退耕还林工程影响下农林生态系统生态交错带的宽度测定
Measurement of ecotone width between agro-ecosystem andforest ecosystems after Grain for Green Program
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摘要: 生态交错带宽度的测定是定量研究其生态过程的基础,研究利用移动分割窗技术,对退耕还林工程影响下的山地农业生态系统和森林生态系统间的生态交错带宽度进行测定.首先以对生态交错带生物多样性分布趋势有较好体现的4个多样性指数(物种丰富度、Cody指数、群落相异性系数(βJ和βS))和能体现群落本质特征的重要值为指标,取平方欧氏距离(SED)和Bray-Curtis系数(PD)为距离系数,采用移动分割窗技术分析比较.结果表明,物种丰富度,群落相异性系数βJ和βS曲线趋势具有很好的重合性,同质区间也体现得较为明显,说明这3个指标生态学意义明显,有较高的实用价值;与PD相比,SED函数划分的结果要好.然后选取物种丰富度、群落相异性系数βJ和βS作为指标以及SED作为距离系数对交错带的宽度进行测定.撂荒地-云南松林交错带位置约在样带序列25~36 m处,宽度为9 m,属于急变型交错带.Abstract: To measure the eco-tone width is fundamental to the quantitative study on the ecological processes of eco-tone.In this study,Moving Split-Window Technique (MSWT) was used to measure the eco-tone width between mountain agro-ecosystem and forest ecosystem.Four indices (Species richness,Cody,Dissimilarity coefficient and Important value) had been selected,which could reflect the change of species biodiversity in eco-tone transect gradients.In addition,Squared Euclidean distance (SED) was better than Bray-Curtis percent dissimilarity (PD) for quantifying the change of species biodiversity in the eco-tone of agricultural-forest ecosystem.The results showed that the species richness was consistent with issimilarity coefficients in the eco-tone transect.It was also indicated that the width of eco-tone of agricultural-forest ecosystems was a sharp type which spanned about 9 m.
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