title: Divergent changes in plant community composition under 3-decade grazing exclusion in continental steppe.
abstract: An understanding of the factors controlling plant community composition will allow improved prediction of the responses of plant communities to natural and anthropogenic environmental change. Using monitoring data from 1980 to 2009, we quantified the changes in community composition in Leymus chinensis and Stipa grandis dominated grasslands in Inner Mongolia under long-term grazing-exclusion and free-grazing conditions, respectively. We demonstrated that the practice of long-term grazing exclusion has significant effects on the heterogeneity, the dominant species, and the community composition in the two grasslands. The community composition of L. chinensis and S. grandis grasslands exhibited directional changes with time under long-term grazing exclusion. Under free grazing, the L. chinensis community changed directionally with time, but the pattern of change was stochastic in the S. grandis community. We attributed the divergent responses to long-term grazing exclusion in the S. grandis and L. chinensis grasslands to litter accumulation and changes in the microenvironment after grazing exclusion, which collectively altered the growth and regeneration of the dominant species. The changes in the grazed grasslands were primarily determined by the selective feeding of sheep during long-term heavy grazing. Overall, the responses of the community composition of the Inner Mongolian grasslands to long-term grazing exclusion and heavy grazing were divergent, and depended primarily on the grassland type. Our findings provide new insights into the role of grazing in the maintenance of community structure and function and therefore have important implications for grassland management.
authors.affiliation: Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China. henp@igsnrr.ac.cn
authors.forename: Nianpeng
authors.initials: N
authors.lastname: He
authors.forename: Xingguo
authors.initials: X
authors.lastname: Han
authors.forename: Guirui
authors.initials: G
authors.lastname: Yu
authors.forename: Quansheng
authors.initials: Q
authors.lastname: Chen
mesh_terms: D044822:Biodiversity; D010944:Plants / Q000145:classification*
references.citation: Ecology. 2008 Jan;89(1):216-25
references.pmid: 18376563
references.citation: Ecology. 2006 Nov;87(11):2746-54
references.pmid: 17168019
references.citation: Ecol Lett. 2005 Nov;8(11):1175-82
references.pmid: 21352441
references.citation: Oecologia. 1990 Nov;85(1):8-13
references.pmid: 28310949
references.citation: Nature. 2004 Sep 9;431(7005):181-4
references.pmid: 15356630
references.citation: Am Nat. 2000 Mar;155(3):311-325
references.pmid: 10718728
references.citation: J Environ Qual. 2008 Mar-Apr;37(2):663-8
references.pmid: 18396553
references.citation: Oecologia. 2010 Mar;162(3):771-80
references.pmid: 19921269
references.citation: PLoS One. 2010 Jan 06;5(1):e8562
references.pmid: 20066035
references.citation: Ecology. 2006 Aug;87(8):2058-67
references.pmid: 16937645