关键词: 川西北, 沙化, 优势种群, 空间分布格局

Abstract:

Vegetation restoration is very important to improve local environments and achieve sustainable development in sandy lands of Sichuan northwest. In this study, after an investigation on 136 samples of 1 m*1 m,a comparative study on the spatial distribution pattern of different dominant populations in desertification grassland in northwest Sichuan was made by the tests of dispersion index (ID), cluster size index (IC), Green index (GI), mean crowding index (IMC) and patchiness index (IP). Besides, the correlation analysis was used to compare the relationship of several indexes. The results showed that the patterns of those dominant populations were all aggregated distribution, however, the aggregation intensity was different on the whole. There were less community types in the exposure sandy land. Dominant populations were kobresia species and clump intensity was largest in all sandy land. There were more dominant populations in the fixed sandy land, the biggest of clump intensity was Potentilla anserina population in all dominant populations, and the least of clump intensity was Ajania tenuifoliapopulation. Clump intensity difference was observed. The clump intensity difference of the dominant populations in semi fixed sand and shifting sandy land was insignificant. Correlation analysis showed that there was a significant positive correlation among ID, ICS, GI and IMC, with coefficient almost equal to 1. It concluded that the main factors affecting the spatial distribution pattern of dominant population changed biological characteristics to soil microhabitats with the change of sand land type. It is to provide a reference to vegetation restoration of different sand land types in the northwest of Sichuan.

Key words: Sichuan northwest, Desertification, Dominant population, Spatial distribution pattern