2000-2016年秦岭山地植被覆盖变化地形分异效应

利用2000-2016年MODIS NDVI数据，采用趋势分析及地形差异修正法，探讨秦岭山地植被覆盖变化在南北坡、不同海拔以及不同坡度坡向下的空间分异性。结果表明：近17年来，秦岭山地植被覆盖度良好，整体呈上升趋势，南北坡、不同海拔、不同坡度、不同坡向下植被覆盖度有所差异，植被变化趋势也不同。（1）就南北坡而言，近17年来秦岭南坡植被覆盖度上升趋势大于北坡，南坡植被覆盖以上升趋势为主，而北坡以稳定为主。（2）不同的海拔高度上秦岭山地植被覆盖变化在存在分异性：低海拔区域呈减少趋势，中海拔区呈明显的上升趋势，2000 m以上的高海拔区域北坡的植被覆盖度较为稳定，而南坡的2500到3100 m区域内有较明显的减小趋势。（3）从坡度来看，随着坡度的增加秦岭山地植被覆盖度由减少转为增加再转为稳定，南北坡植被变化分异性不明显。（4）不同坡向上，秦岭南北坡植被覆盖度变化差异明显，由阴坡转为阳坡时，北坡植被覆盖有明显的增长趋势，而南坡则不明显，植被覆盖度减小区在南北坡的分布呈相反趋势，分别分布在南坡的阳坡以及北坡的阴坡。

Topographic differentiation effect on vegetation cover in the Qinling Mountains from 2000 to 2016

Based on the MODIS NDVI data set for 2000-2016, we studied the spatial anisotropy of vegetation coverage change depending on north-south slopes, elevation, slope, and slope aspect by trend analysis, and the coefficient was corrected by topography. The results showed that during the past 17 years, the Qinling Mountains have had high vegetation coverage, and it will continue to increase. The vegetation coverage and its variation trend varied with topography. (1) The increasing trend in vegetation coverage was higher in the south slope than that in the north slope. The vegetation coverage in the south slope was dominated by an upward trend, whereas that in the north slope was mainly stable. (2) There was a difference in variation in vegetation coverage at different elevations. The low-elevation area exhibited a decreasing trend, whereas the mid-elevation areas showed an obvious increasing trend. The vegetation coverage was relatively stable in the north slope with an altitude of >2000 m, whereas an obvious decreasing trend was observed between 2500 and 3100 m in the south slope. (3) With the increase in slope, the trend in vegetation coverage change shifted from decreasing to increasing, and turned to stable in the steep slopes. The vegetation coverage change in the north and south slopes did not differ considerably. (4) The vegetation coverage change showed an obvious difference between the north and south slopes on different slope aspects. As the slope aspect shifted from shady to sunny, the change in vegetation coverage was obvious in the north slope, whereas that in the southern slope was not obvious. The distribution of decreased vegetation coverage area exhibited opposite trends in the north and south slopes, which are on the shady and sunny slopes, respectively.