Abstract: To explore the spatiotemporal changes and topographic effects of vegetation coverage after ecological engineering in Min County,the vegetation coverage in Min County from (1) with the implementation of ecological engineering in Min County,the overall vegetation coverage tends to be good,with 66.34% of the areas being mainly covered by high vegetation. (2) The spatial distribution of vegetation coverage showed a distribution pattern of “high in the east and low in the west,high in the south and low in the north”. High vegetation coverage areas were densely distributed in the eastern and southwestern parts of Min County,while low vegetation coverage areas were mainly distributed in the northwest. (3) The stability of vegetation coverage exhibited a spatial pattern of coexistence of high and low fluctuations,with high and low fluctuations. The proportion of vegetation improvement area was 58.76%,and degradation accounts for 30.43%,indicating that the overall trend of vegetation coverage in the study area was improvement. (4) The terrain factors had a significant impact on the spatial distribution of vegetation coverage in Min County:from the perspective of average coverage changes,the coverage in the study area is shaded slope>semi shaded slope>semi sunny slope>sunny slope. The vegetation coverage increases with altitude. As the slope increases,the average vegetation coverage in Min County showed a trend of first increasing and then decreasing,with the fastest growth rate observed in areas with slopes exceeding 25 °.

Key words: Vegetation coverage, Pixel binary model, Spatio-temporal variation, Topographic differentiation, Min County

摘要： 为探究岷县生态工程后植被覆盖度的时空变化以及地形效应，基于MODIS—NDVI数据，利用像元二分模型计算了2001—2020年岷县植被覆盖度。结果表明：(1)随着岷县生态工程的实施，植被覆盖度整体趋向良好，66.34%的区域以高植被覆盖为主；(2)植被覆盖度空间分布呈“东高西低，南高北低”的分布特征。高覆盖植被区密集分布在岷县东部及西南部，而低植被覆盖区主要分布在西北部；(3)植被覆盖度稳定性表现出“高低波动共存，低波动较大”的空间格局。植被改善面积占比为58.76%，退化占30.43%，表明研究区植被覆盖度总体变化趋势为改善；(4)地形因子对岷县植被覆盖度空间分布影响显著：从平均覆盖度变化来看，研究区覆盖度阴坡>半阴坡>半阳坡>阳坡。植被覆盖度随海拔升高而增大。随着坡度的增加，岷县平均植被覆盖度呈先增加后降低的趋势，超过25°坡度区域的植被覆盖度增长速度最快。

关键词: 植被覆盖度, 像元二分模型, 时空变化, 地形分异, 岷县