温带大陆性半干旱季风气候区植被覆盖度时空变化及其地形分异研究

以内蒙古大青山为研究区,基于4期TM/OLI影像,提取NDVI,采用像元二分模型,计算植被覆盖度,探测温带大陆性半干旱季风气候区2000-2017年间植被覆盖度的分布格局、动态变化及其地形分异规律。研究结果表明：（1）研究期间,随着研究区从经济开发到国家自然保护区功能规划的改变,植被覆盖度先降低后升高,整体上趋向良好,平均有64.19%的区域以中高植被覆盖度为主。（2）植被覆盖度空间格局总体上呈"东高西低,南高北低"的分布特征。中高植被覆盖度集中在大青山呼和浩特段南部和乌兰察布段,而低植被覆盖度主要分布在西段山体。（3）研究期间,研究区32.46%的植被覆盖度得以改善,12.92%的植被退化,表明研究区植被覆盖度总体改善。（4）地形因子对研究区植被覆盖度分布格局影响显著：植被覆盖度随海拔升高呈增加趋势,在2000-2296m高程带最高。植被覆盖度与坡度正相关,坡度越高,植被覆盖度越大。植被覆盖度在不同坡向上差异明显,总体上呈现阴坡 > 平地 > 阳坡的分布规律。

Temporal and spatial changes of vegetation coverage and its topographic differentiation in temperate continental semi-arid monsoon climate region

Taking Daqing Mountain in Inner Mongolia as the research area, we extracted the Normalized Difference Vegetation Index (NDVI) based on four TM/OLI images. The dimidiate pixel model was used to calculate vegetation coverage. The distribution pattern, dynamic changes and terrain differentiation of vegetation coverage were detected in temperate continental semi-arid monsoon climate zone from 2000 to 2017. The results showed that: (1) during the study period, the functional planning of the study area was changed from economic development to national nature reserve. With the change, vegetation coverage decreased and then increased, tending well overall. The average area of 64.19% was dominated by medium-high vegetation coverage. (2) The spatial pattern of vegetation coverage was generally characterized by the distribution of "high east and low west, south high and low north". The mid-high vegetation coverage was concentrated in the southern part of Hohhot section and Wulanchabu section of Daqing Mountain, while the low vegetation coverage was mainly distributed in the western section of the mountain. (3) During the study period, 32.46% of vegetation coverage in the study area was improved and 12.92% of vegetation was degraded, indicating that the vegetation coverage in the study area improved overall. (4) The topographic factor had a significant impact on the vegetation coverage distribution pattern in the study area. Vegetation coverage increased with altitude, and was the highest in the 2000-2296 m elevation. Vegetation coverage was positively correlated with slope, and the higher the slope, the greater the vegetation cover. Vegetation coverage was significantly different in different slope directions. The overall vegetation coverage shows the distribution that shady slope is larger than flat land and flat land is larger than sunny slope.