跨区域视角下苏锡常地区白鹭生境网络优化

Habitat network optimization from across⁃regional perspective:A case study of the little egret in the Su⁃Xi⁃Chang area

打破行政界线,跨区域协同治理生态问题,是生态文明建设的必然要求。选取快速城镇化地区苏锡常为研究区域,地区优势物种白鹭为研究对象,在等量保护成本限定下,基于跨区域和分区视角,将保护成本用于生境斑块优化,通过设定不同的优化情景,确定新增生境斑块的优化顺序,计算出各情景下生态保护成本与生态收益提升值,对比不同优化方案下网络结构指数变化情况,进而探讨跨区域生境网络优化是否能够更好地实现物种保护的“最大覆盖问题”。结果表明:(1)新增生境斑块的总量和空间布局都呈现为不均匀分布,以苏州最多,无锡次之,常州最少;具有“网络连通性较高但保护成本较低”的斑块分布特征与之相同;(2)根据单位效益成本值大小对生境斑块优化排序,将保护成本优先用于“网络连通性指数较高而保护成本较低”的生境斑块。在等量保护成本限定下,跨区域生境网络优化比分区优化的网络连通性指数α、β、γ分别提升了13.17%、12.97%、13.76%,实现保护成本的生态效益提升最大化,更好地解决了物种保护的“最大覆盖问题”。

The breaking down of administrative boundaries,control of ecological issues,and protection of biodiversity through trans⁃regional intergovernmental cooperation,are inevitable steps inecological civilization processes.Newly added habitat patcheseach havean obvious variance on ecological conservation costs andalso contribute to habitat network connectivity;the costs spent by each administrative unit on ecological protection and biodiversity conservation are also different.As such,scarce land resource and limited funds may leadto lower ecological conservation efficiency per unitcost in some areas.It is therefore necessary to focus on the issue of cross⁃regional ecological protection and biodiversity conservation.However,the questions as to whether cross⁃regional cooperation is effective or not,and how it can be realized require further exploration.In this study,we applied ecological processes and comparative analyses to discuss habitat network optimization of a target specieswith different scenarios.Specifically,we selected the rapidly urbanizing area of Su⁃Xi⁃Chang as a cross⁃regional perspective case study,and the dominant little egret waterbirdas the target species.Furthermore,we discussed the differences of habitat network connectivity under scenarios of equal conservation costs but different spatial⁃location modes.We designed the optimizing sequence of newly added habitat patches,calculated both its ecological protection cost and the increased ecological benefit value,compared the changes in habitat network connectivity,and explored howthe maximal covering problem of species conservation would be better achieved.Ourresults indicated that:(1)newly added habitat patches are unevenly distributed in different regions,with the largest in Suzhou,followed by Wuxi,and Changzhou;thepatches thathave higher network connectivity and lower conservation costs have the same spatial distribution trend.(2)According to the cost⁃benefit ratio,conservation cost was preferentially used on the patches of a higher network connectivity index but of a lower conservation cost,both in the partition as well as the cross⁃regional scenarios.Under the same condition of a total limited conservation cost of 182 million RBM,habitat network connectivity indicesα,β,andγof the scenario of cross⁃regional habitat optimization increased by 13.17%,12.97%,and 13.76%more,respectively,than those of the scenario of partition network optimization.Thus,cross⁃regional habitat network optimization maximizes ecological benefit under limited conservation costs.As such,it can be concluded that it is a better way to realize the maximal covering problem of biodiversity conservation.