The Cost-effective Solution Of Intertidal Vegetated Habitat Restoration Planning

Intertidal wetland is recognized as one of the most productive ecosystems.It provides a series of valuable ecological products and services for human,most of them cannot be replaced by any reasonable price.However,intertidal wetland is ecosystem affected significantly by human activities.In the past 20 years,with the economic development,population growth,urbanization and lack of management,intertidal wetland habitat has been largely lost,which leads to the decrease of marine biodiversity,depletion of biological resources and continuous deterioration of marine environmental quality,directly threatening the sustainable development of coastal areas.Restoration of damaged intertidal wetland is thought as an effective way to maintain the health and resilience of coastal ecosystem.However,intertidal vegetated habitat restoration involves a large amount of costs.How to achieve the restoration objectives with least costs is one of the key topics in the intertidal wetland management.Therefore,this study establishes an ecosystem-based spatial planning model for vegetated habitat restoration in the intertidal zone based on the concept of system protection planning,the theories and methods of ecology and environmental economics,and makes a research of the lowest cost vegetated habitat restoration scale and its spatial pattern in Xiamen Bay by using the established model.The main results are as follows:(1)Based on the theoretical research of the suitability of vegetated habitat restoration,the key factors affecting the vegetated habitat restoration in the intertidal zone of Xiamen Bay are identified,and the index evaluation method for the suitability of vegetated habitat restoration is established,including the type of sediment,flooding time and so on.In this study,the suitability of two key vegetated habitats in Xiamen Bay is evaluated by using the established evaluation method.The results show that the intertidal wetland area of Xiamen Bay is 247.17 km2,the suitable restoration area of mangrove habitat is 183.28 km2,and the suitable restoration area of saltmarsh habitat is 174.30 km2.(2)Based on the principles of environmental economics and ecology,this study establishes the lowest costs spatial planning model of intertidal vegetated habitat restoration.The established spatial planning model not only considers the economic cost minimization of restoration,but also considers the connectivity between different vegetation ecosystems and the suitability of habitat restoration.The economic costs are represented by the planting costs and opportunity costs of restoration,and the ecosystem connectivity is represented by the total boundary lengths of restoration units.(3)In this research,the cost-optimal restoration pattern of intertidal vegetated habitat in Xiamen Bay is studied by using software tools such as Marxan,ArcGIS and Python.The results show that under the target scenario that the vegetated habitat restoration accounted for at least 10%of the intertidal wetland area,the total area of intertidal vegetated habitat restoration in Xiamen Bay is about 53.04 km2(including 26.90 km2 of mangrove restoration and 26.14 km2 of saltmarsh restoration),and the total restoration cost was 118 million yuan/year;Under this target scenario,the total area of the key priority restoration area of vegetated habitat(more than 60 times of selection)is about 14.15 km2(6.51 km2 for mangrove and 7.64 km2 for saltmarsh),accounting for about 5.73%of the total area of the planning area,and the total restoration cost is 11 million yuan/year,which is consistent with the largest coverage area of vegetated habitat in history.In addition,with the increase of the restoration target,the total costs are basically doubled.(4)This thesis compares the planning results of ecosystem-based restoration planning and administrative-division-based restoration planning.The results show that,compared with the ecosystem-based restoration planning scheme,the restoration spatial planning pattern of the administrative-division-based restoration scheme has undergone great changes,including an increase of 2.79 km2 in Xiamen,an increase of 7.92 km2 in Quanzhou and a decrease of 9.05 km2 in Longhai.From the perspective of restoration costs,the total restoration costs of restoration planning based on administrative region is 131 million yuan/year,which is 11%higher than that of restoration planning based on ecosystem.Assuming that the planning period is 20 years,it will need to pay totally about 125 million yuan more.Comparing the unit costs of the two planning schemes,it is found that the unit area costs of the restoration planning based on the administrative region is higher,with an increase rate of about 8%.In conclusion,ecosystem-based restoration scheme can achieve the goal of intertidal vegetated habitat restoration at lower costs.