1987～2015年嘉陵江源区植被覆盖度时空变化特征

江河源头地区植被建设与生态保护意义重大。应用遥感技术分析植被覆盖状况近年来已渐成热点。本文以嘉陵江源头所在地陕西省宝鸡市凤县为研究区，基于1987年、2000年和2015年3期Landsat卫星遥感影像，提取归一化植被指数NDVI（Normalized Difference Vegetation Index），采用像元二分模型，运用ENVI 5.3和ArcGIS10.4软件计算得到研究区植被覆盖度分布格局及动态变化。结果表明：（1）1987~2015年期间研究区植被以高覆盖区为主，高覆盖区面积增加了5.96%，呈上升趋势；（2）研究区植被退化面积占3.91%，基本不变的面积占85.36%，改善面积占10.73%，研究区植被改善面积多于退化面积，与退耕还林还草工程关系密切；（3）植被覆盖度随坡度和高程的增大呈先增加后降低的趋势；阴坡的植被覆盖度低于阳坡，但高于平地，坡向对植被覆盖的影响主要体现在温度上；（4）矿产资源开发对植被破坏的影响大于风力发电场建设，建议当地政府加强矿山生态环境修复力度。研究结果可服务于嘉陵江源区生态保护与流域管理。

Spatial-temporal Dynamics of the Fractional Vegetation Coverage in the Headwaters of the Jialing River from 1987 to 2015

In order to generate information for monitoring spatial-temporal variations of the fractional vegetation coverage (FVC) in the headwaters of the Jialing river, the normalized difference vegetation index (NDVI) derived from Landsat remote sensing images (1987, 2000 and 2015 year) and the dimidiate pixel model were conducted in the Feng county of the Baoji city, Shaanxi province, using ENVI 5.3 and ArcGIS10.4 software. The results showed that:(1) the high vegetation coverage area had a dominant proportion and its area had increased by 5.96% from 1987~2015 in the study zone; (2) the vegetation coverage in 85.36% of the study zone was unchanged, proportions of vegetation improvement area and vegetation degradation area in the study zone were 10.73% and 3.91%, respectively, and the former greater may be resulted from the effort of returning farmland to forest and grassland in the past 29 years; (3) as the slope angle and elevation increasing, FVC showed a variation pattern of starting with an increasing trend and then turning into decreasing, FVC of shady slope was slightly lower than that of sunny slope but higher than that of flatland, indicating that temperature played an important role in the influencing of the slope aspect to FVC; (4) the destructive effect of exploiting mineral resources to vegetation was worse than that of employing wind power plants, suggesting that the mine ecological environment restoration should be strengthened by the local government. This study is expected to be useful for ecological conservation and watershed management in the headwaters of the Jialing river.