基于时序指数西北植被物候时空变化特征

基于1999—2010年SPOT VEGETATION旬数据，采用HANTS方法对原数据进行平滑处理，并利用傅里叶插值方法将旬数据插值成天数据，再通过NDVI天变化量确定植被物候期，研究了中国西北植被物候时空特征。结果表明:（1）海拔2 km以下，植被类型以农业植被为主，受人类因素影响较大，物候生长季始期（SOG）相对提前，生长季末期（EOG）推迟，生长季长度（LOG）变大且由东南向西北递减；在海拔较高地区，物候SOG推迟，EOG提前，LOG缩短。（2）1999—2010年西北植被物候，东部SOG提前，EOG推迟，LOG变延长；而向西部物候变化特征与东部相反。一方面，从陕西到青海海拔不断上升，温度逐渐下降，植被物候也随之变化；另一方面，陕西一带是集中农业区，青海地区主要以草地植被为主，农业（小麦）植被物候期相对较长。

Characteristics of Vegetation Phenology in Northwest China Based on Sequential Vegetation Index

Based on 10-day data of the SPOT VEGETATION from 1999 to 2010, using HANTS method to smooth the original data and convert them into daily data throughout Fourier interpolation method, we investigated the space-time characteristics of vegetation phenology in the northwest region of China. The results are shown as follows. (1) Below the altitude of 2 000 meters, vegetation type was given priority to agricultural vegetation and was greatly influenced by human factors. The start of growth (SOG) was relatively early. The end of growth (EOG) appeared delay. The length of growth (LOG) extended, and descended from southeast to the northwest areas. In the high altitude areas, the SOG appeared delay. EOG appeared in advance and the trend of LOG was shortened. (2) From 1999 to 2010, the SOG appeared in advance, EOG delayed and the LOG extended in the eastern area. The change of phonology in western area was contrary to that of the eastern area for many years. On the one hand, the altitude rose from Shaanxi to Qinghai. The temperature gradually decreased and the vegetation phenology changed. On the other hand, agricultural areas focused on Shaanxi and the grass grew in most regions of Qinghai. The main vegetation in Qinghai is grass, and the agricultural crop (wheat) phenology period was relatively long in that area.