Abstract
To predict the consequences of environmental change on the structure and composition of communities, it is necessary to also understand the regional drivers underlying the structuring of these communities. Here, we have taken a hypothesis-based approach to test the relative importance of niche versus neutral processes using niche overlap, species traits and population asynchrony in two crossed treatments of fertilization and grazing in an alpine meadow community. Our results suggested that the observed species biomass overlap was not significantly different between treatments of grazing, grazing × fertilization and grazer exclusion. In contrast, the species biomass overlap was higher than expected in fertilization treatments when grazers were excluded. On the one hand, we found no relationship between species traits and relative abundance in grazing, grazing × fertilization and grazer-exclusion treatments; on the other hand, mechanistic trait-based theory could be used to predict species relative abundance patterns in fertilization treatments when grazers were excluded. From grazing to fertilization, when grazers were excluded, there was a slight increase in species synchrony, which indicated that the complementary dynamic of species gradually changed from complete independence into synchronously fluctuating with increasing fertilization. Based on the above results, we concluded that stochastic and deterministic processes formed ends of a continuum from grazing to fertilization when grazers were excluded in an alpine meadow plant community, and the importance of niche differences between species in structuring grassland communities increased with increasing fertilization and decreased with grazing.
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Acknowledgments
We thank Dr. Jacob Weiner and Charlotte Chang for helpful discussions and comments on the manuscript; Dr. Peng Jia for assistance with the data analysis; Dr. Shujun Wen, Dr. Xin Chen, Dr. Wei Li, Dr. Chunhui Zhang, Dr. Xiaoming Shi, Yuanzhen Zhu, Liujie Wang, Xiao Yang, Wenxiang Hu, and many others at the Maqu Rangeland Workgroup for assistance in both the field and lab. This project was supported by the Key Program of the National Natural Science Foundation of China (grant no:40930533). These experiments comply with current laws of China.
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Communicated by Melinda Smith.
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Yang, Z., Guo, H., Zhang, J. et al. Stochastic and deterministic processes together determine alpine meadow plant community composition on the Tibetan Plateau. Oecologia 171, 495–504 (2013). https://doi.org/10.1007/s00442-012-2433-6
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DOI: https://doi.org/10.1007/s00442-012-2433-6