Based on the 2000-2015 MODIS⁃NDVI remote sensing data, spatio⁃temporal variation of land vegetation cover in Gansu Province was explored with the aid of the GIS technology, and linear regression analysis methods. Then, on such a basis, the relationship between vegetation coverage and the total area involved in the Grain⁃for⁃Green project was ana⁃lyzed. Results show that the annual NDVI value of Gansu Province continued to increase during the study period, with an annual growth rate of 0�43%, indicating that vegetation coverage was generally improved in Gansu Province. Although veg⁃etation coverage in some regions still showed a decreasing trend, the areas with vegetation coverage improving formed the majority of the province. Among them, the highly⁃improved regions, moderately⁃improved regions, and slightly⁃improved regions accounted for about 20�62%, 14�67% and 33�05% of the province in area, respectively, while the regions with vegetation cover degrading only held 2�87%. In general, however, the total effective vegetation coverage in Gansu is still lower, compared with many other provinces in China, with the mean of 16 years being only 50�98%. The areas medium and low in vegetation coverage in total accounted for over half of the total area, and unevenly distributed. The southeast part of the province was the highest in vegetation coverage, reaching 75�43%, followed by the central part and the north⁃west part, with coverage of 47�84% and 31�77%, respectively, indicating that the distribution of vegetation cover varied spatially in the province. The area of lands involved in the Grain⁃for⁃Green project better explains the changes of vegetation coverage. The annual mean vegetation coverage of the years from 2000-2015 of the province was significantly related to the area of lands affected by the“Grain for Green” project in the region east to the Yellow River, with a determination coeffi⁃cient of 0�721 8.%利用2000—2015年MODIS⁃NDVI数据，基于遥感和地理信息系统技术，采用像元二分法和一元线性回归分析法，定量探讨了甘肃省近16 a植被覆盖的时空变化特征，并在此基础上评估退耕还林面积与植被覆盖的相互关系。结果表明：（1）2000—2015年甘肃省年均归一化植被指数（NDVI）值呈增加趋势，年增长速率为0�43％，说明甘肃省植被覆盖总体呈改善态势。（2）16 a间，全省植被覆盖虽有局部恶化趋势，但改善区域面积远大于植被退化区域。其中，明显改善、中度改善和轻微改善区域面积分别占总面积的20�62％、14�67％和33�05％，退化区域面积仅占2�87％。（3）总体上，甘肃省植被覆盖度仍然较低，全省16 a平均植被覆盖度为50�98％，低、中低植被覆盖区面积占总面积的50％以上，且分布不均，其中东南地区平均植被覆盖度最高，为75�43％，中部次之，为47�84％，西北最低，只有31�77％，空间差异显著。（4）退耕还林面积能较好地解释植被覆盖度的变化。退耕还林工程集中区即黄河以东地区累计退耕还林面积与2000—2015年年均植被覆盖度明显相关，其决定系数R2为0�7218。
展开▼
