近20年若尔盖湿地植被覆盖变化与气候因子关系研究

基于NASA提供的MODIS卫星产品MOD13Q1的归一化植被指数（NDVI）数据,利用最大值合成法及像元二分模型计算得到2000-2019年若尔盖湿地植被生长季（5-9月）的植被覆盖度。利用ERA5再分析资料月平均的2 m气温、总降水量和土壤体积含水量数据,通过趋势分析、相关分析研究2000-2019年若尔盖湿地植被生长季（5-9月）的植被覆盖与气候因子的时空分布及二者的相关程度;研究气温、降水量和土壤含水量对植被覆盖度的共同影响及各自的贡献程度。结果表明：近20年来若尔盖湿地在生长季（5-9月）的植被覆盖度略有增长;2 m气温有升高趋势,且研究区的西南部气温升高较快;研究区中南部的总降水量呈减少趋势,但不明显,在研究区中北部降水量则呈略微增加趋势;研究区北部的土壤湿度显著增加,南部则有变干的趋势。植被覆盖度与3个气候因子均呈显著的正相关关系,气候因子对植被覆盖度变化的贡献从大到小依次是2 m气温、土壤体积含水量和总降水量。

Study on the Relationship between Vegetation Cover Change and Climate Factors in Zoige Wetland in Recent 20 Years

Based on the Normalized Difference Vegetation Index(NDVI)data of Moderate Resolution Imaging Spectroradiometer(MODIS)satellite MOD13Q1 product provided by NASA, we use the Maximum Value Composite(MVC)and Dimidiate Pixel Model(DPM)to calculate the vegetation coverage of the Zoige wetland vegetation in growing season(from May to September)from 2000 to 2019. By using monthly averaged 2 m temperature, total precipitation, and soil water content data from ERA5 reanalysis data, we use trend analysis and correlation analysis method to study the spatial and temporal distribution and correlation of vegetation coverage of Zoige Wetland and climatic factors, and study the combined influence of temperature, precipitation and soil water content on vegetation coverage and their respective contributions. The results showed that the vegetation coverage of Zoige Wetland during the growing season(May-September)increased slightly in the past 20 years. The 2-meter temperature has a rising trend, especially in the southwestern part of the study area. The total precipitation in the central and southern part of the study area showed a decreasing trend, but it was not obvious. In the northern part of the study area, the precipitation showed a slight increase trend. The soil water content in the northern part of the study area increased significantly, while the southern part became dry. The vegetation coverage has a significant positive correlation with the three climatic factors. The contribution of the climatic factors to the change of vegetation coverage in descending order is 2 m temperature, soil water content and total precipitation. © 2022 Authors. All rights reserved.