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Mary K Firestone - One of the best experts on this subject based on the ideXlab platform.
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seasonal dynamics of microbial Community Composition and function in oak canopy and open grassland soils
Microbial Ecology, 2006Co-Authors: M P Waldrop, Mary K FirestoneAbstract:Soil microbial communities are closely associated with aboveground plant communities, with multiple potential drivers of this relationship. Plants can affect available soil carbon, temperature, and water content, which each have the potential to affect microbial Community Composition and function. These same variables change seasonally, and thus plant control on microbial Community Composition may be modulated or overshadowed by annual climatic patterns. We examined microbial Community Composition, C cycling processes, and environmental data in California annual grassland soils from beneath oak canopies and in open grassland areas to distinguish factors controlling microbial Community Composition and function seasonally and in association with the two plant overstory communities. Every 3 months for up to 2 years, we monitored microbial Community Composition using phospholipid fatty acid (PLFA) analysis, microbial biomass, respiration rates, microbial enzyme activities, and the activity of microbial groups using isotope labeling of PLFA biomarkers (13C-PLFA). Distinct microbial communities were associated with oak canopy soils and open grassland soils and microbial communities displayed seasonal patterns from year to year. The effects of plant species and seasonal climate on microbial Community Composition were similar in magnitude. In this Mediterranean ecosystem, plant control of microbial Community Composition was primarily due to effects on soil water content, whereas the changes in microbial Community Composition seasonally appeared to be due, in large part, to soil temperature. Available soil carbon was not a significant control on microbial Community Composition. Microbial Community Composition (PLFA) and 13C-PLFA ordination values were strongly related to intra-annual variability in soil enzyme activities and soil respiration, but microbial biomass was not. In this Mediterranean climate, soil microclimate appeared to be the master variable controlling microbial Community Composition and function.
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linking microbial Community Composition and soil processes in a california annual grassland and mixed conifer forest
Biogeochemistry, 2005Co-Authors: Teri C Balser, Mary K FirestoneAbstract:To investigate the potential role of microbial Community Composition in soil carbon and nitrogen cycling, we transplanted soil cores between a grassland and a conifer ecosystem in the Sierra Nevada California and measured soil process rates (N-mineralization, nitrous oxide and carbondioxide flux, nitrification potential), soil water and temperature, and microbial Community parameters (PLFA and substrate utilization profiles) over a 2 year period. Our goal was to assess whether microbial Community Composition could be related to soil process rates independent of soil temperature and water content. We performed multiple regression analyses using microbial Community parameters and soil water and temperature as X-variables and soil process rates and inorganic N concentrations as Y-variables. We found that field soil temperature had the strongest relationship with CO2 production and soil NH4+ concentration, while microbial Community characteristics correlated with N2O production, nitrification potential, gross N-mineralization, and soil NO3− concentration, independent of environmentalcontrollers. We observed a relationship between specific components of the microbial Community (as determined by PLFA) and soil processes,particularly processes tightly linked to microbial phylogeny (e.g. nitrification). The most apparent change in microbial Community Composition in response to the 2 year transplant was a change in relative abundance of fungi (there was only one significant change in PLFA biomarkers for bacteria during 2 years). The relationship between microbial Community Composition and soil processes suggests that prediction of ecosystem response to environmental change may be improved by recognizing and accounting for changes in microbial Community Composition and physiological ecology.
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linking microbial Community Composition to function in a tropical soil
Soil Biology & Biochemistry, 2000Co-Authors: Mark P Waldrop, Teri C Balser, Mary K FirestoneAbstract:Abstract If changes in the Composition of the soil microbial Community alter the physiological capacity of the Community then such changes may have ecosystem consequences. We examined the relationships among Community Composition (PLFA), microbial biomass (CFDE), substrate utilization profiles (BIOLOG), lignocellulose degrading enzyme activities (β-glucosidase, cellobiohydrolase, β-xylosidase, phenol oxidase, peroxidase), and nutrient releasing enzyme activities (phosphatase, sulphatase) in a Tropeptic Haplustol soil. The soils supported a tropical forest and pineapple plantations of varying ages that were at different stages within the management cycle. Conversion from forest to agriculture significantly decreased %C and %N of the soil by 50–55%, microbial biomass by 75%, β-glucosidase by 54%, sulphatase activity by 85%, decreased Ca, Mg, and Mn availability, and produced Compositionally and functionally distinct microbial communities. Total enzyme activities were generally correlated with %C, %N, microbial biomass and, occasionally with Community Composition. We calculated the specific activities of the enzymes assayed (enzyme activity per unit microbial biomass C) in order to normalize activity to the size of the microbial Community. Values for enzyme specific activities were more highly correlated with Community Composition than were total enzyme activities. In addition, BIOLOG was not correlated with Community Composition or enzyme activities. Enzyme activities and specific activities may provide a useful linkage between microbial Community Composition and carbon processing.
Nicholas P Rosenstock - One of the best experts on this subject based on the ideXlab platform.
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carbon sequestration and Community Composition of ectomycorrhizal fungi across a geothermal warming gradient in an icelandic spruce forest
Fungal Ecology, 2019Co-Authors: Nicholas P Rosenstock, Magnus Ellstrom, Edda Sigurdis Oddsdottir, Bjarni D Sigurdsson, Hakan WallanderAbstract:Abstract Soil warming (0–5.5 °C above controls) effects on ectomycorrhizal growth, carbon sequestration and Community Composition were examined in a Picea sitchensis forest spanning a geothermal gradient in Iceland. Fungal communities were assayed with sand-filled ingrowth meshbags incubated in the soil for 5 months. Meshbags amended with compost made from maize leaves (a C4 plant enriched in 13C) were incubated for 5 or 12 months and used to estimate C sequestration by the fungal Community. Despite increases in tree growth, moderate warming only slightly reduced or had no effect on mycelial growth and had no effect on fungal carbon sequestration or overall ectomycorrhizal Community Composition. Warming was associated with increased abundance of ascomycetes, particularly pyronemataceous ectomycorrhizal fungi, and altered saprotrophic Community Composition. Increased nitrate availability and root turnover may explain the lack of a positive ectomycorrhizal growth response to increased tree growth and observed shifts in Community Composition with warming.
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long term agricultural fertilization alters arbuscular mycorrhizal fungal Community Composition and barley hordeum vulgare mycorrhizal carbon and phosphorus exchange
New Phytologist, 2017Co-Authors: Alwyn Williams, Nicholas P Rosenstock, Lokeshwaran Manoharan, Pal Axel Olsson, Katarina HedlundAbstract:Agricultural fertilization significantly affects arbuscular mycorrhizal fungal (AMF) Community Composition. However, the functional implications of Community shifts are unknown, limiting understanding of the role of AMF in agriculture. We assessed AMF Community Composition at four sites managed under the same nitrogen (N) and phosphorus (P) fertilizer regimes for 55 yr. We also established a glasshouse experiment with the same soils to investigate AMF–barley (Hordeum vulgare) nutrient exchange, using carbon (13C) and 33P isotopic labelling. N fertilization affected AMF Community Composition, reducing diversity; P had no effect. In the glasshouse, AMF contribution to plant P declined with P fertilization, but was unaffected by N. Barley C allocation to AMF also declined with P fertilization. As N fertilization increased, C allocation to AMF per unit of P exchanged increased. This occurred with and without P fertilization, and was concomitant with reduced barley biomass. AMF Community Composition showed no relationship with glasshouse experiment results. The results indicate that plants can reduce C allocation to AMF in response to P fertilization. Under N fertilization, plants allocate an increasing amount of C to AMF and receive relatively less P. This suggests an alteration in the terms of P–C exchange under N fertilization regardless of soil P status.
Francois Buscot - One of the best experts on this subject based on the ideXlab platform.
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forest age and plant species Composition determine the soil fungal Community Composition in a chinese subtropical forest
PLOS ONE, 2013Co-Authors: Tesfaye Wubet, Stefan Trogisch, Sabine Both, Thomas Scholten, Helge Bruelheide, Francois BuscotAbstract:Fungal diversity and Community Composition are mainly related to soil and vegetation factors. However, the relative contribution of the different drivers remains largely unexplored, especially in subtropical forest ecosystems. We studied the fungal diversity and Community Composition of soils sampled from 12 comparative study plots representing three forest age classes (Young: 10–40 yrs; Medium: 40–80 yrs; Old: ≥80 yrs) in Gutianshan National Nature Reserve in South-eastern China. Soil fungal communities were assessed employing ITS rDNA pyrotag sequencing. Members of Basidiomycota and Ascomycota dominated the fungal Community, with 22 putative ectomycorrhizal fungal families, where Russulaceae and Thelephoraceae were the most abundant taxa. Analysis of similarity showed that the fungal Community Composition significantly differed among the three forest age classes. Forest age class, elevation of the study plots, and soil organic carbon (SOC) were the most important factors shaping the fungal Community Composition. We found a significant correlation between plant and fungal communities at different taxonomic and functional group levels, including a strong relationship between ectomycorrhizal fungal and non-ectomycorrhizal plant communities. Our results suggest that in subtropical forests, plant species Community Composition is the main driver of the soil fungal diversity and Community Composition.
Lubos Polerecky - One of the best experts on this subject based on the ideXlab platform.
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spatial patterns and links between microbial Community Composition and function in cyanobacterial mats
Frontiers in Microbiology, 2014Co-Authors: Alban Ramette, Mohammad A A Alnajjar, Michael Kuhl, Waleed Hamza, Judith M Klatt, Lubos PolereckyAbstract:We imaged reflectance and variable fluorescence in 25 cyanobacterial mats from four distant sites around the globe to assess, at different scales of resolution, spatial variabilities in the physiological parameters characterizing their photosynthetic capacity, including the absorptivity by chlorophyll a (Achl), maximum quantum yield of photosynthesis (Ymax), and light acclimation irradiance (Ik). Generally, these parameters significantly varied within individual mats on a sub-millimeter scale, with about 2-fold higher variability in the vertical than in the horizontal direction. The average vertical profiles of Ymax and Ik decreased with depth in the mat, while Achl exhibited a sub-surface maximum. The within-mat variability was comparable to, but often larger than, the between-sites variability, whereas the within-site variabilities (i.e., between samples from the same site) were generally lowest. When compared based on averaged values of their photosynthetic parameters, mats clustered according to their site of origin. Similar clustering was found when the Community Composition of the mats' cyanobacterial layers were compared by automated ribosomal intergenic spacer analysis (ARISA), indicating a significant link between the microbial Community Composition and function. Although this link is likely the result of Community adaptation to the prevailing site-specific environmental conditions, our present data is insufficient to identify the main factors determining these patterns. Nevertheless, this study demonstrates that the spatial variability in the photosynthetic capacity and light acclimation of benthic phototrophic microbial communities is at least as large on a sub-millimeter scale as it is on a global scale, and suggests that this pattern of variability scaling is similar for the microbial Community Composition.
Katarina Hedlund - One of the best experts on this subject based on the ideXlab platform.
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long term agricultural fertilization alters arbuscular mycorrhizal fungal Community Composition and barley hordeum vulgare mycorrhizal carbon and phosphorus exchange
New Phytologist, 2017Co-Authors: Alwyn Williams, Nicholas P Rosenstock, Lokeshwaran Manoharan, Pal Axel Olsson, Katarina HedlundAbstract:Agricultural fertilization significantly affects arbuscular mycorrhizal fungal (AMF) Community Composition. However, the functional implications of Community shifts are unknown, limiting understanding of the role of AMF in agriculture. We assessed AMF Community Composition at four sites managed under the same nitrogen (N) and phosphorus (P) fertilizer regimes for 55 yr. We also established a glasshouse experiment with the same soils to investigate AMF–barley (Hordeum vulgare) nutrient exchange, using carbon (13C) and 33P isotopic labelling. N fertilization affected AMF Community Composition, reducing diversity; P had no effect. In the glasshouse, AMF contribution to plant P declined with P fertilization, but was unaffected by N. Barley C allocation to AMF also declined with P fertilization. As N fertilization increased, C allocation to AMF per unit of P exchanged increased. This occurred with and without P fertilization, and was concomitant with reduced barley biomass. AMF Community Composition showed no relationship with glasshouse experiment results. The results indicate that plants can reduce C allocation to AMF in response to P fertilization. Under N fertilization, plants allocate an increasing amount of C to AMF and receive relatively less P. This suggests an alteration in the terms of P–C exchange under N fertilization regardless of soil P status.
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influences of space soil nematodes and plants on microbial Community Composition of chalk grassland soils
Environmental Microbiology, 2009Co-Authors: Etienne Yergeau, Martijn T Bezemer, Katarina Hedlund, Simon R Mortimer, George A Kowalchuk, Wim H Van Der PuttenAbstract:Microbial communities respond to a variety of environmental factors related to resources (e.g. plant and soil organic matter), habitat (e.g. soil characteristics) and predation (e.g. nematodes, protozoa and viruses). However, the relative contribution of these factors on microbial Community Composition is poorly understood. Here, we sampled soils from 30 chalk grassland fields located in three different chalk hill ridges of Southern England, using a spatially explicit sampling scheme. We assessed microbial communities via phospholipid fatty acid (PLFA) analyses and PCR-denaturing gradient gel electrophoresis (DGGE) and measured soil characteristics, as well as nematode and plant Community Composition. The relative influences of space, soil, vegetation and nematodes on soil microorganisms were contrasted using variation partitioning and path analysis. Results indicate that soil characteristics and plant Community Composition, representing habitat and resources, shape soil microbial Community Composition, whereas the influence of nematodes, a potential predation factor, appears to be relatively small. Spatial variation in microbial Community structure was detected at broad (between fields) and fine (within fields) scales, suggesting that microbial communities exhibit biogeographic patterns at different scales. Although our analysis included several relevant explanatory data sets, a large part of the variation in microbial communities remained unexplained (up to 92% in some analyses). However, in several analyses, significant parts of the variation in microbial Community structure could be explained. The results of this study contribute to our understanding of the relative importance of different environmental and spatial factors in driving the Composition of soil-borne microbial communities.