Response of Vegetation to Extreme Temperature in the Three Gorges Reservoir Area

Based on the daily meteorological data of the highest temperature, lowest temperature, average temperature data from 22 meteorological stations, normalized vegetation index data (NDVI) and vegetation type data in the Three Gorges reservoir area from 2000 to 2019, this paper analyzed the asymmetric change of extreme temperature during day and night in the Three Gorges reservoir area, and its dynamic effects on vegetation using the RClimDex extreme weather index model, trend analysis and Pearson's correlation analysis method.. The results showed that: (1) Over the past 20 years, the change range of extreme temperature index at night was greater than that during the day in the Three Gorges reservoir area; (2) The response of vegetation to the extreme temperature index at night was more pronounced than that during the day; (3) Different vegetation types had different correlations with the extreme temperature during the day and night. Two cold indexes, TX10p and TN10p, played obstructive roles on vegetation growth, especially on coniferous forest and grass. TX90p and TN90p had positive effects on the growth of all vegetation types, and TN90p had more positive effects, especially on broad-leaved forests, cultivated plants, and grasses.