基于MODIS-EVI数据的长江三角洲地区植被变化的特征

基于2001~2010年MODIS EVI植被指数产品数据，结合国家标准气象站逐月气温、降雨及日照时数资料，对长江三角洲地区植被的时空变化特征进行分析。结果表明：（1）空间分布上，该区域西南部以林地为主，而东北部以农田为主，近10 a植被变化面积占总面积的32%，以农田的转出和城镇的转入为主；（2）区域年最大EVI整体呈减少趋势（-0028/10 a），不同季节下，夏冬季均呈减少趋势（以2月和8月份最为显著），春秋季则呈增加趋势（以5月和10月份最为显著）；（3）不同植被类型下，城镇和农田EVI呈不同程度减少趋势，以城镇EVI下降速度(-0076/10 a）最为显著（R2=077），而林地变化较弱；(4)研究区湿润气候环境下，农田和林地年最大EVI与日照时数和气温多呈正相关性，与降雨多呈负相关性，其中以林地EVI与2~4月份日照时数的正相关性较为显著，城镇EVI与气象因子的关系相对较弱，更多的是受城镇化等人类活动的影响

ANALYSIS OF THE VEGETATION CHANGE IN THE YANGTZE RIVER DELTA BASED ON MODIS-EVI TIME SERIES DATA

Based on the 2001-2010 MODIS EVI data and meteorological data including temperature,rainfall and sunshine hours data,this paper studied the dynamic change of vegetation in the Yangtze River Delta by using statistical method.The results are as follows.① The southwest of the region was covered by forest,the northeast part was dominated by cropland,the central part was urban agglomeration.From 2001 to 2010,the region witnessed an increase in urban at the expense of cropland and forest,with the total conversion area accounting for 32% of entire area.② Due to the rapid urbanization,the vegetation index(EVI) had showed a slightly decreasing trend in the whole region,with an average rate of 0028 every 10 years.For the seasons,EVI in the summer and winter tended to decrease (especially in August and February),while spring and autumn showed an increasing trend (especially in October and May).③ For different vegetation types,the urban showed the largest decreasing trend(-0076/10 a,R2=0.77）,while slightly decreasing trend for cropland and little for forest.④ The annual maximum EVI of forest had the strongest correlation with the sunshine hour from February to April.Thermal factors (i.e.temperature and sunshine hours) were the main climatic factors affecting the vegetation growth,while the rainfall had a negative correlation with EVI due to the humid climate in the region.EVI had weak correlation with climatic factors mainly for human activities in urban region