Abstract:
Background The Zoige Plateau is the most important ecological function area in the eastern margin of the Qinghai-Tibet Plateau, and is also a sensitive area of climate change and ecological environment, with the largest alpine marsh in the world. With warming of global climate and enhancement of human activities, the Zoige Plateau alpine wetland is faced with the environmental problems such as the area shrinkage, the deterioration of animal and plant habitat, and the degradation of ecosystem structure and function. Protecting the local unique ecological environment and exploring the best way to restore the ecology of alpine wetland have become the focus of current research, and are also the research objectives of this paper.
Methods Taking the Zoige Plateau alpine wetland as the research object and based on land use data, wetland landscape evolution function was adapted to analyze the dynamic changes of wetlands in seven periods from 1980 to 2015. Based on the data of ecological and economic benefits of various finished products, the NSGA-Ⅱ (non-dominated sorting genetic algorithm Ⅱ) was applied to calculate multi-scenario and multi-objective function values, and to compare the differences of the function values. Finally, according to the principles of sustainable development and ecosystem stability, appropriate function results were selected to formulate the optimization strategy of wetland restoration.
Results 1) Sustainable development area, over-concerned area, and over-disturbed area accounted for 45.25 %, 17.27 % and 37.48 % of the total wetland area, respectively. On the whole, there were many unreasonable restoration behaviors and over-utilization behaviors in the Zoige wetland. 2) Based on the principles of sustainable social and economic development and ecological protection, a multi-objective optimization model for ecological restoration of Zoige Plateau alpine wetland was constructed. With the help of the NSGA-Ⅱ algorithm, the wetland restoration strategies with five objectives were evaluated, including no preference (equal weight optimal), maximum economic benefit, maximum ecological benefit, maximum spatial compacity and maximum restoration suitability. As the optimal land use scheme, the function value of no preference strategy increased by 41.45 % in economic benefit, 9.18 % in ecological benefit and 1.65 % in wetland restoration suitability respectively. 3) The spatial optimization pattern for the ecological restoration of four types in Zoige Plateau wetland was constructed, which gave priority to conservation, combined with natural restoration, near-natural restoration and moderate restoration. The area proportions of the four restoration methods were 57.93 %, 16.08 %, 17.50 % and 11.67 %, respectively.
Conclusions Most areas of the alpine wetland of the Zoige Plateau are sustainable development areas, and the proportion of over-disturbed area is bigger than that of over-concerned area. It presents a spatial pattern with the sustainable development area as the center and other regions around the sustainable development area. According to the optimized allocation results for conservation and sustainable utilization of wetland resources, no preference strategy and optimization partition scheme can provide support for management of alpine wetland. The optimization method can be easily adapted to other regions by modifying the fitness functions and findings can provide a more scientific reference for the conservation and restoration plan of alpine wetland.