Oasis Stability And Oasis Stability Evaluation Indicator System

As special landscapes in arid-zone, oases are the main places for people's living and production. The oasis stability is of vital importance to the sustainable development of social-economy. The essence of oasis-stability is to keep the circulation of energy, matter, men and information of the oasis ecosystem in a good circle state. The oasis stability is essentially not only determined by its internal and external structures, function and ecological process, but also affected by climate-change and the distribution of water and other resources. Many factors can cause the degradation, shrinkage and vanishment of the oases, such as the rapid changes of some natural factors, radical changes of some social factors, or the interaction between natural and social factors.Taking Fukang Oasis as an example and focusing on the vegetation community in desert-oasis ecotone and the interaction between desert and oasis, we investigate some basic laws of desert-oasis ecosystem on the community scale and landscape scale. On the community scale, we study the community stability in the ecotone, photosynthetic properties of two species in ecotone and gas exchange characteristics of four desert shrubs. On the landscape scale, we study the oasis stability under the influence of oasis effect causing by the interaction between oasis and surrounding desert in theSangonghe (river) Basin. We initially deal with the internal and external factors affecting the stability of Fukang Oasis. Finally, we examine the oasis ecosystem stability evaluation indicator system, and evaluate the stabilities of 10 oases in Xinjiang. Following results are obtained:1. Net photosynthesis rate of Reaumuria soongorica is slight higher than Haloxylon ammodendron, but water use efficiency of Haloxylon ammodendron is evidently higher than Reaumuria soongorica. It suggests that Haloxylon ammodendron has strong bearing ability to drought in natural habitat.2. Besides plant physiological traits, stomatal conductance is very sensitive to environmental elements such as photosynthesis active radiation (PAR), relative humility (RH), air temperature (Ta).3. The plant community stability differs from here and there in the desert-oasis ecotone, although under the same climate. The plant community stability is influenced by species competition, environmental pressure and human activities. There are big differences in stability between different communities, even though they have same constructive species.4. In Sangonghe Basin of Fukang, the general trend of external oasis stability has increased gradually during the past 35 years. Especially since 1990s, the stability has raised rapidly.5. At present, for Fukang Oasis, the desertification from its northern boundary just potentially threatens its stability. The oasis internal salinization and secondary salinization are the key factors menacing its stability. In order to prevent the development of salinization and keep the oasis stability, the effective measures is to arrange water resource rationally and build the sound irrigation anddrainage system.6. Among the 10 evaluated oases, Fukang and Shawan Oases are in the approximate stable state, Cele Oasis is in the extreme unstable state, other 7 oases are in the unstable state and Minfeng Oasis is close to the critical value of extreme unstable state.