粤北岩溶山区土地石漠化过程的植被特征与多样性初步研究

Preliminary Study on Bio-productivity and Vegetation Features in Process of Rocky Desertification,North of Guangdong Province

粤北岩溶山区是广东省石漠化土地面积最大、程度最严重的区域。为了确定石漠化对植被生产力和物种多样性的影响,选择英德市岩背镇等地为研究样地,系统地调查了不同石漠化程度的植被特征和物种多样性变化,结果表明：随着石漠化程度的加深,石灰岩植被的生境向旱生化和岩生化发展,植物群落结构越来越趋于简单。植被盖度从轻度石漠化土地94.65%,降低到极重度石漠化的12.14%以下;现存生物量同样随着石漠化过程显著降低。同时,石漠化造成物种的数量和分布发生变化,物种多样性显著降低,从轻度石漠化到极重度石漠化,丰富度指数从1.61降到0.36,除从中度到重度石漠化阶段,丰富度指数都呈显著性下降趋势;Shannon-Wiener指数从轻度到中度、极重度显著下降;而Simpson指数显著增加。植被退化是石漠化发展的重要原因和标志。

Yanbei Town, which located in the north of Guangdong Province, Yingde City , is the most serious and a typical area in the rocky desertification land of Guangdong. In order to determine the impacts of rocky desertification on bio-productivity and species diversity, we selected this site as the study area, the factors of bio-productivity and species diversity were investigated in different grade of rocky desertification systematically. The results show： with the development of the rocky desertification, the territory of the limestone vegetation were replaced by some species that with more drought and more rocky, the structure of vegetation community tend to more and more simple, the vegetation coverage decreased from slight degree＇s 94. 65% to less than 12.14% in extreme degree . Standing biomass also decreased significantly in process of rocky desertification. At the same time, the species numbers and distributing were more different in the rocky desertification. In the process of rocky desertification, the Richness index values from 1. 61 to 0.36, declined significantly except from medium degree to intensity degree stage. Shannon-Wiener index values also declined significantly in the process of rocky desertification, but the Simpson index increased significantly. The vegetation degradation was the important trigger and sign of development of rocky desertification.