滇池流域NDVI动态变化特征及其对气候的响应

归一化植被指数（Normalized Difference Vegetation Index，NDVI）是反映森林植被变化的重要参数，分析滇池流域NDVI的变化趋势及其影响因素，对准确评估该流域近年来植被覆盖及变化情况，分析气候驱动力因素具有重要意义。采用两种数据集:中国科学院计算机网络信息中心地理空间数据云平台2000—2015年的全国合成产品；美国国家航空航天局2020—2021年的MOD13A2产品。使用趋势分析法分析滇池流域NDVI的年际和年内变化。在中国气象数据网下载1999—2015年滇池流域降水和平均气温的数据，结合NDVI数据，分别分析NDVI与降水、温度的相关关系。研究结果表明，2000—2015年间滇池流域年际和年内的春季、秋季及冬季NDVI均呈增长趋势，而年内夏季NDVI呈下降趋势。但2020年滇池流域NDVI较小，且在年内呈季节性变化趋势。滇池流域不同区域植被空间分布差异明显，整体上呈现由南向北，由西向东逐渐增大的变化趋势。NDVI较高的地区集中在流域上游，而水体及其周围地区植被覆盖较低，且水体及其周围的NDVI呈减小的趋势。滇池流域的降水量和平均温度均呈波动性变化，且2000—2015年的降水量呈明显的下降趋势。通过相应的偏相关分析发现，降水量和平均气温对NDVI均表现出正相关关系，并且相关性最强的是前期（气象因素相比于NDVI提前一个季度的时间）情况的平均气温和NDVI。总体上，2000—2015年滇池流域的NDVI在时空上呈增长趋势，但2020年滇池流域的NDVI较小；在气候响应方面，3个月前的平均气温变化对NDVI的变化起主要影响作用。 

Dynamic Variation Characteristics of NDVI in Dianchi Lake Basin and Its Response to Climate

Normalized Difference Vegetation Index（NDVI）is an important parameter to reflect change of forest vegetation.It is of great significance to analyze change trend and influencing factors of NDVI in Dianchi Lake Basin for accurately evaluating vegetation coverage and changes in recent years and analyzing driving factors of climate.Two data sets were used: monthly NDVI data of computer network information center geospatial data cloud platform from 2000 to 2015，and MOD13A2 products of NASA in 2020—2021.Trend analysis was used to analyze interannual and intra annual changes of NDVI in Dianchi Lake Basin.The data of precipitation and average temperature in Dianchi Lake Basin from 1999 to 2015 were downloaded from China Meteorological Data Network.Combined with NDVI data，correlation between NDVI and precipitation and temperature was analyzed respectively.Results showed that，during 2000—2015，the annual NDVI in Dianchi Lake Basin and in spring，autumn and winter showed an increasing trend，while annual summer NDVI showed a decreasing trend.However，the NDVI of Dianchi Lake Basin was small in 2020，and it showed a seasonal change trend during the year.On the whole，spatial distribution of vegetation in different areas of Dianchi Lake Basin was obviously different，showed a trend of increasing gradually from south to north and from west to east.The areas with high NDVI were concentrated in the upper reaches of river basin，while vegetation coverage in water body and its surrounding areas was low，and the NDVI in water body and its surrounding areas was decreasing.Precipitation and average temperature in Dianchi Lake basin were fluctuating，and precipitation in 2000—2015 was obviously declining.Through corresponding partial correlation analysis，it was found that precipitation and average temperature had a positive correlation with NDVI，and the strongest correlation was the average temperature and NDVI in the early stage （meteorological factors were one quarter ahead of NDVI）.On the whole，NDVI of Dianchi Lake Basin increased in time and space from 2000 to 2015，but it was smaller in 2020.In terms of climate response，change of average temperature three months ago played a major role in change of NDVI.