Dataset Information

Microbial Diversity Indexes Can Explain Soil Carbon Dynamics as a Function of Carbon Source.

ABSTRACT: Mathematical models do not explicitly represent the influence of soil microbial diversity on soil organic carbon (SOC) dynamics despite recent evidence of relationships between them. The objective of the present study was to statistically investigate relationships between bacterial and fungal diversity indexes (richness, evenness, Shannon index, inverse Simpson index) and decomposition of different pools of soil organic carbon by measuring dynamics of CO2 emissions under controlled conditions. To this end, 20 soils from two different land uses (cropland and grassland) were incubated with or without incorporation of 13C-labelled wheat-straw residue. 13C-labelling allowed us to study residue mineralisation, basal respiration and the priming effect independently. An innovative data-mining approach was applied, based on generalized additive models and a predictive criterion. Results showed that microbial diversity indexes can be good covariates to integrate in SOC dynamics models, depending on the C source and the processes considered (native soil organic carbon vs. fresh wheat residue). Specifically, microbial diversity indexes were good candidates to help explain mineralisation of native soil organic carbon, while priming effect processes seemed to be explained much more by microbial composition, and no microbial diversity indexes were found associated with residue mineralisation. Investigation of relationships between diversity and mineralisation showed that higher diversity, as measured by the microbial diversity indexes, seemed to be related to decreased CO2 emissions in the control soil. We suggest that this relationship can be explained by an increase in carbon yield assimilation as microbial diversity increases. Thus, the parameter for carbon yield assimilation in mathematical models could be calculated as a function of microbial diversity indexes. Nonetheless, given limitations of the methods used, these observations should be considered with caution and confirmed with more experimental studies. Overall, along with other studies on relationships between microbial community composition and SOM dynamics, this study suggests that overall measures of microbial diversity may constitute relevant ways to include microbial diversity in models of SOM dynamics.

SUBMITTER: Louis BP

PROVIDER: S-EPMC4995005 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Microbial Diversity Indexes Can Explain Soil Carbon Dynamics as a Function of Carbon Source.

Louis Benjamin P BP Maron Pierre-Alain PA Menasseri-Aubry Safya S Sarr Amadou A Lévêque Jean J Mathieu Olivier O Jolivet Claudy C Leterme Philippe P Viaud Valérie V

PloS one 20160823 8

Mathematical models do not explicitly represent the influence of soil microbial diversity on soil organic carbon (SOC) dynamics despite recent evidence of relationships between them. The objective of the present study was to statistically investigate relationships between bacterial and fungal diversity indexes (richness, evenness, Shannon index, inverse Simpson index) and decomposition of different pools of soil organic carbon by measuring dynamics of CO2 emissions under controlled conditions. T ...[more]

PMID: 27551779

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Project description:Returning crop residues is a possible practice for balancing soil carbon (C) loss. The turnover rate of organic C from crop residues to soil C is dependent on soil microbial community dynamics. However, the relationship between any temporal changes in the soil microbial community after crop straw inputs and the dynamics of straw-C distribution in the soil organic carbon (SOC) pool remains unclear. The present study investigated the allocation of straw-C into soil dissolved organic carbon (DOC), microbial biomass carbon (MBC), particulate organic carbon (POC) and mineral-associated organic carbon (MaOC) using stable isotope probing, as well as the temporal changes in the soil bacterial and fungal communities using high-throughput sequencing. After the first 180 days of straw decomposition, approximately 3.93% and 19.82% of straw-C was transformed into soil MaOC and POC, respectively, while 0.02% and 2.25% of straw-C was transformed into soil DOC and MBC, respectively. The temporal change of the soil microbial community was positively correlated with the dynamics of straw-C distribution to SOC (R > 0.5, P < 0.05). The copiotrophic bacteria (e.g., Streptomyces, Massilia and Sphingobacterium), cellulolytic bacteria and fungi (e.g., Dyella and Fusarium, Talaromyces), acidophilic bacteria (e.g., Edaphobacter and unclassified Acidobacteriaceae), denitrifying and N-fixing microbes (e.g., Burkholderia-Paraburkholderia, Paraphaeosphaeria and Bradyrhizobium), and fungi unclassified Sordariomycetes were significantly correlated with straw-C distribution to specific SOC fractions (P < 0.05), which explained more than 90% of the variation of straw-C allocation into soils. Copiotrophic, certain cellulolytic and denitrifying microbes had positively correlated with DOC- and MaOC-derived from straw, and other cellulolytic fungi (e.g., Talaromyces) and specific bacteria (e.g. Bradyrhizobium) were positively correlated with POC-derived from straw. Our results highlight that the temporal change of soil microbial community structure well reflects the conversion and distribution process of straw-C to SOC fractions.

Project description:The enrichment of H2-oxidizing bacteria (HOB) by H2 generated by nitrogen-fixing nodules has been shown to have a fertilization effect on several different crops. The benefit of HOB is attributed to their production of plant growth-promoting factors, yet their interactions with other members of soil microbial communities have received little attention. Here we report that the energy potential of H2, when supplied to soil, alters ecological niche partitioning of bacteria and fungi, with multifaceted consequences for both generalist and specialist microbial functions. We used dynamic microcosms to expose soil to the typical atmospheric H2 mixing ratio (0.5 ppmv) permeating soils, as well as mixing ratios comparable to those found at the soil-nodule interface (10,000 ppmv). Elevated H2 exposure exerted direct effects on two HOB subpopulations distinguished by their affinity for H2 while enhancing community level carbon substrate utilization potential and lowering CH4 uptake activity in soil. We found that H2 triggered changes in the abundance of microorganisms that were reproducible yet inconsistent across soils at the taxonomic level and even among HOB. Overall, H2 exposure altered microbial process rates at an intensity that depends upon soil abiotic and biotic features. We argue that further examination of direct and indirect effects of H2 on soil microbial communities will lead to a better understanding of the H2 fertilization effect and soil biogeochemical processes.IMPORTANCE An innovative dynamic microcosm chamber system was used to demonstrate that H2 diffusing in soil triggers changes in the distribution of HOB and non-HOB. Although the response was uneven at the taxonomic level, an unexpected coordinated response of microbial functions was observed, including abatement of CH4 oxidation activity and stimulation of carbon turnover. Our work suggests that elevated H2 rewires soil biogeochemical structure through a combination of direct effects on the growth and persistence of HOB and indirect effects on a variety of microbial processes involving HOB and non-HOB.

Dataset Information

Microbial Diversity Indexes Can Explain Soil Carbon Dynamics as a Function of Carbon Source.

Publications

Microbial Diversity Indexes Can Explain Soil Carbon Dynamics as a Function of Carbon Source.

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