基于MODIS数据的浙江省植被覆盖度时空变化分析

以浙江省为研究区,基于2009—2018年MODIS_NDVI数据,采用MVC最大值合成法获取逐月NDVI值,利用改进的像元二分模型估算2009—2018年植被覆盖度,结合DEM数据及《浙江省林地保护利用规划》(2010—2020年)中的林地分区,分析浙江省植被覆盖度的时空变化情况。结果表明:①2009—2018年浙江省植被覆盖度总体处于高盖度级别,存在缓慢降低的趋势。②2009年和2018年的植被覆盖度空间格局基本一致,即浙南山地区、浙西山地丘陵区>浙中丘陵盆地区、浙东沿海丘陵海岛区>浙北平原区;植被覆盖度变化以稳定为主,占总面积的62.79%,退化区域面积大于改善区域面积,退化趋势以浙北平原区最为严重,占总面积的6.73%,改善趋势以浙南山地区最为明显,占总面积的4.87%。③各地形因子范围内的植被覆盖度变化均相对稳定;不同高程范围内,明显退化区域在高程100 m以下,明显改善区域在高程200 m以上;不同坡度范围内,退化最明显区域为坡度0°,5°)范围,明显改善区域为坡度15°以上;不同坡向间,植被变化的差异并不明显。研究成果可为该地区的生态环境建设和水土流失防治提供理论依据。

Temporal and Spatial Variations of Vegetation Coverage in Zhejiang Province Based on MODIS Data

In the purpose of providing theoretical support for the eco-environment construction and soil-water loss prevention in Zhejiang Province, we estimated the vegetation coverage of Zhejiang Province in 2009-2018 using an improved dimidiate pixel model based on monthly NDVI values obtained from using MVC maximum synthesis method according to MODIS_NDVI data in 2009-2018. Moreover, in line with DEM data and the division of forest land in the Plan for the Protection and Utilization of Forest Land in Zhejiang Province (2010-2020), we probed into the spatial-temporal changes in the vegetation coverage of Zhejiang Province. Results unveiled that: 1) From 2009 to 2018, Zhejiang Province featured an overall high vegetation coverage, with a slow downward trend. 2) The spatial pattern of vegetation coverage in 2018 differed little with that in 2009. Vegetation coverage in south and west mountainous and hilly area was the highest, followed by that in central Zhejiang hilly basin area, east Zhejiang coastal hilly island area, and northern Zhejiang plain area in sequence. Areas with stable vegetation coverage accounted for 62.79% of the total area; the area of vegetation degradation was larger than the area of improvement. Vegetation degradation was most serious in the northern Zhejiang plain area, accounting for 6.73% of the total area. In particular, the south Zhejiang mountain area witnessed the most notable improvement of vegetation coverage, occupying 4.87% of the total area. 3) The change of vegetation coverage with geographical factors was relatively stable; within different elevation ranges, areas with obvious degradation were below 100 m, and obvious improvement above 200 m; within different slope ranges, areas with evident degradation were between 0° and 5°, and apparent improvement above 15°; vegetation coverage changed slightly with slope gradient.