小尺度下幂乘方模型在天然草地空间分布研究中的应用

本研究以陕西省神木县尔林兔镇分布的3种不同类型的天然草地群落为研究对象，通过在每种草地群落内设置两条样线作为重复验证幂乘方模型在草地群落植物种空间分布规律研究中的可利用性，并利用该模型探明3种类型天然草地群落的空间分布状况。结果表明：同一种草地群落中，两条样线重复调查得到的所有植物种出现频率的空间分布对幂乘方模型均具有很好的吻合性，且两条样线的幂乘方模型回归直线间均无显著性差异（P>0.05），群落整体处于异质性分布；两条样线中植物种出现频率（p_i）与空间异质性指数（δ_i）之间均呈正向的对数相关关系（P<0.01），且无显著性差异（P>0.05）；3种类型的天然草地群落整体均呈现空间异质性分布，异质性程度依次为：滩地草地 > 梁地草地 > 油蒿灌丛草地；且随着物种多样性指数（H'）的增大，空间异质性指数（δ_i）均增大。

Application of Power Law Model in the Study of Spatial Distribution of Different Types of Natural Grasslands Under Small Scale

This study took three different types of natural grassland communities distributed in Erlintu Town,Shenmu County,Shaanxi Province as research objects. The availability of the power model in the study of the spatial distribution rule of plant species in grassland communities was verified by setting two transect lines as repetitions in each grassland community. The model was used to investigate the spatial distribution of three types of natural grassland communities. The results showed that the spatial distribution of the occurrence frequency of all plant species in the same grassland community obtained from the repeated investigation of two transect lines was in good agreement with the puissance model. There was no significant difference (P>0.05) between the puissance model lines of the two transect lines,and the whole community was in heterogeneous distribution. There was a positive logarithmic correlation (P<0.01) between plant species occurrence frequency (p_i) and spatial heterogeneity Index (δ_i) in two transect lines,and there was no significant difference (P>0.05) in the obtained relationship curves. The three types of natural grassland communities all showed spatial heterogeneity distribution. The degree of heterogeneity was as follows:Beach grassland > highland grassland > Artemisia ordosica shrub grassland. With the increase of species diversity index(H'),spatial heterogeneity index (δ_i) increased.