrial ecosystem responses to global change. This study's objective was to determine effects of elevated CO2 on production, mortality, and standing crops of fine root length over 2 years in a free-air CO2 enrichment (FACE) facility in the Mojave Desert of southern Nevada, USA. Three replicate 25m diameter FACE rings were maintained at ambient (??? 370 ??mol mol-1) and elevated CO2 (??? 550 ??mol mol-1) atmospheric concentrations. Twenty-eight minirhizotron tubes were placed in each ring to sample three microsite locations: evergreen Larrea shrubs, drought-deciduous Ambrosia shrubs, and along systematic community transects (primarily in shrub interspaces which account for ??? 85% of the area). Seasonal dynamics were similar for ambient and elevated CO2: fine root production peaked in April-June, with peak standing crop occurring about 1 month later, and peak mortality occurring during the hot summer months, with higher values for all three measures in a wet year compared with a dry year. Fine root standing crop, production, and mortality were not significantly different between treatments except standing crop along community transects, where fine root length was significantly lower in elevated CO2. Fine root turnover (annual cumulative mortality/mean standing crop) ranged from 2.33 to 3.17 year-1, and was not significantly different among CO2 treatments, except for community transect tubes where it was significantly lower for elevated CO2. There were no differences in fine root responses to CO2 between evergreen (Larrea) and drought-deciduous (Ambrosia) shrubs. Combined with observations of increased leaf-level water-use efficiency and lack of soil moisture differences, these results suggest that under elevated CO2 conditions, reduced root systems (compared with ambient CO2) appear sufficient to provide resources for modest aboveground production increases across the community, but in more fertile shrub microsites, fine root systems of comparable size with those in ambient CO2 were required to support the greater aboveground production increases. For community transects, development of the difference in fine root standing crops occurred primarily through lower stimulation of fine root production in the elevated CO2 treatment during periods of high water availability. ?? 2005 Blackwell Publishing Ltd.

Building a better foundation: improving root-trait measurements to understand and model plant and ecosystem processes

DOE PAGES

McCormack, M. Luke; Guo, Dali; Iversen, Colleen M.; ...

2017-03-13

Trait-based approaches provide a useful framework to investigate plant strategies for resource acquisition, growth, and competition, as well as plant impacts on ecosystem processes. Despite significant progress capturing trait variation within and among stems and leaves, identification of trait syndromes within fine-root systems and between fine roots and other plant organs is limited. Here we discuss three underappreciated areas where focused measurements of fine-root traits can make significant contributions to ecosystem science. These include assessment of spatiotemporal variation in fine-root traits, integration of mycorrhizal fungi into fine-root-trait frameworks, and the need for improved scaling of traits measured on individual rootsmore » to ecosystem-level processes. Progress in each of these areas is providing opportunities to revisit how below-ground processes are represented in terrestrial biosphere models. Targeted measurements of fine-root traits with clear linkages to ecosystem processes and plant responses to environmental change are strongly needed to reduce empirical and model uncertainties. Further identifying how and when suites of root and whole-plant traits are coordinated or decoupled will ultimately provide a powerful tool for modeling plant form and function at local and global scales.« less

Building a better foundation: improving root-trait measurements to understand and model plant and ecosystem processes

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

McCormack, M. Luke; Guo, Dali; Iversen, Colleen M.

Trait-based approaches provide a useful framework to investigate plant strategies for resource acquisition, growth, and competition, as well as plant impacts on ecosystem processes. Despite significant progress capturing trait variation within and among stems and leaves, identification of trait syndromes within fine-root systems and between fine roots and other plant organs is limited. Here we discuss three underappreciated areas where focused measurements of fine-root traits can make significant contributions to ecosystem science. These include assessment of spatiotemporal variation in fine-root traits, integration of mycorrhizal fungi into fine-root-trait frameworks, and the need for improved scaling of traits measured on individual rootsmore » to ecosystem-level processes. Progress in each of these areas is providing opportunities to revisit how below-ground processes are represented in terrestrial biosphere models. Targeted measurements of fine-root traits with clear linkages to ecosystem processes and plant responses to environmental change are strongly needed to reduce empirical and model uncertainties. Further identifying how and when suites of root and whole-plant traits are coordinated or decoupled will ultimately provide a powerful tool for modeling plant form and function at local and global scales.« less

[Decomposition and nutrient release of root with different diameters of three subalpine dominant trees in western area of Sichuan Province, China].

PubMed

Tang, Shi-shan; Yang, Wan-qin; Wang, Hai-peng; Xiong, Li; Nie, Fu-yu; Xu, Shen-feng

2015-10-01

In this study, a buried bag experiment was used to investigate mass loss and C, N and P release patterns of fine (≤2 mm), medium (2-5 mm) and coarse (≥ 5 mm) roots of 3 subalpine dominant trees, i. e., Betula albosinensis, Abies faxoniana and Picea asperata in the growing and non-growing seasons. In general, the remaining mass of B. albosinensis was lower than that of A. faxoniana and P. asperata. In addition, root remaining mass increased with the increase of root diameter for the same species. The mass losing rate in the non-growing season was 52.1%-64.4% of a year. The C release of B. albosinensis was the highest, but that of A. faxoniana was the lowest. Also, C release decreased with the increase of root diameter. N of A. faxoniana and P. asperata were enriched in the non-growing season but released in the growing season. However, the opposite pattern was found for B. albosinensis. During the non-growing season, the amount of N enrichment increased with the increase of root diameter. The P release of 3 species was characterized as the enrichment-release pattern. P enrichment of A. faxoniana was significantly greater than that of P. asperata and B. albosinensis. Nevertheless, no significant difference was observed between diameter sizes. In conclusion, diameter size had significant effect on root decomposition in the subalpine forests of western Sichuan, and the diameter effect was dependent on tree species and season.

Limited Effects of Variable-Retention Harvesting on Fungal Communities Decomposing Fine Roots in Coastal Temperate Rainforests.

PubMed

Philpott, Timothy J; Barker, Jason S; Prescott, Cindy E; Grayston, Sue J

2018-02-01

Fine root litter is the principal source of carbon stored in forest soils and a dominant source of carbon for fungal decomposers. Differences in decomposer capacity between fungal species may be important determinants of fine-root decomposition rates. Variable-retention harvesting (VRH) provides refuge for ectomycorrhizal fungi, but its influence on fine-root decomposers is unknown, as are the effects of functional shifts in these fungal communities on carbon cycling. We compared fungal communities decomposing fine roots (in litter bags) under VRH, clear-cut, and uncut stands at two sites (6 and 13 years postharvest) and two decay stages (43 days and 1 year after burial) in Douglas fir forests in coastal British Columbia, Canada. Fungal species and guilds were identified from decomposed fine roots using high-throughput sequencing. Variable retention had short-term effects on β-diversity; harvest treatment modified the fungal community composition at the 6-year-postharvest site, but not at the 13-year-postharvest site. Ericoid and ectomycorrhizal guilds were not more abundant under VRH, but stand age significantly structured species composition. Guild composition varied by decay stage, with ruderal species later replaced by saprotrophs and ectomycorrhizae. Ectomycorrhizal abundance on decomposing fine roots may partially explain why fine roots typically decompose more slowly than surface litter. Our results indicate that stand age structures fine-root decomposers but that decay stage is more important in structuring the fungal community than shifts caused by harvesting. The rapid postharvest recovery of fungal communities decomposing fine roots suggests resiliency within this community, at least in these young regenerating stands in coastal British Columbia. IMPORTANCE Globally, fine roots are a dominant source of carbon in forest soils, yet the fungi that decompose this material and that drive the sequestration or respiration of this carbon remain largely uncharacterized. Fungi vary in their capacity to decompose plant litter, suggesting that fungal community composition is an important determinant of decomposition rates. Variable-retention harvesting is a forestry practice that modifies fungal communities by providing refuge for ectomycorrhizal fungi. We evaluated the effects of variable retention and clear-cut harvesting on fungal communities decomposing fine roots at two sites (6 and 13 years postharvest), at two decay stages (43 days and 1 year), and in uncut stands in temperate rainforests. Harvesting impacts on fungal community composition were detected only after 6 years after harvest. We suggest that fungal community composition may be an important factor that reduces fine-root decomposition rates relative to those of above-ground plant litter, which has important consequences for forest carbon cycling. Copyright © 2018 American Society for Microbiology.

High-Spatial and High-Mass Resolution Imaging of Surface Metabolites of Arabidopsis thaliana by Laser Desorption-Ionization Mass Spectrometry Using Colloidal Silver

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

Jun, Ji Hyun; Song, Zhihong; Liu, Zhenjiu

High-spatial resolution and high-mass resolution techniques are developed and adopted for the mass spectrometric imaging of epicuticular lipids on the surface of Arabidopsis thaliana. Single cell level spatial resolution of {approx}12 {micro}m was achieved by reducing the laser beam size by using an optical fiber with 25 {micro}m core diameter in a vacuum matrix-assisted laser desorption ionization-linear ion trap (vMALDI-LTQ) mass spectrometer and improved matrix application using an oscillating capillary nebulizer. Fine chemical images of a whole flower were visualized in this high spatial resolution showing substructure of an anther and single pollen grains at the stigma and anthers. Themore » LTQ-Orbitrap with a MALDI ion source was adopted to achieve MS imaging in high mass resolution. Specifically, isobaric silver ion adducts of C29 alkane (m/z 515.3741) and C28 aldehyde (m/z 515.3377), indistinguishable in low-resolution LTQ, can now be clearly distinguished and their chemical images could be separately constructed. In the application to roots, the high spatial resolution allowed molecular MS imaging of secondary roots and the high mass resolution allowed direct identification of lipid metabolites on root surfaces.« less

Carbon cycling in fine roots of several mature forests: results using either locally-derived or bomb-derived radiocarbon enrichment

NASA Astrophysics Data System (ADS)

Gaudinski, J. B.; Riley, W. J.; Torn, M. S.; Dawson, T. E.; Trumbore, S. E.; Joslin, J. D.; Majdi, H.; Hanson, P. J.; Swanston, C.

2008-12-01

This work seeks to improve our ability to quantify C cycling rates in fine roots of trees in mature deciduous and coniferous forests. We use two different types of atmospheric 14CO2 enrichment to trace the time elapsed since C in plant tissues was fixed from the atmosphere by photosynthesis. The first uses a local enrichment of 14CO2 which occurred in early summer 1999, at the Oak Ridge Reservation, Tennessee. The second, employed at three different sites, uses the global enrichment in background atmospheric 14CO2 caused by thermonuclear weapons testing (bomb-14C). In both cases we employ a new model (Radix1.0) to track C and 14C fluxes through fine root populations. Radix simulates two live-root populations (the longer-lived one having structural and non-structural C components), two dead-root pools, non-normally distributed root mortality turnover times, a stored C pool, seasonal growth and respiration patterns, a best-fit to measurements approach to estimate model parameters, and Monte Carlo uncertainty analysis. Our results show that: (1) New fine-root growth contains a lot of stored C (~55%) but it is young in age (0.7 y). (2) The effect of stored reserves on estimated ages of fine roots is unlikely to be large in most natural abundance isotope studies. However, models should take stored reserves into account, particularly for pulse labeling studies and fast-cycling roots (< 1 y). (3) Radiocarbon values show a stronger correlation with position on the root branch system than they do with diameter or depth in the soil profile. (4) Live fine root dynamics are well described by a short-lived and a long-lived population, with mean turnover times <1 y and ~12 y, respectively. (5) Dead root decomposition is best modeled with (at least) two pools, with moderate (~2 y) and slow (~10 y) decomposition turnover times. (6) Root respiration has a large effect on fine root biomass and isotopic composition, and should be included in ecosystem C and isotope models. (7) It is important to distinguish structural from non-structural components in the long-lived root pool. Otherwise the 14C signature of root respiration is significantly different than atmospheric. We conclude that realistic quantification of C flows through fine roots requires a model with a level of complexity similar to Radix. Moreover, future root research efforts should seek to sample and sort roots by position on the root branch system rather than by diameter size class and improve estimates of root respiration within fine root populations.

Fine Root Productivity and Turnover of Ectomycorrhizal and Arbuscular Mycorrhizal Tree Species in a Temperate Broad-Leaved Mixed Forest

PubMed Central

Kubisch, Petra; Hertel, Dietrich; Leuschner, Christoph

2016-01-01

Advancing our understanding of tree fine root dynamics is of high importance for tree physiology and forest biogeochemistry. In temperate broad-leaved forests, ectomycorrhizal (EM) and arbuscular mycorrhizal (AM) tree species often are coexisting. It is not known whether EM and AM trees differ systematically in fine root dynamics and belowground resource foraging strategies. We measured fine root productivity (FRP) and fine root turnover (and its inverse, root longevity) of three EM and three AM broad-leaved tree species in a natural cool-temperate mixed forest using ingrowth cores and combined the productivity data with data on root biomass per root orders. FRP and root turnover were related to root morphological traits and aboveground productivity. FRP differed up to twofold among the six coexisting species with larger species differences in lower horizons than in the topsoil. Root turnover varied up to fivefold among the species with lowest values in Acer pseudoplatanus and highest in its congener Acer platanoides. Variation in root turnover was larger within the two groups than between EM and AM species. We conclude that the main determinant of FRP and turnover in this mixed forest is species identity, while the influence of mycorrhiza type seems to be less important. PMID:27617016

Adaptive root foraging strategies along a boreal-temperate forest gradient.

PubMed

Ostonen, Ivika; Truu, Marika; Helmisaari, Heljä-Sisko; Lukac, Martin; Borken, Werner; Vanguelova, Elena; Godbold, Douglas L; Lõhmus, Krista; Zang, Ulrich; Tedersoo, Leho; Preem, Jens-Konrad; Rosenvald, Katrin; Aosaar, Jürgen; Armolaitis, Kęstutis; Frey, Jane; Kabral, Naima; Kukumägi, Mai; Leppälammi-Kujansuu, Jaana; Lindroos, Antti-Jussi; Merilä, Päivi; Napa, Ülle; Nöjd, Pekka; Parts, Kaarin; Uri, Veiko; Varik, Mats; Truu, Jaak

2017-08-01

The tree root-mycorhizosphere plays a key role in resource uptake, but also in the adaptation of forests to changing environments. The adaptive foraging mechanisms of ectomycorrhizal (EcM) and fine roots of Picea abies, Pinus sylvestris and Betula pendula were evaluated along a gradient from temperate to subarctic boreal forest (38 sites between latitudes 48°N and 69°N) in Europe. Variables describing tree resource uptake structures and processes (absorptive fine root biomass and morphology, nitrogen (N) concentration in absorptive roots, extramatrical mycelium (EMM) biomass, community structure of root-associated EcM fungi, soil and rhizosphere bacteria) were used to analyse relationships between root system functional traits and climate, soil and stand characteristics. Absorptive fine root biomass per stand basal area increased significantly from temperate to boreal forests, coinciding with longer and thinner root tips with higher tissue density, smaller EMM biomass per root length and a shift in soil microbial community structure. The soil carbon (C) : N ratio was found to explain most of the variability in absorptive fine root and EMM biomass, root tissue density, N concentration and rhizosphere bacterial community structure. We suggest a concept of absorptive fine root foraging strategies involving both qualitative and quantitative changes in the root-mycorrhiza-bacteria continuum along climate and soil C : N gradients. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

RELATING FINE ROOT BIOMASS TO SOIL AND CLIMATE CONDITIONS IN THE PACIFIC NORTHWEST

EPA Science Inventory

The additive contribution of fine root biomass for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) and western hemlock (Tsuga heterophylla (Raf.) Sarg.) to the stand average fine root biomass were estimated for eight conifer stands in the Pacific Northwest. Base...

Fine Root Growth Phenology, Production, and Turnover in a Northern Hardwood Forest Ecosystem

Treesearch

Dudley J. Raynal

1994-01-01

A large part of the nutrient flux in deciduous forests is through fine root turnover, yet this process is seldom measured. As part of a nutrient cycling study, fine root dynamics were studied for two years at Huntington Forest in the Adirondack Mountain region of New York, USA. Root growth phenology was characterized using field rhizotrons, three methods were used to...

Aluminum and calcium in fine root tips of red spruce collected from the forest floor

Treesearch

K.T. Smith; W.C. Shortle; W.D. Ostrofsky

1995-01-01

Root chemistry is being increasingly used as a marker of biologically relevant soil chemistry. To evaluate this marker, we determined the precision of measurement, the effect of organic soil horizon, and the effect of stand elevation on the chemistry of fine root tips of red spruce (Picea rubens Sarg.) Fine root tips were collected from the F and H...

The effect of increased air humidity on fine root and rhizome biomass and turnover of silver birch forest ecosystem - a FAHM study.

NASA Astrophysics Data System (ADS)

Ostonen, I.; Kupper, P.; Sõber, J.; Aosaar, J.; Varik, M.; Lõhmus, K.

2012-04-01

A facility for free air humidity manipulation (FAHM) was established to investigate the effect of increased air humidity on belowground biomass and turnover in silver birch (Betula pendula Roth.) forest ecosystems with respect to rising air humidity predicted for Northern Europe. Fine root and rhizomes are short-lived and recognized as the most important component contributing to below-ground C fluxes in forests. The FAHM system enables air relative humidity to be increased on average 7 units (%) over the ambient level during mist fumigation. The experimental site contains humidified (H) and control (C) plots; each plot contains sectors with diverse "forest" understory and early successional grasses. The trees were planted in 2006, humidification started in spring 2008, and soil cores to study fine root and rhizome biomass and turnover were taken in 2007, 2009 and 2010. In July 2009, total fine root and rhizome biomass was 8 tons per ha in C and 16 tons per ha in H plots. The roots of understory formed 86% in C and 93% H plots, respectively. Our preliminary data suggest that the increased humidity affected more the roots of understory plants: fine root and rhizome biomass and production increased approximately twice by increasing air humidity. However, the tendency was similar for fine root biomass and production of silver birch. Fine root turnover speeded up for both silver birch and understory roots in H plots. Hence, changes in air humidity can significantly affect forest carbon cycling.

Unresolving the "real age" of fine roots in forest ecosystems

NASA Astrophysics Data System (ADS)

Solly, Emily; Brunner, Ivano; Herzog, Claude; Schöning, Ingo; Schrumpf, Marion; Schweigruber, Fritz; Trumbore, Susan; Hagedorn, Frank

2016-04-01

Estimating the turnover time of tree fine roots is crucial for modelling soil organic matter dynamics, but it is one of the biggest challenges in soil ecology and one of the least understood aspects of the belowground carbon cycle. The methods used - ranging from radiocarbon to ingrowth cores and root cameras (minirhizotrons) - yield very diverse pictures of fine root dynamics in forest ecosystems with turnover rates reaching from less than one year to decades. These have huge implications on estimates of carbon allocation to root growth and maintenance and on the persistence of root carbon in soils before it is decomposed or leached. We will present a new approach, involving techniques to study plant anatomy, which unravels the "real age" of fine roots. For a range of forests with diverse water and nutrient limitations located at different latitudes, we investigated the annual growth rings in the secondary xylem of thin transversal sections of fine roots belonging to tree species which form distinct growth rings. In temperate forests we find mean root "ring ages" of 1-2 years while in sub-arctic forests living fine roots can also persist for several years. The robustness of these results were tested by counting the maximum yearly growth rings in tree seedlings of known age and by counting the maximum number of growth rings of fine roots grown in ingrowth cores which were kept in temperate forest soils for one and two years. Radiocarbon estimates of mean "carbon ages", which define the time elapsed since structural carbon was fixed from the atmosphere, instead average around a decade in root systems of temperate forests (mixture of newly produced and older living roots). This dramatic difference may not be related to methodological bias, but to a time lag between C assimilation and production of a portion of fine root tissues due to the storage of older carbon components. The time lag depends very likely on tree species and environmental conditions. We further observed that the root ring age increases with root diameter although it does not appear to be related to the branching order. Our findings suggest that both the physiological and radiocarbon ages must be modelled jointly in forest ecosystems, if we want to correctly account for the inputs of root litter

A SPATIAL ANALYSIS OF FINE-ROOT BIOMASS FROM STAND DATA IN OREGON AND WASHINGTON

EPA Science Inventory

Because of the high spatial variability of fine roots in natural forest stands, accurate estimates of stand-level fine root biomass are difficult and expensive to obtain by standard coring methods. This study compares two different approaches that employ aboveground tree metrics...

A SPATIAL ANALYSIS OF THE FINE ROOT BIOMASS FROM STAND DATA IN THE PACIFIC NORTHWEST

EPA Science Inventory

High spatial variability of fine roots in natural forest stands makes accurate estimates of stand-level fine root biomass difficult and expensive to obtain by standard coring methods. This study uses aboveground tree metrics and spatial relationships to improve core-based estima...

ELEVATED CO2 AND ELEVATED TEMPERATURE HAVE NO EFFECT ON DOUGLAS-FIR FINE-ROOT DYNAMICS IN NITROGEN-POOR SOIL

EPA Science Inventory

Here, we investigate fine-root production, mortality and standing crop of Douglas-fir (Pseudotsuga menziesii) seedlings exposed to elevated atmospheric CO2 and elevated air temperature. We hypothesized that these treatments would increase fine-root production, but that mortality ...

A global exploration of fine-root trait variation: opening the black box

USDA-ARS?s Scientific Manuscript database

A major part of ecosystem functioning relies on processes below ground, which are governed by fine root traits. This study synthesizes published and unpublished fine-root trait data available worldwide (>9000 observations from >1100 species on 14 traits) and examines their ecological value and globa...

Space sequestration below ground in old-growth spruce-beech forests-signs for facilitation?

PubMed

Bolte, Andreas; Kampf, Friederike; Hilbrig, Lutz

2013-01-01

Scientists are currently debating the effects of mixing tree species for the complementary resource acquisition in forest ecosystems. In four unmanaged old-growth spruce-beech forests in strict nature reserves in southern Sweden and northern Germany we assessed forest structure and fine rooting profiles and traits (≤2 mm) by fine root sampling and the analysis of fine root morphology and biomass. These studies were conducted in selected tree groups with four different interspecific competition perspectives: (1) spruce as a central tree, (2) spruce as competitor, (3) beech as a central tree, and (4) beech as competitor. Mean values of life fine root attributes like biomass (FRB), length (FRL), and root area index (RAI) were significantly lower for spruce than for beech in mixed stands. Vertical profiles of fine root attributes adjusted to one unit of basal area (BA) exhibited partial root system stratification when central beech is growing with spruce competitors. In this constellation, beech was able to raise its specific root length (SRL) and therefore soil exploration efficiency in the subsoil, while increasing root biomass partitioning into deeper soil layers. According to relative values of fine root attributes (rFRA), asymmetric below-ground competition was observed favoring beech over spruce, in particular when central beech trees are admixed with spruce competitors. We conclude that beech fine rooting is facilitated in the presence of spruce by lowering competitive pressure compared to intraspecific competition whereas the competitive pressure for spruce is increased by beech admixture. Our findings underline the need of spatially differentiated approaches to assess interspecific competition below ground. Single-tree approaches and simulations of below-ground competition are required to focus rather on microsites populated by tree specimens as the basic spatial study area.

Space sequestration below ground in old-growth spruce-beech forests—signs for facilitation?

PubMed Central

Bolte, Andreas; Kampf, Friederike; Hilbrig, Lutz

2013-01-01

Scientists are currently debating the effects of mixing tree species for the complementary resource acquisition in forest ecosystems. In four unmanaged old-growth spruce-beech forests in strict nature reserves in southern Sweden and northern Germany we assessed forest structure and fine rooting profiles and traits (≤2 mm) by fine root sampling and the analysis of fine root morphology and biomass. These studies were conducted in selected tree groups with four different interspecific competition perspectives: (1) spruce as a central tree, (2) spruce as competitor, (3) beech as a central tree, and (4) beech as competitor. Mean values of life fine root attributes like biomass (FRB), length (FRL), and root area index (RAI) were significantly lower for spruce than for beech in mixed stands. Vertical profiles of fine root attributes adjusted to one unit of basal area (BA) exhibited partial root system stratification when central beech is growing with spruce competitors. In this constellation, beech was able to raise its specific root length (SRL) and therefore soil exploration efficiency in the subsoil, while increasing root biomass partitioning into deeper soil layers. According to relative values of fine root attributes (rFRA), asymmetric below-ground competition was observed favoring beech over spruce, in particular when central beech trees are admixed with spruce competitors. We conclude that beech fine rooting is facilitated in the presence of spruce by lowering competitive pressure compared to intraspecific competition whereas the competitive pressure for spruce is increased by beech admixture. Our findings underline the need of spatially differentiated approaches to assess interspecific competition below ground. Single-tree approaches and simulations of below-ground competition are required to focus rather on microsites populated by tree specimens as the basic spatial study area. PMID:24009616

Relationship between fine-root exudation and respiration of two Quercus species in a Japanese temperate forest.

PubMed

Sun, Lijuan; Ataka, Mioko; Kominami, Yuji; Yoshimura, Kenichi

2017-08-01

Plants allocate a considerable amount of carbon (C) to fine roots as respiration and exudation. Fine-root exudation could stimulate microbial activity, which further contributes to soil heterotrophic respiration. Although both root respiration and exudation are important components of belowground C cycling, how they relate to each other is less well known. In this study, we aimed to explore this relationship on mature trees growing in the field. The measurements were performed on two canopy species, Quercus serrata Thunb. and Quercus glauca, in a warm temperate forest. The respiration and exudation rates of the same fine-root segment were measured in parallel with a syringe-basis incubation and a closed static chamber, respectively. We also measured root traits and ectomycorrhizal colonization ratio because these indexes commonly relate to root respiration and reflect root physiology. The microbial activity enhanced by root exudation was investigated by comparing the dissolved organic carbon (DOC) and microbial biomass carbon (MBC) between rhizosphere soils and bulk soils. Mean DOC concentration and MBC were ca two times higher in the rhizosphere soils and positively related to exudation rates, indicating that exudation further relates to the C dynamics in the soils. Flux rates of exudation and respiration were positively correlated with each other. Both root exudation and respiration rates positively related to ectomycorrhizal colonization and root tissue nitrogen, and therefore the relationship between the two fluxes may be attributed to fine-root activity. The flux rates of root respiration were 8.7 and 10.5 times as much as those of exudation on a root-length basis and a root-weight basis, respectively. In spite of the fact that flux rates of respiration and exudation varied enormously among the fine-root segments of the two Quercus species, exudation was in proportion to respiration. This result gives new insight into the fine-root C-allocation strategy and the belowground C dynamics. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Fine root dynamics in moso bamboo and Japanese cedar forest by scanner method in central Taiwan

NASA Astrophysics Data System (ADS)

Chen, Zhi-Wei; Lin, Po-Hsuan; Kume, Tomonori

2017-04-01

Phyllostachys pubescens is one of the most important economic plant in the world. Phyllostachys pubescens originates from China and it had been introduced to neighbor countries about three hundred ago due to its economic value. But substantial bamboo forests were abandoned due to declines in demand. These unmanaged bamboo forests have been expanding to adjacent original forests in northern Taiwan. This vegetation alternation may not only decrease the local biodiversity but also affect the carbon cycle. Fine roots are responsible for water and nutrients acquisition and forming the most active part of the whole root system. The characteristics of fine roots are non-woody, small diameter and short lifespan. When roots keep producing new roots and replacing old roots, carbon and nutrients was transported into soil. Consequently, fine root production is one of the important component to understand the below-ground carbon cycle. However, there is few studies about fine root production in moso bamboo forests. We still lack effective method to obtain quantitative and objective data in Taiwan. It severely limits us to understand the below-ground carbon dynamics there. Minirhizotrons method has been used to investigate fine root dynamics by inserting transparent tubes into soil and by comparing changes in root length in images taken by micro-camera. But this method has some shortcomings; i.e. Most of image analysis are conducted manually and time-consuming. And it is difficult to estimate the stand level fine root production from small observation view. A new method "scanner method", which collect A4-size image (bigger than minirhizotrons) can overcome some parts of the shortcoming of minirhizotrons. The transparent acrylic box with A4-box view is inserted into soil and the interface between soil and box is scanned by commercial scanner. We can monitor the total projected root area, growth and decomposition separately by series of images. The primary objective of this study is to characterize the temporal and spatial variation of fine root dynamics in moso bamboo forests in central Taiwan by using scanner method with 6 acrylic boxes. Other the other hand, this study compared the result with those of adjacent Japanese cedar forests with 8 acrylic boxes. Consequently, we found the fine root production rate and decomposition rate of the bamboo forest are higher than cedar forest. Also, the timing of first observation of new roots was earlier in bamboo forest than cedar forest. This study also examined differences of temporal patterns among measurement locations based on long-term data after box installation.

Nutrient limitation in three lowland tropical forests in southern China receiving high nitrogen deposition: insights from fine root responses to nutrient additions.

PubMed

Zhu, Feifei; Yoh, Muneoki; Gilliam, Frank S; Lu, Xiankai; Mo, Jiangming

2013-01-01

Elevated nitrogen (N) deposition to tropical forests may accelerate ecosystem phosphorus (P) limitation. This study examined responses of fine root biomass, nutrient concentrations, and acid phosphatase activity (APA) of bulk soil to five years of N and P additions in one old-growth and two younger lowland tropical forests in southern China. The old-growth forest had higher N capital than the two younger forests from long-term N accumulation. From February 2007 to July 2012, four experimental treatments were established at the following levels: Control, N-addition (150 kg N ha(-1) yr(-1)), P-addition (150 kg P ha(-1) yr(-1)) and N+P-addition (150 kg N ha(-1) yr(-1) plus 150 kg P ha(-1) yr(-1)). We hypothesized that fine root growth in the N-rich old-growth forest would be limited by P availability, and in the two younger forests would primarily respond to N additions due to large plant N demand. Results showed that five years of N addition significantly decreased live fine root biomass only in the old-growth forest (by 31%), but significantly elevated dead fine root biomass in all the three forests (by 64% to 101%), causing decreased live fine root proportion in the old-growth and the pine forests. P addition significantly increased live fine root biomass in all three forests (by 20% to 76%). The combined N and P treatment significantly increased live fine root biomass in the two younger forests but not in the old-growth forest. These results suggest that fine root growth in all three study forests appeared to be P-limited. This was further confirmed by current status of fine root N:P ratios, APA in bulk soil, and their responses to N and P treatments. Moreover, N addition significantly increased APA only in the old-growth forest, consistent with the conclusion that the old-growth forest was more P-limited than the younger forests.

Rooting strategies in a subtropical savanna: a landscape-scale three-dimensional assessment.

PubMed

Zhou, Yong; Boutton, Thomas W; Wu, X Ben; Wright, Cynthia L; Dion, Anais L

2018-04-01

In resource-limited savannas, the distribution and abundance of fine roots play an important role in acquiring essential resources and structuring vegetation patterns and dynamics. However, little is known regarding the three-dimensional distribution of fine roots in savanna ecosystems at the landscape scale. We quantified spatial patterns of fine root density to a depth of 1.2 m in a subtropical savanna landscape using spatially specific sampling. Kriged maps revealed that fine root density was highest at the centers of woody patches, decreased towards the canopy edges, and reached lowest values within the grassland matrix throughout the entire soil profile. Lacunarity analyses indicated that spatial heterogeneities of fine root density decreased continuously to a depth of 50 cm and then increased in deeper portions of the soil profile across this landscape. This vertical pattern might be related to inherent differences in root distribution between trees/shrubs and herbaceous species, and the presence/absence of an argillic horizon across this landscape. The greater density of fine roots beneath woody patches in both upper and lower portions of the soil profile suggests an ability to acquire disproportionately more resources than herbaceous species, which may facilitate the development and persistence of woody patches across this landscape.

Overestimation of Crop Root Biomass in Field Experiments Due to Extraneous Organic Matter.

PubMed

Hirte, Juliane; Leifeld, Jens; Abiven, Samuel; Oberholzer, Hans-Rudolf; Hammelehle, Andreas; Mayer, Jochen

2017-01-01

Root biomass is one of the most relevant root parameters for studies of plant response to environmental change, soil carbon modeling or estimations of soil carbon sequestration. A major source of error in root biomass quantification of agricultural crops in the field is the presence of extraneous organic matter in soil: dead roots from previous crops, weed roots, incorporated above ground plant residues and organic soil amendments, or remnants of soil fauna. Using the isotopic difference between recent maize root biomass and predominantly C3-derived extraneous organic matter, we determined the proportions of maize root biomass carbon of total carbon in root samples from the Swiss long-term field trial "DOK." We additionally evaluated the effects of agricultural management (bio-organic and conventional), sampling depth (0-0.25, 0.25-0.5, 0.5-0.75 m) and position (within and between maize rows), and root size class (coarse and fine roots) as defined by sieve mesh size (2 and 0.5 mm) on those proportions, and quantified the success rate of manual exclusion of extraneous organic matter from root samples. Only 60% of the root mass that we retrieved from field soil cores was actual maize root biomass from the current season. While the proportions of maize root biomass carbon were not affected by agricultural management, they increased consistently with soil depth, were higher within than between maize rows, and were higher in coarse (>2 mm) than in fine (≤2 and >0.5) root samples. The success rate of manual exclusion of extraneous organic matter from root samples was related to agricultural management and, at best, about 60%. We assume that the composition of extraneous organic matter is strongly influenced by agricultural management and soil depth and governs the effect size of the investigated factors. Extraneous organic matter may result in severe overestimation of recovered root biomass and has, therefore, large implications for soil carbon modeling and estimations of the climate change mitigation potential of soils.

Dynamics of soil exploration by fine roots down to a depth of 10 m throughout the entire rotation in Eucalyptus grandis plantations

PubMed Central

Laclau, Jean-Paul; da Silva, Eder A.; Rodrigues Lambais, George; Bernoux, Martial; le Maire, Guerric; Stape, José L.; Bouillet, Jean-Pierre; Gonçalves, José L. de Moraes; Jourdan, Christophe; Nouvellon, Yann

2013-01-01

Although highly weathered soils cover considerable areas in tropical regions, little is known about exploration by roots in deep soil layers. Intensively managed Eucalyptus plantations are simple forest ecosystems that can provide an insight into the belowground growth strategy of fast-growing tropical trees. Fast exploration of deep soil layers by eucalypt fine roots may contribute to achieving a gross primary production that is among the highest in the world for forests. Soil exploration by fine roots down to a depth of 10 m was studied throughout the complete cycle in Eucalyptus grandis plantations managed in short rotation. Intersects of fine roots, less than 1 mm in diameter, and medium-sized roots, 1–3 mm in diameter, were counted on trench walls in a chronosequence of 1-, 2-, 3.5-, and 6-year-old plantations on a sandy soil, as well as in an adjacent 6-year-old stand growing in a clayey soil. Two soil profiles were studied down to a depth of 10 m in each stand (down to 6 m at ages 1 and 2 years) and 4 soil profiles down to 1.5–3.0 m deep. The root intersects were counted on 224 m2 of trench walls in 15 pits. Monitoring the soil water content showed that, after clear-cutting, almost all the available water stored down to a depth of 7 m was taken up by tree roots within 1.1 year of planting. The soil space was explored intensively by fine roots down to a depth of 3 m from 1 year after planting, with an increase in anisotropy in the upper layers throughout the rotation. About 60% of fine root intersects were found at a depth of more than 1 m, irrespective of stand age. The root distribution was isotropic in deep soil layers and kriged maps showed fine root clumping. A considerable volume of soil was explored by fine roots in eucalypt plantations on deep tropical soils, which might prevent water and nutrient losses by deep drainage after canopy closure and contribute to maximizing resource uses. PMID:23847645

Can increased nitrogen uptake at elevated CO2 be explained by an hypothesis of optimal root function?

NASA Astrophysics Data System (ADS)

McMurtrie, R. E.; Norby, R. J.; Näsholm, T.; Iversen, C.; Dewar, R. C.; Medlyn, B. E.

2011-12-01

Forest free-air CO2 enrichment (FACE) experiments have shown that annual nitrogen (N) uptake increases when trees are grown at elevated CO2 (eCO2) and that increased N uptake is critical for a sustained growth response to eCO2. Processes contributing to increased N uptake at eCO2 may include: accelerated decomposition of soil organic matter due to enhanced root carbon (C) exudation (so-called rhizosphere priming); increased C allocation to fine roots and increased root production at depth, both of which enhance N acquisition; differences in soil N availability with depth; changes in the abundance of N in chemical forms with differing mobility in soil; and reduced N concentrations, reduced maintenance respiration rates, and increased longevities of deeper roots. These processes have been synthesised in a model of annual N uptake in relation to the spatial distribution of roots. We hypothesise that fine roots are distributed spatially in order to maximise annual N uptake. The optimisation hypothesis leads to equations for the optimal vertical distribution of root biomass in relation to the distribution of available soil N and for maximum annual N uptake. We show how maximum N uptake and rooting depth are related to total root mass, and compare the optimal solution with an empirical function that has been fitted to root-distribution data from all terrestrial biomes. Finally, the model is used to explore the consequences of rhizosphere priming at eCO2 as observed at the Duke forest FACE experiment (Drake et al. 2011, Ecology Letters 14: 349-357) and of increasing N limitation over time as observed at the Oak Ridge FACE experiment (Norby et al. 2010, Proc. Nat. Acad. Sci. USA 107: 19368-19373).

[Effects of tree species fine root decomposition on soil active organic carbon].

PubMed

Liu, Yan; Wang, Si-Long; Wang, Xiao-Wei; Yu, Xiao-Jun; Yang, Yue-Jun

2007-03-01

With incubation test, this paper studied the effects of fine root decomposition of Alnus cremastogyne, Cunninghamia lanceolata and Michelia macclurei on the content of soil active organic carbon at 9 degrees C , 14 degrees C , 24 degrees C and 28 degrees C. The results showed that the decomposition rate of fine root differed significantly with test tree species, which was decreased in the order of M. macclurei > A. cremastogyne > C. lanceolata. The decomposition rate was increased with increasing temperature, but declined with prolonged incubation time. Fine root source, incubation temperature, and incubation time all affected the contents of soil microbial biomass carbon and water-soluble organic carbon. The decomposition of fine root increased soil microbial biomass carbon and water-soluble organic carbon significantly, and the effect decreased in the order of M. macclurei > A. cremastogyne > C. lanceolata. Higher contents of soil microbial biomass carbon and water-soluble organic carbon were observed at medium temperature and middle incubation stage. Fine root decomposition had less effect on the content of soil readily oxidized organic carbon.

Polyphenols in the woody roots of Norway spruce and European beech reduce TTC.

PubMed

Richter, Anika K; Frossard, Emmanuel; Brunner, Ivano

2007-01-01

A common method to determine the vitality of fine root tissue is the measurement of respiratory activity with triphenyltetrazolium chloride (TTC). The colorless TTC is reduced to the red-colored triphenyl formazan (TF) as a result of the dehydrogenase activity of the mitochondrial respiratory chain. However, measurements with woody fine roots of adult Norway spruce and European beech trees showed that dead control roots had a high potential to react with TTC. High reactivity was found in boiled fine roots and the bark of coarse roots, but not in the boiled wood of coarse roots. By sequential extraction of dried and ground adult Norway spruce fine roots, reactivity with TTC was reduced by about 75% (water extraction), 93% (water/methanol extraction) and 94% (water/acetone extraction). The water extract reacted with TTC in the same way as polyphenols such as lignin, catechin and epicatechin. Boiling did not affect the extent to which fine roots of adult trees reduced TTC, whereas it greatly reduced TTC reduction by seedling roots. Application of the TTC test to roots of spruce seedlings subjected to increasing drought showed a progressive decrease in TTC reduction. The decrease in TTC reduction was paralleled by a reduction in O(2) consumption, thus supporting the conclusion that for roots with a low polyphenol content the TTC test provides a valid assessment of tissue vitality. Our results suggest, however, that the TTC test should not be applied to the fine roots of adult trees because of their high content of polyphenolic compounds whose reaction with TTC masks changes in TTC reduction due to changes in the respiratory capacity of the tissue.

Tree species diversity interacts with elevated CO2 to induce a greater root system response.

PubMed

Smith, Andrew R; Lukac, Martin; Bambrick, Michael; Miglietta, Franco; Godbold, Douglas L

2013-01-01

As a consequence of land-use change and the burning of fossil fuels, atmospheric concentrations of CO2 are increasing and altering the dynamics of the carbon cycle in forest ecosystems. In a number of studies using single tree species, fine root biomass has been shown to be strongly increased by elevated CO2 . However, natural forests are often intimate mixtures of a number of co-occurring species. To investigate the interaction between tree mixture and elevated CO2 , Alnus glutinosa, Betula pendula and Fagus sylvatica were planted in areas of single species and a three species polyculture in a free-air CO2 enrichment study (BangorFACE). The trees were exposed to ambient or elevated CO2 (580 μmol mol(-1) ) for 4 years. Fine and coarse root biomass, together with fine root turnover and fine root morphological characteristics were measured. Fine root biomass and morphology responded differentially to the elevated CO2 at different soil depths in the three species when grown in monocultures. In polyculture, a greater response to elevated CO2 was observed in coarse roots to a depth of 20 cm, and fine root area index to a depth of 30 cm. Total fine root biomass was positively affected by elevated CO2 at the end of the experiment, but not by species diversity. Our data suggest that existing biogeochemical cycling models parameterized with data from species grown in monoculture may be underestimating the belowground response to global change. © 2012 Blackwell Publishing Ltd.

Comparative effects of simulated acid rain of different ratios of SO42- to NO3- on fine root in subtropical plantation of China.

PubMed

Liu, Xin; Zhao, Wenrui; Meng, Miaojing; Fu, Zhiyuan; Xu, Linhao; Zha, Yan; Yue, Jianmin; Zhang, Shuifeng; Zhang, Jinchi

2018-03-15

The influence of acid rain on forest trees includes direct effects on foliage as well as indirect soil-mediated effects that cause a reduction in fine-root growth. In addition, the concentration of NO 3 - in acid rain increases with the rapidly growing of nitrogen deposition. In this study, we investigated the impact of simulated acid rain with different SO 4 2- /NO 3 - (S/N) ratios, which were 5:1 (S), 1:1 (SN) and 1:5 (N), on fine-root growth from March 2015 to February 2016. Results showed that fine roots were more sensitive to the effects of acid rain than soils in the short-term. Both soil pH and fine root biomass (FRB) significantly decreased as acid rain pH decreased, and also decreased with the percentage of NO 3 - increased in acid rain. Acid rain pH significantly influenced soil total carbon and available potassium in summer. Higher acidity level (pH=2.5), especially of the N treatments, had the strongest inhibitory impact on soil microbial activity after summer. The structural equation modelling results showed that acid rain S/N ratio and pH had stronger direct effects on FRB than indirect effects via changed soil and fine root properties. Fine-root element contents and antioxidant enzymes activities were significantly affected by acid rain S/N ratio and pH during most seasons. Fine-root Al ion content, Ca/Al, Mg/Al ratios and catalase activity were used as better indicators than soil parameters for evaluating the effects of different acid rain S/N ratios and pH on forests. Our results suggest that the ratio of SO 4 2- to NO 3 - in acid rain is an important factor which could affect fine-root growth in subtropical forests of China. Copyright © 2017. Published by Elsevier B.V.

Root biomass, turnover and net primary productivity of a coffee agroforestry system in Costa Rica: effects of soil depth, shade trees, distance to row and coffee age

PubMed Central

Defrenet, Elsa; Roupsard, Olivier; Van den Meersche, Karel; Charbonnier, Fabien; Pastor Pérez-Molina, Junior; Khac, Emmanuelle; Prieto, Iván; Stokes, Alexia; Roumet, Catherine; Rapidel, Bruno; de Melo Virginio Filho, Elias; Vargas, Victor J.; Robelo, Diego; Barquero, Alejandra; Jourdan, Christophe

2016-01-01

Background and Aims In Costa Rica, coffee (Coffea arabica) plants are often grown in agroforests. However, it is not known if shade-inducing trees reduce coffee plant biomass through root competition, and hence alter overall net primary productivity (NPP). We estimated biomass and NPP at the stand level, taking into account deep roots and the position of plants with regard to trees. Methods Stem growth and root biomass, turnover and decomposition were measured in mixed coffee/tree (Erythrina poeppigiana) plantations. Growth ring width and number at the stem base were estimated along with stem basal area on a range of plant sizes. Root biomass and fine root density were measured in trenches to a depth of 4 m. To take into account the below-ground heterogeneity of the agroforestry system, fine root turnover was measured by sequential soil coring (to a depth of 30 cm) over 1 year and at different locations (in full sun or under trees and in rows/inter-rows). Allometric relationships were used to calculate NPP of perennial components, which was then scaled up to the stand level. Key Results Annual ring width at the stem base increased up to 2·5 mm yr−1 with plant age (over a 44-year period). Nearly all (92 %) coffee root biomass was located in the top 1·5 m, and only 8 % from 1·5 m to a depth of 4 m. Perennial woody root biomass was 16 t ha−1 and NPP of perennial roots was 1·3 t ha−1 yr−1. Fine root biomass (0–30 cm) was two-fold higher in the row compared with between rows. Fine root biomass was 2·29 t ha−1 (12 % of total root biomass) and NPP of fine roots was 2·96 t ha−1 yr−1 (69 % of total root NPP). Fine root turnover was 1·3 yr−1 and lifespan was 0·8 years. Conclusions Coffee root systems comprised 49 % of the total plant biomass; such a high ratio is possibly a consequence of shoot pruning. There was no significant effect of trees on coffee fine root biomass, suggesting that coffee root systems are very competitive in the topsoil. PMID:27551026

Winter climate change and fine root biogenic silica in sugar maple trees (Acer saccharum): Implications for silica in the Anthropocene

NASA Astrophysics Data System (ADS)

Maguire, Timothy J.; Templer, Pamela H.; Battles, John J.; Fulweiler, Robinson W.

2017-03-01

Winter temperatures are projected to increase over the next century, leading to reductions in winter snowpack and increased frequency of soil freezing in many northern forest ecosystems. Here we examine biogenic silica (BSi) concentrations in sugar maple (Acer saccharum) fine roots collected from a snow manipulation experiment at Hubbard Brook Experimental Forest (New Hampshire, USA). Increased soil freezing significantly lowered the BSi content of sugar maple fine roots potentially decreasing their capacity to take up water and dissolved nutrients. The reduced silica uptake (8 ± 1 kmol silica km-2) by sugar maple fine roots is comparable to silica export from temperate forest watersheds. We estimate that fine roots account for 29% of sugar maple BSi, despite accounting for only 4% of their biomass. These results suggest that increased frequency of soil freezing will reduce silica uptake by temperate tree roots, thereby changing silica availability in downstream receiving waters.

Fine root dynamics across a chronosequence of upland temperate deciduous forests

Treesearch

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

2000-01-01

Following a major disturbance event in forests that removes most of the standing vegetation, patterns of fine root growth, mortality, and decomposition may be altered from the pre-disturbance conditions. The objective of this study was to describe the changes in the seasonal and spatial dynamics of fine root growth, mortality, and decomposition that occur following...

ASSESSING THE EFFECTS OF ELEVATED ATMOSP;HERIC CO2 AND TEMPERATURE ON FINE ROOT PRODUCTION AND MORTALITY IN FORESTED SYSTEMS

EPA Science Inventory

Little is known about the effects of global climate change on the production and mortality of fine roots. To better understand these processes we have conducted a number of studies to investigate the factors that influence the production and mortality of fine roots in coniferous...

EFFECTS OF CO2 AND TEMPERATURE ON FINE ROOT PRODUCTION AND MORTALITY IN DOUGLAS FIR

EPA Science Inventory

Little is known about the effects of global climate change on the production and mortality of fine roots. We conducted a 4-year study to determine the effects of elevated CO2 and temperature on Douglas fir fine ( 2 mm in diameter) roots. The study was conducted in sun-lit cont...

Belowground Nutrient Dynamics Following Three Harvest Intensities on the Pearl River Floodplain, Mississippi

Treesearch

E.B. Schilling; B.G. Lockaby; Robert Rummer

1999-01-01

Abstract: The influence of clear and partial cut harvests on belowground nutrient cycling processes was examined on the Pearl River floodplain, Mississippi. Foci examined by this study included fine root biomass and detritus, fine root production, fine root nutrient contents, soil respiration rates, and microbial biomass C, N, and P during the first...

Below-ground effects of enhanced tropospheric ozone and drought in a beech/spruce forest (Fagus sylvatica L. / Picea abies [L.] Karst)

EPA Science Inventory

The effects of experimentally elevated O3 on soil respiration rates, standing fine-root biomass, fine-root production and δ13C signature of newly produced fine roots were investigated in an adult European beech/Norway spruce forest in Germany during two subsequent years with cont...

Fine-root growth in a forested bog is seasonally dynamic, but shallowly distributed in nutrient-poor peat

Treesearch

Colleen M. Iversen; Joanne Childs; Richard J. Norby; Todd A. Ontl; Randall K. Kolka; Deanne J. Brice; Karis J. McFarlane; Paul J. Hanson

2017-01-01

Background and aims. Fine roots contribute to ecosystem carbon, water, and nutrient fluxes through resource acquisition, respiration, exudation, and turnover, but are understudied in peatlands. We aimed to determine how the amount and timing of fine-root growth in a forested, ombrotrophic bog varied across gradients of vegetation density, peat...

Organic matter and nutrients associated with fine root turnover in a white oak stand. [Quercus albus

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

Joslin, J.D.; Henderson, G.S.

1987-06-01

Organic matter and nutrients cycled by fine root turnover were quantified in a mature white oak (Quercus alba L.) stand and compared to contributions from litterfall. The budget method, a revised version of the traditional repeated sampling method, was used to measure root turnover. The magnitude of the live and dead pools of three size classes of fine (<5 mm diameter) roots were monitored bimonthly for 14 months. Decomposition rates over these intervals were also measured, while production and mortality were calculated. Litterfall was collected simultaneously, and the nutrient concentrations of the various detritus components determined. Root pools fluctuated less,more » and total root turnover biomass (220 g m/sup -2/ yr/sup -1/) was also less than previously noted in most other stands studied. Fine root turnover accounted for 30% of the total detritus production and 20-40% of the turnover of the five macronutrients (N, P, K, Ca, Mg) studied. Differences with previous studies suggest that there may be rather large species and/or site-related differences in the amount of energy various stands allocate for fine root maintenance. For. Sci. 33(2):330-346.« less

Moving forward with fine-root definitions and research

DOE PAGES

McCormack, M. Luke; Iversen, Colleen M.; Eissenstat, David M.

2016-08-30

Here, in the letter published in this issue of New Phytologist (pp. 310-312), 'Fine roots - functional definition expanded to crop species?' Dr. Zobel emphasizes the importance of heterogeneity within crop-root systems.

DNA analysis of soil extracts can be used to investigate fine root depth distribution of trees

PubMed Central

Bithell, Sean L.; Tran-Nguyen, Lucy T. T.; Hearnden, Mark N.; Hartley, Diana M.

2015-01-01

Understanding the root distribution of trees by soil coring is time-consuming as it requires the separation of roots from soil and classification of roots into particular size classes. This labour-intensive process can limit sample throughput and therefore sampling intensity. We investigated the use of quantitative polymerase chain reaction (qPCR) on soil DNA extractions to determine live fine root DNA density (RDD, mg DNA m−2) for mango (Mangifera indica) trees. The specificity of the qPCR was tested against DNA extracted from 10 mango cultivars and 14 weed species. All mango cultivars and no weeds were detected. Mango DNA was successfully quantified from control soil spiked with mango roots and weed species. The DNA yield of mango root sections stored in moist soil at 23–28 °C declined after 15 days to low concentrations as roots decayed, indicating that dead root materials in moist soil would not cause false-positive results. To separate large roots from samples, a root separation method for field samples was used to target the root fragments remaining in sieved (minimum 2 mm aperture) soil for RDD comparisons. Using this method we compared the seasonal RDD values of fine roots for five mango rootstock cultivars in a field trial. The mean cultivar DNA yields by depth from root fragments in the sieved soil samples had the strongest relationship (adjusted multiple R2 = 0.9307, P < 0.001) with the dry matter (g m−2) of fine (diameter <0.64 mm) roots removed from the soil by sieving. This method provides a species-specific and rapid means of comparing the distribution and concentration of live fine roots of trees in orchards using soil samples up to 500 g. PMID:25552675

Linking fine root morphology, hydraulic functioning, and shade tolerance of trees

USDA-ARS?s Scientific Manuscript database

Understanding root traits and trade-offs in their functioning is important for understanding plant functioning in natural ecosystems as well as agricultural systems. The aim of the present study was to determine the relationship between root morphology and the hydraulic characteristics of fine roots...

Root length, biomass, tissue chemistry and mycorrhizal colonization following 14 years of CO2 enrichment and 6 years of N fertilization in a warm temperate forest.

PubMed

Taylor, Benton N; Strand, Allan E; Cooper, Emily R; Beidler, Katilyn V; Schönholz, Marcos; Pritchard, Seth G

2014-09-01

Root systems serve important roles in carbon (C) storage and resource acquisition required for the increased photosynthesis expected in CO2-enriched atmospheres. For these reasons, understanding the changes in size, distribution and tissue chemistry of roots is central to predicting the ability of forests to capture anthropogenic CO2. We sampled 8000 cm(3) soil monoliths in a pine forest exposed to 14 years of free-air-CO2-enrichment and 6 years of nitrogen (N) fertilization to determine changes in root length, biomass, tissue C : N and mycorrhizal colonization. CO2 fumigation led to greater root length (98%) in unfertilized plots, but root biomass increases under elevated CO2 were only found for roots <1 mm in diameter in unfertilized plots (59%). Neither fine root [C] nor [N] was significantly affected by increased CO2. There was significantly less root biomass in N-fertilized plots (19%), but fine root [N] and [C] both increased under N fertilization (29 and 2%, respectively). Mycorrhizal root tip biomass responded positively to CO2 fumigation in unfertilized plots, but was unaffected by CO2 under N fertilization. Changes in fine root [N] and [C] call for further study of the effects of N fertilization on fine root function. Here, we show that the stimulation of pine roots by elevated CO2 persisted after 14 years of fumigation, and that trees did not rely exclusively on increased mycorrhizal associations to acquire greater amounts of required N in CO2-enriched plots. Stimulation of root systems by CO2 enrichment was seen primarily for fine root length rather than biomass. This observation indicates that studies measuring only biomass might overlook shifts in root systems that better reflect treatment effects on the potential for soil resource uptake. These results suggest an increase in fine root exploration as a primary means for acquiring additional soil resources under elevated CO2. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Changes in fine root dynamics and distribution along a chronosequence of upland oak-hickory forests

Treesearch

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

1997-01-01

Central Hardwood forests regenerate rapidly following a major disturbance like a clear-cut. The subsequent aboveground growth and development of the resulting stands have been well-documented for these forests. However, the belowground components, specifically the dynamics of fine roots, are not well understood. Fine roots are the main vectors through which plants...

Production dynamics of fine roots in beech forests: possible mechanism of resource allocation between above- and below-ground production

NASA Astrophysics Data System (ADS)

Nakahata, R.; Osawa, A.; Naramoto, M.; Mizunaga, H.; Sato, M.

2017-12-01

The masting phenomenon that seed production has large annual variation with spatial synchrony appears generally in beeches. Therefore, net primary production and carbon allocation mechanism in beech forests may differ among several years in relation to annual variation of seed production. On the other hand, fine roots play key roles in carbon dynamics and nutrient and water acquisition of an ecosystem. Evaluation of fine root dynamics is essential to understand long-term dynamics of production in forest ecosystems. Moreover, the influence of mast seeding on resource allocation should be clarified in such beech forests. The aim of this study is to clarify possible relationships between the patterns of above- and below-ground production in relation to the masting events using observation data of litter fall and fine root dynamics. We applied the litter trap method and a minirhizotron method in a cool-temperate natural forest dominated by beech (Fagus crenata Blume). Ten litter traps were set from 2008 to 2016, then annual leaf and seed production were estimated. Four minirhizotron tubes were buried in Aug. 2008 and soil profiles were scanned monthly until Nov. 2016 during the periods of no snow covering. The scanned soil profiles were analyzed for calculating fine root production using the WinRHIZO Tron software. In the present study site, rich production of mast seeding occurred biennially and fine root production showed various seasonal patterns. There was no significant correlation between seed production and annual fine root production in the same year. However, seed production had a positive correlation with fine root production in autumn in the previous year and indicated a negative correlation with that in autumn in the current year. These results indicate that higher fine root production has led to increased nutrient acquisition, which resulted in rich seed production in the next year. It is also suppressed after the masting events due to shortage in resources. This interpretation of the mechanism may be reasonable because the number of flowers and seeds in the current year may have been determined in summer of the previous year. The patterns of fine root production are reasonably changed to occur the masting phenomenon of beeches.

Trampling, defoliation and physiological integration affect growth, morphological and mechanical properties of a root-suckering clonal tree.

PubMed

Xu, Liang; Yu, Fei-Hai; van Drunen, Elles; Schieving, Feike; Dong, Ming; Anten, Niels P R

2012-04-01

Grazing is a complex process involving the simultaneous occurrence of both trampling and defoliation. Clonal plants are a common feature of heavily grazed ecosystems where large herbivores inflict the simultaneous pressures of trampling and defoliation on the vegetation. We test the hypothesis that physiological integration (resource sharing between interconnected ramets) may help plants to deal with the interactive effects of trampling and defoliation. In a field study, small and large ramets of the root-suckering clonal tree Populus simonii were subjected to two levels of trampling and defoliation, while connected or disconnected to other ramets. Plant responses were quantified via survival, growth, morphological and stem mechanical traits. Disconnection and trampling increased mortality, especially in small ramets. Trampling increased stem length, basal diameter, fibrous root mass, stem stiffness and resistance to deflection in connected ramets, but decreased them in disconnected ones. Trampling decreased vertical height more in disconnected than in connected ramets, and reduced stem mass in disconnected ramets but not in connected ramets. Defoliation reduced basal diameter, leaf mass, stem mass and leaf area ratio, but did not interact with trampling or disconnection. Although clonal integration did not influence defoliation response, it did alleviate the effects of trampling. We suggest that by facilitating resource transport between ramets, clonal integration compensates for trampling-induced damage to fine roots.

Linking root traits to nutrient foraging in arbuscular mycorrhizal trees in a temperate forest.

PubMed

Eissenstat, David M; Kucharski, Joshua M; Zadworny, Marcin; Adams, Thomas S; Koide, Roger T

2015-10-01

The identification of plant functional traits that can be linked to ecosystem processes is of wide interest, especially for predicting vegetational responses to climate change. Root diameter of the finest absorptive roots may be one plant trait that has wide significance. Do species with relatively thick absorptive roots forage in nutrient-rich patches differently from species with relatively fine absorptive roots? We measured traits related to nutrient foraging (root morphology and architecture, root proliferation, and mycorrhizal colonization) across six coexisting arbuscular mycorrhizal (AM) temperate tree species with and without nutrient addition. Root traits such as root diameter and specific root length were highly correlated with root branching intensity, with thin-root species having higher branching intensity than thick-root species. In both fertilized and unfertilized soil, species with thin absorptive roots and high branching intensity showed much greater root length and mass proliferation but lower mycorrhizal colonization than species with thick absorptive roots. Across all species, fertilization led to increased root proliferation and reduced mycorrhizal colonization. These results suggest that thin-root species forage more by root proliferation, whereas thick-root species forage more by mycorrhizal fungi. In mineral nutrient-rich patches, AM trees seem to forage more by proliferating roots than by mycorrhizal fungi. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

The relationship between root hydraulics and scion vigour across Vitis rootstocks: what role do root aquaporins play?

PubMed Central

McElrone, A. J.

2012-01-01

Vitis vinifera scions are commonly grafted onto rootstocks of other grape species to influence scion vigour and provide resistance to soil-borne pests and abiotic stress; however, the mechanisms by which rootstocks affect scion physiology remain unknown. This study characterized the hydraulic physiology of Vitis rootstocks that vary in vigour classification by investigating aquaporin (VvPIP) gene expression, fine-root hydraulic conductivity (Lp r), % aquaporin contribution to Lp r, scion transpiration, and the size of root systems. Expression of several VvPIP genes was consistently greater in higher-vigour rootstocks under favourable growing conditions in a variety of media and in root tips compared to mature fine roots. Similar to VvPIP expression patterns, fine-root Lp r and % aquaporin contribution to Lp r determined under both osmotic (Lp r Osm) and hydrostatic (Lp r Hyd) pressure gradients were consistently greater in high-vigour rootstocks. Interestingly, the % aquaporin contribution was nearly identical for Lp r Osm and Lp r Hyd even though a hydrostatic gradient would induce a predominant flow across the apoplastic pathway. In common scion greenhouse experiments, leaf area-specific transpiration (E) and total leaf area increased with rootstock vigour and were positively correlated with fine-root Lp r. These results suggest that increased canopy water demands for scion grafted onto high-vigour rootstocks are matched by adjustments in root-system hydraulic conductivity through the combination of fine-root Lp r and increased root surface area. PMID:23136166

Root biomass, turnover and net primary productivity of a coffee agroforestry system in Costa Rica: effects of soil depth, shade trees, distance to row and coffee age.

PubMed

Defrenet, Elsa; Roupsard, Olivier; Van den Meersche, Karel; Charbonnier, Fabien; Pastor Pérez-Molina, Junior; Khac, Emmanuelle; Prieto, Iván; Stokes, Alexia; Roumet, Catherine; Rapidel, Bruno; de Melo Virginio Filho, Elias; Vargas, Victor J; Robelo, Diego; Barquero, Alejandra; Jourdan, Christophe

2016-08-21

In Costa Rica, coffee (Coffea arabica) plants are often grown in agroforests. However, it is not known if shade-inducing trees reduce coffee plant biomass through root competition, and hence alter overall net primary productivity (NPP). We estimated biomass and NPP at the stand level, taking into account deep roots and the position of plants with regard to trees. Stem growth and root biomass, turnover and decomposition were measured in mixed coffee/tree (Erythrina poeppigiana) plantations. Growth ring width and number at the stem base were estimated along with stem basal area on a range of plant sizes. Root biomass and fine root density were measured in trenches to a depth of 4 m. To take into account the below-ground heterogeneity of the agroforestry system, fine root turnover was measured by sequential soil coring (to a depth of 30 cm) over 1 year and at different locations (in full sun or under trees and in rows/inter-rows). Allometric relationships were used to calculate NPP of perennial components, which was then scaled up to the stand level. Annual ring width at the stem base increased up to 2·5 mm yr -1 with plant age (over a 44-year period). Nearly all (92 %) coffee root biomass was located in the top 1·5 m, and only 8 % from 1·5 m to a depth of 4 m. Perennial woody root biomass was 16 t ha -1 and NPP of perennial roots was 1·3 t ha -1 yr -1 Fine root biomass (0-30 cm) was two-fold higher in the row compared with between rows. Fine root biomass was 2·29 t ha -1 (12 % of total root biomass) and NPP of fine roots was 2·96 t ha -1 yr -1 (69 % of total root NPP). Fine root turnover was 1·3 yr -1 and lifespan was 0·8 years. Coffee root systems comprised 49 % of the total plant biomass; such a high ratio is possibly a consequence of shoot pruning. There was no significant effect of trees on coffee fine root biomass, suggesting that coffee root systems are very competitive in the topsoil. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Plastic responses of native plant root systems to the presence of an invasive annual grass.

PubMed

Phillips, Allison J; Leger, Elizabeth A

2015-01-01

• The ability to respond to environmental change via phenotypic plasticity may be important for plants experiencing disturbances such as climate change and plant invasion. Responding to belowground competition through root plasticity may allow native plants to persist in highly invaded systems such as the cold deserts of the Intermountain West, USA.• We investigated whether Poa secunda, a native bunchgrass, could alter root morphology in response to nutrient availability and the presence of a competitive annual grass. Seeds from 20 families were grown with high and low nutrients and harvested after 50 d, and seeds from 48 families, grown with and without Bromus tectorum, were harvested after ∼2 or 6 mo. We measured total biomass, root mass fraction, specific root length (SRL), root tips, allocation to roots of varying diameter, and plasticity in allocation.• Plants had many parallel responses to low nutrients and competition, including increased root tip production, a trait associated with tolerance to reduced resources, though families differed in almost every trait and correlations among trait changes varied among experiments, indicating flexibility in plant responses. Seedlings actively increased SRL and fine root allocation under competition, while older seedlings also increased coarse root allocation, a trait associated with increased tolerance, and increased root mass fraction.• The high degree of genetic variation for root plasticity within natural populations could aid in the long-term persistence of P. secunda because phenotypic plasticity may allow native species to persist in invaded and fluctuating resource environments. © 2015 Botanical Society of America, Inc.

Long-Term Effects of Season of Prescribed Burn on the Fine-Root Growth, Root Carbohydrates, and Foliar Dynamics of Mature Longleaf Pine

Treesearch

Eric A. Kuehler; Mary Anne Sword Sayer; James D. Haywood; C. Dan Andries

2004-01-01

Depending on the season and intensity of fire, as well as the phenology of foliage and new root growth, fire may damage foliage, and subsequently decrease whole-crown carbon fixation and allocation to the root system. In central Louisiana the authors investigated how season of prescribed burning affects fine-root dynamics, root carbohydrate relations, and leaf area...

Distribution of fine roots of ponderosa pine and Douglas-fir in a central Idaho forest

Treesearch

Gabriel Dumm; Lauren Fins; Russell T. Graham; Theresa B. Jain

2008-01-01

This study describes soil horizon depth and fine root distribution in cores collected at two distances from the boles of Douglas-fir and ponderosa pine trees at a study site in a central Idaho forest. Concentration and content of fine roots extracted from soil cores were compared among species, soil horizons, tree size, and distance from bole. Approximately 80% of...

CO2 and N-fertilization effects on fine-root length, production, and mortality: a 4-year ponderosa pine study.

PubMed

Phillips, Donald L; Johnson, Mark G; Tingey, David T; Storm, Marjorie J; Ball, J Timothy; Johnson, Dale W

2006-06-01

We conducted a 4-year study of juvenile Pinus ponderosa fine root (< or =2 mm) responses to atmospheric CO2 and N-fertilization. Seedlings were grown in open-top chambers at three CO2 levels (ambient, ambient+175 mumol/mol, ambient+350 mumol/mol) and three N-fertilization levels (0, 10, 20 g m(-2) year(-1)). Length and width of individual roots were measured from minirhizotron video images bimonthly over 4 years starting when the seedlings were 1.5 years old. Neither CO2 nor N-fertilization treatments affected the seasonal patterns of root production or mortality. Yearly values of fine-root length standing crop (m m(-2)), production (m m(-2) year(-1)), and mortality (m m(-2) year(-1)) were consistently higher in elevated CO2 treatments throughout the study, except for mortality in the first year; however, the only statistically significant CO2 effects were in the fine-root length standing crop (m m(-2)) in the second and third years, and production and mortality (m m(-2) year(-1)) in the third year. Higher mortality (m m(-2) year(-1)) in elevated CO2 was due to greater standing crop rather than shorter life span, as fine roots lived longer in elevated CO2. No significant N effects were noted for annual cumulative production, cumulative mortality, or mean standing crop. N availability did not significantly affect responses of fine-root standing crop, production, or mortality to elevated CO2. Multi-year studies at all life stages of trees are important to characterize belowground responses to factors such as atmospheric CO2 and N-fertilization. This study showed the potential for juvenile ponderosa pine to increase fine-root C pools and C fluxes through root mortality in response to elevated CO2.

Differential responses of grapevine rootstocks to water stress are associated with adjustments in fine root hydraulic physiology and suberization

USDA-ARS?s Scientific Manuscript database

Water deficits are known to alter fine root structure and function, but little is known about how these responses contribute to differences in drought resistance across grapevine rootstocks. We studied how water deficit affects root anatomical and physiological characteristics in two grapevine root...

A worldview of root traits: the influence of ancestry, growth form, climate and mycorrhizal association on the functional trait variation of fine-root tissues in seed plants.

PubMed

Valverde-Barrantes, Oscar J; Freschet, Grégoire T; Roumet, Catherine; Blackwood, Christopher B

2017-09-01

Fine-root traits play key roles in ecosystem processes, but the drivers of fine-root trait diversity remain poorly understood. The plant economic spectrum (PES) hypothesis predicts that leaf and root traits evolved in coordination. Mycorrhizal association type, plant growth form and climate may also affect root traits. However, the extent to which these controls are confounded with phylogenetic structuring remains unclear. Here we compiled information about root and leaf traits for > 600 species. Using phylogenetic relatedness, climatic ranges, growth form and mycorrhizal associations, we quantified the importance of these factors in the global distribution of fine-root traits. Phylogenetic structuring accounts for most of the variation for all traits excepting root tissue density, with root diameter and nitrogen concentration showing the strongest phylogenetic signal and specific root length showing intermediate values. Climate was the second most important factor, whereas mycorrhizal type had little effect. Substantial trait coordination occurred between leaves and roots, but the strength varied between growth forms and clades. Our analyses provide evidence that the integration of roots and leaves in the PES requires better accounting of the variation in traits across phylogenetic clades. Inclusion of phylogenetic information provides a powerful framework for predictions of belowground functional traits at global scales. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Fine-root biomass and fluxes of soil carbon in young stands of paper birch and trembling aspen as affected by elevated atmospheric CO2 and tropospheric O3

Treesearch

J. S. King; K. S. Pregitzer; D. R. Zak; J. Sober; J. G. Isebrands; R. E. Dickson; G. R. Hendrey; D. F. Karnosky

2001-01-01

Rising atmospheric CO2 may stimulate future forest productivity, possibly increasing carbon storage in terrestrial ecosystems, but how tropospheric ozone will modify this response is unknown. Because of the importance of fine roots to the belowground C cycle, we monitored fine-root biomass and associated C fluxes in regenerating stands of...

Mean Annual Temperature Drives Microbial Nitrogen Cycling and Fine Root Nutrient Foraging Across a Tropical Montane Wet Forest Elevation Gradient

NASA Astrophysics Data System (ADS)

Pierre, S.; Litton, C. L. M.; Giardina, C. P.; Sparks, J. P.; Groffman, P. M.; Hewson, I.; Fahey, T. J.

2017-12-01

Mean annual temperature (MAT) is positively correlated with rates of primary production and carbon (C) turnover in forests globally, but the underlying biotic drivers of these relationships remain poorly resolved. We hypothesized that (1) MAT increases nitrifier abundance and thereby nitrate (NO-) bioavailability in soils and (2) increased NO- bioavailability reduces fine root nitrogen (N) demand. We used an ecologically well-constrained natural elevation gradient (13˚C -18˚C) in a tropical wet motane forest on the Island of Hawaii to study to role of MAT in situ. Our previous work showed that MAT drives increased soil NO- bioavailability in situ (r²=0.79, P=0.003), and indicated that the abundance of ammonia oxidizing archaea is strongly and positively correlated with MAT in situ (r²=0.34, P<0.001; Pierre et. al. 2017). Using fertilized fine root ingrowth cores (+N, +P, +N+P, control) across the same MAT gradient, we found that increasing MAT and bulk soil NO- bioavailability produced a significant negative fine root response to the +N+P treatment (P=0.023), and no response to other fertilization treatments. Increasing MAT and soil NO- bioavailability led to increased percent arbuscular mycorrhizal (AM) colonization of fine roots (r²=0.43, P=0.004), but no treatment effect on AM colonization was observed. Our results suggest that N and P generally co-limit fine root foraging across the gradient, while higher MAT and bulk soil NO- bioavailability interact to reduce fine root foraging effort. Further, higher MAT and greater N fertility in soils may reduce the C limitation of AM fungal colonization. We conclude that MAT drives N-rich conditions, which allow for lower N foraging effort, but greater C investment in P acquisition through AM fine root colonization.

Challenges to estimating whole forest root biomass with ground penetrating radar

NASA Astrophysics Data System (ADS)

Butnor, J. R.

2016-12-01

Over the past two decades, substantial technical advances have been made in detecting tree roots with ground penetrating radar (GPR). Under favorable soil dielectric conditions, root location, depth, diameter and mass estimates are possible in the field. With careful notation of survey lines, three dimensional reconstructions of root architecture may also be achieved. The technique has been very useful for quantifying lateral root biomass in silvicultural studies, but is not yet a standalone technique for estimating root biomass in forests. The purpose of this presentation is to highlight the limitations of GPR in the field to stimulate discussion on how to overcome these challenges. Under field conditions, surface-based antennas with frequencies of 400 to 1500 MHz cannot detect fine roots (<2 mm diameter), vertical taproots, below-stump mass, decayed roots or separate roots by species. Higher frequency antennas designed for concrete inspection are available, but penetration through forest soils would be marginal. Over half of the root mass in many Pinus species is in the taproot which is undetectable in part or whole by GPR. This presents challenges to stand-level quantification as whole classes of biomass and structures are not reliably detected. Lack of automation of data processing and interpretation steps currently makes data analysis arduous and in some cases subject to interpretation by an expert user. Forests have a high degree of heterogeneity in surface conditions (e.g., holes, soil moisture, stems, woody and herbaceous plants) that may prevent antennas from coupling with the surface to propagate EM waves and receive reflections. What is the potential for open source data analysis programs to be developed and shared? How will new digital, multi-frequency antennas improve resolution? Can air launched antennas be developed that have both the depth penetration and resolution to detect roots? Are purpose-designed bore hole antenna needed for imaging taproots?

Overestimation of Crop Root Biomass in Field Experiments Due to Extraneous Organic Matter

PubMed Central

Hirte, Juliane; Leifeld, Jens; Abiven, Samuel; Oberholzer, Hans-Rudolf; Hammelehle, Andreas; Mayer, Jochen

2017-01-01

Root biomass is one of the most relevant root parameters for studies of plant response to environmental change, soil carbon modeling or estimations of soil carbon sequestration. A major source of error in root biomass quantification of agricultural crops in the field is the presence of extraneous organic matter in soil: dead roots from previous crops, weed roots, incorporated above ground plant residues and organic soil amendments, or remnants of soil fauna. Using the isotopic difference between recent maize root biomass and predominantly C3-derived extraneous organic matter, we determined the proportions of maize root biomass carbon of total carbon in root samples from the Swiss long-term field trial “DOK.” We additionally evaluated the effects of agricultural management (bio-organic and conventional), sampling depth (0–0.25, 0.25–0.5, 0.5–0.75 m) and position (within and between maize rows), and root size class (coarse and fine roots) as defined by sieve mesh size (2 and 0.5 mm) on those proportions, and quantified the success rate of manual exclusion of extraneous organic matter from root samples. Only 60% of the root mass that we retrieved from field soil cores was actual maize root biomass from the current season. While the proportions of maize root biomass carbon were not affected by agricultural management, they increased consistently with soil depth, were higher within than between maize rows, and were higher in coarse (>2 mm) than in fine (≤2 and >0.5) root samples. The success rate of manual exclusion of extraneous organic matter from root samples was related to agricultural management and, at best, about 60%. We assume that the composition of extraneous organic matter is strongly influenced by agricultural management and soil depth and governs the effect size of the investigated factors. Extraneous organic matter may result in severe overestimation of recovered root biomass and has, therefore, large implications for soil carbon modeling and estimations of the climate change mitigation potential of soils. PMID:28298919

Contrasting fine-root production, survival and soil CO2 efflux in pine and poplar plantation

Treesearch

M. D. Coleman; Richard E. Dickson; J. G. Isebrands

2000-01-01

Tree root activity, including fine-root production, turnover and metabolic activity are significant components of forest productivity and nutrient cycling. Differences in root activity among forest types are not well known. A 3-year study was undertaken in red pine (Pinus resinosa Ait.) and hybrid poplar (Populus tristis X P.

Contrasting fine-root production, survival and soil CO2 efflux in pine and poplar plantations

Treesearch

M.D. Coleman; R.E. Dickson; J.G. Isebrands

2000-01-01

Tree root activity, including fine-root production, turnover and metabolic activity are significant components of forest productivity and nutrient cycling. Differences in root activity among forest types are not well known. A 3-year study was undertaken in red pine (Pinus resinosa Ait.) and hybrid poplar (Populus tristis X P.

Long-term dynamics of pine and hardwood litter in contrasting environments: Toward a global model of decomposition

Treesearch

Henry L. Gholz; David A. Wedin; Stephen M. Smitherman; Mark E. Harmon; William J. Parton

2000-01-01

We analysed data on mass loss after five years of decomposition in the field from both fine root and leaf litters from two highly contrasting trees, Drypetes glallca, a tropical hardwood tree from Puerto Rico, and pine species from North America as part of the Long-Term Intersite Decomposition Experiment (LIDET). LIDET is a reciprocal litterbag study...

Fine root dynamics and forest production across a calcium gradient in northern hardwood and conifer ecosystems

USGS Publications Warehouse

Park, B.B.; Yanai, R.D.; Fahey, T.J.; Bailey, S.W.; Siccama, T.G.; Shanley, J.B.; Cleavitt, N.L.

2008-01-01

Losses of soil base cations due to acid rain have been implicated in declines of red spruce and sugar maple in the northeastern USA. We studied fine root and aboveground biomass and production in five northern hardwood and three conifer stands differing in soil Ca status at Sleepers River, VT; Hubbard Brook, NH; and Cone Pond, NH. Neither aboveground biomass and production nor belowground biomass were related to soil Ca or Ca:Al ratios across this gradient. Hardwood stands had 37% higher aboveground biomass (P = 0.03) and 44% higher leaf litter production (P < 0.01) than the conifer stands, on average. Fine root biomass (<2 mm in diameter) in the upper 35 cm of the soil, including the forest floor, was very similar in hardwoods and conifers (5.92 and 5.93 Mg ha-1). The turnover coefficient (TC) of fine roots smaller than 1 mm ranged from 0.62 to 1.86 y-1 and increased significantly with soil exchangeable Ca (P = 0.03). As a result, calculated fine root production was clearly higher in sites with higher soil Ca (P = 0.02). Fine root production (biomass times turnover) ranged from 1.2 to 3.7 Mg ha-1 y-1 for hardwood stands and from 0.9 to 2.3 Mg ha-1 y -1 for conifer stands. The relationship we observed between soil Ca availability and root production suggests that cation depletion might lead to reduced carbon allocation to roots in these ecosystems. ?? 2008 Springer Science+Business Media, LLC.

Responses of nutrient capture and fine root morphology of subalpine coniferous tree Picea asperata to nutrient heterogeneity and competition

PubMed Central

Nan, Hongwei; Liang, Jin; Cheng, Xinying; Zhao, ChunZhang; Yin, HuaJun; Yin, ChunYing; Liu, Qing

2017-01-01

Investigating the responses of trees to the heterogeneous distribution of nutrients in soil and simultaneous presence of neighboring roots could strengthen the understanding of an influential mechanism on tree growth and provide a scientific basis for forest management. Here, we conducted two split-pot experiments to investigate the effects of nutrient heterogeneity and intraspecific competition on the fine root morphology and nutrient capture of Picea asperata. The results showed that P. asperata efficiently captured nutrients by increasing the specific root length (SRL) and specific root area (SRA) of first-and second-order roots and decreasing the tissue density of first-order roots to avoid competition for resources and space with neighboring roots. The nutrient heterogeneity and addition of fertilization did not affect the fine root morphology, but enhanced the P and K concentrations in the fine roots in the absence of a competitor. On the interaction between nutrient heterogeneity and competition, competition decreased the SRL and SRA but enhanced the capture of K under heterogeneous soil compared with under homogeneous soil. Additionally, the P concentration, but not the K concentration, was linearly correlated to root morphology in heterogeneous soil, even when competition was present. The results suggested that root morphological features were only stimulated when the soil nutrients were insufficient for plant growth and the nutrients accumulations by root were mainly affected by the soil nutrients more than the root morphology. PMID:29095947

Intra-annual changes in biomass, carbon, and nitrogen dynamics at 4-year old switchgrass field trials in West Tennessee, USA

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

Garten, Jr, C. T.; Smith, Jeffery L.; Tyler, Donald D.

2010-02-15

Switchgrass is a potential bioenergy crop that could promote soil C sequestration in some environments. We compared four cultivars on a well-drained Alfisol to test for differences in biomass, C, and N dynamics during the fourth growing season. There was no difference (P > 0.05) among cultivars and no significant cultivar x time interaction in analyses of dry mass, C stocks, or N stocks in aboveground biomass and surface litter. At the end of the growing season, mean (±SE) aboveground biomass was 2.1±0.13 kg m-2, and surface litter dry mass was approximately 50% of aboveground biomass. Prior to harvest, themore » live root:shoot biomass ratio was 0.76. There was no difference (P > 0.05) among cultivars for total biomass, C, and N stocks belowground. Total belowground biomass (90-cm soil depth) as well as coarse (greater than or equal to 1 mm diameter) and fine (< 1 mm diameter) live root biomass increased from April to October. Dead roots were less than 7% of live root biomass to a depth of 90 cm. Net production of total belowground biomass (505 ±132 g m-2) occurred in the last half of the growing season. The increase in total live belowground biomass (426 ±139 g m-2) was more or less evenly divided among rhizomes, coarse, and fine roots. The N budget for annual switchgrass production was closely balanced with 6.3 g N m-2 removed by harvest of aboveground biomass and 6.7 g N m-2 supplied by fertilization. At the location of our study in west Tennessee, intra-annual changes in biomass, C, and N stocks belowground were of greater importance to crop management for C sequestration than were differences among cultivars.« less

21 Tesla Fourier Transform Ion Cyclotron Resonance Mass Spectrometer Greatly Expands Mass Spectrometry Toolbox

NASA Astrophysics Data System (ADS)

Shaw, Jared B.; Lin, Tzu-Yung; Leach, Franklin E.; Tolmachev, Aleksey V.; Tolić, Nikola; Robinson, Errol W.; Koppenaal, David W.; Paša-Tolić, Ljiljana

2016-12-01

We provide the initial performance evaluation of a 21 Tesla Fourier transform ion cyclotron resonance mass spectrometer operating at the Environmental Molecular Sciences Laboratory at the Pacific Northwest National Laboratory. The spectrometer constructed for the 21T system employs a commercial dual linear ion trap mass spectrometer coupled to a FTICR spectrometer designed and built in-house. Performance gains from moving to higher magnetic field strength are exemplified by the measurement of peptide isotopic fine structure, complex natural organic matter mixtures, and large proteins. Accurate determination of isotopic fine structure was demonstrated for doubly charged Substance P with minimal spectral averaging, and 8158 molecular formulas assigned to Suwannee River Fulvic Acid standard with root-mean-square (RMS) error of 10 ppb. We also demonstrated superior performance for intact proteins; namely, broadband isotopic resolution of the entire charge state distribution of apo-transferrin (78 kDa) and facile isotopic resolution of monoclonal antibody under a variety of acquisition parameters (e.g., 6 s time-domains with absorption mode processing yielded resolution of approximately 1 M at m/z = 2700).

Roots Revealed - Neutron imaging insight of spatial distribution, morphology, growth and function

NASA Astrophysics Data System (ADS)

Warren, J.; Bilheux, H.; Kang, M.; Voisin, S.; Cheng, C.; Horita, J.; Perfect, E.

2013-05-01

Root production, distribution and turnover are not easily measured, yet their dynamics are an essential part of understanding and modeling ecosystem response to changing environmental conditions. Root age, order, morphology and mycorrhizal associations all regulate root uptake of water and nutrients, which along with along with root distribution determines plant response to, and impact on its local environment. Our objectives were to demonstrate the ability to non-invasively monitor fine root distribution, root growth and root functionality in Zea mays L. (maize) and Panicum virgatum L. (switchgrass) seedlings using neutron imaging. Plants were propagated in aluminum chambers containing sand then placed into a high flux cold neutron beam line. Dynamics of root distribution and growth were assessed by collecting consecutive CCD radiographs through time. Root functionality was assessed by tracking individual root uptake of water (H2O) or deuterium oxide (D2O) through time. Since neutrons strongly scatter H atoms, but not D atoms, biological materials such as plants are prime candidates for neutron imaging. 2D and 3D neutron radiography readily illuminated root structure, root growth, and relative plant and soil water content. Fungal hyphae associated with the roots were also visible and appeared as dark masses since their diameter was likely several orders of magnitude less than ~100 μm resolution of the detector. The 2D pulse-chase irrigation experiments with H2O and D2O successfully allowed observation of uptake and mass flow of water within the root system. Water flux within individual roots responded differentially to foliar illumination based on internal water potential gradients, illustrating the ability to track root functionality based on root size, order and distribution within the soil. (L) neutron image of switchgrass growing in sandy soil with 100 μm diameter roots (R) 3D reconstruction of maize seedling following neutron tomography

Fine root heterogeneity by branch order: exploring the discrepancy in root turnover estimates between minirhizotron and carbon isotopic methods

Treesearch

Dali Guo; Harbin Li; Robert J. Mitchell; Han Wenxuan; Joseph J. Hendricks; Timothy J. Fahey; Ronald L. Hendrick

2008-01-01

Fine roots constitute a large and dynamic component of the carbon cycles of terrestrial ecosystems. The reported fivefold discrepancy in turnover estimates between median longevity (ML) from minirhizotrons and mean residence time (MRT) using carbon isotopes may have global consequences.

Antioxidant tannins from stem bark and fine root of Casuarina equisetifolia.

PubMed

Zhang, Shang-Ju; Lin, Yi-Ming; Zhou, Hai-Chao; Wei, Shu-Dong; Lin, Guang-Hui; Ye, Gong-Fu

2010-08-16

Structures of condensed tannins from the stem bark and fine root of Casuarina equisetifolia were identified using MALDI-TOF MS and HPLC analyses. The condensed tannins from stem bark and fine root consist predominantly of procyanidin combined with prodelphinidin and propelargonidin, and epicatechin is the main extension unit. The condensed tannins had different polymer chain lengths, varying from trimers to tridecamer for stem bark and to pentadecamer for fine root. The antioxidant activities were measured by two models: 1,1-diphenyl-2- picrylhydrazyl (DPPH) radical scavenging activity and ferric reducing/ antioxidant power (FRAP). The condensed tannins extracted from C. equisetifolia showed very good DPPH radical scavenging activity and ferric reducing/ antioxidant power, suggesting that these extracts may be considered as new sources of natural antioxidants for food and nutraceutical products.

Parallel evolution of storage roots in morning glories (Convolvulaceae).

PubMed

Eserman, Lauren A; Jarret, Robert L; Leebens-Mack, James H

2018-05-29

Storage roots are an ecologically and agriculturally important plant trait that have evolved numerous times in angiosperms. Storage roots primarily function to store carbohydrates underground as reserves for perennial species. In morning glories, storage roots are well characterized in the crop species sweetpotato, where starch accumulates in storage roots. This starch-storage tissue proliferates, and roots thicken to accommodate the additional tissue. In morning glories, storage roots have evolved numerous times. The primary goal of this study is to understand whether this was through parallel evolution, where species use a common genetic mechanism to achieve storage root formation, or through convergent evolution, where storage roots in distantly related species are formed using a different set of genes. Pairs of species where one forms storage roots and the other does not were sampled from two tribes in the morning glory family, the Ipomoeeae and Merremieae. Root anatomy in storage roots and fine roots was examined. Furthermore, we sequenced total mRNA from storage roots and fine roots in these species and analyzed differential gene expression. Anatomical results reveal that storage roots of species in the Ipomoeeae tribe, such as sweetpotato, accumulate starch similar to species in the Merremieae tribe but differ in vascular tissue organization. In both storage root forming species, more genes were found to be upregulated in storage roots compared to fine roots. Further, we find that fifty-seven orthologous genes were differentially expressed between storage roots and fine roots in both storage root forming species. These genes are primarily involved in starch biosynthesis, regulation of starch biosynthesis, and transcription factor activity. Taken together, these results demonstrate that storage roots of species from both morning glory tribes are anatomically different but utilize a common core set of genes in storage root formation. This is consistent with a pattern of parallel evolution, thus highlighting the importance of examining anatomy together with gene expression to understand the evolutionary origins of ecologically and economically important plant traits.

Plant traits and decomposition: are the relationships for roots comparable to those for leaves?

PubMed Central

Birouste, Marine; Kazakou, Elena; Blanchard, Alain; Roumet, Catherine

2012-01-01

Background and Aims Fine root decomposition is an important determinant of nutrient and carbon cycling in grasslands; however, little is known about the factors controlling root decomposition among species. Our aim was to investigate whether interspecific variation in the potential decomposition rate of fine roots could be accounted for by root chemical and morphological traits, life history and taxonomic affiliation. We also investigated the co-ordinated variation in root and leaf traits and potential decomposition rates. Methods We analysed potential decomposition rates and the chemical and morphological traits of fine roots on 18 Mediterranean herbaceous species grown in controlled conditions. The results were compared with those obtained for leaves in a previous study conducted on similar species. Key Results Differences in the potential decomposition rates of fine roots between species were accounted for by root chemical composition, but not by morphological traits. The root potential decomposition rate varied with taxonomy, but not with life history. Poaceae, with high cellulose concentration and low concentrations of soluble compounds and phosphorus, decomposed more slowly than Asteraceae and Fabaceae. Patterns of root traits, including decomposition rate, mirrored those of leaf traits, resulting in a similar species clustering. Conclusions The highly co-ordinated variation of roots and leaves in terms of traits and potential decomposition rate suggests that changes in the functional composition of communities in response to anthropogenic changes will strongly affect biogeochemical cycles at the ecosystem level. PMID:22143881

Intraspecific variation in fine root respiration and morphology in response to in situ soil nitrogen fertility in a 100-year-old Chamaecyparis obtusa forest.

PubMed

Makita, Naoki; Hirano, Yasuhiro; Sugimoto, Takanobu; Tanikawa, Toko; Ishii, Hiroaki

2015-12-01

Soil N fertility has an effect on belowground C allocation, but the physiological and morphological responses of individual fine root segments to variations in N availability under field conditions are still unclear. In this study, the direction and magnitude of the physiological and morphological function of fine roots in response to variable in situ soil N fertility in a forest site were determined. We measured the specific root respiration (Rr) rate, N concentration and morphology of fine root segments with 1-3 branching orders in a 100-year-old coniferous forest of Chamaecyparis obtusa. Higher soil N fertility induced higher Rr rates, root N concentration, and specific root length (SRL), and lower root tissue density (RTD). In all fertility levels, the Rr rates were significantly correlated positively with root N and SRL and negatively with RTD. The regression slopes of respiration with root N and RTD were significantly higher along the soil N fertility gradient. Although no differences in the slopes of Rr and SRL relationship were found across the levels, there were significant shifts in the intercept along the common slope. These results suggest that a contrasting pattern in intraspecific relationships between specific Rr and N, RTD, and SRL exists among soils with different N fertility. Consequently, substantial increases in soil N fertility would exert positive effects on organ-scale root performance by covarying the Rr, root N, and morphology for their potential nutrient and water uptake.

Acclimation and soil moisture constrain sugar maple root respiration in experimentally warmed soil.

PubMed

Jarvi, Mickey P; Burton, Andrew J

2013-09-01

The response of root respiration to warmer soil can affect ecosystem carbon (C) allocation and the strength of positive feedbacks between climatic warming and soil CO2 efflux. This study sought to determine whether fine-root (<1 mm) respiration in a sugar maple (Acer saccharum Marsh.)-dominated northern hardwood forest would adjust to experimentally warmed soil, reducing C return to the atmosphere at the ecosystem scale to levels lower than that would be expected using an exponential temperature response function. Infrared heating lamps were used to warm the soil (+4 to +5 °C) in a mature sugar maple forest in a fully factorial design, including water additions used to offset the effects of warming-induced dry soil. Fine-root-specific respiration rates, root biomass, root nitrogen (N) concentration, soil temperature and soil moisture were measured from 2009 to 2011, with experimental treatments conducted from late 2010 to 2011. Partial acclimation of fine-root respiration to soil warming occurred, with soil moisture deficit further constraining specific respiration rates in heated plots. Fine-root biomass and N concentration remained unchanged. Over the 2011 growing season, ecosystem root respiration was not significantly greater in warmed soil. This result would not be predicted by models that allow respiration to increase exponentially with temperature and do not directly reduce root respiration in drier soil.

Does species richness affect fine root biomass and production in young forest plantations?

PubMed

Domisch, Timo; Finér, Leena; Dawud, Seid Muhie; Vesterdal, Lars; Raulund-Rasmussen, Karsten

2015-02-01

Tree species diversity has been reported to increase forest ecosystem above-ground biomass and productivity, but little is known about below-ground biomass and production in diverse mixed forests compared to single-species forests. For testing whether species richness increases below-ground biomass and production and thus complementarity between forest tree species in young stands, we determined fine root biomass and production of trees and ground vegetation in two experimental plantations representing gradients in tree species richness. Additionally, we measured tree fine root length and determined species composition from fine root biomass samples with the near-infrared reflectance spectroscopy method. We did not observe higher biomass or production in mixed stands compared to monocultures. Neither did we observe any differences in tree root length or fine root turnover. One reason for this could be that these stands were still young, and canopy closure had not always taken place, i.e. a situation where above- or below-ground competition did not yet exist. Another reason could be that the rooting traits of the tree species did not differ sufficiently to support niche differentiation. Our results suggested that functional group identity (i.e. conifers vs. broadleaved species) can be more important for below-ground biomass and production than the species richness itself, as conifers seemed to be more competitive in colonising the soil volume, compared to broadleaved species.

Effects of elevated CO2 on fine root biomass are reduced by aridity but enhanced by soil nitrogen: A global assessment.

PubMed

Piñeiro, Juan; Ochoa-Hueso, Raúl; Delgado-Baquerizo, Manuel; Dobrick, Silvan; Reich, Peter B; Pendall, Elise; Power, Sally A

2017-11-10

Plant roots play a crucial role in regulating key ecosystem processes such as carbon (C) sequestration and nutrient solubilisation. Elevated (e)CO 2 is expected to alter the biomass of fine, coarse and total roots to meet increased demand for other resources such as water and nitrogen (N), however, the magnitude and direction of observed changes vary considerably between ecosystems. Here, we assessed how climate and soil properties mediate root responses to eCO 2 by comparing 24 field-based CO 2 experiments across the globe including a wide range of ecosystem types. We calculated response ratios (i.e. effect size) and used structural equation modelling (SEM) to achieve a system-level understanding of how aridity, mean annual temperature and total soil nitrogen simultaneously drive the response of total, coarse and fine root biomass to eCO 2 . Models indicated that increasing aridity limits the positive response of fine and total root biomass to eCO 2 , and that fine (but not coarse or total) root responses to eCO 2 are positively related to soil total N. Our results provide evidence that consideration of factors such as aridity and soil N status is crucial for predicting plant and ecosystem-scale responses to future changes in atmospheric CO 2 concentrations, and thus feedbacks to climate change.

Water Uptake along the Length of Grapevine Fine Roots: Developmental anatomy, tissue specific aquaporin expression, and pathways of water transport

USDA-ARS?s Scientific Manuscript database

To better understand water uptake patterns in root systems of woody perennial crops, we detailed the developmental anatomy and hydraulic physiology along the length of grapevine fine roots- from the tip to secondary growth zones. Our characterization included localization of suberized structures an...

SEASONAL PATTERNS OF FINE ROOT PRODUCTION AND TURNOVER IN PONDEROSA PINE STANDS OF DIFFERENT AGES

EPA Science Inventory

Root minirhizotron tubes were installed in two ponderosa pine (Pinus ponderosa Laws.) stands around three different tree age classes (16, 45, and > 250 yr old) to examine root spatial distribution in relation to canopy size and tree distribution, and to determine if rates of fine...

Improving Simulations of Fine Dust Surface Concentrations over the Western United States by Optimizing the Particle Size Distribution

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

Zhang, Li; Kok, Jasper F.; Henze, Daven

2013-06-28

To improve estimates of remote contributions of dust to fine particulate matter (PM2.5) in the western United States, new dust particle size distributions (PSDs) based upon scale-invariant fragmentation theory (Kok_PSD) with constraints from in situ measurements (IMP_PSD) are implemented in a chemical transport model (GEOS-Chem). Compared to initial simulations, this leads to reductions in the mass of emitted dust particles with radii <1.8 mm by 40%-60%. Consequently, the root-mean-square error in simulated fine dust concentrations compared to springtime surface observations in the western United States is reduced by 67%-81%. The ratio of simulated fine to coarse PM mass is alsomore » improved, which is not achievable by reductions in total dust emissions. The IMP_PSD best represents the PSD of dust transported from remote sources and reduces modeled PM2.5 concentrations up to 5 mg/m3 over the western United States, which is important when considering sources contributing to nonattainment of air quality standards. Citation: Zhang, L., J. F. Kok, D. K. Henze, Q. Li, and C. Zhao (2013), Improving simulations of fine dust surface concentrations over the western United States by optimizing the particle size distribution, Geophys. Res. Lett., 40, 3270-3275, doi:10.1002/grl.50591.« less

Selection of root-zone media for higher plant cultivation in space.

PubMed

Guo, Shuang-sheng; Ai, Wei-dang; Zhao, Cheng-jian; Han, Li-jun; Wang, Jian-xiao

2004-04-01

To investigate the cultivating effects of several mineral matters used as root-zone media for higher plant growth in space. Four kinds of artificial and natural mineral matters were used as plant root-zone media based on lots of investigation and analysis. Nutrient liquid was delivered into the media by a long capillary material, and roots of plants obtained nutrition and water from the media. The related parameters such as plant height and photosynthetic efficiency were measured and analyzed. The growing effect in a mixture of coarse and fine ceramic particles with equal quantity proportion was the best, that in fine ceramic particles was the second best, that in clinoptilolite particles was the third and that in diorite particles was the last. The mixture of coarse and fine ceramic particles with equal quantity possesses not only fine capillary action, but also good aerating ability, and therefore is capable of being utilized as an effective root-zone media for higher plants intended to be grown in space.

Fine root morphological adaptations in Scots pine, Norway spruce and silver birch along a latitudinal gradient in boreal forests.

PubMed

Ostonen, Ivika; Lõhmus, Krista; Helmisaari, Heljä-Sisko; Truu, Jaak; Meel, Signe

2007-11-01

Variability in short root morphology of the three main tree species of Europe's boreal forest (Norway spruce (Picea abies L. Karst.), Scots pine (Pinus sylvestris L.) and silver birch (Betula pendula Roth)) was investigated in four stands along a latitudinal gradient from northern Finland to southern Estonia. Silver birch and Scots pine were present in three stands and Norway spruce was present in all stands. For three fertile Norway spruce stands, fine root biomass and number of root tips per stand area or unit basal area were assessed from north to south. Principal component analysis indicated that short root morphology was significantly affected by tree species and site, which together explained 34.7% of the total variability. The range of variation in mean specific root area (SRA) was 51-74, 60-70 and 84-124 m(2) kg(-1) for Norway spruce, Scots pine and silver birch, respectively, and the corresponding ranges for specific root length were 37-47, 40-48 and 87-97 m g(-1). The range of variation in root tissue density of Norway spruce, Scots pine and silver birch was 113-182, 127-158 and 81-156 kg m(-3), respectively. Sensitivity of short root morphology to site conditions decreased in the order: Norway spruce > silver birch > Scots pine. Short root SRA increased with site fertility in all species. In Norway spruce, fine root biomass and number of root tips per m(2) decreased from north to south. The differences in morphological parameters among sites were significant but smaller than the site differences in fine root biomass and number of root tips.

Relationships between fine root dynamics and nitrogen availability in Michigan northern hardwood forests

Treesearch

A. J. Burton; K. S. Pregitzer; R. L. Hendrick

2000-01-01

Minirhizotrons were used to observe fine root (≤1 mm) production, mortality, and longevity over 2 years in four sugar-maple-dominated northern hardwood forests located along a latitudinal temperature gradient. The sites also differed in N availability, allowing us to assess the relative influences of soil temperature and N availability in controlling fine...

Leaf and fine root carbon stocks and turnover are coupled across Arctic ecosystems.

PubMed

Sloan, Victoria L; Fletcher, Benjamin J; Press, Malcolm C; Williams, Mathew; Phoenix, Gareth K

2013-12-01

Estimates of vegetation carbon pools and their turnover rates are central to understanding and modelling ecosystem responses to climate change and their feedbacks to climate. In the Arctic, a region containing globally important stores of soil carbon, and where the most rapid climate change is expected over the coming century, plant communities have on average sixfold more biomass below ground than above ground, but knowledge of the root carbon pool sizes and turnover rates is limited. Here, we show that across eight plant communities, there is a significant positive relationship between leaf and fine root turnover rates (r(2) = 0.68, P < 0.05), and that the turnover rates of both leaf (r(2) = 0.63, P < 0.05) and fine root (r(2) = 0.55, P < 0.05) pools are strongly correlated with leaf area index (LAI, leaf area per unit ground area). This coupling of root and leaf dynamics supports the theory of a whole-plant economics spectrum. We also show that the size of the fine root carbon pool initially increases linearly with increasing LAI, and then levels off at LAI = 1 m(2) m(-2), suggesting a functional balance between investment in leaves and fine roots at the whole community scale. These ecological relationships not only demonstrate close links between above and below-ground plant carbon dynamics but also allow plant carbon pool sizes and their turnover rates to be predicted from the single readily quantifiable (and remotely sensed) parameter of LAI, including the possibility of estimating root data from satellites. © 2013 John Wiley & Sons Ltd.

ASSESSING THE EFFECTS OF GLOBAL CLIMATE CHANGE ON THE PRODUCTION AND MORTALITY OF DOUGLAS FIR FINE ROOTS USING MINIRHIZOTRONS

EPA Science Inventory

Fine roots (roots 2 mm in diameter) are one of the principal absorptive surfaces for water and nutrients in terrestrial plants. As such they are vital for plant growth and survival, while their turnover serves as a primary mechanism for carbon addition to soil. Little is known...

The outcome of ecosystem manipulation by elevating atmospheric CO2 is influenced by tree identity and mixture

NASA Astrophysics Data System (ADS)

Godbold, Douglas; Smith, Andrew; Lukac, Martin

2013-04-01

Free Air Carbon dioxide Enrichment (FACE) has often been used predict the response of forest ecosystems to a future high CO2 world. Many of these investigations have been restricted to exposure of single species or genotypes to elevated CO2. To investigate the interaction between tree mixture and elevated CO2, Alnus glutinosa, Betula pendula and Fagus sylvatica were planted in areas of single species and a three species polyculture in a free-air CO2 enrichment study (BangorFACE). The trees were exposed to ambient or elevated CO2 for 4 years. Aboveground woody biomass was increased in polyculture under both ambient and elevated CO2, but the response to elevated CO2 was smaller in polyculture than in the monocultures. In some years, a longer leaf retention was shown under high CO2, and is an indication that environmental factors may moderate tree response to high CO2. Fine and coarse root biomass, together with fine root turnover and fine root morphological characteristics were also measured. Fine root biomass and morphology responded differentially to the elevated CO2 at different soil depths in the three species when grown in monocultures. In polyculture, a greater response to elevated CO2 was observed in coarse roots, and fine root area index. Total fine root biomass was positively affected by elevated CO2 at the end of the experiment, but not by species diversity. Our results show that the aboveground and belowground response to elevated CO2 is significantly affected by intra- and inter-specific competition, and that elevated CO2 response may be reduced in forest communities comprised of tree species with contrasting functional traits but also that other environmental factors may induce previously unseen effects.

Exploring the transfer of recent plant photosynthates to soil microbes: mycorrhizal pathway vs direct root exudation

PubMed Central

Kaiser, Christina; Kilburn, Matt R; Clode, Peta L; Fuchslueger, Lucia; Koranda, Marianne; Cliff, John B; Solaiman, Zakaria M; Murphy, Daniel V

2015-01-01

Plants rapidly release photoassimilated carbon (C) to the soil via direct root exudation and associated mycorrhizal fungi, with both pathways promoting plant nutrient availability. This study aimed to explore these pathways from the root's vascular bundle to soil microbial communities. Using nanoscale secondary ion mass spectrometry (NanoSIMS) imaging and 13C-phospho- and neutral lipid fatty acids, we traced in-situ flows of recently photoassimilated C of 13CO2-exposed wheat (Triticum aestivum) through arbuscular mycorrhiza (AM) into root- and hyphae-associated soil microbial communities. Intraradical hyphae of AM fungi were significantly 13C-enriched compared to other root-cortex areas after 8 h of labelling. Immature fine root areas close to the root tip, where AM features were absent, showed signs of passive C loss and co-location of photoassimilates with nitrogen taken up from the soil solution. A significant and exclusively fresh proportion of 13C-photosynthates was delivered through the AM pathway and was utilised by different microbial groups compared to C directly released by roots. Our results indicate that a major release of recent photosynthates into soil leave plant roots via AM intraradical hyphae already upstream of passive root exudations. AM fungi may act as a rapid hub for translocating fresh plant C to soil microbes. PMID:25382456

Regional scale patterns of fine root lifespan and turnover under current and future climate

Treesearch

M. Luke McCormack; David M. Eissenstat; Anantha M. Prasad; Erica A. Smithwick

2013-01-01

Fine root dynamics control a dominant flux of carbon from plants and into soils and mediate potential uptake and cycling of nutrients and water in terrestrial ecosystems. Understanding of these patterns is needed to accurately describe critical processes like productivity and carbon storage from ecosystem to global scales. However, limited observations of root dynamics...

Effects of spatiotemporal variation of soil salinity on fine root distribution in different plant configuration modes in new reclamation coastal saline field.

PubMed

Jiang, Hong; Du, Hongyu; Bai, Yingying; Hu, Yue; Rao, Yingfu; Chen, Chong; Cai, Yongli

2016-04-01

In order to study the effects of salinity on plant fine roots, we considered three different plant configuration modes (tree stand model (TSM), shrub stand model (SSM), and tree-shrub stand model (TSSM)). Soil samples were collected with the method of soil drilling. Significant differences of electrical conductivity (EC) in the soil depth of 0-60 cm were observed among the three modes (p < 0.05). In the above three modes, the variation of soil salinity among various soil layers and monthly variation of soil salinity were the highest in SSM and reached 2.30 and 2.23 mS/cm (EC1:5), respectively. Due to the effect of salinity, fine root biomass (FRB) showed significant differences in different soil depths (p < 0.05). More than 60% of FRB was concentrated in the soil depth above 30 cm. FRB showed exponential decline with soil depth (p < 0.05). FRB showed spatial heterogeneity in the 40-cm soil depth. In the above three modes, compared with FRB, specific root length (SRL) and fine root length density (FRLD) showed the similar changing trend. Fine roots showed significant seasonal differences among different modes (p < 0.05). FRB showed the bimodal variation and was the highest in July. However, we found that the high content of salts had obvious inhibitory effect on the distribution of FRB. Therefore, the salinity should be below 1.5 mS/cm, which was suitable for the growth of plant roots. Among the three modes, TSSM had the highest FRB, SRL, and FRLD and no obvious soil salt accumulation was observed. The results indicated that fine root biomass was affected by high salt and that TSSM had the strong effects of salt suppression and control. In our study, TSSM may be the optimal configuration mode for salt suppression and control in saline soil.

3D Electrical Resistivity Tomography and Mise-à-la-Masse Method as Tools for the Characterization of Vine Roots

NASA Astrophysics Data System (ADS)

Boaga, J.; Mary, B.; Peruzzo, L.; Schmutz, M.; Wu, Y.; Hubbard, S. S.; Cassiani, G.

2017-12-01

The interest on non-invasive geophysical monitoring of soil properties and root architecture is rapidly growing. Despite this, few case studies exist concerning vineyards, which are economically one of the leading sectors of agriculture. In this study, we integrate different geophysical methods in order to gain a better imaging of the vine root system, with the aim of quantifying root development, a key factor to understand roots-soil interaction and water balance. Our test site is a vineyard located in Bordeaux (France), where we adopted the Mise-a-la-Masse method (MALM) and micro-scale electrical resistivity tomography (ERT) on the same 3D electrode configuration. While ERT is a well-established technique to image changes in soil moisture content by root activity, MALM is a relatively new approach in this field of research. The idea is to inject current directly in the plant trunk and verify the resulting voltage distribution in the soil, as an effect of current distribution through the root system. In order to distinguish the root effect from other phenomena linked to the soil heterogeneities, we conducted and compared MALM measurements acquired through injecting current into the stem and into the soil near the stem. Moreover, the MALM data measured in the field were compared with numerical simulations to improve the confidence in the interpretation. Differences obtained between the stem and soil injection clearly validated the assumption that the whole root system is acting as a current pathway, thus highlighting the locations at depth where current is entering the soil from the fine roots. The simulation results indicated that the best fit is obtained through considering distributed sources with depth, reflecting a probable root zone area. The root location and volume estimated using this procedure are in agreement with vineyard experimental evidence. This work suggests the promising application of electrical methods to locate and monitor root systems. Further work is necessary to effectively integrate the geophysical and plant physiology information.

ARBUSCULAR MYCORRHIZAL COLONIZATION OF LARREA TRIDENTATA AND AMBROSIA DUMOSA ROOTS VARIES WITH PRECIPITATION AND SEASON IN THE MOJAVE DESERT

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

M. E. APPLE; C. I. THEE; V. L. SMITH-LONGOZO

2004-01-01

The percentage of fine roots colonized by arbuscular mycorrhizal (AM) fungi varied with season and with species in the co-dominant shrubs Lurreu tridentutu and Ambrosia dumosu at a site adjacent to the Nevada Desert FACE (Free-Air CO{sub 2} Enrichment) Facility (NDFF) in the Mojave Desert. We excavated downward and outward from the shrub bases in both species to collect and examine fine roots (< 1.0 mm diameter) at monthly intervals throughout 2001 and from October 2002 to September 2003. Fungal structures became visible in cleared roots stained with trypan blue. We quantified the percent colonization of roots by AM fungimore » via the line intercept method. In both years and for both species, colonization was highest in fall, relatively low in spring when root growth began, increased in late spring, and decreased during summer drought periods. Increases in colonization during summer and fall reflect corresponding increases in precipitation. Spring mycorrhizal colonization is low despite peaks in soil water availability and precipitation, indicating that precipitation is not the only factor influencing mycorrhizal colonization. Because the spring decrease in mycorrhizal colonization occurs when these shrubs initiate a major flush of fine root growth, other phenological events such as competing demands for carbon by fine root initiation, early season shoot growth, and flowering may reduce carbon availability to the fungus, and hence decrease colonization. Another possibility is that root growth exceeds the rate of mycorrhizal colonization.« less

[Effects of neighbor competition on growth, fine root morphology and distribution of Schima superba and Cunninghamia lanceolata in different nutrient environments].

PubMed

Yao, Jia Bao; Chu, Xiu Li; Zhou, Zhi Chun; Tong, Jian She; Wang, Hui; Yu, Jia Zhong

2017-05-18

Taking Schima superba and Cunninghamia lanceolata as test materials, a pot experiment was conducted to simulate the heterogeneous and homogeneous forest soil nutrient environments, and design three planting modes including single plant, two-strain pure plant and two-strain mixed ones to reason the promotion in mixed S. superba and C. lanceolata plantation and the competitive advantage of S. superba. Results showed that compared with the homogeneous nutrient environment, both S. superba and C. lanceolata had the higher seedling height and dry matter accumulation, when mixed in the heterogeneous nutrient environment, S. superba displayed the obviously competitive advantage, which related to its root plasticity. The fine root of S. superba mixed in each diameter class showed a lot of hyperplasia, and the root total length, surface area and volume of which were 80%-180% higher than that of C. lanceolata. S. superba took the advantage of the compensatory growth strategy of vertical direction in fine roots, namely, they still multiplied to gain greater competitive advantage in low nutrient patches, besides occupying eutrophic surface. The different soil colonization and niche differentiation in fine root of S. superba and C. lanceolata alleviated the strong competition for nutrients of the roots of the two species, and improved the mixed-plantation production. Pure plantation of S. superba harvested the lower yield, which due to the root self-recognition inhibited the growth of root system. Fine roots staggered and evenly distributed on the space might be a reason for stable structure of pure S. superba plantation. So, it was recommended that block surface layer soil preparation and fertilization are used to improve the soil nutrient distribution, and the mixed plantation is constructed to promote the growth of S. superba and C. lanceolata, at the same time, the stand density is regulated to promote tree growth for the pure artificial S. superba plantation which had already been built.

Applicability of optical scanner method for fine root dynamics

NASA Astrophysics Data System (ADS)

Kume, Tomonori; Ohashi, Mizue; Makita, Naoki; Khoon Kho, Lip; Katayama, Ayumi; Matsumoto, Kazuho; Ikeno, Hidetoshi

2016-04-01

Fine root dynamics is one of the important components in forest carbon cycling, as ~60 % of tree photosynthetic production can be allocated to root growth and metabolic activities. Various techniques have been developed for monitoring fine root biomass, production, mortality in order to understand carbon pools and fluxes resulting from fine roots dynamics. The minirhizotron method is now a widely used technique, in which a transparent tube is inserted into the soil and researchers count an increase and decrease of roots along the tube using images taken by a minirhizotron camera or minirhizotron video camera inside the tube. This method allows us to observe root behavior directly without destruction, but has several weaknesses; e.g., the difficulty of scaling up the results to stand level because of the small observation windows. Also, most of the image analysis are performed manually, which may yield insufficient quantitative and objective data. Recently, scanner method has been proposed, which can produce much bigger-size images (A4-size) with lower cost than those of the minirhizotron methods. However, laborious and time-consuming image analysis still limits the applicability of this method. In this study, therefore, we aimed to develop a new protocol for scanner image analysis to extract root behavior in soil. We evaluated applicability of this method in two ways; 1) the impact of different observers including root-study professionals, semi- and non-professionals on the detected results of root dynamics such as abundance, growth, and decomposition, and 2) the impact of window size on the results using a random sampling basis exercise. We applied our new protocol to analyze temporal changes of root behavior from sequential scanner images derived from a Bornean tropical forests. The results detected by the six observers showed considerable concordance in temporal changes in the abundance and the growth of fine roots but less in the decomposition. We also examined potential errors due to window size in the temporal changes in abundance and growth using the detected results, suggesting high applicability of the scanner methods with wide observation windows.

Fine root biomass, necromass and chemistry during seven years of elevated aluminium concentrations in the soil solution of a middle-aged Picea abies stand.

PubMed

Eldhuset, Toril D; Lange, Holger; de Wit, Helene A

2006-10-01

Toxic effects of aluminium (Al) on Picea abies (L.) Karst. (Norway spruce) trees are well documented in laboratory-scale experiments, but field-based evidence is scarce. This paper presents results on fine root growth and chemistry from a field manipulation experiment in a P. abies stand that was 45 years old when the experiment started in 1996. Different amounts of dissolved aluminium were added as AlCl3 by means of periodic irrigation during the growing season in the period 1997-2002. Potentially toxic concentrations of Al in the soil solution were obtained. Fine roots were studied from direct cores (1996) and sequential root ingrowth cores (1999, 2001, 2002) in the mineral soil (0-40 cm). We tested two hypotheses: (1) elevated concentration of Al in the root zone leads to significant changes in root biomass, partitioning into fine, coarse, living or dead fractions, and distribution with depth; (2) elevated Al concentration leads to a noticeable uptake of Al and reduced uptake of Ca and Mg; this results in Ca and Mg depletion in roots. Hypothesis 1 was only marginally supported, as just a few significant treatment effects on biomass were found. Hypothesis 2 was supported in part; Al addition led to increased root concentrations of Al in 1999 and 2002 and reduced Mg/Al in 1999. Comparison of roots from subsequent root samplings showed a decrease in Al and S over time. The results illustrated that 7 years of elevated Al(tot) concentrations in the soil solution up to 200 microM are not likely to affect root growth. We also discuss possible improvements of the experimental approach.

OPTIMIZING MINIRHIZOTRON SAMPLE FREQUENCY FOR AN EVERGREEN AND DECIDIOUS TREE SPECIES

EPA Science Inventory

Increasingly minirhizotrons are being used in natural ecosystems to determine fine root production and turnover, as they provide a nondestructive, in situ method for studying fine root dynamics. Our objective is to determine how image collection frequency influences estimates of ...

Contribution of fine tree roots to the silicon cycle in a temperate forest ecosystem developed on three soil types

NASA Astrophysics Data System (ADS)

Turpault, Marie-Pierre; Calvaruso, Christophe; Kirchen, Gil; Redon, Paul-Olivier; Cochet, Carine

2018-04-01

The role of forest vegetation in the silicon (Si) cycle has been widely examined. However, to date, little is known about the specific role of fine roots. The main objective of our study was to assess the influence of fine roots on the Si cycle in a temperate forest in north-eastern France. Silicon pools and fluxes in vegetal solid and solution phases were quantified within each ecosystem compartment, i.e. in the atmosphere, above-ground and below-ground tree tissues, forest floor and different soil layers, on three plots, each with different soil types, i.e. Dystric Cambisol (DC), Eutric Cambisol (EC) and Rendzic Leptosol (RL). In this study, we took advantage of a natural soil gradient, from shallow calcic soil to deep moderately acidic soil, with similar climates, atmospheric depositions, species compositions and management. Soil solutions were measured monthly for 4 years to study the seasonal dynamics of Si fluxes. A budget of dissolved Si (DSi) was also determined for the forest floor and soil layers. Our study highlighted the major role of fine roots in the Si cycle in forest ecosystems for all soil types. Due to the abundance of fine roots mainly in the superficial soil layers, their high Si concentration (equivalent to that of leaves and 2 orders higher than that of coarse roots) and their rapid turnover rate (approximately 1 year), the mean annual Si fluxes in fine roots in the three plots were 68 and 110 kg ha-1 yr-1 for the RL and the DC, respectively. The turnover rates of fine roots and leaves were approximately 71 and 28 % of the total Si taken up by trees each year, demonstrating the importance of biological recycling in the Si cycle in forests. Less than 1 % of the Si taken up by trees each year accumulated in the perennial tissues. This study also demonstrated the influence of soil type on the concentration of Si in the annual tissues and therefore on the Si fluxes in forests. The concentrations of Si in leaves and fine roots were approximately 1.5-2.0 times higher in the Si-rich DC compared to the Si-poor RL. In terms of the DSi budget, DSi production was large in the three plots in the forest floor (9.9 to 12.7 kg ha-1 yr-1), as well as in the superficial soil layer (5.3 to 14.5 kg ha-1 yr-1), and decreased with soil depth. An immobilization of DSi was even observed at 90 cm depth in plot DC (-1.7 kg ha-1 yr-1). The amount of Si leached from the soil profile was relatively low compared to the annual uptake by trees (13 % in plot DC to 29 % in plot RL). The monthly measurements demonstrated that the seasonal dynamics of the DSi budget were mainly linked to biological activity. Notably, the peak of dissolved Si production in the superficial soil layer occurred during winter and probably resulted from fine-root decomposition. Our study reveals that biological processes, particularly those involving fine roots, play a predominant role in the Si cycle in temperate forest ecosystems, while the geochemical processes appear to be limited.

Root productivity of deciduous and evergreen species identified using a molecular approach

NASA Astrophysics Data System (ADS)

Ellsworth, P.; Sternberg, L. O.

2012-12-01

The linkage between leaf traits and root structure may explain how plants integrate above and belowground traits into whole plant adaptations to environmental stresses. In dry seasonal forests, the lack of dry season precipitation dries out the relatively nutrient-rich shallow soil, leaving shallow soil water and nutrients inaccessible to uptake until the wet season. In tropical or subtropical seasonal dry forests, deciduousness may allow for the survival of shallow fine roots during the dry season. Losing leaves during the dry season reduces aboveground plant water demand, and a greater proportion of water extracted from deep soil can be used to maintain shallow roots until the wet season. Higher shallow root survival through the dry season than evergreen species means that deciduous species can take advantage of the nutrient pulse associated with the onset of the wet season. To test the above hypothesis, fine roots were collected from soil cores in a seasonally dry forest during the dry season, onset of the wet season, and the wet season and were identified to selected evergreen and deciduous study species. The fine roots of two of the selected species (Lyonia ferruginea and Carya floridana) could be identified from visual characteristics. The other three study species, which were all from the genus Quercus (Q. geminata, Q. myrtifolia, and Q. laevis), were impossible to separate visually. We developed a PCR-based restriction fragment length polymorphism (PCR-RFLP) technique, which provided a quick, simple, low-cost way to identify the species of all fine roots of our study species. We extracted DNA from all roots that were not visually identified, amplified the internal transcribed spacer region (ITS), digested the ITS region with the restriction enzyme TaqαI, and used gel electrophoresis to separate DNA fragments. Using a PCR-RFLP based root identification key that we developed for the species at Archbold Biological Station, all species that could not be identified visually were separated based on each species ' unique banding pattern of restriction fragments. Approximately 2,500 roots were identified using PCR-RFLP and approximately 1,500 more roots were identified visually. Identifying fine roots to species allows for species-level analysis of root productivity in this in situ study.

Growth of plant root cultures in liquid- and gas-dispersed reactor environments.

PubMed

McKelvey, S A; Gehrig, J A; Hollar, K A; Curtis, W R

1993-01-01

The growth of Agrobacterium transformed "hairy root" cultures of Hyoscyamus muticus was examined in various liquid- and gas-dispersed bioreactor configurations. Reactor runs were replicated to provide statistical comparisons of nutrient availability on culture performance. Accumulated tissue mass in submerged air-sparged reactors was 31% of gyratory shake-flask controls. Experiments demonstrate that poor performance of sparged reactors is not due to bubble shear damage, carbon dioxide stripping, settling, or flotation of roots. Impaired oxygen transfer due to channeling and stagnation of the liquid phase are the apparent causes of poor growth. Roots grown on a medium-perfused inclined plane grew at 48% of gyratory controls. This demonstrates the ability of cultures to partially compensate for poor liquid distribution through vascular transport of nutrients. A reactor configuration in which the medium is sprayed over the roots and permitted to drain down through the root tissue was able to provide growth rates which are statistically indistinguishable (95% T-test) from gyratory shake-flask controls. In this type of spray/trickle-bed configuration, it is shown that distribution of the roots becomes a key factor in controlling the rate of growth. Implications of these results regarding design and scale-up of bioreactors to produce fine chemicals from root cultures are discussed.

Auxin Controls Arabidopsis Adventitious Root Initiation by Regulating Jasmonic Acid Homeostasis[W

PubMed Central

Gutierrez, Laurent; Mongelard, Gaëlle; Floková, Kristýna; Păcurar, Daniel I.; Novák, Ondřej; Staswick, Paul; Kowalczyk, Mariusz; Păcurar, Monica; Demailly, Hervé; Geiss, Gaia; Bellini, Catherine

2012-01-01

Vegetative shoot-based propagation of plants, including mass propagation of elite genotypes, is dependent on the development of shoot-borne roots, which are also called adventitious roots. Multiple endogenous and environmental factors control the complex process of adventitious rooting. In the past few years, we have shown that the auxin response factors ARF6 and ARF8, targets of the microRNA miR167, are positive regulators of adventitious rooting, whereas ARF17, a target of miR160, is a negative regulator. We showed that these genes have overlapping expression profiles during adventitious rooting and that they regulate each other’s expression at the transcriptional and posttranscriptional levels by modulating the homeostasis of miR160 and miR167. We demonstrate here that this complex network of transcription factors regulates the expression of three auxin-inducible Gretchen Hagen3 (GH3) genes, GH3.3, GH3.5, and GH3.6, encoding acyl-acid-amido synthetases. We show that these three GH3 genes are required for fine-tuning adventitious root initiation in the Arabidopsis thaliana hypocotyl, and we demonstrate that they act by modulating jasmonic acid homeostasis. We propose a model in which adventitious rooting is an adaptive developmental response involving crosstalk between the auxin and jasmonate regulatory pathways. PMID:22730403

The allocation of ecosystem net primary productivity in tropical forests

PubMed Central

Malhi, Yadvinder; Doughty, Christopher; Galbraith, David

2011-01-01

The allocation of the net primary productivity (NPP) of an ecosystem between canopy, woody tissue and fine roots is an important descriptor of the functioning of that ecosystem, and an important feature to correctly represent in terrestrial ecosystem models. Here, we collate and analyse a global dataset of NPP allocation in tropical forests, and compare this with the representation of NPP allocation in 13 terrestrial ecosystem models. On average, the data suggest an equal partitioning of allocation between all three main components (mean 34 ± 6% canopy, 39 ± 10% wood, 27 ± 11% fine roots), but there is substantial site-to-site variation in allocation to woody tissue versus allocation to fine roots. Allocation to canopy (leaves, flowers and fruit) shows much less variance. The mean allocation of the ecosystem models is close to the mean of the data, but the spread is much greater, with several models reporting allocation partitioning outside of the spread of the data. Where all main components of NPP cannot be measured, litterfall is a good predictor of overall NPP (r2 = 0.83 for linear fit forced through origin), stem growth is a moderate predictor and fine root production a poor predictor. Across sites the major component of variation of allocation is a shifting allocation between wood and fine roots, with allocation to the canopy being a relatively invariant component of total NPP. This suggests the dominant allocation trade-off is a ‘fine root versus wood’ trade-off, as opposed to the expected ‘root–shoot’ trade-off; such a trade-off has recently been posited on theoretical grounds for old-growth forest stands. We conclude by discussing the systematic biases in estimates of allocation introduced by missing NPP components, including herbivory, large leaf litter and root exudates production. These biases have a moderate effect on overall carbon allocation estimates, but are smaller than the observed range in allocation values across sites. PMID:22006964

Effects of warming on ectomycorrhizal colonization and nitrogen nutrition of Picea asperata seedlings grown in two contrasting forest ecosystems

PubMed Central

Li, Yuejiao; Sun, Didi; Li, Dandan; Xu, Zhenfeng; Zhao, Chunzhang; Lin, Honghui; Liu, Qing

2015-01-01

Ectomycorrhiza (ECM) plays an important role in plant nitrogen (N) nutrition and regulates plant responded to climate warming. We conducted a field experiment in a natural forest and a plantation in the eastern Tibetan Plateau to estimate the warming effects of open-top chambers (OTC) on ECM and N nutrition of Picea asperata seedlings. Four-year warming significantly decreased ECM colonization, ECM fungal biomass, fine root vigor, and the N concentration of leaf, stem and coarse root, but significantly increased fine root N concentration and N content of leaf, stem, fine root and whole plant in natural forest. Contrarily, warming induced no obvious change in most of these parameters in plantation. Moreover, warming decreased rhizospheric soil inorganic N content in both forests. Our results showed that four-year warming was not beneficial for ECM colonization of P. asperata seedlings in the two forests, and the seedlings in natural forest were more sensitive and flexible to experimental warming than in plantation. The changes of ECM colonization and fine root biomass for effective N uptake would be good for plant growth and remit N leaching under future warming in natural forest. PMID:26655633

ESTIMATES OF DOUGLAS-FIR FINE ROOT PRODUCTION AND MORTALITY FROM MINIRHIZOTRONS

EPA Science Inventory

Minirhizotrons were used to assess the influence of soil resources on fine root (diameter < 2 mm) production, mortality, and standing crop over a two-year period. Two study sites were located, along an elevational transect, in the Oregon Cascade Mountains in mature (> 100 years o...

Fine root respiration in mature eastern white pine (Pinus strobus) in situ: the importance of CO2 in controlled environments.

Treesearch

Barton D. Clinton; James M. Vose

1999-01-01

Clinton and Vose measured seasonal fine root respiration rate in situ while controlling chamber temperature and [CO2]. Atmospheric and [CO2] ([CO2]a) and measured soil [CO2] ([CO2]s) were alternately delivered...

Coupling fine-scale root and canopy structure using ground-based remote sensing

Treesearch

Brady Hardiman; Christopher Gough; John Butnor; Gil Bohrer; Matteo Detto; Peter Curtis

2017-01-01

Ecosystem physical structure, defined by the quantity and spatial distribution of biomass, influences a range of ecosystem functions. Remote sensing tools permit the non-destructive characterization of canopy and root features, potentially providing opportunities to link above- and belowground structure at fine spatial resolution in...

Legacy effects of land-use modulate tree growth responses to climate extremes.

PubMed

Mausolf, Katharina; Härdtle, Werner; Jansen, Kirstin; Delory, Benjamin M; Hertel, Dietrich; Leuschner, Christoph; Temperton, Vicky M; von Oheimb, Goddert; Fichtner, Andreas

2018-05-10

Climate change can impact forest ecosystem processes via individual tree and community responses. While the importance of land-use legacies in modulating these processes have been increasingly recognised, evidence of former land-use mediated climate-growth relationships remain rare. We analysed how differences in former land-use (i.e. forest continuity) affect the growth response of European beech to climate extremes. Here, using dendrochronological and fine root data, we show that ancient forests (forests with a long forest continuity) and recent forests (forests afforested on former farmland) clearly differ with regard to climate-growth relationships. We found that sensitivity to climatic extremes was lower for trees growing in ancient forests, as reflected by significantly lower growth reductions during adverse climatic conditions. Fine root morphology also differed significantly between the former land-use types: on average, trees with high specific root length (SRL) and specific root area (SRA) and low root tissue density (RTD) were associated with recent forests, whereas the opposite traits were characteristic of ancient forests. Moreover, we found that trees of ancient forests hold a larger fine root system than trees of recent forests. Our results demonstrate that land-use legacy-mediated modifications in the size and morphology of the fine root system act as a mechanism in regulating drought resistance of beech, emphasising the need to consider the 'ecological memory' of forests when assessing or predicting the sensitivity of forest ecosystems to global environmental change.

Using chloride and chlorine-36 as soil-water tracers to estimate deep percolation at selected locations on the U.S. Department of Energy Hanford site, Washington

USGS Publications Warehouse

Prych, Edmund A.

1995-01-01

Long-term average deep-percolation rates of water from precipitation on the U.S. Department of Energy Hanford Site in semiarid south-central Washington, as estimated by a chloride mass-balance method, range from 0.008 to 0.30 mm/yr (millimeters per year) at nine locations covered by a variety of fine-grain soils and vegetated with sagebrush and other deep-rooted plants plus sparse shallow-rooted grasses. Deep-percolation rates estimated using a chlorine-36 bomb-pulse method at three of the nine locations range from 2.1 to 3.4 mm/yr. Because the mass-balance method may underestimate percolation rates and the bomb-pulse method probably overestimates percolation rates, estimates by the two methods probably bracket actual rates. These estimates, as well as estimates by previous investigators who used different methods, are a small fraction of mean annual precipitation, which ranges from about 160 to 210 mm/yr at the different test locations. Estimates by the mass-balance method at four locations in an area that is vegetated only with sparse shallow-rooted grasses range from 0.39 to 2.0 mm/yr. Chlorine-36 data at one location in this area were sufficient only to determine that the upper limit of deep percolation is more than 5.1 mm/yr. Although estimates for locations in this area are larger than the estimates for locations with deep-rooted plants, they are at the lower end of the range of estimates for this area made by previous investigators.

EFFECTS OF ELEVATED CO2 ON FINE ROOT DYNAMICS IN A MOJAVE DESERT COMMUNITY: A FACE STUDY

EPA Science Inventory

Fine roots ('1 mm diameter) are critical in plant water and nutrient absorption, and it is important to understand how rising atmospheric CO2 will affect them as part of terrestrial ecosystem responses to global change. This study's objective was to determine the effects of elev...

Fine-Root Ecology Database (FRED): A Global Collection of Root Trait Data with Coincident Site, Vegetation, Edaphic, and Climatic Data, Version 1

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

Iversen, C. M.; Powell, A. S.; McCormack, M. L.

To address the need for a centralized root trait database, we are compiling the Fine-Root Ecology Database (FRED) from published literature and unpublished data. FRED Version 1 (FRED 1.0) currently houses more than 70,000 observations of root traits and their associated site, vegetation, edaphic, and climatic conditions from across the globe (see image below, which shows the more than 1000 distinct locations associated with observations in FRED 1.0). Data collection is ongoing and will continue for the foreseeable future. The more than 300 root traits currently housed in FRED 1.0 are described in detail here. FRED is focused on finemore » roots (less than 2 mm), as coarse roots are studied using different methodology, often at very different scales, and have different traits and trait interpretations.« less

[Response of fine roots to soil nutrient spatial heterogeneity].

PubMed

Wang, Qingcheng; Cheng, Yunhuan

2004-06-01

The spatial heterogeneity is the complexity and variation of systems or their attributes, and the heterogeneity of soil nutrients is ubiquitous in all natural ecosystems. The scale of spatial heterogeneity varies considerably among different ecosystems, from tens of centimeters to hundred meters. Some of the scales can be detected by individual plant. Because the growth of individual plants can be strongly influenced by soil heterogeneity, it follows that the inter-specific competition should also be affected. During the long process of evolution, plants developed various plastic responses with their root system, including morphological, physiological and mycorrhizal plasticity, to maximize the nutrient acquisition from heterogeneous soil resources. Morphological plasticity, an adjustment in root system spatial allocation and architecture in response to spatial heterogeneous distribution of available soil resources, has been most intensively studied, and root proliferation in nutrient rich patches has been certified for many species. The species that do respond may have an increased rate of nutrient uptake, leading to a competitive advantage. Scale and precision are two important features employed in describing the size and foraging behavior of root system. It was hypothesized that scale and precision is negatively related, i. e., the species with high scale of root system tend to be a less precise forager. The outcomes of different research work have been diverse, far from reaching a consensus. Species with high scale are not necessarily less precise in fine root allocation, and vice versa. The proliferation of fine root in enriched micro-sites is species dependent, and also affected by other factors, such as patch attributes (size and nutrients concentration), nutrients, and overall soil fertility. Beside root proliferation in nutrient enriched patches, plants can also adapt themselves to the heterogeneous soil environment by altering other root characteristics such as fine root diameter, branch angle, length, and spatial architecture of root system. Physiological and mycorrhizal plasticity can add some influence on the morphological plasticity to some extent, but they are less studied. Roots located in different patches can quickly regulate their nutrient uptake kinetics within different nutrient patches, and increase overall nutrient uptake. Physiological response may, to certain extent, reduce morphological response, and is meaningful for plant growth on soils with frequently changing spatial and temporal heterogeneity. Mycorrhizal plasticity has been least studied so far. Some researches revealed that mycorrhiza, rather than fine root, proliferated in enriched patches. But, it is not the case with other studies. The proliferation of mycorrhiza within enriched patches is more profitable in term of carbon invest. The effect of fine root proliferation on nutrient uptake is complex, depending on ion mobility and whether or not neighboring plant exists. The influence of root plasticity on the growth of plants is species specific. Some species (sensitive species) gain growth benefit, while others don't. The ability of an individual plant to response to heterogeneous resources has significant effect on its competitive ability and its fate within the community, and eventually shapes the composition and structure of the community.

Combining stable isotope and carbohydrate analyses in phloem sap and fine roots to study seasonal changes of source-sink relationships in a Mediterranean beech forest.

PubMed

Scartazza, Andrea; Moscatello, Stefano; Matteucci, Giorgio; Battistelli, Alberto; Brugnoli, Enrico

2015-08-01

Carbon isotope composition (δ(13)C) and carbohydrate content of phloem sap and fine roots were measured in a Mediterranean beech (Fagus sylvatica L.) forest throughout the growing season to study seasonal changes of source-sink relationships. Seasonal variations of δ(13)C and content of phloem sap sugars, collected during the daylight period, reflected the changes in soil and plant water status. The correlation between δ(13)C and content of phloem sap sugars, collected from plants belonging to different social classes, was significantly positive only during the driest month of July. In this month, δ(13)C of phloem sap sugars was inversely related to the increment of trunk radial growth and positively related to δ(13)C of fine roots. We conclude that the relationship between δ(13)C and the amount of phloem sap sugars is affected by a combination of causes, such as sink strength, tree social class, changes in phloem anatomy and transport capacity, and phloem loading of sugars to restore sieve tube turgor following the reduced plant water potential under drought conditions. However, δ(13)C and sugar composition of fine roots suggested that phloem transport of leaf sucrose to this belowground component was not impaired by mild drought and that sucrose was in a large part allocated towards fine roots in July, depending on tree social class. Hence, fine roots could represent a functional carbon sink during the dry seasonal periods, when transport and use of assimilates in other sink tissues are reduced. These results indicate a strict link between above- and belowground processes and highlight a rapid response of this Mediterranean forest to changes in environmental drivers to regulate source-sink relationships and carbon sink capacity. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Fine-Root Ecology Database (FRED): A Global Collection of Root Trait Data with Coincident Site, Vegetation, Edaphic, and Climatic Data, Version 2.

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

Iversen, C.M.; Powell, A.S.; McCormack, M.L.

The second version of the Fine-Root Ecology Database is available for download! Download the full FRED 2.0 data set, user guidance document, map, and list of data sources here. Prior to downloading the data, please read and follow the Data Use Guidelines, and it's worth checking out some tips for using FRED before you begin your analyses. Also, see here for an updating list of corrections to FRED 2.0.

Changes in carbon allocation to aboveground versus belowground forest components is driven by a trade-off involving mycorrhizal fungi, not fine roots

NASA Astrophysics Data System (ADS)

Ouimette, A.; Ollinger, S. V.; Hobbie, E. A.; Lepine, L. C.; Stephens, R.; Rowe, R.; Vadeboncoeur, M. A.; Tumber-Davila, S. J.

2017-12-01

Species composition and resource availability exert a strong influence on the dynamics of carbon allocation among different forest ecosystem components. Recent work in temperate forests has highlighted a tradeoff between carbon allocation to aboveground woody tissues (access to light), and belowground to fine roots (access to soil nutrients). Although root-associated mycorrhizal fungi are crucial for N acquisition and can receive 20% or more of annual net primary production, most studies fail to explicitly include carbon allocation to mycorrhizal fungi. In part, this is due to the inherent difficulties in accurately quantifying fungal production. We took several approaches to quantify production of mycorrhizal fungi, including a carbon budget approach and isotopic techniques. Here we present data on patterns of carbon allocation to aboveground (wood and foliar production), and belowground components (production of fine roots and mycorrhizal fungi), across temperate forest stands spanning a range of nitrogen availability and species composition. We found that as the proportion of conifer species decreased, and stand nitrogen availability increased, both the absolute amount and the fraction of net primary production increased for foliage, aboveground wood, and fine roots ("a rising tide lifts all boats"). While allocation to plant pools increased, allocation to mycorrhizal fungi significantly decreased with decreasing conifer dominance and increasing soil nitrogen availability. We did not find a strong trade-off between carbon allocation to fine roots and aboveground wood or foliage. Instead, a negative relationship is seen between allocation to mycorrhizal fungi and other plant pools. Effort to estimate carbon allocation to mycorrhizal fungi is important for gaining a more complete understanding of how ecosystems respond to changes in growth-limiting resources.

Spatial distribution of Eucalyptus roots in a deep sandy soil in the Congo: relationships with the ability of the stand to take up water and nutrients.

PubMed

Laclau, J P; Arnaud, M; Bouillet, J P; Ranger, J

2001-02-01

Spatial statistical analyses were performed to describe root distribution and changes in soil strength in a mature clonal plantation of Eucalyptus spp. in the Congo. The objective was to analyze spatial variability in root distribution. Relationships between root distribution, soil strength and the water and nutrient uptake by the stand were also investigated. We studied three, 2.35-m-wide, vertical soil profiles perpendicular to the planting row and at various distances from a representative tree. The soil profiles were divided into 25-cm2 grid cells and the number of roots in each of three diameter classes counted in each grid cell. Two profiles were 2-m deep and the third profile was 5-m deep. There was both vertical and horizontal anisotropy in the distribution of fine roots in the three profiles, with root density decreasing sharply with depth and increasing with distance from the stump. Roots were present in areas with high soil strength values (> 6,000 kPa). There was a close relationship between soil water content and soil strength in this sandy soil. Soil strength increased during the dry season mainly because of water uptake by fine roots. There were large areas with low root density, even in the topsoil. Below a depth of 3 m, fine roots were spatially concentrated and most of the soil volume was not explored by roots. This suggests the presence of drainage channels, resulting from the severe hydrophobicity of the upper soil.

Linking Belowground Plant Traits With Ecosystem Processes: A Multi-Biome Perspective

NASA Astrophysics Data System (ADS)

Iversen, C. M.; Norby, R. J.; Childs, J.; McCormack, M. L.; Walker, A. P.; Hanson, P. J.; Warren, J.; Sloan, V. L.; Sullivan, P. F.; Wullschleger, S.; Powell, A. S.

2015-12-01

Fine plant roots are short-lived, narrow-diameter roots that play an important role in ecosystem carbon, water, and nutrient cycling in biomes ranging from the tundra to the tropics. Root ecologists make measurements at a millimeter scale to answer a question with global implications: In response to a changing climate, how do fine roots modulate the exchange of carbon between soils and the atmosphere and how will this response affect our future climate? In a Free-Air CO2 Enrichment experiment in Oak Ridge, TN, elevated [CO2] caused fine roots to dive deeper into the soil profile in search of limiting nitrogen, which led to increased soil C storage in deep soils. In contrast, the fine roots of trees and shrubs in an ombrotrophic bog are constrained to nutrient-poor, oxic soils above the average summer water table depth, though this may change with warmer, drier conditions. Tundra plant species are similarly constrained to surface organic soils by permafrost or waterlogged soils, but have many adaptations that alter ecosystem C fluxes, including aerenchyma that oxygenate the rhizosphere but also allow direct methane flux to the atmosphere. FRED, a global root trait database, will allow terrestrial biosphere models to represent the complexity of root traits across the globe, informing both model representation of ecosystem C and nutrient fluxes, but also the gaps where measurements are needed on plant-soil interactions (for example, in the tropical biome). While the complexity of mm-scale measurements may never have a place in large-scale global models, close collaboration between empiricists and modelers can help to guide the scaling of important, yet small-scale, processes to quantify their important roles in larger-scale ecosystem fluxes.

Different Phylogenetic and Environmental Controls of First-order Root Morphological and Chemical Traits

NASA Astrophysics Data System (ADS)

Wang, R.; Wang, Q.; Zhao, N.; Yu, G.; He, N.

2017-12-01

Fine roots are the most distal roots that act as the primary belowground organs in acquiring limiting nutrients and water from the soil. However, limited by the inconsistency in definitions of fine roots and the different protocols among studies, knowledge of root system traits has, to date, still lagged far behind our understanding of above-ground traits. In particular, whether variation in fine root traits among the plant species along a single root economics spectrum and this underlying mechanism are still hotly debated. In this study, we sampled the first-order root using the standardized protocols, and measured six important root traits related to resource use strategies, from 181 plant species from subtropical to boreal forests. Base on this large dataset, we concluded that different phylogenetic and environmental factors affected on root thickness and nutrient, resulting in the decoupled pattern between them. Specifically, variation in species-level traits related to root thickness (including root diameter, RD and specific root length, SRL) was restricted by common ancestry and little plastic to the changing environments, whereas the large-scale variation in woody root nutrient was mainly controlled by environmental differences, especially soil variables. For community-level traits, mean annual temperature (MAT) mainly influenced the community-level root thickness through the direct effect of changes in plant species composition, while soil P had a positive influence effect on community-level root nitrogen concentration (CWM_RN), reflecting the strong influence of soil fertility on belowground root nutrient. The different environmental constraints and selective pressures acting between root thickness and nutrient traits allows for multiple ecological strategies to adapt to complex environmental conditions. In addition, strong relationships between community-level root traits and environmental variables, due to environmental filters, indicate that in contrast with individual species-level trait, community-aggregated root traits could be used to improve our ability to predict how the distribution of vegetation will change in response to a changing climate.

Fine root dynamics in a developing Populus deltoides plantation

Treesearch

Christel C. Kern; Jane M.-F. Johnson; Mark D. Coleman

2004-01-01

A closely spaced (1 x 1 m) cottonwood (Populus deltoides Bartr.) plantation was established to evaluate the effects of nutrient availability on fine root dynamics. Slow-release fertilizer (17:6:12 N,P,K plus micronutrients) was applied to 225-m2 plots at 0,50,10O and 200 kg N ha-1, and plots were...

Fine root dynamics in a developing Populus deltoides plantation

Treesearch

Christel C. Kern; Alexander L. Friend; Jane M. Johnson; Mark D. Coleman

2004-01-01

A closely spaced (1 x 1 m) cottonwood (Populus deltoides Bartr.) platation was established to evaluate the effects of nutrient availability on fine root dynamics. Slow-release fertilizer (17:6:12 N,P,K plus micronutrients) was applied to 225-m2 plots at 0, 50, 100, 200 kg N ha-1, and plots were monitored...

Characteristic of root decomposition in a tropical rainforest in Sarawak, Malaysi

NASA Astrophysics Data System (ADS)

Ohashi, Mizue; Makita, Naoki; Katayam, Ayumi; Kume, Tomonori; Matsumoto, Kazuho; Khoon Kho, L.

2016-04-01

Woody roots play a significant role in forest carbon cycling, as up to 60 percent of tree photosynthetic production can be allocated to belowground. Root decay is one of the main processes of soil C dynamics and potentially relates to soil C sequestration. However, much less attention has been paid for root litter decomposition compared to the studies of leaf litter because roots are hidden from view. Previous studies have revealed that physico-chemical quality of roots, climate, and soil organisms affect root decomposition significantly. However, patterns and mechanisms of root decomposition are still poorly understood because of the high variability of root properties, field environment and potential decomposers. For example, root size would be a factor controlling decomposition rates, but general understanding of the difference between coarse and fine root decompositions is still lacking. Also, it is known that root decomposition is performed by soil animals, fungi and bacteria, but their relative importance is poorly understood. In this study, therefore, we aimed to characterize the root decomposition in a tropical rainforest in Sarawak, Malaysia, and clarify the impact of soil living organisms and root sizes on root litter decomposition. We buried soil cores with fine and coarse root litter bags in soil in Lambir Hills National Park. Three different types of soil cores that are covered by 1.5 cm plastic mesh, root-impermeable sheet (50um) and fungi-impermeable sheet (1um) were prepared. The soil cores were buried in February 2013 and collected 4 times, 134 days, 226 days, 786 days and 1151 days after the installation. We found that nearly 80 percent of the coarse root litter was decomposed after two years, whereas only 60 percent of the fine root litter was decomposed. Our results also showed significantly different ratio of decomposition between different cores, suggesting the different contribution of soil living organisms to decomposition process.

Root production, distribution, and turnover in conventional and organic northern highbush blueberry systems

USDA-ARS?s Scientific Manuscript database

Northern highbush blueberry is a shallow-rooted crop with very fine, fibrous roots. Recently, we installed minirhizotrons (root observation tubes) in a conventional and an organic blueberry planting in western Oregon. We wanted to know exactly when and where new roots were being produced and determi...

Root production, distribution, and turnover in conventional and organic northern highbush blueberry systems

USDA-ARS?s Scientific Manuscript database

Northern highbush blueberry (Vaccinium corymbosum L.) is a shallow-rooted crop with very fine, fibrous roots. Recently, we installed minirhizotrons (root observation tubes) in a conventional and an organic blueberry planting in western Oregon. We wanted to know exactly when and where new roots were ...

[C, N and P stoichiometric characteristics of different root orders for three dominant tree species in subalpine forests of western Sichuan, China].

PubMed

Tang, Shi-shan; Yang, Wan-qin; Xiong, Li; Yin, Rui; Wang, Hai-peng; Zhang, Yan; Xu, Zhen-feng

2015-02-01

Fine root order was classified according to Pregitzer's method. This study measured carbon (C), nitrogen (N) and phosphorus (P) concentrations of the 1-5 root orders (diameter < 2 mm) in three dominant subalpine tree species (Betula albosinensis, Abies faxoniana and Picea asperata) of western Sichuan. Their stoichiometric ratios of different root orders were also calculated. The results showed that C concentration, C/N and C/P increased, but N and P concentrations decreased from the first to fifth order of fine root for all tree species. No significant changes in N/P among root orders were detected in each species. There were significant differences in C, N, P concentrations and their stoichiometric ratios among the tree species. The species-associated differences were dependent on root order. There were significant correlations between C, N, P concentrations and their stoichiometric ratios in the three tree species.

Growth enhancement of Quercus alba saplings by CO[sub 2] enrichment under field conditions

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

Norby, R.J.; O'Neill, E.G.; Wullschleger, S.D.

1993-06-01

White oak (Quercus alba L.) trees were grown in soil under field conditions for four growing seasons in open-top chambers containing ambient air continuously enriched with 0, 150, or 300 [mu]mol/mol CO[sub 2]. The trees were significantly larger in elevated CO[sub 2]: whole-tree mass (including woody roots) was 36% greater in +150 and 140% greater in +300 compared to ambient-grown trees. There were no significant effects of CO[sub 2] concentration on root-to-shoot or leaf area ratios. The stimulatory effect of CO[sub 2] occurred during seedling establishment, and there was no effect of CO[sub 2] on relative growth rate after themore » first field season. However, photosynthesis remained consistently higher in elevated CO[sub 2], foliar respiration was reduced, and fine root density and CO[sub 2] efflux from the soil were higher, as previously reported with yellow- poplar trees.« less

Stress differentially impacts reserve pools and root exudation: implications for ecosystem functioning and carbon balance

NASA Astrophysics Data System (ADS)

Landhäusser, Simon; Karst, Justine; Wiley, Erin; Gaster, Jacob

2016-04-01

Environmental stress can influence carbon assimilation and the accumulation and distribution of carbon between growth, reserves, and exudation; however, it is unclear how these processes vary by different stress types. Partitioning of carbon to growth and reserves in plants might also vary between different organs. Roots reserves are of particular interest as they link the plant with the soil carbon cycle through exudation. Simple models of diffusion across concentration gradients predict the more C reserves in roots, the more C should be exuded from roots. However, the mechanisms underlying the accumulation and loss of C from roots may differ depending on the stress experienced by the plants. In a controlled study we tested whether different types of stresses (shade, cold soil, and drought) have differential effects on the distribution, abundance, and form (sugar vs. starch) of carbohydrates in seedlings, and whether these changes alone could explain differences in root exudation between stress types. Non-structural carbohydrate (NSC) concentration and pool sizes varied by stress type and between organs. Mass-specific C exudation increased with fine root sugar concentration; however, stress type affected exudation independently of reserve concentration. Seedlings exposed to cold soils exuded the most C on a per root mass basis followed by shade and drought. Through 13C labeling, we also found that depending on the stress type, aspen seedlings may be less able to control the loss of C to the soil compared with unstressed seedlings, resulting in more C leaked to the rhizosphere. The loss of C beyond that predicted by simple concentration gradients might have important implications for ecosystem functioning and carbon balance. If stressed plants lose proportionally more carbon to the soil, existing interactions between plants and soils may decouple under stress, and may include unexpected C fluxes between trees, soils and the atmosphere with a changing climate.

[Effects of broadleaf plantation and Chinese fir (Cunninghamia lanceolata) plantation on soil carbon and nitrogen pools].

PubMed

Wan, Xiao-Hua; Huang, Zhi-Qun; He, Zong-Ming; Hu, Zhen-Hong; Yang, Jing-Yu; Yu, Zai-Peng; Wang, Min-huang

2013-02-01

A comparative study was conducted on the soil C and N pools in a 19-year-old broadleaf plantation and a Chinese fir (Cunninghamia lanceolata) plantation in subtropical China, aimed to understand the effects of tree species on the soil C and N pools. In the broadleaf plantation, the C and N stocks in 0-40 cm soil layer were 99.41 Mg.hm-2 and 6. 18 Mg.hm-2, being 33.1 % and 22. 6 % larger than those in Chinese fir plantation, respectively. The standing biomass and the C and N stocks of forest floor in the broadleaf plantation were 1.60, 1.49, and 1.52 times of those in Chinese fir plantation, respectively, and the differences were statistically significant. There was a significant negative relationship between the forest floor C/N ratio and the soil C and N stocks. In the broadleaf plantation, the fine root biomass in 0-80 cm soil layer was 1.28 times of that in the Chinese fir plantation, and the fine root biomass in 0-10 cm soil layer accounted for 48. 2 % of the total fine root biomass. The C and N stocks in the fine roots in the broadleaf plantation were also higher than those in the Chinese fir plantation. In 0-10 cm soil layer, its C stock had a significant positive relationship with the fine root C stock. It was suggested that as compared with Chinese fir plantation, the soil in broadleaf plantation had a greater potential to accumulate organic carbon.

EFFECTS OF ELEVATED CO2 AND N-FERTILIZATION ON SURVIVAL OF PONDEROSA PINE FINE ROOTS

EPA Science Inventory

We used minihizaotrons to assess the effects of elevated CO2N and season on the life-span of ponderosa pine (Pinus ponderosa Dougl. Ex Laws.) fine roots. CO2 levels were ambient air (A), ambient air + 175 ?mol mol-1 (A+175) and ambient air + 350 ?mol mol-1 (A+350). N treatments ...

EFFECTS OF ELEVATED CO-2 AND N FERTILIZATION ON FINE ROOT DYNAMICS AND FUNGAL GROWTH IN SEEDLING PINUS PONDEROSA

EPA Science Inventory

The effects of elevated CO-2 and N fertilization on fine root growth of Pinus ponderosa Dougl. ex P. Laws. C. Laws., grown in native soil in open-top field-exposure chambers at Placerville, CA, were monitored for a 2-year period using minirhizotrons. The experimental design was a...

Temperature sensitivity of microbial respiration of fine root litter in a temperate broad-leaved forest.

PubMed

Makita, Naoki; Kawamura, Ayumi

2015-01-01

The microbial decomposition respiration of plant litter generates a major CO2 efflux from terrestrial ecosystems that plays a critical role in the regulation of carbon cycling on regional and global scales. However, the respiration from root litter decomposition and its sensitivity to temperature changes are unclear in current models of carbon turnover in forest soils. Thus, we examined seasonal changes in the temperature sensitivity and decomposition rates of fine root litter of two diameter classes (0-0.5 and 0.5-2.0 mm) of Quercus serrata and Ilex pedunculosa in a deciduous broad-leaved forest. During the study period, fine root litter of both diameter classes and species decreased approximately exponentially over time. The Q10 values of microbial respiration rates of root litter for the two classes were 1.59-3.31 and 1.28-6.27 for Q. serrata and 1.36-6.31 and 1.65-5.86 for I. pedunculosa. A significant difference in Q10 was observed between the diameter classes, indicating that root diameter represents the initial substrate quality, which may determine the magnitude of Q10 value of microbial respiration. Changes in these Q10 values were related to seasonal soil temperature patterns; the values were higher in winter than in summer. Moreover, seasonal variations in Q10 were larger during the 2-year decomposition period than the 1-year period. These results showed that the Q10 values of fine root litter of 0-0.5 and 0.5-2.0 mm have been shown to increase with lower temperatures and with the higher recalcitrance pool of the decomposed substrate during 2 years of decomposition. Thus, the temperature sensitivity of microbial respiration in root litter showed distinct patterns according to the decay period and season because of the temperature acclimation and adaptation of the microbial decomposer communities in root litter.

Exploitation of nutrient- and C-rich paleosols by deep rooting plants in Dutch drift- and coversands

NASA Astrophysics Data System (ADS)

Gocke, Martina; Kessler, Fabian; van Mourik, Jan; Jansen, Boris; Wiesenberg, Guido L. B.

2015-04-01

Plant roots are commonly assumed to be most abundant in topsoil, with strongly decreasing frequencies in underlying soil horizons with incrasing depth and almost absence of roots below the uppermost few dm due to unfavorable environmental conditions in terms of e.g. aeration, nutrient availability or water, that hamper root growth. It still remains unknown, to which extent roots might be able to exploit deeper parts of soils and underlying soil parent material as well as burried paleosols. The study site is located in SE Netherlands. Undisturbed oak forests developed about 200 years ago on stabilized driftsand, deposited on a plaggic Anthrosol after approximately 700 years of agricultural use. The soil profile, consisting of the recent initial Podzol in driftsand, overlying 1.1 m thick plaggic deposits that were established in a 0.5 m thick residual Podzol in coversand, was excavated in a pit of 2.3 m depth. Living and dead roots were counted throughout the profile on both, the vertical wall and horizontal levels. Additionally, soil or sediment samples free of visible root remains were collected in depth intervals between 0.05 m and 0.15 m from topsoil down to the coversand. A multi-proxy approach, including assessment of bulk elemental composition of soil, sediments and paleosol and molecular structure of organic matter therein, organic carbon contents, bulk density and pH was applied in order to comprehensively describe the varying environmental conditions within the soil profile and in transects from roots to root-free material. The burried agricultural soil revealed low density and high organic carbon contents compared to the coversand parent material, and especially in its lower part, high phosphorous contents. In contrast, the burried Podzol was characterized by completely different geochemical and physical properties, like increasing pH with depth and high iron and aluminium contents. In the recent initial Podzol, fine roots (≤ 2 mm), deriving from both oak trees and understory vegetation, immediately decreased from 476 m-2 to 24 m-2, whereas medium roots (2-5 mm) from oak trees continuously increased from 8 m-2 at the surface to 188 m-2 within the upper part of the agricultural soil. Both, frequencies of fine and medium roots peaked at 4.448 m-2 and 216 m-2, respectively, in the uppermost part of the burried Podzol, thus considerably exceeding topsoil abundances. Comparison of these results with those obtained at the profile wall demonstrated that fine root abundances might be considerably underestimated by the more traditional approach of profile wall investigation, because fine roots were growing vertically to exploit the nutrient-rich burried paleosols. Unlike fine roots, medium roots and even more, large roots (> 5 mm) were not able to penetrate the hard sesquioxide crusts of the burried Podzol in larger numbers. Our results show that roots are able to deeply penetrate the soil and underlying soil parent material or paleosols, if the latter provides nutrition benefits. Root distribution strongly depends on physical and chemical properties of the deep subsoil, which should be taken into account when interpreting complex soil profiles covering recent and paleosols.

Influences of canopy photosynthesis and summer rain pulses on root dynamics and soil respiration in a young ponderosa pine forest.

PubMed

Misson, Laurent; Gershenson, Alexander; Tang, Jianwu; McKay, Megan; Cheng, Weixin; Goldstein, Allen

2006-07-01

Our first objective was to link the seasonality of fine root dynamics with soil respiration in a ponderosa pine (Pinus ponderosa P. & C. Lawson) plantation located in the Sierra Nevada of California. The second objective was to examine how canopy photosynthesis influences fine root initiation, growth and mortality in this ecosystem. We compared CO2 flux measurements with aboveground and belowground root dynamics. Initiation of fine root growth coincided with tree stem thickening and shoot elongation, preceding new needle growth. In the spring, root, shoot and stem growth occurred simultaneously with the increase in canopy photosynthesis. Compared with the other tree components, initial growth rate of fine roots was the highest and their growing period was the shortest. Both above and belowground components completed 90% of their growth by the end of July and the growing season lasted approximately 80 days. The period for optimal growth is short at the study site because of low soil temperatures during winter and low soil water content during summer. High photosynthetic rates were observed following unusual late-summer rains, but tree growth did not resume. The autotrophic contribution to soil respiration was 49% over the whole season, with daily contributions ranging between 18 and 87%. Increases in soil and ecosystem respiration were observed during spring growth; however, the largest variation in soil respiration occurred during summer rain events when no growth was observed. Both the magnitude and persistence of the soil respiration pulses were positively correlated with the amount of rain. These pulses accounted for 16.5% of soil respiration between Days 130 and 329.

Root colonization and spore abundance of arbuscular mycorrhizal fungi in distinct successional stages from an Atlantic rainforest biome in southern Brazil.

PubMed

Zangaro, Waldemar; Rostirola, Leila Vergal; de Souza, Priscila Bochi; de Almeida Alves, Ricardo; Lescano, Luiz Eduardo Azevedo Marques; Rondina, Artur Berbel Lírio; Nogueira, Marco Antonio; Carrenho, Rosilaine

2013-04-01

The influence of plant functional groups and moderate seasonality on arbuscular mycorrhizal (AM) fungal status (root colonization and spore density) was investigated during 13 consecutive months in a chronosequence of succession in southern Brazil, consisting of grassland field, scrub vegetation, secondary forest and mature forest, in a region of transition from tropical to subtropical zones. AM root colonization and spore density decreased with advancing succession and were highest in early successional sites with grassland and scrub vegetation, intermediary in the secondary forest and lowest in the mature forest. They were little influenced by soil properties, but were sufficiently influenced by the fine root nutrient status and fine root traits among different functional plant groups. AM root colonization and spore density were higher during the favourable plant growth season (spring and summer) than during the less favourable plant growth season (autumn and winter). Spore density displayed significant seasonal variation at all sites, whilst root colonization displayed significant seasonal variation in grassland, scrub and secondary forest, but not in mature forest. The data suggest that (1) different plant functional groups display different relationships with AM fungi, influencing their abundance differentially; (2) plant species from early successional phases are more susceptible to AM root colonization and maintain higher AM sporulation than late successional species; (3) fine root traits and nutrient status influence these AM fungal attributes; and (4) higher AM spore production and root colonization is associated with the season of higher light incidence and temperature, abundant water in soil and higher plant metabolic activity.

Foraging strategies in trees of different root morphology: the role of root lifespan.

PubMed

Adams, Thomas S; McCormack, M Luke; Eissenstat, David M

2013-09-01

Resource exploitation of patches is influenced not simply by the rate of root production in the patches but also by the lifespan of the roots inhabiting the patches. We examined the effect of sustained localized nitrogen (N) fertilization on root lifespan in four tree species that varied widely in root morphology and presumed foraging strategy. The study was conducted in a 12-year-old common garden in central Pennsylvania using a combination of data from minirhizotron and root in-growth cores. The two fine-root tree species, Acer negundo L. and Populus tremuloides Michx., exhibited significant increases in root lifespan with local N fertilization; no significant responses were observed in the two coarse-root tree species, Sassafras albidum Nutt. and Liriodendron tulipifera L. Across species, coarse-root tree species had longer median root lifespan than fine-root tree species. Localized N fertilization did not significantly increase the N concentration or the respiration of the roots growing in the N-rich patch. Our results suggest that some plant species appear to regulate the lifespan of different portions of their root system to improve resource acquisition while other species do not. Our results are discussed in the context of different strategies of foraging of nutrient patches in species of different root morphology.

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

PubMed

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

2017-05-01

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

The Role of Fine Root Dynamics in the N and P Cycles of Regenerating Upland Oak-Hickory Forests

Treesearch

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

1998-01-01

ln naturally regenerating hardwood forest stands, inputs of organic matter and nutrients from fine root turnover and decomposition are significant but not well-quantified. Four forest stands in southern Indiana-aged 6, 12, 31, and approximately 100 years since clearcutting at the time of the study-were chosen to represent the different developmental stages of upland...

CO2 AND N-FERTILIZATION EFFECTS ON FINE ROOT LENGTH, PRODUCTION, AND MORTALITY: A 4-YEAR PONDEROSA PINE STUDY

EPA Science Inventory

We conducted a 4-year study of Pinus ponderosa fine root (<2 mm) responses to atmospheric CO2 and N-fertilization. Seedlings were grown in open-top chambers at 3 CO2 levels (ambient, ambient+175 mol/mol, ambient+350 mol/mol) and 3 N-fertilization levels (0, 10, 20 g?m-2?yr-1). ...

Traceable Calibration, Performance Metrics, and Uncertainty Estimates of Minirhizotron Digital Imagery for Fine-Root Measurements

PubMed Central

Roberti, Joshua A.; SanClements, Michael D.; Loescher, Henry W.; Ayres, Edward

2014-01-01

Even though fine-root turnover is a highly studied topic, it is often poorly understood as a result of uncertainties inherent in its sampling, e.g., quantifying spatial and temporal variability. While many methods exist to quantify fine-root turnover, use of minirhizotrons has increased over the last two decades, making sensor errors another source of uncertainty. Currently, no standardized methodology exists to test and compare minirhizotron camera capability, imagery, and performance. This paper presents a reproducible, laboratory-based method by which minirhizotron cameras can be tested and validated in a traceable manner. The performance of camera characteristics was identified and test criteria were developed: we quantified the precision of camera location for successive images, estimated the trueness and precision of each camera's ability to quantify root diameter and root color, and also assessed the influence of heat dissipation introduced by the minirhizotron cameras and electrical components. We report detailed and defensible metrology analyses that examine the performance of two commercially available minirhizotron cameras. These cameras performed differently with regard to the various test criteria and uncertainty analyses. We recommend a defensible metrology approach to quantify the performance of minirhizotron camera characteristics and determine sensor-related measurement uncertainties prior to field use. This approach is also extensible to other digital imagery technologies. In turn, these approaches facilitate a greater understanding of measurement uncertainties (signal-to-noise ratio) inherent in the camera performance and allow such uncertainties to be quantified and mitigated so that estimates of fine-root turnover can be more confidently quantified. PMID:25391023

Identification of coniferous fine roots to species using ribosomal PCR products of pooled root samples

EPA Science Inventory

Background/Question/Methods To inform an individual-based forest stand model emphasizing belowground competition, we explored the potential of using the relative abundances of ribosomal PCR products from pooled and milled roots, to allocate total root biomass to each of the thre...

Chemistry and long-term decomposition of roots of Douglas-fir grown under elevated atmospheric carbon dioxide and warming conditions.

PubMed

Chen, H; Rygiewicz, P T; Johnson, M G; Harmon, M E; Tian, H; Tang, J W

2008-01-01

Elevated atmospheric CO(2) concentrations and warming may affect the quality of litters of forest plants and their subsequent decomposition in ecosystems, thereby potentially affecting the global carbon cycle. However, few data on root tissues are available to test this feedback to the atmosphere. In this study, we used fine (diameter < or = 2 mm) and small (2-10 mm) roots of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings that were grown for 4 yr in a 2 x 2 factorial experiment: ambient or elevated (+ 180 ppm) atmospheric CO(2) concentrations, and ambient or elevated (+3.8 degrees C) atmospheric temperature. Exposure to elevated CO(2) significantly increased water-soluble extractives concentration (%WSE), but had little effect on the concentration of N, cellulose, and lignin of roots. Elevated temperature had no effect on substrate quality except for increasing %WSE and decreasing the %lignin content of fine roots. No significant interaction was found between CO(2) and temperature treatments on substrate quality, except for %WSE of the fine roots. Short-term (< or = 9 mo) root decomposition in the field indicated that the roots from the ambient CO(2) and ambient temperature treatment had the slowest rate. However, over a longer period of incubation (9-36 mo) the influence of initial substrate quality on root decomposition diminished. Instead, the location of the field incubation sites exhibited significant control on decomposition. Roots at the warmer, low elevation site decomposed significantly faster than the ones at the cooler, high elevation site. This study indicates that short-term decomposition and long-term responses are not similar. It also suggests that increasing atmospheric CO(2) had little effect on the carbon storage of Douglas-fir old-growth forests of the Pacific Northwest.

Fine Root Dynamics and Forest Production Across a Calcium Gradient in Northern Hardwood and Conifer Ecosystems

Treesearch

Byung Bae Park; Ruth D. Yanai; Timothy J. Fahey; Scott W. Bailey; Thomas G. Siccama; James B. Shanley; Natalie L. Cleavitt

2008-01-01

Losses of soil base cations due to acid rain have been implicated in declines of red spruce and sugar maple in the northeastern USA. We studied fine root and aboveground biomass and production in five northern hardwood and three conifer stands differing in soil Ca status at Sleepers River, VT; Hubbard Brook, NH; and Cone Pond, NH. Neither aboveground biomass and...

Short-term effects of seasonal prescribed burning on the ectomycorrhizal fungal community and fine root biomass in ponderosa pine stands in the Blue Mountains of Oregon.

Treesearch

J.E. Smith; D. McKay; C.G. Niwa; W.G. Thies; G. Brenner; J.W. Spatafora

2004-01-01

The effects of seasonal prescribed fire on the belowground ectomycorrhizal community and live fine root biomass were investigated before, 1 year after, and 2 years after prescribed underburning. Ectomycorrhizas were sampled from four replications of three treatments (fall underburning, spring underburning, and a nonburned.control) in a randomized complete block design...

Comparing Soil Organic Carbon Dynamics in Perennial Grasses and Shrubs in a Saline-Alkaline Arid Region, Northwestern China

PubMed Central

Su, Jiaqi; Zhang, Jingli; Zheng, Yuanrun; Ni, Jian; Xiao, Chunwang; Wang, Renzhong

2012-01-01

Background Although semi-arid and arid regions account for about 40% of terrestrial surface of the Earth and contain approximately 10% of the global soil organic carbon stock, our understanding of soil organic carbon dynamics in these regions is limited. Methodology/Principal Findings A field experiment was conducted to compare soil organic carbon dynamics between a perennial grass community dominated by Cleistogenes squarrosa and an adjacent shrub community co-dominated by Reaumuria soongorica and Haloxylon ammodendron, two typical plant life forms in arid ecosystems of saline-alkaline arid regions in northwestern China during the growing season 2010. We found that both fine root biomass and necromass in two life forms varied greatly during the growing season. Annual fine root production in the perennial grasses was 45.6% significantly higher than in the shrubs, and fine root turnover rates were 2.52 and 2.17 yr−1 for the perennial grasses and the shrubs, respectively. Floor mass was significantly higher in the perennial grasses than in the shrubs due to the decomposition rate of leaf litter in the perennial grasses was 61.8% lower than in the shrubs even though no significance was detected in litterfall production. Soil microbial biomass and activity demonstrated a strong seasonal variation with larger values in May and September and minimum values in the dry month of July. Observed higher soil organic carbon stocks in the perennial grasses (1.32 Kg C m−2) than in the shrubs (1.12 Kg C m−2) might be attributed to both greater inputs of poor quality litter that is relatively resistant to decay and the lower ability of microorganism to decompose these organic matter. Conclusions/Significance Our results suggest that the perennial grasses might accumulate more soil organic carbon with time than the shrubs because of larger amounts of inputs from litter and slower return of carbon through decomposition. PMID:22900067

Comparing soil organic carbon dynamics in perennial grasses and shrubs in a saline-alkaline arid region, northwestern China.

PubMed

Zhou, Yong; Pei, Zhiqin; Su, Jiaqi; Zhang, Jingli; Zheng, Yuanrun; Ni, Jian; Xiao, Chunwang; Wang, Renzhong

2012-01-01

Although semi-arid and arid regions account for about 40% of terrestrial surface of the Earth and contain approximately 10% of the global soil organic carbon stock, our understanding of soil organic carbon dynamics in these regions is limited. A field experiment was conducted to compare soil organic carbon dynamics between a perennial grass community dominated by Cleistogenes squarrosa and an adjacent shrub community co-dominated by Reaumuria soongorica and Haloxylon ammodendron, two typical plant life forms in arid ecosystems of saline-alkaline arid regions in northwestern China during the growing season 2010. We found that both fine root biomass and necromass in two life forms varied greatly during the growing season. Annual fine root production in the perennial grasses was 45.6% significantly higher than in the shrubs, and fine root turnover rates were 2.52 and 2.17 yr(-1) for the perennial grasses and the shrubs, respectively. Floor mass was significantly higher in the perennial grasses than in the shrubs due to the decomposition rate of leaf litter in the perennial grasses was 61.8% lower than in the shrubs even though no significance was detected in litterfall production. Soil microbial biomass and activity demonstrated a strong seasonal variation with larger values in May and September and minimum values in the dry month of July. Observed higher soil organic carbon stocks in the perennial grasses (1.32 Kg C m(-2)) than in the shrubs (1.12 Kg C m(-2)) might be attributed to both greater inputs of poor quality litter that is relatively resistant to decay and the lower ability of microorganism to decompose these organic matter. Our results suggest that the perennial grasses might accumulate more soil organic carbon with time than the shrubs because of larger amounts of inputs from litter and slower return of carbon through decomposition.

Root development during soil genesis: effects of root-root interactions, mycorrhizae, and substrate

NASA Astrophysics Data System (ADS)

Salinas, A.; Zaharescu, D. G.

2015-12-01

A major driver of soil formation is the colonization and transformation of rock by plants and associated microbiota. In turn, substrate chemical composition can also influence the capacity for plant colonization and development. In order to better define these relationships, a mesocosm study was set up to analyze the effect mycorrhizal fungi, plant density and rock have on root development, and to determine the effect of root morphology on weathering and soil formation. We hypothesized that plant-plant and plant-fungi interactions have a stronger influence on root architecture and rock weathering than the substrate composition alone. Buffalo grass (Bouteloua dactyloides) was grown in a controlled environment in columns filled with either granular granite, schist, rhyolite or basalt. Each substrate was given two different treatments, including grass-microbes and grass-microbes-mycorrhizae and incubated for 120, 240, and 480 days. Columns were then extracted and analyzed for root morphology, fine fraction, and pore water major element content. Preliminary results showed that plants produced more biomass in rhyolite, followed by schist, basalt, and granite, indicating that substrate composition is an important driver of root development. In support of our hypothesis, mycorrhizae was a strong driver of root development by stimulating length growth, biomass production, and branching. However, average root length and branching also appeared to decrease in response to high plant density, though this trend was only present among roots with mycorrhizal fungi. Interestingly, fine fraction production was negatively correlated with average root thickness and volume. There is also slight evidence indicating that fine fraction production is more related to substrate composition than root morphology, though this data needs to be further analyzed. Our hope is that the results of this study can one day be applied to agricultural research in order to promote the production of crops on traditionally un-arable land.

Comparison of alternative image reformatting techniques in micro-computed tomography and tooth clearing for detailed canal morphology.

PubMed

Lee, Ki-Wook; Kim, Yeun; Perinpanayagam, Hiran; Lee, Jong-Ki; Yoo, Yeon-Jee; Lim, Sang-Min; Chang, Seok Woo; Ha, Byung-Hyun; Zhu, Qiang; Kum, Kee-Yeon

2014-03-01

Micro-computed tomography (MCT) shows detailed root canal morphology that is not seen with traditional tooth clearing. However, alternative image reformatting techniques in MCT involving 2-dimensional (2D) minimum intensity projection (MinIP) and 3-dimensional (3D) volume-rendering reconstruction have not been directly compared with clearing. The aim was to compare alternative image reformatting techniques in MCT with tooth clearing on the mesiobuccal (MB) root of maxillary first molars. Eighteen maxillary first molar MB roots were scanned, and 2D MinIP and 3D volume-rendered images were reconstructed. Subsequently, the same MB roots were processed by traditional tooth clearing. Images from 2D, 3D, 2D + 3D, and clearing techniques were assessed by 4 endodontists to classify canal configuration and to identify fine anatomic structures such as accessory canals, intercanal communications, and loops. All image reformatting techniques in MCT showed detailed configurations and numerous fine structures, such that none were classified as simple type I or II canals; several were classified as types III and IV according to Weine classification or types IV, V, and VI according to Vertucci; and most were nonclassifiable because of their complexity. The clearing images showed less detail, few fine structures, and numerous type I canals. Classification of canal configuration was in 100% intraobserver agreement for all 18 roots visualized by any of the image reformatting techniques in MCT but for only 4 roots (22.2%) classified according to Weine and 6 (33.3%) classified according to Vertucci, when using the clearing technique. The combination of 2D MinIP and 3D volume-rendered images showed the most detailed canal morphology and fine anatomic structures. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Localization of ginsenosides in Panax ginseng with different age by matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry imaging.

PubMed

Bai, Hangrui; Wang, Shujuan; Liu, Jianjun; Gao, Dan; Jiang, Yuyang; Liu, Hongxia; Cai, Zongwei

2016-07-15

The root of Panax ginseng C.A. Mey. (P. ginseng) is one of the most popular traditional Chinese medicines, with ginsenosides as its main bioactive components. Because different ginsenosides have varied pharmacological effects, extraction and separation of ginsenosides are usually required for the investigation of pharmacological effects of different ginsenosides. However, the contents of ginsenosides vary with the ages and tissues of P. ginseng root. In this research, an efficient method to explore the distribution of ginsenosides and differentiate P. ginseng roots with different ages was developed based on matrix assisted laser desorption/ionization time-of-flight mass spectrometry imaging (MALDI-TOF-MSI). After a simple sample preparation, there were 18 peaks corresponding to 31 ginsenosides with distinct localization in the mass range of m/z 700-1400 identified by MALDI-TOF-MSI and MALDI-TOF-MS/MS. All the three types of ginsenosides were successfully detected and visualized in images, which could be correlated with anatomical features. The P. ginseng at the ages of 2, 4 and 6 could be differentiated finely through the principal component analysis of data collected from the cork based on the ion images but not data from the whole tissue. The experimental result implies that the established method for the direct analysis of metabolites in plant tissues has high potential for the rapid identification of metabolites and analysis of their localizations in medicinal herbs. Furthermore, this technique also provides valuable information for the component-specific extraction and pharmacological research of herbs. Copyright © 2015 Elsevier B.V. All rights reserved.

Seasonal changes in morphophysiological traits of two native Patagonian shrubs from Argentina with different drought resistance strategies.

PubMed

Varela, M Celeste; Reinoso, Herminda; Luna, Virginia; Cenzano, Ana M

2018-06-01

In semi-arid regions, plants develop various biochemical and physiological strategies to adapt to dry periods. Understanding the resistance mechanisms to dry periods under field conditions is an important topic in ecology. Larrea divaricata and Lycium chilense provide various ecological services. The aim of this work is to elucidate new morpho-histological, biochemical and hormonal traits that contribute to the drought resistance strategies of two native shrubs. Green leaves and fine roots from L. divaricata and L. chilense were collected in each season for one year, and various traits were measured. The hormone (abscisic acid, ABA-glucose ester, gibberellins A 1 and A 3 , and indole acetic acid) contents were determined by liquid chromatography coupled to mass spectrometry. Rainfall data and the soil water content were also measured. A multivariate analysis showed that green leaves from L. divaricata showed high values for the leaf dry weight, blade leaf thickness and ABA content in the summer compared with those from L. chilense. Fine roots from L. divaricata had high RWC and high IAA levels during the autumn-dry period compared with those from L. chilense, but both had similar levels during the winter and spring. Our results support the notion that species with different drought resistance mechanisms (avoidance or tolerance) display different responses to dry periods throughout the year. Larrea divaricata, which exhibits more xerophytic traits, modified its morphology and maintained its physiological parameters (high RWC in leaves and roots, high ABA levels in leaves during summer, high GA 3 in leaves and high IAA in roots during autumn) to tolerate dry periods, whereas Lycium chilense, which displays more mesophytic traits, uses strategies to avoid dry periods (loss of leaves during autumn and winter, high RWC in leaves, high ABA-GE and GA 3 in leaves during summer, high GA 1 and GA 3 in roots during summer, and high IAA in roots during autumn and summer) and thus has a metabolism that is more dependent on water availability for growth. Copyright © 2018. Published by Elsevier Masson SAS.

Carbon and nitrogen distribution in oak-hickory forests distributed along a productivity gradient

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

Reber, R.T.; Kaczmarek, D.J.; Pope, P.E.

1993-12-31

Biomass, carbon and nitrogen pools were determined for oak-hickory forests of varying productivity. Little information of this type is available for the central hardwood region. Six oak-hickory dominated forests were chosen to represent a range in potential site productivity as influenced by soil type, amount of recyclable nutrients and available water. Biomass, carbon and nitrogen storage were determined for the following components: above ground standing biomass, fine root biomass, forest floor organic layers and litterfall. As site sequestered at each site was dependent more on the amount of living biomass at each site Litterfall, to some extent, increased with increasingmore » site productivity. As potential site productivity decreased, total fine root biomass increased. The data suggest that as site quality decreased fine root production and turnover may become as important in nutrient cycling as annual litterfall.« less

Effect of tree roots on a shear zone: modeling reinforced shear stress.

Treesearch

Kazutoki Abe; Robert R. Ziemer

1991-01-01

Tree roots provide important soil reinforcement that impoves the stability of hillslopes. After trees are cut and roots begin to decay, the frequency of slope failures can increase. To more fully understand the mechanics of how tree roots reinforce soil, fine sandy soil containing pine roots was placed in a large shear box in horizontal layers and sheared across a...

Bush Sophora Root polysaccharide and its sulfate can scavenge free radicals resulted from duck virus hepatitis.

PubMed

Chen, Yun; Xiong, Wen; Zeng, Ling; Wang, Yu; Zhang, Shuaibing; Xu, Meiyun; Song, Meiyun; Wang, Yixuan; Du, Hongxu; Liu, Jiaguo; Wang, Deyun; Wu, Yi; Hu, Yuanliang

2014-05-01

In order to study the antioxidant effect of Bush Sophora Root polysaccharide (BSRPS) and its sulfate on anti-duck virus hepatitis (DVH), sulfated Bush Sophora Root polysaccharide (sBSRPS) was prepared by chlorosulfonic acid-pyridine method. Ducklings were fed with BSRPS and sBSRPS after challenged DHAV. Death was monitored, evaluation indexes of peroxidative and hepatic injury at the initial (4th and 8th hour) and later (54th hour) stages were detected. The results showed a fine treatment effect of BSRPS and sBSRPS. Visual hepatic pathological injury severities were less serious after the treatment. At the initial stage, free radical levels in all groups were the same, and BSRPS and sBSRPS reduced the hepatic injury through inhibiting virus replication. At the later stage, mass free radicals were detected in VC group while free radical levels in BSRPS and sBSRPS groups were significantly lower than VC group. The antioxidant effect of BSRPS and sBSRPS might alleviate the hepatic injury. Copyright © 2014 Elsevier B.V. All rights reserved.

Sources and geographical origins of fine aerosols in Paris (France)

NASA Astrophysics Data System (ADS)

Bressi, M.; Sciare, J.; Ghersi, V.; Mihalopoulos, N.; Petit, J.-E.; Nicolas, J. B.; Moukhtar, S.; Rosso, A.; Féron, A.; Bonnaire, N.; Poulakis, E.; Theodosi, C.

2013-12-01

The present study aims at identifying and apportioning the major sources of fine aerosols in Paris (France) - the second largest megacity in Europe -, and determining their geographical origins. It is based on the daily chemical composition of PM2.5 characterised during one year at an urban background site of Paris (Bressi et al., 2013). Positive Matrix Factorization (EPA PMF3.0) was used to identify and apportion the sources of fine aerosols; bootstrapping was performed to determine the adequate number of PMF factors, and statistics (root mean square error, coefficient of determination, etc.) were examined to better model PM2.5 mass and chemical components. Potential Source Contribution Function (PSCF) and Conditional Probability Function (CPF) allowed the geographical origins of the sources to be assessed; special attention was paid to implement suitable weighting functions. Seven factors named ammonium sulfate (A.S.) rich factor, ammonium nitrate (A.N.) rich factor, heavy oil combustion, road traffic, biomass burning, marine aerosols and metals industry were identified; a detailed discussion of their chemical characteristics is reported. They respectively contribute 27, 24, 17, 14, 12, 6 and 1% of PM2.5 mass (14.7 μg m-3) on the annual average; their seasonal variability is discussed. The A.S. and A.N. rich factors have undergone north-eastward mid- or long-range transport from Continental Europe, heavy oil combustion mainly stems from northern France and the English Channel, whereas road traffic and biomass burning are primarily locally emitted. Therefore, on average more than half of PM2.5 mass measured in the city of Paris is due to mid- or long-range transport of secondary aerosols stemming from continental Europe, whereas local sources only contribute a quarter of the annual averaged mass. These results imply that fine aerosols abatement policies conducted at the local scale may not be sufficient to notably reduce PM2.5 levels at urban background sites in Paris, suggesting instead more coordinated strategies amongst neighbouring countries. Similar conclusions might be drawn in other continental urban background sites given the transboundary nature of PM2.5 pollution.

Sources and geographical origins of fine aerosols in Paris (France)

NASA Astrophysics Data System (ADS)

Bressi, M.; Sciare, J.; Ghersi, V.; Mihalopoulos, N.; Petit, J.-E.; Nicolas, J. B.; Moukhtar, S.; Rosso, A.; Féron, A.; Bonnaire, N.; Poulakis, E.; Theodosi, C.

2014-08-01

The present study aims at identifying and apportioning fine aerosols to their major sources in Paris (France) - the second most populated "larger urban zone" in Europe - and determining their geographical origins. It is based on the daily chemical composition of PM2.5 examined over 1 year at an urban background site of Paris (Bressi et al., 2013). Positive matrix factorization (EPA PMF3.0) was used to identify and apportion fine aerosols to their sources; bootstrapping was performed to determine the adequate number of PMF factors, and statistics (root mean square error, coefficient of determination, etc.) were examined to better model PM2.5 mass and chemical components. Potential source contribution function (PSCF) and conditional probability function (CPF) allowed the geographical origins of the sources to be assessed; special attention was paid to implement suitable weighting functions. Seven factors, namely ammonium sulfate (A.S.)-rich factor, ammonium nitrate (A.N.)-rich factor, heavy oil combustion, road traffic, biomass burning, marine aerosols and metal industry, were identified; a detailed discussion of their chemical characteristics is reported. They contribute 27, 24, 17, 14, 12, 6 and 1% of PM2.5 mass (14.7 μg m-3) respectively on the annual average; their seasonal variability is discussed. The A.S.- and A.N.-rich factors have undergone mid- or long-range transport from continental Europe; heavy oil combustion mainly stems from northern France and the English Channel, whereas road traffic and biomass burning are primarily locally emitted. Therefore, on average more than half of PM2.5 mass measured in the city of Paris is due to mid- or long-range transport of secondary aerosols stemming from continental Europe, whereas local sources only contribute a quarter of the annual averaged mass. These results imply that fine-aerosol abatement policies conducted at the local scale may not be sufficient to notably reduce PM2.5 levels at urban background sites in Paris, suggesting instead more coordinated strategies amongst neighbouring countries. Similar conclusions might be drawn in other continental urban background sites given the transboundary nature of PM2.5 pollution.

Fine Mapping of QUICK ROOTING 1 and 2, Quantitative Trait Loci Increasing Root Length in Rice.

PubMed

Kitomi, Yuka; Nakao, Emari; Kawai, Sawako; Kanno, Noriko; Ando, Tsuyu; Fukuoka, Shuichi; Irie, Kenji; Uga, Yusaku

2018-02-02

The volume that the root system can occupy is associated with the efficiency of water and nutrient uptake from soil. Genetic improvement of root length, which is a limiting factor for root distribution, is necessary for increasing crop production. In this report, we describe identification of two quantitative trait loci (QTLs) for maximal root length, QUICK ROOTING 1 ( QRO1 ) on chromosome 2 and QRO2 on chromosome 6, in cultivated rice ( Oryza sativa L.). We measured the maximal root length in 26 lines carrying chromosome segments from the long-rooted upland rice cultivar Kinandang Patong in the genetic background of the short-rooted lowland cultivar IR64. Five lines had longer roots than IR64. By rough mapping of the target regions in BC 4 F 2 populations, we detected putative QTLs for maximal root length on chromosomes 2, 6, and 8. To fine-map these QTLs, we used BC 4 F 3 recombinant homozygous lines. QRO1 was mapped between markers RM5651 and RM6107, which delimit a 1.7-Mb interval on chromosome 2, and QRO2 was mapped between markers RM20495 and RM3430-1, which delimit an 884-kb interval on chromosome 6. Both QTLs may be promising gene resources for improving root system architecture in rice. Copyright © 2018 Kitomi et al.

Soil respiration and root biomass responses to burning in calabrian pine (Pinus brutia) stands in Edirne, Turkey.

PubMed

Tufekcioglu, Aydin; Kucuk, Mehmet; Bilmis, Tuncay; Altun, Lokman; Yilmaz, Murat

2010-01-01

In this study soil properties and root biomass responses to prescribed fire were investigated in 25-30 year-old calabrian pine (Pinus brutia Ten.) stands in Edirne, Turkey. The stands were established by planting and were subjected to prescribed burning in July 2005. Soil respiration rates were determined every two months using the soda-lime method over a two-year period. Fine (> or = 2 mm diameter) and small root (> 2-5 mm diameter) biomass were sampled approximately bimonthly using the sequential coring method. Soil respiration rates in burned sites were significantly higher than in control sites during the summer season but there was no significant difference in the other seasons. Soil respiration rates were correlated significantly with soil moisture and soil temperature. Fine and small root biomass were significantly lower in burned sites than in control sites. Mean fine root biomass values were 3204 kg ha(-1) for burned and 3772 kg ha(-1) for control sites. Annual soil CO2 releases totaled 515 g Cm(-2) for burned and 418 g C m(-2) for control sites. Our results indicate that, depending on site conditions, fire could be used successfully as a tool in the management of calabrian pine stands in the study area.

Genetic Based Plant Resistance and Susceptibility Traits to Herbivory Influence Needle and Root Litter Nutrient Dynamics

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

Classen, Aimee T; Chapman, Samantha K.; Whitham, Thomas G

2007-01-01

It is generally assumed that leaf and root litter decomposition have similar drivers and that nutrient release from these substrates is synchronized. Few studies have examined these assumptions, and none has examined how plant genetics (i.e., plant susceptibility to herbivory) could affect these relationships. Here we examine the effects of herbivore susceptibility and resistance on needle and fine root litter decomposition of pi on pine, Pinus edulis. The study population consists of individual trees that are either susceptible or resistant to herbivory by the pi on needle scale, Matsucoccus acalyptus, or the stem-boring moth, Dioryctria albovittella. Genetic analyses and experimentalmore » removals and additions of these insects have identified trees that are naturally resistant and susceptible to these insects. These herbivores increase the chemical quality of litter inputs and alter soil microclimate, both of which are important decomposition drivers. Our research leads to four major conclusions: Herbivore susceptibility and resistance effects on 1) needle litter mass loss and phosphorus (P) retention in moth susceptible and resistant litter are governed by microclimate, 2) root litter nitrogen (N) and P retention, and needle litter N retention are governed by litter chemical quality, 3) net nutrient release from litter can reverse over time, 4) root and needle litter mass loss and nutrient release are determined by location (above- vs. belowground), suggesting that the regulators of needle and root decomposition differ at the local scale. Understanding of decomposition and nutrient retention in ecosystems requires consideration of herbivore effects on above- and belowground processes and how these effects may be governed by plant genotype. Because an underlying genetic component to herbivory is common to most ecosystems of the world and herbivory may increase in climatic change scenarios, it is important to evaluate the role of plant genetics in affecting carbon and nutrient fluxes.« less

Litter type control on soil C and N stabilization dynamics in a temperate forest.

PubMed

Hatton, Pierre-Joseph; Castanha, Cristina; Torn, Margaret S; Bird, Jeffrey A

2015-03-01

While plant litters are the main source of soil organic matter (SOM) in forests, the controllers and pathways to stable SOM formation remain unclear. Here, we address how litter type ((13) C/(15) N-labeled needles vs. fine roots) and placement-depth (O vs. A horizon) affect in situ C and N dynamics in a temperate forest soil after 5 years. Litter type rather than placement-depth controlled soil C and N retention after 5 years in situ, with belowground fine root inputs greatly enhancing soil C (x1.4) and N (x1.2) retention compared with aboveground needles. While the proportions of added needle and fine root-derived C and N recovered into stable SOM fractions were similar, they followed different transformation pathways into stable SOM fractions: fine root transfer was slower than for needles, but proportionally more of the remaining needle-derived C and N was transferred into stable SOM fractions. The stoichiometry of litter-derived C vs. N within individual SOM fractions revealed the presence at least two pools of different turnover times (per SOM fraction) and emphasized the role of N-rich compounds for long-term persistence. Finally, a regression approach suggested that models may underestimate soil C retention from litter with fast decomposition rates. © 2014 John Wiley & Sons Ltd.

Effect of drought on fine roots productivity in poplar-based short rotation coppice

NASA Astrophysics Data System (ADS)

Mani Tripathi, Abhishek; Fischer, Milan; Berhongaray, Gonzalo; Orság, Matěj; Trnka, Miroslav

2015-04-01

Short rotation woody crops (SRWC) are alternative source of bioenergy, which apart from their 'carbon neutrality' have potential to store carbon (C) into soil and mitigate the increasing CO2 emission. Studies of below ground biomass of trees are divided into two types according to root diameter - analysis of fine roots (less than 2 mm) and coarse roots (more than 2 mm). Trees roots are spatially highly heterogeneous and it requires large number of samples to obtain a representative estimate of belowground biomass. For this study we used hybrid poplar clone J-105 (Populus nigra x P. maximowiczii) grown under short rotation coppice system in the region of Bohemian-Moravian Highland (49o32'N, 16o15'E and altitude 530 m a.s.l.) since April 2000. The plantation with planting density of 9,216 trees ha-1 was established on the former agricultural land and the length of the rotation cycle was set to 6-8 years. While mean annual rainfall was 609 mm with mean annual temperature 7.2oC during 1981-2013 significant increase of temperature and more frequent droughts are expected. In 2011, we established drought experiment based on throughfall exclusion system, reducing up to 70 % of throughfall precipitation. Thus 2 treatments with normal and lowered soil moisture levels were introduced. In January and February 2014, we cored 18 places including drought and control using root bipartite auger. The main goal of the study is to assess the response of fine roots productivity and fine roots vertical distribution on the reduced soil water availability. Results will be presented at the conference. Acknowledgements: This study was funded by research project IGA Mendel University 2014 "Study of below ground biomass in short rotation poplar coppice (J-105) in the Czech-Moravian Highlands", project PASED (KONTAKT II LH12037 ʺDevelopment of models for the assessment of abiotic stresses in selected energy woody plantsʺ and "Building up a multidisciplinary scientific team focused on drought" No. CZ.1.07/2.3.00/20.0248.

Patterns of nocturnal rehydration in root tissues of Vaccinium corymbosum L. under severe drought conditions

PubMed Central

Valenzuela-Estrada, Luis R.; Richards, James H.; Diaz, Andres; Eissensat, David M.

2009-01-01

Although roots in dry soil layers are commonly rehydrated by internal hydraulic redistribution during the nocturnal period, patterns of tissue rehydration are poorly understood. Rates of nocturnal rehydration were examined in roots of different orders in Vaccinium corymbosum L. ‘Bluecrop’ (Northern highbush blueberry) grown in a split-pot system with one set of roots in relatively moist soil and the other set of roots in dry soil. Vaccinium is noted for a highly branched and extremely fine root system. It is hypothesized that nocturnal root tissue rehydration would be slow, especially in the distal root orders because of their greater hydraulic constraints (smaller vessel diameters and fewer number of vessels). Vaccinium root hydraulic properties delayed internal water movement. Even when water was readily available to roots in the wet soil and transpiration was minimal, it took a whole night-time period of 12 h for the distal finest roots (1st to 4th order) under dry soil conditions to reach the same water potentials as fine roots in moist soil (1st to 4th order). Even though roots under dry soil equilibrated with roots in moist soil, the equilibrium point reached before sunrise was about –1.2 MPa, indicating that tissues were not fully rehydrated. Using a single-branch root model, it was estimated that individual roots exhibiting the lowest water potentials in dry soil were 1st order roots (distal finest roots of the root system). However, considered at the branch level, root orders with the highest hydraulic resistances corresponded to the lowest orders of the permanent root system (3rd-, 4th-, and 5th-order roots), thus indicating possible locations of hydraulic safety control in the root system of this species. PMID:19188275

Patterns of nocturnal rehydration in root tissues of Vaccinium corymbosum L. under severe drought conditions.

PubMed

Valenzuela-Estrada, Luis R; Richards, James H; Diaz, Andres; Eissensat, David M

2009-01-01

Although roots in dry soil layers are commonly rehydrated by internal hydraulic redistribution during the nocturnal period, patterns of tissue rehydration are poorly understood. Rates of nocturnal rehydration were examined in roots of different orders in Vaccinium corymbosum L. 'Bluecrop' (Northern highbush blueberry) grown in a split-pot system with one set of roots in relatively moist soil and the other set of roots in dry soil. Vaccinium is noted for a highly branched and extremely fine root system. It is hypothesized that nocturnal root tissue rehydration would be slow, especially in the distal root orders because of their greater hydraulic constraints (smaller vessel diameters and fewer number of vessels). Vaccinium root hydraulic properties delayed internal water movement. Even when water was readily available to roots in the wet soil and transpiration was minimal, it took a whole night-time period of 12 h for the distal finest roots (1st to 4th order) under dry soil conditions to reach the same water potentials as fine roots in moist soil (1st to 4th order). Even though roots under dry soil equilibrated with roots in moist soil, the equilibrium point reached before sunrise was about -1.2 MPa, indicating that tissues were not fully rehydrated. Using a single-branch root model, it was estimated that individual roots exhibiting the lowest water potentials in dry soil were 1st order roots (distal finest roots of the root system). However, considered at the branch level, root orders with the highest hydraulic resistances corresponded to the lowest orders of the permanent root system (3rd-, 4th-, and 5th-order roots), thus indicating possible locations of hydraulic safety control in the root system of this species.

Simulated root dynamics of a 160-year-old sugar maple (Acer saccharum Marsh.) tree with and without ozone exposure using the TREGRO model.

PubMed

Retzlaff, W. A.; Weinstein, D. A.; Laurence, J. A.; Gollands, B.

1996-01-01

Because of difficulties in directly assessing root responses of mature forest trees exposed to atmospheric pollutants, we have used the model TREGRO to analyze the effects of a 3- and a 10-year exposure to ozone (O(3)) on root dynamics of a simulated 160-year-old sugar maple (Acer saccharum Marsh.) tree. We used existing phenological, allometric, and growth data to parameterize TREGRO to produce a simulated 160-year-old tree. Simulations were based on literature values for sugar maple fine root production and senescence and the photosynthetic responses of sugar maple seedlings exposed to O(3) in open-top chambers. In the simulated 3-year exposure to O(3), 2 x ambient atmospheric O(3) concentrations reduced net carbon (C) gain of the 160-year-old tree. This reduction occurred in the C storage pools (total nonstructural carbohydrate, TNC), with most of the reduction occurring in coarse (woody) roots. Total fine root production and senescence were unaffected by the simulated 3-year exposure to O(3). However, extending the simulated O(3) exposure period to 10 years depleted the TNC pools of the coarse roots and reduced total fine root production. Similar reductions in TNC pools have been observed in forest-grown sugar maple trees exhibiting symptoms of stress. We conclude that modeling can aid in evaluating the belowground response of mature forest trees to atmospheric pollution stress and could indicate the potential for gradual deterioration of tree health under conditions of long-term stress, a situation similar to that underlying the decline of sugar maple trees.

Influence of repeated prescribed fire and herbicide application on the fine root biomass of young longleaf pine

Treesearch

Mary Anne Sword Sayer; Eric A. Kuehler

2010-01-01

Photosynthate from mature foliage provides the energy source necessary for longleaf pine (Pinus palustris Mill.) root system expansion. Crown scorch caused by repeated prescribed fire could decrease this energy and, in turn, reduce new root production. We conducted a study to assess the root biomass of restored longleaf pine saplings in response to...

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...

Root respiration in North American forests: Effects of nitrogen concentration and temperature across biomes

Treesearch

A.J. Burton; K.S. Pregitzer; R.W. Ruess; R.L. Hendrick; Mike F. Allen

2002-01-01

Root respiration rates have been shown to be correlated with temperature and root N concentration in studies of individual forest types or species, but it is not known how universal these relationships are across forest species adapted to widely different climatic and edaphic conditions. In order to test for broad, cross-species relationships, we measured fine root...

Automatic discrimination of fine roots in minirhizotron images.

PubMed

Zeng, Guang; Birchfield, Stanley T; Wells, Christina E

2008-01-01

Minirhizotrons provide detailed information on the production, life history and mortality of fine roots. However, manual processing of minirhizotron images is time-consuming, limiting the number and size of experiments that can reasonably be analysed. Previously, an algorithm was developed to automatically detect and measure individual roots in minirhizotron images. Here, species-specific root classifiers were developed to discriminate detected roots from bright background artifacts. Classifiers were developed from training images of peach (Prunus persica), freeman maple (Acer x freemanii) and sweetbay magnolia (Magnolia virginiana) using the Adaboost algorithm. True- and false-positive rates for classifiers were estimated using receiver operating characteristic curves. Classifiers gave true positive rates of 89-94% and false positive rates of 3-7% when applied to nontraining images of the species for which they were developed. The application of a classifier trained on one species to images from another species resulted in little or no reduction in accuracy. These results suggest that a single root classifier can be used to distinguish roots from background objects across multiple minirhizotron experiments. By incorporating root detection and discrimination algorithms into an open-source minirhizotron image analysis application, many analysis tasks that are currently performed by hand can be automated.

Effects of Crown Scorch on Longleaf Pine Fine Roots

Treesearch

Mary Anne Sword; James D. Haywood

1999-01-01

Photosynthate production is reduced by foliage loss. Thus, scorch-induced decreases in the leaf area of longleaf pine (Pinus palustris Mill.) may reduce photosynthate allocation to roots. In this investigation the root carbohydrate concentrations and dynamics of longleaf pine after two intensities of prescribed burning were monitored. In...

Combined effects of thinning and decline on fine root dynamics in a Quercus robur L. forest adjoining the Italian Pre-Alps.

PubMed

Mosca, E; Montecchio, L; Barion, G; Dal Cortivo, C; Vamerali, T

2017-05-01

Oak decline is a complex phenomenon, characterized by symptoms of canopy transparency, bark cracks and root biomass reduction. Root health status is one of the first stress indicators, and root turnover is a key process in plant adaptation to unfavourable conditions. In this study, the combined effects of decline and thinning were evaluated on fine root dynamics in an oak forest adjoining the Italian Pre-Alps by comparison of acute declining trees with non-declining trees, both with and without thinning treatment of surrounding trees. Dynamics of volumetric root length density (RLD V ) and tip density (RTD V ), root tip density per unit length of root (RTD L ), diameter, branching index (BI) and mycorrhizal colonization were monitored by soil coring over 2 years as possible descriptors of decline. At the beginning of the experiment, the relationship between canopy transparency and root status was weak, declining trees having slightly lower RLD V (-20 %) and RTD V (-11 %). After a 1 year lag, during which the parameters were almost unaffected, BI and RLD V , together with tip density, tip vitality and mycorrhizal colonization, became the descriptors most representative of both decline class and thinning. Thinning of declining trees increased RLD V (+12 %) and RTD V (+32 %), but reduced tip mycorrhizal colonization and vitality over time compared with non-thinned trees, whereas the opposite occurred in healthy trees, together with a marked decrease in branching. After thinning, there was an initial reduction in the structure of the ectomycorrhizal community, although recovery occurred about 10 months later, regardless of decline severity. Decline causes losses of fine root length, and a moderate recovery can be achieved by thinning, allowing better soil exploration by oak roots. The close correlation between root vitality and mycorrhizal colonization and their deterioration after thinning indicates that decline does not benefit from reduced root competition, excluding the hypothesis of limited water and nutrient availability as a possible cause of the syndrome in this forest. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Combined effects of thinning and decline on fine root dynamics in a Quercus robur L. forest adjoining the Italian Pre-Alps

PubMed Central

Montecchio, L.; Barion, G.; Dal Cortivo, C.; Vamerali, T.

2017-01-01

Abstract Aims Oak decline is a complex phenomenon, characterized by symptoms of canopy transparency, bark cracks and root biomass reduction. Root health status is one of the first stress indicators, and root turnover is a key process in plant adaptation to unfavourable conditions. In this study, the combined effects of decline and thinning were evaluated on fine root dynamics in an oak forest adjoining the Italian Pre-Alps by comparison of acute declining trees with non-declining trees, both with and without thinning treatment of surrounding trees. Methods Dynamics of volumetric root length density (RLDV) and tip density (RTDV), root tip density per unit length of root (RTDL), diameter, branching index (BI) and mycorrhizal colonization were monitored by soil coring over 2 years as possible descriptors of decline. Key Results At the beginning of the experiment, the relationship between canopy transparency and root status was weak, declining trees having slightly lower RLDV (–20 %) and RTDV (–11 %). After a 1 year lag, during which the parameters were almost unaffected, BI and RLDV, together with tip density, tip vitality and mycorrhizal colonization, became the descriptors most representative of both decline class and thinning. Thinning of declining trees increased RLDV (+12 %) and RTDV (+32 %), but reduced tip mycorrhizal colonization and vitality over time compared with non-thinned trees, whereas the opposite occurred in healthy trees, together with a marked decrease in branching. After thinning, there was an initial reduction in the structure of the ectomycorrhizal community, although recovery occurred about 10 months later, regardless of decline severity. Conclusions Decline causes losses of fine root length, and a moderate recovery can be achieved by thinning, allowing better soil exploration by oak roots. The close correlation between root vitality and mycorrhizal colonization and their deterioration after thinning indicates that decline does not benefit from reduced root competition, excluding the hypothesis of limited water and nutrient availability as a possible cause of the syndrome in this forest. PMID:28334145

The Integrated Role of Water Availability, Nutrient Dynamics, and Xylem Hydraulic Dysfunction on Plant Rooting Strategies in Managed and Natural Ecosystems

NASA Astrophysics Data System (ADS)

Mackay, D. S.; Savoy, P.; Pleban, J. R.; Tai, X.; Ewers, B. E.

2015-12-01

Plants adapt or acclimate to changing environments in part by allocating biomass to roots and leaves to strike a balance between water and nutrient uptake requirements on the one hand and growth and hydraulic safety on the other hand. In a recent study examining experimental drought with the TREES model, which couples plant ecophysiology with rhizosphere-and-xylem hydraulics, we hypothesized that the asynchronous nature of soil water availability and xylem repair supported root-to-leaf area (RLA) proportionality that favored long-term survival over short-term carbon gain or water use. To investigate this as a possible general principal of plant adjustment to changing environmental conditions, TREES was modified to allocate carbon to fine and coarse roots organized in ten orders differing in biomass allocated per unit absorbing root area, root lifespan, and total absorbing root area in each of several soil-root zones with depth. The expanded model allowed for adjustment of absorbing root area and rhizosphere volume based on available carbohydrate production and nitrogen (N) availability, resulting in dynamic expansion and contraction of the supply-side of the rhizosphere-plant hydraulics and N uptake capacity in response to changing environmental conditions and plant-environment asynchrony. The study was conducted partly in a controlled experimental setting with six genotypes of a widely grown crop species, Brassica rapa. The implications for forests were investigated in controlled experiments and at Fluxnet sites representing temperate mixed forests, semi-arid evergreen needle-leaf, and Mediterranean biomes. The results showed that the effects of N deficiency on total plant growth was modulated by a relative increase in fine root biomass representing a larger absorbing root volume per unit biomass invested. We found that the total absorbing root area per unit leaf area was consistently lower than that needed to maximize short-term water uptake and carbohydrate gain. Moreover, the acclimated RLA fell within a small range for both crops and trees despite changing environmental conditions, demonstrating an adaptation that was consistent with empiricism on fine roots and thus pointing to a fundamental connection between ecological and hydrological processes.

Phloem Girdling of Norway Spruce Alters Quantity and Quality of Wood Formation in Roots Particularly Under Drought

PubMed Central

Rainer-Lethaus, Gina; Oberhuber, Walter

2018-01-01

Carbon (C) availability plays an essential role in tree growth and wood formation. We evaluated the hypothesis that a decrease in C availability (i) triggers mobilization of C reserves in the coarse roots of Picea abies to maintain growth and (ii) causes modification of wood structure notably under drought. The 6-year-old saplings were subjected to two levels of soil moisture (watered versus drought conditions) and root C status was manipulated by physically blocking phloem transport in the stem at three girdling dates (GDs). Stem girdling was done before the onset of bud break [day of the year (doy) 77], during vigorous aboveground shoot and radial stem growth (GD doy 138), and after cessation of shoot growth (GD doy 190). The effect of blockage of C transport on root growth, root phenology, and wood anatomical traits [cell lumen diameter (CLD) and cell wall thickness (CWT)] in earlywood (EW) and latewood (LW) was determined. To evaluate changes in belowground C status caused by girdling, non-structural carbohydrates (soluble sugars and starch) in coarse roots were determined at the time of girdling and after the growing season. Although fine root mass significantly decreased in response to blockage of phloem C transport, the phenology of root elongation growth was not affected. Surprisingly, radial root growth and CLD of EW tracheids in coarse roots were strikingly increased in drought-stressed trees, when girdling occurred before bud break or during aboveground stem growth. In watered trees, the growth response to girdling was less distinct, but the CWT of EW significantly increased. Starch reserves in the roots of girdled trees significantly decreased in both soil moisture treatments and at all GDs. We conclude that (i) radial growth and wood development in coarse roots of P. abies saplings are not only dependent on current photosynthates, and (ii) blockage of phloem transport induces physiological changes that outweigh drought effects imposed on root cambial activity and cell differentiation. PMID:29636766

Impact of post-mining subsidence on nitrogen transformation in southern tropical dry deciduous forest, India

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

Tripathi, N.; Singh, R.S.; Singh, J.S.

The goal of our research was to assess the impact of post-mining land subsidence, caused due to underground coal mining operations, on fine root biomass and root tips count; plant available nutrient status, microbial biomass N (MBN) and N-mineralization rates of a Southern tropical dry deciduous forest of Singareni Coalfields of India. The changes were quantified in all the three (rainy, winter and summer) seasons, in slope and depression microsites of the subsided land and an adjacent undamaged forest microsite. Physico-chemical characteristics were found to be altered after subsidence, showing a positive impact of subsidence on soil moisture, bulk density,more » water holding capacity, organic carbon content, total N and total P. The increase in all the parameters was found in depression microsites, while in slope microsites, the values were lower. Fine root biomass and root tips count increased in the subsided depression microsites, as demonstrated by increases of 62% and 45%, respectively. Soil nitrate-N and phosphate-P concentrations were also found to be higher in depression microsite, showing an increase of 35.68% and 24.74%, respectively. Depression microsite has also shown the higher MBN value with an increase over control. Net nitrification, net N-mineralization and MBN were increased in depression microsite by 29.77%, 25.72% and 34%, respectively. There was a positive relation of microbial N with organic C, fine root biomass and root tips.« less

Effect of organic matter and roots in soil respiration in a Mediterranean riparian areas in Central Spain

NASA Astrophysics Data System (ADS)

Gonzalez-Garrido, Laura; Delgado, Juan Antonio; Martinez, Teodora

2010-05-01

Soil respiration is one of the largest carbon flux components within terrestrial ecosystems, and small changes in the magnitude of soil respiration could have a large effect on the concentration of CO2 in the atmosphere. The main objective is evaluating the factors controlling soil respiration on the global carbon cycle in riparian areas of Henares River. We evaluated total soil respiration as it was affected by soil temperature, soil moisture, root respiration and organic matter in four areas differing in vegetation cover. We specifically assessed the contribution of soil organic matter and fine root biomass (≤1 mm.) in soil carbon dioxide flux. The study area is located on the riverbanks of Henares River where it passes through the municipal term of Alcala de Henares (Madrid) in Central Spain. Measurements were performed in spring and autumn of 2009. The study was conducted on four different types of riparian vegetation: natural Mediterranean riparian forest, reforestation of 1994, reforestation of 1999 and riparian grassland without trees. In each area of study 3, 25x25 m, plots were delimited and within each plot three sampling units of 50x50 cm were selected at random. The temperature of the ground was taken during the measures from respiration using a Multi-thermometer (-50°C - +300°C) at 5 cm depth. The moisture content of the ground was measured at 5 cm of depth with a HH2 Moisture meter (Delta Devices, Cambridge, UK). The measures of respiration of the ground were realised in field by means of LCI portable (LC pro ADC Bioscientific, Ltd. UK) connected to a ground respiration camera. We introduced the camera 3 cm into the soil just after eliminating the vegetation grass of the surface of measurement cutting carefully the aerial part, without damaging the roots. Soil CO2 flux measurements were registered after stabilization. Immediately after CO2 measurements, we obtained soil samples by means of a drill of 2.18 cm of diameter taking samples to 10 cm and 20 cm depth. Soil samples were dried to the air with the aim of preserving the roots the sample contained. They were extracted manually by means of very fine tweezers. We separate roots by diameter (Fine roots ≤ 1mm; rest of roots > 1mm) and dead from alive using texture and colour as clues. Finally the dry weight of roots was taking with a precision balance +-0.0001. Soil organic matter to 10 and 20 cm of depth were measure in laboratory using the method of Walkley and Black (1934). Differences in Soil CO2 flux, organic matter, fine root biomass, temperature and moisture between areas were analyzed using one-way ANOVAs. Our results suggest that fine root biomass present a larger impact than soil organic matter in soil CO2 flux values. Natural riparian forest presented higher values of soil CO2 flux than the rest of areas even when differences in root biomass and soil organic matter were controlled. Between the grassy area and both reforestations there were no differences in soil CO2 flux. In addition, we found that soil CO2 flux in our study area was more affected by soil temperature than by moisture, which could be relevant in the interpretation of the possible effects of global change. Key words: riparian forest, fine roots, carbon cycle, soil CO2 flux, root respiration. Acknowledgements: Research projects, n°FP08-AG02 IMIDRA and RTA 2006-00101-00-00 INIA and predoctoral scholarship FPI-INIA.

Root Morphology Was Improved in a Late-Stage Vigor Super Rice Cultivar.

PubMed

Huang, Min; Chen, Jiana; Cao, Fangbo; Jiang, Ligeng; Zou, Yingbin

2015-01-01

This study aimed to test the hypothesis that root morphology might be improved and consequently contributing to superior post-heading shoot growth and grain yield in late-stage vigor super rice. A pot experiment was carried out to compare yield attributes, shoot growth and physiological properties and root morphological traits between a late-stage vigor super rice cultivar (Y-liangyou 087) and an elite rice cultivar (Teyou 838). Grain yield and total shoot biomass were 7-9% higher in Y-liangyou 087 than in Teyou 838. Y-liangyou 087 had 60-64% higher post-heading shoot growth rate and biomass production than Teyou 838. Average relative chlorophyll concentration and net photosynthetic rate in flag leaves were 7-11% higher in Y-liangyou 087 than in Teyou 838 during heading to 25 days after heading. Y-liangyou 087 had 41% higher post-heading shoot N uptake but 17-25% lower root biomass and root-shoot ratio at heading and maturity than Teyou 838. Specific root length and length and surface area of fine roots were higher in Y-liangyou 087 than in Teyou 838 at heading and maturity by more than 15%. These results indicated that root-shoot relationships were well balanced during post-heading phase in the late-stage vigor super rice cultivar Y-liangyou 087 by improving root morphology including avoiding a too great root biomass and developing a large fine root system.

Advancing the use of minirhizotrons in wetlands

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

Iversen, Colleen M; Murphy, Meaghan T.; Allen, Michael F.

Background: Wetlands store a substantial amount of carbon (C) in deep soil organic matter deposits, and play an important role in global fluxes of carbon dioxide and methane. Fine roots (i.e., ephemeral roots that are active in water and nutrient uptake) are recognized as important components of biogeochemical cycles in nutrient-limited wetland ecosystems. However, quantification of fine-root dynamics in wetlands has generally been limited to destructive approaches, possibly because of methodological difficulties associated with the unique environmental, soil, and plant community characteristics of these systems. Non-destructive minirhizotron technology has rarely been used in wetland ecosystems. Scope: Our goal was tomore » develop a consensus on, and a methodological framework for, the appropriate installation and use of minirhizotron technology in wetland ecosystems. Here, we discuss a number of potential solutions for the challenges associated with the deployment of minirhizotron technology in wetlands, including minirhizotron installation and anchorage, capture and analysis of minirhizotron images, and upscaling of minirhizotron data for analysis of biogeochemical pools and parameterization of land surface models. Conclusions: The appropriate use of minirhizotron technology to examine relatively understudied fine-root dynamics in wetlands will advance our knowledge of ecosystem C and nutrient cycling in these globally important ecosystems.« less

Advancing Understanding of the Role of Belowground Processes in Terrestrial Carbon Sinks trhrough Ground-Penetrating Radar. Final Report

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

Day, Frank P.

2015-02-06

Coarse roots play a significant role in belowground carbon cycling and will likely play an increasingly crucial role in belowground carbon sequestration as atmospheric CO 2 levels continue to rise, yet they are one of the most difficult ecosystem parameters to quantify. Despite promising results with ground-penetrating radar (GPR) as a nondestructive method of quantifying biomass of coarse roots, this application of GPR is in its infancy and neither the complete potential nor limitations of the technology have been fully evaluated. The primary goals and questions of this study fell into four groups: (1) GPR methods: Can GPR detect changemore » in root biomass over time, differentiate live roots from dead roots, differentiate between coarse roots, fine roots bundled together, and a fine root mat, remain effective with varied soil moisture, and detect shadowed roots (roots hidden below larger roots); (2) CO 2 enrichment study at Kennedy Space Center in Brevard County, Florida: Are there post-fire legacy effects of CO 2 fertilization on plant carbon pools following the end of CO 2application ? (3) Disney Wilderness Study: What is the overall coarse root biomass and potential for belowground carbon storage in a restored longleaf pine flatwoods system? Can GPR effectively quantify coarse roots in soils that are wetter than the previous sites and that have a high percentage of saw palmetto rhizomes present? (4) Can GPR accurately represent root architecture in a three-dimensional model? When the user is familiar with the equipment and software in a setting that minimizes unsuitable conditions, GPR is a relatively precise, non-destructive, useful tool for estimating coarse root biomass. However, there are a number of cautions and guidelines that should be followed to minimize inaccuracies or situations that are untenable for GPR use. GPR appears to be precise as it routinely predicts highly similar values for a given area across multiple scanning events; however, it appears to lack sufficient accuracy at small scales. Knowledge of soil conditions and their effects on GPR wave propagation and reception are paramount for the collection of useful data. Strong familiarity with the software and equipment is both important and necessary for GPR use in estimating coarse root biomass. GPR must be utilized at low soil moisture levels in order to accurately represent existing coarse root structures. Our results from Disney Wilderness Preserve highlight the need for a strong understanding of the limitations of GPR, specifically knowledge of root structures (saw palmetto rhizomes) or environmental factors (low moisture content) that may hinder its application within a given system. The 3D modeling of course roots with GPR appears quite promising, as it has become more accurate and precise as the software has advanced and become more robust, but there is still a need for more precision before it will likely be able to model anything more than simple root systems comprised mostly of large diameter roots. Our results from Kennedy Space Center suggest that there are legacy effects from CO 2 fertilization in the form of more root mass providing a greater capacity for aboveground plant regrowth following fire, even 7 years after treatment ended.« less

Root desiccation and drought stress responses of bareroot Quercus rubra seedlings treated with a hydrophilic polymer root dip

Treesearch

Kent G. Apostol; Douglass F. Jacobs; R. Kasten Dumroese

2009-01-01

Root hydrogel, a hydrophilic polymer, has been used to improve transplanting success of bareroot conifer seedlings through effects on water holding capacity. We examined mechanisms by which Terra-sorb Fine Hydrogel reduces damage that occurs when roots of 1-year old, dormant northern red oak (Quercus rubra L.) were subjected to shortterm (1, 3, and 5...

Mechanical failure of fine root cortical cells initiates plant hydraulic decline during drought

USDA-ARS?s Scientific Manuscript database

Root systems perform the crucial task of absorbing water from the soil to meet the demands of a transpiring canopy. Roots are thought to operate like electrical fuses, which break when carrying an excessive load under conditions of drought stress. Yet the exact site and sequence of this dysfunction ...

PATTERNS OF ROOT GROWTH, TURNOVER, AND DISTRIBUTION IN DIFFERENT AGED PONDEROSA PINE STANDS

EPA Science Inventory

The objectives of this study are to examine the spatial distribution of roots in relation to canopy size and tree distribution, and to determine if rates of fine root production and turnover are similar in the different aged stands. During the fall of 1998, 54 clear plexiglass t...

CONTRIBUTIONS OF CURRENT YEAR PHOTOSYNTHATE TO FINE ROOTS ESTIMATED USING A 13C-DEPLETED CO2 SOURCE

EPA Science Inventory

The quantification of root turnover is necessary for a complete understanding of plant carbon (C) budgets, especially in terms of impacts of global climate change. To improve estimates of root turnover, we present a method to distinguish current- from prior-year allocation of ca...

FINE ROOT TURNOVER IN PONDEROSA PINE STANDS OF DIFFERENT AGES: FIRST-YEAR RESULTS

EPA Science Inventory

Root minirhizotron tubs were installed in two ponderosa pine (Pinus ponderosa Laws.) Stands of different ages to examine patterns of root growth and death. The old-growth site (OS) consists of a mixture of old (>250 years) and young trees (ca.45 yrs)< and is located near clamp S...

The ectomycorrhizal community of conifer stands on peat soils 12 years after fertilization with wood ash.

PubMed

Klavina, Darta; Pennanen, Taina; Gaitnieks, Talis; Velmala, Sannakajsa; Lazdins, Andis; Lazdina, Dagnija; Menkis, Audrius

2016-02-01

We studied long-term effects of fertilization with wood ash on biomass, vitality and mycorrhizal colonization of fine roots in three conifer forest stands growing in Vacciniosa turf. mel. (V), Myrtillosa turf. mel. (M) and Myrtillosa turf. mel./Caricoso-phragmitosa (MC) forest types on peat soils. Fertilization trials amounting 5 kg/m(2) of wood ash were established 12 years prior to this study. A total of 63 soil samples with roots were collected and analysed. Ectomycorrhizal (ECM) fungi in roots were identified by morphotyping and sequencing of the fungal internal transcribed spacer (ITS) region. In all forest types, fine root biomass was higher in fertilized plots than in control plots. In M forest type, proportion of living fine roots was greater in fertilized plots than in control plots, while in V and MC, the result was opposite. Fifty ECM species were identified, of which eight were common to both fertilized and control plots. Species richness and Shannon diversity index were generally higher in fertilized plots than in control plots. The most common species in fertilized plots were Amphinema byssoides (17.8%) and Tuber cf. anniae (12.2%), while in control plots, it was Tylospora asterophora (18.5%) and Lactarius tabidus (20.3%). Our results showed that forest fertilization with wood ash has long-lasting effect on diversity and composition of ECM fungal communities.

Arbuscular mycorrhizas are present on Spitsbergen.

PubMed

Newsham, K K; Eidesen, P B; Davey, M L; Axelsen, J; Courtecuisse, E; Flintrop, C; Johansson, A G; Kiepert, M; Larsen, S E; Lorberau, K E; Maurset, M; McQuilkin, J; Misiak, M; Pop, A; Thompson, S; Read, D J

2017-10-01

A previous study of 76 plant species on Spitsbergen in the High Arctic concluded that structures resembling arbuscular mycorrhizas were absent from roots. Here, we report a survey examining the roots of 13 grass and forb species collected from 12 sites on the island for arbuscular mycorrhizal (AM) colonisation. Of the 102 individuals collected, we recorded AM endophytes in the roots of 41 plants of 11 species (Alopecurus ovatus, Deschampsia alpina, Festuca rubra ssp. richardsonii, putative viviparous hybrids of Poa arctica and Poa pratensis, Poa arctica ssp. arctica, Trisetum spicatum, Coptidium spitsbergense, Ranunculus nivalis, Ranunculus pygmaeus, Ranunculus sulphureus and Taraxacum arcticum) sampled from 10 sites. Both coarse AM endophyte, with hyphae of 5-10 μm width, vesicles and occasional arbuscules, and fine endophyte, consisting of hyphae of 1-3 μm width and sparse arbuscules, were recorded in roots. Coarse AM hyphae, vesicles, arbuscules and fine endophyte hyphae occupied 1.0-30.7, 0.8-18.3, 0.7-11.9 and 0.7-12.8% of the root lengths of colonised plants, respectively. Principal component analysis indicated no associations between the abundances of AM structures in roots and edaphic factors. We conclude that the AM symbiosis is present in grass and forb roots on Spitsbergen.

Quantitative Classification of Rice (Oryza sativa L.) Root Length and Diameter Using Image Analysis.

PubMed

Gu, Dongxiang; Zhen, Fengxian; Hannaway, David B; Zhu, Yan; Liu, Leilei; Cao, Weixing; Tang, Liang

2017-01-01

Quantitative study of root morphological characteristics of plants is helpful for understanding the relationships between their morphology and function. However, few studies and little detailed and accurate information of root characteristics were reported in fine-rooted plants like rice (Oryza sativa L.). The aims of this study were to quantitatively classify fine lateral roots (FLRs), thick lateral roots (TLRs), and nodal roots (NRs) and analyze their dynamics of mean diameter (MD), lengths and surface area percentage with growth stages in rice plant. Pot experiments were carried out during three years with three rice cultivars, three nitrogen (N) rates and three water regimes. In cultivar experiment, among the three cultivars, root length of 'Yangdao 6' was longest, while the MD of its FLR was the smallest, and the mean diameters for TLR and NR were the largest, the surface area percentage (SAP) of TLRs (SAPT) was the highest, indicating that Yangdao 6 has better nitrogen and water uptake ability. High N rate increased the length of different types of roots and increased the MD of lateral roots, decreased the SAP of FLRs (SAPF) and TLRs, but increased the SAP of NRs (SAPN). Moderate decrease of water supply increased root length and diameter, water stress increased the SAPF and SAPT, but decreased SAPN. The quantitative results indicate that rice plant tends to increase lateral roots to get more surface area for nitrogen and water uptake when available assimilates are limiting under nitrogen and water stress environments.

Quantitative Classification of Rice (Oryza sativa L.) Root Length and Diameter Using Image Analysis

PubMed Central

Gu, Dongxiang; Zhen, Fengxian; Hannaway, David B.; Zhu, Yan; Liu, Leilei; Cao, Weixing; Tang, Liang

2017-01-01

Quantitative study of root morphological characteristics of plants is helpful for understanding the relationships between their morphology and function. However, few studies and little detailed and accurate information of root characteristics were reported in fine-rooted plants like rice (Oryza sativa L.). The aims of this study were to quantitatively classify fine lateral roots (FLRs), thick lateral roots (TLRs), and nodal roots (NRs) and analyze their dynamics of mean diameter (MD), lengths and surface area percentage with growth stages in rice plant. Pot experiments were carried out during three years with three rice cultivars, three nitrogen (N) rates and three water regimes. In cultivar experiment, among the three cultivars, root length of ‘Yangdao 6’ was longest, while the MD of its FLR was the smallest, and the mean diameters for TLR and NR were the largest, the surface area percentage (SAP) of TLRs (SAPT) was the highest, indicating that Yangdao 6 has better nitrogen and water uptake ability. High N rate increased the length of different types of roots and increased the MD of lateral roots, decreased the SAP of FLRs (SAPF) and TLRs, but increased the SAP of NRs (SAPN). Moderate decrease of water supply increased root length and diameter, water stress increased the SAPF and SAPT, but decreased SAPN. The quantitative results indicate that rice plant tends to increase lateral roots to get more surface area for nitrogen and water uptake when available assimilates are limiting under nitrogen and water stress environments. PMID:28103264

Effects of soil nutrient heterogeneity on intraspecific competition in the invasive, clonal plant Alternanthera philoxeroides.

PubMed

Zhou, Jian; Dong, Bi-Cheng; Alpert, Peter; Li, Hong-Li; Zhang, Ming-Xiang; Lei, Guang-Chun; Yu, Fei-Hai

2012-03-01

Fine-scale, spatial heterogeneity in soil nutrient availability can increase the growth of individual plants, the productivity of plant communities and interspecific competition. If this is due to the ability of plants to concentrate their roots where nutrient levels are high, then nutrient heterogeneity should have little effect on intraspecific competition, especially when there are no genotypic differences between individuals in root plasticity. We tested this hypothesis in a widespread, clonal species in which individual plants are known to respond to nutrient heterogeneity. Plants derived from a single clone of Alternanthera philoxeroides were grown in the greenhouse at low or high density (four or 16 plants per 27·5 × 27·5-cm container) with homogeneous or heterogeneous availability of soil nutrients, keeping total nutrient availability per container constant. After 9 weeks, measurements of size, dry mass and morphology were taken. Plants grew more in the heterogeneous than in the homogeneous treatment, showing that heterogeneity promoted performance; they grew less in the high- than in the low-density treatment, showing that plants competed. There was no interactive effect of nutrient heterogeneity and plant density, supporting the hypothesis that heterogeneity does not affect intraspecific competition in the absence of genotypic differences in plasticity. Treatments did not affect morphological characteristics such as specific leaf area or root/shoot ratio. Results indicate that fine-scale, spatial heterogeneity in the availability of soil nutrients does not increase competition when plants are genetically identical, consistent with the suggestion that effects of heterogeneity on competition depend upon differences in plasticity between individuals. Heterogeneity is only likely to increase the spread of monoclonal, invasive populations such as that of A. philoxeroides in China.

On the Control of Solute Mass Fluxes and Concentrations Below Fields Irrigated With Low-Quality Water: A Numerical Study

NASA Astrophysics Data System (ADS)

Russo, David

2017-11-01

The main goal of this study was to test the capability of irrigation water-based and soil-based approaches to control nitrate and chloride mass fluxes and concentrations below the root zone of agricultural fields irrigated with treated waste water (TWW). Using numerical simulations of flow and transport in relatively a fine-textured, unsaturated, spatially heterogeneous, flow domain, scenarios examined include: (i) irrigating with TWW only (REF); (ii) irrigation water is substituted between TWW and desalinized water (ADW); (iii) soil includes a capillary barrier (CB) and irrigating with TWW only (CB + TWW); and (iv) combination of (ii) and a CB (CB + ADW). Considering groundwater quality protection, plausible goals are: (i) to minimize solute discharges leaving the root zone, and, (ii) to maximize the probability that solute concentrations leaving the root zone will not exceed a prescribed, critical value. Results of the analyses suggest that in the case of a seasonal crop (a corn field) subject to irrigations only, with respect to the first goal, the CB + TWW and CB + ADW scenarios provide similar, excellent results, better than the ADW scenario; with respect to the second goal, however, the CB + ADW scenario gave substantially better results than the CB + TWW scenario. In the case a multiyear, perennial crop (a citrus orchard), subject to a sequence of irrigation and rainfall periods, for both solutes, and, particularly, nitrate, with respect to the two goals, both the ADW and CB + ADW scenarios perform better than the CB + TWW scenario. As compared with the REF and CB + TWW scenarios, the ADW and CB + ADW scenarios substantially reduce nitrogen mass fluxes to the groundwater and to the atmosphere, and, essentially, did not reduce nitrogen mass fluxes to the trees. Similar results, even better, were demonstrated for a relatively coarse-textured, spatially heterogeneous soil.

Comparison of mandibular first molar mesial root canal morphology using micro-computed tomography and clearing technique.

PubMed

Kim, Yeun; Perinpanayagam, Hiran; Lee, Jong-Ki; Yoo, Yeon-Jee; Oh, Soram; Gu, Yu; Lee, Seung-Pyo; Chang, Seok Woo; Lee, Woocheol; Baek, Seung-Ho; Zhu, Qiang; Kum, Kee-Yeon

2015-08-01

Micro-computed tomography (MCT) with alternative image reformatting techniques shows complex and detailed root canal anatomy. This study compared two-dimensional (2D) and 3D MCT image reformatting with standard tooth clearing for studying mandibular first molar mesial root canal morphology. Extracted human mandibular first molar mesial roots (n=31) were scanned by MCT (Skyscan 1172). 2D thin-slab minimum intensity projection (TS-MinIP) and 3D volume rendered images were constructed. The same teeth were then processed by clearing and staining. For each root, images obtained from clearing, 2D, 3D and combined 2D and 3D techniques were examined independently by four endodontists and categorized according to Vertucci's classification. Fine anatomical structures such as accessory canals, intercanal communications and loops were also identified. Agreement among the four techniques for Vertucci's classification was 45.2% (14/31). The most frequent were Vertucci's type IV and then type II, although many had complex configurations that were non-classifiable. Generally, complex canal systems were more clearly visible in MCT images than with standard clearing and staining. Fine anatomical structures such as intercanal communications, accessory canals and loops were mostly detected with a combination of 2D TS-MinIP and 3D volume-rendering MCT images. Canal configurations and fine anatomic structures were more clearly observed in the combined 2D and 3D MCT images than the clearing technique. The frequency of non-classifiable configurations demonstrated the complexity of mandibular first molar mesial root canal anatomy.

Soil properties and root biomass responses to prescribed burning in young Corsican pine (Pinus nigra Arn.) stands.

PubMed

Tufekcioglu, Aydin; Kucuk, Mehmet; Saglam, Bulent; Bilgili, Ertugrul; Altun, Lokman

2010-05-01

Fire is an important tool in the management of forest ecosystems. Although both prescribed and wildland fires are common in Turkey, few studies have addressed the influence of such disturbances on soil properties and root biomass dynamics. In this study, soil properties and root biomass responses to prescribed fire were investigated in 25-year-old corsican pine (Pinus nigra Arn.) stands in Kastamonu, Turkey. The stands were established by planting and were subjected to prescribed burning in July 2003. Soil respiration rates were determined every two months using soda-lime method over a two-year period. Fine (0-2 mm diameter) and small root (2-5 mm diameter) biomass were sampled approximately bimonthly using sequential coring method. Mean daily soil respiration ranged from 0.65 to 2.19 g Cm(-2) d(-1) among all sites. Soil respiration rates were significantly higher in burned sites than in controls. Soil respiration rates were correlated significantly with soil moisture and soil temperature. Fine root biomass was significantly lower in burned sites than in control sites. Mean fine root biomass values were 4940 kg ha(-1) for burned and 5450 kg ha(-1) for control sites. Soil pH was significantly higher in burned sites than in control sites in 15-35 cm soil depth. Soil organic matter content did not differ significantly between control and burned sites. Our results indicate that, depending on site conditions, fire could be used successfully as a tool in the management of forest stands in the study area.

Seasonal Fine-Root Carbohydrate and Growth Relations of Plantation Loblolly Pine After Thinning and Fertilization

Treesearch

Eric A. Kuehler; Mary Anne Sword; C. Dan Andries

1999-01-01

In 1989, two levels each of stand density and fertilization were established in an 8-year-old loblolly pine (Pinus taeda L.) plantation. In March 1995, treatments were reapplied, and root elongation and carbohydrate concentrations were monitored for 2 years. Our objective was to evaluate relationships between seasonal root growth and carbohydrate...

Optical characteristics of fine and coarse particulates at Grand Canyon, Arizona

NASA Astrophysics Data System (ADS)

Malm, William C.; Johnson, Christopher E.

The relationship between airborne particulate matter and atmospheric light extinction was examined using the multivariate techniques of principal component analysis and multiple linear regression on data gathered at the Grand Canyon, Arizona, from December 1979 to November 1981. Results showed that, on the average, fine sulfates were most strongly associated with light attenuation in the atmosphere. Other fine mass (nitrates, organics, soot and carbonaceous material) and coarse mass (primarily windblown dust) were much less associated with atmospheric extinction. Fine sulfate mass at the Grand Canyon was responsible for 63% of atmospheric light extinction while other fine mass and coarse mass were responsible for 17 and 20% of atmospheric extinction, respectively.

Genetic and environmental control of seasonal carbohydrate dynamics in trees of diverse Pinus sylvestris populations.

PubMed

Oleksyn, J.; Zytkowiak, R.; Karolewski, P.; Reich, P. B.; Tjoelker, M. G.

2000-06-01

We explored environmental and genetic factors affecting seasonal dynamics of starch and soluble nonstructural carbohydrates in needle and twig cohorts and roots of Scots pine (Pinus sylvestris L.) trees of six populations originating between 49 degrees and 60 degrees N, and grown under common garden conditions in western Poland. Trees of each population were sampled once or twice per month over a 3-year period from age 15 to 17 years. Based on similarity in starch concentration patterns in needles, two distinct groups of populations were identified; one comprised northern populations from Sweden and Russia (59-60 degrees N), and another comprised central European populations from Latvia, Poland, Germany and France (49-56 degrees N). Needle starch concentrations of northern populations started to decline in late spring and reached minimum values earlier than those of central populations. For all populations, starch accumulation in spring started when minimum air temperature permanently exceeded 0 degrees C. Starch accumulation peaked before bud break and was highest in 1-year-old needles, averaging 9-13% of dry mass. Soluble carbohydrate concentrations were lowest in spring and summer and highest in autumn and winter. There were no differences among populations in seasonal pattern of soluble carbohydrate concentrations. Averaged across all populations, needle soluble carbohydrate concentrations increased from about 4% of needle dry mass in developing current-year needles, to about 9% in 1- and 2-year-old needles. Root carbohydrate concentration exhibited a bimodal pattern with peaks in spring and autumn. Northern populations had higher concentrations of fine-root starch in spring and autumn than central populations. Late-summer carbohydrate accumulation in roots started only after depletion of starch in needles and woody shoots. We conclude that Scots pine carbohydrate dynamics depend partially on inherited properties that are probably related to phenology of root and shoot growth.

X-ray computed tomography uncovers root-root interactions: quantifying spatial relationships between interacting root systems in three dimensions.

PubMed

Paya, Alexander M; Silverberg, Jesse L; Padgett, Jennifer; Bauerle, Taryn L

2015-01-01

Research in the field of plant biology has recently demonstrated that inter- and intra-specific interactions belowground can dramatically alter root growth. Our aim was to answer questions related to the effect of inter- vs. intra-specific interactions on the growth and utilization of undisturbed space by fine roots within three dimensions (3D) using micro X-ray computed tomography. To achieve this, Populus tremuloides (quaking aspen) and Picea mariana (black spruce) seedlings were planted into containers as either solitary individuals, or inter-/intra-specific pairs, allowed to grow for 2 months, and 3D metrics developed in order to quantify their use of belowground space. In both aspen and spruce, inter-specific root interactions produced a shift in the vertical distribution of the root system volume, and deepened the average position of root tips when compared to intra-specifically growing seedlings. Inter-specific interactions also increased the minimum distance between root tips belonging to the same root system. There was no effect of belowground interactions on the radial distribution of roots, or the directionality of lateral root growth for either species. In conclusion, we found that significant differences were observed more often when comparing controls (solitary individuals) and paired seedlings (inter- or intra-specific), than when comparing inter- and intra-specifically growing seedlings. This would indicate that competition between neighboring seedlings was more responsible for shifting fine root growth in both species than was neighbor identity. However, significant inter- vs. intra-specific differences were observed, which further emphasizes the importance of biological interactions in competition studies.

Does the increased air humidity affect soil respiration and carbon stocks?

NASA Astrophysics Data System (ADS)

Kukumägi, Mai; Celi, Luisella; Said-Pullicino, Daniel; Kupper, Priit; Sõber, Jaak; Lõhmus, Krista; Kutti, Sander; Ostonen, Ivika

2013-04-01

Climate manipulation experiments at ecosystem-scale enable us to simulate, investigate and predict changes in carbon balance of forest ecosystems. Considering the predicted increase in air humidity and precipitation for northern latitudes, this work aimed at investigating the effect of increased air humidity on soil respiration, distribution of soil organic matter (SOM) among pools having different turnover times, and microbial, fine root and rhizome biomass. The study was carried out in silver birch (Betula pendula Roth.) and hybrid aspen (Populus tremula L. × P. tremuloides Michx.) stands in a Free Air Humidity Manipulation (FAHM) experimental facility containing three humidified (H; on average 7% above current ambient levels since 2008) and three control (C) plots. Soil respiration rates were measured monthly during the growing season using a closed dynamic chamber method. Density fractionation was adopted to separate SOM into two light fractions (free and aggregate-occluded particulate organic matter, fPOM and oPOM respectively), and one heavy fraction (mineral-associated organic matter, MOM). The fine root and rhizome biomass and microbial data are presented for silver birch stands only. In 2011, after 4 growing seasons of humidity manipulation soil organic carbon contents were significantly higher in C plots than H plot (13.5 and 12.5 g C kg-1, respectively), while soil respiration tended to be higher in the latter. Microbial biomass and basal respiration were 13 and 14% higher in H plots than in the C plots, respectively. Twice more fine roots of trees were estimated in H plots, while the total fine root and rhizome biomass (tree + understory) was similar in C and H plots. Fine root turnover was higher for both silver birch and understory roots in H plots. Labile SOM light fractions (fPOM and oPOM) were significantly smaller in H plots with respect to C plots (silver birch and hybrid aspen stands together), whereas no differences were observed in the contents of the more stable MOM. These results strongly suggest that, apart from the predicted increase in temperature and atmospheric carbon and nitrogen concentrations, an increase in free air humidity as a result of climate change may significantly influence the complex belowground carbon cycling by affecting biomass production, soil respiration and organic matter turnover.

CASIROZ: Root parameters and types of ectomycorrhiza of young beech plants exposed to different ozone and light regimes.

PubMed

Zeleznik, P; Hrenko, M; Then, C; Koch, N; Grebenc, T; Levanic, T; Kraigher, H

2007-03-01

Tropospheric ozone (O(3)) triggers physiological changes in leaves that affect carbon source strength leading to decreased carbon allocation below-ground, thus affecting roots and root symbionts. The effects of O(3) depend on the maturity-related physiological state of the plant, therefore adult and young forest trees might react differently. To test the applicability of young beech plants for studying the effects of O(3) on forest trees and forest stands, beech seedlings were planted in containers and exposed for two years in the Kranzberg forest FACOS experiment (Free-Air Canopy O(3) Exposure System, http://www.casiroz.de ) to enhanced ozone concentration regime (ambient [control] and double ambient concentration, not exceeding 150 ppb) under different light conditions (sun and shade). After two growing seasons the biomass of the above- and below-ground parts, beech roots (using WinRhizo programme), anatomical and molecular (ITS-RFLP and sequencing) identification of ectomycorrhizal types and nutrient concentrations were assessed. The mycorrhization of beech seedlings was very low ( CA. 5 % in shade, 10 % in sun-grown plants), no trends were observed in mycorrhization (%) due to ozone treatment. The number of Cenococcum geophilum type of ectomycorrhiza, as an indicator of stress in the forest stands, was not significantly different under different ozone treatments. It was predominantly occurring in sun-exposed plants, while its majority share was replaced by Genea hispidula in shade-grown plants. Different light regimes significantly influenced all parameters except shoot/root ratio and number of ectomycorrhizal types. In the ozone fumigated plants the number of types, number of root tips per length of 1 to 2 mm root diameter, root length density per volume of soil and concentration of Mg were significantly lower than in control plants. Trends to a decrease were found in root, shoot, leaf, and total dry weights, total number of root tips, number of vital mycorrhizal root tips, fine root (mass) density, root tip density per surface, root area index, concentration of Zn, and Ca/Al ratio. Due to the general reduction in root growth indices and nutrient cycling in ozone-fumigated plants, alterations in soil carbon pools could be predicted.

Root chemistry and soil fauna, but not soil abiotic conditions explain the effects of plant diversity on root decomposition.

PubMed

Chen, Hongmei; Oram, Natalie J; Barry, Kathryn E; Mommer, Liesje; van Ruijven, Jasper; de Kroon, Hans; Ebeling, Anne; Eisenhauer, Nico; Fischer, Christine; Gleixner, Gerd; Gessler, Arthur; González Macé, Odette; Hacker, Nina; Hildebrandt, Anke; Lange, Markus; Scherer-Lorenzen, Michael; Scheu, Stefan; Oelmann, Yvonne; Wagg, Cameron; Wilcke, Wolfgang; Wirth, Christian; Weigelt, Alexandra

2017-11-01

Plant diversity influences many ecosystem functions including root decomposition. However, due to the presence of multiple pathways via which plant diversity may affect root decomposition, our mechanistic understanding of their relationships is limited. In a grassland biodiversity experiment, we simultaneously assessed the effects of three pathways-root litter quality, soil biota, and soil abiotic conditions-on the relationships between plant diversity (in terms of species richness and the presence/absence of grasses and legumes) and root decomposition using structural equation modeling. Our final structural equation model explained 70% of the variation in root mass loss. However, different measures of plant diversity included in our model operated via different pathways to alter root mass loss. Plant species richness had a negative effect on root mass loss. This was partially due to increased Oribatida abundance, but was weakened by enhanced root potassium (K) concentration in more diverse mixtures. Equally, grass presence negatively affected root mass loss. This effect of grasses was mostly mediated via increased root lignin concentration and supported via increased Oribatida abundance and decreased root K concentration. In contrast, legume presence showed a net positive effect on root mass loss via decreased root lignin concentration and increased root magnesium concentration, both of which led to enhanced root mass loss. Overall, the different measures of plant diversity had contrasting effects on root decomposition. Furthermore, we found that root chemistry and soil biota but not root morphology or soil abiotic conditions mediated these effects of plant diversity on root decomposition.

Relationships between root respiration rate and root morphology, chemistry and anatomy in Larix gmelinii and Fraxinus mandshurica.

PubMed

Jia, Shuxia; McLaughlin, Neil B; Gu, Jiacun; Li, Xingpeng; Wang, Zhengquan

2013-06-01

Tree roots are highly heterogeneous in form and function. Previous studies revealed that fine root respiration was related to root morphology, tissue nitrogen (N) concentration and temperature, and varied with both soil depth and season. The underlying mechanisms governing the relationship between root respiration and root morphology, chemistry and anatomy along the root branch order have not been addressed. Here, we examined these relationships of the first- to fifth-order roots for near surface roots (0-10 cm) of 22-year-old larch (Larix gmelinii L.) and ash (Fraxinus mandshurica L.) plantations. Root respiration rate at 18 °C was measured by gas phase O2 electrodes across the first five branching order roots (the distal roots numbered as first order) at three times of the year. Root parameters of root diameter, specific root length (SRL), tissue N concentration, total non-structural carbohydrates (starch and soluble sugar) concentration (TNC), cortical thickness and stele diameter were also measured concurrently. With increasing root order, root diameter, TNC and the ratio of root TNC to tissue N concentration increased, while the SRL, tissue N concentration and cortical proportion decreased. Root respiration rate also monotonically decreased with increasing root order in both species. Cortical tissue (including exodermis, cortical parenchyma and endodermis) was present in the first three order roots, and cross sections of the cortex for the first-order root accounted for 68% (larch) and 86% (ash) of the total cross section of the root. Root respiration was closely related to root traits such as diameter, SRL, tissue N concentration, root TNC : tissue N ratio and stele-to-root diameter proportion among the first five orders, which explained up to 81-94% of variation in the rate of root respiration for larch and up to 83-93% for ash. These results suggest that the systematic variations of root respiration rate within tree fine root system are possibly due to the changes of tissue N concentration and anatomical structure along root branch orders in both tree species, which provide deeper understanding in the mechanism of how root traits affect root respiration in woody plants.

Effectiveness of remediation of metal-contaminated mangrove sediments (Sydney estuary, Australia).

PubMed

Birch, Gavin; Nath, Bibhash; Chaudhuri, Punarbasu

2015-04-01

Industrial activities and urbanization have had a major consequence for estuarine ecosystem health and water quality globally. Likewise, Sydney estuary has been significantly impacted by widespread, poor industrial practices in the past, and remediation of legacy contaminants have been undertaken in limited parts of this waterway. The objective of the present investigation was to determine the effectiveness of remediation of a former Pb-contaminated industrial site in Homebush Bay on Sydney estuary (Australia) through sampling of inter-tidal sediments and mangrove (Avicennia marina) tissue (fine nutritive roots, pneumatophores, and leaves). Results indicate that since remediation 6 years previously, Pb and other metals (Cu, Ni and Zn) in surficial sediment have increased to concentrations that approach pre-remediation levels and that they were considerably higher than pre-settlement levels (3-30 times), as well as at the reference site. Most metals were compartmentalized in fine nutritive roots with bio-concentration factors greater than unity, while tissues of pneumatophores and leaves contained low metal concentrations. Lead concentrations in fine nutritive root, pneumatophore, and leaf tissue of mangroves from the remediated site were similar to trees in un-remediated sites of the estuary and were substantially higher than plants at the reference site. The situation for Zn in fine nutritive root tissue was similar. The source of the metals was either surface/subsurface water from the catchment or more likely remobilized contaminated sediment from un-remediated parts of Homebush Bay. Results of this study demonstrate the problems facing management in attempting to reduce contamination in small parts of a large impacted area to concentrations below local base level.

Effects of Mesocriconema xenoplax on Vitis vinifera and Associated Mycorrhizal Fungi.

PubMed

Pinkerton, J N; Schreiner, R P; Ivors, K L; Vasconcelos, M C

2004-09-01

Previous surveys of vineyards had indicated that Mesocriconema xenoplax was present in 85% of vineyards in western Oregon, but yields were not depressed in established vines. Microplot studies were initiated in 1997 in a Willamette Valley vineyard to determine the impact of M. xenoplax on vine establishment. Plots were infested with 0.03, 0.6, and 3.0 M. xenoplax g(-1) soil and planted with self-rooted Chardonnay and Pinot Noir vines. In November 2000, four growing seasons after planting, pruning weights, fine root weights, and fruit yield of vines planted in infested soil were reduced by 58%, 75%, and 33%, respectively, relative to control vines (planted in noninfested soil). In 1998 with ca 2000 degree-day base 9 degrees C accumulation, population densities increased 32-fold and 44-fold on 1-year-old Chardonnay and Pinot Noir vines, respectively. Nematode population dynamics and pruning data suggested that the carrying capacity of vines in microplots was 5 to 8 M. xenoplax g(-1) soil. In November 2000, more than 80% of the fine root length was colonized by arbuscular mycorrhizal fungi in all treatments. The frequency of fine roots containing arbuscules (the site of nutrient transfer between plant and fungus), however, was depressed from 5% to 65% in plants infested initially with M. xenoplax as compared to controls. Competition for photosynthate within the root system is proposed as a possible mechanism by which nematodes suppressed arbuscule frequency.

Differential effects of fine root morphology on water dynamics in the root-soil interface

NASA Astrophysics Data System (ADS)

DeCarlo, K. F.; Bilheux, H.; Warren, J.

2017-12-01

Soil water uptake form plants, particularly in the rhizosphere, is a poorly understood question in the plant and soil sciences. Our study analyzed the role of belowground plant morphology on soil structural and water dynamics of 5 different plant species (juniper, grape, maize, poplar, maple), grown in sandy soils. Of these, the poplar system was extended to capture drying dynamics. Neutron radiography was used to characterize in-situ dynamics of the soil-water-plant system. A joint map of root morphology and soil moisture was created for the plant systems using digital image processing, where soil pixels were connected to associated root structures via minimum distance transforms. Results show interspecies emergent behavior - a sigmoidal relationship was observed between root diameter and bulk/rhizosphere soil water content difference. Extending this as a proxy for extent of rhizosphere development with root age, we observed a logistic growth pattern for the rhizosphere: minimal development in the early stages is superceded by rapid onset of rhizosphere formation, which then stabilizes/decays with the likely root suberization. Dynamics analysis of water content differences between the root/rhizosphere, and rhizosphere/bulk soil interface highlight the persistently higher water content in the root at all water content and root size ranges. At the rhizosphere/bulk soil interface, we observe a shift in soil water dynamics by root size: in super fine roots, we observe that water content is primarily lower in the rhizosphere under wetter conditions, which then gradually increases to a relatively higher water content under drier conditions. This shifts to a persistently higher rhizosphere water content relative to bulk soil in both wet/dry conditions with increased root size, suggesting that, by size, the finest root structures may contribute the most to total soil water uptake in plants.

Substituting root numbers for length: Improving the use of minirhizotrons to study fine root dynamics

Treesearch

Tracey L. Crocker; Ron L. Hendrick; Roger W. Ruess; Kurt S. Pregitzer; Andrew J. Burton; Michael F. Allen; Jianping Shan; Lawrence A. Morris

2003-01-01

Minirhizotrons provide a unique way to repeatedly measure the production and fate of individual root segments, while minimizing soil disturbance and the confounding of spatial-temporal variation. However, the time associated with processing videotaped minirhizotron images limits the amount of data that can be extracted in a reasonable amount of time. We found that this...

Transient nature of rhizosphere carbon elucidated by supercritical freon-22 extraction and 13C NMR analysis

Treesearch

Filipe G. Sanchez; Maurice M. Bursey

2002-01-01

The region immediately adjacent to established roots of mature trees has been termed the "reoccurring rhizosphere" and it has been hypothesized that organic matter input from fine root turnover, root exudates and sloughing may result in a build up of the soil carbon in this region. The "reoccurring rhizosphere" for first-, second- and third-order...

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...

The effects of 11 yr of CO2 enrichment on roots in a Florida scrub-oak ecosystem

Treesearch

Frank Day; Rachel Schroeder; Daniel Stover; Alisha Brown; John Butnor; John Dilustro; Bruce Hungate; Paul Dijkstra; Benjamin Duval; Troy Seiler; Bert Drake; Ross Hinkle

2013-01-01

Uncertainty surrounds belowground plant responses to rising atmospheric CO2 because roots are difficult to measure, requiring frequent monitoring as a result of fine root dynamics and long-term monitoring as a result of sensitivity to resource availability. We report belowground plant responses of a scrub-oak ecosystem in Florida exposed to 11...

Soil Carbon Budget During Establishment of Short Rotation Woody Crops

NASA Astrophysics Data System (ADS)

Coleman, M. D.

2003-12-01

Carbon budgets were monitored following forest harvest and during re-establishment of short rotation woody crops. Soil CO2 efflux was monitored using infared gas analyzer methods, fine root production was estimated with minirhizotrons, above ground litter inputs were trapped, coarse root inputs were estimated with developed allometric relationships, and soil carbon pools were measured in loblolly pine and cottonwood plantations. Our carbon budget allows evaluation of errors, as well as quantifying pools and fluxes in developing stands during non-steady-state conditions. Soil CO2 efflux was larger than the combined inputs from aboveground litter fall and root production. Fine-root production increased during stand development; however, mortality was not yet equivalent to production, showing the belowground carbon budget was not yet in equilibrium and root carbon standing crop was accruing. Belowground production was greater in cottonwood than pine, but the level of pine soil CO2 efflux was equal to or greater than that of cottonwood, indicating heterotrophic respiration was higher for pine. Comparison of unaccounted efflux with soil organic carbon changes provides verification of loss or accrual.

Root features related to plant growth and nutrient removal of 35 wetland plants.

PubMed

Lai, Wen-Ling; Wang, Shu-Qiang; Peng, Chang-Lian; Chen, Zhang-He

2011-07-01

Morphological, structural, and eco-physiological features of roots, nutrient removal, and correlation between the indices were comparatively studied for 35 emergent wetland plants in small-scale wetlands for further investigation into the hypothesis of two types of wetland plant roots (Chen et al., 2004). Significant differences in root morphological, structural, and eco-physiological features were found among the 35 species. They were divided into two types: fibrous-root plants and thick-root plants. The fibrous-root plants had most or all roots of diameter (D) ≤ 1 mm. Roots of D > 1 mm also had many fine and long lateral roots of D ≤ 1 mm. The roots of these plants were long and had a thin epidermis and a low degree of lignification. The roots of the thick-root plants were almost all thicker than 1 mm, and generally had no further fine lateral roots. The roots were short, smooth, and fleshy, and had a thick epidermis. Root porosity of the fibrous-root plants was higher than that of the thick-root plants (p = 0.001). The aerenchyma of the fibrous-root plants was composed of large cavities which were formed from many small cavities, and distributed radially between the exodermis and vascular tissues. The aerenchyma of the thick-root plants had a large number of small cavities which were distributed in the mediopellis. The fibrous-root plants had a significantly larger root biomass of D ≤ 1 mm, of 1 mm < D < 3 mm, above-ground biomass, total biomass, and longer root system, but shorter root longevity than those of the thick-root plants (p = 0.003, 0.018, 0.020, 0.032, 0.042, 0.001). The fibrous-root plants also had significantly higher radial oxygen loss (ROL), root activity, photosynthetic rate, transpiration rate, and removal rates of total nitrogen and total phosphorus than the thick-root plants (p = 0.001, 0.008, 0.010, 0.004, 0.020, 0.002). The results indicate that significantly different root morphological and structural features existed among different wetland plants, and these features had a close relationship to nutrient removal capacity. Copyright © 2011 Elsevier Ltd. All rights reserved.

SPRUCE S1 Bog Fine-root Production and Standing Crop Assessed With Minirhizotrons in the Southern and Northern Ends of the S1 Bog

DOE Data Explorer

Iversen, C. M. [Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA; Childs, J. [Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA; Norby, R. J. [Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA; Garrett, A. [Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA; Martin, A. [Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA; Spence, J. [Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA; Ontl, T. A. [Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA

2017-01-01

This data set reports fine-root peak growth and standing crop measurements from a forested, ombrotrophic bog as determined using non-destructive minirhizotron technology. Minirhizotron images were collected throughout the growing seasons of 2011 and 2012 at the southern and northern ends of the S1 bog across gradients of tree density in paired hummock and hollow microtopography. The dominant woody species in the bog, and focus of the investigation, were trees Picea mariana and Larix laricina, and ericaceous shrubs Rhododendron groenlandicum and Chamaedaphne calyculata.

Nitrogen metabolism of two contrasting poplar species during acclimation to limiting nitrogen availability

PubMed Central

Luo, Zhi-Bin

2013-01-01

To investigate N metabolism of two contrasting Populus species in acclimation to low N availability, saplings of slow-growing species (Populus popularis, Pp) and a fast-growing species (Populus alba × Populus glandulosa, Pg) were exposed to 10, 100, or 1000 μM NH4NO3. Despite greater root biomass and fine root surface area in Pp, lower net influxes of NH4 + and NO3 – at the root surface were detected in Pp compared to those in Pg, corresponding well to lower NH4 + and NO3 – content and total N concentration in Pp roots. Meanwhile, higher stable N isotope composition (δ15N) in roots and stronger responsiveness of transcriptional regulation of 18 genes involved in N metabolism were found in roots and leaves of Pp compared to those of Pg. These results indicate that the N metabolism of Pp is more sensitive to decreasing N availability than that of Pg. In both species, low N treatments decreased net influxes of NH4 + and NO3 –, root NH4 + and foliar NO3 – content, root NR activities, total N concentration in roots and leaves, and transcript levels of most ammonium (AMTs) and nitrate (NRTs) transporter genes in leaves and genes involved in N assimilation in roots and leaves. Low N availability increased fine root surface area, foliar starch concentration, δ15N in roots and leaves, and transcript abundance of several AMTs (e.g. AMT1;2) and NRTs (e.g. NRT1;2 and NRT2;4B) in roots of both species. These data indicate that poplar species slow down processes of N acquisition and assimilation in acclimation to limiting N supply. PMID:23963674

Replicated throughfall exclusion experiment in an Indonesian perhumid rainforest: wood production, litter fall and fine root growth under simulated drought.

PubMed

Moser, Gerald; Schuldt, Bernhard; Hertel, Dietrich; Horna, Viviana; Coners, Heinz; Barus, Henry; Leuschner, Christoph

2014-05-01

Climate change scenarios predict increases in the frequency and duration of ENSO-related droughts for parts of South-East Asia until the end of this century exposing the remaining rainforests to increasing drought risk. A pan-tropical review of recorded drought-related tree mortalities in more than 100 monitoring plots before, during and after drought events suggested a higher drought-vulnerability of trees in South-East Asian than in Amazonian forests. Here, we present the results of a replicated (n = 3 plots) throughfall exclusion experiment in a perhumid tropical rainforest in Sulawesi, Indonesia. In this first large-scale roof experiment outside semihumid eastern Amazonia, 60% of the throughfall was displaced during the first 8 months and 80% during the subsequent 17 months, exposing the forest to severe soil desiccation for about 17 months. In the experiment's second year, wood production decreased on average by 40% with largely different responses of the tree families (ranging from -100 to +100% change). Most sensitive were trees with high radial growth rates under moist conditions. In contrast, tree height was only a secondary factor and wood specific gravity had no influence on growth sensitivity. Fine root biomass was reduced by 35% after 25 months of soil desiccation while fine root necromass increased by 250% indicating elevated fine root mortality. Cumulative aboveground litter production was not significantly reduced in this period. The trees from this Indonesian perhumid rainforest revealed similar responses of wood and litter production and root dynamics as those in two semihumid Amazonian forests subjected to experimental drought. We conclude that trees from paleo- or neotropical forests growing in semihumid or perhumid climates may not differ systematically in their growth sensitivity and vitality under sublethal drought stress. Drought vulnerability may depend more on stem cambial activity in moist periods than on tree height or wood specific gravity. © 2013 John Wiley & Sons Ltd.

Developing a method of fabricating microchannels using plant root structure

NASA Astrophysics Data System (ADS)

Nakashima, Shota; Tokumaru, Kazuki; Tsumori, Fujio

2018-06-01

Complicated three-dimensional (3D) microchannels are expected to be applied to a lab-on-a-chip, especially an organ-on-a-chip. There are fine microchannel networks such as blood vessels in a living organ. However, it is difficult to recreate the complicated 3D microchannels of real living structures. Plant roots have a similar structure to blood vessels. They spread radially and three-dimensionally, and become thinner as they branch. In this research, we propose a method of fabricating microchannels using a live plant root as a template to mimic a blood vessel structure. We grew a plant in ceramic slurry instead of soil. The slurry consists of ceramic powder, binder and water, so it plays a similar role to soil consisting of fine particles in water. After growing the plant, the roots inside the slurry were burned and a sintered ceramic body with channel structures was obtained by heating. We used two types of slurry with different composition ratios, and compared the internal channel structures before and after sintering.

Direct in situ measurement of Carbon Allocation to Mycorrhizal Fungi in a California Mixed-Conifer Forest

NASA Astrophysics Data System (ADS)

Allen, M. F.

2011-12-01

Mycorrhizal fungi represent a large allocation of C to ecosystems, based on indirect measurements (tree girdling) and glasshouse extrapolations. However, we have no direct measures carbon (C) sink, in part because technologies for studying belowground dynamics on time scales at which roots and microbes grow and die have not existed. We initiated new sensor and observation platforms belowground to characterize and quantify belowground dynamics in a California mixed-conifer ecosystem. For the first time, we directly observed growth and mortality of mycorrhizal fungi in situ. We measured soil CO2, T and θ at 5-min intervals into the soil profile. Using our automated minirhizotron (AMR) for hyphal dynamics and the Bartz minirhizotron for longer-term and spatial variation in roots and rhizomorphs, we measured root, rhizomorph, hyphal growth, and belowground phenology up to 4x daily. These data are coupled with sensors measuring eddy flux of water and CO2, sapflow for water fluxes and C fixation activity, and photographs for leaf phenology. Because our data were collected at short intervals, we can describe integrative C exchange using the DayCent model for NPP and measured NPP of rhizomorphs, and fungal hyphae. Here, we focused on an arbuscular mycorrhiza dominated meadow and an ectomycorrhizal pine/oak forest at the James Reserve, in southern California. By daily measuring hyphal growth and mortality, we constructed life-span estimates of mycorrhizal hyphae, and from these, C allocation estimates. In the meadow, the NPP was 141g/m2/y, with a productivity of fine root+internal AM fungi of 76.5g C/m2/y, and an estimated 10% of which is AM fungal C allocation (7.7 g/m2/y). Extramatrical AM hyphal peak standing crop was 10g/m2, with a lifespan of 46 days (with active hyphae persisting for ~240 days per year days). Thus, the annual AM fungal allocation was 7.7g C/m2/y internal and 52g/m2/y external, for a net allocation of 84g C/m2/y, or 60% of the estimated NPP. In the forest, standing crop of root (300g C/m2/y), rhizomorph (2mg C/m2/y) was approximately 50% of the NPP. EM fungal hyphae mass was 18g/m2/y, with a 36day lifespan (persisting throughout the year), or 171 g C/m2/y. Individual EM root tips last most of the growing season at this site, as do individual rhizomorphs. Assuming that EM fungi represent 40% of the fine root EM NPP (of 200g C/m2/y) or 80g C/m2/y, most of the rhizomorph (in the mineral soil) mass being EM (or 2mg C) and 57% of the soil fungal NPP or 97 g C/m2/y, then the EM NPP is 177g C/m2/y, or 30% of the estimated NPP (600g C/m2/y). The next step is to incorporate dynamic events into the annual dynamics, providing a more detailed estimation of allocation, to determine fungal respiration and the proportion of root, mycorrhizal fungal, and saprotrophic, and to differentiate the proportion of residual organic C from hyphae in soils. With these data, we can now begin examining the impacts of changing temperature and moisture regimes on soil C dynamics.

Specific features of the recent accumulation of 137Cs in tree roots of forest ecosystems within the zone of radioactive contamination

NASA Astrophysics Data System (ADS)

Shcheglov, Alexey; Tsvetnova, Ol'ga; Klyashtorin, Alexey; Popova, Evgenia

2015-04-01

Despite numerous studies of the accumulation of technogenic radionuclides in the root systems, no clear regularities of this process have been established. The tendencies found in the works of Russian and foreign researchers are rather discrepant. Some authors argue that the accumulation of radionuclides in the roots is more pronounced than that in the aboveground parts of the plants (Skovorodnikova, 2005; Romantseva, 2012; Sennerby et al., 1994; Mamikhin, 2002; Fircks et al., 2002}. Other works attest to a higher accumulation of radionuclides in the aboveground pars (Juznic et al., 1990; Chibowski, 2000; Zhianski et al., 2005), which is also typical of the stable isotopes of these elements, including 133Cs (Dong Jin Kang, YongJin Seo, Tsukasa Saito et al,2012). It is also stated that the accumulation of radionuclides in the aboveground and underground parts of plants may differ in dependence on the soil-ecological conditions and other factors (Kozhakhanov et al., 2011; Grabovskyi et al., 2013). The aim of our study was to evaluate the accumulation of 137Cs in the root systems of arboreal plants in forest ecosystems within the near zone of the Chernobyl fallout on the plots with similar soil and phytocenotic features. Pine and birch stands were studied within the 30-km-wide exclusion zone of the Chernobyl Nuclear Power Station in Ukraine in 1992-1993, when the density of the radioactive contamination of the upper (0-20 cm) layer with 137Cs reached 2153.8 kBq/m2), and in Bryansk oblast of Russia in 2013-2014, when the density of contamination varied from 1458.4 kBq/m2 (pine stand) to 2578.3 kBq/m2 (birch stand). The tree layer in these ecosystems was dominated by Pinus sylvestris (L.) and Betula pendula (Roth.), respectively. Quercus robur (L.), Picea abies (L.), and Sorbus aucuparia (L.) were also present. The specific activity of 137Cs was measured in the samples from the aboveground parts of model trees and their roots differentiated by size (0-3, 3-10, 10-20, and > 20 mm), and 10-cm-deep soil horizons down to the depth of 70 cm. At the initial stage of our studies (in 1992-1993), we found that the mean weighted values of the specific activity of 137Cs in the roots was 1.5-2.0 times higher than that in the aboveground parts of the trees and also exceeded the specific activity in the adjacent soil mass. These differences increased with the depth: the activity of the roots was two times higher in the upper 10 cm and up to 100 times higher in the layer of 30-70 cm (Shcheglov, 1999; Rafferty, Kliashtorin, Kuchma, Ruehm, Shcheglov, 1996; Shcheglov, Tsvetnova, Kliashtorin, 2001). The studies performed in 2013-2014 the stage of active uptake by the roots is characterized by somewhat different regularities of the distribution of radionuclides, In conifers, including pine, the specific activity of fine roots (<3 mm) was close to the specific activity of small branches, and the specific activity of coarse roots (3-10 mm) was close to the activity of large branches. For broadleaved species, such as birch, the activity of fine roots exceeded the activity in all the aboveground organs, and the specific activity of coarse roots was close to that in small branches. More detailed studies were performed for oak and mountain ash trees. They showed that the specific activity of fine roots (<3 mm) is close to that of the small branches. The ratios of the specific activities of the coarse roots to the specific activities in different aboveground organs may differ in dependence on the species composition of tree stands. In oak and birch trees, the specific activity of coarse roots is close to the specific activity of small branches; in mountain ash, it is closer to the specific activity of small branches.

Uptake of Cadmium by Flue-Cured Tobacco Plants: Exploring Bioavailability

NASA Astrophysics Data System (ADS)

Holzer, I.; Robarge, W. P.; Vann, M. C.

2015-12-01

Scientific understanding of cadmium (Cd) cycling in North Carolina tobacco plants and soils has lagged, even as production of flue-cured tobacco remains an important part of the NC economy ($903 million in 2014). Cd is considered a tobacco contaminant. When tobacco is burned, Cd can exist as a fine aerosol and subsequent inhalation is linked to cancer. Tobacco root exudates enhance Cd uptake, even though the Cd concentration in NC soils is <0.1 mg/kg. Quantifying Cd concentrations in tobacco plants is crucial to understanding Cd bioavailability and implementing soil remediation efforts. The objective of this study was to develop a Cd mass balance for flue-cured tobacco grown under field conditions in NC. Whole plant samples were collected at transplanting and every 2 weeks thereafter until harvest. Individual plants were segregated into root, stalk and individual leaves (n = 15 whole plants/sampling date; composite samples were taken early in the growing season). After recording dry mass, samples were analyzed using ion-coupled plasma optical emission spectrometry or ion-coupled plasma mass spectrometry. Lower leaves contained the highest Cd concentrations ( 7-10 mg/kg). Leaves occupying the upper 50% of the plant had Cd concentrations of 2 mg/kg. Uptake rate was greatest from day 27 to 66 ( 21.5 μg Cd/day). Selective Cd uptake appears evident between day 27 and 43, but overall the relative rate of Cd uptake was similar to other trace metals and micronutrients. Cd distribution within the plants mirrored the distribution of calcium, a macronutrient. Of the 8 mg of soil extractable Cd (0.075 mg/kg) in the rooting zone, 15.0% (1203 μg) is removed by uptake. Of this 15%, 64.2% (772.2 μg) is exported at harvest, and 35.8% (430.8 μg; lower leaves, roots, stalks) is returned to the soil. This study must be replicated to account for seasonal and soil variations. These results do inform selection of tobacco strains that limit uptake of trace metals, particularly Cd.

Liquid Chromatography Mass Spectrometry Analysis and Cytotoxicity of Asparagus adscendens Roots against Human Cancer Cell Lines.

PubMed

Khan, Kashif Maqbool; Nahar, Lutfun; Mannan, Abdul; Arfan, Muhammad; Khan, Ghazanfar Ali; Al-Groshi, Afaf; Evans, Andrew; Dempster, Nicola M; Ismail, Fyaz M D; Sarker, Satyajit D

2018-01-01

Asparagus adscendens Roxb. (Asparagaceae), is native to the Himalayas. This plant has been used in the prevention and effective treatment of various forms of cancers. This paper reports, for the first time, on the cytotoxicity of the methanol (MeOH) extract of the roots of A. adscendens and its solid-phase extraction (SPE) fractions against four human carcinoma cell lines and LC-ESI-QTOF-MS analysis of the SPE fractions. Finely powdered roots of A. adscendens were macerated in methanol and extracted through SPE using gradient solvent system (water: methanol) proceeded for analysis on LC-ESI-QTOF-MS and cytotoxicity against four human carcinoma cell lines: breast (MCF7), liver (HEPG2), lung (A549), and urinary bladder (EJ138), using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide assay. The MeOH extract and four SPE fractions exhibited cytotoxicity against all cell lines with the IC 50 values ranging from 6 to 79 μg/mL. As observed in other Asparagus species, the presence of saponins and sapogenins in the SPE fractions was evident in the liquid chromatography-mass spectrometry data. It is reasonable to assume that the cytotoxicity of the MeOH extract of the roots of A. adscendens and its SPE fractions, at least partly, due to the presence of saponins and their aglycones. This suggests that A. adscendens could be exploited as a potential source of cytotoxic compounds with putative anticancer potential. The MeOH extract and all solid-phase extraction (SPE) fractions exhibited various levels of cytotoxicity against all cell lines with the IC 50 values ranging from 6 to 79 μg/mLThe presence of saponins and sapogenins in the SPE fractions was evident in the Liquid chromatography-mass spectrometry dataDue to the presence of saponins and their aglycones, suggest that A. adscendens could be exploited as a potential source of cytotoxic compounds with putative anticancer potential. Abbreviation used: SPE: Solid-phase extraction, MCF7: Breast cancer cell line, HEPG2: Liver cancer cell line, A549: Lung liver cancer cell line, EJ138: Urinary bladder cancer cell line, MTT: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide, LC-MS: Liquid chromatography-mass spectrometry.

Competition for nitrogen between Fagus sylvatica and Acer pseudoplatanus seedlings depends on soil nitrogen availability.

PubMed

Li, Xiuyuan; Rennenberg, Heinz; Simon, Judy

2015-01-01

Competition for nitrogen (N), particularly in resource-limited habitats, might be avoided by different N acquisition strategies of plants. In our study, we investigated whether slow-growing European beech and fast-growing sycamore maple seedlings avoid competition for growth-limiting N by different N uptake patterns and the potential alteration by soil N availability in a microcosm experiment. We quantified growth and biomass indices, (15)N uptake capacity and N pools in the fine roots. Overall, growth indices, N acquisition and N pools in the fine roots were influenced by species-specific competition depending on soil N availability. With inter-specific competition, growth of sycamore maple reduced regardless of soil N supply, whereas beech only showed reduced growth when N was limited. Both species responded to inter-specific competition by alteration of N pools in the fine roots; however, sycamore maple showed a stronger response compared to beech for almost all N pools in roots, except for structural N at low soil N availability. Beech generally preferred organic N acquisition while sycamore maple took up more inorganic N. Furthermore, with inter-specific competition, beech had an enhanced organic N uptake capacity, while in sycamore maple inorganic N uptake capacity was impaired by the presence of beech. Although sycamore maple could tolerate the suboptimal conditions at the cost of reduced growth, our study indicates its reduced competitive ability for N compared to beech.

Use of Stored Carbon Reserves in Growth of Temperate Tree Roots and Leaf Buds: Analyses Using Radiocarbon Measurements and Modeling

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

Gaudinski, Julia B.; Torn, Margaret S.; Riley, W. J.

2009-01-01

Characterizing the use of C reserves in trees is important for understanding stress responses, impacts of asynchrony between photosynthesis and growth demand, and isotopic exchanges in plant dynamic studies. Using an inadvertent, whole ecosystem radiocarbon (14C) exposure in a temperate deciduous oak forest and numerical modeling, we calculated that the mean age of stored C used to grow leaf buds and new fine root tissue is 0.5-1.0 y. The mean age of stored C used to grow new roots was about 0.7 y across a range of realistic values of 14C inputs to the system. The amount of stored Cmore » used on an annual basis to grow fine roots was between 15 and 55% of total root growth, with the range defined by the assumed 14C input profile. We estimate the annually-averaged mean age of C in new root tissues is 1-5 months. Therefore, accounting for storage C use in isotope root models may be unnecessary in all but the fastest cycling root populations (i.e., mean age <1 y). Consistent with the whole ecosystem labeling results, we found, using "bomb-14C," that the mean C age of new root tissues in three additional forest sites (one deciduous, two coniferous) was less than 2 years. We conclude that in many ecosystem types, growth from stored C is insufficient to impact bomb-14C based estimates of long root lifetimes.« less

An evaluation of inexpensive methods for root image acquisition when using rhizotrons.

PubMed

Mohamed, Awaz; Monnier, Yogan; Mao, Zhun; Lobet, Guillaume; Maeght, Jean-Luc; Ramel, Merlin; Stokes, Alexia

2017-01-01

Belowground processes play an essential role in ecosystem nutrient cycling and the global carbon budget cycle. Quantifying fine root growth is crucial to the understanding of ecosystem structure and function and in predicting how ecosystems respond to climate variability. A better understanding of root system growth is necessary, but choosing the best method of observation is complex, especially in the natural soil environment. Here, we compare five methods of root image acquisition using inexpensive technology that is currently available on the market: flatbed scanner, handheld scanner, manual tracing, a smartphone application scanner and a time-lapse camera. Using the five methods, root elongation rate (RER) was measured for three months, on roots of hybrid walnut ( Juglans nigra  ×  Juglans regia L.) in rhizotrons installed in agroforests. When all methods were compared together, there were no significant differences in relative cumulative root length. However, the time-lapse camera and the manual tracing method significantly overestimated the relative mean diameter of roots compared to the three scanning methods. The smartphone scanning application was found to perform best overall when considering image quality and ease of use in the field. The automatic time-lapse camera was useful for measuring RER over several months without any human intervention. Our results show that inexpensive scanning and automated methods provide correct measurements of root elongation and length (but not diameter when using the time-lapse camera). These methods are capable of detecting fine roots to a diameter of 0.1 mm and can therefore be selected by the user depending on the data required.

Elevated root retention of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in coniferous trees.

PubMed

Schoenmuth, Bernd; Mueller, Jakob O; Scharnhorst, Tanja; Schenke, Detlef; Büttner, Carmen; Pestemer, Wilfried

2014-03-01

For decades, the explosive RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) has been used for military and industrial applications. Residues of RDX pollute soils in large areas globally and the persistence and high soil mobility of these residues can lead to leaching into groundwater. Dendroremediation, i.e. the long-term use of trees to clean up polluted soils, is gaining acceptance as a green and sustainable strategy. Although the coniferous tree species Norway spruce and Scots pine cover large areas of military land in Central Europe, the potential of any coniferous tree for dendroremediation of RDX is still unknown. In this study, uptake experiments with a (14)C-labelled RDX solution (30 mg L(-1)) revealed that RDX was predominantly retained in the roots of 6-year-old coniferous trees. Only 23 % (pine) to 34 % (spruce) of RDX equivalents (RDXeq) taken up by the roots were translocated to aboveground tree compartments. This finding contrasts with the high aerial accumulation of RDXeq (up to 95 %) in the mass balances of all other plant species. Belowground retention of RDXeq is relatively stable in fine root fractions, since water leaching from tissue homogenates was less than 5 %. However, remobilisation from milled coarse roots and tree stubs reached up to 53 %. Leaching from homogenised aerial tree material was found to reach 64 % for needles, 58 % for stems and twigs and 40 % for spring sprouts. Leaching of RDX by precipitation increases the risk for undesired re-entry into the soil. However, it also opens the opportunity for microbial mineralisation in the litter layer or in the rhizosphere of coniferous forests and offers a chance for repeated uptake of RDX by the tree roots.

CHOICE OF INDICATOR DETERMINES THE SIGNIFICANCE AND RISK OBTAINED FROM THE STATISTICAL ASSOCIATION BETWEN FINE PARTICULATE MATTER MASS AND CARDIOVASCULAR MORTALITY

EPA Science Inventory

Minor changes in the indicator used to measure fine PM, which cause only modest changes in Mass concentrations, can lead to dramatic changes in the statistical relationship of fine PM mass with cardiovascular mortality. An epidemiologic study in Phoenix (Mar et al., 2000), augme...

Response of “Alamo” switchgrass tissue chemistry and biomass to nitrogen fertilization in West Tennessee, USA

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

Garten, Charles T.; Brice, Deanne J.; Castro, Hector F.

2011-01-01

Switchgrass (Panicum virgatum) is a perennial, warm-season grass that has been identified as a potential biofuel feedstock over a large part of North America. We examined above- and belowground responses to nitrogen fertilization in “Alamo” switchgrass grown in West Tennessee, USA. The fertilizer study included a spring and fall sampling of 5-year old switchgrass grown under annual applications of 0, 67, and 202 kg N ha -1 (as ammonium nitrate). Fertilization changed switchgrass biomass allocation as indicated by root:shoot ratios. End-of-growing season root:shoot ratios (mean ± SE) declined significantly (P ≤ 0.05) at the highest fertilizer nitrogen treatment (2.16 ±more » 0.08, 2.02 ± 0.18, and 0.88 ± 0.14, respectively, at 0, 67, and 202 kg N ha -1). Fertilization also significantly increased above- and belowground nitrogen concentrations and decreased plant C:N ratios. Data are presented for coarse live roots, fine live roots, coarse dead roots, fine dead roots, and rhizomes. At the end of the growing season, there was more carbon and nitrogen stored in belowground biomass than aboveground biomass. Finally, fertilization impacted switchgrass tissue chemistry and biomass allocation in ways that potentially impact soil carbon cycle processes and soil carbon storage.« less

Warming and elevated CO 2 alter the suberin chemistry in roots of photosynthetically divergent grass species

DOE PAGES

Suseela, Vidya; Tharayil, Nishanth; Pendall, Elise; ...

2017-09-01

A majority of soil carbon (C) is either directly or indirectly derived from fine roots, yet roots remain the least understood component of the terrestrial carbon cycle. The decomposability of fine roots and their potential to contribute to soil C is partly regulated by their tissue chemical composition. Roots rely heavily on heteropolymers such as suberins, lignins and tannins to adapt to various environmental pressures and to maximize their resource uptake functions. Since the chemical construction of roots is partly shaped by their immediate biotic/abiotic soil environments, global changes that perturb soil resource availability and plant growth could potentially altermore » root chemistry, and hence the decomposability of roots. However, the effect of global change on the quantity and composition of root heteropolymers are seldom investigated. We examined the effects of elevated CO 2 and warming on the quantity and composition of suberin in roots of Bouteloua gracilis (C4) and Hesperostipa comata (C3) grass species at the Prairie Heating and CO 2 Enrichment (PHACE) experiment at Wyoming, USA. Roots of B. gracilis exposed to elevated CO 2 and warming had higher abundances of suberin and lignin than those exposed to ambient climate treatments. In addition to changes in their abundance, roots exposed to warming and elevated CO 2 had higher ω-hydroxy acids compared to plants grown under ambient conditions. The suberin content and composition in roots of H. comata was less responsive to climate treatments. In H. comata, α,ω-dioic acids increased with the main effect of elevated CO 2, whereas the total quantity of suberin exhibited an increasing trend with the main effect of warming and elevated CO 2. The increase in suberin content and altered composition could lower root decomposition rates with implications for root-derived soil carbon under global change. Our study also suggests that the climate change induced alterations in species composition will further mediate potential suberin contributions to soil carbon pools.« less

Warming and elevated CO 2 alter the suberin chemistry in roots of photosynthetically divergent grass species

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

Suseela, Vidya; Tharayil, Nishanth; Pendall, Elise

A majority of soil carbon (C) is either directly or indirectly derived from fine roots, yet roots remain the least understood component of the terrestrial carbon cycle. The decomposability of fine roots and their potential to contribute to soil C is partly regulated by their tissue chemical composition. Roots rely heavily on heteropolymers such as suberins, lignins and tannins to adapt to various environmental pressures and to maximize their resource uptake functions. Since the chemical construction of roots is partly shaped by their immediate biotic/abiotic soil environments, global changes that perturb soil resource availability and plant growth could potentially altermore » root chemistry, and hence the decomposability of roots. However, the effect of global change on the quantity and composition of root heteropolymers are seldom investigated. We examined the effects of elevated CO 2 and warming on the quantity and composition of suberin in roots of Bouteloua gracilis (C4) and Hesperostipa comata (C3) grass species at the Prairie Heating and CO 2 Enrichment (PHACE) experiment at Wyoming, USA. Roots of B. gracilis exposed to elevated CO 2 and warming had higher abundances of suberin and lignin than those exposed to ambient climate treatments. In addition to changes in their abundance, roots exposed to warming and elevated CO 2 had higher ω-hydroxy acids compared to plants grown under ambient conditions. The suberin content and composition in roots of H. comata was less responsive to climate treatments. In H. comata, α,ω-dioic acids increased with the main effect of elevated CO 2, whereas the total quantity of suberin exhibited an increasing trend with the main effect of warming and elevated CO 2. The increase in suberin content and altered composition could lower root decomposition rates with implications for root-derived soil carbon under global change. Our study also suggests that the climate change induced alterations in species composition will further mediate potential suberin contributions to soil carbon pools.« less

INDEPENDENT AND CONTRASTING EFFECTS OF ELEVATED CO2 AND N-FERTILIZATION ROOT ARCHITECTURE

EPA Science Inventory

The effects of elevated CO2 and N fertilization on architecture of Pinus ponderosa fine roots and their associated mycorrhizal symbionts were measured over a 4-year period. The study was conducted in open-top field-exposure chambers located near Placerville, CA. A replicated (thr...

Mycorrhizae

Treesearch

Martin Jurgensen; Dana Richter; Carl C. Trettin; Mary Davis

2000-01-01

Mycorrhizae, a mutual partnership between certain soil fungi and fine root tips, contribute to tree growth and vigor by increasing both water and nutrient uptake, especially nitrogen (N) and phosphorus (P). The fungal hyphae increase root surface contact with the soil, while the fungi are supplied with a reliable source of carbon (Allen 1991, George and Marschner 1995...

ROLE OF CARBOHYDRATE SUPPLY IN WHITE AND BROWN ROOT RESPIRATION OF PONDEROSA PINE

EPA Science Inventory

Respiratory responses of fine ponderosa pine (Pinus ponderosa Laws) roots of differing morphology were measured to evaluate response to excision and to changes in the shoot light environment. Ponderosa pine seedlings were subject to either a 15:9 h light/dark environment over 24...

Blackhole formula and example relativity

NASA Astrophysics Data System (ADS)

Shin, Philip

Black hole formula 1) Second dimension (x,y) f(x)=y Energy E=m*c2 2) Third dimension (x,y,z) really x=y=z Black hole formula Root(c2)=c=Root(E/m) As mass go the velocity of light, mass become black hole so there are energy as multiply by mass. Example relativity When E=m*c2 1) Root(c2)=c=Root(E/m) 2) 3*c*Root(c2)=3*c*Root(E/m)=3*c2 From 1) to 2) as an example, As velocity is faster, mass increased. It means when velocity is increased, sec(time) is slower, and m(distance) is increased. The number is good to study physics.

Nitrogen regulation of transpiration controls mass-flow acquisition of nutrients.

PubMed

Matimati, Ignatious; Verboom, G Anthony; Cramer, Michael D

2014-01-01

Transpiration may enhance mass-flow of nutrients to roots, especially in low-nutrient soils or where the root system is not extensively developed. Previous work suggested that nitrogen (N) may regulate mass-flow of nutrients. Experiments were conducted to determine whether N regulates water fluxes, and whether this regulation has a functional role in controlling the mass-flow of nutrients to roots. Phaseolus vulgaris were grown in troughs designed to create an N availability gradient by restricting roots from intercepting a slow-release N source, which was placed at one of six distances behind a 25 μm mesh from which nutrients could move by diffusion or mass-flow (termed 'mass-flow' treatment). Control plants had the N source supplied directly to their root zone so that N was available through interception, mass-flow, and diffusion (termed 'interception' treatment). 'Mass-flow' plants closest to the N source exhibited 2.9-fold higher transpiration (E), 2.6-fold higher stomatal conductance (gs), 1.2-fold higher intercellular [CO2] (Ci), and 3.4-fold lower water use efficiency than 'interception' plants, despite comparable values of photosynthetic rate (A). E, gs, and Ci first increased and then decreased with increasing distance from the N source to values even lower than those of 'interception' plants. 'Mass-flow' plants accumulated phosphorus and potassium, and had maximum concentrations at 10mm from the N source. Overall, N availability regulated transpiration-driven mass-flow of nutrients from substrate zones that were inaccessible to roots. Thus when water is available, mass-flow may partially substitute for root density in providing access to nutrients without incurring the costs of root extension, although the efficacy of mass-flow also depends on soil nutrient retention and hydraulic properties.

Nitrogen regulation of transpiration controls mass-flow acquisition of nutrients

PubMed Central

Matimati, Ignatious

2014-01-01

Transpiration may enhance mass-flow of nutrients to roots, especially in low-nutrient soils or where the root system is not extensively developed. Previous work suggested that nitrogen (N) may regulate mass-flow of nutrients. Experiments were conducted to determine whether N regulates water fluxes, and whether this regulation has a functional role in controlling the mass-flow of nutrients to roots. Phaseolus vulgaris were grown in troughs designed to create an N availability gradient by restricting roots from intercepting a slow-release N source, which was placed at one of six distances behind a 25 μm mesh from which nutrients could move by diffusion or mass-flow (termed ‘mass-flow’ treatment). Control plants had the N source supplied directly to their root zone so that N was available through interception, mass-flow, and diffusion (termed ‘interception’ treatment). ‘Mass-flow’ plants closest to the N source exhibited 2.9-fold higher transpiration (E), 2.6-fold higher stomatal conductance (g s), 1.2-fold higher intercellular [CO2] (C i), and 3.4-fold lower water use efficiency than ‘interception’ plants, despite comparable values of photosynthetic rate (A). E, g s, and C i first increased and then decreased with increasing distance from the N source to values even lower than those of ‘interception’ plants. ‘Mass-flow’ plants accumulated phosphorus and potassium, and had maximum concentrations at 10mm from the N source. Overall, N availability regulated transpiration-driven mass-flow of nutrients from substrate zones that were inaccessible to roots. Thus when water is available, mass-flow may partially substitute for root density in providing access to nutrients without incurring the costs of root extension, although the efficacy of mass-flow also depends on soil nutrient retention and hydraulic properties. PMID:24231035

[Effects of ridge-cultivation and plastic film mulching on root distribution and yield of spring maize in hilly area of central Sichuan basin, China.

PubMed

Zha, Li; Xie, Meng Lin; Zhu, Min; Dou, Pan; Cheng, Qiu Bo; Wang, Xing Long; Yuan, Ji Chao; Kong, Fan Lei

2016-03-01

A field experiment was conducted to study the effects of planting pattern (ridge culture, flatten culture, furrow culture) and film mulching on the distribution of spring maize root system and their influence on the yield of spring maize in the hilly area of central Sichuan basin. The results showed that ridge and film mulching had great influence on root morphology and root distribution of maize. The root length, root surface area and root volume of film mulching was 42.3%, 50.0%, 57.4% higher than those of no film mulching at jointing stage. The film mulching significantly increased the dry mass of root in vertical and horizontal distribution, and increased the root allocation ratio in deeper soil layer (20-40 cm) and the allocation ratio of wide row (0-20 cm) in horizontal direction. The effects of planting pattern on root growth and root distribution differed by film mulching. With film mulching, the ridge culture significantly increased the root dry mass in each soil layer and enlarged the distribution percentage of wide row (20-40 cm) in horizontal direction, as well as the dry mass of root in horizontal distribution and the root allocation ratio of wide row. The root mass under film mulching was in the order of ridge culture>flatten culture>furrow culture. Without film mulching, the furrow culture significantly increased root dry mass of narrow row (0-40 cm), and the root mass under no film mulching was in the order of furrow culture > ridge culture >flatten culture. As for the spike characteristics and maize yield, the filming mulching mea-sures reduced the corn bald length while increased the spike length, grain number, 1000-grain mass and yield. The yield under film mulching was in the order of ridge culture>flatten culture> furrow culture, while it was furrow culture > flatten culture > ridge culture under no film mulching. The reason for yield increase under ridge culture with film mulching was that it increased root weight especially in deep soil, and promoted the root allocation ratio in deeper soil and wide row (20-40 cm) in horizontal direction. The ridge-furrow culture without film mulching was helpful to root growth and increased the maize yield.

Advancing the use of minirhizotrons in wetlands

Treesearch

C. M. Iversen; M. T. Murphy; M. F. Allen; J. Childs; D. M. Eissenstat; E.A. Lilleskov; T. M. Sarjala; V. L. Sloan; P. F. Sullivan

2012-01-01

Background. Wetlands store a substantial amount of carbon (C) in deep soil organic matter deposits, and play an important role in global fluxes of carbon dioxide and methane. Fine roots (i.e., ephemeral roots that are active in water and nutrient uptake) are recognized as important components of biogeochemical cycles in nutrient-limited wetland ecosystems. However,...

Stunting of southern pine seedlings by a needle nematode (Longidorus sp.)

Treesearch

M.M. Cram; S.W. Fraedrich; J. Fields

2003-01-01

An undescribed needle nematode (Longidorus sp.) was consistently associated with stunted loblolly pine seedlings at the Flint River Nursery in south Georgia. Seedlings in affected areas had root systems that were greatly reduced in size, and lacked lateral and fine roots. In a growth chamber experiment, the needle nematode significantly reduced the...

Competition for nitrogen between Fagus sylvatica and Acer pseudoplatanus seedlings depends on soil nitrogen availability

PubMed Central

Li, Xiuyuan; Rennenberg, Heinz; Simon, Judy

2015-01-01

Competition for nitrogen (N), particularly in resource-limited habitats, might be avoided by different N acquisition strategies of plants. In our study, we investigated whether slow-growing European beech and fast-growing sycamore maple seedlings avoid competition for growth-limiting N by different N uptake patterns and the potential alteration by soil N availability in a microcosm experiment. We quantified growth and biomass indices, 15N uptake capacity and N pools in the fine roots. Overall, growth indices, N acquisition and N pools in the fine roots were influenced by species-specific competition depending on soil N availability. With inter-specific competition, growth of sycamore maple reduced regardless of soil N supply, whereas beech only showed reduced growth when N was limited. Both species responded to inter-specific competition by alteration of N pools in the fine roots; however, sycamore maple showed a stronger response compared to beech for almost all N pools in roots, except for structural N at low soil N availability. Beech generally preferred organic N acquisition while sycamore maple took up more inorganic N. Furthermore, with inter-specific competition, beech had an enhanced organic N uptake capacity, while in sycamore maple inorganic N uptake capacity was impaired by the presence of beech. Although sycamore maple could tolerate the suboptimal conditions at the cost of reduced growth, our study indicates its reduced competitive ability for N compared to beech. PMID:25983738

Above and below ground carbohydrate allocation differs between ash (Fraxinus excelsior L.) and beech (Fagus sylvatica L.)

PubMed Central

Thoms, Ronny; Köhler, Michael; Gessler, Arthur

2017-01-01

We investigated soluble carbohydrate transport in trees that differed in their phloem loading strategies in order to better understand the transport of photosynthetic products into the roots and the rhizosphere as this knowledge is needed to better understand the respiratory processes in the rhizosphere. We compared beech, which is suggested to use mainly passive loading of transport sugars along a concentration gradient into the phloem, with ash that uses active loading and polymer trapping of raffinose family oligosaccharides (RFOs). We pulse-labeled 20 four-year old European beech and 20 four-year old ash trees with 13CO2 and tracked the fate of the label within different plant compartments. We extracted soluble carbohydrates from leaves, bark of stems and branches, and fine roots, measured their amount and isotopic content and calculated their turnover times. In beech one part of the sucrose was rapidly transported into sink tissues without major exchange with storage pools whereas another part of sucrose was strongly exchanged with unlabeled possibly stored sucrose. In contrast the storage and allocation patterns in ash depended on the identity of the transported sugars. RFO were the most important transport sugars that had highest turnover in all shoot compartments. However, the turnover of RFOs in the roots was uncoupled from the shoot. The only significant relation between sugars in the stem base and in the roots of ash was found for the amount (r2 = 0.50; p = 0.001) and isotopic content (r2 = 0.47; p = 0.01) of sucrose. The negative relation of the amounts suggested an active transport of sucrose into the roots of ash. Sucrose concentration in the root also best explained the concentration of RFOs in the roots suggesting that RFO in the roots of ash may be resynthesized from sucrose. Our results interestingly suggest that in both tree species only sucrose directly entered the fine root system and that in ash RFOs are transported indirectly into the fine roots only. The direct transport of sucrose might be passive in beech but active in ash (sustained active up- and unloading to co-cells), which would correspond to the phloem loading strategies. Our results give first hints that the transport of carbohydrates between shoot and root is not necessarily continuous and involves passive (beech) and active (ash) transport processes, which may be controlled by the phloem unloading. PMID:28934229

Belowground Processes in Nitrogen Fertilized Cottonwood and Loblolly Pine Plantations

Treesearch

Kye-Han Lee; Shibu Jose

2004-01-01

We measured soil respiration, fine root biomass production, and microbial biomass along a fertilization gradient (0, 56, 112, and 224 kg N ha-1 per year) in 7-year-old cottonwood and loblolly pine plantations, established on a well-drained, Redbay sandy loam (a fine-loamy, siliceous, thermic Rhodic Paleudlt), in northwest Florida. Annual soil...

Annual fire and mowing alter biomass, depth distribution, and C and N content of roots in soil in tallgrass prairie

Treesearch

D.J. Kitchen; J.M. Blair; M.A. Callaham

2009-01-01

Management practices, such as fire andmowing, can affect the distribution and quality of roots and soil C and N in grasslands. We examined long-term (13 years) effects of annual fire and mowing on fine (<2 mm) roots and soil C and N content in a native tallgrass prairie at Konza Prairie Biological Station in northeastern Kansas, USA. Using 90 cm deep soil cores...

First measurements of ambient aerosol over an ecologically sensitive zone in Central India: Relationships between PM2.5 mass, its optical properties, and meteorology.

PubMed

Sunder Raman, Ramya; Kumar, Samresh

2016-04-15

PM2.5 mass and its optical properties were measured over an ecologically sensitive zone in Central India between January and December, 2012. Meteorological parameters including temperature, relative humidity, wind speed, wind direction, and barometric pressure were also monitored. During the study period, the PM2.5 (fine PM) concentration ranged between 3.2μgm(-3) and 193.9μgm(-3) with a median concentration of 31.4μgm(-3). The attenuation coefficients, βATN at 370nm, 550nm, and 880nm had median values of 104.5Mm(-1), 79.2Mm(-1), and 59.8Mm(-1), respectively. Further, the dry scattering coefficient, βSCAT at 550nm had a median value of 17.1Mm(-1) while the absorption coefficient βABS at 550nm had a median value of 61.2Mm(-1). The relationship between fine PM mass and attenuation coefficients showed pronounced seasonality. Scattering, absorption, and attenuation coefficient at different wavelengths were all well correlated with fine PM mass only during the post-monsoon season (October, November, and December). The highest correlation (r(2)=0.81) was between fine PM mass and βSCAT at 550nm during post-monsoon season. During this season, the mass scattering efficiency (σSCAT) was 1.44m(2)g(-1). Thus, monitoring optical properties all year round, as a surrogate for fine PM mass was found unsuitable for the study location. In order to assess the relationships between fine PM mass and its optical properties and meteorological parameters, multiple linear regression (MLR) models were fitted for each season, with fine PM mass as the dependent variable. Such a model fitted for the post-monsoon season explained over 88% of the variability in fine PM mass. However, the MLR models were able to explain only 31 and 32% of the variability in fine PM during pre-monsoon (March, April, and May) and monsoon (June, July, August, and September) seasons, respectively. During the winter (January and February) season, the MLR model explained 54% of the PM2.5 variability. Copyright © 2016 Elsevier B.V. All rights reserved.

Stronger influence of litter quality on decomposition rates than microbial home field advantage in novel subtropical dry forests

NASA Astrophysics Data System (ADS)

Marin-Spiotta, E.; Atkinson, E. E.

2015-12-01

Litter decomposition is one of the most studied ecosystem processes, given its role in carbon cycling and nutrient availability, yet our knowledge of how decomposition is influenced by novel species assemblages in tropical forests emerging on post-agricultural landscapes is limited. This is especially true in tropical dry forests, which are some of the most fragmented forests worldwide due to human pressures and sensitive to changes in rainfall and fire regimes. Here we tested for the effects of litter quality, site conditions, and microbial "home-field advantage" on decomposition rates in subtropical dry forests in St. Croix, U.S. Virgin Islands. We conducted a 22-month in situ and reciprocal transplant field decomposition experiment of aboveground litter and fine roots in 10-year old sites dominated by an early successional N-fixing tree and 40-year old mixed-species secondary forests. Total annual litterfall mass did not differ between the two forest types, but monthly amounts did, with more litter accumulating in the 40-year old secondary forests during the dry season and in the 10-year old secondary forests during the wet season. Litter chemistry differed between the two forest types and showed divergent patterns over the two-year field incubation. To test for the effects of litter quality on decomposition rates, we compared mass loss rates for aboveground and root litter from each forest decomposed in situ and transplanted to the other forest type. Litter in the 10-year old forests decomposed faster in situ (k= 1.07 ± 0.04) than when it was transplanted (k=0.86 ± 0.04). Litter from the 40-year old forests showed the opposite pattern. In situ root decomposition in both forests occurred at the same rate compared to roots that were transplanted there from the other forest type, suggesting that site conditions were equally important as litter quality. Our results were not consistent with a microbial home-field advantage for litter and root decomposition, that is, microbes were not more efficient at decomposing their own native litter, regardless of chemistry. Rather, decomposition patterns may be largely controlled by litter quality (and the combined effects of litter quality and site conditions specifically for roots) in contrast to the decomposer community in these subtropical dry forests.

Belowground Plant Dynamics Across an Arctic Landscape

NASA Astrophysics Data System (ADS)

Salmon, V. G.; Iversen, C. M.; Breen, A. L.; Thornton, P. E.; Wullschleger, S.

2017-12-01

High-latitude ecosystems are made up of a mosaic of different plant communities, all of which are exposed to warming at a rate double that observed in ecosystems at lower latitudes. Arctic regions are an important component of global Earth system models due to the large amounts of soil carbon (C) currently stored in permafrost as well their potential for increased plant C sequestration under warmer conditions. Losses of C from thawing and decomposing permafrost may be offset by increased plant productivity, but plant allocation to belowground structures and acquisition of limiting nutrients remain key sources of uncertainty in these ecosystems. The relationship between belowground plant traits and environmental conditions is not well understood, nor are tradeoffs between above- and belowground plant traits. To address these knowledge gaps, we sampled above- and belowground plant tissues along the Kougarok Hillslope on the Seward Peninsula, Alaska. The vegetation communities sampled included Alder shrubland, willow birch tundra, tussock tundra, dwarf shrub lichen tundra, and non-acidic mountain complex. Within each plant community, aboveground biomass was quantified and specific leaf area, leaf chemistry (%C, %N, %P and δ15N), and wood density were measured. Belowground fine-root biomass and rooting depth distribution were also determined at the community level. Fine roots from shrubs and graminoids were separated so that specific root area, diameter, and chemistry (%C, %N, %P and δ15N) could be assessed for these contrasting plant functional types. Initial findings indicate fine root biomass pools across the widely varying plant communities are constrained by soil depth, regardless of whether the rooting zone is restricted by permafrost or rock. The presence of Alnus viridis subspp. fruticosa, a deciduous shrub that facilitates nitrogen (N) fixation within its root nodules by Frankia bacteria, in Alder shrubland and willow birch tundra communities was associated with increased soil N availability and altered chemistry in neighboring plants. This research aims to identify sources of variation in belowground plant traits and provide insight into how incorporating belowground plant dynamics into Earth system models may improve our ability to predict the fate of these rapidly warming ecosystems.

Soil Aeration deficiencies in urban sites

NASA Astrophysics Data System (ADS)

Weltecke, Katharina; Gaertig, Thorsten

2010-05-01

Soil aeration deficiencies in urban sites Katharina Weltecke and Thorsten Gaertig On urban tree sites reduction of soil aeration by compaction or sealing is an important but frequently underestimated factor for tree growth. Up to 50% of the CO2 assimilated during the vegetation period is respired in the root space (Qi et al. 1994). An adequate supply of the soil with oxygen and a proper disposal of the exhaled carbon dioxide are essential for an undisturbed root respiration. If the soil surface is smeared, compacted or sealed, soil aeration is interrupted. Several references show that root activity and fine root growth are controlled by the carbon dioxide concentration in soil air (Qi et al.1994, Burton et al. 1997). Gaertig (2001) found that decreasing topsoil gas permeability leads to reduced fine root density and hence to injury in crown structure of oaks. In forest soils a critical CO2 concentration of more than 0.6 % indicates a bad aeration status (Gaertig 2001). The majority of urban tree sites are compacted or sealed. The reduction of soil aeration may lead to dysfunctions in the root space and consequently to stress during periods of drought, which has its visible affects in crown structure. It is reasonable to assume that disturbances in soil aeration lead to reduced tree vigour and roadworthiness, resulting in high maintenance costs. The assessment of soil aeration in urban sites is difficult. In natural ecosystems the measurement of gas diffusivity and the gas-chromatical analysis of CO2 in soil air are accepted procedures in analyzing the state of aeration (Schack-Kirchner et al. 2001, Gaertig 2001). It has been found that these methods can also be applied for analyzing urban sites. In particular CO2 concentration in the soil atmosphere can be considered as a rapidly assessable, relevant and integrating indicator of the aeration situation of urban soils. This study tested the working hypothesis that soil aeration deficiencies lead to a decrease of fine root density and tree vigour on urban soils. For that purpose gas diffusivity, soil CO2 concentrations and fine root density were measured on typical urban sites in the German cities of Göttingen, Mannheim, and Kassel. The known characteristics of soil aeration on forest sites could be affirmed for urban soils. A negative correlation was found between gas diffusion coefficients and CO2 concentration as well as between fine root extension and CO2 concentration. Changes in crown structure of beech indicating a loss of vigour were found at sites with disturbed aeration. Diffusivity patterns and CO2 concentrations of different specific urban soil sealing types were found. On more natural sites (mulch, grass) increased gas diffusion and low CO2 concentration were present. In contrast, on more compacted or sealed areas (asphalt, paving stone, macadamised road surface) the exchange between soil air and atmosphere was nearly disconnected and soil CO2 concentrations partly exceeded the known critical value of 0.6 % up to tenfold. Literature Burton, A. J.; Pregitzer, K. S.; Zogg, G. P. und Zak D. R. (1997): Effect of measurement CO2 concentrations on sugar maple root respiration. In: Canadian journal of Forest Research, H. 17, S. 421-427. Gaertig, T. (2001): Bodengashaushalt, Feinwurzeln und Vitalität von Eichen. In: Freiburger Bodenkundliche Abhandlungen, H. 40, S. 157. Qi, J.; Marshall, J. D.; Mattson, K. G. (1994): High soil carbon dioxide concentrations inhibit root respiration of Douglas fir. In: New Phytol., Jg. 128, H. 3, S. 435-442. Schack-Kirchner, H.; Gaertig, T.; Wilpert, K. v.; Hildebrand, E. E. (2001): A modified McIntyre and Phillip approach to measure top-soil gas diffusivity in-situ. In: J. Plant Nutr. Soil Sci., Jg. 164, S. 253-258.

Response of plant nutrient stoichiometry to fertilization varied with plant tissues in a tropical forest

PubMed Central

Mo, Qifeng; Zou, Bi; Li, Yingwen; Chen, Yao; Zhang, Weixin; Mao, Rong; Ding, Yongzhen; Wang, Jun; Lu, Xiankai; Li, Xiaobo; Tang, Jianwu; Li, Zhian; Wang, Faming

2015-01-01

Plant N:P ratios are widely used as indices of nutrient limitation in terrestrial ecosystems, but the response of these metrics in different plant tissues to altered N and P availability and their interactions remains largely unclear. We evaluated changes in N and P concentrations, N:P ratios of new leaves (<1 yr), older leaves (>1 yr), stems and mixed fine roots of seven species after 3-years of an N and P addition experiment in a tropical forest. Nitrogen addition only increased fine root N concentrations. P addition increased P concentrations among all tissues. The N × P interaction reduced leaf and stem P concentrations, suggesting a negative effect of N addition on P concentrations under P addition. The reliability of using nutrient ratios as indices of soil nutrient availability varied with tissues: the stoichiometric metrics of stems and older leaves were more responsive indicators of changed soil nutrient availability than those of new leaves and fine roots. However, leaf N:P ratios can be a useful indicator of inter-specific variation in plant response to nutrients availability. This study suggests that older leaf is a better choice than other tissues in the assessment of soil nutrient status and predicting plant response to altered nutrients using nutrients ratios. PMID:26416169

Does mycorrhizal inoculation improve plant survival, aggregate stability, and fine root development on a coarse-grained soil in an alpine eco-engineering field experiment?

NASA Astrophysics Data System (ADS)

Bast, A.; Wilcke, W.; Graf, F.; Lüscher, P.; Gärtner, H.

2016-08-01

Steep vegetation-free talus slopes in high mountain environments are prone to superficial slope failures and surface erosion. Eco-engineering measures can reduce slope instabilities and thus contribute to risk mitigation. In a field experiment, we established mycorrhizal and nonmycorrhizal research plots and determined their biophysical contribution to small-scale soil fixation. Mycorrhizal inoculation impact on plant survival, aggregate stability, and fine root development was analyzed. Here we present plant survival (ntotal = 1248) and soil core (ntotal = 108) analyses of three consecutive years in the Swiss Alps. Soil cores were assayed for their aggregate stability coefficient (ASC), root length density (RLD), and mean root diameter (MRD). Inoculation improved plant survival significantly, but it delayed aggregate stabilization relative to the noninoculated site. Higher aggregate stability occurred only after three growing seasons. Then also RLD tended to be higher and MRD increased significantly at the mycorrhizal treated site. There was a positive correlation between RLD, ASC, and roots <0.5 mm, which had the strongest impact on soil aggregation. Our results revealed a temporal offset between inoculation effects tested in laboratory and field experiments. Consequently, we recommend to establish an intermediate to long-term field experimental monitoring before transferring laboratory results to the field.

Reduction of Cr(VI) to Cr(III) by wetland plants: Potential for in situ heavy metal detoxification

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

Lytle, C.M.; Qian, J.H.; Hansen, D.

1998-10-15

Reduction of heavy metals in situ by plants may be a useful detoxification mechanism for phytoremediation. Using X-ray spectroscopy, the authors show that Eichhornia crassipes (water hyacinth), supplied with Cr(VI) in nutrient culture, accumulated nontoxic Cr(III) in root and shoot tissues. The reduction of Cr(VI) to Cr(III) appeared to occur in the fine lateral roots. The Cr(III) was subsequently translocated to leaf tissues. Extended X-ray absorption fine structure of Cr in leaf and petiole differed when compared to Cr in roots. In roots, Cr(III) was hydrated by water, but in petiole and more so in leaf, a portion of themore » Cr(III) may be bound to oxalate ligands. This suggests that E. crassipes detoxified Cr(VI) upon root uptake and transported a portion of the detoxified Cr to leaf tissues. Cr-rich crystalline structures were observed on the leaf surface. The chemical species of Cr in other plants, collected from wetlands that contained Cr(VI)-contaminated wastewater, was also found to be Cr(III). The authors propose that this plant-based reduction of Cr(VI) by E. crassipes has the potential to be used for the in situ detoxification of Cr(VI)-contaminated wastestreams.« less

DO ELEVATED CO2 AND N FERTILIZATION ALTER FINE ROOT-MYCORRHIZAE RELATIONSHIPS IN PINUS PONDEROSA?

EPA Science Inventory

Despite extensive studies on the response of plants to elevated CO2, climate change and N deposition, little is known about the response of roots and mycorrhizae in spite of their key role in plant water and nutrient acquisition. The effects of elevated CO2 and N fertilization on...

Seasonal Fine Root Carbohydrate Relations of Plantation Loblolly Pine After Thinning

Treesearch

Mary A. Sword; Eric A. Kuehler; Zhenmin Tang

2000-01-01

Loblolly pine (Pinus taeda L.) occurs naturally on soils that are frequently low in fertility and water availability (Allen et al., 1990; Schultz 1997). Despite these limitations, this species maintains a high level of productivity on most sites (Schultz, 1997). Knowledge of plantation loblolly pine root system growth and physiology is needed to...

Chemistry and long-term decomposition of roots from Douglas-fir grown at elevated atmospheric CO2 and warming conditions

EPA Science Inventory

Elevated atmospheric CO2 and warming may affect litter quality of plants and its subsequent decomposition in forested ecosystems. Little data are available to test this potential feedback on root tissues. In this study, we used the fine (diameter ≤ 2 mm) and small (2-10 mm) roo...

Arbuscule frequency in grapevine roots is more responsive to reduction in photosynthetic capacity than to increased levels of shoot phosphorus

USDA-ARS?s Scientific Manuscript database

We evaluated whether altering photosynthetic capacity or shoot P plays bigger role in regulating arbuscule abundance in fine roots of grapevine. Pinot noir grapevines were grown in an unsterilized vineyard soil and colonized by indigenous arbuscular mycorrhizal fungi (AMF) in two experiments where p...

Simulated Nitrogen Deposition has Minor Effects on Ecosystem Pools and Fluxes of Energy, Elements, and Biochemicals in a Northern Hardwoods Forest

NASA Astrophysics Data System (ADS)

Talhelm, A. F.; Pregitzer, K. S.; Burton, A. J.; Xia, M.; Zak, D. R.

2017-12-01

The elemental and biochemical composition of plant tissues is an important influence on primary productivity, decomposition, and other aspects of biogeochemistry. Human activity has greatly altered biogeochemical cycles in ecosystems downwind of industrialized regions through atmospheric nitrogen deposition, but most research on these effects focuses on individual elements or steps in biogeochemical cycles. Here, we quantified pools and fluxes of biomass, the four major organic elements (carbon, oxygen, hydrogen, nitrogen), four biochemical fractions (lignin, structural carbohydrates, cell walls, and soluble material), and energy in a mature northern hardwoods forest in Michigan. We sampled the organic and mineral soil, fine and coarse roots, leaf litter, green leaves, and wood for chemical analyses. We then combined these data with previously published and archival information on pools and fluxes within this forest, which included replicated plots receiving either ambient deposition or simulated nitrogen deposition (3 g N m-2 yr-1 for 18 years). Live wood was the largest pool of energy and all elements and biochemical fractions. However, the production of wood, leaf litter, and fine roots represented similar fluxes of carbon, hydrogen, oxygen, cell wall material, and energy, while nitrogen fluxes were dominated by leaf litter and fine roots. Notably, the flux of lignin via fine roots was 70% higher than any other flux. Experimental nitrogen deposition had relatively few significant effects, increasing foliar nitrogen, increasing the concentration of lignin in the soil organic horizon and decreasing pools of all elements and biochemical fractions in the soil organic horizon except nitrogen, lignin, and structural carbohydrates. Overall, we found that differences in tissue chemistry concentrations were important determinants of ecosystem-level pools and fluxes, but that nitrogen deposition had little effect on concentrations, pools, or fluxes in this mature forest. Disclaimer: The views expressed in this poster are those of the authors and do not necessarily represent the views or policies of the U.S. EPA.

Visual illusion in mass estimation of cut food.

PubMed

Wada, Yuji; Tsuzuki, Daisuke; Kobayashi, Naoki; Hayakawa, Fumiyo; Kohyama, Kaoru

2007-07-01

We investigated the effect of the appearance of cut food on visual mass estimation. In this experiment, we manipulated the shape (e.g., a block, fine strips, or small cubes) of food samples of various masses, and presented them on a CRT display as stimuli. Eleven subjects participated in tasks to choose the picture of the food sample which they felt indicated a target mass. We used raw carrots and surimi (ground fish) gel as hard and soft samples, respectively. The results clearly confirm an existence of an illusion, and this indicates that the appearance of food interferes with visual mass estimation. Specifically, participants often overestimated the mass of finely cut food, especially fine strips, whereas they could accurately estimate the mass of block samples, regardless of the physical characteristics of the foods. The overestimation of the mass of cut food increased with the food's actual mass, and was particularly obvious with increases of apparent volume when cut into fine strips. These results suggest that the apparent volume of a food sample effects the visual estimation of its mass. Hence we can conclude that there are illusions associated with the visual presentation of food that may influence various food impressions, including satisfaction and eating behaviour.

[Effects and mechanisms of plant roots on slope reinforcement and soil erosion resistance: a research review].

PubMed

Xiong, Yan-Mei; Xia, Han-Ping; Li, Zhi-An; Cai, Xi-An

2007-04-01

Plant roots play an important role in resisting the shallow landslip and topsoil erosion of slopes by raising soil shear strength. Among the models in interpreting the mechanisms of slope reinforcement by plant roots, Wu-Waldron model is a widely accepted one. In this model, the reinforced soil strength by plant roots is positively proportional to average root tensile strength and root area ratio, the two most important factors in evaluating slope reinforcement effect of plant roots. It was found that soil erosion resistance increased with the number of plant roots, though no consistent quantitative functional relationship was observed between them. The increase of soil erosion resistance by plant roots was mainly through the actions of fiber roots less than 1 mm in diameter, while fiber roots enhanced the soil stability to resist water dispersion via increasing the number and diameter of soil water-stable aggregates. Fine roots could also improve soil permeability effectively to decrease runoff and weaken soil erosion.

Paleosols can promote root growth of the recent vegetation - a case study from the sandy soil-sediment sequence Rakt, the Netherlands

NASA Astrophysics Data System (ADS)

Gocke, M. I.; Kessler, F.; van Mourik, J. M.; Jansen, B.; Wiesenberg, G. L. B.

2015-12-01

Soil studies commonly comprise the uppermost meter for tracing e.g. soil development. However, the maximum rooting depth of various plants significantly exceeds this depth. We hypothesized that deeper parts of the soil, soil parent material and especially paleosols provide beneficial conditions in terms of e.g. nutrient contents, thus supporting their utilization and exploitation by deep roots. We aimed to decipher the different phases of soil formation in Dutch drift- and coversands. The study site is located at Bedafse Bergen (SE Netherlands) in a 200 year old oak stand. A recent Podzol developed on driftsand covering a Plaggic Anthrosol that established in a relict Podzol on Late Glacial eolian coversand. Root-free soil and sediment samples, collected in 10-15 cm depth increments, were subjected to a multi-proxy physical and geochemical approach. The Plaggic Anthrosol revealed low bulk density and high phosphorous and organic carbon contents, whereas the relict Podzol was characterized by high iron and aluminum contents. Frequencies of fine (≤ 2 mm) and medium roots (2-5 mm) were determined on horizontal levels and the profile wall for a detailed pseudo-three-dimensional insight. On horizontal levels, living roots maximized in the uppermost part of the relict Podzol with ca. 4450 and 220 m-2, significantly exceeding topsoil root abundances. Roots of oak trees thus benefited from the favorable growth conditions in the nutrient-rich Plaggic Anthrosol, whereas increased compactness and high aluminum contents of the relict Podzol caused a strong decrease of roots. The approach demonstrated the benefit of comprehensive root investigation to support and explain pedogenic investigations of soil profiles, as fine roots can be significantly underestimated when quantified at the profile wall. The possible rooting of soil parent material and paleosols long after their burial confirmed recent studies on the potential influence of rooting to overprint sediment-(paleo)soil sequences of various ages, sedimentary and climatic settings. Potential consequences of deep rooting for terrestrial deep carbon stocks, located to a relevant part in paleosols, remain largely unknown and require further investigation.

Paleosols can promote root growth of recent vegetation - a case study from the sandy soil-sediment sequence Rakt, the Netherlands

NASA Astrophysics Data System (ADS)

Gocke, Martina I.; Kessler, Fabian; van Mourik, Jan M.; Jansen, Boris; Wiesenberg, Guido L. B.

2016-10-01

Soil studies commonly comprise the uppermost meter for tracing, e.g., soil development. However, the maximum rooting depth of various plants significantly exceeds this depth. We hypothesized that deeper parts of the soil, soil parent material and especially paleosols provide beneficial conditions in terms of, e.g., nutrient contents, thus supporting their utilization and exploitation by deep roots. We aimed to decipher the different phases of soil formation in Dutch drift sands and cover sands. The study site is located at Bedafse Bergen (southeastern Netherlands) in a 200-year-old oak stand. A recent Podzol developed on drift sand covering a Plaggic Anthrosol that was piled up on a relict Podzol on Late Glacial eolian cover sand. Root-free soil and sediment samples, collected in 10-15 cm depth increments, were subjected to a multi-proxy physical and geochemical approach. The Plaggic Anthrosol revealed low bulk density and high phosphorous and organic carbon contents, whereas the relict Podzol was characterized by high iron and aluminum contents. Frequencies of fine (diameter ≤ 2 mm) and medium roots (2-5 mm) were determined on horizontal levels and the profile wall for a detailed pseudo-three-dimensional insight. On horizontal levels, living roots were most abundant in the uppermost part of the relict Podzol with ca. 4450 and 220 m-2, significantly exceeding topsoil root abundances. Roots of oak trees thus benefited from the favorable growth conditions in the nutrient-rich Plaggic Anthrosol, whereas increased compactness and high aluminum contents of the relict Podzol caused a strong decrease of roots. The approach demonstrated the benefit of comprehensive root investigation to support interpretation of soil profiles, as fine roots can be significantly underestimated when quantified at the profile wall. The possible rooting of soil parent material and paleosols long after their burial confirmed recent studies on the potential influence of rooting to overprint sediment-(paleo)soil sequences of various ages, sedimentary and climatic settings. Potential consequences of deep rooting for terrestrial deep carbon stocks, located to a relevant part in paleosols, remain largely unknown and require further investigation.

Classroom Modified Split-Root Technique and Its Application in a Plant Habitat Selection Experiment at the College Level

ERIC Educational Resources Information Center

Elliott, Shannon S.; Winter, Peggy A.

2011-01-01

The split-root technique produces a plant with two equal root masses. Traditionally, the two root masses of the single plant are cultivated in adjacent pots with or without roots from competitors for the purpose of elucidating habitat preferences. We have tailored this technology for the classroom, adjusting protocols to match resources and time…

Fine Structure of Bacteroids in Root Nodules of Vigna sinensis, Acacia longifolia, Viminaria juncea, and Lupinus angustifolius

PubMed Central

Dart, P. J.; Mercer, F. V.

1966-01-01

Dart, P. J. (University of Sydney, Sydney, Australia), and F. V. Mercer. Fine structure of bacteroids in root nodules of Vigna sinensis, Acacia longifolia, Viminaria juncea, and Lupinus angustifolius. J. Bacteriol. 91:1314–1319.—In nodules of Vigna sinensis, Acacia longifolia, and Viminaria juncea, membrane envelopes enclose groups of bacteroids. The bacteroids often contain inclusion granules and electron-dense bodies, expand little during development, and retain their rod form with a compact, central nucleoid area. The membrane envelope may persist around bacteroids after host cytoplasm breakdown. In nodules of Lupinus angustifolius, the membrane envelopes enclose only one or two bacteroids, which expand noticeably during development and change from their initial rod structure. Images PMID:5929757

Effects of nutrient patches and root systems on the clonal plasticity of a rhizomatous grass

USGS Publications Warehouse

Huber-Sannwald, Elisabeth; Pyke, David A.; Caldwell, M.M.; Durham, S.

1998-01-01

Clonal plant foraging has been examined primarily on individual clones exposed to resource-poor and resource-rich environments. We designed an experiment to examine the clonal foraging behavior of the rhizomatous grass Elymus lanceolatus ssp. lanceolatus under the influence of neighboring plant root systems in a heterogeneous nutrient environment. Individual Elymus clones were planted in large bins together with one of three neighboring grass species, Agropyron desertorum, Pseudoroegneria spicata, or Bromus tectorum, which differ in rooting density and growth activity. The position of Elymus clones was manipulated so rhizomes encountered a short-duration nutrient patch and subsequently root systems of the neighboring plants. Unexpectedly, the morphological plasticity of the perennial grass Elymus lanceolatus ssp. lanceolatus was influenced by the presence of the neighboring species much more than by the local nutrient enrichments, although nutrient patches did amplify some of the foraging responses. Elymus rhizomes branched readily and initiated large daughter plants as they encountered the low-density root systems of Pseudoroegneria. When Elymus encountered the fine, dense root systems of the annual Bromus, clonal expansion was initially reduced. Yet, after the short growing season of Bromus, Elymus resumed clonal expansion and produced several daughter plants. Elymus clones were most constrained by the fine, dense root systems of Agropyron desertorum. In this case, a few, long rhizomes avoided the densely rooted soil environment by growing aboveground as stolons crossing over the Agropyron tussocks. Elymus clonal biomass was largest in neighborhoods of Pseudoroegneria, intermediate in neighborhoods with Bromus, and smallest in neighborhoods with Agropyron. The latter were approximately half the size of those in the Pseudoroegneria environments. Elymus growth could not be explained by simple resource competition alone; other mechanisms must have been involved in the apparent differences in interference patterns of neighboring plants with Elymus.

Aquaporin-mediated changes in hydraulic conductivity of deep tree roots accessed via caves.

PubMed

McElrone, Andrew J; Bichler, Justin; Pockman, William T; Addington, Robert N; Linder, C Randal; Jackson, Robert B

2007-11-01

Although deep roots can contribute substantially to whole-tree water use, little is known about deep root functioning because of limited access for in situ measurements. We used a cave system on the Edwards Plateau of central Texas to investigate the physiology of water transport in roots at 18-20 m depth for two common tree species, Quercus fusiformis and Bumelia lanuginosa. Using sap flow and water potential measurements on deep roots, we found that calculated root hydraulic conductivity (RHC) fluctuated diurnally for both species and decreased under shading for B. lanuginosa. To assess whether these dynamic changes in RHC were regulated during initial water absorption by fine roots, we used an ultra-low flowmeter and hydroxyl radical inhibition to measure in situ fine root hydraulic conductivity (FRHC) and aquaporin contribution to FRHC (AQPC), respectively. During the summer, FRHC and AQPC were found to cycle diurnally in both species, with peaks corresponding to the period of highest transpirational demand at midday. During whole-tree shade treatments, B. lanuginosa FRHC ceased diurnal cycling and decreased by 75 and 35% at midday and midnight, respectively, while AQPC decreased by 41 and 30% during both time periods. A controlled growth-chamber study using hydroponically grown saplings confirmed daily cycling and shade-induced reductions in FRHC and AQPC. Winter measurements showed that the evergreen Q. fusiformis maintained high FRHC and AQPC throughout the year, while the deciduous B. lanuginosa ceased diurnal cycling and exhibited its lowest annual values for both parameters in winter. Adjustments in FRHC and AQPC to changing canopy water demands may help the trees maintain the use of reliable water resources from depth and contribute to the success of these species in this semi-arid environment.

Source apportionment of airborne particulate matter using organic compounds as tracers

NASA Astrophysics Data System (ADS)

Schauer, James J.; Rogge, Wolfgang F.; Hildemann, Lynn M.; Mazurek, Monica A.; Cass, Glen R.; Simoneit, Bernd R. T.

A chemical mass balance receptor model based on organic compounds has been developed that relates source contributions to airborne fine particle mass concentrations. Source contributions to the concentrations of specific organic compounds are revealed as well. The model is applied to four air quality monitoring sites in southern California using atmospheric organic compound concentration data and source test data collected specifically for the purpose of testing this model. The contributions of up to nine primary particle source types can be separately identified in ambient samples based on this method, and approximately 85% of the organic fine aerosol is assigned to primary sources on an annual average basis. The model provides information on source contributions to fine mass concentrations, fine organic aerosol concentrations and individual organic compound concentrations. The largest primary source contributors to fine particle mass concentrations in Los Angeles are found to include diesel engine exhaust, paved road dust, gasoline-powered vehicle exhaust, plus emissions from food cooking and wood smoke, with smaller contribution from tire dust, plant fragments, natural gas combustion aerosol, and cigarette smoke. Once these primary aerosol source contributions are added to the secondary sulfates, nitrates and organics present, virtually all of the annual average fine particle mass at Los Angeles area monitoring sites can be assigned to its source.

Source apportionment of airborne particulate matter using organic compounds as tracers

NASA Astrophysics Data System (ADS)

Schauer, James J.; Rogge, Wolfgang F.; Hildemann, Lynn M.; Mazurek, Monica A.; Cass, Glen R.; Simoneit, Bernd R. T.

A chemical mass balance receptor model based on organic compounds has been developed that relates sours; contributions to airborne fine particle mass concentrations. Source contributions to the concentrations of specific organic compounds are revealed as well. The model is applied to four air quality monitoring sites in southern California using atmospheric organic compound concentration data and source test data collected specifically for the purpose of testing this model. The contributions of up to nine primary particle source types can be separately identified in ambient samples based on this method, and approximately 85% of the organic fine aerosol is assigned to primary sources on an annual average basis. The model provides information on source contributions to fine mass concentrations, fine organic aerosol concentrations and individual organic compound concentrations. The largest primary source contributors to fine particle mass concentrations in Los Angeles are found to include diesel engine exhaust, paved road dust, gasoline-powered vehicle exhaust, plus emissions from food cooking and wood smoke, with smaller contribution:; from tire dust, plant fragments, natural gas combustion aerosol, and cigarette smoke. Once these primary aerosol source contributions are added to the secondary sulfates, nitrates and organics present, virtually all of the annual average fine particle mass at Los Angeles area monitoring sites can be assigned to its source.

Early impacts of forest restoration treatments on the ectomycorrhizal fungal community and fine root biomass in a mixed conifer forest.

Treesearch

Jane E. Smith; Donaraye McKay; Greg Brenner; Jim McIver; Joseph W. Spatafora

2005-01-01

1. The obligate symbiosis formed between ectomycorrhizal fungi (EMF) and roots of tree species in the Pinaceae influences nutrient uptake and surrounding soil structure. Understanding how EMF respond to prescribed fire and thinning will assist forest managers in selecting fuel-reducing restoration treatments that maintain critical soil processes and site productivity....

Aquatic Plants Aid Sewage Filter

NASA Technical Reports Server (NTRS)

Wolverton, B. C.

1985-01-01

Method of wastewater treatment combines micro-organisms and aquatic plant roots in filter bed. Treatment occurs as liquid flows up through system. Micro-organisms, attached themselves to rocky base material of filter, act in several steps to decompose organic matter in wastewater. Vascular aquatic plants (typically, reeds, rushes, cattails, or water hyacinths) absorb nitrogen, phosphorus, other nutrients, and heavy metals from water through finely divided roots.

How does fire affect longleaf pine roots carbohydrates, foliar nutrients, and sapling growth?

Treesearch

Eric A. Kuehler; Marry Anne Sword Sayer; C. Dan Andries

2006-01-01

In central Louisiana, we conducted a prescribed-fire study in a 5-year-old longleaf pine (Pinus palustris P. Mill.) stand to evaluate the effects of fire on fine-root (2- to 5-mm diameter) carbohydrates, dormant season foliar nutrients, and sapling growth. Control, burn, and nonburned vegetation control treatments were studied using a randomized...

Climate warming shifts carbon allocation from stemwood to roots in calcium-depleted spruce forests

Treesearch

Andrei G. ​Lapenis; Gregory B. Lawrence; Alexander Heim; Chengyang Zheng; Walter Shortle

2013-01-01

Increased greening of northern forests, measured by the Normalized Difference Vegetation Index (NDVI), has been presented as evidence that a warmer climate has increased both net primary productivity (NPP) and the carbon sink in boreal forests. However, higher production and greener canopies may accompany changes in carbon allocation that favor foliage or fine roots...

Seasonal branch and fine root growth of juvenile loblolly pine five growing seasons after fertilization

Treesearch

M.A. Sword; D.A. Gravatt; P.L. Faulkner; J.L. Chambers

1996-01-01

In 1989, we established two replications of two fertilization treatments in a 10-year-old loblolly pine (Pinus taeda L.) plantation. Between March and September 1993, branch internode and needle fascicle expansion in the upper and lower third of crowns were measured weekly on three south-facing branches of each of four trees, and new root...

Below-ground carbon input to soil is controlled by nutrient availability and fine root dynamics in loblolly pine

Treesearch

John S. King; Timothy J. Albaugh; H. Lee Allen; Boyd R. Strain; Phillip Dougherty

2002-01-01

Availability of growth limiting resources may alter root dynamics in forest ecosystems, possibly affecting the land-atmosphere exchange of carbon. This was evaluated for a commercially important southern timber species by installing a factorial experiment of fertilization and irrigation treatments in an 8-yr-old loblolly pine (Pinus taeda) plantation...

Association mapping provides insights into the origin and the fine structure of the sorghum aluminum tolerance locus, AltSB

USDA-ARS?s Scientific Manuscript database

Root damage caused by aluminum (Al) toxicity is a major cause of grain yield reduction on acid soils, which are prevalent in tropical and subtropical regions of the world where food security is most tenuous. In sorghum, Al tolerance is conferred by SbMATE, an Al-activated root citrate efflux transpo...

[Soil infiltration characteristics under main vegetation types in Anji County of Zhejiang Province].

PubMed

Liu, Dao-Ping; Chen, San-Xiong; Zhang, Jin-Chi; Xie, Li; Jiang, Jiang

2007-03-01

The study on the soil infiltration under different main vegetation types in Anji County of Zhejiang Province showed that the characteristics of soil infiltration differed significantly with land use type, and the test eight vegetation types could be classified into four groups, based on soil infiltration capability. The first group, deciduous broadleaved forest, had the strongest soil infiltration capability, and the second group with a stronger soil infiltration capability was composed of grass, pine forest, shrub community and tea bush. Bamboo and evergreen broadleaved forest were classified into the third group with a relatively strong soil infiltration capability, while bare land belonged to the fourth group because of the bad soil structure and poorest soil infiltration capability. The comprehensive parameters of soil infiltration (alpha) and root (beta) were obtained by principal component analysis, and the regression model of alpha and beta could be described as alpha = 0. 1708ebeta -0. 3122. Soil infiltration capability was greatly affected by soil physical and chemical characteristics and root system. Fine roots (< or = 1 mm in diameter) played effective roles on the improvement of soil physical and chemical properties, and the increase of soil infiltration capability was closely related to the amount of the fine roots.

The symbiotic relationship between dominant canopy trees and soil microbes affects the nitrogen source utilization of co-existing understory trees

NASA Astrophysics Data System (ADS)

Iwaoka, C.; Hyodo, F.; Taniguchi, T.; Shi, W.; Du, S.; Yamanaka, N.; Tateno, R.

2017-12-01

The symbiotic relationship between dominant canopy trees and soil microbes such as mycorrhiza or nitrogen (N) fixer are important determinants of soil N dynamics of a forest. However, it is not known how and to what extent the symbiotic relationship of dominant canopy trees with soil microbes affect the N source of co-existing trees in forest. We measured the δ15N of surface soils (0-10 cm), leaves, and roots of the dominant canopy trees and common understory trees in an arbuscular mycorrhizal N-fixing black locust (Robinia pseudoacacia) plantation and an ectomycorrhizal oak (Quercus liaotungensis) natural forest in a China dryland. We also analyzed the soil dissolved N content in soil extracts and absorbed by ion exchange resin, and soil ammonia-oxidizer abundance using real-time PCR. The δ15N of soil and leaves were higher in the black locust forest than in the oak forest, although the δ15N of fine roots was similar in the two forests, in co-existing understory trees as well as dominant canopy trees. Accordingly, the δ15N of leaves was similar to or higher than that of fine roots in the black locust forest, whereas it was consistently lower than that of fine roots in the oak forest. In the black locust forest, the soil dissolved organic N and ammonium N contents were less abundant but the nitrate N contents in soils and absorbed by the ion exchange resin and ammonia-oxidizer abundance were greater, due to N fixation or less uptake of organic N from arbuscular mycorrhiza. In contrast, the soil dissolved organic N and ammonium N contents were more abundant in the oak forest, whereas the N content featured very low nitrate, due to ectomycorrhizal ability to access organic N. These results suggest that the main N source is nitrate N in the black locust forest, but dissolved organic N or ammonium N in the oak forest. N fixation or high N loss due to high N availability would cause high δ15N in soil and leaves in black locust forest. On the other hand, low soil N availability in the oak forest may make 15N fractionation more active in roots via mycorrhizal association, resulting in higher δ15N in fine roots than in leaves. In conclusion, the symbiotic relationship between dominant canopy trees and soil microbes affected the N source of not only the dominant trees but also co-existing understory trees via the control of soil N dynamics.

DynamicRoots: A Software Platform for the Reconstruction and Analysis of Growing Plant Roots.

PubMed

Symonova, Olga; Topp, Christopher N; Edelsbrunner, Herbert

2015-01-01

We present a software platform for reconstructing and analyzing the growth of a plant root system from a time-series of 3D voxelized shapes. It aligns the shapes with each other, constructs a geometric graph representation together with the function that records the time of growth, and organizes the branches into a hierarchy that reflects the order of creation. The software includes the automatic computation of structural and dynamic traits for each root in the system enabling the quantification of growth on fine-scale. These are important advances in plant phenotyping with applications to the study of genetic and environmental influences on growth.

The Early Entry of Al into Cells of Intact Soybean Roots (A Comparison of Three Developmental Root Regions Using Secondary Ion Mass Spectrometry Imaging).

PubMed Central

Lazof, D. B.; Goldsmith, J. G.; Rufty, T. W.; Linton, R. W.

1996-01-01

Al localization was compared in three developmental regions of primary root of an Al-sensitive soybean (Glycine max) genotype using secondary ion mass spectrometry. In cryosections obtained after a 4-h exposure to 38 [mu]M [Al3+], Al had penetrated across the root and into the stele in all three regions. Although the greatest localized Al concentration was consistently at the root periphery, the majority of the Al in each region had accumulated in cortical cells. It was apparent that the secondary ion mass spectrometry 27Al+ mass signal was spread throughout the intracellular area and was not particularly intense in the cell wall. Inclusion of some cell wall in determinations of the Al levels across the root radius necessitated that these serve as minimal estimates for intracellular Al. Total accumulation of intracellular Al for each region was 60, 73, and 210 nmol g-1 fresh weight after 4 h, increasing with root development. Early metabolic responses to external Al, including those that have been reported deep inside the root and in mature regions, might result directly from intracellular Al. These responses might include ion transport events at the endodermis of mature roots or events associated with lateral root emergence, as well as events within the root tip. PMID:12226447

Net ammonium and nitrate fluxes in wheat roots under different environmental conditions as assessed by scanning ion-selective electrode technique

PubMed Central

Zhong, Yangquanwei; Yan, Weiming; Chen, Juan; Shangguan, Zhouping

2014-01-01

Wheat is one of the most important food crops in the world, its availability affects global food security. In this study, we investigated variations in NH4+ and NO3- fluxes in the fine roots of wheat using a scanning ion-selective electrode technique in the presence of different nitrogen (N) forms, N concentrations, and pH levels as well as under water stress. Our results show that the fine roots of wheat demonstrated maximum NH4+ and NO3− influxes at 20 mm and 25 mm from the root tip, respectively. The maximal net NH4+ and NO3− influxes were observed at pH 6.2 in the presence of a 1/4 N solution. We observed N efflux in two different cultivars following the exposure of roots to a 10% PEG-6000 solution. Furthermore, the drought-tolerant cultivar generally performed better than the drought-intolerant cultivar. Net NH4+ and NO3− fluxes may be determined by plant growth status, but environmental conditions can also affect the magnitude and direction of N flux. Interestingly, we found that NO3− was more sensitive to environmental changes than NH4+. Our results may be used to guide future hydroponic experiments in wheat as well as to aid in the development of effective fertilisation protocols for this crop. PMID:25428199

Aboveground Tree Growth Varies with Belowground Carbon Allocation in a Tropical Rainforest Environment

PubMed Central

Raich, James W.; Clark, Deborah A.; Schwendenmann, Luitgard; Wood, Tana E.

2014-01-01

Young secondary forests and plantations in the moist tropics often have rapid rates of biomass accumulation and thus sequester large amounts of carbon. Here, we compare results from mature forest and nearby 15–20 year old tree plantations in lowland Costa Rica to evaluate differences in allocation of carbon to aboveground production and root systems. We found that the tree plantations, which had fully developed, closed canopies, allocated more carbon belowground - to their root systems - than did mature forest. This increase in belowground carbon allocation correlated significantly with aboveground tree growth but not with canopy production (i.e., leaf fall or fine litter production). In contrast, there were no correlations between canopy production and either tree growth or belowground carbon allocation. Enhanced allocation of carbon to root systems can enhance plant nutrient uptake, providing nutrients beyond those required for the production of short-lived tissues such as leaves and fine roots, and thus enabling biomass accumulation. Our analyses support this deduction at our site, showing that enhanced allocation of carbon to root systems can be an important mechanism promoting biomass accumulation during forest growth in the moist tropics. Identifying factors that control when, where and for how long this occurs would help us to improve models of forest growth and nutrient cycling, and to ascertain the role that young forests play in mitigating increased atmospheric carbon dioxide. PMID:24945351

Net ammonium and nitrate fluxes in wheat roots under different environmental conditions as assessed by scanning ion-selective electrode technique.

PubMed

Zhong, Yangquanwei; Yan, Weiming; Chen, Juan; Shangguan, Zhouping

2014-11-27

Wheat is one of the most important food crops in the world, its availability affects global food security. In this study, we investigated variations in NH4(+) and NO3(-) fluxes in the fine roots of wheat using a scanning ion-selective electrode technique in the presence of different nitrogen (N) forms, N concentrations, and pH levels as well as under water stress. Our results show that the fine roots of wheat demonstrated maximum NH4(+) and NO3(-) influxes at 20 mm and 25 mm from the root tip, respectively. The maximal net NH4(+) and NO3(-) influxes were observed at pH 6.2 in the presence of a 1/4 N solution. We observed N efflux in two different cultivars following the exposure of roots to a 10% PEG-6000 solution. Furthermore, the drought-tolerant cultivar generally performed better than the drought-intolerant cultivar. Net NH4(+) and NO3(-) fluxes may be determined by plant growth status, but environmental conditions can also affect the magnitude and direction of N flux. Interestingly, we found that NO3(-) was more sensitive to environmental changes than NH4(+). Our results may be used to guide future hydroponic experiments in wheat as well as to aid in the development of effective fertilisation protocols for this crop.

[Seedling index of Salvia miltiorrhiza and its simulation model].

PubMed

Huang, Shu-Hua; Xu, Fu-Li; Wang, Wei-Ling; Du, Jun-Bo; Ru, Mei; Wang, Jing; Cao, Xian-Yan

2012-10-01

Through the correlation analysis on the quantitative traits and their ratios of Salvia miltiorrhiza seedlings and seedling quality, a series of representative indices reflecting the seedling quality of the plant species were determined, and the seedling index suitable to the S. miltiorrhiza seedlings was ascertained by correlation degree analysis. Meanwhile, based on the relationships between the seedling index and the air temperature, solar radiation and air humidity, a simulation model for the seedling index of S. miltiorrhiza was established. The experimental data of different test plots and planting dates were used to validate the model. The results showed that the root diameter, stem diameter, crown dry mass, root dry mass, and plant dry mass had significant positive relationships with the other traits, and could be used as the indicators of the seedling's health. The seedling index of S. miltiorrhiza could be calculated by (stem diameter/root diameter + root dry mass/crown dry mass) x plant dry mass. The stem diameter, root dry mass, crown dry mass and plant dry mass had higher correlations with the seedling index, and thus, the seedling index determined by these indicators could better reflect the seedling's quality. The coefficient of determination (R2) between the predicted and measured values based on 1:1 line was 0.95, and the root mean squared error (RMSE) was 0.15, indicating that the model established in this study could precisely reflect the quantitative relationships between the seedling index of S. miltiorrhiza and the environmental factors.

Characterization and mapping of very fine particles in an engine machining and assembly facility.

PubMed

Heitbrink, William A; Evans, Douglas E; Peters, Thomas M; Slavin, Thomas J

2007-05-01

Very fine particle number and mass concentrations were mapped in an engine machining and assembly facility in the winter and summer. A condensation particle counter (CPC) was used to measure particle number concentrations in the 0.01 microm to 1 microm range, and an optical particle counter (OPC) was used to measure particle number concentrations in 15 channels between 0.3 microm and 20 microm. The OPC measurements were used to estimate the respirable mass concentration. Very fine particle number concentrations were estimated by subtracting the OPC particle number concentrations from 0.3 microm to 1 microm from the CPC number concentrations. At specific locations during the summer visit, an electrical low pressure impactor was used to measure particle size distribution from 0.07 microm to 10 microm in 12 channels. The geometric mean ratio of respirable mass concentration estimated from the OPC to the gravimetrically measured mass concentration was 0.66 with a geometric standard deviation of 1.5. Very fine particle number concentrations in winter were substantially greater where direct-fire natural gas heaters were operated (7.5 x 10(5) particles/cm(3)) than where steam was used for heat (3 x 10(5) particles/cm(3)). During summer when heaters were off, the very fine particle number concentrations were below 10(5) particles/cm(3), regardless of location. Elevated very fine particle number concentrations were associated with machining operations with poor enclosures. Whereas respirable mass concentrations did not vary noticeably with season, they were greater in areas with poorly fitting enclosures (0.12 mg/m(3)) than in areas where state-of-the-art enclosures were used (0.03 mg/m(3)). These differences were attributed to metalworking fluid mist that escaped from poorly fitting enclosures. Particles generated from direct-fire natural gas heater operation were very small, with a number size distribution modal diameter of less than 0.023 microm. Aerosols generated by machining operations had number size distributions modes in the 0.023 microm to 0.1 microm range. However, multiple modes in the mass size distributions estimated from OPC measurements occurred in the 2-20 microm range. Although elevated, very fine particle concentrations and respirable mass concentrations were both associated with poorly enclosed machining operations; the operation of the direct-fire natural gas heaters resulted in the greatest very fine particle concentrations without elevating the respirable mass concentration. These results suggest that respirable mass concentration may not be an adequate indicator for very fine particle exposure.

Predicting first-year bare-root seedling establishment with soil and community dominance factors

Treesearch

Robin E. Durham; Benjamin A. Zamora; Michael R. Sackschewsky; Jason C. Ritter

2001-01-01

The usefulness of measuring community dominance factors and the soil parameters of geometric mean particle size and percent fines as predictors of first-year bare-root establishment of Wyoming big sagebrush seedlings was investigated. The study was conducted on six sandy soils in south-central Washington. Soil parameters that could affect the distribution of Sandberg’s...

Can ectomycorrhizal symbiosis and belowground plant traits be used as ecological tools to mitigate erosion on degraded slopes in the ultramafic soils of New Caledonia?

NASA Astrophysics Data System (ADS)

Demenois, Julien; Carriconde, Fabian; Rey, Freddy; Stokes, Alexia

2015-04-01

New Caledonia is an archipelago in the South West Pacific located just above the Tropic of Capricorn. The main island is bisected by a continuous mountain chain whose highest peaks reach more than 1 600 m. With mean annual rainfall above 2 000 mm in the South of the main island, frequent downpours and steep slopes, its soils are prone to water erosion. Deforestation, fires and mining activity are the main drivers of water erosion. Stakes are high to mitigate the phenomenon: extraction of nickel from ultramafic substrates (one third of the whole territory) is the main economic activity; New Caledonia is considered as a biodiversity hotspot. Restoration ecology is seen as a key approach for tackling such environmental challenges. Soil microorganisms could play significant roles in biological processes such as plant nutrition and plant resistance to abiotic and biotic stresses. Microorganisms could increase soil aggregate stability and thus mitigate soil erodibility. Plant roots increase soil cohesion through exudation and decomposition processes. To date, few studies have collected data on the soil aggregate stability of steep slopes affected by erosion and, to our knowledge, interactions between ectomycorrhizas (ECM), roots and erodibility of ultramafic soils have never been considered. The objective of our study is to assess the influence of ECM symbiosis and plant root traits on the erodibility of ultramafic soils of New Caledonia and answer the following questions: 1/ What is the influence of plant root traits of vegetal communities and ECM fungal diversity on soil erodibility? 2/ What are the belowground plant traits of some mycorrhized endemic species used in ecological restoration? 3/ What is the influence of plant root traits and ECM fungal inoculation on soil erodibility? At the scale of plant communities, five types of vegetation have been chosen in the South of the main island: degraded ligno-herbaceous shrubland, ligno-herbaceous shrubland, degraded humid forest with dominance of Arillastrum gummiferum, dense humid forest with dominance of Nothofagus aequilateralis, and finally mixed dense humid forest. These types of vegetation are widely represented on ultramafic soils of New Caledonia and are likely to correspond to different successional phases. At the scale of species, dominant species in the above-mentioned types of vegetation are considered for herbaceous, shrubs and trees strata. Root traits of Costularia nervosa, Tristaniopsis glauca, Nothofagus aequilateralis and Arillastrum gummiferum are then characterized in situ. These species are of particular interest for post-mining ecological restoration in New Caledonia as they are light-tolerant, endemic, associated with ECM (except for Costularia nervosa) and of particular interest or already used by mining operators for post-mining ecological restoration. For both scales (community and species), soil characteristics will be collected. Very fine and fine roots, mean root diameter, root diameter diversity, root mass density, root length density, and specific root length will be considered. Degree of ectomycorrhization and fungal biomass through qPCR will be determined. Soil aggregate stability will be measured according to the standardized method NF X 31-515. Besides, greenhouse trials with Costularia nervosa, Tristaniopsis glauca and Arillastrum gummiferum are carried out to assess the influence of plant root traits, fungal inoculation and soil aggregate stability. Controlled plant inoculations are performed using available pure fungal strains isolated from New Caledonian ultramafic soils. Plants have been bred on sterilized soil samples from the field sites. Through this study, we target to identify associations between ECM fungi and plant species that could mitigate the erodibility of degraded ultramafic soils and then water erosion. A better knowledge of interactions between soil aggregate stability, ECM fungi and plant root traits is then expected to answer the following question: can soil aggregate stability be used as a bio-indicator of ecosystem functioning and services?

Bud removal affects shoot, root, and callus development of hardwood Populus cuttings

Treesearch

A.H. Wiese; J.A. Zalesny; D.M. Donner; Ronald S., Jr. Zalesny

2006-01-01

The inadvertent removal and/or damage of buds during processing and planting of hardwood poplar (Populus spp.) cuttings are a concern because of their potential impact on shoot and root development during establishment. The objective of the current study was to test for differences in shoot dry mass, root dry mass, number of roots, length of the...

A preliminary investigation of projectile shape effects in hypervelocity impact of a double-sheet structure

NASA Technical Reports Server (NTRS)

Morrison, R. H.

1972-01-01

Impact tests of a sphere and several cylinders of various masses and fineness ratios, all of aluminum, fired into an aluminum double-sheet structure at velocities near 7 km/sec, show that a cylinder, impacting in the direction of its axis, is considerably more effective as a penetrator than a sphere. Impacts of three cylinders of equal mass, but different fineness ratios, produced holes through the structures' rear sheet, whereas impact of a sphere of the same mass did not. Moreover, it was found that to prevent rear-sheet penetration, the mass of the 1/2-fineness-ratio cylinder had to be reduced by a factor greater than three. Further tests wherein the cylinder diameter was held constant while the cylinder length was systematically reduced showed that a cylinder with a fineness ratio of 0.07 and a mass of only 1/7 that of the sphere was still capable of producing a hole in the rear sheet.

Variation in the concentration and age of nonstructural carbon stored in different tree tissues

NASA Astrophysics Data System (ADS)

Richardson, Andrew; Carbone, Mariah; Huggett, Brett; Furze, Morgan; Czimczik, Claudia I.; Xu, Xiaomei

2014-05-01

Trees store nonstructural carbon (NSC), in the form of sugars and starch, in the ray parenchyma cells of woody tissues. These reserves provide a carbon buffer when demand (growth, protection, or metabolism) exceeds supply (photosynthesis). This is particularly important in the context of resilience to stress and disturbance, such as might be associated with various global change factors. However, storage allocation processes and the availability of stored reserves remain poorly understood in woody plants. To better understand how NSC reserves are distributed throughout the tree, and the degree to which NSC reserves mix across ring boundaries and tissue types, we destructively sampled two 30-year-old trees (one red oak, Quercus rubra L., and one white pine, Pinus strobus L.) growing at Harvard Forest, an oak-dominated temperate forest in the northeastern United States. We analyzed stemwood samples (divided into individual rings, bark, and phloem), coarse and fine branches, and coarse (separated into three depths) and fine roots for concentrations of total sugars and starch. For a subset of samples we used the radiocarbon (14C) "bomb spike" method to estimate the mean age of extracted sugars and starch. In oak, stemwood sugar and starch concentrations were highest (50 mg/g) in the youngest (most recently-formed) rings, and dropped off rapidly (to 10 mg/g or less) across the 10 most recent rings. In oak phloem tissue, sugar concentrations were high (90 mg/g) compared to starch (10 mg/g). In pine, sugar concentrations dropped off rapidly across the three most recent rings (from 30 mg/g to 10 mg/g) whereas starch concentrations were low even for the youngest rings (10 mg/g or less). In pine, phloem concentrations of both sugar (190 mg/g) and starch (20 mg/g) were both substantially higher than in oak. Such strong radial trends must be accounted for when scaling up to whole-tree budgets, as whole increment cores cannot properly integrate (on a ring-area basis) across the depth profile. In oak, fine root concentrations of sugar and starch were similar (40 mg/g), and coarse roots had very high concentrations of starch (140 mg/g) compared to sugar (50 mg/g). In pine, fine root concentrations of both sugar and starch (60 mg/g) were higher than in coarse roots (10 mg/g). Coarse root NSC concentrations did not vary substantially along a radial gradient into the root. Even assuming a 1:5 root:shoot ratio, these data indicate that a large portion of the whole-tree NSC budget is stored belowground. For both sugars and starch, the 14C data indicated substantial mixing of new and older carbon across the youngest stemwood rings (up to 5 y), beyond which NSC age increased linearly with ring age. Coarse root NSC age also increased with radial depth and wood tissue age, and root NSC was consistently younger in pine than oak. The fact that NSC age is not constant with radial depth in the aboveground samples demonstrates that NSC reserves cannot be treated as a single, well-mixed pool. Rather, these results are consistent with previous observation suggesting last-in/first-out dynamics. From a modeling standpoint, these results support a simple two-pool structure where new photosynthate not used for current growth or metabolism enters a well-mixed and young "fast" pool, but over time storage in older rings is transferred to a distinct and older "slow" pool with which mixing no longer occurs.

Net Primary Productivity and Edaphic Fertility in Two Pluvial Tropical Forests in the Chocó Biogeographical Region of Colombia

PubMed Central

Quinto-Mosquera, Harley

2017-01-01

The net primary productivity (NPP) of tropical forests is a key process of the carbon cycle and therefore for the mitigation of global climate change. It has been proposed that NPP is limited by the availability of soil nutrients in lowland tropical forests and that belowground NPP decreases as edaphic fertility increases. This hypothesis was evaluated in two localities (Opogodó and Pacurita) of the Chocó Biogeographical region, one of the rainiest of the world, where the aboveground (litter and wood) and belowground (fine and coarse roots) components of NPP were measured. Fertility parameters (pH, nutrients, and texture) were also determined and related to NPP. Total NPP was similar between locations (23.7 vs. 24.2 t ha-1 year-1 for Opogodó and Pacurita, respectively). However, components of NPP showed differences: in Pacurita, with steeper topography, NPP of wood and coarse roots were higher; therefore, differences of topography and drainage between localities probably affected the NPP of wood. On the other hand, soils of Opogodó, where NPP of fine roots was higher, showed higher contents of sand, N+, and organic matter (OM). With the increase of pH, OM, N+, K, Mg, and sand, the NPP of leaves and fine roots as well as the percentage of NPP belowground also increased, which suggests NPP limitation by multiple nutrients. The increase of NPP belowground with the availability of edaphic nutrients evidenced a redistribution of the aboveground and belowground components of NPP with the increase of soil fertility in oligotrophic systems, probably as a mechanism to improve the capture of resources. PMID:28114418

Net Primary Productivity and Edaphic Fertility in Two Pluvial Tropical Forests in the Chocó Biogeographical Region of Colombia.

PubMed

Quinto-Mosquera, Harley; Moreno, Flavio

2017-01-01

The net primary productivity (NPP) of tropical forests is a key process of the carbon cycle and therefore for the mitigation of global climate change. It has been proposed that NPP is limited by the availability of soil nutrients in lowland tropical forests and that belowground NPP decreases as edaphic fertility increases. This hypothesis was evaluated in two localities (Opogodó and Pacurita) of the Chocó Biogeographical region, one of the rainiest of the world, where the aboveground (litter and wood) and belowground (fine and coarse roots) components of NPP were measured. Fertility parameters (pH, nutrients, and texture) were also determined and related to NPP. Total NPP was similar between locations (23.7 vs. 24.2 t ha-1 year-1 for Opogodó and Pacurita, respectively). However, components of NPP showed differences: in Pacurita, with steeper topography, NPP of wood and coarse roots were higher; therefore, differences of topography and drainage between localities probably affected the NPP of wood. On the other hand, soils of Opogodó, where NPP of fine roots was higher, showed higher contents of sand, N+, and organic matter (OM). With the increase of pH, OM, N+, K, Mg, and sand, the NPP of leaves and fine roots as well as the percentage of NPP belowground also increased, which suggests NPP limitation by multiple nutrients. The increase of NPP belowground with the availability of edaphic nutrients evidenced a redistribution of the aboveground and belowground components of NPP with the increase of soil fertility in oligotrophic systems, probably as a mechanism to improve the capture of resources.

Soil respiration patterns in root gaps 27 years after small scale experimental disturbance in Pinus contorta forests

NASA Astrophysics Data System (ADS)

Baker, S.; Berryman, E.; Hawbaker, T. J.; Ewers, B. E.

2015-12-01

While much attention has been focused on large scale forest disturbances such as fire, harvesting, drought and insect attacks, small scale forest disturbances that create gaps in forest canopies and below ground root and mycorrhizal networks may accumulate to impact regional scale carbon budgets. In a lodgepole pine (Pinus contorta) forest near Fox Park, WY, clusters of 15 and 30 trees were removed in 1988 to assess the effect of tree gap disturbance on fine root density and nitrogen transformation. Twenty seven years later the gaps remain with limited regeneration present only in the center of the 30 tree plots, beyond the influence of roots from adjacent intact trees. Soil respiration was measured in the summer of 2015 to assess the influence of these disturbances on carbon cycling in Pinus contorta forests. Positions at the centers of experimental disturbances were found to have the lowest respiration rates (mean 2.45 μmol C/m2/s, standard error 0.17 C/m2/s), control plots in the undisturbed forest were highest (mean 4.15 μmol C/m2/s, standard error 0.63 C/m2/s), and positions near the margin of the disturbance were intermediate (mean 3.7 μmol C/m2/s, standard error 0.34 C/m2/s). Fine root densities, soil nitrogen, and microclimate changes were also measured and played an important role in respiration rates of disturbed plots. This demonstrates that a long-term effect on carbon cycling occurs when gaps are created in the canopy and root network of lodgepole forests.

Root anatomy, morphology, and longevity among root orders in Vaccinium corymbosum (Ericaceae).

PubMed

Valenzuela-Estrada, Luis R; Vera-Caraballo, Vivianette; Ruth, Leah E; Eissenstat, David M

2008-12-01

Understanding root processes at the whole-plant or ecosystem scales requires an accounting of the range of functions within a root system. Studying root traits based on their branching order can be a powerful approach to understanding this complex system. The current study examined the highly branched root system of the ericoid plant, Vaccinium corymbosum L. (highbush blueberry) by classifying its root orders with a modified version of the morphometric approach similar to that used in hydrology for stream classification. Root anatomy provided valuable insight into variation in root function across orders. The more permanent portion of the root system occurred in 4th- and higher-order roots. Roots in these orders had radial growth; the lowest specific root length, N:C ratios, and mycorrhizal colonization; the highest tissue density and vessel number; and the coarsest root diameter. The ephemeral portion of the root system was mainly in the first three root orders. First- and 2nd-order roots were nearly anatomically identical, with similar mycorrhizal colonization and diameter, and also, despite being extremely fine, median lifespans were not very short (115-120 d; estimated with minirhizotrons). Our research underscores the value of examining root traits by root order and its implications to understanding belowground processes.

Root diversity in alpine plants: root length, tensile strength and plant age

NASA Astrophysics Data System (ADS)

Pohl, M.; Stroude, R.; Körner, C.; Buttler, A.; Rixen, C.

2009-04-01

A high diversity of plant species and functional groups is hypothesised to increase the diversity of root types and their subsequent effects for soil stability. However, even basic data on root characteristics of alpine plants are very scarce. Therefore, we determined important root characteristics of 13 plant species from different functional groups, i.e. grasses, herbs and shrubs. We excavated the whole root systems of 62 plants from a machine-graded ski slope at 2625 m a.s.l. and analysed the rooting depth, the horizontal root extension, root length and diameter. Single roots of plant species were tested for tensile strength. The age of herbs and shrubs was determined by growth-ring analysis. Root characteristics varied considerably between both plant species and functional groups. The rooting depth of different species ranged from 7.2 ± 0.97 cm to 20.5 ± 2.33 cm, but was significantly larger in the herb Geum reptans (70.8 ± 10.75 cm). The woody species Salix breviserrata reached the highest horizontal root extensions (96.8 ± 25.5 cm). Most plants had their longest roots in fine diameter classes (0.5

Thermochemical properties of flame gases from fine wildland fuels

Treesearch

Frank A. Albini

1979-01-01

Describes a theoretical model for calculating thermochemical properties of the gaseous fuel that burns in the free flame at the edge of a spreading fire in fine forest fuels. Predicted properties are the heat of combustion, stoichiometric air/fuel mass ratio, mass-averaged temperature, and mass fraction of unburned fuel in the gas mixture emitted from the flame-...

Soil incorporation of logging residue affects fine-root and mycorrhizal root-tip dynamics of young loblolly pine clones

Treesearch

Seth G. Pritchard; Chris A. Maier; Kurt H. Johnsen; Andrea J. Grabman; Anne P. Chalmers

2010-01-01

Loblolly pine (Pinus taeda L.) plantations cover a large geographic area of the southeastern USA and supply a large proportion of the nation’s wood products. Research on management strategies designed to maximize wood production while also optimizing nutrient use efficiency and soil C sequestration is needed. We used minirhizotrons to quantify the effects of...

Plant growth, biomass partitioning and soil carbon formation in response to altered lignin biosynthesis in Populus tremuloides.

PubMed

Hancock, Jessica E; Loya, Wendy M; Giardina, Christian P; Li, Laigeng; Chiang, Vincent L; Pregitzer, Kurt S

2007-01-01

We conducted a glasshouse mesocosm study that combined (13)C isotope techniques with wild-type and transgenic aspen (Populus tremuloides) in order to examine how altered lignin biosynthesis affects plant production and soil carbon formation. Our transgenic aspen lines expressed low stem lignin concentration but normal cellulose concentration, low lignin stem concentration with high cellulose concentration or an increased stem syringyl to guaiacyl lignin ratio. Large differences in stem lignin concentration observed across lines were not observed in leaves or fine roots. Nonetheless, low lignin lines accumulated 15-17% less root C and 33-43% less new soil C than the control line. Compared with the control line, transformed aspen expressing high syringyl lignin accumulated 30% less total plant C - a result of greatly reduced total leaf area - and 70% less new soil C. These findings suggest that altered stem lignin biosynthesis in Populus may have little effect on the chemistry of fine roots or leaves, but can still have large effects on plant growth, biomass partitioning and soil C formation.

Counting individual sulfur atoms in a protein by ultrahighresolution Fourier transform ion cyclotron resonance mass spectrometry: Experimental resolution of isotopic fine structure in proteins

PubMed Central

Shi, Stone D.-H.; Hendrickson, Christopher L.; Marshall, Alan G.

1998-01-01

A typical molecular ion mass spectrum consists of a sum of signals from species of various possible isotopic compositions. Only the monoisotopic peak (e.g., all carbons are 12C; all nitrogens are 14N, etc.) has a unique elemental composition. Every other isotope peak at approximately integer multiples of ∼1 Da higher in nominal mass represents a sum of contributions from isotope combinations differing by a few mDa (e.g., two 13C vs. two 15N vs. one 13C and one 15N vs. 34S, vs. 18O, etc., at ∼2 Da higher in mass than the monoisotopic mass). At sufficiently high mass resolving power, each of these nominal-mass peaks resolves into its isotopic fine structure. Here, we report resolution of the isotopic fine structure of proteins up to 15.8 kDa (isotopic 13C,15N doubly depleted tumor suppressor protein, p16), made possible by electrospray ionization followed by ultrahigh-resolution Fourier transform ion cyclotron resonance mass analysis at 9.4 tesla. Further, a resolving power of m/Δm50% ≈8,000,000 has been achieved on bovine ubiquitin (8.6 kDa). These results represent a 10-fold increase in the highest mass at which isotopic fine structure previously had been observed. Finally, because isotopic fine structure reveals elemental composition directly, it can be used to confirm or determine molecular formula. For p16, for example, we were able to determine (5.1 ± 0.3) the correct number (five) of sulfur atoms solely from the abundance ratio of the resolved 34S peak to the monoisotopic peak. PMID:9751700

Nano-scale mechanisms of metal rhizostabilization in mine tailings

NASA Astrophysics Data System (ADS)

Chorover, J.; Rushforth, R. R.; Hayes, S.; Root, R.; Maier, R.

2010-12-01

Desert mine tailings pose significant health risks to proximal communities and ecosystems because metal-laden particles in the un-vegetated landscapes are readily transported via wind and water erosion. Therefore, establishment of a bioactive, vegetated cover and associated root mass can contribute significantly to site remediation. As a result of delivery to the subsurface of labile forms of reduced carbon, the incipient rhizosphere presents a bioactive zone where geochemical disequilibria are strongly influenced by root-microbe-metal-mineral interactions. Infusion of biota and carbon affect local mineral transformations and the associated speciation of toxic metal(loid)s. We investigated biogeochemical transformations in Pb and Zn containing mine tailings from Klondyke State Superfund site (AZ) as affected by phytostabilization. The research approach was to combine instrumented column experiments with molecular spectroscopy of the solid phase. Pb LIII-edge and Zn K-edge EXAFS spectroscopy, synchrotron-based XRF and XRD, and Raman microspectroscopy were employed to assess local coordination and mineralogy of Pb and Zn. Prior to plant introduction, contaminant Pb in the weathered surficial tailings was dominantly present in the minerals plumbojarosite (PbFe6(SO4)4(OH)12) and PbSO4, whereas Zn was dominantly present as hemimorphite (Zn4Si2O7(OH)2.H2O), Zn phyllosilicate, and ZnSO4(s). Column experiments showed that planted columns diminished pore water and effluent concentrations of both Pb and Zn, whereas transport of some other metals (e.g., Cu) was enhanced by complexation with dissolved organic matter. Spectroscopic studies of fine root tissues and root-microbe-metal associations revealed the formation of apparently biogenic Mn oxide plaques that were highly enriched in Zn and Pb.

Quantifying Above‐ and Below‐ground Growth Responses of the Western Australian Oil Mallee, Eucalyptus kochii subsp. plenissima, to Contrasting Decapitation Regimes

PubMed Central

WILDY, DAN T.; PATE, JOHN S.

2002-01-01

Resprouting in the oil mallee, Eucalyptus kochii Maiden & Blakely subsp. plenissima Gardner (Brooker), involves generation of new shoots from preformed meristematic foci on the lignotuber. Numbers of such foci escalated from 200 per lignotuber in trees aged 1 year to 3000 on 4‐ to 5‐year‐old trees. Removal of shoot biomass by decapitation 5 cm above ground in summer (February) or spring (October) resulted in initiation of 140–170 new shoots, but approx. 400 shoots were induced to form if crops of new shoots were successively removed until sprouting ceased and rootstocks senesced. Initially, the new shoot biomass of regenerating coppices increased slowly and the root biomass failed to increase appreciably until 1·7–2·5 years after cutting. Newly cut trees showed loss of fine root biomass, and structural roots failed to secondarily thicken to the extent shown by uncut trees. After 2 years, the biomass of shoots of coppiced plants was only one‐third that of uncut control trees and shoot : root dry mass ratios of coppiced plants were still low (1·5–2·0) compared with those of the controls (average ratio of 3·1). Spring cutting promoted quicker and greater biomass recovery than summer cutting. Starch in below‐ground biomass fell quickly following decapitation and remained low for a 12–18 month period. Utilization of starch reserves in naturally regenerating coppices was estimated to provide only a small proportion of the dry matter accumulated in new shoots. Results are discussed in relation to their impact on coppicing ability of the species under natural conditions or when successively coppiced for shoot biomass production. PMID:12197516

Quantifying above- and below-ground growth responses of the western Australian oil mallee, Eucalyptus kochii subsp. plenissima, to contrasting decapitation regimes.

PubMed

Wildy, Dan T; Pate, John S

2002-08-01

Resprouting in the oil mallee, Eucalyptus kochii Maiden & Blakely subsp. plenissima Gardner (Brooker), involves generation of new shoots from preformed meristematic foci on the lignotuber. Numbers of such foci escalated from 200 per lignotuber in trees aged 1 year to 3,000 on 4- to 5-year-old trees. Removal of shoot biomass by decapitation 5 cm above ground in summer (February) or spring (October) resulted in initiation of 140-170 new shoots, but approx. 400 shoots were induced to form if crops of new shoots were successively removed until sprouting ceased and rootstocks senesced. Initially, the new shoot biomass of regenerating coppices increased slowly and the root biomass failed to increase appreciably until 1.7-2.5 years after cutting. Newly cut trees showed loss of fine root biomass, and structural roots failed to secondarily thicken to the extent shown by uncut trees. After 2 years, the biomass of shoots of coppiced plants was only one-third that of uncut control trees and shoot:root dry mass ratios of coppiced plants were still low (1.5-2.0) compared with those of the controls (average ratio of 3.1). Spring cutting promoted quicker and greater biomass recovery than summer cutting. Starch in below-ground biomass fell quickly following decapitation and remained low for a 12-18 month period. Utilization of starch reserves in naturally regenerating coppices was estimated to provide only a small proportion of the dry matter accumulated in new shoots. Results are discussed in relation to their impact on coppicing ability of the species under natural conditions or when successively coppiced for shoot biomass production.

Temporal changes of soil respiration under different tree species.

PubMed

Akburak, Serdar; Makineci, Ender

2013-04-01

Soil respiration rates were measured monthly (from April 2007 to March 2008) under four adjacent coniferous plantation sites [Oriental spruce (Picea orientalis L.), Austrian pine (Pinus nigra Arnold), Turkish fir (Abies bornmulleriana L.), and Scots pine (Pinus sylvestris L.)] and adjacent natural Sessile oak forest (Quercus petraea L.) in Belgrad Forest-Istanbul/Turkey. Also, soil moisture, soil temperature, and fine root biomass were determined to identify the underlying environmental variables among sites which are most likely causing differences in soil respiration. Mean annual soil moisture was determined to be between 6.3 % and 8.1 %, and mean annual temperature ranged from 13.0°C to 14.2°C under all species. Mean annual fine root biomass changed between 368.09 g/m(2) and 883.71 g/m(2) indicating significant differences among species. Except May 2007, monthly soil respiration rates show significantly difference among species. However, focusing on tree species, differences of mean annual respiration rates did not differ significantly. Mean annual soil respiration ranged from 0.56 to 1.09 g C/m(2)/day. The highest rates of soil respiration reached on autumn months and the lowest rates were determined on summer season. Soil temperature, soil moisture, and fine root biomass explain mean annual soil respiration rates at the highest under Austrian pine (R (2) = 0.562) and the lowest (R (2) = 0.223) under Turkish fir.

Complementarity in nutrient foraging strategies of absorptive fine roots and arbuscular mycorrhizal fungi across 14 coexisting subtropical tree species.

PubMed

Liu, Bitao; Li, Hongbo; Zhu, Biao; Koide, Roger T; Eissenstat, David M; Guo, Dali

2015-10-01

In most cases, both roots and mycorrhizal fungi are needed for plant nutrient foraging. Frequently, the colonization of roots by arbuscular mycorrhizal (AM) fungi seems to be greater in species with thick and sparsely branched roots than in species with thin and densely branched roots. Yet, whether a complementarity exists between roots and mycorrhizal fungi across these two types of root system remains unclear. We measured traits related to nutrient foraging (root morphology, architecture and proliferation, AM colonization and extramatrical hyphal length) across 14 coexisting AM subtropical tree species following root pruning and nutrient addition treatments. After root pruning, species with thinner roots showed more root growth, but lower mycorrhizal colonization, than species with thicker roots. Under multi-nutrient (NPK) addition, root growth increased, but mycorrhizal colonization decreased significantly, whereas no significant changes were found under nitrogen or phosphate additions. Moreover, root length proliferation was mainly achieved by altering root architecture, but not root morphology. Thin-root species seem to forage nutrients mainly via roots, whereas thick-root species rely more on mycorrhizal fungi. In addition, the reliance on mycorrhizal fungi was reduced by nutrient additions across all species. These findings highlight complementary strategies for nutrient foraging across coexisting species with contrasting root traits. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Analysis of hairy root culture of Rauvolfia serpentina using direct analysis in real time mass spectrometric technique.

PubMed

Madhusudanan, K P; Banerjee, Suchitra; Khanuja, Suman P S; Chattopadhyay, Sunil K

2008-06-01

The applicability of a new mass spectrometric technique, DART (direct analysis in real time) has been studied in the analysis of the hairy root culture of Rauvolfia serpentina. The intact hairy roots were analyzed by holding them in the gap between the DART source and the mass spectrometer for measurements. Two nitrogen-containing compounds, vomilenine and reserpine, were characterized from the analysis of the hairy roots almost instantaneously. The confirmation of the structures of the identified compounds was made through their accurate molecular formula determinations. This is the first report of the application of DART technique for the characterization of compounds that are expressed in the hairy root cultures of Rauvolfia serpentina. Moreover, this also constitutes the first report of expression of reserpine in the hairy root culture of Rauvolfia serpentina. Copyright (c) 2008 John Wiley & Sons, Ltd.

Fine root production and carbohydrate concentrations of mature longleaf pine (Pinus palustris P. Mill.) as affected by season of prescribed fire and drought

Treesearch

Mary Anne Sword Sayer; James D. Haywood

2005-01-01

The historical range of longleaf pine (Pinus palustris P. Mill) has been greatly reduced, in part, by lack of fire. Recently, the application of fire has become an accepted practice for the restoration of longleaf pine to former parts of its natural range. This study was designed to evaluate the effects of season of prescribed fire on the root growth...

Growth rates of rhizosphere microorganisms depend on competitive abilities of plants for nitrogen

NASA Astrophysics Data System (ADS)

Blagodatskaya, Evgenia; Littschwager, Johanna; Lauerer, Marianna; Kuzyakov, Yakov

2010-05-01

Rhizosphere - one of the most important ‘hot spots' in soil - is characterized not only by accelerated turnover of microbial biomass and nutrients but also by strong intra- and inter-specific competition. Intra-specific competition occurs between individual plants of the same species, while inter-specific competition can occur both at population level (plant species-specific, microbial species-specific interactions) and at community level (plant - microbial interactions). Such plant - microbial interactions are mainly governed by competition for available N sources, since N is one of the main growth limiting nutrients in natural ecosystems. Functional structure and activity of microbial community in rhizosphere is not uniform and is dependent on quantity and quality of root exudates which are plant specific. It is still unclear how microbial growth and turnover in the rhizosphere are dependent on the features and competitive abilities of plants for N. Depending on C and N availability, acceleration and even retardation of microbial activity and carbon mineralization can be expected in the rhizosphere of plants with high competitive abilities for N. We hypothesized slower microbial growth rates in the rhizosphere of plants with smaller roots, as they usually produce less exudates compared to plants with small shoot-to-root ratio. As the first hypothesis is based solely on C availability, we also expected the greater effect of N availability on microbial growth in rhizosphere of plants with smaller root mass. These hypothesis were tested for two plant species of strawberry: Fragaria vesca L. (native species), and Duchesnea indica (Andrews) Focke (an invasive plant in central Europe) growing in intraspecific and interspecific competition. Microbial biomass and the kinetic parameters of microbial growth in the rhizosphere were estimated by dynamics of CO2 emission from the soil amended with glucose and nutrients. Specific growth rate (µ) of soil microorganisms was estimated by fitting the parameters of the equation: CO2(t) = A + B × exp(µ×t), to the measured CO2 production rate (CO2(t)) after glucose addition, where A is the initial respiration rate uncoupled from ATP production, B the initial rate of the growing fraction of total respiration coupled with ATP generation and cell growth, and t time. Our study revealed the linkage between growth strategies of rhizosphere microorganisms and different adaptation strategies of F. vesca and D. indica to N limitation. Plant - strong competitor for N (D. indica) did not change root mass under N limitation causing the deficit of N in the rhizosphere and altering the structure of rhizosphere microbial community. Benefiting of slow growing microorganisms with K-strategy under N limiting conditions was indicated by strong decrease in specific microbial growth rates in the rhizosphere of D. indica. Root mass of the plant with weak competitive abilities for N (F. vesca) increased under lack of N to compensate the lack of nutrients. The increase in root mass and possible increase in amount of root exudates coincided with no structural changes in microbial community in rhizosphere of F. vesca. By intraspecific competition at low N level a 2.4-fold slower microbial specific growth rates were observed under D. indica (0.09 h-1) characterized by smaller root biomass and lower N content in roots compared with F. vesca. The generation time of actively growing microbial biomass was for the 6 hours longer in rhizosphere of D. indica than under F. vesca (10.7 to 4.6 h, respectively). Thus, under N limitation the strong competition for N between plant and microorganisms decreased microbial growth rates and carbon turnover in rhizosphere. By interspecific competition of both plants at low N level, microbial growth rates were similar to those for D. indica indicating that plant with stronger competitive abilities for N controls microbial community in the rhizosphere. At high N availability the root biomass did not differ significantly between both plants. This resulted in similar microbial growth rates for intra- and interspecific plant competition. Since high N level smoothed the differences between plant species in root and microbial biomass as well as in microbial growth rates, we conclude that competitive abilities of plant species were responsible for microbial growth in rhizosphere only under N imitation. As it is common that fine root proliferation and root exudation decrease at high N level, N addition smoothed the differences in microbial growth independently on plant competitive abilities.

Assessment of the temporal relationship between daily summertime ultra-fine particulate count concentration with PM2.5 and black carbon soot in Washington, DC

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

Allen, G.; Abt, E.; Koutrakis, P.

Several recent epidemiological studies have shown a significant relationship between ambient daily particulate mass concentrations and human health effects as measured by cardio-pulmonary morbidity and mortality. Much of the current research aimed at determining causal agents of these PM health effects focuses on fine mass (PM2.5), which is primarily the combustion-related component of PM10. Some studies have suggested that ultra-fine aerosols (typically defined as those particles that are less than 0.1 or 0.15 micrometers in diameter) may be an important category of particulate matter to consider, as opposed to or in addition to other measures of fine particle mass. Onemore » of the postulated toxicological mechanisms for ultra-fine particles is that it is the number of particles which is most important, and not necessarily their composition or mass. Some studies suggest that the count concentration could be important by overwhelming macrophages. Another possible particle metric that could be important in health-effect outcomes is particle surface area, which may serve as a condensation surface for gas phase components that are then deposited deep in the lung.« less

Light stops and fine-tuning in MSSM

NASA Astrophysics Data System (ADS)

Çiçi, Ali; Kırca, Zerrin; Ün, Cem Salih

2018-01-01

We discuss the fine-tuning issue within the MSSM framework. Following the idea that the fine-tuning can measure effects of some missing mechanism, we impose non-universal gaugino masses at the GUT scale, and explore the low scale implications. We realize that the fine-tuning parametrized with Δ _{EW} can be as low as zero. We consider the stop mass with a special importance and focus on the mass scales as m_{\\tilde{t}} ≤ 700 GeV, which are excluded by the current experiments when the stop decays into a neutralino along with a top quark or a chargino along with a bottom quark. We find that the stop mass can be as low as about 250 GeV with Δ _{EW} ˜ 50. We find that the solutions in this region can be exluded only up to 60% when stop decays into a neutralino-top quark, and 50% when it decays into a chargino-b quark. Setting 65% CL to be potential exclusion and 95% to be pure exclusion limit such solutions will be tested in near future experiments, which are conducted with higher luminosity. In addition to stop, the region with low fine-tuning and light stops predicts masses for the other supersymmetric particles such as m_{\\tilde{b}} ≳ 700 GeV, m_{\\tilde{τ }} ≳ 1 TeV, m_{\\tilde{χ }1^{± }} ≳ 120 GeV. The details for the mass scales and decay rates are also provided by tables of benchmark points.

Cytological and ultrastructural studies on root tissues

NASA Technical Reports Server (NTRS)

Slocum, R. D.; Gaynor, J. J.; Galston, A. W.

1984-01-01

The anatomy and fine structure of roots from oat and mung bean seedlings, grown under microgravity conditions for 8 days aboard the Space Shuttle, was examined and compared to that of roots from ground control plants grown under similar conditions. Roots from both sets of oat seedlings exhibited characteristic monocotyledonous tissue organization and normal ultrastructural features, except for cortex cell mitochondria, which exhibited a 'swollen' morphology. Various stages of cell division were observed in the meristematic tissues of oat roots. Ground control and flight-grown mung bean roots also showed normal tissue organization, but root cap cells in the flight-grown roots were collapsed and degraded in appearance, especially at the cap periphery. At the ultrastructural level, these cells exhibited a loss of organelle integrity and a highly-condensed cytoplasm. This latter observation perhaps suggests a differing tissue sensitivity for the two species to growth conditions employed in space flight. The basis for abnormal root cap cell development is not understood, but the loss of these putative gravity-sensing cells holds potential significance for long term plant growth orientation during space flight.

Root and stem partitioning of Pinus taeda

Treesearch

Timothy J. Albaugh; H. Lee Allen; Lance W. Kress

2006-01-01

We measured root and stem mass at three sites (Piedmont (P), Coastal Plain (C), and Sandhills (S)) in the southeastern United States. Stand density, soil texture and drainage, genetic makeup and environmental conditions varied with site while differences in tree size at each site were induced with fertilizer additions. Across sites, root mass was about one half of stem...

Carbon transfer from photosynthesis to below ground fine root/hyphae respiration in Quercus serrata using stable carbon isotope pulse labeling

NASA Astrophysics Data System (ADS)

Dannoura, M.; Kominami, Y.; Takanashi, S.; Takahashi, K.

2013-12-01

Studying carbon allocation in trees is a key to better understand belowground carbon cycle and its response to climate change. Tracing 13C in tree and soil compartments after pulse labeling is one of powerful tool to study the fate of carbon in forest ecosystems. This experiment was conducted in Yamashiro experimental forest, Kyoto, Japan. Annual mean temperature and precipitation from 1994 to 2009 are 15.5 ° C and 1,388 mm respectively. The branch pulse labeling were done 7 times in 2011 using same branch of Quercus serrata (H:11.7 m, DBH; 33.7 cm) to see seasonal variations of carbon velocity. Whole crown labeling of Quercus serrata (H:9 m, DBH; 13.7 cm) was done in 2012 to study carbon allocation and to especially focus on belowground carbon flux until to the hyphae respiration. Pure 13CO2 (99.9%) was injected to the labeling chamber which was set to branch or crown. Then, after one hour of branch labeling and 3.5 hour for crown labeling, the chamber was opened. Trunk respiration chambers, fine root chambers and hyphae chambers were set to the target tree to trace labeled carbon in the CO2 efflux. 41 μm mesh was used to exclude ingrowth of roots into hyphae chambers. The results show that the velocity of carbon through the tree varied seasonally, with higher velocity in summer than autumn, averaging 0.47 m h-1. Half-lives of labeled carbon in autotrophic respiration were similar above and below ground during the growing season, but they were twice longer in trunk than in root in autumn. From the whole crown labeling done end of growing season, the 13CO2 signal was observed 25 hours after labeling in trunk chamber and 34-37.7 hours after labeling in fine root and hyphae respiration almost simultaneously. Half-lives of 13 was longer in trunk than below ground. Trunk respiration was still using labelled carbon during winter suggesting that winter trunk respiration is partly fueled by carbon stored in the trunk at the end of the growing season.

40 CFR 430.117 - Pretreatment standards for new sources (PSNS).

Code of Federal Regulations, 2010 CFR

2010-07-01

... using these biocides: Subpart K [PSNS for non-integrated mills where fine paper is produced from... equivalent mass limitations are provided as guidance in cases when POTWs find it necessary to impose mass effluent limitations. Subpart K [PSNS for non-integrated mills where fine paper is produced from purchased...

40 CFR 430.117 - Pretreatment standards for new sources (PSNS).

Code of Federal Regulations, 2011 CFR

2011-07-01

... using these biocides: Subpart K [PSNS for non-integrated mills where fine paper is produced from... equivalent mass limitations are provided as guidance in cases when POTWs find it necessary to impose mass effluent limitations. Subpart K [PSNS for non-integrated mills where fine paper is produced from purchased...

40 CFR 430.117 - Pretreatment standards for new sources (PSNS).

Code of Federal Regulations, 2014 CFR

2014-07-01

... using these biocides: Subpart K [PSNS for non-integrated mills where fine paper is produced from... equivalent mass limitations are provided as guidance in cases when POTWs find it necessary to impose mass effluent limitations. Subpart K [PSNS for non-integrated mills where fine paper is produced from purchased...

40 CFR 430.117 - Pretreatment standards for new sources (PSNS).

Code of Federal Regulations, 2012 CFR

2012-07-01

... using these biocides: Subpart K [PSNS for non-integrated mills where fine paper is produced from... equivalent mass limitations are provided as guidance in cases when POTWs find it necessary to impose mass effluent limitations. Subpart K [PSNS for non-integrated mills where fine paper is produced from purchased...

Cloning and characterization of phenylalanine ammonia-lyase and cinnamate 4-hydroxylase and pyranocoumarin biosynthesis in Angelica gigas.

PubMed

Park, Jee Hee; Park, Nam Il; Xu, Hui; Park, Sang Un

2010-08-27

Phenylalanine ammonia-lyase (PAL) and cinnamate 4-hydroxylase (C4H) are important enzymes in the phenylpropanoid pathway and also in the accumulation of decursin (1) and decursinol angelate (2), which are major secondary metabolites in Angelica gigas. Using PCR with degenerate primers targeted to conserved regions of available orthologous PAL and C4H sequences, cDNAs encoding PAL and C4H from A. gigas were isolated. Both genes were used to show the comparative developmental and inducible accumulation of mRNAs in different organs and in suspension cells of A. gigas. PAL and C4H were induced most strongly in response to 300 microM methyl jasmonate treatment at 6 and 12 h, respectively, and were highly expressed in the fine roots of A. gigas. Similarly, the production of 1 and 2 was most prolific in the fine roots of the plant.

Seedling root targets

Treesearch

Diane L. Haase

2011-01-01

Roots are critical to seedling performance after outplanting. Although root quality is not as quick and simple to measure as shoot quality, target root characteristics should be included in any seedling quality assessment program. This paper provides a brief review of root characteristics most commonly targeted for operational seedling production. These are: root mass...

Sources of atmospheric aerosol from long-term measurements (5 years) of chemical composition in Athens, Greece.

PubMed

Paraskevopoulou, D; Liakakou, E; Gerasopoulos, E; Mihalopoulos, N

2015-09-15

To identify the sources of aerosols in Greater Athens Area (GAA), a total of 1510 daily samples of fine (PM 2.5) and coarse (PM 10-2,5) aerosols were collected at a suburban site (Penteli), during a five year period (May 2008-April 2013) corresponding to the period before and during the financial crisis. In addition, aerosol sampling was also conducted in parallel at an urban site (Thissio), during specific, short-term campaigns during all seasons. In all these samples mass and chemical composition measurements were performed, the latest only at the fine fraction. Particulate organic matter (POM) and ionic masses (IM) are the main contributors of aerosol mass, equally contributing by accounting for about 24% of the fine aerosol mass. In the IM, nss-SO4(-2) is the prevailing specie followed by NO3(-) and NH4(+) and shows a decreasing trend during the 2008-2013 period similar to that observed for PM masses. The contribution of water in fine aerosol is equally significant (21 ± 2%), while during dust transport, the contribution of dust increases from 7 ± 2% to 31 ± 9%. Source apportionment (PCA and PMF) and mass closure exercises identified the presence of six sources of fine aerosols: secondary photochemistry, primary combustion, soil, biomass burning, sea salt and traffic. Finally, from winter 2012 to winter 2013 the contribution of POM to the urban aerosol mass is increased by almost 30%, reflecting the impact of wood combustion (dominant fuel for domestic heating) to air quality in Athens, which massively started in winter 2013. Copyright © 2015 Elsevier B.V. All rights reserved.

Assessing the potential for rhizoremediation of PCB contaminated soils in northern regions using native species

PubMed Central

Slater, Heather; Gouin, Todd; Leigh, Mary Beth

2011-01-01

Rhizosphere bioremediation of polychlorinated biphenyls (PCBs) offers a potentially inexpensive approach to remediating contaminated soils that is particularly attractive in remote regions including the Arctic. We assessed the abilities of two tree species native to Alaska, Salix alaxensis (felt-leaf willow) and Picea glauca (white spruce), to promote microbial biodegradation of PCBs via the release of phytochemicals upon fine root death. Crushed fine roots, biphenyl (PCB analogue) or salicylate (willow secondary compound) were added to microcosms containing soil spiked with PCBs and resultant PCB disappearance, soil toxicity and microbial community changes were examined. After 180 d, soil treated with willow root crushates showed a significantly greater PCB loss than untreated soils for some PCB congeners, including the toxic congeners, PCB 77, 105 and 169, and showed a similar PCB loss pattern (in both extent of degradation and congeners degraded) to biphenyl-treated microcosms. Neither P. glauca (white spruce) roots nor salicylate enhanced PCB loss, indicating that biostimulation is plant species specific and was not mediated by salicylate. Soil toxicity assessed using the Microtox bioassay indicated that the willow treatment resulted in a less toxic soil environment. Molecular microbial community analyses indicated that biphenyl and salicylate promoted shifts in microbial community structure and composition that differed distinctly from each other and from the crushed root treatments. The biphenyl utilizing bacterium, Cupriavidus spp. was isolated from the soil. The findings suggest that S. alaxensis may be an effective plant for rhizoremediation by altering microbial community structure, enhancing the loss of some PCB congeners and reducing the toxicity of the soil environment. PMID:21596420

Influence of sewage sludge, as a substrate, in the plasticity of functional characteristics of plants.

PubMed

da Silva, Vicente Elício Porfiro Sales Gonçalves; Buarque, Patrícia Marques Carneiro; Ferreira, Wanessa Nepomuceno; Buarque, Hugo Leonardo de Brito; Silva, Maria Amanda Menezes

2018-04-24

This work aimed to evaluate the effect of sewage sludge application as fertilizer on the plasticity of functional characteristics of species commonly found in the Caatinga. The research was developed in the nursery of the Federal Institute of Education, Science and Technology of Ceará (IFCE), Quixadá campus, located in northeastern Brazil. Three treatments were applied: raw sludge, sanitized sludge, and no manipulation. In each treatment, five species were planted, each with five individuals, totaling 75 individuals, which were tagged, and 4 months after germination, they were destroyed to obtain dry matter content (TMSF) from leaf, stem (TMSC), fine root (TMSRF), and thick root (TMSRG); leaf area; height and diameter of the seedling; and length above and below the ground. The sanitized sludge was responsible for giving higher values for leaf area, height of the seedlings, and diameter and length of stem and root. However, the dry matter content of the fine roots was higher in the treatment without manipulation. At the community level, as TMSRG increased, TMSC also increased, the same occurred between TMSRG and TMSRF, TMSC and TMSRF, and stem length and leaf area. In the treatment without manipulation, there was a positive correlation between leaf area, height and plant diameter, and negative correlation between root length and plant diameter. Thus, it can be concluded that the use of sanitized sludge is a good tool to increase the availability of soil resources, conferring to individuals' greater dry matter content, greater leaf area, and higher height and diameter above the ground.

Shifts and disruptions in resource-use trait syndromes during the evolution of herbaceous crops.

PubMed

Milla, Rubén; Morente-López, Javier; Alonso-Rodrigo, J Miguel; Martín-Robles, Nieves; Chapin, F Stuart

2014-10-22

Trait-based ecology predicts that evolution in high-resource agricultural environments should select for suites of traits that enable fast resource acquisition and rapid canopy closure. However, crop breeding targets specific agronomic attributes rather than broad trait syndromes. Breeding for specific traits, together with evolution in high-resource environments, might lead to reduced phenotypic integration, according to predictions from the ecological literature. We provide the first comprehensive test of these hypotheses, based on a trait-screening programme of 30 herbaceous crops and their wild progenitors. During crop evolution plants became larger, which enabled them to compete more effectively for light, but they had poorly integrated phenotypes. In a subset of six herbaceous crop species investigated in greater depth, competitiveness for light increased during early plant domestication, whereas diminished phenotypic integration occurred later during crop improvement. Mass-specific leaf and root traits relevant to resource-use strategies (e.g. specific leaf area or tissue density of fine roots) changed during crop evolution, but in diverse and contrasting directions and magnitudes, depending on the crop species. Reductions in phenotypic integration and overinvestment in traits involved in competition for light may affect the chances of upgrading modern herbaceous crops to face current climatic and food security challenges. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Isolation and characterization of N2 -fixing bacteria from giant reed and switchgrass for plant growth promotion and nutrient uptake.

PubMed

Xu, Jia; Kloepper, Joseph W; Huang, Ping; McInroy, John A; Hu, Chia H

2018-05-01

The aims of this study were to isolate and characterize N 2 -fixing bacteria from giant reed and switchgrass and evaluate their plant growth promotion and nutrient uptake potential for use as biofertilizers. A total of 190 bacteria were obtained from rhizosphere soil and inside stems and roots of giant reed and switchgrass. All the isolates were confirmed to have nitrogenase activity, 96.9% produced auxin, and 85% produced siderophores. Then the top six strains, including Sphingomonas trueperi NNA-14, Sphingomonas trueperi NNA-19, Sphingomonas trueperi NNA-17, Sphingomonas trueperi NNA-20, Psychrobacillus psychrodurans NP-3, and Enterobacter oryzae NXU-38, based on nitrogenase activity, were inoculated on maize and wheat seeds in greenhouse tests to assess their potential benefits to plants. All the selected strains promoted plant growth by increasing at least one plant growth parameter or increasing the nutrient concentration of maize or wheat plants. NNA-14 outperformed others in promoting early growth and nutrient uptake by maize. Specifically, NNA-14 significantly increased root length, surface area, and fine roots of maize by 14%, 12%, and 17%, respectively, and enhanced N, Ca, S, B, Cu, and Zn in maize. NNA-19 and NXU-38 outperformed others in promoting both early growth and nutrient uptake by wheat. Specifically, NNA-19 significantly increased root dry weight and number of root tips of wheat by 25% and 96%, respectively, and enhanced Ca in wheat. NXU-38 significantly increased root length, surface area, and fine roots of wheat by 21%, 13%, and 26%, respectively, and enhanced levels of Ca and Mg in wheat. It is concluded that switchgrass and giant reed are colonized by N 2 -fixing bacteria that have the potential to contribute to plant growth and nutrient uptake by agricultural crops. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

ZIFL1.1 transporter modulates polar auxin transport by stabilizing membrane abundance of multiple PINs in Arabidopsis root tip

PubMed Central

Remy, Estelle; Baster, Pawel; Friml, Jiří; Duque, Paula

2013-01-01

Cell-to-cell directional flow of the phytohormone auxin is primarily established by polar localization of the PIN auxin transporters, a process tightly regulated at multiple levels by auxin itself. We recently reported that, in the context of strong auxin flows, activity of the vacuolar ZIFL1.1 transporter is required for fine-tuning of polar auxin transport rates in the Arabidopsis root. In particular, ZIFL1.1 function protects plasma-membrane stability of the PIN2 carrier in epidermal root tip cells under conditions normally triggering PIN2 degradation. Here, we show that ZIFL1.1 activity at the root tip also promotes PIN1 plasma-membrane abundance in central cylinder cells, thus supporting the notion that ZIFL1.1 acts as a general positive modulator of polar auxin transport in roots. PMID:23857365

Drought-induced changes in root biomass largely result from altered root morphological traits: evidence from a synthesis of global field trials.

PubMed

Zhou, Guiyao; Zhou, Xuhui; Nie, Yuanyuan; Bai, Shahla Hosseini; Zhou, Lingyan; Shao, Junjiong; Cheng, Weisong; Wang, Jiawei; Hu, Fengqin; Fu, Yuling

2018-06-07

Extreme drought is likely to become more frequent and intense as a result of global climate change, which may significantly impact plant root traits and responses (i.e., morphology, production, turnover, and biomass). However, a comprehensive understanding of how drought affects root traits and responses remains elusive. Here, we synthesized data from 128 published studies under field conditions to examine the responses of 17 variables associated with root traits to drought. Our results showed that drought significantly decreased root length and root length density by 38.29% and 11.12%, respectively, but increased root diameter by 3.49%. However, drought significantly increased root: shoot mass ratio and root cortical aerenchyma by 13.54% and 90.7%, respectively. Our results suggest that drought significantly modified root morphological traits and increased root mortality, and the drought-induced decrease in root biomass was less than shoot biomass, causing higher root: shoot mass ratio. The cascading effects of drought on root traits and responses may need to be incorporated into terrestrial biosphere models to improve prediction of the climate-biosphere feedback. This article is protected by copyright. All rights reserved.

The Role of Fine Sediment Content on Soil Consolidation and Debris Flows Development after Earthquake

NASA Astrophysics Data System (ADS)

Lyu, L.; Xu, M., III; Wang, Z.

2017-12-01

Fine sediment has been identified as an important factor determining the critical runoff that initiates debris flows because its contribution to shear strength through consolidation. Especially, owing to the 2008 Wenchuan earthquake in China enormous of loose sediment with different fractions of fine particles was eroded and supplied as materials for debris flows. The loose materials are gradually consolidated along with time, and therefore stronger rainfall is required to overcome the shear strength and to initiate debris flows. In this study, flume experiments were performed to explore soil consolidation and shear strength on mass failure and debris flow initiation under the conditions that different fractions of fine sediment were contained in the materials. Under the low content of fine sediment conditions (mass percentages: 0-10%), the debris flows formed with large pores and low shear strength and thus fine particles were too few to fill up the pores among the coarse particles. The consolidation rate was mostly influenced by the content of the fine particles. Consolidation of fine particles caused an increase of the shear strength and decrease of the rainfall infiltration, and therefore, debris flow initiation required stronger rainfall as the consolidation of the fine particles developed.

Biogeomorphological influence of slope processes and sedimentology on vascular talus vegetation in the southern Cascades, California

NASA Astrophysics Data System (ADS)

Pérez, Francisco L.

2012-02-01

The vascular vegetation of alpine talus slopes between 2035 and 3095 m altitude was studied at Lassen Volcanic National Park (California) in the Cascade Range. Taluses show a diverse flora, with 79 plant species; growth forms include coniferous trees, shrubs, suffrutices, herbs, graminoids, and ferns. Spatial patterns of plant distribution were studied along 40 point-intercept transects. Plant cover was low (0-32.7%) on all slopes, spatially variable, and showed no consistent trends. Sedimentological characteristics were determined by photosieving next to 1500 plants; this census indicated preferential plant growth on blocks and cobbles, with 43.2% and 23.3% of the plants growing on these stones, respectively; fewer specimens were rooted on pebbles (13%) or on stone-free gravel areas (20.5%). Growth forms displayed different substrate preferences: 92.5% of the shrubs and 83% of the suffrutices colonized blocks or cobbles, but only 57.2% of the herbs and 59.8% of the graminoids grew on large stones. Plants are associated with large clasts because (1) coarse talus is more stable than fine sediment areas, which are more frequently disturbed by various geomorphic processes, and (2) large stones help conserve substrate water beneath them while moisture quickly evaporates from fine debris. Root patterns were studied for 30 plant species; 10 specimens for each species were excavated and inspected, and several root growth ratios calculated. All species exhibited pronounced root asymmetry, as roots for most plants grew upslope from their shoot base. For 23 species, all specimens had 100% of their roots growing upslope; for the other 7 species, 92.2-99.3% of below-ground biomass extended uphill. This uneven root distribution is ascribed to continual substrate instability and resulting talus shift; as cascading debris progressively buries roots and stems, plants are gradually pushed and/or stretched downhill. Various disturbance events affect root development. Slope erosion following rubble removal often exposes plant roots. Debris deposition can completely bury plants; some may survive sedimentation, producing new shoots that grow through accumulated debris. Shrubs may propagate by layering, as adventitious roots develop along buried stems; or produce new clones along their roots. Slope processes may damage and transport plant pieces downhill; some species can sprout from severed, displaced root or stem fragments. Vegetation interacts with several geomorphic processes, including debris flows, grain flows, rockfall, snow avalanches, frost creep, and runoff. Larger plants may alter local patterns of debris movement and deposition, damming cascading debris on their upslope side and deflecting sediments laterally to plant margins, where they form narrow elongated stone stripes.

Does mycorrhizal inoculation benefit plant survival, plant development and small-scale soil fixation? Results from a perennial eco-engineering field experiment in the Swiss Alps.

NASA Astrophysics Data System (ADS)

Bast, Alexander; Grimm, Maria; Graf, Frank; Baumhauer, Roland; Gärtner, Holger

2015-04-01

In mountain environments superficial slope failures on coarse grained, vegetation-free slopes are common processes and entail a certain risk for humans and socio-economic structures. Eco-engineering measures can be applied to mitigate slope instabilities. In this regard, limited plant survival and growth can be supported by mycorrhizal inoculation, which was successfully tested in laboratory studies. However, related studies on a field scale are lacking. Furthermore, mycorrhizae are known to enhance soil aggregation, which is linked to soil physics such as shear strength, and hence it is a useful indicator for near-surface soil/slope stability. The overall objective of our contribution was to test whether mycorrhizal inoculation can be used to promote eco-engineering measures in steep alpine environments based on a five-year field experiment. We hypothesized that mycorrhizal inoculation (i) enhances soil aggregation, (ii) stimulate plant survival and fine root development, (iii) effects plant performance, (iv) the stimulated root development in turn influences aggregate stability, and (v) that climatic variations play a major role in fine-root development. We established mycorrhizal and non-mycorrhizal treated eco-engineered research plots (hedge layers mainly consisting of Alnus spp. and Salix spp.) on a field experimental scale. The experimental site is in the eastern Swiss Alps at an erosion-prone slope where many environmental conditions can be seen as homogeneous. Soil aggregation, fine root development and plant survival was quantified at the end of four growing seasons (2010, '11, '12, '14). Additionally, growth properties of Alnus spp. and Salix spp. were measured and their biomass estimated. Meteorological conditions, soil temperature and soil water content were recorded. (i) The introduced eco-engineering measures enhanced aggregate stability significantly. In contrast to published greenhouse and laboratory studies, mycorrhizal inoculation delayed soil aggregate stabilization relative to the non-inoculated site but resulted in a significantly higher aggregate stability compared to the control and the non-inoculated site at the end of the third growing season. (ii) Plant survival was significantly improved by the inoculation. Fine-root development was stimulated but not immediately. At the end of the third growing season, root length density tended to be higher and mean root diameter was significantly increased at the mycorrhizal treated site. (iii) Analyses on plant performance of Alnus and Salix demonstrated that the inoculated saplings achieved significantly higher survival rates. There was no treatment effect on plant growth properties except in 2010, where plant height and main stem diameter of Alnus was increased at the mycorrhizal treated site. The estimated total biomass of Alnus and Salix was higher at the mycorrhizal treated site. (iv) There was a positive correlation between root length density and aggregate stability, whereas roots < 0.5 mm were most influential on aggregate stability. (v) Interannual climatic variations seem to have a crucial influence on root development and, hence, on slope stability. There is a temporal offset of two growing seasons between inoculation effects tested in greenhouse/laboratory and the presented field experiment. However, the application of a commercial mycorrhizal inoculum in eco-engineering measures is a beneficial promoter to mitigate slope instability and surface erosion but needs to be tested at other sites. The contribution is mainly based on Bast (2014) and was funded by the Wolfermann Nägeli Stiftung Zürich and the Swiss Federal Office for Environment (BAFU No.: 09.0027.PJ/I211-3446). Bast, A. (2014): Mycorrhizal inoculation as a promoter for sustainable eco-engineering measures in steep alpine environments? Results of a three-year field experiment in the Arieschbach catchment, Fideris, eastern Swiss Alps. PhD Thesis. University of Berne: 149pp.

Effects of Construction of the Digital Multipurpose Range Complex (DMPRC) on Riparian and Stream Ecosystems at Fort Benning, Georgia. Addendum

DTIC Science & Technology

2009-06-01

root dynamics in riparian forests. Soil Science Society of America 69(3):729-737. Houser, J. N., P. J. Mulholland, and K. O. Maloney. 2006. Upland...Forested Wetlands, D. M. Amatya and J. Nettles (eds). New Bern, NC. American Society of Agricultural and Biological Engineers, St. Joseph, MI...primary productivity, vegetation composition, structure, and fine root dynamics in riparian forests. Kelly O. Maloney, Ph.D. in Biological Sciences

Metastatic squamous cell carcinoma of the gingiva appearing as a solitary branchial cyst carcinoma: diagnostic role of PET/CT.

PubMed

Zhang, Xiong-Xin; Zhao, Kui; Zhou, Shui-Hong; Wang, Qin-Ying; Liu, Jian-Hua; Lu, Zhong-Jie

2014-01-01

We herein present a case of a left cervical cystic mass, for which the initial pathological diagnosis was branchial cleft cyst carcinoma (following complete mass excision). Thorough postoperative examinations, including with FDG positron emission tomography/computed tomography (PET/CT), revealed a primary tumor in the retromolar region of the left mandible. A 52-year-old female presented with a 2-month history of a painless, progressively enlarged left-sided neck mass. Fine-needle aspiration biopsy suggested a branchial cleft cyst. Physical examination revealed a 3 × 3-cm smooth, tender mass in the upper-left neck and anterior border of the sternocleidomastoid muscle. Examination using nasendoscopy and a strobolaryngoscope revealed no abnormalities of the nasal cavity, nasopharynx, oropharynx, hypopharynx or larynx. MRI of the neck revealed a solitary, round, cystic mass under the left parotid gland. The mass was excised completely. Pathologic results indicated a branchial cleft cyst carcinoma. According to the diagnostic criteria for a branchial cleft cystic carcinoma, PET/CT was performed to detect the occult primary site. PET/CT revealed high FDG uptake in the tooth root of the left mandible. Frozen sections of the mass were indicative of moderate, differentiated squamous cell carcinoma. The carcinoma in the retromolar region of the left mandible was locally excised under general anesthesia. A partial left maxillectomy, partial mandibulectomy, and left radical neck dissection were performed. The patient received postoperative concurrent chemoradiotherapy, and was disease-free at the 8-month follow-up. True branchial cleft cyst carcinoma is rare: once diagnosed, it should be distinguished from metastatic cystic cervical lymph and occult primary carcinoma. FDG PET/CT is useful in the identification of occult primary tumor.

Coarse and fine aerosol source apportionment in Rio de Janeiro, Brazil

NASA Astrophysics Data System (ADS)

Godoy, Maria Luiza D. P.; Godoy, José Marcus; Roldão, Luiz Alfredo; Soluri, Daniela S.; Donagemma, Raquel A.

The metropolitan area of Rio de Janeiro is one of the twenty biggest urban agglomerations in the world, with 11 million inhabitants in the metropolitan area, and has a high population density, with 1700 hab. km -2. For this aerosol source apportionment study, the atmospheric aerosol sampling was performed at ten sites distributed in different locations of the metropolitan area from September/2003 to December/2005, with sampling during 24 h on a weekly basis. Stacked filter units (SFU) were used to collect fine and coarse aerosol particles with a flow rate of 17 L min -1. In both size fractions trace elements were analyzed by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) as well as water-soluble species by Ion-Chromatography (IC). Also gravimetric analysis and reflectance measurements provided aerosol mass and black carbon concentrations. Very good detection limits for up to 42 species were obtained. Mean annual PM 10 mass concentration ranged from 20 to 37 μg m -3, values that are within the Brazilian air quality standards. Receptor models such as principal factor analysis, cluster analysis and absolute principal factor analysis were applied in order to identify and quantify the aerosol sources. For fine and coarse modes, circa of 100% of the measured mass was quantitatively apportioned to relatively few identified aerosol sources. A very similar and consistent source apportionment was obtained for both fine and coarse modes for all 10 sampling sites. Soil dust is an important component, accounting for 22-72% and for 25-48% of the coarse and fine mass respectively. On the other hand, anthropogenic sources as vehicle traffic and oil combustion represent a relatively high contribution (52-75%) of the fine aerosol mass. The joint use of ICP-MS and IC analysis of species in aerosols has proven to be reliable and feasible for the analysis of large amount of samples, and the coupling with receptor models provided an excellent method for quantitative aerosol source apportionment in large urban areas.

Spatial and monthly trends in speciated fine particle concentration in the United States

NASA Astrophysics Data System (ADS)

Malm, William C.; Schichtel, Bret A.; Pitchford, Marc L.; Ashbaugh, Lowell L.; Eldred, Robert A.

2004-02-01

In the spring of 1985 an interagency consortium of federal land management agencies and the Environmental Protection Agency established the Interagency Monitoring of Protected Visual Environments (IMPROVE) network to assess visibility and aerosol monitoring for the purpose of tracking spatial and temporal trends of visibility and visibility-impairing particles in rural areas. The program was initiated with 20 monitoring sites and was expanded to 165 sites between 2000 and 2003. This paper reports on fine aerosol data collected in the year 2001 at 143 sites. The major fine (dp < 2.5 μm) particle aerosol species, sulfates, nitrates, organics, light-absorbing carbon, and wind-blown dust, and coarse gravimetric mass are monitored, and at some sites, light scattering and/or extinction are measured. Sulfates, carbon, and crustal material are responsible for most of the fine mass at the majority of locations throughout the United States, while at sites in southern California and the midwestern United States, nitrates can contribute significantly. In the eastern United States, sulfates contribute between 50 and 60% of the fine mass. Sulfate concentrations tend to be highest in the summer months while organic concentrations can be high in the spring, summer, or fall seasons, depending upon fire-related emissions. However, at the two urban sites, Phoenix, Arizona, and Puget Sound, Washington, organics peak during the winter months. Nitrate concentrations also tend to be highest during the winter months. During the spring months in many areas of the western United States, fine soil can contribute as much as 40% of fine mass. The temporal changes in soil concentration that occur simultaneously over much of the western United States including the Rocky Mountain region suggest a large source region, possibly long-range transport of Asian dust.

Size distribution of chemical elements and their source apportionment in ambient coarse, fine, and ultrafine particles in Shanghai urban summer atmosphere.

PubMed

Lü, Senlin; Zhang, Rui; Yao, Zhenkun; Yi, Fei; Ren, Jingjing; Wu, Minghong; Feng, Man; Wang, Qingyue

2012-01-01

Ambient coarse particles (diameter 1.8-10 microm), fine particles (diameter 0.1-1.8 microm), and ultrafine particles (diameter < 0.1 microm) in the atmosphere of the city of Shanghai were sampled during the summer of 2008 (from Aug 27 to Sep 08). Microscopic characterization of the particles was investigated by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDX). Mass concentrations of Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Br, Rb, Sr, and Pb in the size-resolved particles were quantified by using synchrotron radiation X-ray fluorescence (SRXRF). Source apportionment of the chemical elements was analyzed by means of an enrichment factor method. Our results showed that the average mass concentrations of coarse particles, fine particles and ultrafine particles in the summer air were 9.38 +/- 2.18, 8.82 +/- 3.52, and 2.02 +/- 0.41 microg/m3, respectively. The mass percentage of the fine particles accounted for 51.47% in the total mass of PM10, indicating that fine particles are the major component in the Shanghai ambient particles. SEM/EDX results showed that the coarse particles were dominated by minerals, fine particles by soot aggregates and fly ashes, and ultrafine particles by soot particles and unidentified particles. SRXRF results demonstrated that crustal elements were mainly distributed in the coarse particles, while heavy metals were in higher proportions in the fine particles. Source apportionment revealed that Si, K, Ca, Fe, Mn, Rb, and Sr were from crustal sources, and S, Cl, Cu, Zn, As, Se, Br, and Pb from anthropogenic sources. Levels of P, V, Cr, and Ni in particles might be contributed from multi-sources, and need further investigation.

Modulation of statolith mass and grouping in white clover (Trifolium repens) growth in 1-g, microgravity and on the clinostat

NASA Technical Reports Server (NTRS)

Smith, J. D.; Todd, P.; Staehelin, L. A.

1997-01-01

Current models of gravity perception in higher plants focus on the buoyant weight of starch-filled amyloplasts as the initial gravity signal susceptor (statolith). However, no tests have yet determined if statolith mass is regulated to increase or decrease gravity stimulus to the plant. To this end, the root caps of white clover (Trifolium repens) grown in three gravity environments with three different levels of gravity stimulation have been examined: (i) 1-g control with normal static gravistimulation, (ii) on a slow clinostat with constant gravistimulation, and (iii) in the stimulus-free microgravity aboard the Space Shuttle. Seedlings were germinated and grown in the BioServe Fluid Processing Apparatus and root cap structure was examined at both light and electron microscopic levels, including three-dimensional cell reconstruction from serial sections. Quantitative analysis of the electron micrographs demonstrated that the starch content of amyloplasts varied with seedling age but not gravity condition. It was also discovered that, unlike in starch storage amyloplasts, all of the starch granules of statolith amyloplasts were encompassed by a fine filamentous, ribosome-excluding matrix. From light micrographic 3-D cell reconstructions, the absolute volume, number, and positional relationships between amyloplasts showed (i) that individual amyloplast volume increased in microgravity but remained constant in seedlings grown for up to three days on the clinostat, (ii) the number of amyloplasts per cell remained unchanged in microgravity but decreased on the clinostat, and (iii) the three-dimensional positions of amyloplasts were not random. Instead amyloplasts in microgravity were grouped near the cell centers while those from the clinostat appeared more dispersed. Taken together, these observations suggest that changing gravity stimulation can elicit feedback control over statolith mass by changing the size, number, and grouping of amyloplasts. These results support the starch-statolith theory of graviperception in higher plants and add to current models with a new feedback control loop as a mechanism for modulation of statolith responsiveness to inertial acceleration.

The unseen iceberg: Plant roots in arctic tundra

USGS Publications Warehouse

Iverson, Colleen M.; Sloan, Victoria L.; Sullivan, Patrick F.; Euskirchen, E.S.; McGuire, A. David; Norby, Richard J.; Walker, Anthony P.; Warren, Jeffrey M.; Wullschleger, Stan D.

2015-01-01

Plant roots play a critical role in ecosystem function in arctic tundra, but root dynamics in these ecosystems are poorly understood. To address this knowledge gap, we synthesized available literature on tundra roots, including their distribution, dynamics and contribution to ecosystem carbon and nutrient fluxes, and highlighted key aspects of their representation in terrestrial biosphere models. Across all tundra ecosystems, belowground plant biomass exceeded aboveground biomass, with the exception of polar desert tundra. Roots were shallowly distributed in the thin layer of soil that thaws annually, and were often found in surface organic soil horizons. Root traits – including distribution, chemistry, anatomy and resource partitioning – play an important role in controlling plant species competition, and therefore ecosystem carbon and nutrient fluxes, under changing climatic conditions, but have only been quantified for a small fraction of tundra plants. Further, the annual production and mortality of fine roots are key components of ecosystem processes in tundra, but extant data are sparse. Tundra root traits and dynamics should be the focus of future research efforts. Better representation of the dynamics and characteristics of tundra roots will improve the utility of models for the evaluation of the responses of tundra ecosystems to changing environmental conditions.

Imaging the Root Hair Morphology of Arabidopsis Seedlings in a Two-layer Microfluidic Platform

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

Aufrecht, Jayde A.; Ryan, Jennifer M.; Hasim, Sahar

Root hairs increase root surface area for better water uptake and nutrient absorption by the plant. Because they are small in size and often obscured by their natural environment, root hair morphology and function are difficult to study and often excluded from plant research. In recent years, microfluidic platforms have offered a way to visualize root systems at high resolution without disturbing the roots during transfer to an imaging system. The microfluidic platform presented here builds on previous plant-on-a-chip research by incorporating a two-layer device to confine the Arabidopsis thaliana main root to the same optical plane as the rootmore » hairs. This design enables the quantification of root hairs on a cellular and organelle level and also prevents z-axis drifting during the addition of experimental treatments. We describe how to store the devices in a contained and hydrated environment, without the need for fluidic pumps, while maintaining a gnotobiotic environment for the seedling. After the optical imaging experiment, the device may be disassembled and used as a substrate for atomic force or scanning electron microscopy while keeping fine root structures intact.« less

GTL1 and DF1 regulate root hair growth through transcriptional repression of ROOT HAIR DEFECTIVE 6-LIKE 4 in Arabidopsis

PubMed Central

Breuer, Christian; Kawamura, Ayako; Clark, Natalie M.; Morohashi, Kengo; Busch, Wolfgang; Benfey, Philip N.; Sozzani, Rosangela

2018-01-01

ABSTRACT How plants determine the final size of growing cells is an important, yet unresolved, issue. Root hairs provide an excellent model system with which to study this as their final cell size is remarkably constant under constant environmental conditions. Previous studies have demonstrated that a basic helix-loop helix transcription factor ROOT HAIR DEFECTIVE 6-LIKE 4 (RSL4) promotes root hair growth, but how hair growth is terminated is not known. In this study, we demonstrate that a trihelix transcription factor GT-2-LIKE1 (GTL1) and its homolog DF1 repress root hair growth in Arabidopsis. Our transcriptional data, combined with genome-wide chromatin-binding data, show that GTL1 and DF1 directly bind the RSL4 promoter and regulate its expression to repress root hair growth. Our data further show that GTL1 and RSL4 regulate each other, as well as a set of common downstream genes, many of which have previously been implicated in root hair growth. This study therefore uncovers a core regulatory module that fine-tunes the extent of root hair growth by the orchestrated actions of opposing transcription factors. PMID:29439132

Imaging the Root Hair Morphology of Arabidopsis Seedlings in a Two-layer Microfluidic Platform

DOE PAGES

Aufrecht, Jayde A.; Ryan, Jennifer M.; Hasim, Sahar; ...

2017-08-01

Root hairs increase root surface area for better water uptake and nutrient absorption by the plant. Because they are small in size and often obscured by their natural environment, root hair morphology and function are difficult to study and often excluded from plant research. In recent years, microfluidic platforms have offered a way to visualize root systems at high resolution without disturbing the roots during transfer to an imaging system. The microfluidic platform presented here builds on previous plant-on-a-chip research by incorporating a two-layer device to confine the Arabidopsis thaliana main root to the same optical plane as the rootmore » hairs. This design enables the quantification of root hairs on a cellular and organelle level and also prevents z-axis drifting during the addition of experimental treatments. We describe how to store the devices in a contained and hydrated environment, without the need for fluidic pumps, while maintaining a gnotobiotic environment for the seedling. After the optical imaging experiment, the device may be disassembled and used as a substrate for atomic force or scanning electron microscopy while keeping fine root structures intact.« less

Root induced changes of effective 1D hydraulic properties in a soil column.

PubMed

Scholl, P; Leitner, D; Kammerer, G; Loiskandl, W; Kaul, H-P; Bodner, G

Roots are essential drivers of soil structure and pore formation. This study aimed at quantifying root induced changes of the pore size distribution (PSD). The focus was on the extent of clogging vs. formation of pores during active root growth. Parameters of Kosugi's lognormal PSD model were determined by inverse estimation in a column experiment with two cover crops (mustard, rye) and an unplanted control. Pore dynamics were described using a convection-dispersion like pore evolution model. Rooted treatments showed a wider range of pore radii with increasing volumes of large macropores >500 μm and micropores <2.5 μm, while fine macropores, mesopores and larger micropores decreased. The non-rooted control showed narrowing of the PSD and reduced porosity over all radius classes. The pore evolution model accurately described root induced changes, while structure degradation in the non-rooted control was not captured properly. Our study demonstrated significant short term root effects with heterogenization of the pore system as dominant process of root induced structure formation. Pore clogging is suggested as a partial cause for reduced pore volume. The important change in micro- and large macropores however indicates that multiple mechanic and biochemical processes are involved in root-pore interactions.

Biocompatibility of sweetpotato and peanut in a hydroponic system

NASA Technical Reports Server (NTRS)

Mortley, D. G.; Loretan, P. A.; Hill, W. A.; Bonsi, C. K.; Morris, C. E.; Hall, R.; Sullen, D.

1998-01-01

'Georgia Red' peanut (Arachis hypogaea L.) and TU-82-155 sweetpotato [Ipomoea batatas (L.) Lam] were grown in monocultured or intercropped recirculating hydroponic systems in a greenhouse using the nutrient film technique (NFT). The objective was to determine whether growth and subsequent yield would be affected by intercropping. Treatments were sweetpotato monoculture (SP), peanut monoculture (PN), and sweetpotato and peanut grown in separate NFT channels but sharing a common nutrient solution (SP-PN). Greenhouse conditions ranged from 24 to 33 degrees C, 60% to 90% relative humidity (RH), and photosynthetic photon flux (PPF) of 200 to 1700 micromoles m-2 s-1. Sweetpotato cuttings (15 cm long) and 14-day-old seedlings of peanuts were planted into growth channels (0.15 x 0.15 x 1.2 m). Plants were spaced 25 cm apart within and 25 cm apart between growing channels. A modified half-Hoagland solution with a 1 N: 2.4 K ratio was used. Solution pH was maintained between 5.5 and 6.0 for treatments involving SP and 6.4 and 6.7 for PN. Electrical conductivity (EC) ranged between 1100 and 1200 microS cm-1. The number of storage roots per sweetpotato plant was similar for both SP and SP-PN. Storage root fresh and dry mass were 29% and 36% greater, respectively, for plants in the SP-PN treatment than for plants in the SP treatment. The percent dry mass of the storage roots, dry mass of fibrous and pencil roots, and the length-to-diameter ratio of storage roots were similar for SP and SP-PN sweetpotato plants. Likewise, foliage fresh and dry mass and harvest index were not significantly influenced by treatment. Total dry mass was 37% greater for PN than for SP-PN peanut plants, and pod dry mass was 82% higher. Mature and total seed dry mass and fibrous root dry mass were significantly greater for PN than for SP-PN plants. Harvest index (HI) was similar for both treatments. Root length tended to be lower for seedlings grown in the nutrient solution from the SP-PN treatment.

Connecting traces of galaxy evolution: the missing core mass-morphological fine structure relation

NASA Astrophysics Data System (ADS)

Bonfini, P.; Bitsakis, T.; Zezas, A.; Duc, P.-A.; Iodice, E.; González-Martín, O.; Bruzual, G.; González Sanoja, A. J.

2018-01-01

Deep exposure imaging of early-type galaxies (ETGs) are revealing the second-order complexity of these objects, which have been long considered uniform, dispersion-supported spheroidals. `Fine structure' features (e.g. ripples, plumes, tidal tails, rings) as well as depleted stellar cores (i.e. central light deficits) characterize a number of massive ETG galaxies, and can be interpreted as the result of galaxy-galaxy interactions. We discuss how the time-scale for the evolution of cores and fine structures are comparable, and hence it is expected that they develop in parallel after the major interaction event which shaped the ETG. Using archival data, we compare the `depleted stellar mass' (i.e. the mass missing from the depleted stellar core) against the prominence of the fine structure features, and observe that they correlate inversely. This result confirms our expectation that, while the supermassive black hole (SMBH) binary (constituted by the SMBHs of the merger progenitors) excavates the core via three-body interactions, the gravitational potential of the newborn galaxy relaxes, and the fine structures fade below detection levels. We expect the inverse correlation to hold at least within the first Gyr from the merger which created the SMBH binary; after then, the fine structure evolves independently.

Decomposition and nutrient release from fresh and dried pine roots under two fertilizer regimes

Treesearch

Kim H. Ludovici; Lance W. Kress

2006-01-01

Root decomposition and nutrient release are typically estimated from dried root tissues; however, it is unlikely that roots dehydrate prior to decomposing. Soil fertility and root diameter may also affect the rate of decomposition. This study monitored mass loss and nutrient concentrations of dried and fresh roots of two size classes (

Experimental evaluation of several key factors affecting root biomass estimation by 1500 MHz ground penetrating radar

Treesearch

John Bain; Frank Day; John Butnor

2017-01-01

Accurate quantification of coarse roots without disturbance represents a gap in our understanding of belowground ecology. Ground penetrating radar (GPR) has shown significant promise for coarse root detection and measurement, however root orientation relative to scanning transect direction, the difficulty identifying dead root mass, and the effects of root shadowing...

Quantifying root water extraction after drought recovery using sub-mm in situ empirical data

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

Dhiman, Indu; Bilheux, Hassina Z.; DeCarlo, Keito F.

Root-specific responses to stress are not well-known, and have been largely based on indirect measurements of bulk soil water extraction, which limits mechanistic modeling of root function. Here, we used neutron radiography to examine in situ root-soil water dynamics of a previously droughted black cottonwood ( Populus trichocarpa) seedling, contrasting water uptake by younger, thinner or older, thicker parts of the fine root system. The smaller diameter roots had greater water uptake capacity per unit surface area than the larger diameter roots, but they had less total surface area leading to less total water extraction; rates ranged from 0.0027 –more » 0.0116 g cm -2 hr -1. The finest most-active roots were not visible in the radiographs, indicating the need to include destructive sampling. Analysis based on bulk soil hydraulic properties indicated substantial redistribution of water via saturated/unsaturated flow, capillary wicking, and root hydraulic redistribution across the layers - suggesting water uptake dynamics following an infiltration event may be more complex than approximated by common soil hydraulic or root surface area modeling approaches. Lastly, our results highlight the need for continued exploration of root-trait specific water uptake rates in situ, and impacts of roots on soil hydraulic properties – both critical components for mechanistic modeling of root function.« less

Quantifying root water extraction after drought recovery using sub-mm in situ empirical data

DOE PAGES

Dhiman, Indu; Bilheux, Hassina Z.; DeCarlo, Keito F.; ...

2017-09-09

Root-specific responses to stress are not well-known, and have been largely based on indirect measurements of bulk soil water extraction, which limits mechanistic modeling of root function. Here, we used neutron radiography to examine in situ root-soil water dynamics of a previously droughted black cottonwood ( Populus trichocarpa) seedling, contrasting water uptake by younger, thinner or older, thicker parts of the fine root system. The smaller diameter roots had greater water uptake capacity per unit surface area than the larger diameter roots, but they had less total surface area leading to less total water extraction; rates ranged from 0.0027 –more » 0.0116 g cm -2 hr -1. The finest most-active roots were not visible in the radiographs, indicating the need to include destructive sampling. Analysis based on bulk soil hydraulic properties indicated substantial redistribution of water via saturated/unsaturated flow, capillary wicking, and root hydraulic redistribution across the layers - suggesting water uptake dynamics following an infiltration event may be more complex than approximated by common soil hydraulic or root surface area modeling approaches. Lastly, our results highlight the need for continued exploration of root-trait specific water uptake rates in situ, and impacts of roots on soil hydraulic properties – both critical components for mechanistic modeling of root function.« less

Early root growth and architecture of fast- and slow-growing Norway spruce (Picea abies) families differ-potential for functional adaptation.

PubMed

Hamberg, Leena; Velmala, Sannakajsa M; Sievänen, Risto; Kalliokoski, Tuomo; Pennanen, Taina

2018-06-01

The relationship between the growth rate of aboveground parts of trees and fine root development is largely unknown. We investigated the early root development of fast- and slow-growing Norway spruce (Picea abies (L.) H. Karst.) families at a developmental stage when the difference in size is not yet observed. Seedling root architecture data, describing root branching, were collected with the WinRHIZO™ image analysis system, and mixed models were used to determine possible differences between the two growth phenotypes. A new approach was used to investigate the spatial extent of root properties along the whole sample root from the base of 1-year-old seedlings to the most distal part of a root. The root architecture of seedlings representing fast-growing phenotypes showed ~30% higher numbers of root branches and tips, which resulted in larger root extensions and potentially a better ability to acquire nutrients. Seedlings of fast-growing phenotypes oriented and allocated root tips and biomass further away from the base of the seedling than those growing slowly, a possible advantage in nutrient-limited and heterogeneous boreal forest soils. We conclude that a higher long-term growth rate of the aboveground parts in Norway spruce may relate to greater allocation of resources to explorative roots that confers a competitive edge during early growth phases in forest ecosystems.

Upper Limit for $$\

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

Abadias, Juan Bofill

1984-01-01

Limits on the mass squared difference of neutrino mass eigenstatesmore » $$\\delta2 = m^2_1 - m^2_2$$, have been determined in a fine grained calorimeter exposed to the dichromatic beam at Fermilab. The fine grained calorimeter is located at a distance of 1.3 Km from the neutrino source making it suitable for oscillations studies. The interaction of a $$\

Quark mass variations of nuclear forces, BBN, and all that

NASA Astrophysics Data System (ADS)

Meissner, Ulf-G.

2014-03-01

In this talk, I discuss the modifications of the nuclear forces due to variations of the light quark masses and of the fine structure constant. This is based on the chiral nuclear effective field theory, that successfully describes a large body of data. The generation of the light elements in the Big Bang Nucleosynthesis provides important constraints on these modifications. In addition, I discuss the role of the anthropic principle in the triple-alpha process that underlies carbon and oxygen generation in hot stars. It appears that a fine-tuning of the quark masses and the fine structure constant within 2 to 3 per cent is required to make life on Earth viable. Supported in part by DFG, HGF and the BMBF.

[Allelopathy of garlic root exudates on different receiver vegetables].

PubMed

Zhou, Yan-li; Cheng, Zhi-hui; Meng, Huan-wen

2007-01-01

By the method of tissue culture under sterilized condition, this paper studied the allelopathy of garlic root exudates on lettuce, hot pepper, radish, cucumber, Chinese cabbage, and tomato. The results showed that garlic root exudates had no evident effects on the germination rate, germination index, shoot height, and protective enzyme system of test crops, but significantly increased the root length, aboveground fresh mass, and root fresh mass of lettuce, with the RIs being +0.163, +0.106, +0.318, respectively. The exudates also increased the root length of Chinese cabbage, with a RI of +0.120. For other test crops, no significant difference was observed between the treatments and the control. Garlic root exudates significantly increased the chlorophyll content and root activity of the receiver vegetables. The strongest promotion effects were found on chlorophyll content in radish, with RI being +0.282, and on root activity of cucumber, with RI being +0.184. The exudates promoted the nutrient absorption of all the receiver vegetables.

Spectral Discrimination of Fine and Coarse Mode Aerosol Optical Depth from AERONET Direct Sun Data of Singapore and South-East Asia

NASA Astrophysics Data System (ADS)

Salinas Cortijo, S.; Chew, B.; Liew, S.

2009-12-01

Aerosol optical depth combined with the Angstrom exponent and its derivative, are often used as a qualitative indicator of aerosol particle size, with Angstrom exp. values greater than 2 indicating small (fine mode) particles associated with urban pollution and bio-mass burning. Around this region, forest fires are a regular occurrence during the dry season, specially near the large land masses of Sumatra and Borneo. The practice of clearing land by burning the primary and sometimes secondary forest, results in a smog-like haze covering large areas of regional cities such as cities Singapore, Kuala Lumpur and sometimes the south of Thailand, often reducing visibility and increasing health problems for the local population. In Singapore, the sources of aerosols are mostly from fossil fuel burning (energy stations, incinerators, urban transport etc.) and from the industrial and urban areas. The proximity to the sea adds a possible oceanic source. However, as stated above and depending on the time of the year, there can be a strong bio-mass component coming from forest fires from various regions of the neighboring countries. Bio-mass related aerosol particles are typically characterized by showing a large optical depth and small, sub-micron particle size distributions. In this work, we analyze three years of direct Sun measurements performed with a multi-channel Cimel Sun-Photometer (part of the AERONET network) located at our site. In order to identify bio-mass burning events in this region, we perform a spectral discrimination between coarse and fine mode optical depth; subsequently, the fine mode parameters such as optical depth, optical ratio and fine mode Angstrom exponents (and its derivative) are used to identify possible bio-mass related events within the data set.

Wood pulp characterization by a novel photoacoustic sensor

NASA Astrophysics Data System (ADS)

Niemi, Jan; Löfqvist, Torbjörn

2012-08-01

In this paper we introduce a novel photoacoustic sensing technique that captures a photoacoustic signal excited by a laser light pulse after the light has propagated through a turbid medium. Simultaneously, the ultrasonic sound wave is captured after it has propagated through the same turbid medium. By combining the two signals, more information on the investigated medium can be obtained. Applications can be found in the pulp and paper industry where monitoring wood pulp compositions is of interest. Depending on its origin, pulp suspension contains different compositions of fibres and fibre fragments (fines). Poor control of the pulp composition leads to an unstable process that compromises the production, quality and energy efficiency in the pulp mill. The result shows the feasibility of the photoacoustic sensor in monitoring the mass fractions of fibres and fines in a pulp suspension. The first received echo, corresponding to the light interaction with the sample, showed a stronger correlation to the fines mass fraction compared to fibre mass fraction. The second echo, corresponding to the sound wave interaction with the sample, showed a much stronger correlation to fibre mass fraction than to fines mass fraction. Hence, it is proposed that by combining these two echoes, more information about the pulp suspension could be extracted than from any other sensor built on a single sensing principle.

Lead distribution and possible sources along vertical zone spectrum of typical ecosystems in the Gongga Mountain, eastern Tibetan Plateau

NASA Astrophysics Data System (ADS)

Luo, Ji; Tang, Ronggui; Sun, Shouqin; Yang, Dandan; She, Jia; Yang, Peijun

2015-08-01

A total of 383 samples from soil, plant, litterfall and precipitation in four typical ecosystems of Gongga Mountain were collected. Pb concentrations of samples were measured and analyzed. The results showed mean Pb concentrations in different soil layers were in the order of O > A > C, and mean Pb concentrations of the aboveground parts of plant was 3.60 ± 2.54 mg kg-1, with the minimum value of 0.77 mg kg-1 and the maximum value of 10.90 mg kg-1. Pb concentrations in soil's O-horizon and A-horizon showed a downward trend with increasing elevation (the determination coefficient R2 was 0.9478, 0.7918 and 0.9759 respectively). In contrast to other soil layers, the level of Pb concentrations in O-horizon (incomplete decomposition) was significantly high. Litterfall decomposition, atmospheric deposition and the unique climate could be main factors leading high Pb accumulation in soil's O-horizon. What's more, significant correlation (R2 = 0.8126, P < 0.05) was found between Pb concentrations in fine roots and soil's A-horizon confirms that fine roots could adsorb and accumulate Pb materials in soil. In general, the fact that Pb inputted into the typical ecosystems in the Gongga Mountain via long-range transportation and deposition of the atmosphere from external Pb sources could be confirmed by the HYSPLIT model and the ratio of CPb/CAl in plants (leaves) and CPb/CAl in litterfall. The mining activities and increasing anthropogenic activities (tourism development) could be main sources of Pb in this area. In order to better understand Pb sources and eco-risks of these typical ecosystems, litterfall decomposition characteristics, biomass of productivity of forest ecosystem, Pb isotopic tracing among air mass, twigs, leaves, litterfall and O-horizon soil in this vertical belt should also be taken into consideration.

Dirac gauginos, R symmetry and the 125 GeV Higgs

DOE PAGES

Bertuzzo, Enrico; Frugiuele, Claudia; Gregoire, Thomas; ...

2015-04-20

We study a supersymmetric scenario with a quasi exact R-symmetry in light of the discovery of a Higgs resonance with a mass of 125 GeV. In such a framework, the additional adjoint superfields, needed to give Dirac masses to the gauginos, contribute both to the Higgs mass and to electroweak precision observables. We then analyze the interplay between the two aspects, finding regions in parameter space in which the contributions to the precision observables are under control and a 125 GeV Higgs boson can be accommodated. Furthermore, we estimate the fine-tuning of the model finding regions of the parameter spacemore » still unexplored by the LHC with a fine-tuning considerably improved with respect to the minimal supersymmetric scenario. In particular, sizable non-holomorphic (non-supersoft) adjoints masses are required to reduce the fine-tuning.« less

Blue wild-rye grass competition increases the effect of ozone on ponderosa pine seedlings.

PubMed

Andersen, C P; Hogsett, W E; Plocher, M; Rodecap, K; Lee, E H

2001-03-01

Individual ponderosa pine (Pinus ponderosa Dougl. ex Laws.) seedlings were grown in mesocosms with three densities of blue wild-rye grass (Elymus glaucus Buckl.) (equivalent to 0, 32 or 88 plants m-2) to determine if the presence of a natural competitor alters the response of ponderosa pine seedlings to ozone. After 3 years of ozone exposure, grass presence reduced total ponderosa pine dry mass by nearly 50%, whereas ozone alone had no significant effect on ponderosa pine growth. The combination of ozone and grass further reduced needle, stem and branch dry mass significantly below that induced by grass competition alone. Root:shoot ratios increased in response to the combined grass and ozone treatments. Grass competition significantly reduced soluble sugar concentrations in all ponderosa pine tissue components examined. Starch concentrations were highly variable but did not differ significantly between treatments. Ozone significantly reduced soluble sugar concentrations in fine roots and stems. In the absence of grass, ozone-treated seedlings tended to have higher tissue N concentrations than controls. In the presence of grass, ozone-treated seedlings had lower N concentrations than controls, resulting in a significant interaction between these two stresses in 1- and 2-year-old needles. Needle C:N ratios decreased in response to grass competition, as a result of increased N concentration and no change in C concentration. The opposite response was observed in ozone-treated seedlings as a result of decreased N concentrations, indicating that ozone-treated seedlings were unable to take up or retain as much nitrogen when grown in the presence of grass. We conclude that ponderosa pine seedlings are more susceptible to ozone when grown in competition with blue wild-rye grass.

Characterization and Cytotoxicity of PM<0.2, PM0.2–2.5 and PM2.5–10 around MSWI in Shanghai, China

PubMed Central

Cao, Lingling; Zeng, Jianrong; Liu, Ke; Bao, Liangman; Li, Yan

2015-01-01

Background: The potential impact of municipal solid waste incineration (MSWI), which is an anthropogenic source of aerosol emissions, is of great public health concern. This study investigated the characterization and cytotoxic effects of ambient ultrafine particles (PM<0.2), fine particles (PM0.2–2.5) and coarse particles (PM2.5–10) collected around a municipal solid waste incineration (MSWI) plant in the Pudong district of Shanghai. Methods: Mass concentrations of trace elements in particulate matter (PM) samples were determined using ICP-MS (Inductively Coupled Plasma Mass Spectrometry). The cytotoxicity of sampled atmospheric PM was evaluated by cell viability and reactive oxygen species (ROS) levels in A549 cells. Result: The mass percentage of PM0.2–2.5 accounted for 72.91% of the total mass of PM. Crustal metals (Mg, Al, and Ti) were abundant in the coarse particles, while the anthropogenic elements (V, Ni, Cu, Zn, Cd, and Pb) were dominant in the fine particles. The enrichment factors of Zn, Cd and Pb in the fine and ultrafine particles were extremely high (>100). The cytotoxicity of the size-resolved particles was in the order of coarse particles < fine particles < ultrafine particles. Conclusions: Fine particles dominated the MSWI ambient particles. Emissions from the MSWI could bring contamination of anthropogenic elements (Zn, Cd and Pb) into ambient environment. The PM around the MSWI plant displayed an additive toxic effect, and the ultrafine and fine particles possessed higher biological toxicity than the coarse particles. PMID:25985309

Identification of qSOR1, a major rice QTL involved in soil-surface rooting in paddy fields.

PubMed

Uga, Yusaku; Hanzawa, Eiko; Nagai, Shinsei; Sasaki, Kazuhiro; Yano, Masahiro; Sato, Tadashi

2012-01-01

Specific Indonesian lowland rice (Oryza sativa L.) cultivars elongate thick primary roots on the soil surface of paddy fields. To clarify the genetic factors controlling soil-surface rooting, we performed quantitative trait locus (QTL) analyses using 124 recombinant inbred lines (RILs) derived from a cross between Gemdjah Beton, an Indonesian lowland rice cultivar with soil-surface roots, and Sasanishiki, a Japanese lowland rice cultivar without soil-surface roots. These cultivars and the RILs were tested for soil-surface rooting in a paddy field. We identified four regions of chromosomes 3, 4, 6, and 7 that were associated with soil-surface rooting in the field. Among them, one major QTL was located on the long arm of chromosome 7. This QTL explained 32.5-53.6% of the total phenotypic variance across three field evaluations. To perform fine mapping of this QTL, we measured the basal root growth angle of crown roots at the seedling stage in seven BC(2)F(3) recombinant lines grown in small cups in a greenhouse. The QTL was mapped between markers RM21941 and RM21976, which delimit an 812-kb interval in the reference cultivar Nipponbare. We have designated this QTL qSOR1 (quantitative trait locus for SOIL SURFACE ROOTING 1).

Assessing the potential for rhizoremediation of PCB contaminated soils in northern regions using native tree species.

PubMed

Slater, Heather; Gouin, Todd; Leigh, Mary Beth

2011-06-01

Rhizosphere bioremediation of polychlorinated biphenyls (PCBs) offers a potentially inexpensive approach to remediating contaminated soils that is particularly attractive in remote regions including the Arctic. We assessed the abilities of two tree species native to Alaska, Salix alaxensis (felt-leaf willow) and Picea glauca (white spruce), to promote microbial biodegradation of PCBs via the release of phytochemicals upon fine root death. Crushed fine roots, biphenyl (PCB analogue) or salicylate (willow secondary compound) were added to microcosms containing soil spiked with PCBs and resultant PCB disappearance, soil toxicity and microbial community changes were examined. After 180d, soil treated with willow root crushates showed a significantly greater PCB loss than untreated soils for some PCB congeners, including the toxic congeners, PCB 77, 105 and 169, and showed a similar PCB loss pattern (in both extent of degradation and congeners degraded) to biphenyl-treated microcosms. Neither P. glauca (white spruce) roots nor salicylate enhanced PCB loss, indicating that biostimulation is plant species specific and was not mediated by salicylate. Soil toxicity assessed using the Microtox bioassay indicated that the willow treatment resulted in a less toxic soil environment. Molecular microbial community analyses indicated that biphenyl and salicylate promoted shifts in microbial community structure and composition that differed distinctly from each other and from the crushed root treatments. The biphenyl utilizing bacterium, Cupriavidus spp. was isolated from the soil. The findings suggest that S. alaxensis may be an effective plant for rhizoremediation by altering microbial community structure, enhancing the loss of some PCB congeners and reducing the toxicity of the soil environment. Copyright © 2011 Elsevier Ltd. All rights reserved.

The structure of some cytoplasmic components of plant cells in relation to the biochemical properties of isolated particles.

PubMed

HODGE, A J; MARTIN, E M; MORTON, R K

1957-01-25

1. Electron micrographs of thin sections of material fixed with buffered osmium tetroxide have been used for comparison of the fine structure of isolated cytoplasmic particles from silver beet petioles and roots of germinating wheat with that of the cytoplasm of the intact cells. 2. Mitochondria of wheat roots have an external double membrane and poorly oriented internal double membranes. As compared with the structures seen in situ, the isolated mitochondria showed evidence of some disorganisation of the fine internal structure, probably due to osmotic effects. The possible influence of such changes on the enzymic properties of the isolated mitochondria is discussed. 3. The isolated plant microsomes are mainly spherical vesicular structures consisting of (a) an outer membrane enclosing (b) either an homogeneous slightly dense material (wheat root microsomes) or some granular dense material (silver beet microsomes) and (c) small dense particles, mostly associated with the vesicle membranes. 4. The cytoplasm of the wheat root cells does not contain any structures similar to the isolated microsomes but has a very dense reticular network, consisting of membranes with associated small dense particles, here called the endoplasmic reticulum. The observations indicate that the isolated microsomes arise mainly by rupture and transformation of the membranes of this structure. The effects of such extensive changes in the lipoprotein membranes on the enzymic activities of the endoplasmic reticulum, as studied in isolated microsomes, is discussed. 5. Meristematic wheat root cells contain structures which consist of smooth membranes with associated vacuoles and are similar to the Golgi zones of animal cells. The membranes of these zones probably contribute to the microsomal fraction under the conditions of preparation used for the enzymic and chemical studies previously reported.

THE STRUCTURE OF SOME CYTOPLASMIC COMPONENTS OF PLANT CELLS IN RELATION TO THE BIOCHEMICAL PROPERTIES OF ISOLATED PARTICLES

PubMed Central

Hodge, A. J.; Martin, E. M.; Morton, R. K.

1957-01-01

1. Electron micrographs of thin sections of material fixed with buffered osmium tetroxide have been used for comparison of the fine structure of isolated cytoplasmic particles from silver beet petioles and roots of germinating wheat with that of the cytoplasm of the intact cells. 2. Mitochondria of wheat roots have an external double membrane and poorly oriented internal double membranes. As compared with the structures seen in situ, the isolated mitochondria showed evidence of some disorganisation of the fine internal structure, probably due to osmotic effects. The possible influence of such changes on the enzymic properties of the isolated mitochondria is discussed. 3. The isolated plant microsomes are mainly spherical vesicular structures consisting of (a) an outer membrane enclosing (b) either an homogeneous slightly dense material (wheat root microsomes) or some granular dense material (silver beet microsomes) and (c) small dense particles, mostly associated with the vesicle membranes. 4. The cytoplasm of the wheat root cells does not contain any structures similar to the isolated microsomes but has a very dense reticular network, consisting of membranes with associated small dense particles, here called the endoplasmic reticulum. The observations indicate that the isolated microsomes arise mainly by rupture and transformation of the membranes of this structure. The effects of such extensive changes in the lipoprotein membranes on the enzymic activities of the endoplasmic reticulum, as studied in isolated microsomes, is discussed. 5. Meristematic wheat root cells contain structures which consist of smooth membranes with associated vacuoles and are similar to the Golgi zones of animal cells. The membranes of these zones probably contribute to the microsomal fraction under the conditions of preparation used for the enzymic and chemical studies previously reported. PMID:13416311

Mass Spectrometry Based Profiling and Imaging of Various Ginsenosides from Panax ginseng Roots at Different Ages

PubMed Central

Lee, Jae Won; Ji, Seung-Heon; Lee, Young-Seob; Choi, Doo Jin; Choi, Bo-Ram; Kim, Geum-Soog; Baek, Nam-In; Lee, Dae Young

2017-01-01

(1) Background: Panax ginseng root is one of the most important herbal products, and the profiling of ginsenosides is critical for the quality control of ginseng roots at different ages in the herbal markets. Furthermore, interest in assessing the contents as well as the localization of biological compounds has been growing. The objective of this study is to carry out the mass spectrometry (MS)-based profiling and imaging of ginsenosides to assess ginseng roots at different ages; (2) Methods: Optimal ultra performance liquid chromatography coupled to quadrupole time of flight/MS (UPLC-QTOF/MS) was used to profile various ginsenosides from P. ginseng roots. Matrix-assisted laser desorption ionization (MALDI)-time of flight (TOF)/MS-based imaging was also optimized to visualize ginsenosides in ginseng roots; (3) Results: UPLC-QTOF/MS was used to profile 30 ginsenosides with high mass accuracy, with an in-house library constructed for the fast and exact identification of ginsenosides. Using this method, the levels of 14 ginsenosides were assessed in P. ginseng roots cultivated for 4, 5, and 6 years. The optimal MALDI-imaging MS (IMS) was also applied to visualize the 14 ginsenosides in ginseng roots. As a result, the MSI cross sections showed the localization of 4 ginsenoside ions ([M + K]+) in P. ginseng roots at different ages; (4) Conclusions: The contents and localization of various ginsenosides differ depending on the cultivation years of P. ginseng roots. Furthermore, this study demonstrated the utility of MS-based profiling and imaging of ginsenosides for the quality control of ginseng roots. PMID:28538661

Mass Spectrometry Based Profiling and Imaging of Various Ginsenosides from Panax ginseng Roots at Different Ages.

PubMed

Lee, Jae Won; Ji, Seung-Heon; Lee, Young-Seob; Choi, Doo Jin; Choi, Bo-Ram; Kim, Geum-Soog; Baek, Nam-In; Lee, Dae Young

2017-05-24

(1) Background: Panax ginseng root is one of the most important herbal products, and the profiling of ginsenosides is critical for the quality control of ginseng roots at different ages in the herbal markets. Furthermore, interest in assessing the contents as well as the localization of biological compounds has been growing. The objective of this study is to carry out the mass spectrometry (MS)-based profiling and imaging of ginsenosides to assess ginseng roots at different ages; (2) Methods: Optimal ultra performance liquid chromatography coupled to quadrupole time of flight/MS (UPLC-QTOF/MS) was used to profile various ginsenosides from P. ginseng roots. Matrix-assisted laser desorption ionization (MALDI)-time of flight (TOF)/MS-based imaging was also optimized to visualize ginsenosides in ginseng roots; (3) Results: UPLC-QTOF/MS was used to profile 30 ginsenosides with high mass accuracy, with an in-house library constructed for the fast and exact identification of ginsenosides. Using this method, the levels of 14 ginsenosides were assessed in P. ginseng roots cultivated for 4, 5, and 6 years. The optimal MALDI-imaging MS (IMS) was also applied to visualize the 14 ginsenosides in ginseng roots. As a result, the MSI cross sections showed the localization of 4 ginsenoside ions ([M + K]⁺) in P. ginseng roots at different ages; (4) Conclusions: The contents and localization of various ginsenosides differ depending on the cultivation years of P. ginseng roots. Furthermore, this study demonstrated the utility of MS-based profiling and imaging of ginsenosides for the quality control of ginseng roots.

A comparison of three approaches for simulating fine-scale surface winds in support of wildland fire management. Part II. An exploratory study of the effect of simulated winds on fire growth simulations

Treesearch

Jason M. Forthofer; Bret W. Butler; Charles W. McHugh; Mark A. Finney; Larry S. Bradshaw; Richard D. Stratton; Kyle S. Shannon; Natalie S. Wagenbrenner

2014-01-01

The effect of fine-resolution wind simulations on fire growth simulations is explored. The wind models are (1) a wind field consisting of constant speed and direction applied everywhere over the area of interest; (2) a tool based on the solution of the conservation of mass only (termed mass-conserving model) and (3) a tool based on a solution of conservation of mass...

Long-Term Simulated Atmospheric Nitrogen Deposition Alters Leaf and Fine Root Decomposition

EPA Science Inventory

Atmospheric nitrogen deposition has been suggested to increase forest carbon sequestration across much of the Northern Hemisphere; slower organic matter decomposition could contribute to this increase. At four sugar maple (Acer saccharum)-dominated northern hardwood forests, we p...

Technical note: Application of geophysical tools for tree root studies in forest ecosystems in complex soils

NASA Astrophysics Data System (ADS)

Rodríguez-Robles, Ulises; Arredondo, Tulio; Huber-Sannwald, Elisabeth; Alfredo Ramos-Leal, José; Yépez, Enrico A.

2017-11-01

While semiarid forests frequently colonize rocky substrates, knowledge is scarce on how roots garner resources in these extreme habitats. The Sierra San Miguelito Volcanic Complex in central Mexico exhibits shallow soils and impermeable rhyolitic-rock outcrops, which impede water movement and root placement beyond the soil matrix. However, rock fractures, exfoliated rocks and soil pockets potentially permit downward water percolation and root growth. With ground-penetrating radar (GPR) and electrical resistivity tomography (ERT), two geophysical methods advocated by Jayawickreme et al. (2014) to advance root ecology, we advanced in the method development studying root and water distribution in shallow rocky soils and rock fractures in a semiarid forest. We calibrated geophysical images with in situ root measurements, and then extrapolated root distribution over larger areas. Using GPR shielded antennas, we identified both fine and coarse pine and oak roots from 0.6 to 7.5 cm diameter at different depths into either soil or rock fractures. We also detected, trees anchoring their trunks using coarse roots underneath rock outcroppings. With ERT, we tracked monthly changes in humidity at the soil-bedrock interface, which clearly explained spatial root distribution of both tree species. Geophysical methods have enormous potential in elucidating root ecology. More interdisciplinary research could advance our understanding in belowground ecological niche functions and their role in forest ecohydrology and productivity.

Imaging tree roots with borehole radar

Treesearch

John R. Butnor; Kurt H. Johnsen; Per Wikstrom; Tomas Lundmark; Sune Linder

2006-01-01

Ground-penetrating radar has been used to de-tect and map tree roots using surface-based antennas in reflection mode. On amenable soils these methods can accurately detect lateral tree roots. In some tree species (e.g. Pinus taeda, Pinus palustris), vertically orientated tap roots directly beneath the tree, comprise most of the root mass. It is...

Background aerosol over the Himalayas and Tibetan Plateau: observed characteristics of aerosol mass loading

NASA Astrophysics Data System (ADS)

Liu, B.; Cong, Z.; Wang, Y.; Xin, J.; Wan, X.; Pan, Y.; Liu, Z.; Wang, Y.; Zhang, G.; Kang, S.

2016-12-01

To investigate the atmospheric aerosols of the Himalayas and Tibetan Plateau (HTP), an observation network was established within the region's various ecosystems, including at Ngari, Qomolangma (QOMS), Nam Co, and SouthEastern Tibetan (SET) stations. In this paper we illustrate aerosol mass loadings by integrating in situ measurements with satellite and ground-based remote sensing datasets for the 2011-2013 period, on both local and large scales. Mass concentrations of these surface atmospheric aerosols were relatively low and varied with land cover, showing a general tendency of Ngari and QOMS (barren sites) > Nam Co (grassland site) > SET (forest site). Bimodal mass distributions of size-segregated particles were found at all sites, with a relatively small peak in accumulation mode and a more notable peak in coarse mode. Diurnal variations in fine aerosol masses generally displayed a bi-peak pattern at the QOMS, Nam Co and SET stations and a single-peak pattern at the Ngari station, controlled by the effects of local geomorphology, mountain-valley breeze circulation and aerosol emissions. Combining surface aerosols data and atmospheric-column aerosol optical properties, the TSP mass and aerosol optical depth (AOD) of the Multi-angle Imaging Spectroradiometer (MISR) generally decreased as land cover changed from barren to forest, in inverse relation to the PM2.5 ratios. The seasonality of aerosol mass parameters was land-cover dependent. Over forest and grassland areas, TSP mass, PM2.5 mass, MISR-AOD and fine-mode AOD were higher in spring and summer, followed by relatively lower values in autumn and winter. At the barren site (the QOMS station), there were inconsistent seasonal variations between surface TSP mass (PM2.5 mass) and atmospheric column AOD (fine-mode AOD). Our findings implicate that, HTP aerosol masses (especially their reginal characteristics and fine particle emissions) need to be treated sensitively in relation to assessments of their climatic effect

Effects of temperature segregation on the volumetric and mechanistic properties of asphalt mixtures : research project capsule.

DOT National Transportation Integrated Search

2015-02-01

Material segregation in asphalt mixtures is a non-uniform distribution of coarse : and fine aggregates through its masses, i.e., concentration of coarse materials : in some area and fine materials in others. During construction, the coarse and : fine...

Balance of dark and luminous mass in rotating galaxies.

PubMed

McGaugh, Stacy S

2005-10-21

A fine balance between dark and baryonic mass is observed in spiral galaxies. As the contribution of the baryons to the total rotation velocity increases, the contribution of the dark matter decreases by a compensating amount. This poses a fine-tuning problem for galaxy formation models, and may point to new physics for dark matter particles or even a modification of gravity.

Stoichiometry in aboveground and fine roots of Seriphidium korovinii in desert grassland in response to artificial nitrogen addition.

PubMed

Li, Lei; Gao, Xiaopeng; Gui, Dongwei; Liu, Bo; Zhang, Bo; Li, Xiangyi

2017-07-01

Nitrogen (N) input by atmospheric deposition and human activity enhances the availability of N in various ecosystems, which may further affect N and phosphorus (P) cycling and use by plants. However, the internal use of N, P, and N:P stoichiometry by plants in response to N supply, particularly for grass species in a desert steppe ecosystem, remains unclear. In this work, a field experiment was conducted at an infertile area in a desert steppe to investigate the effects of N fertilizer addition rates on the stoichiometry of N and P in a dominant grass species, Seriphidium korovinii. Results showed that for both aboveground and fine roots of S. korovinii, N inputs exponentially increased the N concentration and N:P ratios while P concentrations decreased. Meanwhile, the relationships between N and P concentrations for both aboveground and fine roots were significantly negative. Furthermore, while the N concentrations in the plants were relatively low, P concentrations were higher than the global means, resulting in a relatively low N:P ratio. These results suggest that the stoichiometric characteristics of N were different from that of P for this desert plant species. Results also show that the intraspecific variations in the main element traits (N, P, and N:P ratios) were consistent at the whole-plant level. Our results also suggest that N should be part of any short-term fertilization plan that is part of a management strategy designed to restore degraded desert grassland. These findings highlight that nutrient addition by atmospheric N deposition and human activity can have significant effects on the internal use of N and P by plants. Therefore, establishing a nutrient-conservation strategy for desert grasslands is important.

Elucidating rhizosphere processes by mass spectrometry - A review.

PubMed

Rugova, Ariana; Puschenreiter, Markus; Koellensperger, Gunda; Hann, Stephan

2017-03-01

The presented review discusses state-of-the-art mass spectrometric methods, which have been developed and applied for investigation of chemical processes in the soil-root interface, the so-called rhizosphere. Rhizosphere soil's physical and chemical characteristics are to a great extent influenced by a complex mixture of compounds released from plant roots, i.e. root exudates, which have a high impact on nutrient and trace element dynamics in the soil-root interface as well as on microbial activities or soil physico-chemical characteristics. Chemical characterization as well as accurate quantification of the compounds present in the rhizosphere is a major prerequisite for a better understanding of rhizosphere processes and requires the development and application of advanced sampling procedures in combination with highly selective and sensitive analytical techniques. During the last years, targeted and non-targeted mass spectrometry-based methods have emerged and their combination with specific separation methods for various elements and compounds of a wide polarity range have been successfully applied in several studies. With this review we critically discuss the work that has been conducted within the last decade in the context of rhizosphere research and elemental or molecular mass spectrometry emphasizing different separation techniques as GC, LC and CE. Moreover, selected applications such as metal detoxification or nutrient acquisition will be discussed regarding the mass spectrometric techniques applied in studies of root exudates in plant-bacteria interactions. Additionally, a more recent isotope probing technique as novel mass spectrometry based application is highlighted. Copyright © 2017 Elsevier B.V. All rights reserved.

Selection of microsites by grizzly bears to excavate biscuitroots (Lomatium cous)

USGS Publications Warehouse

Mattson, D.J.

1997-01-01

Roots of the biscuitroot (Lomatium cous) are a common food of grizzly bears (Ursus arctos horribilis) in drier parts of their southern range. I used random sampling and locations of radiomarked bears in the Yellowstone ecosystem to investigate the importance of mass and starch content of roots, digability of the site, and density of plants relative to selection of sites by grizzly bears to dig biscuitroots. Where biscuitroots were present, most differences between dug and undug sites were related to digability of the site and mass and starch content of roots. Grizzly bears more often dug in sites where average milligrams of starch per kilogram of pull per root (a??energy gain) was high. Density of biscuitroots was not related to selection of sites by grizzly bears. Mass of biscuitroot stems also provided relatively little information about mass of roots. Distribution of biscuitroots was associated with increased cover of rocks and exposure to wind, and with decreased slopes and cover of forbs. Digs by grizzly bears were associated with the presence of biscuitroots, proximity to edge of forest, and increased cover of rocks. Results were consistent with previously observed tendencies of grizzly bears to concentrate their feeding within 50-100 m of cover.

Diesel emissions significantly influence composition and mutagenicity of ambient particles: a case study in São Paulo, Brazil.

PubMed

Carvalho-Oliveira, R; Pozo, R M K; Lobo, D J A; Lichtenfels, A J F C; Martins-Junior, H A; Bustilho, J O W V; Saiki, M; Sato, I M; Saldiva, P H N

2005-05-01

In 2003, a bus strike paralyzed the fleet of buses in Sao Paulo, Brazil during 3 days, from 6 to 8 of April, the complete interruption of services being achieved on the 7th. We evaluated the effect of the absence of this source of pollution on the composition, mutagenicity, and toxicity of the fine particulate material collected during this period. Particles were sampled in glass fiber filters on days 7 and 15 of April of 2003 (strike and nonstrike days, respectively), using a high-volume sampler. Trace element determinations (As, Br, Co, Cl, Fe, La, Mn, Sb, Sc, and Th) of particulate material samples were carried out by neutron activation analysis. Sulfur determination was done by X-ray fluorescence analysis. The ratio between nonstrike/strike concentrations of hydrocarbons associated with automotive emissions (benzene, toluene, ethyl-benzene, and xylenes; BTEX) was determined by gas chromatography/mass spectrometry. Mutagenesis of testing solutions was determined by means of the Tradescantia micronucleus assay in early tetrads of Tradescantia pallida. The inhibition of mitosis of the cells of the primary meristema of the root tips of Allium cepa was used as an index of the toxicity. Fine particle trace element contents were lower during the strike. The concentrations of sulfur and BTEX were 50% and 39.3% lower, respectively, on the strike day. A significant (P=0.038) reduction of micronuclei induced by fine particles sampled during the strike was observed. No effect of the strike on toxicity was detected. These results indicate that a program aiming to reduce emissions of the bus fleet in our town may impact positively the air quality by reducing the mutagenic potential of ambient particles.

Quantifying root-reinforcement of river bank soils by four Australian tree species

NASA Astrophysics Data System (ADS)

Docker, B. B.; Hubble, T. C. T.

2008-08-01

The increased shear resistance of soil due to root-reinforcement by four common Australian riparian trees, Casuarina glauca, Eucalyptus amplifolia, Eucalyptus elata and Acacia floribunda, was determined in-situ with a field shear-box. Root pull-out strengths and root tensile-strengths were also measured and used to evaluate the utility of the root-reinforcement estimation models that assume simultaneous failure of all roots at the shear plane. Field shear-box results indicate that tree roots fail progressively rather than simultaneously. Shear-strengths calculated for root-reinforced soil assuming simultaneous root failure, yielded values between 50% and 215% higher than directly measured shear-strengths. The magnitude of the overestimate varies among species and probably results from differences in both the geometry of the root-system and tensile strengths of the root material. Soil blocks under A. floribunda which presents many, well-spread, highly-branched fine roots with relatively higher tensile strength, conformed most closely with root model estimates; whereas E. amplifolia, which presents a few, large, unbranched vertical roots, concentrated directly beneath the tree stem and of relatively low tensile strength, deviated furthest from model-estimated shear-strengths. These results suggest that considerable caution be exercised when applying estimates of increased shear-strength due to root-reinforcement in riverbank stability modelling. Nevertheless, increased soil shear strength provided by tree roots can be calculated by knowledge of the Root Area Ratio ( RAR) at the shear plane. At equivalent RAR values, A. floribunda demonstrated the greatest earth reinforcement potential of the four species studied.

[Effects of water storage in deeper soil layers on the root growth, root distribution and economic yield of cotton in arid area with drip irrigation under mulch].

PubMed

Luo, Hong-Hai; Zhang, Hong-Zhi; Zhang, Ya-Li; Zhang, Wang-Feng

2012-02-01

Taking cotton cultivar Xinluzao 13 as test material, a soil column culture expenment was conducted to study the effects of water storage in deeper (> 60 cm) soil layer on the root growth and its relations with the aboveground growth of the cultivar in arid area with drip irrigation under mulch. Two levels of water storage in 60-120 cm soil layer were installed, i. e., well-watered and no watering, and for each, the moisture content in 0-40 cm soil layer during growth period was controlled at two levels, i.e., 70% and 55% of field capacity. It was observed that the total root mass density of the cultivar and its root length density and root activity in 40-120 cm soil layer had significant positive correlations with the aboveground dry mass. When the moisture content in 0-40 cm soil layer during growth season was controlled at 70% of field capacity, the total root mass density under well-watered and no watering had less difference, but the root length density and root activity in 40-120 cm soil layer under well-watered condition increased, which enhanced the water consumption in deeper soil layer, increased the aboveground dry mass, and finally, led to an increased economic yield and higher water use efficiency. When the moisture content in 0-40 cm soil layer during growth season was controlled at 55% of field capacity and the deeper soil layer was well-watered, the root/shoot ratio and root length density in 40-120 cm soil layer and the root activity in 80-120 cm soil layer were higher, the water consumption in deeper soil layer increased, but it was still failed to adequately compensate for the negative effects of water deficit during growth season on the impaired growth of roots and aboveground parts, leading to a significant decrease in the economic yield, as compared with that at 70% of field capacity. Overall, sufficient water storage in deeper soil layer and a sustained soil moisture level of 65% -75% of field capacity during growth period could promote the downward growth of cotton roots, which was essential for achieving water-saving and high-yielding cultivation of cotton with drip irrigation under mulch.

Leaf δ15N as an indicator of arbuscular mycorrhizal nitrogen uptake in a coastal-plain forest (restinga forest) at Southeastern Brazil

NASA Astrophysics Data System (ADS)

Mardegan, S. F.; Valadares, R.; Martinelli, L.

2013-12-01

Restinga diversity contrasts with a series of adverse environmental conditions that constrain their development, including nutrient limitation. In this sense, the mutualistic symbiosis between plants and arbuscular mycorrhizal fungi (AMF) may contribute in nutrient acquisition, including nitrogen. However, this association deeply affects plant nitrogen isotopic composition (δ15N), since assimilation processes and biochemical reactions within the fungi may reflect in a delivered product with an isotopic composition about 8 to 10 ‰ lower than that observed at the fungal symbiont per se. Here we assessed if the association with AMF affects δ15N values of plant species from a coastal-plain forest (restinga forest) at Southeastern Brazil. Accordingly, we analyzed the nutritional and isotopic compositions from ecosystem key-compartments (soil, litter and leaves), relating plant δ15N with the colonization rates. The study was carried out in a permanent plot (1 ha) at a coastal-plain forest (restinga forest) at the Serra do Mar State Park, SP, Brazil. Sampled vegetation is characterized by the lack of a well-defined stratification and a rather open canopy. It also comprises trees ranging from 10 to 15-m high. Soils are deep and sandy, being characterized by high acidity, nutrient deficiency and a dense litter cover. We randomly collected five samples (250 mg) from topsoil (0-10 cm) and five to ten leaves from individuals belonging to 16 plant species of high relevance within the site (IVI index). We also collected superficial (0-10 cm depth) fine roots (5 g) and 13 samples (100 g) of fine litter next to the individuals sampled. Soil samples were air-dried, sieved, homogenized and used in the physical-chemical characterization. The remainder was ground to a fine powder to determine nitrogen concentrations and δ15N values. Leaves were dried at 50 °C, finely milled and used for the determination of nitrogen concentrations, C/N ratios and δ15N values. Root samples were cleared and stained according to Phillips and Hayman (1970), being scored for mycorrhizal colonization using the grid-line intersection method. We used analysis of variance (ANOVA) followed by a post hoc Tukey HSD test to determine differences amongst compartments. Spearman correlation coefficient was calculated to quantify the relationship between leaf δ15N and root colonization rates. Vegetation nitrogen concentration was around 22.5 g kg-1, being higher than those from litter and soil. Vegetation δ15N mean values were around -0.2 ‰, ranging from -1.6 to 2.0 ‰, being lower than those from the soils where they grow (mean values close to 3.0 ‰). Roots from all species were colonized, with the presence of typical AMF structures (hyphae, vesicles and arbuscules within root cortex). Root colonization rates ranged from less than 1 to about 55 %. In most cases, species with δ15N values had colonization rates exceeding 20 %. We observed an inverse relationship between the rate of root colonization and leaf δ15N of the species analyzed. These results suggest the importance of AMF symbiosis for nitrogen supply at such nutrient-limited coastal environments.

Impacts of mangrove density on surface sediment accretion, belowground biomass and biogeochemistry in Puttalam Lagoon, Sri Lanka

USGS Publications Warehouse

Phillips, D.H.; Kumara, M.P.; Jayatissa, L.P.; Krauss, Ken W.; Huxham, M.

2017-01-01

Understanding the effects of seedling density on sediment accretion, biogeochemistry and belowground biomass in mangrove systems can help explain ecological functioning and inform appropriate planting densities during restoration or climate change mitigation programs. The objectives of this study were to examine: 1) impacts of mangrove seedling density on surface sediment accretion, texture, belowground biomass and biogeochemistry, and 2) origins of the carbon (C) supplied to the mangroves in Palakuda, Puttalam Lagoon, Sri Lanka. Rhizophora mucronata propagules were planted at densities of 6.96, 3.26, 1.93 and 0.95 seedlings m−2along with an unplanted control (0 seedlings m−2). The highest seedling density generally had higher sediment accretion rates, finer sediments, higher belowground biomass, greatest number of fine roots and highest concentrations of C and nitrogen (N) (and the lowest C/N ratio). Sediment accretion rates, belowground biomass (over 1370 days), and C and N concentrations differed significantly between seedling densities. Fine roots were significantly greater compared to medium and coarse roots across all plantation densities. Sulphur and carbon stable isotopes did not vary significantly between different density treatments. Isotope signatures suggest surface sediment C (to a depth of 1 cm) is not derived predominantly from the trees, but from seagrass adjacent to the site.

A study on the relationship between mass concentrations, chemistry and number size distribution of urban fine aerosols in Milan, Barcelona and London

NASA Astrophysics Data System (ADS)

Rodríguez, S.; van Dingenen, R.; Putaud, J.-P.; Dell'Acqua, A.; Pey, J.; Querol, X.; Alastuey, A.; Chenery, S.; Ho, K.-F.; Harrison, R. M.; Tardivo, R.; Scarnato, B.; Gianelle, V.

2007-01-01

A physicochemical characterization of the urban fine aerosol (aerosol number size distribution, chemical composition and mass concentrations) in Milan, Barcelona and London is presented in this article. The objective is to obtain a comprehensive picture on the involvement of the microphysical processes of the aerosol dynamic in the: 1) regular evolution of the urban aerosol (daily, weekly and seasonal basis) and in the day-to-day variations (from clean-air to pollution-events), and 2) link between "aerosol chemistry and mass concentrations" with the "number size distribution". The mass concentrations of the fine PM2.5 aerosol exhibit a high correlation with the number concentration of particles >100 nm (which only accounts for <20% of the total number concentration N of fine aerosols) and do not correlate with the number of particles <100 nm ("ultrafine particles", which accounts for >80% of fine particles). Organic matter (OM) and black-carbon (BC) are the only aerosol components showing a significant correlation with ultrafine particles (attributed to vehicles emissions), whereas ammonium-nitrate, ammonium-sulphate and also OM and BC correlate with N>100(nm) (attributed to gas-to-particle transformation mechanisms and some primary emissions). Time series of the aerosol DpN diameter (dN/dlogD mode), mass PM2.5 concentrations and number N>100(nm) concentrations, exhibit correlated day-to-day variations which point to a significant involvement of condensation of semi-volatile compounds during urban pollution events. This agrees with the fact that ammonium-nitrate is the component exhibiting the highest increases from mid-to-high pollution episodes, when the highest DpN increases are observed. The results indicates that "fine PM2.5 particles urban pollution events" tend to occur when condensation processes have made particles grow enough to produce significant concentrations of N>100(nm). In contrast, because the low contribution of ultrafine particles to the fine aerosol mass concentrations, high "ultrafine particles N<100(nm) events" frequently occurs under low PM2.5 conditions. The data of this study point that vehicles emissions are strongly involved in this ultrafine particles aerosol pollution (for example, the "morning-rush-hours to nocturnal-background" concentrations ratio is 1.5-2.5 for "particles 10-100 nm" and <1.5 for both "particle >100 nm and PM2.5").

A study on the relationship between mass concentrations, chemistry and number size distribution of urban fine aerosols in Milan, Barcelona and London

NASA Astrophysics Data System (ADS)

Rodríguez, S.; van Dingenen, R.; Putaud, J.-P.; Dell'Acqua, A.; Pey, J.; Querol, X.; Alastuey, A.; Chenery, S.; Ho, K.-F.; Harrison, R.; Tardivo, R.; Scarnato, B.; Gemelli, V.

2007-05-01

A physicochemical characterization, including aerosol number size distribution, chemical composition and mass concentrations, of the urban fine aerosol captured in MILAN, BARCELONA and LONDON is presented in this article. The objective is to obtain a comprehensive picture of the microphysical processes involved in aerosol dynamics during the: 1) regular evolution of the urban aerosol (daily, weekly and seasonal basis) and in the day-to-day variations (from clean-air to pollution-events), and 2) the link between "aerosol chemistry and mass concentrations" with the "number size distribution". The mass concentrations of the fine PM2.5 aerosol exhibit a high correlation with the number concentration of >100 nm particles N>100 (nm) ("accumulation mode particles") which only account for <20% of the total number concentration N of fine aerosols; but do not correlate with the number of <100 nm particles ("ultrafine particles"), which accounts for >80% of fine particles number concentration. Organic matter and black-carbon are the only aerosol components showing a significant correlation with the ultrafine particles, attributed to vehicles exhausts emissions; whereas ammonium-nitrate, ammonium-sulphate and also organic matter and black-carbon correlate with N>100 (nm) and attributed to condensation mechanisms, other particle growth processes and some primary emissions. Time series of the aerosol DpN diameter (dN/dlogD mode), mass PM2.5 concentrations and number N>100 (nm) concentrations exhibit correlated day-to-day variations, which point to a significant involvement of condensation of semi-volatile compounds during urban pollution events. This agrees with the observation that ammonium-nitrate is the component exhibiting the highest increases from mid-to-high pollution episodes, when the highest DpN increases are observed. The results indicates that "fine PM2.5 particles urban pollution events" tend to occur when condensation processes have made particles grow large enough to produce significant number concentrations of N>100 (nm) ("accumulation mode particles"). In contrast, because the low contribution of ultrafine particles to the fine aerosol mass concentrations, high "ultrafine particles N<100(nm) events" frequently occurs under low PM2.5 conditions. The results of this study demonstrate that vehicles exhausts emissions are strongly involved in this ultrafine particles aerosol pollution.

Fine Aerosol Associated Non-Polar Organics in Jammu, AN Urban Location in the Foothill Region of North Western Himalayas

NASA Astrophysics Data System (ADS)

Yadav, S.; Bamotra, S.

2017-12-01

A comprehensive study was done on the mass, composition and sources of fine aerosol associated non-polar organics in Jammu, an urban location in the foothill region of North - Western Himalayas. Systematic multi-scale sampling was done from October, 2015 to February, 2017 to collect fine aerosol (PM2.5) samples every week using a Fine Particulate Sampler (Envirotech, APM 550 MFC) which operates at a constant flow rate of 16.7 L/minute. The Non- polar organic compounds comprising of n-alkanes, PAHs, isoprenoid hydrocarbons and nicotine were analyzed using Thermal desorption Gas Chromatography Mass Spectrometry (TD-GC-MS) method. The n-alkane associated diagnostic parameters include—mass weighted Averaged Chain Length (ACL); Carbon number with maximum concentration (Cmax); Petroleum derived n-alkanes (PNA%), Carbon Preference Index (CPI) and the percentage contribution of Wax n-alkanes from plants (WNA%). These diagnostic parameters along with PAH based molecular ratios were used to understand the diurnal and seasonal variations in different biogenic and petrogenic source contributions in this part of Himalayas. The presence of source specific tracers like Levoglucosan, Retene, Isoquinoline and nicotine also corroborated our findings. Further Fine aerosols associated Black Carbon, an important marker for burning was determined using Optical Transmissometer. Significant multiscale variations were found in the Fine aerosol load, associated Non-polar organics, source tracers/contributions and Black Carbon.

Relation between aerosol sources and meteorological parameters for inhalable atmospheric particles in Sao Paulo City, Brazil

NASA Astrophysics Data System (ADS)

Andrade, Fatima; Orsini, Celso; Maenhaut, Willy

Stacked filter units were used to collect atmospheric particles in separate coarse and fine fractions at the Sao Paulo University Campus during the winter of 1989. The samples were analysed by particle-induced X-ray emission (PIXE) and the data were subjected to an absolute principal component analysis (APCA). Five sources were identified for the fine particles: industrial emissions, which accounted for 13% of the fine mass; emissions from residual oil and diesel, explaining 41%; resuspended soil dust, with 28%; and emissions of Cu and of Mg, together with 18%. For the coarse particles, four sources were identified: soil dust, accounting for 59% of the coarse mass; industrial emissions, with 19%; oil burning, with 8%; and sea salt aerosol, with 14% of the coarse mass. A data set with various meteorological parameters was also subjected to APCA, and a correlation analysis was performed between the meteorological "absolute principal component scores" (APCS) and the APCS from the fine and coarse particle data sets. The soil dust sources for the fine and coarse aerosol were highly correlated with each other and were anticorrelated with the sea breeze component. The industrial components in the fine and coarse size fractions were also highly positively correlated. Furthermore, the industrial component was related with the northeasterly wind direction and, to a lesser extent, with the sea breeze component.

Physiological and growth responses of Centaurea maculosa (Asteraceae) to root herbivory under varying levels of interspecific plant competition and soil nitrogen availability.

PubMed

Steinger, Thomas; Müller-Schärer, Heinz

1992-08-01

Centaurea maculosa seedlings were grown in pots to study the effects of root herbivory by Agapeta zoegana L. (Lep.: Cochylidae) and Cyphocleonus achates Fahr. (Col.: Curculionidae), grass competition and nitrogen shortage (each present or absent), using a full factorial design. The aims of the study were to analyse the impact of root herbivory on plant growth, resource allocation and physiological processes, and to test if these plant responses to herbivory were influenced by plant competition and nitrogen availability. The two root herbivores differed markedly in their impact on plant growth. While feeding by the moth A. zoegana in the root cortex had no effect on shoot and root mass, feeding by the weevil C. achates in the central vascular tissue greatly reduced shoot mass, but not root mass, leading to a reduced shoot/root ratio. The absence of significant effects of the two herbivores on root biomass, despite considerable consumption, indicates that compensatory root growth occurred. Competition with grass affected plant growth more than herbivory and nutrient status, resulting in reduced shoot and root growth, and number of leaves. Nitrogen shortage did not affect plant growth directly but greatly influenced the compensatory capacity of Centaurea maculosa to root herbivory. Under high nitrogen conditions, shoot biomass of plants infested by the weevil was reduced by 30% compared with uninfested plants. However, under poor nitrogen conditions a 63% reduction was observed compared with corresponding controls. Root herbivory was the most important stress factor affecting plant physiology. Besides a relative increase in biomass allocation to the roots, infested plants also showed a significant increase in nitrogen concentration in the roots and a concomitant reduction in leaf nitrogen concentration, reflecting a redirection of the nitrogen to the stronger sink. The level of fructans was greatly reduced in the roots after herbivore feeding. This is thought to be a consequence of their mobilisation to support compensatory root growth. A preliminary model linking the effects of these root herbivores to the physiological processes of C. maculosa is presented.

A mass-conservative adaptive FAS multigrid solver for cell-centered finite difference methods on block-structured, locally-cartesian grids

NASA Astrophysics Data System (ADS)

Feng, Wenqiang; Guo, Zhenlin; Lowengrub, John S.; Wise, Steven M.

2018-01-01

We present a mass-conservative full approximation storage (FAS) multigrid solver for cell-centered finite difference methods on block-structured, locally cartesian grids. The algorithm is essentially a standard adaptive FAS (AFAS) scheme, but with a simple modification that comes in the form of a mass-conservative correction to the coarse-level force. This correction is facilitated by the creation of a zombie variable, analogous to a ghost variable, but defined on the coarse grid and lying under the fine grid refinement patch. We show that a number of different types of fine-level ghost cell interpolation strategies could be used in our framework, including low-order linear interpolation. In our approach, the smoother, prolongation, and restriction operations need never be aware of the mass conservation conditions at the coarse-fine interface. To maintain global mass conservation, we need only modify the usual FAS algorithm by correcting the coarse-level force function at points adjacent to the coarse-fine interface. We demonstrate through simulations that the solver converges geometrically, at a rate that is h-independent, and we show the generality of the solver, applying it to several nonlinear, time-dependent, and multi-dimensional problems. In several tests, we show that second-order asymptotic (h → 0) convergence is observed for the discretizations, provided that (1) at least linear interpolation of the ghost variables is employed, and (2) the mass conservation corrections are applied to the coarse-level force term.

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

EPA Science Inventory

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

Desirable plant root traits for protecting unstable slopes against landslides

NASA Astrophysics Data System (ADS)

Stokes, A.; Atger, C.; Bengough, G.; Fourcaud, T.; Sidle, R. C.

2009-04-01

A trait is defined as a distinct, quantitative property of organisms, usually measured at the individual level and used comparatively across species. Plant quantitative traits are extremely important for understanding the local ecology of any site. Plant height, architecture, root depth, wood density, leaf size and leaf nitrogen concentration control ecosystem processes and define habitat for other taxa. An engineer conjecturing as to how plant traits may directly influence physical processes occurring on sloping land just needs to consider how e.g. canopy architecture and litter properties influence the partitioning of rainfall among interception loss, infiltration and runoff. Plant traits not only influence abiotic processes occurring at a site, but also the habitat for animals and invertebrates. Depending on the goal of the landslide engineer, the immediate and long-term effects of plant traits in an environment must be considered if a site is to remain viable and ecologically successful. When vegetation is considered in models of slope stability, usually the only root parameters taken into consideration are tensile strength and root area ratio. Root system spatial structure is not considered, although the length, orientation and diameter of roots are recognized as being of importance. Thick roots act like soil nails on slopes, reinforcing soil in the same way that concrete is reinforced with steel rods. The spatial position of these thick roots also has an indirect effect on soil fixation in that the location of thin and fine roots will depend on the arrangement of thick roots. Thin and fine roots act in tension during failure on slopes and if they cross the slip surface, are largely responsible for reinforcing soil on slopes. Therefore, the most important trait to consider initially is rooting depth. To stabilize a slope against a shallow landslide, roots must cross the shear surface. The number and thickness of roots in this zone will therefore largely determine slope stability. Rooting depth is species dependent when soil conditions are not limiting and the number of horizontal lateral roots borne on the vertical roots usually changes with depth. Therefore, the number and orientation of roots that the shear surface intersects will change significantly with rooting depth for the same plant, even for magnitudes of only several cm. Similarly, depending on the geometry of the root system, the angle at which a root crosses the shear surface can also have an influence on its resistance to pullout and breakage. The angle at which a root emerges from the parent root is dependent on root type, depth and species (when soil conditions are not limiting). Due to the physiology of roots, a root branch can be initiated at any point along a parent root, but not necessarily emerge fully from the parent root. These traits, along with others including size, relative growth rate, regeneration strategies, wood structure and strength will be discussed with regard to their influence on slope stability. How each of these traits is influenced by soil conditions and plantation techniques is also of extreme importance to the landslide engineer. The presence of obstacles in the soil, as well as compaction, affects root length and branching pattern. Roots of many species of woody plants on shallow soils also tend to grow along fractures deep into the underlying bedrock which allows roots to locate supplies of nutrient and water rich pockets. Rooting depths of herbaceous species in water-limited environments are highly correlated with infiltration depth, but waterlogged soils can asphyxiate tree roots, resulting in shallow root systems. The need to understand and integrate each of these traits for a species is not easy. Therefore, we suggest a hierarchy whereby traits are considered in order of importance, along with how external factors influence their expression over time.

Life span and structure of ephemeral root modules of different functional groups from a desert system.

PubMed

Liu, Bo; He, Junxia; Zeng, Fanjiang; Lei, Jiaqiang; Arndt, Stefan K

2016-07-01

The terminal branch orders of plant root systems have been proposed as short-lived 'ephemeral' modules specialized for resource absorption. The occurrence of ephemeral root modules has so far only been reported for a temperate tree species and it is unclear if the concept also applies to other woody (shrub, tree) and herb species. Fine roots of 12 perennial dicotyledonous herb, shrub and tree species were monitored for two growing seasons using a branch-order classification, sequential sampling and rhizotrons in the Taklamakan desert. Two root modules existed in all three plant functional groups. Among the first five branch orders, the first two (perennial herbs, shrubs) or three (trees) root orders were ephemeral and had a primary anatomical structure, high nitrogen (N) concentrations, high respiration rates and very short life spans of 1-4 months, whereas the last two branch orders in all functional groups were perennial, with thicker diameters, no or collapsed cortex, distinct secondary growth, low N concentrations, low respiration rates, but much longer life spans. Ephemeral, short-lived root modules and long-lived, persistent root modules seem to be a general feature across many plant functional groups and could represent a basic root system design. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

GTL1 and DF1 regulate root hair growth through transcriptional repression of ROOT HAIR DEFECTIVE 6-LIKE 4 in Arabidopsis.

PubMed

Shibata, Michitaro; Breuer, Christian; Kawamura, Ayako; Clark, Natalie M; Rymen, Bart; Braidwood, Luke; Morohashi, Kengo; Busch, Wolfgang; Benfey, Philip N; Sozzani, Rosangela; Sugimoto, Keiko

2018-02-08

How plants determine the final size of growing cells is an important, yet unresolved, issue. Root hairs provide an excellent model system with which to study this as their final cell size is remarkably constant under constant environmental conditions. Previous studies have demonstrated that a basic helix-loop helix transcription factor ROOT HAIR DEFECTIVE 6-LIKE 4 (RSL4) promotes root hair growth, but how hair growth is terminated is not known. In this study, we demonstrate that a trihelix transcription factor GT-2-LIKE1 (GTL1) and its homolog DF1 repress root hair growth in Arabidopsis Our transcriptional data, combined with genome-wide chromatin-binding data, show that GTL1 and DF1 directly bind the RSL4 promoter and regulate its expression to repress root hair growth. Our data further show that GTL1 and RSL4 regulate each other, as well as a set of common downstream genes, many of which have previously been implicated in root hair growth. This study therefore uncovers a core regulatory module that fine-tunes the extent of root hair growth by the orchestrated actions of opposing transcription factors. © 2018. Published by The Company of Biologists Ltd.

The unseen iceberg: plant roots in arctic tundra.

PubMed

Iversen, Colleen M; Sloan, Victoria L; Sullivan, Patrick F; Euskirchen, Eugenie S; McGuire, A David; Norby, Richard J; Walker, Anthony P; Warren, Jeffrey M; Wullschleger, Stan D

2015-01-01

Plant roots play a critical role in ecosystem function in arctic tundra, but root dynamics in these ecosystems are poorly understood. To address this knowledge gap, we synthesized available literature on tundra roots, including their distribution, dynamics and contribution to ecosystem carbon and nutrient fluxes, and highlighted key aspects of their representation in terrestrial biosphere models. Across all tundra ecosystems, belowground plant biomass exceeded aboveground biomass, with the exception of polar desert tundra. Roots were shallowly distributed in the thin layer of soil that thaws annually, and were often found in surface organic soil horizons. Root traits - including distribution, chemistry, anatomy and resource partitioning - play an important role in controlling plant species competition, and therefore ecosystem carbon and nutrient fluxes, under changing climatic conditions, but have only been quantified for a small fraction of tundra plants. Further, the annual production and mortality of fine roots are key components of ecosystem processes in tundra, but extant data are sparse. Tundra root traits and dynamics should be the focus of future research efforts. Better representation of the dynamics and characteristics of tundra roots will improve the utility of models for the evaluation of the responses of tundra ecosystems to changing environmental conditions. No claim to original US Government works New Phytologist © 2014 New Phytologist Trust.

Water-soluble organic nitrogen in atmospheric fine particles (PM2.5) from northern California

NASA Astrophysics Data System (ADS)

Zhang, Qi; Anastasio, Cort; Jimenez-Cruz, Mike

2002-06-01

Recent studies have suggested that organic nitrogen (ON) is a ubiquitous and significant component of atmospheric dry and wet deposition, but very little is known about the concentrations and speciation of organic nitrogen in aerosol particles. In addition, while amino compounds also appear to be ubiquitous in atmospheric condensed phases, their contribution to organic nitrogen has not been previously quantified. To address these issues, we have characterized the water-soluble organic nitrogen and amino compounds in fine particles (PM2.5) collected in Davis, California, over a period of 1 year. Concentrations of water-soluble organic nitrogen (WSON) ranged from 3.1-57.8 nmol N m-3 air, peaking during winter and early spring, and typically accounted for ~20% of total nitrogen in Davis PM2.5. Assuming an average N-normalized molecular weight of 100 Da per N atom for WSON, particulate organic nitrogen had a median mass concentration of 1.6 μg m-3 air, and typically represented 18% of the total fine particle mass. The average mass of water-soluble ON in Davis PM2.5 was comparable to that of sulfate during the summer, but was significantly higher in winter. Total amino compounds (free plus combined forms) made up a significant portion of particulate organic nitrogen (median value equal to 23%), primarily due to the presence of combined amino compounds such as proteins and peptides. Total amino compounds had a median mass concentration of 290 ng m-3 air, and typically accounted for 3.3% of the total fine particle mass. These results indicate that organic nitrogen is a significant component of fine particles in northern California, and suggest that this group of compounds might play an important role in the ecological, radiative, and potential health effects of atmospheric fine particles in this region.

Slow decomposition of lower order roots: a key mechanism of root carbon and nutrient retention in the soil.

PubMed

Fan, Pingping; Guo, Dali

2010-06-01

Among tree fine roots, the distal small-diameter lateral branches comprising first- and second-order roots lack secondary (wood) development. Therefore, these roots are expected to decompose more rapidly than higher order woody roots. But this prediction has not been tested and may not be correct. Current evidence suggests that lower order roots may decompose more slowly than higher order roots in tree species associated with ectomycorrhizal (EM) fungi because they are preferentially colonized by fungi and encased by a fungal sheath rich in chitin (a recalcitrant compound). In trees associated with arbuscular mycorrhizal (AM) fungi, lower order roots do not form fungal sheaths, but they may have poorer C quality, e.g. lower concentrations of soluble carbohydrates and higher concentrations of acid-insolubles than higher order roots, thus may decompose more slowly. In addition, litter with high concentrations of acid insolubles decomposes more slowly under higher N concentrations (such as lower order roots). Therefore, we propose that in both AM and EM trees, lower order roots decompose more slowly than higher order roots due to the combination of poor C quality and high N concentrations. To test this hypothesis, we examined decomposition of the first six root orders in Fraxinus mandshurica (an AM species) and Larix gmelinii (an EM species) using litterbag method in northeastern China. We found that lower order roots of both species decomposed more slowly than higher order roots, and this pattern appears to be associated mainly with initial C quality and N concentrations. Because these lower order roots have short life spans and thus dominate root mortality, their slow decomposition implies that a substantial fraction of the stable soil organic matter pool is derived from these lower order roots, at least in the two species we studied.

Root (Botany)

Treesearch

Robert R. Ziemer

1981-01-01

Plant roots can contribute significantly to the stability of steep slopes. They can anchor through the soil mass into fractures in bedrock, can cross zones of weakness to more stable soil, and can provide interlocking long fibrous binders within a weak soil mass. In deep soil, anchoring to bedrock becomes negligible, and lateral reinforcement predominates

Assessment of bioavailability of heavy metal pollutants using soil isolates of Chlorella sp.

PubMed

Krishnamurti, Gummuluru S R; Subashchandrabose, Suresh R; Megharaj, Mallavarapu; Naidu, Ravi

2015-06-01

Biotests conducted with plants are presently used to estimate metal bioavailability in contaminated soils. But when plants are grown in soils, especially the plants with fine roots, root collection is easily biased and tedious. Indeed, at harvest, small amounts of soil can adhere to roots, resulting in overestimation of root metal content, and the finest roots are often discarded from the analysis because of their difficult and almost impossible recovery. This report presents a novel method for assessing the bioavailability of heavy metals in soils using microalgae. Two species of green unicellular microalgae were isolated from two highly contaminated soils and identified by phylogenetic and molecular evolutionary analyses as Chlorella sp. RBM and Chlorella sp. RHM. These two cultures were used to determine the metal uptake from metal-contaminated soils of South Australia as a novel, cost-effective, simple and rapid method for assessing the bioavailability of heavy metals in soils. The suggested method is an attempt to achieve a realistic estimate of bioavailability which overcomes the inherent drawback of root metal contamination in the bioavailability indices so far reported.

Assessment of cadmium accumulation, toxicity, and tolerance in Brassicaceae and Fabaceae plants--implications for phytoremediation.

PubMed

Anjum, Naser A; Umar, Shahid; Iqbal, Muhammad

2014-09-01

This study, based on a greenhouse pot culture experiment conducted with 15-day-old rapeseed (Brassica campestris L. cv. Pusa Gold; family Brassicaceae) and moong bean (Vigna radiata L. Wilczek cv. Pusa Ratna; family Fabaceae) plants treated with cadmium (Cd) concentrations (0, 50, and 100 mg kg(-1) soil), investigates their potential for Cd accumulation and tolerance, and dissects the underlying basic physiological/biochemical mechanisms. In both species, plant dry mass decreased, while Cd concentration of both root and shoot increased with increase in soil Cd. Roots harbored a higher amount of Cd (vs. shoot) in B. campestris, while the reverse applied to V. radiata. By comparison, root Cd concentration was higher in B. campestris than in V. radiata. The high Cd concentrations in B. campestris roots and V. radiata shoots led to significant elevation in oxidative indices, as measured in terms of electrolyte leakage, H2O2 content, and lipid peroxidation. Both plants displayed differential adaptation strategies to counteract the Cd burden-caused anomalies in their roots and shoots. In B. campestris, increasing Cd burden led to a significantly decreased reduced glutathione (GSH) content but a significant increase in activities of GSH reductase (GR), GSH peroxidase (GPX), and GSH sulfotransferase (GST). However, in V. radiata, increasing Cd burden caused significant increase in GSH content and GR activity, but a significant decline in activities of GPX and GST. Cross talks on Cd burden of tissues and the adapted Cd tolerance strategies against Cd burden-accrued toxicity indicated that B. campestris and V. radiata are good Cd stabilizer and Cd extractor, respectively, wherein a fine tuning among the major components (GR, GPX, GST, GSH) of the GSH redox system helped the plants to counteract differentially the Cd load-induced anomalies in tissues. On the whole, the physiological/biochemical characterization of the B. campestris and V. radiata responses to varying Cd concentrations can be of great help in elaborating the innovative plant-based remediation technologies for metal/metalloid-contaminated sites.

Higuchi equation: derivation, applications, use and misuse.

PubMed

Siepmann, Juergen; Peppas, Nicholas A

2011-10-10

Fifty years ago, the legendary Professor Takeru Higuchi published the derivation of an equation that allowed for the quantification of drug release from thin ointment films, containing finely dispersed drug into a perfect sink. This became the famous Higuchi equation whose fiftieth anniversary we celebrate this year. Despite the complexity of the involved mass transport processes, Higuchi derived a very simple equation, which is easy to use. Based on a pseudo-steady-state approach, a direct proportionality between the cumulative amount of drug released and the square root of time can be demonstrated. In contrast to various other "square root of time" release kinetics, the constant of proportionality in the classical Higuchi equation has a specific, physically realistic meaning. The major benefits of this equation include the possibility to: (i) facilitate device optimization, and (ii) to better understand the underlying drug release mechanisms. The equation can also be applied to other types of drug delivery systems than thin ointment films, e.g., controlled release transdermal patches or films for oral controlled drug delivery. Later, the equation was extended to other geometries and related theories have been proposed. The aim of this review is to highlight the assumptions the derivation of the classical Higuchi equation is based on and to give an overview on the use and potential misuse of this equation as well as of related theories. Copyright © 2011 Elsevier B.V. All rights reserved.

Nutrient Effects on Belowground Organic Matter in a ...

EPA Pesticide Factsheets

Belowground structure and carbon dioxide emission rates were examined in minerogenic marshes of the North Inlet estuary, a system dominated by depositional processes and typical of the southeastern USA. Three areas were sampled: a long-term nutrient enrichment experiment (Goat Island); a fringing marsh that only receives drainage from an entirely forested watershed (upper Crab Haul Creek); and three locations along a creek basin that receives drainage from a residential and golf course development situated at its headwaters (Debidue Creek). Responses to fertilization at Goat Island were an increase in soil organic matter, an increase in number of rhizomes, enlarged rhizome diameters, decreased fine root mass, and increased carbon dioxide emission rates. At the Crab Haul Creek, the greatest abundances of coarse roots and rhizomes were observed in the high marsh compared to the low marsh and creekbank. The upper and mid Debidue Creek, which may be influenced by nutrient inputs associated with land development, had significantly fewer rhizomes compared to the mouth, which was dominated by exchange with bay waters. Carbon dioxide emission rates at the fertilized Goat Island plots were similar in magnitude to the upper Debidue Creek and significantly greater than the Goat Island control plots and the Crab Haul Creek. Inputs of sediment and particulates in marshes dominated by depositional processes such as the North Inlet may buffer the system from adverse effects of

Can diversity in root architecture explain plant water use efficiency? A modeling study

PubMed Central

Tron, Stefania; Bodner, Gernot; Laio, Francesco; Ridolfi, Luca; Leitner, Daniel

2015-01-01

Drought stress is a dominant constraint to crop production. Breeding crops with adapted root systems for effective uptake of water represents a novel strategy to increase crop drought resistance. Due to complex interaction between root traits and high diversity of hydrological conditions, modeling provides important information for trait based selection. In this work we use a root architecture model combined with a soil-hydrological model to analyze whether there is a root system ideotype of general adaptation to drought or water uptake efficiency of root systems is a function of specific hydrological conditions. This was done by modeling transpiration of 48 root architectures in 16 drought scenarios with distinct soil textures, rainfall distributions, and initial soil moisture availability. We find that the efficiency in water uptake of root architecture is strictly dependent on the hydrological scenario. Even dense and deep root systems are not superior in water uptake under all hydrological scenarios. Our results demonstrate that mere architectural description is insufficient to find root systems of optimum functionality. We find that in environments with sufficient rainfall before the growing season, root depth represents the key trait for the exploration of stored water, especially in fine soils. Root density, instead, especially near the soil surface, becomes the most relevant trait for exploiting soil moisture when plant water supply is mainly provided by rainfall events during the root system development. We therefore concluded that trait based root breeding has to consider root systems with specific adaptation to the hydrology of the target environment. PMID:26412932

Can diversity in root architecture explain plant water use efficiency? A modeling study.

PubMed

Tron, Stefania; Bodner, Gernot; Laio, Francesco; Ridolfi, Luca; Leitner, Daniel

2015-09-24

Drought stress is a dominant constraint to crop production. Breeding crops with adapted root systems for effective uptake of water represents a novel strategy to increase crop drought resistance. Due to complex interaction between root traits and high diversity of hydrological conditions, modeling provides important information for trait based selection. In this work we use a root architecture model combined with a soil-hydrological model to analyze whether there is a root system ideotype of general adaptation to drought or water uptake efficiency of root systems is a function of specific hydrological conditions. This was done by modeling transpiration of 48 root architectures in 16 drought scenarios with distinct soil textures, rainfall distributions, and initial soil moisture availability. We find that the efficiency in water uptake of root architecture is strictly dependent on the hydrological scenario. Even dense and deep root systems are not superior in water uptake under all hydrological scenarios. Our results demonstrate that mere architectural description is insufficient to find root systems of optimum functionality. We find that in environments with sufficient rainfall before the growing season, root depth represents the key trait for the exploration of stored water, especially in fine soils. Root density, instead, especially near the soil surface, becomes the most relevant trait for exploiting soil moisture when plant water supply is mainly provided by rainfall events during the root system development. We therefore concluded that trait based root breeding has to consider root systems with specific adaptation to the hydrology of the target environment.

Root exudation and root development of lettuce (Lactuca sativa L. cv. Tizian) as affected by different soils

PubMed Central

Neumann, G.; Bott, S.; Ohler, M. A.; Mock, H.-P.; Lippmann, R.; Grosch, R.; Smalla, K.

2014-01-01

Development and activity of plant roots exhibit high adaptive variability. Although it is well-documented, that physicochemical soil properties can strongly influence root morphology and root exudation, particularly under field conditions, a comparative assessment is complicated by the impact of additional factors, such as climate and cropping history. To overcome these limitations, in this study, field soils originating from an unique experimental plot system with three different soil types, which were stored at the same field site for 10 years and exposed to the same agricultural management practice, were used for an investigation on effects of soil type on root development and root exudation. Lettuce (Lactuca sativa L. cv. Tizian) was grown as a model plant under controlled environmental conditions in a minirhizotrone system equipped with root observation windows (rhizoboxes). Root exudates were collected by placing sorption filters onto the root surface followed by subsequent extraction and GC-MS profiling of the trapped compounds. Surprisingly, even in absence of external stress factors with known impact on root exudation, such as pH extremes, water and nutrient limitations/toxicities or soil structure effects (use of sieved soils), root growth characteristics (root length, fine root development) as well as profiles of root exudates were strongly influenced by the soil type used for plant cultivation. The results coincided well with differences in rhizosphere bacterial communities, detected in field-grown lettuce plants cultivated on the same soils (Schreiter et al., this issue). The findings suggest that the observed differences may be the result of plant interactions with the soil-specific microbiomes. PMID:24478764

Root exudation and root development of lettuce (Lactuca sativa L. cv. Tizian) as affected by different soils.

PubMed

Neumann, G; Bott, S; Ohler, M A; Mock, H-P; Lippmann, R; Grosch, R; Smalla, K

2014-01-01

Development and activity of plant roots exhibit high adaptive variability. Although it is well-documented, that physicochemical soil properties can strongly influence root morphology and root exudation, particularly under field conditions, a comparative assessment is complicated by the impact of additional factors, such as climate and cropping history. To overcome these limitations, in this study, field soils originating from an unique experimental plot system with three different soil types, which were stored at the same field site for 10 years and exposed to the same agricultural management practice, were used for an investigation on effects of soil type on root development and root exudation. Lettuce (Lactuca sativa L. cv. Tizian) was grown as a model plant under controlled environmental conditions in a minirhizotrone system equipped with root observation windows (rhizoboxes). Root exudates were collected by placing sorption filters onto the root surface followed by subsequent extraction and GC-MS profiling of the trapped compounds. Surprisingly, even in absence of external stress factors with known impact on root exudation, such as pH extremes, water and nutrient limitations/toxicities or soil structure effects (use of sieved soils), root growth characteristics (root length, fine root development) as well as profiles of root exudates were strongly influenced by the soil type used for plant cultivation. The results coincided well with differences in rhizosphere bacterial communities, detected in field-grown lettuce plants cultivated on the same soils (Schreiter et al., this issue). The findings suggest that the observed differences may be the result of plant interactions with the soil-specific microbiomes.

Reassessment of Loblolly Pine Decline on the Oakmulgee Ranger District, Talladega National Forest, Alabama

Treesearch

Nolan J. Hess; William J. Otroana; John P. Jones; Arthur J. Goddard; Charles H. Walkinshaw

1999-01-01

Loblolly pine (Pinus taeda L.) decline has been a management concern on the Oakmulgee Ranger District since the 1960's. The symptoms include sparse crowns, reduced radial growth, deterioration of fine roots, decline, and mortality of loblolly pine by age 50.

Association of Pinus banksiana Lamb. and Populus tremuloides Michx. seedling fine roots with Sistotrema brinkmannii (Bres.) J. Erikss. (Basidiomycotina)

Treesearch

Lynette R. Potvin; Dana L. Richter; Martin F. Jurgensen; R. Kasten Dumroese

2012-01-01

Sistotrema brinkmannii (Bres.) J. Erikss. (Basidiomycotina, Hydanaceae), commonly regarded as a wood decay fungus, was consistently isolated from bareroot nursery Pinus banksiana Lamb. seedlings. S. brinkmannii was found in ectomycorrhizae formed by Thelephora terrestris Ehrh., ...

Anthropogenic fugitive, combustion and industrial dust is a significant, underrepresented fine particulate matter source in global atmospheric models

NASA Astrophysics Data System (ADS)

Philip, Sajeev; Martin, Randall V.; Snider, Graydon; Weagle, Crystal L.; van Donkelaar, Aaron; Brauer, Michael; Henze, Daven K.; Klimont, Zbigniew; Venkataraman, Chandra; Guttikunda, Sarath K.; Zhang, Qiang

2017-04-01

Global measurements of the elemental composition of fine particulate matter across several urban locations by the Surface Particulate Matter Network reveal an enhanced fraction of anthropogenic dust compared to natural dust sources, especially over Asia. We develop a global simulation of anthropogenic fugitive, combustion, and industrial dust which, to our knowledge, is partially missing or strongly underrepresented in global models. We estimate 2-16 μg m-3 increase in fine particulate mass concentration across East and South Asia by including anthropogenic fugitive, combustion, and industrial dust emissions. A simulation including anthropogenic fugitive, combustion, and industrial dust emissions increases the correlation from 0.06 to 0.66 of simulated fine dust in comparison with Surface Particulate Matter Network measurements at 13 globally dispersed locations, and reduces the low bias by 10% in total fine particulate mass in comparison with global in situ observations. Global population-weighted PM2.5 increases by 2.9 μg m-3 (10%). Our assessment ascertains the urgent need of including this underrepresented fine anthropogenic dust source into global bottom-up emission inventories and global models.

Impact of treated wastewater on growth, respiration and hydraulic conductivity of citrus root systems in light and heavy soils.

PubMed

Paudel, Indira; Cohen, Shabtai; Shaviv, Avi; Bar-Tal, Asher; Bernstein, Nirit; Heuer, Bruria; Ephrath, Jhonathan

2016-06-01

Roots interact with soil properties and irrigation water quality leading to changes in root growth, structure and function. We studied these interactions in an orchard and in lysimeters with clay and sandy loam soils. Minirhizotron imaging and manual sampling showed that root growth was three times lower in the clay relative to sandy loam soil. Treated wastewater (TWW) led to a large reduction in root growth with clay (45-55%) but not with sandy loam soil (<20%). Treated wastewater increased salt uptake, membrane leakage and proline content, and decreased root viability, carbohydrate content and osmotic potentials in the fine roots, especially in clay. These results provide evidence that TWW challenges and damages the root system. The phenology and physiology of root orders were studied in lysimeters. Soil type influenced diameter, specific root area, tissue density and cortex area similarly in all root orders, while TWW influenced these only in clay soil. Respiration rates were similar in both soils, and root hydraulic conductivity was severely reduced in clay soil. Treated wastewater increased respiration rate and reduced hydraulic conductivity of all root orders in clay but only of the lower root orders in sandy loam soil. Loss of hydraulic conductivity increased with root order in clay and clay irrigated with TWW. Respiration and hydraulic properties of all root orders were significantly affected by sodium-amended TWW in sandy loam soil. These changes in root order morphology, anatomy, physiology and hydraulic properties indicate rapid and major modifications of root systems in response to differences in soil type and water quality. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Phytoextraction of initial cutting of Salix matsudana for Cd and Cu.

PubMed

Wang, Wen-Wen; Cheng, Liu Ke; Hao, Jie Wei; Guan, Xin; Tian, Xing-Jun

2016-06-27

Salix species are widely used as vegetation filters because of their flourishing root system and fast growth rate. However, studies have yet to determine whether the root system functions in vegetable filters with mixed heavy metal (HM) pollution or whether initial cutting participates in the phytoextraction of HMs. This study aims to determine the function of the root system and initial cutting as vegetation filters in the absorption and accumulation of Cd and Cu. Thick (>1 cm in diameter) and fine (<1 cm in diameter) initial cuttings of Salix matsudana were planted in a nutrient solution with single and mixed (Cd + Cu) treatments. The roots of several initial cuttings were removed daily to eradicate rhizofiltration. Results revealed that the existence of the root system altered distribution and interaction of Cd and Cu in plant organs and enhanced tolerance and phytoextraction capacity of plants. The initial cuttings could also absorb and accumulate HMs in the early growth stages of willow without roots. Cu inhibited the plant absorption and accumulation of Cd and promoted Cd transport to shoots. Cd inhibited the Cu absorption of the root system. Our study provided essential data regarding woody species as vegetation filters of HM pollution.

Allometric growth and allocation in forests: a perspective from FLUXNET.

PubMed

Wolf, Adam; Field, Christopher B; Berry, Joseph A

2011-07-01

To develop a scheme for partitioning the products of photosynthesis toward different biomass components in land-surface models, a database on component mass and net primary productivity (NPP), collected from FLUXNET sites, was examined to determine allometric patterns of allocation. We found that NPP per individual of foliage (Gfol), stem and branches (Gstem), coarse roots (Gcroot) and fine roots (Gfroot) in individual trees is largely explained (r2 = 67-91%) by the magnitude of total NPP per individual (G). Gfol scales with G isometrically, meaning it is a fixed fraction of G ( 25%). Root-shoot trade-offs were manifest as a slow decline in Gfroot, as a fraction of G, from 50% to 25% as stands increased in biomass, with Gstem and Gcroot increasing as a consequence. These results indicate that a functional trade-off between aboveground and belowground allocation is essentially captured by variations in G, which itself is largely governed by stand biomass and only secondarily by site-specific resource availability. We argue that forests are characterized by strong competition for light, observed as a race for individual trees to ascend by increasing partitioning toward wood, rather than by growing more leaves, and that this competition stronglyconstrains the allocational plasticity that trees may be capable of. The residual variation in partitioning was not related to climatic or edaphic factors, nor did plots with nutrient or water additions show a pattern of partitioning distinct from that predicted by G alone. These findings leverage short-term process studies of the terrestrial carbon cycle to improve decade-scale predictions of biomass accumulation in forests. An algorithm for calculating partitioning in land-surface models is presented.

Branching patterns of root systems: quantitative analysis of the diversity among dicotyledonous species

PubMed Central

Pagès, Loïc

2014-01-01

Background and Aims Root branching, and in particular acropetal branching, is a common and important developmental process for increasing the number of growing tips and defining the distribution of their meristem size. This study presents a new method for characterizing the results of this process in natura from scanned images of young, branched parts of excavated roots. The method involves the direct measurement or calculation of seven different traits. Methods Young plants of 45 species of dicots were sampled from fields and gardens with uniform soils. Roots were separated, scanned and then measured using ImageJ software to determine seven traits related to root diameter and interbranch distance. Results The traits exhibited large interspecific variations, and covariations reflecting trade-offs. For example, at the interspecies level, the spacing of lateral roots (interbranch distance along the parent root) was strongly correlated to the diameter of the finest roots found in the species, and showed a continuum between two opposite strategies: making dense and fine lateral roots, or thick and well-spaced laterals. Conclusions A simple method is presented for classification of branching patterns in roots that allows relatively quick sampling and measurements to be undertaken. The feasibilty of the method is demonstrated for dicotyledonous species and it has the potential to be developed more broadly for other species and a wider range of enivironmental conditions. PMID:25062886

High-resolution synchrotron imaging shows that root hairs influence rhizosphere soil structure formation.

PubMed

Koebernick, Nicolai; Daly, Keith R; Keyes, Samuel D; George, Timothy S; Brown, Lawrie K; Raffan, Annette; Cooper, Laura J; Naveed, Muhammad; Bengough, Anthony G; Sinclair, Ian; Hallett, Paul D; Roose, Tiina

2017-10-01

In this paper, we provide direct evidence of the importance of root hairs on pore structure development at the root-soil interface during the early stage of crop establishment. This was achieved by use of high-resolution (c. 5 μm) synchrotron radiation computed tomography (SRCT) to visualise both the structure of root hairs and the soil pore structure in plant-soil microcosms. Two contrasting genotypes of barley (Hordeum vulgare), with and without root hairs, were grown for 8 d in microcosms packed with sandy loam soil at 1.2 g cm -3 dry bulk density. Root hairs were visualised within air-filled pore spaces, but not in the fine-textured soil regions. We found that the genotype with root hairs significantly altered the porosity and connectivity of the detectable pore space (> 5 μm) in the rhizosphere, as compared with the no-hair mutants. Both genotypes showed decreasing pore space between 0.8 and 0.1 mm from the root surface. Interestingly the root-hair-bearing genotype had a significantly greater soil pore volume-fraction at the root-soil interface. Effects of pore structure on diffusion and permeability were estimated to be functionally insignificant under saturated conditions when simulated using image-based modelling. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Vitality and chemistry of roots of red spruce in forest floors of stands with a gradient of soil Al/Ca ratios in the northeastern United States

USGS Publications Warehouse

Wargo, P.M.; Vogt, K.; Vogt, D.; Holifield, Q.; Tilley, J.; Lawrence, G.; David, M.

2003-01-01

Number of living root tips per branch, percent dead roots, percent mycorrhizae and mycorrhizal morphotype, response of woody roots to wounding and colonization by fungi, and concentrations of starch, soluble sugars, phenols, percent C and N and C/N ratio, and Al Ca, Fe, K, Mg, Mn, and P were measured for 2 consecutive years in roots of red spruce (Picea rubens Sarg.) in stands in the northeastern United States (nine in 1993 and two additional in 1994) dominated by red spruce and with a gradient of forest floor exchangeable Al/Ca ratios. Root vitality was measured for nonwoody and coarse woody roots; chemical variables were measured for nonwoody (<1 mm), fine woody (1 to <2 mm), and coarse woody (2 to <5 mm) roots. There were significant differences among sites for all variables, particularly in 1993, although few were related to the Al/Ca ratio gradient. Percent mycorrhizae decreased, while some morphotypes increased or decreased as the Al/Ca ratio increased. In nonwoody roots, N increased as the Al/Ca ratio increased. Most sampled trees appeared to be in good or fair health, suggesting that an adverse response of these root variables to high Al concentrations may be apparent only after a significant change in crown health.

Search for gluinos and scalar quarks in pp collisions at square root[s] = 1.8 TeV using the missing energy plus multijets signature.

PubMed

Affolder, T; Akimoto, H; Akopian, A; Albrow, M G; Amaral, P; Amidei, D; Anikeev, K; Antos, J; Apollinari, G; Arisawa, T; Artikov, A; Asakawa, T; Ashmanskas, W; Azfar, F; Azzi-Bacchetta, P; Bacchetta, N; Bachacou, H; Bailey, S; de Barbaro, P; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Baroiant, S; Barone, M; Bauer, G; Bedeschi, F; Belforte, S; Bell, W H; Bellettini, G; Bellinger, J; Benjamin, D; Bensinger, J; Beretvas, A; Berge, J P; Berryhill, J; Bhatti, A; Binkley, M; Bisello, D; Bishai, M; Blair, R E; Blocker, C; Bloom, K; Blumenfeld, B; Blusk, S R; Bocci, A; Bodek, A; Bokhari, W; Bolla, G; Bonushkin, Y; Bortoletto, D; Boudreau, J; Brandl, A; van den Brink, S; Bromberg, C; Brozovic, M; Brubaker, E; Bruner, N; Buckley-Geer, E; Budagov, J; Budd, H S; Burkett, K; Busetto, G; Byon-Wagner, A; Byrum, K L; Cabrera, S; Calafiura, P; Campbell, M; Carithers, W; Carlson, J; Carlsmith, D; Caskey, W; Castro, A; Cauz, D; Cerri, A; Chan, A W; Chang, P S; Chang, P T; Chapman, J; Chen, C; Chen, Y C; Cheng, M-T; Chertok, M; Chiarelli, G; Chirikov-Zorin, I; Chlachidze, G; Chlebana, F; Christofek, L; Chu, M L; Chung, Y S; Ciobanu, C I; Clark, A G; Connolly, A; Conway, J; Cordelli, M; Cranshaw, J; Cropp, R; Culbertson, R; Dagenhart, D; D'Auria, S; DeJongh, F; Dell'Agnello, S; Dell'Orso, M; Demortier, L; Deninno, M; Derwent, P F; Devlin, T; Dittmann, J R; Dominguez, A; Donati, S; Done, J; D'Onofrio, M; Dorigo, T; Eddy, N; Einsweiler, K; Elias, J E; Engels, E; Erbacher, R; Errede, D; Errede, S; Fan, Q; Feild, R G; Fernandez, J P; Ferretti, C; Field, R D; Fiori, I; Flaugher, B; Foster, G W; Franklin, M; Freeman, J; Friedman, J; Frisch, H J; Fukui, Y; Furic, I; Galeotti, S; Gallas, A; Gallinaro, M; Gao, T; Garcia-Sciveres, M; Garfinkel, A F; Gatti, P; Gay, C; Gerdes, D W; Giannetti, P; Giromini, P; Glagolev, V; Glenzinski, D; Gold, M; Goldstein, J; Gorelov, I; Goshaw, A T; Gotra, Y; Goulianos, K; Green, C; Grim, G; Gris, P; Groer, L; Grosso-Pilcher, C; Guenther, M; Guillian, G; Guimaraes da Costa, J; Haas, R M; Haber, C; Hahn, S R; Hall, C; Handa, T; Handler, R; Hao, W; Happacher, F; Hara, K; Hardman, A D; Harris, R M; Hartmann, F; Hatakeyama, K; Hauser, J; Heinrich, J; Heiss, A; Herndon, M; Hill, C; Hoffman, K D; Holck, C; Hollebeek, R; Holloway, L; Hughes, R; Huston, J; Huth, J; Ikeda, H; Incandela, J; Introzzi, G; Iwai, J; Iwata, Y; James, E; Jones, M; Joshi, U; Kambara, H; Kamon, T; Kaneko, T; Karr, K; Kasha, H; Kato, Y; Keaffaber, T A; Kelley, K; Kelly, M; Kennedy, R D; Kephart, R; Khazins, D; Kikuchi, T; Kilminster, B; Kim, B J; Kim, D H; Kim, H S; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kirby, M; Kirk, M; Kirsch, L; Klimenko, S; Koehn, P; Kondo, K; Konigsberg, J; Korn, A; Korytov, A; Kovacs, E; Kroll, J; Kruse, M; Kuhlmann, S E; Kurino, K; Kuwabara, T; Laasanen, A T; Lai, N; Lami, S; Lammel, S; Lancaster, J; Lancaster, M; Lander, R; Lath, A; Latino, G; LeCompte, T; Lee, A M; Lee, K; Leone, S; Lewis, J D; Lindgren, M; Liss, T M; Liu, J B; Liu, Y C; Litvintsev, D O; Lobban, O; Lockyer, N; Loken, J; Loreti, M; Lucchesi, D; Lukens, P; Lusin, S; Lyons, L; Lys, J; Madrak, R; Maeshima, K; Maksimovic, P; Malferrari, L; Mangano, M; Mariotti, M; Martignon, G; Martin, A; Matthews, J A J; Mayer, J; Mazzanti, P; McFarland, K S; McIntyre, P; McKigney, E; Menguzzato, M; Menzione, A; Mesropian, C; Meyer, A; Miao, T; Miller, R; Miller, J S; Minato, H; Miscetti, S; Mishina, M; Mitselmakher, G; Moggi, N; Moore, E; Moore, R; Morita, Y; Moulik, T; Mulhearn, M; Mukherjee, A; Muller, T; Munar, A; Murat, P; Murgia, S; Nachtman, J; Nagaslaev, V; Nahn, S; Nakada, H; Nakano, I; Nelson, C; Nelson, T; Neu, C; Neuberger, D; Newman-Holmes, C; Ngan, C-Y P; Niu, H; Nodulman, L; Nomerotski, A; Oh, S H; Oh, Y D; Ohmoto, T; Ohsugi, T; Oishi, R; Okusawa, T; Olsen, J; Orejudos, W; Pagliarone, C; Palmonari, F; Paoletti, R; Papadimitriou, V; Partos, D; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pescara, L; Phillips, T J; Piacentino, G; Pitts, K T; Pompos, A; Pondrom, L; Pope, G; Popovic, M; Prokoshin, F; Proudfoot, J; Ptohos, F; Pukhov, O; Punzi, G; Rakitine, A; Ratnikov, F; Reher, D; Reichold, A; Ribon, A; Riegler, W; Rimondi, F; Ristori, L; Riveline, M; Robertson, W J; Robinson, A; Rodrigo, T; Rolli, S; Rosenson, L; Roser, R; Rossin, R; Roy, A; Ruiz, A; Safonov, A; St Denis, R; Sakumoto, W K; Saltzberg, D; Sanchez, C; Sansoni, A; Santi, L; Sato, H; Savard, P; Schlabach, P; Schmidt, E E; Schmidt, M P; Schmitt, M; Scodellaro, L; Scott, A; Scribano, A; Segler, S; Seidel, S; Seiya, Y; Semenov, A; Semeria, F; Shah, T; Shapiro, M D; Shepard, P F; Shibayama, T; Shimojima, M; Shochet, M; Sidoti, A; Siegrist, J; Sill, A; Sinervo, P; Singh, P; Slaughter, A J; Sliwa, K; Smith, C; Snider, F D; Solodsky, A; Spalding, J; Speer, T; Sphicas, P; Spinella, F; Spiropulu, M; Spiegel, L; Steele, J; Stefanini, A; Strologas, J; Strumia, F; Stuart, D; Sumorok, K; Suzuki, T; Takano, T; Takashima, R; Takikawa, K; Tamburello, P; Tanaka, M; Tannenbaum, B; Tecchio, M; Tesarek, R; Teng, P K; Terashi, K; Tether, S; Thompson, A S; Thurman-Keup, R; Tipton, P; Tkaczyk, S; Toback, D; Tollefson, K; Tollestrup, A; Tonelli, D; Toyoda, H; Trischuk, W; de Troconiz, J F; Tseng, J; Turini, N; Ukegawa, F; Vaiciulis, T; Valls, J; Vejcik, S; Velev, G; Veramendi, G; Vidal, R; Vila, I; Vilar, R; Volobouev, I; von der Mey, M; Vucinic, D; Wagner, R G; Wagner, R L; Wallace, N B; Wan, Z; Wang, C; Wang, M J; Ward, B; Waschke, S; Watanabe, T; Waters, D; Watts, T; Webb, R; Wenzel, H; Wester, W C; Wicklund, A B; Wicklund, E; Wilkes, T; Williams, H H; Wilson, P; Winer, B L; Winn, D; Wolbers, S; Wolinski, D; Wolinski, J; Wolinski, S; Worm, S; Wu, X; Wyss, J; Yao, W; Yagil, A; Yeh, G P; Yoh, J; Yosef, C; Yoshida, T; Yu, I; Yu, S; Yu, Z; Zanetti, A; Zetti, F; Zucchelli, S

2002-01-28

We have performed a search for gluinos (g) and scalar quarks (q) in a data sample of 84 pb(-1) of pp collisions at square root[s] = 1.8 TeV, recorded by the Collider Detector at Fermilab. We investigate the final state of large missing transverse energy and three or more jets, a characteristic signature in R-parity-conserving supersymmetric models. The analysis has been performed "blind," in that the inspection of the signal region is made only after the predictions from standard model backgrounds have been calculated. Comparing the data with predictions of constrained supersymmetric models, we exclude gluino masses below 195 GeV/c2 (95% C.L.), independent of the squark mass. For the case m(q) approximately m(g), gluino masses below 300 GeV/c2 are excluded.

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.

Chemical characterization and prebiotic activity of fructo-oligosaccharides from Stevia rebaudiana (Bertoni) roots and in vitro adventitious root cultures.

PubMed

Sanches Lopes, Sheila Mara; Francisco, Mariane Grigio; Higashi, Bruna; de Almeida, Rafaela Takako Ribeiro; Krausová, Gabriela; Pilau, Eduardo Jorge; Gonçalves, José Eduardo; Gonçalves, Regina Aparecida Correia; Oliveira, Arildo José Braz de

2016-11-05

Stevia rebaudiana (Bertoni) is widely studied because of its foliar steviol glycosides. Fructan-type polysaccharides were recently isolated from its roots. Fructans are reserve carbohydrates that have important positive health effects and technological applications in the food industry. The objective of the present study was to isolate and characterize fructo-oligosaccharides (FOSs) from S. rebaudiana roots and in vitro adventitious root cultures and evaluate the potential prebiotic effect of these molecules. The in vitro adventitious root cultures were obtained using a roller bottle system. Chemical analyses (gas chromatography-mass spectrometry, (1)H nuclear magnetic resonance, and off-line electrospray ionization-mass spectrometry) revealed similar chemical properties of FOSs that were obtained from the different sources. The potential prebiotic effects of FOSs that were isolated from S. rebaudiana roots enhanced the growth of both bifidobacteria and lactobacilli, with strains specificity in their fermentation ability. Copyright © 2016 Elsevier Ltd. All rights reserved.

An in situ approach to detect tree root ecology: linking ground-penetrating radar imaging to isotope-derived water acquisition zones

PubMed Central

Isaac, Marney E; Anglaaere, Luke C N

2013-01-01

Tree root distribution and activity are determinants of belowground competition. However, studying root response to environmental and management conditions remains logistically challenging. Methodologically, nondestructive in situ tree root ecology analysis has lagged. In this study, we tested a nondestructive approach to determine tree coarse root architecture and function of a perennial tree crop, Theobroma cacao L., at two edaphically contrasting sites (sandstone and phyllite–granite derived soils) in Ghana, West Africa. We detected coarse root vertical distribution using ground-penetrating radar and root activity via soil water acquisition using isotopic matching of δ18O plant and soil signatures. Coarse roots were detected to a depth of 50 cm, however, intraspecifc coarse root vertical distribution was modified by edaphic conditions. Soil δ18O isotopic signature declined with depth, providing conditions for plant–soil δ18O isotopic matching. This pattern held only under sandstone conditions where water acquisition zones were identifiably narrow in the 10–20 cm depth but broader under phyllite–granite conditions, presumably due to resource patchiness. Detected coarse root count by depth and measured fine root density were strongly correlated as were detected coarse root count and identified water acquisition zones, thus validating root detection capability of ground-penetrating radar, but exclusively on sandstone soils. This approach was able to characterize trends between intraspecific root architecture and edaphic-dependent resource availability, however, limited by site conditions. This study successfully demonstrates a new approach for in situ root studies that moves beyond invasive point sampling to nondestructive detection of root architecture and function. We discuss the transfer of such an approach to answer root ecology questions in various tree-based landscapes. PMID:23762519

Isolation and identification of antibacterial compound from the leaves of Cassia auriculata.

PubMed

Senthilkumar, P K; Reetha, D

2011-09-01

Antimicrobial properties of medicinal plants and plant parts such as flowers, roots, fruits, seeds and oils are being used to cure some chronic and acute diseases throughout the world. In the present study, an attempt has been made to isolate and identify the antibacterial compound present in the leaves of the Cassia auriculata. A preliminary screening of antibacterial activity was carried out with fine different plant extracts viz., Aegle marmelos, Chloris Virgata, Clausena anisata, Feronia limonia and Cassia auriculata against different human pathogenic bacteriae such as Escherichia coil, Salmonella typhi, Proteus mirabilis and Klebsiella pneumoniae at different concentrations. Based on the results, the plant Cassia auriculata was selected as the efficient plant, which shows antibacterial activity against the tested organisms. Further compound responsible for its antibacterial activity was isolated and identified by IR spectrum, 1HNMR, 13CNMR and Mass spectrum studies, as oleanolic acid, which has the molecular formula of C30H48O3.

Tuning supersymmetric models at the LHC: a comparative analysis at two-loop level.

NASA Astrophysics Data System (ADS)

Ghilencea, D. M.; Lee, H. M.; Park, M.

2012-07-01

We provide a comparative study of the fine tuning amount (Δ) at the two-loop leading log level in supersymmetric models commonly used in SUSY searches at the LHC. These are the constrained MSSM (CMSSM), non-universal Higgs masses models (NUHM1, NUHM2), non-universal gaugino masses model (NUGM) and GUT related gaugino masses models (NUGMd). Two definitions of the fine tuning are used, the first (Δmax) measures maximal fine-tuning w.r.t. individual parameters while the second (Δ q ) adds their contribution in "quadrature". As a direct consequence of two theoretical constraints (the EW minimum conditions), fine tuning (Δ q ) emerges at the mathematical level as a suppressing factor (effective prior) of the averaged likelihood ( L ) under the priors, under the integral of the global probability of measuring the data (Bayesian evidence p( D)). For each model, there is little difference between Δ q , Δmax in the region allowed by the data, with similar behaviour as functions of the Higgs, gluino, stop mass or SUSY scale ( {m_{{SUSY}}} = {( {{m_{{overline t 1}}}{m_{{overline t 2}}}} )^{{{{1} / {2} .}}}} ) or dark matter and g - 2 constraints. The analysis has the advantage that by replacing any of these mass scales or constraints by their latest bounds one easily infers for each model the value of Δ q , Δmax or vice versa. For all models, minimal fine tuning is achieved for M higgs near 115 GeV with a Δ q ≈ Δmax ≈ 10 to 100 depending on the model, and in the CMSSM this is actually a global minimum. Due to a strong (≈ exponential) dependence of Δ on M higgs, for a Higgs mass near 125 GeV, the above values of Δ q ≈ Δmax increase to between 500 and 1000. Possible corrections to these values are briefly discussed.

[Concentrations of fine particulate matters and ultrafine particles and influenced factors during winter in an area of Beijing].

PubMed

Ni, Yang; Tu, Xing-ying; Zhu, Yi-dan; Guo, Xin-biao; Deng, Fu-rong

2014-06-18

To study the concentrations of fine particulate matters and ultrafine particles and influenced factors during winter in an area of Beijing. Real-time monitoring of particles' mass and number concentrations were conducted in an area of Beijing from February 7(th) to 27(th), 2013. At the same time, the meteorological data were also collected from the Beijing meteorological website. Differences of the particles' mass and number concentrations during different periods were analyzed using Mann-Whitney U test. Meanwhile, the influenced factors were also analyzed. The mean concentrations of fine particulate matters and ultrafine particles were (157.2 ± 142.8) μg/m³ and (25 018 ± 9 309) particles/cm³, respectively. The particles' number and mass concentrations in haze days were 1.27 times and 2.91 times higher than those in non-haze days, respectively. The mass concentrations of fine particulate matters in the self-monitoring site were higher than those in the nearest central monitoring sites, and the hourly-average concentrations of particles were significantly consistent with those at the commuter times. Meanwhile, the setting off of fireworks/firecrackers during the Spring Festival could lead to short-term increases of the particles' number and mass concentrations. When the wind speed was low and the related humidity was high, the concentrations of particulate matters were relatively high, and the mass concentrations of fine particulate matters were lagged about 1-2 d. The level of the particulate matters in this area was high. Heavy traffic, setting off of fireworks/firecrackers and meteorological factors may be some of the main factors affecting the concentrations of the particulate matters in this area. Among those factors, the effect of setting off of fireworks/firecrackers didn't last long and the effect of the meteorological factors had a hysteresis effect.

Identification and Quantitation of Various Inositols and O-methylinositols Present in Plant Roots Using Gas Chromatograpghy/Mass Spectrometry

USDA-ARS?s Scientific Manuscript database

Many inositols and O-methylinositols serve important roles in medicine and plant biology. A simple method was developed for the identification of these compounds in plant roots by extracting with 80% ethanol, derivatizing with trimethylsilyl imidazole, and analyzing by gas chromatography/mass spect...

Application of insoluble fibers in the fining of wine phenolics.

PubMed

Guerrero, Raúl F; Smith, Paul; Bindon, Keren A

2013-05-08

The application of animal-derived proteins as wine fining agents has been subject to increased regulation in recent years. As an alternative to protein-based fining agents, insoluble plant-derived fibers have the capacity to adsorb red wine tannins. Changes in red wine tannin were analyzed following application of fibers derived from apple and grape and protein-based fining agents. Other changes in wine composition, namely, color, monomeric phenolics, metals, and turbidity, were also determined. Wine tannin was maximally reduced by application of an apple pomace fiber and a grape pomace fiber (G4), removing 42 and 38%, respectively. Potassium caseinate maximally removed 19% of wine tannin, although applied at a lower dose. Fibers reduced anthocyanins, total phenolics, and wine color density, but changes in wine hue were minor. Proteins and apple fiber selectively removed high molecular mass phenolics, whereas grape fibers removed those of both high and low molecular mass. The results show that insoluble fibers may be considered as alternative fining agents for red wines.

Modelling the root system architecture of Poaceae. Can we simulate integrated traits from morphological parameters of growth and branching?

PubMed

Pagès, Loïc; Picon-Cochard, Catherine

2014-10-01

Our objective was to calibrate a model of the root system architecture on several Poaceae species and to assess its value to simulate several 'integrated' traits measured at the root system level: specific root length (SRL), maximum root depth and root mass. We used the model ArchiSimple, made up of sub-models that represent and combine the basic developmental processes, and an experiment on 13 perennial grassland Poaceae species grown in 1.5-m-deep containers and sampled at two different dates after planting (80 and 120 d). Model parameters were estimated almost independently using small samples of the root systems taken at both dates. The relationships obtained for calibration validated the sub-models, and showed species effects on the parameter values. The simulations of integrated traits were relatively correct for SRL and were good for root depth and root mass at the two dates. We obtained some systematic discrepancies that were related to the slight decline of root growth in the last period of the experiment. Because the model allowed correct predictions on a large set of Poaceae species without global fitting, we consider that it is a suitable tool for linking root traits at different organisation levels. © 2014 INRA. New Phytologist © 2014 New Phytologist Trust.

Fine-tuning of root elongation by ethylene: a tool to study dynamic structure–function relationships between root architecture and nitrate absorption

PubMed Central

Le Deunff, Erwan; Lecourt, Julien; Malagoli, Philippe

2016-01-01

Background Recently developed genetic and pharmacological approaches have been used to explore NO3−/ethylene signalling interactions and how the modifications in root architecture by pharmacological modulation of ethylene biosynthesis affect nitrate uptake. Key Results Structure–function studies combined with recent approaches to chemical genomics highlight the non-specificity of commonly used inhibitors of ethylene biosynthesis such as AVG (l-aminoethoxyvinylglycine). Indeed, AVG inhibits aminotransferases such as ACC synthase (ACS) and tryptophan aminotransferase (TAA) involved in ethylene and auxin biosynthesis but also some aminotransferases implied in nitrogen (N) metabolism. In this framework, it can be assumed that the products of nitrate assimilation and hormones may interact through a hub in carbon (C) and N metabolism to drive the root morphogenetic programme (RMP). Although ethylene/auxin interactions play a major role in cell division and elongation in root meristems, shaping of the root system depends also on energetic considerations. Based on this finding, the analysis is extended to nutrient ion–hormone interactions assuming a fractal or constructal model for root development. Conclusion Therefore, the tight control of root structure–function in the RMP may explain why over-expressing nitrate transporter genes to decouple structure–function relationships and improve nitrogen use efficiency (NUE) has been unsuccessful. PMID:27411681

Trickle-bed root culture bioreactor design and scale-up: growth, fluid-dynamics, and oxygen mass transfer.

PubMed

Ramakrishnan, Divakar; Curtis, Wayne R

2004-10-20

Trickle-bed root culture reactors are shown to achieve tissue concentrations as high as 36 g DW/L (752 g FW/L) at a scale of 14 L. Root growth rate in a 1.6-L reactor configuration with improved operational conditions is shown to be indistinguishable from the laboratory-scale benchmark, the shaker flask (mu=0.33 day(-1)). These results demonstrate that trickle-bed reactor systems can sustain tissue concentrations, growth rates and volumetric biomass productivities substantially higher than other reported bioreactor configurations. Mass transfer and fluid dynamics are characterized in trickle-bed root reactors to identify appropriate operating conditions and scale-up criteria. Root tissue respiration goes through a minimum with increasing liquid flow, which is qualitatively consistent with traditional trickle-bed performance. However, liquid hold-up is much higher than traditional trickle-beds and alternative correlations based on liquid hold-up per unit tissue mass are required to account for large changes in biomass volume fraction. Bioreactor characterization is sufficient to carry out preliminary design calculations that indicate scale-up feasibility to at least 10,000 liters.

Soil Fungi Respond More Strongly Than Fine Roots to Elevated CO2 in a Model Regenerating Longleaf Pine-Wiregrass Ecosystem

USDA-ARS?s Scientific Manuscript database

Increasing atmospheric CO2 will have significant effects on belowground processes which will affect forest structure and function. A model regenerating longleaf pine-wiregrass community [consisting of longleaf pine (Pinus palustris), wiregrass (Aristida stricta), sand post oak (Quescus margaretta),...

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

NASA Astrophysics Data System (ADS)

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

2009-12-01

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

A Functional Trait Approach for Evaluation of Agroforestry Species Adaptation Potentiel to Changing Climate

NASA Astrophysics Data System (ADS)

Munson, A. D.; Marone, D.; Olivier, A.

2017-12-01

Traditional agroforestry systems have been used for generations in the Sahel region of Africa to assure local food security. However, an understanding of the functional ecology of these systems is lacking, which would contribute to assessing both the provision of current ecological services, and the potential for adaptation to global change. We have studied five native tree and shrub species across a transect of different soil types in the semi-arid zone of the Niayes region of Senegal, to document changes in above and belowground traits in response to soil and land use change. Root traits in particular influence access to limiting resources such as water and nutrients. We studied fine root depth distribution and specific root length (SRL) with soil depth of Acacia raddiana, Balanites aegyptiaca, Euphorbia balsamifera, Faidherbia albida, Neocarya macrophylla, on three different soil textures for three systems (fallow, parkland and rangeland), in order to understand potential exploitation of soil resources and potential contribution of roots to soil carbon stocks at different depths. The maximum root biomass of four of the species (Acacia raddiana, Balanites aegyptiaca, Euphorbia balsamifera, Neocarya macrophylla) occurred in the 40-60 cm layer, where the two evergreen species (A. raddiana, N. macrophylla) developed the most biomass. Root biomass decreased for all species except F. albida, after 60 cm depth. The Mimosaceae species (A. raddiana, F. albida) developed the most root biomass within the 100 cm sampling depth. The maximum fine root biomass was found in fallow lands and clay soils. For all species, the highest SRL was observed during the hot dry season, in sandy or sandy loam soil. The SRL was lowest in the rainy season on clay soil. Evergreens had higher SRL than deciduous species, regardless of soil texture and growing season conditions. Parkland and rangelands exhibited higher SRL than fallow land, most likely due to higher soil fertility. Differences between evergreen and deciduous SRL relied on adaptive strategies that seem to be conditioned by season, soil and land use. We also examined intraspecific variability of above and belowground traits to assess plasticity in response to environment. Evergreen species showed more variability in response to soil and to seasonal changes in temperature and moisture.

Experimentally reduced root-microbe interactions reveal limited plasticity in functional root traits in Acer and Quercus.

PubMed

Lee, Mei-Ho; Comas, Louise H; Callahan, Hilary S

2014-02-01

Interactions between roots and soil microbes are critical components of below-ground ecology. It is essential to quantify the magnitude of root trait variation both among and within species, including variation due to plasticity. In addition to contextualizing the magnitude of plasticity relative to differences between species, studies of plasticity can ascertain if plasticity is predictable and whether an environmental factor elicits changes in traits that are functionally advantageous. To compare functional traits and trait plasticities in fine root tissues with natural and reduced levels of colonization by microbial symbionts, trimmed and surface-sterilized root segments of 2-year-old Acer rubrum and Quercus rubra seedlings were manipulated. Segments were then replanted into satellite pots filled with control or heat-treated soil, both originally derived from a natural forest. Mycorrhizal colonization was near zero in roots grown in heat-treated soil; roots grown in control soil matched the higher colonization levels observed in unmanipulated root samples collected from field locations. Between-treatment comparisons revealed negligible plasticity for root diameter, branching intensity and nitrogen concentration across both species. Roots from treated soils had decreased tissue density (approx. 10-20 %) and increased specific root length (approx. 10-30 %). In contrast, species differences were significant and greater than treatment effects in traits other than tissue density. Interspecific trait differences were also significant in field samples, which generally resembled greenhouse samples. The combination of experimental and field approaches was useful for contextualizing trait plasticity in comparison with inter- and intra-specific trait variation. Findings that root traits are largely species dependent, with the exception of root tissue density, are discussed in the context of current literature on root trait variation, interactions with symbionts and recent progress in standardization of methods for quantifying root traits.

Microbial decomposition of dead grassland roots and its influence on the carbon cycle under changing precipitation patterns

NASA Astrophysics Data System (ADS)

Becerra, C.; Schimel, J.

2013-12-01

Soil is the largest reservoir of organic carbon in terrestrial ecosystems and as such, represents a potential sink for carbon dioxide.The decomposition products of dead roots buried in the soil is a contributor to soil organic carbon. However, changing precipitation patterns may affect its fate by influencing the microbial community responsible for decomposing dead roots. To assess the impact of changing precipitation patterns, we constructed microcosms with grassland soil collected from the UCSB Sedgwick Reserve, an active and long-term research site, and dead roots from greenhouse-grown grass, Bromus diandrus. Microcosms were wetted continuously, every seven days, or every twenty days. Sets of microcosms were periodically deconstructed to assess the soil versus the roots-associated microbial community and its function. Differences in respiration rates of microcosms continuously wetted or wetted every 7 days versus microcosms wetted every 20 days existed for the first 70 days. After which, no differences in respiration rates were seen with microcosms containing roots and the no roots control. Relatedly, after a 70% roots mass loss by day 50, there was no difference in the respiration rate of microcosms containing roots and the no roots control. More than half of the roots mass loss had occurred by 30 days. By the end of the incubation period, the roots mass loss in continuously wet and 7-day wetted microcosms were over 80% compared to 67% for the microcosms wetted every 20 days. Microbial biomass in the soil were constant over time and showed no difference in treatment except with the no roots control during the first half of the incubation period. Hydrolytic enzyme activities (β-1,4-glucosidase; α-1,4-glucosidase; β-1,4-xylosidase; β-1,4-cellobiosidase) on the roots versus the soil attached to the roots were over an order greater and decreased faster with the exception of N-acetyl-glucosaminidase and acid phosphatase. Oxidative enzyme activities (phenol oxidase and peroxidase) on the roots versus the soil were also an order of magnitude greater, however the activities were constant over time regardless of the treatment, whereas the activities in the soil increased then decreased after 50 days. Our results suggest that the frequency of precipitation affects early root decomposition and long-term soil carbon storage of dead roots relatively unaffected by changing precipitation patterns.

Can Wet Rocky Granular Flows Become Debris Flows Due to Fine Sediment Production by Abrasion?

NASA Astrophysics Data System (ADS)

Arabnia, O.; Sklar, L. S.; Bianchi, G.; Mclaughlin, M. K.

2015-12-01

Debris flows are rapid mass movements in which elevated pore pressures are sustained by a viscous fluid matrix with high concentrations of fine sediments. Debris flows may form from coarse-grained wet granular flows as fine sediments are entrained from hillslope and channel material. Here we investigate whether abrasion of the rocks within a granular flow can produce sufficient fine sediments to create debris flows. To test this hypothesis experimentally, we used a set of 4 rotating drums ranging from 0.2 to 4.0 m diameter. Each drum has vanes along the boundary ensure shearing within the flow. Shear rate was varied by changing drum rotational velocity to maintain a constant Froude Number across drums. Initial runs used angular clasts of granodiorite with a tensile strength of 7.6 MPa, with well-sorted coarse particle size distributions linearly scaled with drum radius. The fluid was initially clear water, which rapidly acquired fine-grained wear products. After each 250 m tangential distance, we measured the particle size distributions, and then returned all water and sediment to the drums for subsequent runs. We calculate particle wear rates using statistics of size and mass distributions, and by fitting the Sternberg equation to the rate of mass loss from the size fraction > 2mm. Abundant fine sediments were produced in the experiments, but very little change in the median grain size was detected. This appears to be due to clast rounding, as evidenced by a decrease in the number of stable equilibrium resting points. We find that the growth in the fine sediment concentration in the fluid scales with unit drum power. This relationship can be used to estimate fine sediment production rates in the field. We explore this approach at Inyo Creek, a steep catchment in the Sierra Nevada, California. There, a significant debris flow occurred in July 2013, which originated as a coarse-grained wet granular flow. We use surveys to estimate flow depth and velocity where super-elevation occurred, to calculate a unit power of 4.5 KW/m2. From this we predict that 14% of the coarse mass is converted to fine sediment by abrasion per km. At that rate, the increase in fines concentration may have been sufficient to cause a wet granular flow to evolve into a debris flow within the first 1 km of its > 4km travel distance.

Supernatural MSSM

NASA Astrophysics Data System (ADS)

Du, Guangle; Li, Tianjun; Nanopoulos, D. V.; Raza, Shabbar

2015-07-01

We point out that the electroweak fine-tuning problem in the supersymmetric standard models (SSMs) is mainly due to the high energy definition of the fine-tuning measure. We propose supernatural supersymmetry which has an order one high energy fine-tuning measure automatically. The key point is that all the mass parameters in the SSMs arise from a single supersymmetry breaking parameter. In this paper, we show that there is no supersymmetry electroweak fine-tuning problem explicitly in the minimal SSM (MSSM) with no-scale supergravity and Giudice-Masiero mechanism. We demonstrate that the Z -boson mass, the supersymmetric Higgs mixing parameter μ at the unification scale, and the sparticle spectrum can be given as functions of the universal gaugino mass M1 /2. Because the light stau is the lightest supersymmetric particle (LSP) in the no-scale MSSM, to preserve R parity, we introduce a non-thermally generated axino as the LSP dark matter candidate. We estimate the lifetime of the light stau by calculating its two-body and three-body decays to the LSP axino for several values of axion decay constant fa, and find that the light stau has a lifetime ττ ˜1 in [10-4,100 ] s for an fa range [109,1012] GeV . We show that our next to the LSP stau solutions are consistent with all the current experimental constraints, including the sparticle mass bounds, B-physics bounds, Higgs mass, cosmological bounds, and the bounds on long-lived charged particles at the LHC.

Characterizing root system characteristics with Electrical resistivity Tomography: a virtual rhizotron simulation

NASA Astrophysics Data System (ADS)

Rao, Sathyanarayan; Ehosioke, Solomon; Lesparre, Nolwenn; Nguyen, Frédéric; Javaux, Mathieu

2017-04-01

Electrical Resistivity Tomography (ERT) is more and more used for monitoring soil water content in a cropped soil. Yet, the impact of roots on the signal is often neglected and a topic of controversy. In several studies related to soil-root system, it has been showed that the measured root mass density statistically correlates with the electrical conductivity (EC) data obtained from ERT. In addition, some studies suggest that some roots are more electrically conductive than soil for most water content. Thus, higher EC of roots suggest that it might have a measurable impact on ERT signals. In this work, virtual rhizotrons are simulated using the software package called R-SWMS that solves water and solute transport in plant root-soil system, including root growth. The distribution of water content obtained from R-SWMS simulation is converted into EC data using pedo-physical models. The electrical properties of roots and rhizosphere are explicitly included in the EC data to form a conductivity map (CM) with a very detailed spatial resolution. Forward ERT simulations is then carried out for CM generated for various root architectures and soil conditions to study the impact of roots on ERT forward (current and voltage patterns) and inverse solutions. It is demonstrated that under typical injection schemes with lateral electrodes, root system is hardly measurable. However, it is showed that adding electrodes and constraints on the ERT inversion based on root architecture help quantifying root system mass and extent.

Arabidopsis pdr2 reveals a phosphate-sensitive checkpoint in root development.

PubMed

Ticconi, Carla A; Delatorre, Carla A; Lahner, Brett; Salt, David E; Abel, Steffen

2004-03-01

Plants have evolved complex strategies to maintain phosphate (Pi) homeostasis and to maximize Pi acquisition when the macronutrient is limiting. Adjustment of root system architecture via changes in meristem initiation and activity is integral to the acclimation process. However, the mechanisms that monitor external Pi status and interpret the nutritional signal remain to be elucidated. Here, we present evidence that the Pi deficiency response, pdr2, mutation disrupts local Pi sensing. The sensitivity and amplitude of metabolic Pi-starvation responses, such as Pi-responsive gene expression or accumulation of anthocyanins and starch, are enhanced in pdr2 seedlings. However, the most conspicuous alteration of pdr2 is a conditional short-root phenotype that is specific for Pi deficiency and caused by selective inhibition of root cell division followed by cell death below a threshold concentration of about 0.1 mm external Pi. Measurements of general Pi uptake and of total phosphorus (P) in root tips exclude a defect in high-affinity Pi acquisition. Rescue of root meristem activity in Pi-starved pdr2 by phosphite (Phi), a non-metabolizable Pi analog, and divided-root experiments suggest that pdr2 disrupts sensing of low external Pi availability. Thus, PDR2 is proposed to function at a Pi-sensitive checkpoint in root development, which monitors environmental Pi status, maintains and fine-tunes meristematic activity, and finally adjusts root system architecture to maximize Pi acquisition.

Intensive field phenotyping of maize (Zea mays L.) root crowns identifies phenes and phene integration associated with plant growth and nitrogen acquisition

PubMed Central

York, Larry M.; Lynch, Jonathan P.

2015-01-01

Root architecture is an important regulator of nitrogen (N) acquisition. Existing methods to phenotype the root architecture of cereal crops are generally limited to seedlings or to the outer roots of mature root crowns. The functional integration of root phenes is poorly understood. In this study, intensive phenotyping of mature root crowns of maize was conducted to discover phenes and phene modules related to N acquisition. Twelve maize genotypes were grown under replete and deficient N regimes in the field in South Africa and eight in the USA. An image was captured for every whorl of nodal roots in each crown. Custom software was used to measure root phenes including nodal occupancy, angle, diameter, distance to branching, lateral branching, and lateral length. Variation existed for all root phenes within maize root crowns. Size-related phenes such as diameter and number were substantially influenced by nodal position, while angle, lateral density, and distance to branching were not. Greater distance to branching, the length from the shoot to the emergence of laterals, is proposed to be a novel phene state that minimizes placing roots in already explored soil. Root phenes from both older and younger whorls of nodal roots contributed to variation in shoot mass and N uptake. The additive integration of root phenes accounted for 70% of the variation observed in shoot mass in low N soil. These results demonstrate the utility of intensive phenotyping of mature root systems, as well as the importance of phene integration in soil resource acquisition. PMID:26041317

Defense Coastal/Estuarine Research Program (DCERP) Baseline Monitoring Plan

DTIC Science & Technology

2007-09-19

climatological stress (e.g., temperature, drought) and shorter-term air pollutant stress (oxidants and metals ). Heavy metals of fine PM have been...speciation of the fine and coarse PM fractions will allow distinction between different PM sources such as wind blown soil dust, including dust...emitting 12% of the total PM2.5 mass (U.S. EPA, 2004b). Source apportionment modeling of PM2.5 mass concentrations from 24 Speciation Defense Coastal

Partially natural two Higgs doublet models

DOE PAGES

Draper, Patrick; Haber, Howard E.; Ruderman, Joshua T.

2016-06-21

It is possible that the electroweak scale is low due to the fine-tuning of microscopic parameters, which can result from selection effects. The experimental discovery of new light fundamental scalars other than the Standard Model Higgs boson would seem to disfavor this possibility, since generically such states imply parametrically worse fine-tuning with no compelling connection to selection effects. We discuss counterexamples where the Higgs boson is light because of fine-tuning, and a second scalar doublet is light because a discrete symmetry relates its mass to the mass of the Standard Model Higgs boson. Our examples require new vectorlike fermions atmore » the electroweak scale, and the models possess a rich electroweak vacuum structure. Furthermore, the mechanism that we discuss does not protect a small CP-odd Higgs mass in split or high-scale supersymmetry-breaking scenarios of the MSSM due to an incompatibility between the discrete symmetries and holomorphy.« less

Fine-needle aspiration by vacuum tubes.

PubMed

Holmquist, N D

1989-07-01

Fine-needle aspiration of subcutaneous masses, accepted in many parts of Europe and the Americas as a routine diagnostic technique, employs a syringe holder to facilitate the creation of a vacuum to withdraw cells. This investigation demonstrates that a vacuum tube used in venipuncture can be used to supply the negative pressure to suck cells into the needle. This apparatus is more readily available than a syringe holder in hospitals and clinics, and particularly provides the operator with a more dexterous approach to the mass because the fingers holding the needle can be much closer to the mass being immobilized by the other hand.