多主体系统理论在鄱阳湖区土地利用时空变化过程研究中的应用

本研究选取鄱阳湖区为典型区,在多主体系统理论(multi-agent system theory)的基础上建立了一个包含两个子模块的土地利用变化模拟系统,其中城市土地扩张子模块采用有限扩散聚合模型模拟城市主体的定居过程,农村土地利用变化子模块则通过模拟主体之间以及主体与环境之间的相互作用来研究土地利用变化的过程.鉴于土地利用变化的复杂性,农村土地利用变化子模块包括多种类型的主体和环境层.农户主体作为土地利用决策的直接制定者,是模块中最重要的主体,其决策行为主要有两种: 耕地扩张决策和耕地位置选择决策.在整个系统中,国家政策对土地利用的影响由一个政府主体来反映.通过对模型的校准,发现本研究建立的土地利用变化模拟系统的模拟结果与实际观测数据相符较好,模拟精度符合要求,其中城市扩张子模块的模拟效果最佳,模拟出的城市发展规模和方向都与实际情况较为一致.同时,模拟结果也表明国家政策对鄱阳湖区土地利用变化的影响十分显著.

Application of the Multi-Agent System Theory to Land Use/Land Cover Change in the Poyang Lake Area

Due to rapid economic growth, land use types have changed dramatically in the Poyang Lake area. Here, we developed a land use/land cover simulating model based on a multi-agent system to estimate the driving factors of land use change. We divided household agents into six categories based on income and the rate of migrant workers, among which different decision rules are followed. The model focuses on studying the relationship among different kinds of agents, and the interactions between agents and the environment. It was implemented in the Poyang Lake area to simulate land use change from 1985-2005. The results show our model can successfully reproduce land use change in the Poyang Lake area, and simulation accuracy for 2000 and 2005 was 76.2% and 69% respectively. The results indicate that the simulated direction and quantity of urban expansion was consistent with actual situations in 2000, but urban growth is not a uniform process. For example, policies can speed up the development of urbanization but our results, however, do not show the impacts of policies. The growth of urban populations in the Poyang Lake district is not only the result of internal factors but also includes developments from across China after 2000, so the area of urban land was obviously underestimated in 2005. The trends in cropland, water area, grassland and forest were consistent with observed land use data. Overall, our model shows that land use change in the region has followed a close relationship with governmental policy.