非线性植被—侵蚀动力学模型初探  

A preliminary study on nonlinear vegetation-erosion dynamics model.

作　　者：王费新[1] 王兆印[1] 

机构地区：[1]清华大学水沙科学国家重点实验室

出　　处：《北京林业大学学报》2007年第6期123-128,共6页Journal of Beijing Forestry University

基　　金：国家自然科学基金项目(40371010;50221903-3);国家自然科学基金委员会与香港研究资助局联合科研资助基金项目(50318003)

摘　　要：植被-侵蚀动力学是一门研究流域植被与侵蚀在人类活动影响下演变规律的边缘学科.现有植被-侵蚀动力学模型是基于指数增长模型建立的,在多数时段具有较高精度,但在高植被覆盖度(V)、低侵蚀率(E),以及低V高E等特殊时段精度略差.为提高模型模拟精度并扩大其适用范围,该文提出了一种基于Logistic模型的非线性模型,并将两种模型应用于北京西山地区、宁夏西吉黄家二岔、陕西长武王东沟以及广东惠州上杨试验站等小流域植被及侵蚀演变过程的模拟.结果表明,非线性模型在一般时段的模拟精度与线性模型相当,而在特殊时段,前者的精度明显高于后者.但是非线性模型求解复杂,引入的两个新参数需深入研究确定.同时,由非线性模型推出的植被-侵蚀状态图形式复杂且不完全符合实际情况,不如由线性模型得到的植被-侵蚀状态图简单实用.非线性模型还有待于进一步地修正和完善.Vegetation-erosion dynamics is a new interdisciplinary science studying the laws of evolution of watershed vegetation and erosion under the action of various ecological stresses.Based on an exponential growth model,the current linear model of vegetation-erosion dynamics can be used to simulate the vegetation growth and erosion process.However,in a period of extreme conditions,such as a period with severe soil erosion and poor vegetation cover or with high vegetation cover and low erosion,the results calculated by the model can＇t agree completely with the measured data.To solve this problem,a nonlinear model of vegetation-erosion dynamics based on a logistic growth model was developed in this paper.Both the linear model and the nonlinear one were applied to Xishan Area in Beijing,Huangjiaercha Watershed in Xiji County of Ningxia Hui Autonomous Region,Wangdonggou Watershed in Changwu of Shaanxi Province,and Shangyang Field Station in Huizhou,Guangdong Province,for the simulation of vegetation and erosion evolution.The results show that the two models can both accurately simulate the vegetation and erosion evolution in most periods,but in the two kinds of periods with extreme conditions previously mentioned,the simulation accuracy of the nonlinear model is much higher than that of the linear one.Nevertheless,it＇s much more complicated to get the solution of the nonlinear model to compare with the linear one.The nonlinear model involves two new parameters to be determined.Moreover,in comparison with the linear one,the vegetation-erosion chart derived from the nonlinear model is less realistic and is too complicated for application.More researches are needed to modify and improve the nonlinear model.

关 键 词：植被发育 土壤侵蚀 增长模型 动力学方程 

分 类 号：O175.14[理学—数学] S714.7[理学—基础数学]