木林子天然次生林典型群落物种多度分布格局的尺度效应

Responses of Species-abundance Distribution to Varying Sampling Scales in a Typical Forest Community in Mulinzi Nature Reserve

物种多度分布格局作为研究群落结构的基本格局,是理解群落性质的重要基础.为分析物种多度格局对取样面积的响应,探讨多度格局的形成机制,本研究以木林子国家级自然保护区典型群落——川陕鹅耳枥+青冈-水马桑(Carpinus fargesiana+Cyclobalanopsis glauca-Weigela japonica)群落15个20 m×20 m森林动态监测样地为背景,采用累积经验分布函数描述6个取样尺度(10 m×10 m,20 m×20 m,30 m×30 m,40 m×40 m,50 m×50 m,60 m×60 m)物种多度分布的空间变异性,进而用断棍模型拟合物种多度分布曲线,并基于χ2检验和AIC值检验模型拟合效果.结果表明:(1)6个尺度下物种的多度分布较为均匀,且群落中稀有种和常见种的比例相对稳定.(2)断棍模型在各个尺度下均可以被接受,且在越小的尺度上拟合效果越好.(3)生态位理论在小尺度上能较好的解释断棍模型与实际物种多度分布格局的差异.

Species abundance distribution （SAD） is an important pattern to understand the structure and character of community.We analyzed the responses of SAD to varying sampling scales and formation mechanism of SAD.We used data collected in 2014 from fifteen 20 m×20 m dynamic plot in a typical forest community （Carpinus fargesiana＋Cyclobalanopsis glauca-Weigela japonica） in the Mulinzi Nature Reserve.Empirical cumulative distribution function （ECDF） was selected to describe the spatial variation of SAD at six different scales.We subsequently used broken stick model （BSM） to fit the SAD,used χ ^2 and AIC values to test goodness-of-fit.The results showed：①SADs were uniform,and the ratio of rare and common species was nearly at six scales.②BSM was accepted in six scales,and the goodness-of-fit was better at smaller scales.③Ecological niche could explain the differences between BSM and observed SADs.