黄土丘陵区退耕地植被景观时空变异特征

Spatio-Temporal Variance of Vegetation Index of Cropland to Forest and Grass in Loess Hilly Region

对黄土丘陵区退耕地植被特征的时空变异性进行了研究。结果表明,不同植被类型区植被特征之间差异不是很显著,仅延安与安塞在物种丰富度之间和安塞与吴旗在物种多样性之间存在较显著的差异(0.01<p<0.05),其它的两两之间的差异并不明显。延安森林带北缘→安塞森林草原带植被指数呈下降趋势,降幅最大为17.65%,变异系数呈增大趋势,增幅最大为21.49%;安塞森林草原带→吴旗草原带物种丰富度指数及其变异系数都呈增大趋势,而物种多样性和均匀度指数呈减小趋势,其变异系数呈增大趋势。植被指数随退耕年限的变化趋势图都有两个明显的峰值,并在退耕20年左右后植被群落逐渐稳定。

Vegetation is one of the most active factors of landscape and the important content of evaluation for cropland to forest.The relationship between different vegetation styles is central to ecological research.In the loess hilly region,study of vegetation characteristics is required for understanding of landscape ecological processes and restoration of cropland to forest.Spatio-temporal variance of(vegetation) species richness,diversity,evenness of cropland to forest of different vegetation characteristics in the loess hilly region are analyzed in this paper.The results showed no significant differentia between were observed in two vegetation index,expect species richness between Yan'an and Ansai and species diversity between Ansai and Wuqi come to significant differentia.Since north of forest zone in Yan'an to forest-grass zone in Ansai,vegetation index presented digressive trend and its maximal depressed extent was 17.65%.Coefficient of variance presented ascensive trend and its ascending extent was 21.49%.Since forest-grass zone in Ansai to grass zone in Wuqi,species richness index and its coefficient of variance both showed ascensive trend,but species diversity and evenness showed digressive trend and theirs coefficient of variance showed ascensive trend.Vegetation community was step by step steady after 20 years of cropland to forest and grass.