四川卧龙亚高山林线生态交错带群落的种多度关系

Species-abundance relation of herb communities in subalpine timber-line ecotone of Wolong Natural Reserve,Sichuan Province,China

以盖度作为物种多度指标 ,用描述物种多度分布的模型 :断棍分布、几何级数分布、对数级数分布和截尾对数正态分布研究了卧龙巴郎山岷江冷杉林线交错带附近草本群落的种 -多度分布关系。结果表明 ,截尾对数正态分布和对数级数分布能较好地拟合交错带附近群落的种 -多度分布 ,截尾对数正态分布模型更适合交错带群落 ,对数级数分布较好地适合亚高山草甸群落。对数级数分布的参数 α和对数正态分布的参数 λ是反映群落结构特征内在性质的量 ,可以作为物种多样性指数运用 ,它们能较好地反映群落的物种丰富度。上述两个参数值的变化趋势表明 ,由岷江冷杉林到林线交错带 ,物种多样性逐渐增加 ,并在林线交错带出现峰值 ;经林线向林外草甸多样性逐渐降低 ,但亚高山草甸仍比岷江冷杉林内草本群落拥有更高的物种多样性。

By using species abundance distribution models Broken Stick,Geometric Serices,Log Series and Truncated Log Normal,percent cover of every species was used as indicator of abundance to study species abundance relations of herb communities along transects across subalpine timberline ecotone of Abies faxoniana forest in Balang Mountain of Wolong Natural Reserve,Sichuan Province,southwestern China.The results showed that Truncated Log Normal and Log Series distribution models can well fit to the species abundance distribution of communities nearby timberline ecotone.The parameters of Log Series distribution α and of Truncated Log Normal λ ,the intrinsic characteristics related to community structure,may be used as species diversity indices.They corresponded with species richness of communities fairly well.These parameters increasingly went up to maximum from fir forest to timberline ecotone,then decreased gradually through forest boundary to subalpine meadow.However,subalpine meadow possessed higher species diversity than herb communities within fir forest.