摘要:利用天山北坡2001-2015年植被生长比较旺盛月份（6-9月）的MODIS NDVI产品数据，结合像元二分法进行植被覆盖度提取，并对其空间分布特征、随时间及地形的动态变化和面积加权重心进行分析。研究表明：（1）天山北坡6-9月多年平均植被覆盖度介于0.4-0.5，以低、中低植被覆盖度为主，各等级植被覆盖度大致呈西北-东南向相间分布；（2）2001-2015年间，植被覆盖度有逐渐上升的趋势；植被覆盖改善区域（54.42%）大于退化区域（45.58%），西部较东部改善更为明显；植被覆盖度变异类型以弱变异和中等变异为主，植被覆盖度变化类型以稳定型为主；（3）天山北坡区域植被覆盖度变化受海拔高度影响明显：随着海拔高度的上升，较低植被覆盖度比例呈现先上升后下降再次上升趋势，较高植被覆盖度则与之相反；海拔3880 m以上低植被覆盖度占绝对优势，较高的植被覆盖度占比逐渐下降直至几乎绝迹；（4）各等级植被覆盖度面积加权重心集中在沙湾县、石河子市、玛纳斯县及呼图壁县；并呈现由集中到相对分散的趋势。



Abstract:Vegetation plays an important role in global environmental change. Monitoring the dynamics change of vegetation coverage is critical to a region's ecological security. With the development of 3S technology, vegetation monitoring becomes more convenient and effective. This study used MODIS NDVI data of the month (June-September) when vegetation grew vigorously from 2001 to 2015 in northern slope of the Tianshan Mountains, combined with dimidiate pixel principle to extract the vegetation coverage. Linear regression, coefficient of variation and other methods were used for the analysis of vegetation coverage dynamics. The results showed that: (1) The annual average vegetation coverage in the study area ranged from 0.4 to 0.5 in June-September, while vegetation coverage grade were mainly at low and low-medium levels. (2) During 2001-2015, the vegetation coverage tended to increase gradually and the proportion of vegetation improvement area (54.42%) was larger than that of the degraded area (45.58%). The vegetation improvement was more obvious in the west than in the east. The variation types of vegetation coverage were mainly weak variation and moderate variation, and the major change type of vegetation coverage was stable type. (3) The change of vegetation coverage in northern slope of the Tianshan Mountains was obviously affected by altitude. The proportion of lower vegetation coverage showed an increased-decreased-increased trend, while that of higher vegetation coverage was on the contrary. Low vegetation coverage in area above 3880 m occupied an absolute dominant position. (4) The area weighted gravity centers of vegetation coverage at different levels were concentrated in Shawan, Shihezi, Manas and Hutubi, which showed a trend from concentration to relative dispersion.





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