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Ashish A Malik - One of the best experts on this subject based on the ideXlab platform.
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defining trait based microbial strategies with consequences for soil Carbon Cycling under climate change
The ISME Journal, 2020Co-Authors: Ashish A Malik, Jennifer B H Martiny, Eoin L Brodie, Adam C Martiny, Kathleen K Treseder, Steven D AllisonAbstract:Microorganisms are critical in terrestrial Carbon Cycling because their growth, activity and interactions with the environment largely control the fate of recent plant Carbon inputs as well as protected soil organic Carbon [1, 2]. Soil Carbon stocks reflect a balance between microbial decomposition of organic Carbon and stabilisation of microbial assimilated Carbon. The balance can shift under altered environmental conditions [3], and new research suggests that knowledge of microbial physiology may be critical for projecting changes in soil Carbon and improving the prognosis of climate change feedbacks [4–7]. Still, predicting the ecosystem implications of microbial processes remains a challenge. Here we argue that this challenge can be met by identifying microbial life history strategies based on an organism’s phenotypic characteristics, or traits, and representing these strategies in ecosystem models. What are the key microbial traits for soil Carbon Cycling under environmental change? Microbial growth and survival in soil are impacted by multiple traits that determine responses to varying resource availability and fluctuating abiotic conditions [8]. Cellular maintenance activities (those that do not produce growth) include production of extracellular enzymes to degrade and acquire resources, biomolecular repair mechanisms, maintenance of cellular integrity, osmotic balance, defence, antagonism, cell signalling and motility [9–11]. It is conceivable that microbial investment into maintenance activities would be generally high in soils, with their highly heterogeneous and temporally variable resource distribution and stressful abiotic conditions like extremes of moisture, temperature, pH and salinity [12, 13]. Selective pressures in suboptimal environmental conditions could lead to greater cellular-level physiological allocation to maintenance relative to growth traits (Fig. 1) thereby impacting soil Carbon Cycling processes. Open in a separate window Fig. 1 Schematic showing cellular C flux that includes depolymerisation, substrate uptake, assimilation, dissimilation, biomass synthesis and non-growth production. Extracellular enzyme production represents investment in resource acquisition, stress protein production is linked to stress tolerance mechanisms, and biomass production reflects higher growth yield. Forked arrows signify metabolic points where hypothesised tradeoffs in traits might occur. The expected empirical relationships among the key traits are also shown
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defining trait based microbial strategies with consequences for soil Carbon Cycling under climate change
bioRxiv, 2018Co-Authors: Ashish A Malik, Jennifer B H Martiny, Eoin L Brodie, Adam C Martiny, Kathleen K Treseder, Steven D AllisonAbstract:Microorganisms are critical in terrestrial Carbon Cycling because their growth, activity and interactions with the environment largely control the fate of recent plant Carbon inputs, as well as the stability of assimilated Carbon. Soil Carbon stocks reflect a balance between microbial decomposition and stabilization of organic Carbon. The balance can shift under altered environmental conditions, and new research suggests that knowledge of microbial physiology may be critical for projecting changes in soil Carbon and improving the prognosis of climate change feedbacks. Still, predicting the ecosystem implications of microbial processes remains a challenge. Here we argue that this challenge can be met by identifying microbial life history strategies based on an organism9s phenotypic characteristics, or traits, and representing these strategies in models simulating different environmental conditions. By adapting several theories from macroecology, we define microbial high yield (Y), resource acquisition (A), and stress tolerator (S) strategies based on key traits that are linked to organismal fitness. Our Y-A-S framework can guide new empirical and modelling studies on the mechanisms driving soil Carbon fluxes. By linking population-level response traits to community and ecosystem processes, our life history theory can improve predictive understanding of soil C responses to future climatic change.
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land use driven change in soil ph affects microbial Carbon Cycling processes
Nature Communications, 2018Co-Authors: Ashish A Malik, Somak Chowdhury, Jeremy Puissant, Nico Jehmlich, Kate M Buckeridge, Tim Goodall, Hyun S Gweon, Jodey Peyton, Kelly E Mason, Maaike Van AgtmaalAbstract:Soil microorganisms act as gatekeepers for soil–atmosphere Carbon exchange by balancing the accumulation and release of soil organic matter. However, poor understanding of the mechanisms responsible hinders the development of effective land management strategies to enhance soil Carbon storage. Here we empirically test the link between microbial ecophysiological traits and topsoil Carbon content across geographically distributed soils and land use contrasts. We discovered distinct pH controls on microbial mechanisms of Carbon accumulation. Land use intensification in low-pH soils that increased the pH above a threshold (~6.2) leads to Carbon loss through increased decomposition, following alleviation of acid retardation of microbial growth. However, loss of Carbon with intensification in near-neutral pH soils was linked to decreased microbial biomass and reduced growth efficiency that was, in turn, related to trade-offs with stress alleviation and resource acquisition. Thus, less-intensive management practices in near-neutral pH soils have more potential for Carbon storage through increased microbial growth efficiency, whereas in acidic soils, microbial growth is a bigger constraint on decomposition rates.
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soil fungal bacterial ratios are linked to altered Carbon Cycling
Frontiers in Microbiology, 2016Co-Authors: Ashish A Malik, Somak Chowdhury, Veronika Schlager, Anna Oliver, Jeremy Puissant, Perla Griselle Mellado Vazquez, Nico Jehmlich, Martin Von Bergen, Robert I Griffiths, Gerd GleixnerAbstract:Despite several lines of observational evidence, there is a lack of consensus on whether higher fungal:bacterial (F:B) ratios directly cause higher soil Carbon (C) storage. We employed RNA sequencing, protein profiling and isotope tracer techniques to evaluate whether differing F:B ratios are associated with differences in C storage. A mesocosm 13C labeled foliar litter decomposition experiment was performed in two soils that were similar in their physico-chemical properties but differed in microbial community structure, specifically their F:B ratio (determined by PLFA analyses, RNA sequencing and protein profiling; all three corroborating each other). Following litter addition, we observed a consistent increase in abundance of fungal phyla; and greater increases in the fungal dominated soil; implicating the role of fungi in litter decomposition. Litter derived 13C in respired CO2 was consistently lower, and residual 13C in bulk SOM was higher in high F:B soil demonstrating greater C storage potential in the fungal:bacterial dominated soil. We conclude that in this soil system, the increased abundance of fungi in both soils and the altered C Cycling patterns in the fungal:bacterial dominated soils highlight the significant role of fungi in litter decomposition and indicate that F:B ratios are linked to higher C storage potential.
Adam J Vanbergen - One of the best experts on this subject based on the ideXlab platform.
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Soil biota, Carbon Cycling and crop plant biomass responses to biochar in a temperate mesocosm experiment
Plant and Soil, 2019Co-Authors: Sarah A. Mccormack, David W. Hopkins, M. Glória Pereira, Richard D Bardgett, Nick Ostle, Adam J VanbergenAbstract:Background and aimsBiochar addition to soil is a Carbon capture and storage option with potential to mitigate rising atmospheric CO_2 concentrations, yet the consequences for soil organisms and linked ecosystem processes are inconsistent or unknown. We tested biochar impact on soil biodiversity, ecosystem functions, and their interactions, in temperate agricultural soils.MethodsWe performed a 27-month factorial experiment to determine effects of biochar, soil texture, and crop species treatments on microbial biomass (PFLA), soil invertebrate density, crop biomass and ecosystem CO_2 flux in plant-soil mesocosms.ResultsOverall soil microbial biomass, microarthropod abundance and crop biomass were unaffected by biochar, although there was an increase in fungal-bacterial ratio and a positive relationship between the 16:1ω5 fatty acid marker of AMF mass and collembolan density in the biochar-treated mesocosms. Ecosystem CO_2 fluxes were unaffected by biochar, but soil Carbon content of biochar-treated mesocosms was significantly lower, signifying a possible movement/loss of biochar or priming effect.ConclusionsCompared to soil texture and crop type, biochar had minimal impact on soil biota, crop production and Carbon Cycling. Future research should examine subtler effects of biochar on biotic regulation of ecosystem production and if the apparent robustness to biochar weakens over greater time spans or in combination with other ecological perturbations.
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soil biota Carbon Cycling and crop plant biomass responses to biochar in a temperate mesocosm experiment
Plant and Soil, 2019Co-Authors: Sarah A. Mccormack, David W. Hopkins, Richard D Bardgett, Nick Ostle, Gloria M Pereira, Adam J VanbergenAbstract:Biochar addition to soil is a Carbon capture and storage option with potential to mitigate rising atmospheric CO2 concentrations, yet the consequences for soil organisms and linked ecosystem processes are inconsistent or unknown. We tested biochar impact on soil biodiversity, ecosystem functions, and their interactions, in temperate agricultural soils. We performed a 27-month factorial experiment to determine effects of biochar, soil texture, and crop species treatments on microbial biomass (PFLA), soil invertebrate density, crop biomass and ecosystem CO2 flux in plant-soil mesocosms. Overall soil microbial biomass, microarthropod abundance and crop biomass were unaffected by biochar, although there was an increase in fungal-bacterial ratio and a positive relationship between the 16:1ω5 fatty acid marker of AMF mass and collembolan density in the biochar-treated mesocosms. Ecosystem CO2 fluxes were unaffected by biochar, but soil Carbon content of biochar-treated mesocosms was significantly lower, signifying a possible movement/loss of biochar or priming effect. Compared to soil texture and crop type, biochar had minimal impact on soil biota, crop production and Carbon Cycling. Future research should examine subtler effects of biochar on biotic regulation of ecosystem production and if the apparent robustness to biochar weakens over greater time spans or in combination with other ecological perturbations.
Philippe Ciais - One of the best experts on this subject based on the ideXlab platform.
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a meta analysis of 1 119 manipulative experiments on terrestrial Carbon Cycling responses to global change
Nature Ecology and Evolution, 2019Co-Authors: Alan K Knapp, Jian Song, Shiqiang Wan, Shilong Piao, Aimee T Classen, Sara Vicca, Philippe CiaisAbstract:Direct quantification of terrestrial biosphere responses to global change is crucial for projections of future climate change in Earth system models. Here, we synthesized ecosystem Carbon-Cycling data from 1,119 experiments performed over the past four decades concerning changes in temperature, precipitation, CO2 and nitrogen across major terrestrial vegetation types of the world. Most experiments manipulated single rather than multiple global change drivers in temperate ecosystems of the USA, Europe and China. The magnitudes of warming and elevated CO2 treatments were consistent with the ranges of future projections, whereas those of precipitation changes and nitrogen inputs often exceeded the projected ranges. Increases in global change drivers consistently accelerated, but decreased precipitation slowed down Carbon-cycle processes. Nonlinear (including synergistic and antagonistic) effects among global change drivers were rare. Belowground Carbon allocation responded negatively to increased precipitation and nitrogen addition and positively to decreased precipitation and elevated CO2. The sensitivities of Carbon variables to multiple global change drivers depended on the background climate and ecosystem condition, suggesting that Earth system models should be evaluated using site-specific conditions for best uses of this large dataset. Together, this synthesis underscores an urgent need to explore the interactions among multiple global change drivers in underrepresented regions such as semi-arid ecosystems, forests in the tropics and subtropics, and Arctic tundra when forecasting future terrestrial Carbon-climate feedback.
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drought and ecosystem Carbon Cycling
Agricultural and Forest Meteorology, 2011Co-Authors: M. K. Van Der Molen, A. J. Dolman, Philippe Ciais, Thomas Eglin, Nadine Gobron, Beverly E. Law, Patrick Meir, Wouter Peters, Oliver L. Phillips, Markus ReichsteinAbstract:Drought as an intermittent disturbance of the water cycle interacts with the Carbon cycle differently than the ‘gradual’ climate change. During drought plants respond physiologically and structurally to prevent excessive water loss according to species-specific water use strategies. This has consequences for Carbon uptake by photosynthesis and release by total ecosystem respiration. After a drought the disturbances in the reservoirs of moisture, organic matter and nutrients in the soil and carbohydrates in plants lead to longer-term effects in plant Carbon Cycling, and potentially mortality. Direct and carry-over effects, mortality and consequently species competition in response to drought are strongly related to the survival strategies of species. Here we review the state of the art of the understanding of the relation between soil moisture drought and the interactions with the Carbon cycle of the terrestrial ecosystems. We argue that plant strategies must be given an adequate role in global vegetation models if the effects of drought on the Carbon cycle are to be described in a way that justifies the interacting processes.
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Drought and ecosystem Carbon Cycling
Agricultural and Forest Meteorology, 2011Co-Authors: M. K. Van Der Molen, A. J. Dolman, Philippe Ciais, Thomas Eglin, Nadine Gobron, Beverly E. Law, Patrick Meir, Wouter Peters, Oliver L. Phillips, Markus ReichsteinAbstract:Drought as an intermittent disturbance of the water cycle interacts with the Carbon cycle differently than the ‘gradual’ climate change. During drought plants respond physiologically and structurally to prevent excessive water loss according to species-specific water use strategies. This has consequences for Carbon uptake by photosynthesis and release by total ecosystem respiration. After a drought the disturbances in the reservoirs of moisture, organic matter and nutrients in the soil and carbohydrates in plants lead to longer-term effects in plant Carbon Cycling, and potentially mortality. Direct and carry-over effects, mortality and consequently species competition in response to drought are strongly related to the survival strategies of species. Here we review the state of the art of the understanding of the relation between soil moisture drought and the interactions with the Carbon cycle of the terrestrial ecosystems. We argue that plant strategies must be given an adequate role in global vegetation models if the effects of drought on the Carbon cycle are to be described in a way that justifies the interacting processes.JRC.DDG.H.3-Global environement monitorin
Markus Reichstein - One of the best experts on this subject based on the ideXlab platform.
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Drought, Heat, and the Carbon Cycle: a Review
Current Climate Change Reports, 2018Co-Authors: Sebastian Sippel, Markus Reichstein, Miguel D. Mahecha, Holger Lange, Milan Flach, Dorothea FrankAbstract:Weather and climate extremes substantially affect global- and regional-scale Carbon (C) Cycling, and thus spatially or temporally extended climatic extreme events jeopardize terrestrial ecosystem Carbon sequestration. We illustrate the relevance of drought and/or heat events (“DHE”) for the Carbon cycle and highlight underlying concepts and complex impact mechanisms. We review recent results, discuss current research needs and emerging research topics. Our review covers topics critical to understanding, attributing and predicting the effects of DHE on the terrestrial Carbon cycle: (1) ecophysiological impact mechanisms and mediating factors, (2) the role of timing, duration and dynamical effects through which DHE impacts on regional-scale Carbon Cycling are either attenuated or enhanced, and (3) large-scale atmospheric conditions under which DHE are likely to unfold and to affect the terrestrial Carbon cycle. Recent research thus shows the need to view these events in a broader spatial and temporal perspective that extends assessments beyond local and concurrent C cycle impacts of DHE. Novel data streams, model (ensemble) simulations, and analyses allow to better understand Carbon cycle impacts not only in response to their proximate drivers (drought, heat, etc.) but also attributing them to underlying changes in drivers and large-scale atmospheric conditions. These attribution-type analyses increasingly address and disentangle various sequences or dynamical interactions of events and their impacts, including compensating or amplifying effects on terrestrial Carbon Cycling.
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drought and ecosystem Carbon Cycling
Agricultural and Forest Meteorology, 2011Co-Authors: M. K. Van Der Molen, A. J. Dolman, Philippe Ciais, Thomas Eglin, Nadine Gobron, Beverly E. Law, Patrick Meir, Wouter Peters, Oliver L. Phillips, Markus ReichsteinAbstract:Drought as an intermittent disturbance of the water cycle interacts with the Carbon cycle differently than the ‘gradual’ climate change. During drought plants respond physiologically and structurally to prevent excessive water loss according to species-specific water use strategies. This has consequences for Carbon uptake by photosynthesis and release by total ecosystem respiration. After a drought the disturbances in the reservoirs of moisture, organic matter and nutrients in the soil and carbohydrates in plants lead to longer-term effects in plant Carbon Cycling, and potentially mortality. Direct and carry-over effects, mortality and consequently species competition in response to drought are strongly related to the survival strategies of species. Here we review the state of the art of the understanding of the relation between soil moisture drought and the interactions with the Carbon cycle of the terrestrial ecosystems. We argue that plant strategies must be given an adequate role in global vegetation models if the effects of drought on the Carbon cycle are to be described in a way that justifies the interacting processes.
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Drought and ecosystem Carbon Cycling
Agricultural and Forest Meteorology, 2011Co-Authors: M. K. Van Der Molen, A. J. Dolman, Philippe Ciais, Thomas Eglin, Nadine Gobron, Beverly E. Law, Patrick Meir, Wouter Peters, Oliver L. Phillips, Markus ReichsteinAbstract:Drought as an intermittent disturbance of the water cycle interacts with the Carbon cycle differently than the ‘gradual’ climate change. During drought plants respond physiologically and structurally to prevent excessive water loss according to species-specific water use strategies. This has consequences for Carbon uptake by photosynthesis and release by total ecosystem respiration. After a drought the disturbances in the reservoirs of moisture, organic matter and nutrients in the soil and carbohydrates in plants lead to longer-term effects in plant Carbon Cycling, and potentially mortality. Direct and carry-over effects, mortality and consequently species competition in response to drought are strongly related to the survival strategies of species. Here we review the state of the art of the understanding of the relation between soil moisture drought and the interactions with the Carbon cycle of the terrestrial ecosystems. We argue that plant strategies must be given an adequate role in global vegetation models if the effects of drought on the Carbon cycle are to be described in a way that justifies the interacting processes.JRC.DDG.H.3-Global environement monitorin
Mary K Firestone - One of the best experts on this subject based on the ideXlab platform.
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metatranscriptomic reconstruction reveals rna viruses with the potential to shape Carbon Cycling in soil
Proceedings of the National Academy of Sciences of the United States of America, 2019Co-Authors: Evan P. Starr, Erin E. Nuccio, Mary K Firestone, Jillian F Banfield, Jennifer PettridgeAbstract:Viruses impact nearly all organisms on Earth, with ripples of influence in agriculture, health, and biogeochemical processes. However, very little is known about RNA viruses in an environmental context, and even less is known about their diversity and ecology in soil, 1 of the most complex microbial systems. Here, we assembled 48 individual metatranscriptomes from 4 habitats within a planted soil sampled over a 22-d time series: Rhizosphere alone, detritosphere alone, rhizosphere with added root detritus, and unamended soil (4 time points and 3 biological replicates). We resolved the RNA viral community, uncovering a high diversity of viral sequences. We also investigated possible host organisms by analyzing metatranscriptome marker genes. Based on viral phylogeny, much of the diversity was Narnaviridae that may parasitize fungi or Leviviridae, which may infect Proteobacteria. Both host and viral communities appear to be highly dynamic, and rapidly diverged depending on experimental conditions. The viral and host communities were structured based on the presence of root litter. Clear temporal dynamics by Leviviridae and their hosts indicated that viruses were replicating. With this time-resolved analysis, we show that RNA viruses are diverse, abundant, and active in soil. When viral infection causes host cell death, it may mobilize cell Carbon in a process that may represent an overlooked component of soil Carbon Cycling.
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Metatranscriptomic reconstruction reveals RNA viruses with the potential to shape Carbon Cycling in soil
bioRxiv, 2019Co-Authors: Evan P. Starr, Erin E. Nuccio, Jennifer Pett-ridge, Jillian F Banfield, Mary K FirestoneAbstract:Abstract Viruses impact nearly all organisms on Earth, with ripples of influence in agriculture, health and biogeochemical processes. However, very little is known about RNA viruses in an environmental context, and even less is known about their diversity and ecology in the most complex microbial system, soil. Here, we assembled 48 individual metatranscriptomes from four habitats within a soil sampled over a 22-day time series: rhizosphere alone, detritosphere alone, a combination of the two, and unamended soil (four time points and three biological replicates per time point). We resolved the RNA viral community, uncovering a high diversity of viral sequences. We also investigated possible host organisms by analyzing metatranscriptome marker gene content. Based on viral phylogeny, much of the diversity was Narnaviridae that parasitize fungi or Leviviridae that infect Proteobacteria. Both host and viral communities appear to be highly dynamic, and rapidly diverged depending on experimental conditions. The viral communities were structured based on the presence of litter, while putative hosts appeared to be impacted by both the presence of litter and roots. A clear time signature from Leviviridae and their hosts indicated that viruses were replicating. With this time-resolved analysis, we show that RNA viruses are diverse, abundant and active in soil. Their replication causes host cell death, mobilizing Carbon in a process that represents a largely overlooked component of Carbon Cycling in soil.