基于降水条件的城镇化与植被覆盖协调发展研究

为探讨城镇化发展与植被覆盖状况的协调发展关系,本文以黄河中上游的144个县域单元为研究对象,基于2000、2005、2010及2015年4期的县域经济发展数据及MODIS-NDVI数据,通过门槛回归模型,以影响研究区域植被覆盖最主要的降水因素作为门槛变量,具体分析不同降水条件下城镇化发展对植被覆盖的影响,并提出以保护植被覆盖为基础的差异化城镇化发展策略。结果表明：①随着城镇化的推进,植被覆盖会进一步遭到破坏,但降水因素在城镇化影响植被覆盖的过程中可发挥显著的正向调节作用,从而促进城镇化与植被覆盖的协调发展;②实现城镇化与植被覆盖的协调发展,不仅取决于自身的降水条件,还依赖于当地的生态工程建设及产业结构优化升级等多种因素。其中,退耕还林(草)政策的实施可加速植被覆盖的修复进程,提高区域环境的生态承载力,有效缓解城镇化发展带给植被覆盖的负面影响;③第二产业在经济发展中的比重增加会给植被覆盖带来严重威胁,阻碍城镇化与植被覆盖的协调发展,尤其是在年均降水量较少且生态脆弱的地区。

Coordinating the development of urbanization and vegetation coverage based on precipitation

In order to explore the coordinated development of urbanization and vegetation coverage, this study used the economic development and MODIS-NDVI data of 144 counties in the middle and upper reaches of the Yellow River Basin for 2000, 2005, 2010, and 2015 and the threshold regression model to analyze the influence of urbanization on vegetation coverage under different precipitation conditions. Precipitation was taken as the threshold variable that exerts the most significant impact on vegetation coverage. The results show that: (1) Along with the advancement of urbanization, vegetation covers are damaged, but precipitation during the process can play an important role in adjusting the relationship positively and promote the joint development of urbanization and the vegetation coverage. (2) The coordinated development of urbanization and vegetation coverage depends not only on precipitation, but also on local ecological construction, optimization and upgrading of industrial structure, and so on. The implementation of the Sloping Land Conversion Program on the Loess Plateau can accelerate the restoration of the vegetation cover, improve the ecological carrying capacity of the regional environment, and effectively alleviate the negative impact of urbanization development on vegetation coverage. (3) The increase of the proportion of the secondary industry in economic development poses a serious threat to the vegetation, which may halt the coordinated development of urbanization and vegetation coverage, especially in areas with low annual rainfall.