The Change of Green Wave and Brown Wave of the Vegetation in Huanghe-Huaihe-Haihe Zone and its Responds to Climate Changes

The article, using the each ten day´s data of NOAA/AVHRR from 1981 to 2000 and adopting the Maximum-Slope method, Curve-Fitting method and stepwise regression, analyzes the beginning and ending of the growth season of the vegetation in the Huanghe-Huaihe-Haihe (HHH) zone. Meanwhile, the pixel by pixel NDVI map is worked out with typical bands as the sample. The article, through researching on the change of green wave and brown wave, reveals the changing rules of vegetation activities and its responds to climate changes in the past 20a. According to the researches, the growth season in HHH zone starts at the last 10 days of March and ends at the first 10 days of November on average. The average NDVI for the vegetation in the researched area is generally increasing, especially in spring. With the time passing by, the green wave of the critical value of the growth season in the area changes from south to north, while the emergence of brown wave prolongs from north to south. As the main respond of the vegetation activities in the study area to climate changes, the growth season of the vegetation happens ahead in HHH zone.