基于土壤养分的农林生态系统生态交错带宽度测定

Measurement of eco-tone width between agro-forest ecosystems based on soil nutrients

生态交错带变化最显著的是物种组成和植被结构,然而植物群落与土壤养分是相互制约相互促进的两个系统。前期利用植物物种多样性变化趋势测定出退耕还林政策驱动下,退耕撂荒地—云南松林(Pinus yunnanensis Franch)交错带宽度约9 m。假设利用土壤养分变化与前期利用植物物种多样性变化测定出的生态交错带宽度和类型一致。为验证此假设,选取滇西北维西县永春乡退耕还林政策下形成的退耕撂荒地—云南松林交错带为研究对象,测定其土壤养分变化趋势,并利用移动窗口法进行交错带位置和宽度的测定。结果表明:(1)相对于云南松林,退耕撂荒地土壤养分含量(有机质,碱解氮,速效钾,速效磷)均显著偏低;(2)pH,有机质,碱解氮的变化趋势能更好的用于测定交错带的位置和宽度,且SED指数优于PD指数;(3)最终测定农林生态交错带的宽度为11 m,属于急变型交错带,与前期利用植物多样性变化测定的结果一致。

The most significant changes of ecotone are species composition and vegetation structure, but plant community and soil nutrients are two systems that are mutually restriction and promotion. In a previous study, we found the width of ecotone between abandoned land and Yunnan pine forest was about 9 m, according to the gradient of plant species diversity. In this study we measure the width of ecotone based on soil nutrients and examine whether the results are consistent with those based on plant species diversity. This study was conducted at Yong Chun township, Weixi county, northwest of Yunnan Province. We first record the gradient of soil nutrients along the ecotone between abandoned land and Yunnan pine forest. The moving split-window technique（MSWT） is used to assess the ecotone width. The results show that：（1）The soil nutrient contents（Organic matter, available N, available K, available P） in abandoned land are significant lower than those in pine forest;（2）Some parameters, i.e. pH, Organic matter, and available N, are better to locate and measure the width of ecotone, and squared euclidean distance（SED） is better than Bray-Curtis percent dissimilarity（PD） for quantifying the gradient of soil nutrients across the ecotone;（3）The width of ecotone is spanned about 11 m and is a sharp type. These results are consistent with those based on plant species diversity.