基于NDVI的三北防护林工程区植被覆盖度变化图谱特征

Spectrum Characteristic of Vegetation Coverage Change Based on NDVI in the Three-North Shelter Forest Program

基于1985、1995、2000、2010年4期GIMMS NDVI3g数据,利用像元二分模型估算植被覆盖度,并运用图谱分析法对三北防护林工程区4期植被覆盖度变化进行了时空分析。结果表明:(1)图谱空间差异上,植被覆盖度变化主要发生在内蒙古东北部、新疆西北部以及陕甘宁地区,且在工程区内先分散再集中;(2)图谱数量变化上,植被覆盖度变化的总面积先减少后增加,总体呈现出上升趋势;(3)图谱变化模式上,以稳定型、最近转换型和平稳转换型为主,而变化最大的图谱单元类型大部分是植被覆盖度等级转好的类型,植被覆盖度呈现稳定增长的态势,尤以2000-2010年最明显。研究结果可以及时准确地反映该工程区植被变化状况,为三北防护林工程进一步建设提供科学指导。

Based on the GIMMS NDVI3g data of 1985, 1995, 2000, 2010 and using the dimidiate pixel model to calculate the vegetation coverage, spatial-temporal characteristic of vegetation coverage change was analyzed by the spectrum analysis in the Three-North Shelter Forest Program. The results showed that, for differences of the spectrum space, the change of vegetation coverage occurred mainly in the northeast of Inner Mongolia, in the northwest of Xinjiang, the Shaanxi-Gansu- Ningxia border region, and the trend of vegetation coverage change was from scattered to be centralized in area of the project. For variations of spectrum quantity, the area of the vegetation coverage change increased after the first decreased, showing a rising trend in general. For the mode of spectrum change, the stabilization, recent conversion and smooth transition were primary, and the biggest changing spectrum unit was mostly the types that vegetation coverage level had turned good, presenting the trend of steady growth, especially from 2000 to 2010. Research results could timely and accurately reflect vegetation change, which will provide a scientific basis for further construction of the Three-North Shelter Forest Program.