Spatial and Temporal Variations of the Vegetation Growing Season in Warm-temper ate Eastern China during 1982 to 1999
1982~1999 年我国东部暖温带植被 生长季节的时空变化

Phenological observation data of plant communities from 1982 to 1996 at 5 sites and a method for phenological cumulative frequency modeling were used to determine the beginning dates of local phenological seasons and their corresponding threshold values of normalized difference vegetation index(NDVI) in each year.Then,a year-type cluster analysis of NDVI profiles at each phenological station during 1982 to 1999 and a spatial cluster analysis of NDVI profiles for all of the pixels within the study area year by year were employed to fulfill a spatial-temporal extrapolation of vegetation phenological seasons.Consequently,we obtained spatial-temporal patterns of the beginning date of vegetation phenological seasons and the length of the vegetation growing season in the deciduous broad-leaved forest area of warm-temperate eastern China from 1982 to 1999.The results show that(1) the annual mean beginning dates of vegetation phenological seasons and the mean lengths of the vegetation growing season indicate changes of a spatial pattern mainly following latitude and altitude;(2) the beginning dates of the phenological spring dominate a significantly advanced trend over the entire area during 1982 to 1999,especially in North China Plain,whereas the beginning dates of the phenological summer,autumn and winter dominate a significantly delayed trend,also mainly in North China Plain,which causes a significant lengthening of the vegetation growing season in North China Plain;(3) linear trends of the beginning dates of vegetation phenological seasons are consistent with linear trends of seasonal air temperatures in North China;(4) the vegetation growing season lengthening revealed by the current study is consistent with the phenological growing season lengthening of the individual tree species in Europe,and the satellite-derived growing season lengthening in Eurasia and temperate China.