西南山区人口空间重组及其对植被的影响——以河流沿线为例

随着城市化的快速推进,山区人口迁出及空间重组成为影响中国山区人地关系的重要因素,这可能对山区植被恢复和生态改善产生巨大影响。基于人口空间数据、河流分布数据和MODIS数据,本文分析了河流沿线人口空间重组情况,以生长季EVI值为表征植被绿度的指标,采用基于像元的趋势分析方法和基于样本的相关分析模型,对2000—2010年间中国西南山区不同级别河流沿线的人口空间变化和植被变化作了系统性分析,并定量研究了人口空间重组与植被变化之间的关系。结果表明:(1)三级及以上河流出现人口往河流沿线聚集的趋势,人口在河流的影响区聚集程度大于对比区。其中,一级和二级河流沿线影响区人口密度增加量比对比区分别高75.9%和42.1%。(2)三级及以上各河流沿线影响区和对比区EVI均呈现出增加的趋势,且影响区增加趋势低于对比区。(3)植被EVI变化趋势与人口密度变化呈负相关关系,河流沿线人口密度增加不利于植被的恢复;河流级别越高,植被EVI变化趋势与人口密度变化的相关性越强。

Spatial redistribution of populations in mountainous areas and its impact on vegetation change in southwest China: A riverside case study

With the rapid advancement of urbanization, population redistribution has become one of the factors affecting the human-land relationship and the restoration of vegetation and ecological improvement in mountainous areas of China. Using population distribution data, river system data, and MODIS data, this paper systematically analyzed the spatial changes in population and vegetation greenness along the different grades of the river in the mountainous areas in southwest China from 2000 to 2010. Then, the relationship between population spatial redistribution and vegetation change was quantitatively analyzed. The results showed that:(1) Population density along the rivers of Grade 3 and above had a higher increase rate in the affected areas compared with the comparison areas. The increase rates of population density in the affected areas were 75.9% and 42.1% higher than those of the comparison areas, along the primary and secondary rivers, respectively. (2) The EVI (Enhanced Vegetation Index) increased in both the affected and the comparison areas along the rivers of Grade 3 and above. The increase of EVI in the comparison areas were higher than those in the affected areas. (3) The trend of EVI variation had a negative relationship with the changes in population density, indicating that the increase in population density along the rivers influenced the improvement of the vegetation cover. For the rivers with higher grade, the correlation between population density change and the trend in EVI variation was stronger.