雄安新区上游白洋淀流域水质净化提升目标下的生态恢复格局优化

Optimization of ecological restoration pattern targeted for water purification improvement in the Baiyangdian watershed,Xiong′an New Area

白洋淀流域是雄安新区重要的淡水来源之一,流域内退耕政策在改善水质同时大幅降低了农田面积。如何通过退耕空间规则的优化权衡水质净化效率与农田面积是亟待解决的问题。通过设置基于不同退耕规则的情景,并与实际情景对比,提出了退耕规则的优化方案。结果表明:相同面积下,河岸带退耕的水质净化效率高于坡耕地退耕;相同退耕规则下,退耕还林驱动的水质净化效率高于还灌,还草;单位面积河岸带退耕的水质净化效率随缓冲区距离增加而降低;300m河岸带退耕还林情景下的水质净化率提升高于其他所有模拟情景,也比实际退耕情景(2015)高,同时农田面积降幅也低于实际情景。研究表明通过对退耕规则进行空间优化不仅能够满足区域水质净化提升的目标,还有利于保障区域农田面积,减少生态系统服务间的权衡。

Baiyangdian watershed is one of the important freshwater sources in the Xiong′an New Area.To protect the ecological environment,a series of ecological restoration projects have been implemented since the 1980s.The projects improved the ecological environment but with the reduction in farmland area as cost.Therefore,this study tried to find a better way to optimize the rules of the farmland conversion to reduce trade⁃off between the improvement of water quality purification and the decrease of farmland area by setting up different scenarios of farmland conversion.The results show that:In the condition that converts farmland with the same area,the efficiency of returning farmland in the riparian zone is higher than the slope field;In the condition that converts farmland under the same rule,the water quality purification efficiency of returning farmland into forest is higher than returning farmland into shrubland or grassland.The improvement rate of per unit water quality purification is reduced with the increase of buffer distance in the riparian zone.Under the scenario that returning farmland into forest in 300 m riparian zone,the improvement of water quality purification rate is higher than that of the actual scenario(2015),but the reduction in farmland area is lower than that of the actual scenario(2015).By optimizing the rules of returning farmland,the pattern of ecosystem restoration can be appropriately optimized.And it is not only conducive to improve the target ecosystem services,but also reduced trade⁃off between different ecosystem services improvement goals.