基于GRID的坡耕地退耕压力模型研究

坡耕地退耕还林还草作为保护生态环境的重要措施,已于2000年在长江上游及黄河中上游等地区进行大面积试点。然而,坡耕地退耕还林还草也引发一系列局域性和阶段性的复杂问题,如粮食安全保障、生态移民安置等。这些问题产生的重要根源是坡耕地空间分布差异导致的人口压力状况的空间差异。文章设计了4个基于GRID的坡耕地退耕人口压力指数模型,并以三峡库区的奉节县为例进行了模拟。

A Study of population stress simulation in slope cropland de-farming based on grid

Huge amount of steep slope land reclamation is a key reason for soil erosion and and eco environmental degradation in China. As a fundamental countermeasure of ecological rehabilitation, the experiment of returning farmland to woodland and grassland was conducted in large areas of the upper reaches of Yangtze River and the middle and upper reaches of Yellow River in the year 2000. However, a series of problems were also resulted from the process of de farming, such as food safety, allocation of ecological emigration. An important springhead of these problems is the spatial disparity of population stress caused by spatial disparity of slope farmland distribution. The more concentrated the slope farmland is, the more complex the problem of population stress is. Four population stress index models in de farming process based on GRID is designed in this research: (1) the fundamental de farming stress model based on the ratio of slope farmland to total farmland:p i= u iv i×100%.p i stands for population stress index;u i stands for the percentage of slope farmland to the neighborhood area; v i stands for percentage of farmland to the neighborhood area. (2) the modified model concerning the disparity farmland quality. (3) the modified model concerning the spatial disparity of population distribution. (4) the modified model concerning the development of economic forest on de farmed slope farmlands. Finally, taking Fengjie County for example, simulations are conducted using these models, and available results of de farming stress indexes are obtained in different locations under various conditions.