摘要
20世纪初期CLEMENTS的演替学说被引入草原科学,标志着草原科学理论的一大进步。在此后相当长的一个时期,以演替学说为代表的平衡生态学理论对全世界草原科学研究和草原资源管理模式产生了深远的影响。然而,20世纪70和80年代以来,平衡生态学和稳态管理模式日益受到批评。一方面,在草原生态系统的研究中发现植被动态表现出非线性特征,而这与传统演替理论和稳态管理观点不一致。另一方面,在世界其他地区开展的研究发现,在美国建立起来的草原科学理论和管理模式,在亚洲、非洲等环境随机干扰比较频繁的生态系统并不适用,因而呼吁研究新的框架模型,以便更准确地解释实际的草原植被动态,更有效地为草原管理提供科技支撑。在此背景下,非平衡生态学应运而生。特别是在东非草原生态系统的研究,提出了生态系统是非平衡的但又是可持续的(持续非平衡模型)的观点。进一步的研究揭示了干(冷)季关键资源相对比例对家畜数量和草原植被的潜在影响。20世纪80年代提出的状态与过渡模型是一个具有重要意义的替代性概念框架,20世纪90年代在美国被应用于草原管理实践,取代了盛行多年的草原基况评价。而非平衡理论则逐渐被后出现的恢复力理论所替代,因为研究发现过去认为的"非平衡态",被解释为"多平衡态"似乎更为合理。生态恢复力在涉及多稳态生态系统管理的领域得到了广泛应用,特别是复杂的社会生态系统的适应性管理。草原生态学理论的进步,也伴随着草原资源管理模式的平行发展,其中一个极为显著的特征是人类的角色从自然资源的利用者转变成了自然资源的管理者。20世纪草原管理的主要模式被概括为稳态管理,其目标是获得牧草和家畜产品的最大可持续产量。恢复力理论代表了当代生态学最新、最重要的进展,其应用进一步扩展到社会系统与生态系统的耦合——社会生态系统,并促进了适应性管理等概念和方法的发展。目前,上述几种管理模式在草原生态学领域都有不同程度的应用。随着时间的推移,草原生态学理论和管理模式必将得到进一步的发展和整合,从而形成更完善的框架模型,能更加有效地应用于兼具复杂性、适应性和社会性的草原生态系统。
The introduction of Clementsian succession theory in early twentieth century represented a substantial advance in rangeland ecology. Succession theory as a central concept of equilibrium ecology had profound influence on development of rangeland science and natural resource management models. However, equilibrium ecology and the steady-state management model received severe criticism in 1970 s and 1980 s. On one hand, nonlinear vegetation dynamics was recognized in rangeland ecosystem research, which is inconsistent with the interpretation of the traditional succession and steady-state management. Onthe other hand, research in other parts of the world indicated that the rangeland concepts and range models developed in the United States did not well apply to the ecosystems in Africa and Asia where the prevailing environments are characterized by frequent disturbances and alternative conceptual frameworks are called for to provide more realistic, accurate interpretations of range vegetation dynamics and scientific support to natural resource management. In this context, equilibrium ecology emerged in response to the dissatisfaction of the prevailing ecological theory. In particular, an ecosystem-level research in east Africa presents a view of pastoral ecosystems that are nonequilibrial but persistent(persistent nonequilibrium model), and further research resulted the recognition of the importance of relative proportion of key resource in the dry/cold season as the determinant of animal numbers and their potential impacts on vegetation. The state and transition models which emerged in 1980 s represented an important alternative conceptual framework and were applied in 1990 s to rangeland assessment as a replacement of range condition in USA. Resilience is currently replacing nonequilibrium as the dominant ecological concept because ecosystems that were previously considered nonequilibrium is now more appropriately interpreted as multiple equilibria in many cases. The advances in rangeland ecological theory have been accompanied by parallel progression of rangeland management model, notably a transformation of the role of human from resource users to resource stewards. The rangeland models in twentieth century were generalized as steady-state management with the overall goal of maximizing sustainable production of forage and livestock. The application of resilience as the most recent and important ecological advance has been extended to coupled social-ecological systems, leading to the development of the concept and procedures of adaptive management. Currently the above described models are in application to a greater or less extent and synthesis of different models for rangeland assessment and management will help develop improved framework for complex, adaptive socialecological systems.