Two key features influencing community assembly processes at regional scale: Initial state and degree of change in environmental conditions. Issue 24 (25th November 2018)

• Record Type: Journal Article
• Authors: Feng, Youzhi; Chen, Ruirui; Stegen, James C.; Guo, Zhiying; Zhang, Jianwei; Li, Zhongpei; Lin, Xiangui
• Is Part Of: Molecular ecology. Volume 27:Issue 24(2018)
• Page Start: 5238
• Page End: 5251
• Publication Date: 2018-11-25
• Subjects: community assembly -- deterministic -- microbial ecology -- null models -- soil bacterial community -- soil organic matter -- stochastic; Molecular ecology -- Periodicals; Molecular population biology -- Periodicals; 576
• DOI: 10.1111/mec.14914
• Languages: English
• ISSNs: 0962-1083

Abstract

Abstract: Belowground microbial communities strongly influence ecosystem function such that predicting function may rely on understanding ecological processes that assemble communities. Uncertainty remains, however, in what governs the relative contributions of different ecological processes. To help fill this knowledge gap, we test the general hypothesis that both initial state and degree of change in environmental conditions govern the relative contributions of different ecological assembly processes. To do so, we leveraged regional‐scale nutrient and organic matter addition experiments and used soil organic matter (SOM) as a proxy of integrated soil environmental conditions. Consistent with our hypothesis, we found that both the initial amount of SOM and the degree of change in SOM—in response to nutrient addition—influenced the relative contributions of different ecological assembly processes. These influences were most clearly observed at the regional scale, suggesting potential scale dependence. More specifically, nutrient additions homogenized bacterial community composition due to enhanced influences of homogenizing dispersal when SOM content was initially high. In contrast, nutrient additions led to divergence in community composition due to variable selection when initial SOM was low and/or when SOM increased significantly in response to nutrient additions. Our findings indicate important connections among initial conditions, degree of change in environmental variables and microbial community assembly processes that may influence ecosystem processes. These conceptual inferences highlight a need to strengthen connections between ecological theory and biogeochemical modelling.