Abstract: Ecosystem services valuation has made certain progress, but double counting still occurs. At present, most of the previous approaches to the assessment of wetland ecosystem services focus on the simple classification of services, trying to use the economics method to calculate and evaluate wetland ecosystem services value. The generation, transmission, consumption and reproduction of the ecosystem services are cycle processes. If we only evaluate the value by simple classification, the accuracy of the results will be affected, easily leading to double counting. If this double counting problem cannot be removed appropriately, the credibility of the evaluation results will be reduced. By establishing the flow chart of emergy, this paper analyzed the three basic mechanisms-‘separation, feedback, and coproduct’ in the wetland ecosystem services to avoid the double counting error. At last, we compared the calculated results with precondition to the results without precondition, and the error range was from 12% to 38%. Our results indicated that associating with emergy and the preconditioning analysis of the system can remove the double counting effectively and make the evaluation results more accurate.

Key words: low temperature, brassinolide, salicylic acid, cucumber (Cucumis sativa), photosynthesis