岷江上游半干旱河谷土地利用/土地覆盖研究

岷江上游半干旱河谷土地利用／土地覆盖结构受山地系统特征影响，以林地为主，土地利用类型分布呈垂直带性，人口增长，人民生活水平的提高以及经济政策的激发，导致耕地面积扩大，流域森林面积下降，可采资源消耗贻尽，森林面积减少，耕地面积增长是引起干旱河谷干旱面积范围扩大的重要因素，岷江上游半干旱河谷土地利用优化应以长江流域的持续发展为着眼点，突出大流域生态屏障功能，建立生态补偿机制，完善相关政策法规，以保证生态重建和土地利用结构调整工作的长期稳定性，提高土地利用方式的科技含量，在科学规划的指导下，先易后难，逐步实现生态建设与半干旱河谷的治理。

Study on Land Use/Cover in Arid Valley of Upper Minjiang Watershed

This paper focuses the land-use and land-cover of arid valley in upper Minjiang watershed. Four limitation lines related to land cover were identified. The orchards are always below the elevation of 2 000 m.The limitation altitude of cultivated-land is about 2 800 m. Forest line and grass line is about 3 800 m and 4 800 m in order. Forestland, grassland, farmland and arable land are the main types of land use/cover. From 1949 to 1998, the area of farmland has doubled. The increase of population is an important reason for the increase of farmland area. The total population has also doubled during the same period. Besides, the improvement of life standard has enhanced the demands of new farmland. As for the forestland, although the total area remains 54%, the woodland and the timber storage have decreased radically. The changes of the forestland and the farmland are the main source of negative impacts on the ecosystem of the watershed and the arid valley area. This paper has given some proposals about land-use adjustment and reforestation.