Coastal Ecosystem-based Management In Chongming Dongtan

The conditions of resources and environment in coastal area are considerably superior, and very beneficial to human survival and development. With a large increase of population and human activities, coastal zone is facing huge pressures such as the global climate change, sea level rise, regional ecological environmental damage, biodiversity decline, aggravating pollution, and fishery resource degeneration, which has a serious impact on the sustainable development of the coastal zone. It has become a major scientific issue related to the sustainable development of coastal area, to implement the coastal ecosystem-based management (EBM) to coordinate the relationship between the regional comprehensive carrying capacity and the sustainable economic and social development in coastal areas.As a case study of the implementation of coastal EBM, the Chongming Dongtan coastal zone was chosen as the study area in this study. Based on the EBM implementation framework firstly, the ecosystem management principles and objectives for Dongtan coastal zone were put forward. Secondly, by means of the spatial analysis function of ArcGIS, the historical process and influence factors of ecosystem dynamic changes were explored; and meanwhile, by creating the habitat assessment models and using the mathematical statistics method, this paper analyzed the present situation characteristics of the natural wetland ecosystem, agricultural ecosystem and urban ecosystem, to identify the main intersystem and intrasystem problems. Finally, applying the Markov model, multi-objective linear programming model, the linear and nonlinear regression model and based on the simulation platform including ArcGIS, Stella and WinQSB, the scenario simulations and analyses for the future ecosystem situations were given to make reasonable management options, and formulate the corresponding management countermeasures. The main results of this study are as follows:(1) The results about ecosystem dynamic characteristic analysis showed that the ecosystem dynamic changes in Dongtan coastal zone were influenced and controlled by the three main factors including the wetland reclamation, variation of agricultural land use and spread of Spartina alterniflora. During the period 1990-2000, the area of Phragmites australis and Scirpus mariqueter communities declined sharply, due to the several large-scale wetland reclamation, which thus significantly changed the area proportion of agricultural ecosystem and natural wetland ecosystem in the entire study area. During the period 2000-2008, the invasion and spread of Spartina alterniflora had a strong inhibition on the growth of native vegetation. The area of Spartina alterniflora community, in this period, increased by more than 8 times, while those of Phragmites australis and Scirpus mariqueter communities declined slightly. The quantity structure and spatial distribution of land use types in agricultural ecosystem, due to the effect of wetland reclamation, market benefit and policy change on them, varied greatly and frequently; especially the aquaculture pond, its construction and abandon presented considerable casualness. Therefore, the future ecosystem management for the Dongtan coastal zone should pay more attention to the issues like exploring the reasonable wetland reclamation strength, artificially controlling the invasion and expansion of Spartina alterniflora community, and making the spatiotemporal patterns of land use types in agricultural ecosystem tend to be rational and stable.(2) The results about the present situation analysis for the natural wetland ecosystem (here mainly related to the waterbird habitat status) showed that:1) During the period 1990-2008, the quantity structure of suitable habitats for waterbirds in Dongtan coastal zone (with a range from 3000m inside the dike to 3000m outside the dike) underwent changes from natural dominance through artificial dominance to natural dominance again. Dramatic or highly abnormal habitat changes were observed in aquaculture pond (AP) and Scirpus mariqueter community (SMC) during certain periods, while the habitat variations of bare mud flat and shallow water areas (BSA) and total suitable habitat (TSH) were within normal or slightly abnormal levels. The fluctuation intensity differed among habitat types in the order AP> SMC>TSH> BSA.2) The highest values of advantage degree index of habitat (ADIH) for SMC and AP occurred in the years of 1990 and 2003, while the lowest values in the years of 2000 and 2008, respectively. The main reasons leading habitat status of SMC and AP to deterioration were large-scale wetland reclamation, Spartina alterniflora invasion, massive abandon of AP, and increasing human disturbance.3) At present, Anatidae and Ardeidae (especially their rare and endangered species) have been threatened with declining population viability because of the extreme instability of their preferred habitats. Charadriidae may have experienced enormous population declines in the late 1990s but currently suffer less severe impact due to the lower intensity of habitat changes.(3) The results about the present situation analysis for the urban and agricultural ecosystems showed that:1) The main problems currently occurred in urban ecosystem are that the urban green space system and ecological infrastructure have not been constructed adequately, and the environment pollution pressure are increasing. Additionally, the urbanization level is not high, and the industrial structure is not reasonable.2)The main problems of agricultural ecosystem are that the ecological and economic benefits are lower, which refers concretely to that the application amount of chemical fertilizers and pesticides are considerably high, and with an increasing non-point source pollution; meanwhile, the output benefit of per unit of land is lower because of the traditional production mode.(4) The results about the scenario simulation for future ecosystem dynamics from 2008 to 2018 showed that:1) The changes of wetland reclamation strength have a significant effect on the dynamic changes of natural wetland ecosystem, agricultural ecosystem and urban ecosystem, as well as on the spatiotemporal pattern of the entire Dongtan coastal zone. When the land transition probability from salt marsh vegetation communities and mudflat and sea water area to agricultural ecosystem is declined to 35% of that from 1997 to 2003, it will reach a basic balance between the wetland reclamation rate and the natural growth rate of marsh wetland. Under this scenario, the total area of salt marsh wetland in 2018 will not be lower than that in 2008 when more than 1200 hm2 of salt marsh wetland is reclaimed and exploited in 2018. This scenario can reach a balance in resolving the wetland requirement conflict between the economic development and ecological protection, and follows a management principle of managing natural resource which gives a simultaneous consideration to the protection and utilization, therefore, it provides a reasonable way to realize the harmonious development of human and nature.2) The area of Spartina alterniflora community will be nearly 2 times that of Scirpus mariqueter community in 2018, if the invasion and expansion of Spartina alterniflora is not artificially intervened and controlled. On the other hand, if the Spartina alterniflora community in the key area controlling invasion is artificially intervened and further changed into a semi-natural pond in 2013, the average annual growth rates of the Spartina alterniflora community and Scirpus mariqueter community will significantly decrease and increase, respectively, which makes the quantity dynamics of Scirpus mariqueter community change from the decline before 2013 to the rise after 2013, and its area will be close to that of Spartina alterniflora community in 2018. In addition, the semi-natural pond transformed from Spartina alterniflora community can be serve as a suitable habitat for some waterbird species, so this scenario can bring higher ecological benefit, and accords with multi-objective management to the Dongtan coastal natural wetland.3) The land use structure optimization, will make the spatiotemporal pattern of agricultural ecosystem change obviously like that the area of woodland will increase significantly; the extensive aquaculture pond will be recovered its area from the current status (nearly have disappeared) to average level between 2003 to 2005; wasteland, farmland and rural residential area will drop substantially; and the total area of the two newly introduced land use types(i.e., riparian buffer woodland and eutrophic water storage pond) will be remained an area scale similar with the rural residential area. The land use structure optimization will considerably enhance both ecological and economic benefits of agricultural ecosystem.4) From 2008 to 2018, the area proportion of public green space and per capita construction land area in total urban area will obviously increase and decrease, respectively. The discharge amount of environmental wastes including the urban domestic sewage, urban household garbage, industrial solid waste and industrial wastewater in 2018 will be 2-3 times that in 2008. In order to make the total amount and concentrations of a variety of wastes to be discharged into the environment meet the requirements of environmental self-purification capability, the corresponding artificial waste disposal ability should be at least improve 1-2 times in 2018.(5) The corresponding management countermeasures for the three types of ecosystems in Dongtan coastal zone should be taken:1) for the natural wetland ecosystem, including moderately developmenting the saltmarsh vegetation zone, artificially controlling the invasion and spread of Spartina alterniflora, coordinating the use ways of wetland resources, and overall considerating multiple problems for the multi-objective management; 2) for the agricultural ecosystem, including optimizing the land use structure, training and teaching the agricultural implication technology, coordinating the conflicts between the stakeholders, and intensively occupying the rural residential area and improving the production and living environments; 3) for the urban ecosystem, including strengthening the construction of urban public green space and public infrastructure, optimizing the industrial structure, building more environment waste disposal facilities, and encouraging public participation in urban management and planning.