基于SD模型的中国2010―2050年土地利用变化情景模拟

Simulating Multiple Land Use Scenarios in China during 2010-2050 Based on System Dynamic Model

通过将中国划分为4个生态区,在综合考虑社会经济和自然因素的前提下,利用系统动力学的原理和方法,选取对土地利用变化影响最大的驱动因素,分区构建中国土地利用变化系统动力学模型并模拟4种发展情景下2050年中国土地利用变化情况。结果表明:在不同情景设定下,土地利用变化差异较大,其中平稳发展情景较理想,生态用地保持良好,城市扩张较为合理;建设用地发展给予的压力以及气候条件的不断恶化,使得4种情景下水域面积在2045年前都呈现减少趋势,需要管理者严控城市扩张,提早规划布局以应对相应挑战;气温和降水对4个生态区的林地和草地影响程度不同,水域面积主要受到降水影响,而技术进步带来的粮食单产提高是影响耕地面积变化的重要因素。

China is going through a rapid urbanization process, which will have significant influences on the land use pattern in the nationwide scale. In this context, it is very important for getting more information about the overall trend of land use change in the coming decades. To help develop better land management policies and improve the land resource allocation, this paper provides a system dynamic model which is able to project future demands of multiple land use types under the influences of various climate change and socioeconomic factors （e.g. population, gross domestic product, investment） for large scale region in different scenarios. The developed SD model consists of four sub-modules： the population sub-module, the economy sub-module, the climate sub-module and the productivity sub-module. Meanwhile, four regions （the northeast humid and semi-humid region, the northern arid and semi-arid region, the southern humid region and the Tibet Plateau region） were designated based on China＇s provincial boundary according to the regional natural ecological conditions and socio-economic development. The model is applied in China's Mainland to simulate future land use demands under four different scenarios from 2015 to 2050 （the fast development scenario, the baseline development scenario, the harmonious development scenario, the slow development scenario）. These scenarios are developed based on future temperature and precipitation data provided by the IPCC assessment reports. The simulation results show that our newly developed SD model is able to effectively simulate long term land use change under different land use scenarios. The analysis results demonstrate that the demand for each land use type, especially the construction land and cultivated land, will vary greatly in different land use scenarios. The demand for construction land will grow in four scenarios, especially in the fast development scenario. The future demand for cultivated land will be relatively low in the baseline development scenario and the slow development scenario. In addition, the harmonious development scenario is the healthiest, which successfully keeps more ecological land than other scenarios. Besides, because of the climate change and construction land increment, the amount of water area tends to decrease in all four scenarios from 2015 to 2045. Therefore, managers should strictly control the city expansion to meet the challenges from the reduction of the water stores. The impacts of temperature and precipitation on forestland and grassland are different in the four regions. In southern humid region, areas of forest land and grassland are mainly affected by temperature. In northeast humid and semi-humid region, temperature is also the key factor for area change of grassland. In northern arid and semi-arid region, most land use types are mainly affected by precipitation while the effects of temperature on forestland and grassland cannot be ignored. In the Tibet Plateau region, forestland and grassland areas are mainly affected by precipitation. The cultivated land areas in four scenarios are more than 2 billion mu. It shows an increase from 2010 to 2050 in the fast development scenario but decreases in the other three scenarios. Especially, in the slow development scenario, the cultivated land area in 2050 will be 12.9% lower than that in 2010. This indicates that if future climate is deteriorating, it will be necessary for managers to take measures to protect cultivated land from degradation. Moreover our analysis results also indicate that the improvement of technology is also an important factor for affecting the amount of cultivated land.