基于RS的北京门头沟植被覆盖时空演变研究

Research on Vegetation Coverage Evolution of Mentougou District by Remote Sensing

应用RS技术,以1979年和2005年的Landsat TM影像为数据源,并对其进行边界修补、去云处理、地形校正、大气辐射订正和反射率计算,然后运用归一化植被指数和改进的像元二分模型,分别计算其归一化植被指数ND-VI及植被覆盖度,对北京市门头沟区的植被覆盖进行动态遥感监测。结果表明:(1)门头沟区植被覆盖整体呈下降趋势,覆盖度从1979年的76.4%减少为2005年的72.7%;(2)覆盖度在60%以上的区域比较稳定,是植被覆盖的主体;(3)覆盖度在80%以上的大面积减少,说明该区植被破坏严重,这与城市化进程的加快、对土地大规模利用、经济增长有很大关系;(4)由于居民点建设中采沙、采石和采煤占用绿地,永定、龙泉、谭柘寺植被退化最严重;军庄退耕还林和果林绿化是唯一植被覆盖增加的乡镇。其它乡镇植被退化平均在5%以内,妙峰山、王平、大台、斋堂四个中部乡镇由于采矿、采石等人为活动,特别是京西矿业集团的煤矿多基本集中在此,使这4个乡镇植被退化明显,并已形成采空区和塌陷区;雁翅、清水乡植被退化主要以自然退化为主,退化幅度相对较小。

In this paper,we chose two TM images of 1979 and 2005 as the data source.After boundary fixing,cloud processing,topographic correction,atmospheric radiation correction,and reflection calculation,based on normalized difference vegetation index and improved pixel binary model,we calculated NDVI and vegetation coverage of these two images,and dynamically monitored the vegetation cover changes of Mentougou district in Beijing.The results showed that：（1）the vegetation coverage showed a downward trend,reduced from 76.4% in 1979 to 72.7% in 2005;（2）the area with coverage more than 60% is relatively stable,which is the main area of this district;（3）the area with coverage over 80% was largely decreased,indicating that there was severe damage to vegetation coverage in these area,the reason must be the rapid urbanization,the large-scale land use and the rapid economic growth;（4）Yongding,Longquan,Tanzhesi,these three towns＇ vegetation has severe degraded because of the sand mining,quarrying and mining.Junzhuang is the only town whose vegetation coverage increased,the reason is to return farm land to woodland and fruit trees planting.Because of human activities such as mining and quarrying,the vegetation coverage shows a clear degradation of Miaofengshan,Wangping,Datai and Zhaitang,especially the Beijing West Coal Mining Group focus on these four towns.The coverage shows a relatively small degradation,and the natural degradation is dominant in Yanchi and Qingshui.