1999～2009年岷江上游干旱河谷聚落区林地变化特征

The Change Characteristics of Forest Land in the Settlement Niche of Arid Valley in the Upper Reaches of Min River from 1999 to 2009

岷江上游干旱河谷聚落区林地变化情况是检测长江上游生态环境建设好坏的重要指标。本文基于SPOT遥感数据和GIS技术,以聚落生态位为研究单元,分析1999~2009年岷江上游干旱河谷聚落区林地变化特征。结果显示：1）1999~2009年,岷江上游聚落生态位内林地面积增加22.58 km2,理县和汶川县增长率较高,分别为87.5%和89.75%;2）岷江上游干旱河谷聚落区林地以2 401~2 600 m为中心呈准正态分布,林地面积增加集中于海拔1 801~2 800 m地带;3）林地主要分布于15°~25°之间,不同坡段林地面积均增加,增幅介于36.31%~73.68%之间;4）林地分布呈现北坡与西坡高于南坡与东南坡的特征,受水分与湿度条件影响,北坡和西坡方向上林地增加最多,分别为64.02%和62.78%。因此,由于退耕还林等生态工程的实施,岷江上游干旱河谷聚落区生态环境得到改善。

The changes of forest land of dry valley settlement area is an important indicator of ecological environment construction in the Upper Reaches of the Yangtze River. Based on Spot remote sensing data and Geographic information systems （GIS） technology, this study took the mountainous settlement ecological niche as the fundamental research element, and considered temporal - spatial distributions and varied characteristics of forest land of dry valley settlement area in the Upper Reaches of Min River from 1999 to 2009. The results indicated that： 1 ） During 1999 -2009, the forest land in the settlement niche of Arid Valley increased by 22.58 km2 in the Upper Reaches of Min River, particularly Lixian and Wenchuan Counties had large growth rates which were 87.5% and 89.75%, respectively; 2） The forest land of dry valley settlement area took the elevation of 2401 -2600 as the center and showed quasi normal distribution, and the growth of forest area mainly concentrated in the elevation of 1801 - 2800 m ; 3 ） The forest land was mainly distributed at slope 15 -25 degrees, and all the forest lands in the different slope showed a certain growth trends, the growth rate was between 36.31% -73.68% ; 4） The spatial distribution of forest lands located with North aspect and the western aspect was higher than that located with South aspect and Southeast aspect, the maximum values appeared in northern aspect and western aspect, the values were 64.02% and 62.78%, respectively, which were influenced by moisture and humidity conditions. Therefore, due to the implementation of ecological engineering of returning farmland to forests, ecological environment of dry valley settlement area in the Upper Reach of Min River was improved.