基于MODIS-EVI的2000～2015年重庆植被覆盖季节变化

SEASONAL VARIATION OF VEGETATION COVERAGE BASED ON MODIS-EVI DATA IN CHONGQING DURING 2000-2015

基于2000~2015年的MODIS-EVI数据,采用MVC、趋势分析和分布指数法,分析了重庆近16 a来植被的季节变化趋势和空间分布特征。结果表明:(1)植被减少类型冬季比例最高(6.33%),主要分布于受库区蓄水和建设用地扩张影响的河谷、城镇及其周边地区;植被不变类型秋季比例最高(88.23%);植被增加类型春季比例最高(31.50%),主要分布于农业种植的西部丘陵区和中部平行岭谷地区。(2)植被变化类型优势分布区域各异,植被减少主要分布于小于400 m、小于6°区域,植被增加主要分布于400~1 000 m、6°~15°区域,在大于1 000 m、大于15°区域植被相对稳定。(3)从春季到夏季,植被减少类型向低地形区(<800 m,<6°)移动,而植被增加类型则向高地形区(>800 m,>6°)移动;从夏季到秋季,植被减少类型向高地形区(>500 m,>6°)移动,而植被增加类型则向低地形区(<500 m,<6°)移动;从秋季到冬季,植被减少和增加类型均在向高地形区移动,在高地形区,植被减少(>1 300 m,>15°)分布强于植被增加(>500 m,>6°),在低地形区则是植被减少(<1 300 m,<15°)分布弱于植被增加(<500 m,<6°)。(4)在坡向的分布上,除了平地区域外,植被变化幅度在北、东、南、西坡向上随季节变化不明显。

Seasonal change and spatial distribution pattern of vegetation in the Chongqing region was studied using the distribution index method and the MODIS-EVI data during 2000-2015. The results showed that： （1） vegetation reduction presented the highest proportion（ 6.33% ） in winter. The reduction was mainly distributed in the valleys, towns and surrounding areas influenced by the reservoir construction and built-up expansion. Stable vegetation presented the highest proportion （88.23%） in autumn. Vegetation increase presented the highest proportion（31.50% ） in spring. The increase was mainly distributed in the west hilly region and farming areas in the middle parallelism valley. （2） The areas with dominant vegetation changes are different. Vegetation reduction was mainly distributed in the areas below 400 m elevation and below 6° slope. Vegetation increase was mainly distributed in the areas between 400 and 1 000 m elevation and between 6°and 15° slope. Stable vegetation was mainly distributed in the areas above 1 000 m elevation and above 15° slope. （ 3 ） From spring to summer, vegetation reduction moved to lower terrains（ 〈 800 m elevation, 〈 6°slope）, but vegetation increase moved to higher terrains（ 〉 800 m elevation, 〉 6° slope）. From summer to autumn, vegetation reduce moved to higher terrains（ 〉 500 m elevation, 〉 6° slope）, but vegetation increase moved to lower terrains（ 〈 500 m elevation, 〈6° slope）. From autumn to winter, vegetation reduction（ 〉 1 300 m elevation, 〉 15° slope） was stronger than vegetation increase（ 〉 500 m elevation, 〉 6° slope） on the high terrains. Vegetation reduction（ 〈 1 300 m, 〈15°） was weaker than vegetation increase（ 〈 500 m, 〈 6°） on the low terrains. （4） On the distribution of aspect, vegetation change extent did not present significant seasonal variation across the North, East, South and West directions.