Abstract
Plant diversity strongly influences ecosystem functions and services, such as soil carbon storage. However, the mechanisms underlying the positive plant diversity effects on soil carbon storage are poorly understood. We explored this relationship using long-term data from a grassland biodiversity experiment (The Jena Experiment) and radiocarbon ((14)C) modelling. Here we show that higher plant diversity increases rhizosphere carbon inputs into the microbial community resulting in both increased microbial activity and carbon storage. Increases in soil carbon were related to the enhanced accumulation of recently fixed carbon in high-diversity plots, while plant diversity had less pronounced effects on the decomposition rate of existing carbon. The present study shows that elevated carbon storage at high plant diversity is a direct function of the soil microbial community, indicating that the increase in carbon storage is mainly limited by the integration of new carbon into soil and less by the decomposition of existing soil carbon.
Highlights
Plant diversity strongly influences ecosystem functions and services, such as soil carbon storage
Traditional explanatory theories focus on the recalcitrance of less-reactive compounds and physical protection as controls of soil carbon stocks, while more recent theories highlight the importance of soil microorganisms for the persistence of soil organic matter
Carbon uptake in rhizospheric microorganisms at high plant diversity was increased compared with low plant diversity (Fig. 5) as indicated by a complementary 13CO2 labelling experiment in the Ecotron facility in Montpellier (Methods)
Summary
Effects of plant diversity on soil organic carbon changes. In 2011, 9 years after the establishment of The Jena Experiment, soil carbon concentration in the topsoil layer Impact of plant diversity (plant species richness (PSR, log transformed) and number of plant functional groups (FGs)) and the presence of distinct plant functional groups (legumes, grasses, small herbs, tall herbs) on changes in soil organic carbon (DCorg 0–5 and 0–30 cm), genetic diversity (determined using terminal-restriction fragment length polymorphism (TRFLP)) of the soil microbial community (fungi and bacteria) and changes in d15N (D15N 0–5 cm). Numbers provide F-values, asterisks denote their significance: *, o0.05; **, o0.01; or ***, o0.001. Detailed analysis of variance (ANOVA) results are given in Supplementary Table 1
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