The Adaptive Cycle Mechanim And Versue Arid Resilience Of Rural Social-Ecological System In The Loess Plateau

In the Loess Plateau of China, the ecological problems are closely inter-linked with the development of local socio-economic system. How to analyze ecological processes coupled with socio-economic process has a great significance to the region's sustainable development. This paper explored the evaluative mechanism of adaptive cycle of rural social-ecological system (SESs) in Loess Plateau by using social-ecological system theoretical framework based on a questionnaire survey of households and historical statistics, which was carried out on the three cases of Yuzhong County of Gansu Province, Zhonglianchuan village of Yuzhong County and Wangdong village of Changwu country, Shangxi Province, respecticely. The resilience of Yuzhong County to drought was also semi-quantatively measured for the last 15 yeas through system modeling and analytical hierarchy process. The main results are as follows:(1) Since 1949 three SESs have experienced a complete adaptive cycle and are all in the exploitation phase of the second adaptive cycle. The first adaptive cycle of Yuzhong County SESs and Zhonglianchuan village SESs lasted from 1949 to 1982, while that in Wangdong village SESs went through during 1949-1980. Two SESs on the village scale fell into a poverty trap while the SESs of Yuzhong county rapidly entered into renewed phase of reorganization after collapse release in 1961. In the second adaptive cycle, three SESs experienced two exploration phases, and the beginning time of the second exploitation phases could be identified for each SESs: Yuzhong County in 2000, Zhonglianchuan in 1997 and Wangdong Village in 1987.(2) Climate change, institution response, technological innovation and adjustment of eating habits are the main driving forces that control the adaptive coevolution of SESs in the Loess Plateau. Climate change and adjustment of eating habits affect the SESs slowly, which destroy key variables of the system mainly through their long-term accumulative effects. Policy responses, institution response and technological innovation have a rapid impact on the sys and promote the system's evolution forward. The reform of land policy is the leading force to SESs which ended the first cycle and put SESs into the second cycle. The external scientific and technological strength made a sudden intervention into SESs, which pulled the system into the second exploration phase and maintained up to the present.(3) Over the past 15 years, the resilience of Yuzhong County's SES to drought tended to increase slightly and the highest value was found in 1995 with the lowest in 2001.(4) The resilience of Yuzhong County's SES to drought mainly depends on the external drought stress and internal water sensitivity. The drought stress could be represented by drought index, which varied greatly for each year. Whereas the internal water sensitivity of SES was mainly affected by community population, learning ability and labor per capita for social subsystem, net income, cropland area per capita and food production for economic sub-system and, crop productivity per area, the proportion of irrigated area and of terracing land.