黄河上游植被覆盖度空间分布特征及其影响因素

采用2000—2015年MODIS1M NDVI数据计算黄河上游年最大植被覆盖度 (FVC)，了解空间分布状况及变化特征；同时，采用了一种基于统计学原理的地理探测器模型，考虑非气候类环境因素、气候类环境因素和人类活动因素，使用相应的代理变量对黄河上游FVC空间分布的影响因素做定量研究。研究表明：① 黄河上游FVC总体上以改善为主，空间分布特征变化不大；② 单因子方面，降水量(q值0.669)是该地区FVC空间分布的主要影响因素，其他因子的影响作用存在区域差异；③ 降水分别和土壤类型、土地利用方式的交互作用(q值0.777、0.775)对研究区FVC空间分布起主导作用，土壤类型和土地利用的影响作用在一定高程、降水条件下才得以体现；④ 总体上，气候类环境因素>非气候类环境因素>人类活动因素，人类活动在与降水等环境因子的共同作用能够更充分地解释FVC空间分布；⑤ 对研究区的生态恢复应重点放在降水的充分利用和土地利用方式改进等方面。

Spatial Distribution of Vegetation Coverage and Its Affecting Factors in the Upper Reaches of the Yellow River

The ecosystem in the upper reaches of the Yellow River is fragile, and it is affected by the unique ecological environment and relatively simple vegetation types. The distribution of fractional vegetation cover (FVC) and its driving factors provide a reference for local vegetation protection. In this paper, the monthly data of MODIS1M NDVI (2000-2015) were used to calculate the maximum FVC in the upper reaches of the Yellow River and analyze its distribution and characteristics. Moreover, the corresponding proxy variables were used to quantitatively study the affecting factors of FVC by using the geographical detector (Geodetector) model based on the statistics theory and considering the topographical, geological and climatic factors as well as human activities. The study showed that: ① The FVC in the upper reaches of the Yellow River was improved. The spatial distribution of FVC was stable even if there was a slight fluctuation; ② The distribution of FVC was mainly affected by annual precipitation. There were some regional differences in the effects of other factors, for example, the distribution of FVC in the southwest of the study area was subject to the joint effect of topography and pressure, the effects of topographic factors in the central and northeast regions were relatively low, and the FVC was mainly subject to precipitation, humidity, land use types, soil types and underlying surface; ③ The interaction between the annual precipitation and the soil types and land use types was dominant to affect the spatial distribution of FVC; ④ Holistically, the factors affecting the spatial distribution of FVC were in an order of climatic environment factors > non-climatic environmental factors > human activities. The interaction of human activities with environmental factors (such as precipitation) could be used to fully explain the spatial distribution of FVC; ⑤ In the ecological restoration in this area, the full utilization of precipitation and the improvement of land use ways should be focused on.