基于能值的绿洲种植业系统可持续性及敏感性评价——以新疆渭干河流域为例

利用能值理论与方法对2000～2006年新疆渭干河流域种植业系统的可持续性与敏感性进行分析,研究结果表明:(1)种植业系统的能值总投入逐年上升,不可更新工业辅助能与可更新自然资源能是种植业系统主要的能值投入类型,地均能值投入在上、中、下游呈递增趋势;(2)种植业系统的能值总产出呈现逐年上升趋势,地均能值产出在上、中、下游依次增加,棉花是中游与下游重要的能值产出作物,玉米、小麦是上游主要的能值产出作物;(3)中游种植业系统的可持续发展指数较高,近年来基本处于稳定状态;上游与下游可持续发展能力偏低,并且表现为连续下降的趋势,形成上、下游可持续发展指数偏低的本质原因差别较大;(4)种植业系统对可更新自然资源能的变化响应较弱,对不可更新工业辅助能变化的响应最为明显;下游种植业系统在环境改善或恶化的情景下响应最为敏感,上游种植业系统对环境变化的响应较弱.

Emergy\|based sustainability and sensitivity analysis of oasis cropping system: a case study in Weigan River Basin

Based on emergy synthesis, the cropping system of Weigan River Basin in Xinjiang is chosen as the research object for the exploration of its sustainability and sensitivity from 2000 to 2006. The cropland in Weigan River Basin, a typical mountain\|oasis\|desert system in arid regions, increased rapidly in recent decades and has covered more than 50% of the oases presently. This expansion led to some ecological and environmental problems, which were revealed by the emergy indicators in this research. The results indicate that (1) the total emergy input in the whole basin increased gradually during the concerned period with non\|renewable fuels and renewable environmental resources as the major input into the cropping system, and the emergy input per unit area of cropland increased from the upper to lower reaches; (2) the emergy yield of the cropland increased each year and the emergy yield per unit area increased from the upper to lower reaches, with cotton as the major crop yielding emergy in middle and lower reaches, and maize and wheat for the upper reaches; (3) the Emergy Sustainability Index (ESI), which measures the incremental emergy yield compared to the environmental load, was the highest and relatively stable in the middle reaches due to abundant water resource, high vegetation cover and appropriate non\|renewable fuels input. Comparatively, the ESI in the upper and lower reaches were lower, of which the intrinsic drivers were totally different; (4)As to the sensitivity analysis, the cropping system responds more to the change of non\|renewable fuels than that of renewable environmental resources. Also, it is more sensitive in the lower reaches than in the middle and upper reaches.