基于西双版纳20 hm2森林动态监测样地内直径≥1 cm的树种资料,分析该样地树种多度(个体数)和丰富度(物种数)及其方差与变异系数在7个取样尺度(5m×5m,10mx 10m,20m×20m,25m×25m,50m×50m,100 m×100m,200 m×250 m)的变化规律.结果显示:(1)西双版纳热带雨林样地环境异质性较大,多度和丰富度随着尺度的增加均表现非线性增加.(2)多度的方差随尺度增加而线性增加；丰富度的方差与尺度都表现出非线性的关系.丰富度的方差在尺度100m×100m上最大.(3)多度、丰富度和多样性指数的方差、变异系数均大于随机分布模型拟合的数值,表明树种在样地内分布不是随机分布.总之,在生物多样性的保护和管理中要特别注意,尽管多度具有可加性,只有当环境异质性不大时用小尺度多度估计大尺度多度才比较可靠;丰富度的非线性变化使得一个尺度上生物多样性“热点”,在另一个取样尺度上却可能为“冷点”.%Based on trees with DBH ≥ 1 cm in a 20 hm2 stem-mapped tropical forest of Xishuangbanna, this study investigated spatial variation of abundance and richness across seven scales (grain sizes) (5 m×5 m, 10 m×10 m, 20 m × 20 m, 25 m× 25 m, 50 m× 50 m, 100 m× 100 m, 200 m× 250 m). The results show ed that (1) abundance and richness did not have a linear relation with scale due to the heterogeneity of the Xishuangbanna tropical rainforest plot. (2) The spatial variances of richness typically had a nonlinear relationship with scale, but abundance is linearly dependent on scale. The spatial variance of richness has a hat shape across scale with the largest variance occurring at 100 m×100 m. (3) The variances of abundance and richness werelarger than those of the random placement model, reflecting that spatial distribution of species in the study area was more correspondent to habitat heterogeneity than random distribution. For the purposes of diversity management and conservation, only when habitat is homogeneous, abundance in large scale could be estimated from extrapolation. In addition, the non-additive property of richness made the identification of biodiversity hotspots problematic as a hotspot at one scale could become a coldspot at another scale.
展开▼
