平衡与非平衡生态学在锡林河流域典型草原放牧系统中的应用

为认识放牧系统的复杂性和稳定性 ,产生了放牧系统的平衡生态学和非平衡生态学原理。放牧系统的平衡生态学原理假定 :一旦干扰在系统中发生 ,系统将偏离平衡态 ;而当干扰解除后 ,系统将自动返回原来的状态或在新的领域实现平衡。在对内蒙古锡林河流域典型草原放牧系统动态的研究中 ,来自平衡生态学的 Clem ents- Duksterhuis演替理论提供了一个基本的研究框架。尽管已经证实对退化不太严重的典型草原放牧系统 ,平衡生态学原理是适用的 ,但是对于这一地区严重退化的放牧系统的动态 ,它显然并不能给予合理的解释。事实上许多放牧系统动态遵循非平衡生态学原理。在非平衡放牧系统中 ,稳定的状态是不会实现的 ,因为在这样的系统中 ,非生物变量对于植被的动态似乎起着决定性的影响 ,从而也决定着草食动物的种群动态。状态与过渡模型基于非平衡生态学原理 ,它能够解释过度放牧下典型草原生态系统的崩溃或灌丛化 ,因此它适于该地区严重退化的典型草原放牧系统的动态。鉴于内蒙古锡林河流域典型草原放牧系统普遍严重退化的现实 ,未来该地退化放牧系统的研究应更多地应用非平衡生态学原理 ,并且严重退化的草原生态系统的恢复试验 ,特别是灌丛化草原的重建也应置于它的指导之下

Application of the equilibrium and non-equilibrium ecology to the dynamics of the steppe grazing system in Xilin River Basin, Inner Mongolia

To understand the complexity and stability in grazing systems, the equilibrium and non-equilibrium ecology theory have been developed. The equilibrium ecology theory postulates that, once disturbance has occurred in a system, the system state either returns to its former equilibrium or equilibrates within a new domain of attraction. Clements-Duksterhuis succession theory, from the equilibrium ecology, has provided one basic paradigm for the research on the dynamics of the steppe grazing systems in Xinlin River Basin, Inner Mongolia. Although this theory has been verified to fit for the dynamics of no heavily degraded steppe grazing systems, it could not give the reasonable explanation for the dynamics of heavily degraded steppe grazing systems in this region. Many grazing systems are substantiated to follow the non-equilibrium dynamics. The non-equilibrium ecology theory presumes that a steady state is never achieved, in these systems it would seem that abiotic variables have an overriding influence on vegetation dynamics and hence also on herbivore populations. The State and Transition Models, based on the non-equilibrium ecology theory, could well document the dynamics of the heavily degraded steppe grazing systems, since it could explain the breakdown and the thicketization of steppe ecosystems under overgrazing. Considering the widespread occurrence of the heavily degraded steppe, researches in the future should be combined more with the non-equilibrium ecology in Xinlin River Basin, Inner Mongolia. In addition, the restoration of heavily degraded grazing system, especially the rehabilitation of thicketization steppe, should be guided by this theory in this region.