Nitrogen deposition weakens plant–microbe interactions in grassland ecosystems |
| |
Authors: | Cunzheng Wei Qiang Yu Edith Bai Xiaotao Lü Qi Li Jianyang Xia Paul Kardol Wenju Liang Zhengwen Wang Xingguo Han |
| |
Institution: | 1. State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, , Beijing, 100093 China;2. University of Chinese Academy of Sciences, , Beijing, 100049 China;3. State Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences, , Shenyang, 110164 China;4. Department of Biology, Graduate Degree Program in Ecology, Colorado State University, , Fort Collins, Colorado, 80523 USA;5. Department of Botany and Microbiology, University of Oklahoma, , Norman, OK, USA;6. Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, , Ume?, 901 83 Sweden |
| |
Abstract: | Soil carbon (C) and nitrogen (N) stoichiometry is a main driver of ecosystem functioning. Global N enrichment has greatly changed soil C : N ratios, but how altered resource stoichiometry influences the complexity of direct and indirect interactions among plants, soils, and microbial communities has rarely been explored. Here, we investigated the responses of the plant‐soil‐microbe system to multi‐level N additions and the role of dissolved organic carbon (DOC) and inorganic N stoichiometry in regulating microbial biomass in semiarid grassland in northern China. We documented a significant positive correlation between DOC and inorganic N across the N addition gradient, which contradicts the negative nonlinear correlation between nitrate accrual and DOC availability commonly observed in natural ecosystems. Using hierarchical structural equation modeling, we found that soil acidification resulting from N addition, rather than changes in the plant community, was most closely related to shifts in soil microbial community composition and decline of microbial respiration. These findings indicate a down‐regulating effect of high N availability on plant–microbe interactions. That is, with the limiting factor for microbial biomass shifting from resource stoichiometry to soil acidity, N enrichment weakens the bottom‐up control of soil microorganisms by plant‐derived C sources. These results highlight the importance of integratively studying the plant‐soil‐microbe system in improving our understanding of ecosystem functioning under conditions of global N enrichment. |
| |
Keywords: | aboveground‐belowground linkages compensatory effects microbial carbon limitation N saturation resource stoichiometry structural equation modeling |
|
|