Vegetation Activity Responses to Climate Change in the Huang-Huai-Hai Area Based on GIMMS NDVI Dataset

Based on 1982 -2003 GIMMSNDVI sounding and climate data by use o f techniques for the trend, correlation and singular value decomposition (SVD) analysis, the space and time patterns of vegetation activity response to climate change in the Huan-Huai-Hai Area (HH A) is investigated.Results suggestthat this area show s a more significant warming trend and less distinct aridization, on the w ho le, with annual mean NDVI displaying a marginally increasing trend.In the spatial distribution figure of the correlation coefficient between annual average and climate factors, the annual average temperature is positive correlated to the annual NDVI in most area, which indicates that the increasing temperature is beneficial tothe vegetation growing in most region of the study area.On the other hand, the annual precipitation isnegatively correlated to the annual NDVI in south region but positively correlated to the annual NDVI innorth region of the study area.On the yearly basis, temperature is the most sensitive climate factor.Annual temperature, rainfall and relative humidity exert positive effect on the dynamic variation in vegetationNDVI while evaporation exerts negative effect.On the seasonal scale, temperature and rainfall are themost strongly influencing factors, with autumn climate having heavier impact on yearly mean NDVI. Natural vegetation is predominantly sensitive to rainfall and, to a less degree, to temperature; agriculturalvegetation is sensitive dominantly to temperature and, to less ex tent, to rainfall.The grassland vegetationis more sensitive to the precipitation and other climate factors than other kinds of natural vegetation.Among the agricultural vegetation, the rain-fed vegetation of one cropper annual and paddy-upland rotationagricultural vegetation of two crops per annual are more sensitive to the temperature and precipitation, butthe vegetation of two crops per annual in irrigated farm land is less sensitive to the climate factors.The precipitation of autumn, spring and winter and the temperature of spring and summer are the main factors affecting natural vegetation.The temperature of spring and winter, the precipitation of spring and summerare the main climate factors affecting the agriculture vegetation.April -September vegetation response toclimate has the spatial patterns as follow s.The anomaly field of N DVI has the same structure as that oftemperature, an anti-correlation structure with anomalies of evaporation, and a see-saw distribution withpositive (negative) correlation in the north (south) with that of rainfall anomalies, and an opposite distribution with positive (negative) correlations in the south (north) to that of relative humidity.