Li Wei, Li Xiubin, Tan Minghong, Wang Yahui
Key Laboratory of Land Surface Pattern and Simulation Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing China.
College of Resources and Environment University of Chinese Academy of Sciences Beijing China.
Ecol Evol. 2017 Sep 25;7(21):9041-9053. doi: 10.1002/ece3.3424. eCollection 2017 Nov.
Mountainous areas in China account for two-thirds of the total land area. Due to rapid urbanization, rural population emigration in China's mountainous areas is very significant. This raises the question to which degree such population emigration influences the vegetation greenness in these areas. In this study, 9,753 sample areas (each sample measured about 64 square kilometers) were randomly selected, and the influences of population emigration (population pressure change) on vegetation greenness during 2000-2010 were quantitatively expressed by the multivariate linear regression (MLR) model, using census data under the condition of controlling the natural elements such as climatic and landform factors. The results indicate that the vegetation index in the past 10 years has presented an increasing overall trend, albeit with local decrease in some regions. The combined area of the regions with improved vegetation accounted for 81.7% of the total mountainous areas in China. From 2000 to 2010, the rural population significantly decreased, with most significant decreases in the northern and central areas (17.2% and 16.8%, respectively). In China's mountainous areas and in most of the subregions, population emigration has significant impacts on vegetation change. In different subregions, population decrease differently influenced vegetation greenness, and the marginal effect of population decrease on vegetation change presented obvious differences from north to south. In the southwest, on the premise of controlling other factors, a population decrease by one unit could increase the slope of vegetation change by 16.4%; in contrast, in the southeastern, northern, northeastern, and central area, the proportion was about 15.5%, 10.6%, 9.7%, and 7.5%, respectively, for improving the trend of NDVI variation.
中国山区面积占国土总面积的三分之二。由于快速城市化，中国山区农村人口外流现象十分显著。这就引发了一个问题，即这种人口外流在多大程度上影响了这些地区的植被绿化。本研究随机选取了9753个样本区域（每个样本面积约64平方公里），在控制气候和地形等自然因素的条件下，利用人口普查数据，通过多元线性回归（MLR）模型定量表达了2000 - 2010年期间人口外流（人口压力变化）对植被绿化的影响。结果表明，过去10年植被指数总体呈上升趋势，尽管部分地区局部有所下降。植被改善区域的面积占中国山区总面积的81.7%。2000年至2010年，农村人口显著减少，其中北部和中部地区减少最为显著（分别减少17.2%和16.8%）。在中国山区及大部分子区域，人口外流对植被变化有显著影响。在不同子区域，人口减少对植被绿化的影响不同，人口减少对植被变化的边际效应从北到南呈现出明显差异。在西南地区，在控制其他因素的前提下，人口减少一个单位可使植被变化斜率增加16.4%；相比之下，在东南部、北部、东北部和中部地区，改善NDVI变化趋势的比例分别约为15.5%、10.6%、9.7%和7.5%。
