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放牧梯度上群落物种数与物种组成结构异质性的数量分析 预览 被引量:3

Quantitative analysis of spatial heterogeneity in species richness and composition in grassland vegetation with different grazing intensities in the northeast Inner Mongolian steppe
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摘要 放牧干扰对草原的植物物种组成以及群落结构的影响过程是群落生态学的重要内容。在内蒙古呼伦贝尔草原轻牧、中牧、重牧3个样地上,设置100个0.25 m2的小样方,通过调查种类组成,比较小尺度区分面积上的物种多样性及物种数目的空间分异性;采用Bray-Curtis相似性指数法研究了不同放牧梯度上物种组成结构异质性的变化趋势。结果表明:样地群落物种数表现为轻牧>中牧>重牧,而小尺度样方内物种数与物种多样性均呈现中牧>轻牧>重牧趋势;在轻牧条件下,整体来看,小样方内物种数目的分布围绕平均值具有较小波动;在重度放牧区,不存在维持多个物种数的样方;而在中度放牧区,物种数的空间分布呈现"凹型"格局,相比于轻牧、重牧阶段,物种数在样方中的平均分布程度降低,即物种数目很多或很少的样方大量存在。从物种结构的空间异质性来看,轻牧区样方之间种类组成的相似性不明显,群落物种形成均匀分布;中度和重度放牧区,具有随机分布的群落物种结构。牧压影响小尺度区间面积上的物种数、种类构成及其空间异质性,物种数目的频度分布及种类成分相似性的蒙特卡罗模似统计运算,能够较好地拟合不同放牧梯度上物种分布的空间格局,反映群落演替动态。 Spatial heterogeneity is a very important structural property in ecosystem and is closely associated with many ecological phenomena.Heterogeneity is defined as 'the complexity and/or variability of a system property in space and/or time'-could be an important component controlling plant community structure and composition.The spatial distribution of biological and abiotic factors in ecosystem has the features of spatial heterogeneity.Although the effects of grazing on the vegetation patches in arid and semiarid ecosystems have been extensively described,knowledge of these ecological processes in China is rather poor,particularly in Inner Mongolian,northern China.In this paper,the spatial heterogeneity of vegetation under different grazing intensities was examined using geostatistical methods.The effect of grazing disturbance on plant functional group and community structure of grass community is an important component of community ecology.In the present study,we arranged 100 quadrats of 50 cm × 50 cm in three grassland sites with different grazing intensities(light,medium,and heavy) in the northeast Inner Mongolian steppe.There are 4 cells of 25 cm×25 cm in each quadrats.Through investigation of grass species,the spatial heterogeneities of small-scale species richness and small-scale species compositions were compared and studied.The Bray-Curtis was used to express the spatial heterogeneity of species composition with different grazing intensities.Results show that: The order of species richness for the entire area was light grazing > moderate grazing > heavy grazing.However,the order of species richness for small quadrat was medium grazing > light grazing > heavy grazing.Over all,the number of species occurring in each quadrat did not deviate substantially from the mean;in the heavily grazed site,quadrats with numerous species did not exist;in the medium grazing site,the distribution of spatial richness showed the 'concave' pattern and the average distribution of species richness reduced(i.e.quadrats with nume
作者 乌云娜 张凤杰 盐见正卫 Wuyunna1,ZHANG Feng-jie1,Shiyomi Masae2 (1 College of Environment and Resources,Dalian Nationalities University,Dalian 116600,Liaoning,China; 2 Ibaraki University,Professor Emeritus,Mito 310-8512,Japan)
出处 《干旱区地理》 CSCD 北大核心 2011年第6期 904-911,共8页 Arid Land Geography
基金 国家自然科学基金项目(30870423,31170402) 国家973项目(2009CB421308) 中央高校基本科研业务费专项(DC10050101)共同资助
关键词 物种数目 物种结构 空间异质性 草原群落 放牧梯度 species number species composition spatial heterogeneity grassland communities grazing gradient
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