Semi-arid Social - Ecological System Dynamic Evolution Mechanism

Social-ecological systems refer to the linked systems of people and nature, which are dynamic, non-equilibrium, hierarchical and with multi-stable state mechanism. As one of the key attributes of social-ecological systems, resilience can be defined as the capacity of a system to absorb disturbance and reorganize while undergoing change so as to still retain essentially the same function, structure, identity, and feedbacks. Since social-ecological systems suffer the constant external perturbations and shocks, its future is highly uncertain. Yet many current studies mainly focus on description and qualitative analysis, which cannot offer effective methods to evaluate the future of the social-ecological systems and to quantify resilience of the systems. So, it has been an imperative trend to deepen the dynamic evolution mechanism study of the social-ecological systems.Based on the theory of social-ecological systems and its related theories including resilience and adaptive cycle, this paper first introduced scenario analysis to the social-ecological systems study, reviewed its concept, processes and several successful cases study, and summarized the development of methodology of scenario analysis. Secondly, Based on the water sensitivity indicators selected from ecological subsystem, economic subsystem and social subsystem, the resilience of social-ecological system to drought in northern highlands area of Yuzhong County of Gansu Province during 1982-2006 were calculated by integrating statistics approaches. Thirdly, Based on the scenario interviews with multi-stakeholders including farmer, local governmental manager and academic experts, the scenario logical framework was identified by analyzing the driving forces to the system, the key factors and key events were selected to represent for the system's future, and the future scenarios and their probabilities was constructed and calculated by using the cross-impact analysis. Then, three scenarios were released and described. In the framework of scenarios, we next sought for the next phase of adaptive cycle which the social-ecological system of northern highlands area of Yuzhong County will experience. Finally, based on the framework of scenarios, we offered some practical instructions and decision suggestions to this area for solving the problems caused by drought.Conclusion of this paper can be summarized as follows: 1. The results of resilience value indicated that the social-ecological system of northern highlands area of Yuzhong County has experienced a complete adaptive cycle in 1982-2006. And in this adaptive cycle process, drought, policy response and technological innovation are the main driving forces.2. The scenario analysis showed drought and decision-making are key driving forces of the social-ecological systems of northern highlands area of Yuzhong County, and the two key driving forces identified the scenario logical framework. The cross-impact analysis resulted showed that the three scenarios of the social-ecological system in 2020 with the maximum probabilities are congruent with the scenario logical framework. Because of their different location in the scenario logical framework, the three scenarios have different meanings.3. In 2020, the scenario "S₁" means the social-ecological system of northern highlands area of Yuzhong County will experience Conservation phase of adaptive cycle. The scenario "S₂"and "S₃" means the social-ecological system will still experience Reorganization phase of adaptive cycle.