砒砂岩区不同立地类型人工沙棘林下草本物种多样性环境解释

砒砂岩区是黄土高原区水土流失最为严重的地区之一。砒砂岩区沙棘人工林有良好的水土保持功能,沙棘林下草本植物是该人工林生物多样性的重要组成部分。目的是探明砒砂岩区人工沙棘林下草本物种多样性与环境的关系,依据生境条件的差异,沙棘林被划分为7个类型。野外调查记录了各类型所处的地形条件,采用样方法调查了每个样地草本的生物多样性,并取土样测定其养分和水分状况。采用Patrick指数、Pielou指数、Shannon指数、Simpson指数对砒砂岩区不同立地类型人工沙棘林下草本植物进行了物种多样性分析,并通过CCA、PCCA方法研究了物种分布与环境的关系。结果表明:(1)砒砂岩区不同立地类型人工沙棘林下草本层优势种不同,阴坡混交林物种数最多为23种,阳坡混交林Pielou指数最高为0.89,阴坡纯林和混交林Shannon指数均为最高,Simpson指数没有明显差异。(2)影响砒砂岩区人工沙棘林下草本物种的分布的环境因子顺序为地形因子土壤因子灌木层因子,其中坡向、坡度、土壤含水量、土层厚度、郁闭度、混交结构所占解释量较大。本研究可为当地沙棘人工林生物多样性保护和植被建设提供基础数据。

Environmental interpretation of herb species diversity under different site types of Hippophae rhamnoides forest in feldspathic sandstone region

Feldspathic sandstone regions are among the regions with the most severe soil erosion in the Loess Plateau. The planted Hippophae rhamnoides shrub forest reduces soil erosion for local residents. The herb species under the shrub canopy are important biodiversity components of this artificial ecosystem. The objective of this study was to clarify the relationship between the biodiversity of herb species and their site conditions. On the basis of the variation among sites, the planted shrub forests were classified into seven types. At each site, topography (slope, aspect, and slope position) was recorded, herb species were measured in 1×1 m² quadrats, and soil samples were collected adjacent to each quadrat. In this study, we used the Patrick, Pielou, Shannon, and Simpson indices for analysis of herb species diversity under different site types of H. rhamnoides forest in a feldspathic sandstone region, and studied the relationship between species distribution and the environment through CCA and PCCA. The following results were obtained:(1) The dominant species of the herbage layer under different site types of H. rhamnoides forest were different. The shady-slope mixed forest had the largest number of species (23). The sunny-slope mixed forest had the highest Pielou index of 0.89. The Shannon indices of shady-slope pure forest and mixed forest were the highest, whereas there was no significant difference between the Simpson indices. (2) The order of the environmental factors affecting herb species distribution under different site types of H. rhamnoides forest in the feldspathic sandstone region was terrain factor > soil factor > shrub layer factor, in which slope aspect, slope, soil water content, soil thickness, canopy density and mixed structure made the largest contributions. This study could provide a scientific basis for biodiversity protection and ecosystem development in the local region.