黄土高原植被覆盖与水热时空通径分析

探究黄土高原地区气象因子对植被覆盖的影响作用以丰富生态修复理论。基于黄土高原2001—2017年归一化植被指数(Normalized Difference Vegetation Index, NDVI)与气象数据，采用通径分析方法分别从时间和空间尺度上，分析黄土高原气温和降水对植被覆盖变化的直接及间接影响作用，为该地区生态建设提供科学依据。结果如下：黄土高原地区年际间植被明显波动增长，降水变化大体上与植被变化相似；降水整体较气温对植被覆盖变化的作用大。黄土高原植被与水热空间关系的最优分析尺度为80km,在80km空间尺度上，植被与气温有最大相关性，植被、降水由东南到西北递减，而气温分布规律不显著；降水整体呈现促进作用，气温的抑制作用较强，且空间差异明显。在时间与空间尺度上，植被主要受水热促进尤其是降水促进影响，且降水对植被生长的直接作用远大于通过气温的间接作用；不论生态区还是植被类型，气候因子作用均以促进类型为主，但存在明显差异。水热作用在时空尺度上具有明显空间差异性，不同地区影响植被变化的主控因子不同。

Path analysis between vegetation coverage and climate factors in the Loess Plateau

Exploring the influence of climate factors on vegetation coverage in the Loess Plateau can enrich the ecological restoration theory. In order to provide a scientific basis for the ecological construction of the Loess Plateau, the direct and indirect effects of temperature and precipitation on vegetation were analyzed by using the path analysis, based on MODIS NDVI and corresponding meteorological data from 2001 to 2017. The findings are as follows the annual fluctuation growth of vegetation in the Loess Plateau were obvious, and the precipitation variation was like that of vegetation. Precipitation played a more important role than temperature overall. The maximum correlation between vegetation and temperature was found at the spatial scale of 80 km. At the spatial scale, vegetation and precipitation decreased from southeast to northwest, but the distribution of temperature was not significant. Precipitation presented a promoting effect on the whole while temperature mainly showed an inhibiting effect, and there was obviously spatial difference. On the temporal and spatial scale, vegetation was mainly affected by the promoting effect of climate factors, especially precipitation. The direct promoting effect of precipitation on vegetation is much greater than the indirect effect of temperature. Regardless of ecological areas or vegetation types on the Loess Plateau, the main effect of climate factors is promoting type, but there are obvious differences. On the spatial and temporal scales, the effects of meteorological factors obviously show the spatial difference. The main control factors affecting the vegetation are different in different regions, which has a theoretical guiding significance for the ecological management of the Loess Plateau and related problems in the process of management.