城市化对长三角地区主要城市植被物候的影响

基于长三角地区1998—2005年NDVI时间序列影像，利用移动平均法计算了上海、杭州、南京、常州、无锡和苏州6个城市的城区与各缓冲带的平均植被物候，并分析了城区与各缓冲带平均物候的差异及其与距城区距离间的关系.结果表明，1998—2005年间，研究区的城市化导致城区内植被始绿期提前、终绿期推后、生长期变长、NDVI的年内极差减小，离城区越近的缓冲带这些变化越明显.总体看来，城市化导致城区周围4 km范围内的植被始绿期明显提前，而终绿期推后、生长期变长、NDVI年内极差减小的趋势在离城区约10 km范围内的变化显著；城区与缓冲带植被的生长期差值和NDVI年内极差差值均与离城区距离存在显著的对数关系.

Impact of urbanization on vegetation phenology in major cities in Yangtze River Delta region.

Based on the time seriesNDVI images from 1998 to 2005 and by the method of moving average, the vegetation phenology in urban areas and buffer zones of Shanghai, Hangzhou, Nanjing, Changzhou, Wuxi and Suzhou in Yangtze River Delta region were calculated. The difference of average phenology in urban areas and buffer zones was analyzed, and the relationship between this difference and the distance away from urban edge was studied. The results showed that in 1998-2005, the urbanization of the cities made the vegetations in their urban area had an earlier start of growing season (SOS), later end of growing season (EOS), longer growing season length (GSL), and smaller NDVI_amp (difference of maximal and minimal NDVI in a year). These changes were more obvious in buffer zones if they were closer to urban area. In general, urbanization made the SOS within 4 kilometers away from the urban edge started obviously earlier, and the EOS, GSL and NDVI_amp within 10 kilometers away from the urban edge changed obviously. The differences of GSL between urban and buffer zones had a significant logarithmic relationship with the distance away from the urban edge, so did the NDVI_amp.