Abstract:

The simple biological model second version (SiB2 method) is used to calculate the leaf area index (LAI) of Poyang Lake basin, and analyze the annual and interannual relationship between LAI of different vegetation types and precipitation and air temperature based on NOAA/AVHRR NDVI data during 1982～2001.The results show that: in annual,LAI decreases from January to March to a minimum,then rapidly increases and reaches its maximum in July,and then begins to decrease again.The responses of LAI to precipitation and air temperature have a time lag of three month and one month respectively;in interannual,LAI of different vegetation types have no significant increase or decrease trend in 20 years, but every 2 to 3 years show an increasedecrease alternant variation.The interannual variation of LAI is mainly affected by the precipitation between May to July; in spatial,the distribution difference of LAI in spring and winter is small,only for forest covered area in the basin edge the LAI is slightly high and for the remaining large area the LAI value is very low and the distribution is relatively uniform.While in summer and autumn,the difference in the spatial distribution of LAI is large and mainly effected by the land cover types