2001—2019年云南省植被NDVI变化及其气候因子的关系

了解植被覆盖时空变化对区域环境保护及生态环境建设具有重要意义。基于MOD13Q1数据,运用趋势分析和相关分析方法,探讨了云南省植被NDVI的变化、未来趋势以及植被与气候关系的空间格局。结果表明:(1)2001—2019年云南植被NDVI均值为0.68,变化率为0.37%/a(p<0.001),空间上表现为西高东低、南高北低的特点。(2)全省Hurst指数值为0.52,植被改善的趋势在未来将持续。不同土地覆盖类型,林地、耕地植被变化的趋势为持续改善,居民地为持续退化; 草地和灌木林将由改善转变为退化。(3)近19年年平均气温和降水的变化率分别为0.03℃/a和-2.67 mm/a,两者与年NDVI之相关程度均值分别是0.26,0.21,在大部分地区表现为正相关。总体上看,气温对植被的影响大于降水。(4)植被与气温和降水的滞后响应时分别是1.9月和1.5月。月时间尺度上,植被对降水的响应更敏感。不同植被类型,林地、灌木林植被的滞后时间长于耕地和草地,森林植被最不易受短期气候变化的影响。综上,近19年云南植被NDVI呈改善趋势,未来将持续; 植被NDVI与气温和降水的相关性有着明显的地域差异。

Analysis of Vegetation NDVI Dynamic and Its Relationship with Climatic Factors in Yunnan Province During 2001-2019

It was of great significance to understand the temporal and spatial changes of vegetation cover for regional environmental protection and ecological environment construction.Based on MOD13Q1 data and methods of trend analysis and correlation analysis,the change of NDVI,the future trend and the spatial pattern of the relationship between vegetation and climate in Yunnan Province were discussed.The results showed that:(1)during the period from 2001 to 2019,the average NDVI of Yunnan vegetation was 0.68,and the annual change rate was 0.37%(p<0.001);the spatial distribution of NDVI was high in the west and south,low in the east and north;(2)the Hurst index of the whole province was 0.52;the trend of vegetation improvement would continue in the future,but there were differences among various types of land cover;the trend of vegetation change of forest and cropland would continue to improve;residential land would degrade;grassland and shrubbery would convert to degradant from improvement;(3)in recent 19 years,the annual average temperature and precipitation change rates in Yunnan were 0.03℃/a and-2.67 mm/a,respectively;the correlations between NDVI and annual average temperature and precipitation were 0.26 and 0.21,respectively;these were positive correlations in the most areas;in the whole,the influence of temperature on vegetation was greater than precipitation;(4)the lag time of vegetation change response to temperature and precipitation changes were 1.9 months and 1.5 months,respectively,the impact of precipitation was more sensitive than temperature on the monthly scale;for different vegetation types,the lag time of forest and shrub vegetation was longer than those of cropland and grassland,and forest vegetation was the least vulnerable in short-term.In conclusion,the vegetation NDVI improved significantly in Yunnan in the past 19 years.This trend would be continued in the future.The regional distribution characteristics of the correlation between vegetation NDVI and temperature and precipitation were obvious.