草原生态食物链对人类活动干扰的响应

运用非线性动力学方法，建立在人类活动干扰下，草原生态食物链上肉食种群一草食种群一草地资源三者的微分动力系统模型。并对平衡态进行数值模拟，研究草原生态食物链对人类活动的干扰随时间变化作出的响应．研究结果表明：①系统达到平衡时。草地资源密度与草食对肉食种群的转化率成正比，与自身退化率、草食种群的消费率成反比，表明三者间的密度调节与制约机制；②草地资源的退化率m3大于生长率ra时，草地资源密度先迅速下降继而迅速上升；草食种群与肉食种群均逐步灭绝，表明人类应充分保护草地资源，更要限制牲畜放牧的强度，选择合理的捕杀强度是维持食物链生态平衡和保证生产效益的关键．在此基础上，文章对协调人类活动与草原生态环境的健康发展提出了建议．

The Respond of Ecological Food Chain to the Disturbance of Human Activity in Grassland

Nonlinear dynamic means is utilized in this paper and a nonlinear dynamic model of the ecological food chain is established to describe the relationship among the predator, herbivore and meadow resource under the disturbance of human activity, which are the three most important elements lying in the ecological food chain. On the base of such a model, the steady state is numerical simulated and the respond of food chain to the disturbance of human activity along with the time is analyzed through simulation. The results show that: (1) When the system comes to balance, the density of meadow resource has a positive relationship with transition rate between herbivore and predator and a negative relation with its own degradation rate, also the consumption rate of herbivore, which indicates the mechanism of density accommodation and restriction among the three elements; (2) When the degradation rate of meadow resource is bigger than its growth rate, the density of meadow resource falls quickly and then rises rapidly, while herbivore and predator becomes dying out step by step and predator ones will die out in just forty years which indicate human beings must not only protect meadow resource, but also control the intention of depasture dumb things, and the rational intention is a key factor of guarantee of ecological balances and human benefits. On the base of such numerical simulation, some suggestions are put forward to harmonize the human activity and healthy development of grassland environment.