陕西省植被退化及其驱动因素分析

Analysis of vegetation degradation and its driving factors in Shaanxi Province

基于2000—2013年250 m分辨率MODIS NDVI数据,运用混合像元分解模型计算植被覆盖度,评价陕西植被退化情况,分析引起植被退化的主要因素,为进一步开展生态、城镇建设规划提供依据。结果表明:1)陕西省植被退化区域主要分布在以西安市为主的关中城市群和榆林市以北的沙漠地带。植被退化面积最多的市是西安市,其次是榆林市,最少的是安康市。2)植被变化以改善和变化不明显为主,分别占土地总面积的48.03%和49.10%;植被退化面积较少,占土地总面积2.87%,其中轻度退化、中度退化和重度退化的面积分别占总土地面积的1.39%、0.56%和0.92%。3)植被退化主要发生在农田,占总退化面积的54.36%。4)植被退化面积与新增建成区面积的关系达到极显著程度,说明随着城镇化的不断发展,城镇用地不断扩张,大量农田、森林、草地等植被覆盖度高的土地被占用,直接导致植被退化,因此在城镇规划中应重视绿地园林建设;榆林市以北的沙漠地带局部区域植被仍在退化,应继续保护治沙成果和治理裸露沙地。

Based on the MODIS NDVI data of 250-m resolution during the period of 2000-2013, the mixed pixel decomposition model was employed to calculate vegetation coverage and evaluate vegetation degradation situation in Shaanxi Province, in order to analyze the main factors causing the degradation of vegetation and to provide a basis for ecological construction and the planning of urban construction. The results showed that： 1 ） The degradation areas of vegetation in Shaanxi Province were mainly distributed in the Guanzhong urban agglomeration, especially in Xi＇ an City and the desert belt in the north of Yulin City. Xi＇ an City was the city with the greatest vegetation degradation area, followed by Yulin City, and Ankang City had the least area. 2） The vegetation was mainly improved or not significantly changed, accounting for 48.03% and 49.10% of the total land area, respectively. The vegetation degradation area was smaller, accounting for 2.87% of the total land area, of which the areas of mild, moderate and severe degradation accounted for 1.39%, 0.56% and 0.92% of the total land area, respectively. 3 ） Vegetation degradation occurred mainly in the farmland, accounting for 54.36% of the total degradation area. 4） The re- lationship between the vegetation degradation area and newly increased built area reached a sig- nificant level, indicating that the continuous development of urbanization came with the occupa- tion of the farmland, forest and grassland with high degrees of vegetation coverage, thus directly leading to the degradation of vegetation. Therefore, attention should be paid on green space land- scape construction in urban planning. Some vegetation in the desert region of the north of Yulin City continued to degrade, and desertification control should be continuously maintained.