放牧强度和地形对内蒙古典型草原物种多度分布的影响  

Effects of grazing intensity and topography on species abundance distribution in a typical steppe of Inner Mongolia

作　　者：李文怀[1,2] 郑淑霞[1,3] 白永飞[1] 

机构地区：[1]中国科学院植物研究所植被与环境变化国家重点实验室,北京100093 [2]中国科学院大学生命科学学院,北京100049 [3]中国科学院水利部水土保持研究所黄土高原土壤侵蚀与旱地农业国家重点实验室,陕西杨凌712100

出　　处：《植物生态学报》2014年第2期178-187,共10页Chinese Journal of Plant Ecology

基　　金："十二五"农村领域国家科技计划项目(2012BAD16B03);国家科技支撑计划项目(2011-BAC07B01);中国科学院战略性先导科技专项(XDA05050400)

摘　　要：为了更好地理解放牧对草原生态系统物种多度分布格局的影响,以及常见种和稀有种对维持群落多样性的作用,以内蒙古典型草原为研究对象,基于长期放牧控制实验平台(包括7个载畜率水平(0、1.5、3.0、4.5、6.0、7.5、9.0 sheep·hm–2)和两种地形系统(平地和坡地)),研究了群落内全部物种、常见种和稀有种的丰富度和多度对放牧强度的响应规律,并选取对数正态模型、对数级数模型和幂分割模型,对物种多度数据进行拟合。结果表明:1)平地系统中,物种丰富度和多度在低放牧强度下(1.5、3.0 sheep·hm–2)增加,而在中、高度放牧强度下(4.5–9.0 sheep·hm–2)降低,全部物种的多度分布在大多数放牧强度下符合幂分割模型,在高放牧强度下也符合对数正态模型;坡地系统中,物种丰富度和多度随着放牧强度增加而显著降低,全部物种的多度分布在各个放牧强度下,均符合幂分割模型和对数正态模型。2)随着放牧强度增加,常见种的多度响应趋势与全部物种的响应趋势一致,其多度分布均符合幂分割模型和对数正态模型;稀有种的丰富度响应趋势与全部物种的响应趋势一致,其多度分布符合幂分割模型,同时也部分符合对数正态和对数级数模型。总之,适宜的载畜率有利于生物多样性和初级生产力的提高,平地系统中物种多度的响应在一定程度上支持放牧优化假说;而坡地系统中不同物种多度的响应差异说明:确定最佳载畜率时,还需要考虑地形因素的影响。此外,模型的拟合结果表明:生态位分化机制对内蒙古典型草原物种多度分布起着主要作用,常见种和稀有种通过不同的响应方式共同维持着草原生态系统的物种多样性。Aims Our objective is to determine： 1） how species richness and abundance vary with grazing intensity and topography （i.e., flat vs. slope） in typical steppe of Inner Mongolia grassland, and 2） how common and rare species respond to grazing intensity and what role they play in species diversity maintenance. Methods The study was carried out at the Sino-German grazing experiment site, which was established in June 2004, and located in the typical steppe region of Inner Mongolia grassland dominated by Leymus chinensis and Stipa grandis. The experimental treatments included seven levels of stocking rates （i.e., 0, 1.5, 3.0, 4.5, 6.0, 7.5, 9.0 sheep.hm-2） and two topographical systems （i.e., fiat and slope）. Three hundred quadrats （1 m x 1 m each） were investigated on each plot in August 2009, and the total number of species and the number of individuals for each species were measured within each quadrat. The log-normal model, log-series model, and power fraction model were used to fit the observational data. Important findings Our results showed that the species richness and abundance increased at low stocking rates （1.5, 3.0 sheep.hm-2）, but decreased at high stocking rates （7.5, 9.0 sheep.hm-2） on the flat, which partially sup- ported the grazing optimization hypothesis. The power fraction model well fitted for entire species abundance at most of stocking rates, while the log-normal model only fitted well for entire species abundance just at the high stocking rates. The species richness and abundance decreased greatly with stocking rates on slopes. Abundancedistribution of entire species at each of the stocking rates followed the log-normal function and power fraction function. The groups of common species and the entire species had similar responses in abundance to grazing at each of the stocking rates on both the flat and the slope, which were well fitted by both the power fraction model and log-normal model; whereas the groups of rare species and the entire species had similar rich

关 键 词：多度分布 常见种 放牧强度 稀有种 物种丰富度 典型草原 

分 类 号：S812[农业科学—草业科学]