黄土高原马栏林区基于不同植被组织尺度的群落物种多样性

Species diversity of communities based on different vegetation organizational scales in China’s Malan forest region

物种多样性格局随着时空尺度的变化而变化,同时也与植被组织尺度的变化密切相关,基于多组织尺度的研究能更好地揭示一个地区的物种多样性规律。在应用数量分类(TWINSPAN)和主成分分析法(PCA)确定黄土高原马栏林区不同组织尺度的群落类型及其相互关系的基础上,采用加性分配法分析该区域物种多样性与植被型、群系和群丛3种植被组织尺度之间的关系,结果表明:(1)区域物种多样性(γ)可加性分配分为群丛内(α1)、群丛间(β1)、群系间(β2)和植被型间(β3)4个多样性成分,无论用物种丰富度指数还是Shannon-Wiener多样性或Simpson多样性指数,乔木、灌木和草本植物的最大物种多样性都存在于群丛内(草本层的物种丰富度除外),说明群丛尺度是度量该区物种多样性的最佳尺度。(2)植被型、群系和群丛3种组织尺度的Shannon-Wiener多样性百分比均大于Simpson多样性百分比,说明稀有种的分布对马栏林区各植被组织尺度的物种多样性格局起主要作用。(3)各尺度间的β多样性大小顺序在乔木、灌木、草本植物3层以不同多样性指数表示时各不相同,这与乔木、灌木、草本植物3层的物种组成和分布,以及主导不同植被组织尺度的物种多样性的因素差异有密切联系。

Aims Patterns of species diversity are closely related to vegetation organizational scales. Our aims were to analyze the relationship between species diversity and vegetation organizational scales and discuss its internal mechanism, which may help us better understand the general law of species diversity. Methods We investigated 208 10 m× 10 m representative quadrats in the Malan forest region on China＇s Loess Plateau. Each plot had five 2 m × 2 m subplots for shrubs and five 1 m × 1 m subplots for herbs. We recorded height and diameter at breast height （DBH） of trees and height and cover of shrubs and herbs. We determined communities and their relationships with Two Way Indicator Species Analysis （TWINSPAN） and Principal Com- ponents Analysis （PCA）. Based on species richness, Shannon-Wiener and Simpson diversity indices, the relation- ship between species diversity and vegetation organizational scales was analyzed using the additive partition approach. Important findings For the four components constituting regional diversity （α1,β1,β2 and β3） -- no matter if diversity was measured as species richness, Shannon-Wiener or Simpson indices -- within-association diversity always contributed the most to regional diversity in tree, shrub and herb layers （except species richness in the herb layer）, indicating that it was the most appropriate scale for measuring species diversity. The proportion of Shannon-Wiener diversity at the vegetation type, formation or association scales was higher than the proportion measured by Simpson diversity, which resulted from the distribution pattern of rare species on each scale. Differences among the orders of fl diversity components were observed in scales of between-vegetation type, be- tween-formation and between-association, which were mainly correlated with tree, shrub and herb layers＇ species composition and distribution in the region, as well as environmental heterogeneity among different scales.