Study on the Relation between Extreme Climate Index and NDVI Change of Vegetation: A Case Study of Naoli River Basin in Sanjiang Plain

• 1、College of Wildlife Resources, Northeast Forestry University, Harbin 150040

Abstract：The extreme climate events caused by global climate change are frequent, and the response of vegetation growth of different land use types to extreme climate in the basin is the purpose of this study. Normalized Differencevegetation index (NDVI) can better reflect the growth of vegetation. This paper uses MODIS monthly data to obtain the annual and monthly mean, maximum and minimum values of NDVI for four different types of vegetation in croland, paddy field, forest and wetland land use from 2000 to 2017. The 11 extreme climates of two meteorological stations (Baoqing Station and Fujin Station) in the Naoli River Basin for more than 60 years are calculated. Using correlation analysis and random forest regression method, the response of different vegetation NDVI to extreme climate in Naoli River Basin was analyzed. The results showed that the NDVI of forest vegetation in Naoli River Basin was the highest and that of croland was the lowest. The NDVI of four vegetation types was positively correlated with extreme temperature index TNn (Min Tmin), TXn (Min Tmax), TNx (Max Tmin) and TXx (Max Tmax) and extreme precipitation index RX5Day (Max 5-day precipitation amount) and RX1Day (Max 1-day precipitation amount)are positively correlated, the NDVI is only negatively correlated with DTR(Diurnal temperature range); the results of random forest models indicated that cropland, paddy fields and wetlands are greatly affected by extreme warm and extreme humidity indices, while for forests they are mainly affected by extreme cold and extreme warm indices.)

Keywords： Environmental Geography and Ecology Naoli River Land Use Type NDVI Extreme Climate