黄河中上游植被覆盖与人类活动强度的时空动态演化

Spatial and temporal changes of vegetation coverage response to human activity intensity in the middle and upper reaches of the Yellow River

基于MODIS-NDVI数据,采用趋势分析法、残差分析法,结合土地利用类型遥感数据及县域社会经济数据,计算人类活动强度,并在此基础上分析2000—2015年黄河中上游植被覆盖空间分布状况、时间变化趋势与人类活动强度的关系.结果表明:(1)黄河中上游地区的植被覆盖整体呈现出由东南向西北逐步减少的趋势,且存在与400 mm等降水量线基本一致的分界线.(2)退耕还林前后植被退化区占研究区域的3.65%,主要分布在经济发展程度较高的市辖区;植被改善区域占研究区域的31.12%,主要分布在陕西北部、甘肃东南部及宁夏南部;植被覆盖状况基本不变的区域占65.22%.总体来说,植被覆盖情况有所改善,但生态恢复与生态恶化并存.(3)植被覆盖状况与人类活动强度具有较高的相关性.(4)植被覆盖与人类活动强度呈现出较为同步的动态演化趋势.

In order to explore the effect of human activity on vegetation coverage,based on MODIS-normal difference vegetation index(NDVI)data,human activity intensity of land surface(HAILS)was calculated using linear regression trend analysis and residual analysis,and combined with remote sensing data of land use type and county socio-economic data.Then relationships between spatial distribution of vegetation coverage,tendency of time variation with HAILS in the middle and upper reaches of the Yellow River basin from 2000 to 2015.The results showed that vegetation coverage decreased gradually from the southeast to the northw-est,which was in consistent with the isohyet 400 mm.During the period of returning farmland to forest,vegetation degradation area in the study area accounted for 3.65%,which was mainly distributed in municipal districts with higher degree of economic development.The area with improved vegetation was 31.12%,which mainly located in the north of Shaanxi,the southeast of Gansu and the south of Ningxia.Area with unchanged vegetation was 65.22%.In general,the vegetation coverage was improved,but simultaneously ecological deterioration occurred during ecological restoration.The vegetation coverage presented a high degree of fitness with the level of HAILS.Lastly,variation in the vegetation coverage seemed to be synchronous with human activity intensity.