Pedosphere (6): 905--915, 2023
ISSN 1002-0160/CN 32-1315/P
©2023 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Soil microbial respiration is regulated by stoichiometric imbalances: Evidence from a humidity gradient case |
Jiwei LI1,2,5,6, Jiangbo XIE3, Jianzhao WU1, Yongxing CUI4, Lingbo DONG1, Yulin LIU2,5, Xuying HAI1, Yan LI3, Zhouping SHANGGUAN1,2, Kaibo WANG6, Changhui PENG7, Lei DENG1,2 |
1 State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, College of Soil and Water Conservation Science and Engineering(Institute of Soil and Water Conservation), Northwest A&F University, Yangling 712100(China);
2 Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling 712100(China);
3 State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Lin'an 311300(China);
4 Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University, Beijing 100871(China);
5 University of Chinese Academy of Sciences, Beijing 100049(China);
6 State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061(China);
7 Center of CEF/ESCER, Department of Biological Science, University of Quebec at Montreal, Montreal H3C 3P8(Canada) |
| ABSTRACT |
| Humidity not only affects soil microbial respiration (SMR) directly, but, indirectly by regulating the availability of soil water and nutrients. However, the patterns of direct and indirect effects of humidity on SMR over large precipitation gradients remain unclear, limiting our understanding of the effects of precipitation changes on soil C cycle. Here, we investigated the relationships among humidity, soil nutrients, and SMR by identifying stoichiometric imbalances, microbial elemental homeostasis, and microbial C use efficiency along a precipitation gradient at a continental scale. The relationship between SMR and humidity index (HI) corresponded to a Richard’s curve with an inflection point threshold value of approximately 0.7. Soil microbial respiration increased with increasing humidity in drier areas (HI < 0.7), but tended to balance above this threshold. Increasing humidity exacerbated C:P and N:P imbalances across the selected gradient. Severe N and P limitations in soil microbial communities were observed in drier areas, while soil microbes suffered from aggravated P limitation as the humidity increased in wetter areas (HI > 0.7). Soil microbial communities regulated their enzyme production to maintain a strong stoichiometric homeostasis in drier areas; enzyme production, microbial biomass, and threshold elemental ratios were non-homeostatic under P limitation in wetter areas, which further contributed to the increase in SMR. Our results identified a moisture constraint on SMR in drier areas and highlighted the importance of nutrient (especially for P) limitations induced by humidity in regulating SMR in wetter areas. Understanding the modulation of SMR via soil enzyme activity may improve the prediction of soil C budget under future global climate change. |
| Key Words: carbon use efficiency,ecological stoichiometry,microorganisms,nutrient limitations,precipitation,soil enzyme activities,stoichiometric homeostasis |
| Citation: Li J W, Xie J B, Wu J Z, Cui Y X, Dong L B, Liu Y L, Hai X Y, Li Y, Shangguan Z P, Wang K B, Peng C H, Deng L. 2023. Soil microbial respiration is regulated by stoichiometric imbalances: Evidence from a humidity gradient case. Pedosphere. 33(6): 905-915. |
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