放牧
问题10
非生物成分
自养
草原
异养
土壤呼吸
呼吸
草原
氮气
农学
动物科学
化学
环境科学
生物
生态学
植物
细菌
有机化学
遗传学
作者
Baoku Shi,Fu Xiao,Melinda D. Smith,Anping Chen,Alan K. Knapp,YangQuan Chen,Wanling Xu,Rui Zhang,Weifeng Gao,Wei Sun
出处
期刊:Catena
[Elsevier]
日期:2022-06-01
卷期号:213: 106207-106207
被引量:3
标识
DOI:10.1016/j.catena.2022.106207
摘要
A quantitative understanding of temporal patterns of soil respiration (SR) and its components, as well as of their controlling factors, are key to the estimation of grassland C sequestration under different scenarios of land-use change and global change. However, the sensitivity of seasonal patterns and magnitude of SR and its components to N addition (N) and grazing (G) and their interactions remains poorly understood. We carried out an experiment with N, G and N addition plus grazing (NG) treatments in temperate meadow steppe located in the easternmost of the Eurasian steppe. We measured SR and its components, i.e., autotrophic respiration (AR) and heterotrophic respiration (HR), along with a suite of other biotic and abiotic factors over 3 years. N addition increased AR when compared to the control treatment (CK), whereas moderate grazing decreased AR, and N addition and grazing had additive effects on AR. We found that aboveground biomass was the predominant controlling factor of AR. However, the N, G and NG treatments had no significant effects on HR. Although N addition and grazing caused changes in a series of biotic and abiotic factors (e.g. total PLFAs, soil fungal/bacterial ratio and bulk density) that controlled soil microbial metabolic processes, collectively these effects on HR appeared to offset each other. Moreover, compared to the CK and N treatments, G and NG treatments reduced the apparent temperature sensitivity (Q10) of AR and HR. Grazing dampened the positive response of Q10 of HR to N addition. Our study suggests that AR and HR are regulated by different underlying mechanisms and respond differently to N and G, and therefore should be modeled separately to improve models and predictions of ecosystem C cycling. Our study also indicates that moderate grazing could produce beneficial effects on meadow steppe carbon sequestration under future scenarios of nitrogen deposition and climate warming.
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