大渡河上游地区土地利用/土地覆被变化与驱动力分析

Land Use/Land Cover Change and Driving Forces in the Region of Upper Reaches of the Dadu River

本文以1967年、1987年、2000年三期遥感资料和1∶25万数字高程模型(DEM)及多种历史文献资料为基础,分析了大渡河上游地区18665km2范围内的土地利用/土地覆被变化与驱动力。结果显示:1967～2000年,研究地区以林地为主导的覆被格局转变为以草地为主。其中,有林地面积的大幅度减少发挥着关键作用。33年间,有林地面积减少了319774hm2,所占比例从30.92%下降为13.78%。通过对景观格局变化特征的分析,尤其是有林地斑块在破碎化过程中规则性的增强,同时结合历史资料分析,论证了政策因素在该地区土地利用/土地覆被变化中所发挥的主导作用。文中应用Logistic逐步回归方法,通过空间分析,在15个生物物理和社会经济因素中筛选出对不同地类具有重要影响的关键因素,并确定了它们之间的定量关系和影响大小。

Based on remote sensing imageries of1967,1987and2000,and a digital elevation model with a scale of1 ∶ 250000,the land use/land cover change and driving forces in an area of18665km 2 in the region of upper reaches of the Dadu river are examined.The results show that the dominant land type in research area changed from forest land to grassland between1967and2000.This was mainly decrease of319774hm 2 and its proportion to total area dropped from30.92%to13.78%.Landscape pattern analysis finds out that forest patches had an increasing regularity with fragmentation process,which indicates that the decreased forest was an outcome of a planed cutting by state-owned forestry enterprises,rather than of blind cutting by local people.This point has been approved by historical documents.Therefore,it is concluded that governmental policies played a dominant role in land use/land cover change of this region.For analyzing various bio-physical and socio-economic driving forces,the method of Logistic stepwise regression is applied in our study.Through spatial analysis,the most significant drivers and their relative importance for cultivated land,forest land,grassland,water area,built-up land and unused land are founded out from such factors as terrain,elevation,roads,water system,urban and rural residential areas.