Research On Ecological Security Evaluation Of Coastal Wetland

Coastal wetland is a special ecosystem by the interaction of ocean and terrene, presenting one of the most abundant biodiversity, high productivity and most valuable ecosystems. Coastal wetland plays an important role in protecting biodiversity, flood control, remediate seawater intrusion, recharging groundwater, climate control and providing inhabitation for wild animals. Moreover, the natural resource in coastal wetland is prerequisite to the sustainable development of fishery, salt industry and salt chemical industry. With its significant influence on local, national and global economic development and human living environment, coastal wetland has become one of the hot international research topics.There are many types of coastal wetland with abundant resource in the coastal zone in Qinzhou, Guangxi province, mainly mud flat, mangrove wetland, shallow sea area and artificial culture pond. Gaungxi Maoweihai national ocean park project was approved by the state, to coordinate the oceanic ecologic protection and resource utilization and promote the economic sustainable development in coastal area. It is critical for ecological environment of Qinzhou.But the coastal wetland has been reduced due to long-term human activities by over exploration of the wetland resource and hysteretic protect program of the wetland. Large area of the wetland has been replaced by artificial wetland and residential area. The ecosystem of coastal wetland is being threating to a serious of wetland problems, including wetland shrinking, bio resource reducing, environment pollution, deterioration of ecological environment and reduction of wild animals’ inhabitation.Eco-security refers to a state that the survival and development of the ecological environment of human society is not subject to destruction or threatened. With the growth of population and socio-economic development, the environmental and ecological disasters on regional development caused by environmental degradation and ecological damage, has become a growing threat to national security and social progress. Ecological security problems as the theoretical and practical problems that need to be addressed.Therefore, the ecological security evaluation of coastal wetlands in Qinzhou by exploring the theories and methods of ecological security evaluation of coastal wetlands provides scientific basis to resolve coastal conflicts between wetland eco-security and socio-economic development and to the eventual realize sustainable development of local resources, environment, economy and society in Qinzhou.This study established landscape classification system, and by collecting landscape information carried out interpretation analysis on coastal wetland landscape changes in Qinzhou. The dissertation is based on multiple source remote sensing data and the non-remote sensing data from the tide up to10km from1999-2011, employing remote sensing image processing software and geographic information systems. Combining the "pressure-state-response"(PSR) framework model, using analytical hierarchy process, this study built a coastal ecological safety assessment system including a number of19evaluating indicators such as population, economy, ecology and landscape. Quantification of relating indicators was carried out to investigate temporal change characteristics of Qinzhou. In the other hand, on the spatial scale, three different geographical regions, Mao Weihai, Qinzhou port fields, Sanliang Bayand Wind River estuary were investigated to explore the inner mechanism of security patterns change. Based on the ecological security assessment results, control measures of sustainable development of Qinzhou coastal wetland eco-systems was proposed to explore the connection of ecological security research and integrated coastal zone management, providing scientific reference for the protection of wetland resources and regional sustainable development. The main conclusions are as follows:1. Under the guidance the theories of sustainable development, landscape ecology, ecological carrying capacity theory and systems theory, the research focus of this dissertation is ecological security of wetlands in the study area. There are complicated subsystems in coastal wetland eco-system due to resources, environment and socio-economic factors. Coastal wetland eco-security situation is the result of conflict and coordination between the subsystems. The coordination and interaction between the subsystems result the coastal wetland eco-system from a state of disorder into order status, leading to the achievement of ecological security status, so as to achieve the objectives of sustainable development in Qinzhou coastal wetlands. This dissertation provides theoretical basis for ecological security evaluation index and evaluation method selection by analyzing the impact ecological security assessment for coastal wetlands and providing the inner mechanism of ecological security status.2. The dynamic change patterns of wetland landscape and wetland landscape characteristics are an important indicator of wetland ecological security status, and the background data base for wetland ecological security evaluation. Landscape diversity, fragmentation of the landscape, fractal dimension parameters are important parameters of the structure and ecological function of wetland. Applying the landscape ecology principle, after several field investigations, the TM, SPOT and ALOS remote sensing image data of the study area were used for wetland information extraction by interpretation software ERDAS. According to the consistency of wetland type spatial morphology, vegetation cover characteristics and wetland landscape image characteristics, combined with the wetland eco-security evaluation, the coastal wetlands in study area can be classified into natural wetlands and artificial wetland. The natural wetlands includes mangrove wetland, muddy tidal flats, shallow sea water and sand beaches; the artificial wetland mainly consists of artificial ponds and paddy fields. In order to better perform the characteristics of wetlands and other land-use conversions, this study also focused on the translation and analysis of non-wetland type (urban construction land, woodlands). The dual employment of GIS software and landscape pattern analysis software is an advanced method to reveal the characteristics of wetland landscape pattern and the variation of wetlands, also as well as an effective method to study the wetland landscape pattern and its ecological processes. All wetland types in the entire area has undergone significant change and frequently transfer. The primary change of natural wetlands is their alternation to farmed shrimp ponds and construction land, which has a certain negative effect on maintaining biological diversity and ecological functions of the study area. The changes of coastal wetland landscape are as follows:Related wetlands area and structure. In1999, the dominant type of coastal wetlands in the study area were shallow sea area and muddy tidal flats, which was approximately60%of total regional wetland area. The main non-wetland was woodland, as18.94%of the area. During1999to2006, the main types of wetlands in the area had little change. The relatively higher increase of the non-natural wetland was artificial ponds, increased from3.31%to5.58%of the area.Drastic reduction of natural wetland. During1999to2011, muddy tidal flats, mangrove wetlands, shallow sea area and other natural wetland has a total reduction of12643.1hm2, while artificial wetland has an increase of10690.3hm. As the natural wetland reduction, muddy tidal-flat area declined20.15%as3526.1hm2. There is a considerable reduction of mangroves of1.33%from1999to2011. In2005, flaps sonneratiacaseolaris mangrove was planted to retain the reduction of mangrove wetland. Sand beach area generally remained on stability. Sand and gravel beaches are mainly located in Rhino foot, Sanniang Bay area with a relatively small conversion ratio to other wetland types. Shallow sea area decreased with a more and more fast speed. In1999-2006, water area reduced1339.7hm2and in2006～2011decreased4867.6hm2, with a large scale reduction. The main cause of the reduction of sea area is the large area and reclamation of tidal flat reclamation culture.Substantial increase in artificial wetland landscape. Changing paddy field area has decreased. In coastal areas, due to the much higher income from mariculture than that of crop cultivation, acres of farmland were converted into shrimp ponds salt filed. In the study area, non-wetland is increasingly changed into construction land. According to statistics, in2006-2011, the reclamation area in Qinzhou Bay is approximately480hm2, which is used as sea transportation (port, dock), entertainment and travel sites. Most the conversion happened in2008-2010. Reclamation reduced the biodiversity of landscape.Spatial distribution of wetland landscape. In the last decade, the general variation tendencies of Mao Weihai, Qinzhou port fields, Sanniang Bay and Wind River estuary are: considerable reduction of muddy tidal flats in Mao Weihai, Sanniang Bay and Wind River estuary; significant increase of artificial ponds (shrimp pond) area expansion; large increase of urban construction and traffic land in Qinzhou port; no significant alteration of sand beach area. Based on landscape characteristics index, in1999-2011. landscape diversity and fragmentation in the study area has increased resulted from strong anthropogenic activities.3. Pressure-state-response, PSR model framework is the one most popular models for ecological safety evaluation. It represents the interaction and relationship between human-being and the environment. In the model,’state’ of environment ecological resource is used to reflect the degree of environment changing;’pressure’ is the factors that give pressure to the environment due to regional economic activity, social structure and human disturbance;’response’ is the people’s reaction due to environment change, reflecting the reactions of stopping, releasing, preventing or recovering the factors which are against the development of human and the environment. it is widely recognized and used for very clear causal relationship between the model system, but also has a comprehensive and flexibility advantages.4. This study is based on the PSR model framework, under the advises of experts and environment/ocean related department, according to the principles of holistic principles, scientific, dynamic and operability, using Analytic Hierarchy Process, to build a three-level, containing17indicators of wetland ecological safety evaluation index system. The concrete steps are:①establishing the index system;②selection of evaluation methods;③evaluation standards and classification;④determination of evaluation cell;⑤calculation of ecological security indicators;⑥evaluation of ecological security.Indicators of the system are divided into three layers:the target layer, criteria layer and index layer. Highest target layer of the system:(A) Security status of Qinzhou City coastal wetland ecosystem. Results using the ecological security level. Criteria layer consists of pressure (B1), state (B2), and response (B3) the three subsystems. Pressure system is reflected by resources, environmental pollution, and the humanities and social indicators. State system is reflected with soil, biological, vegetation, water resources, and socio-economic indicators. Response system inclues ecosystem response, economic response and the humanities and social response, in response to the changes of the wetland ecological security state. It reflects the the solution of environmental problems by ecological system itself. Index layer (C) is the most basic level of the index system guidelines layer indicators of the specific characteristics of indicators, constituted by measurable indicators. The index system architecture not only reflects the common requirements of the regional ecological security assessment, but aloes designed for both coastal wetland ecological security evaluation.According to studies of the wetland ecological security evaluation standard in both domestic and overseas, in accordance with the level of comprehensive evaluation score, from highest to lowest, divided into safe, safer, early warning, fragile, dangerous five levels, the Composite Index being [0.8,1],[0.6,0.8],[06,0.4],[0.4,0.2],[0.2,0], in order to reflect the wetland ecological safety degree from good to bad. Different level are defined from the three main characteristics of vigor, structure and resilience, from high to low. Such as whether landscape maintaining the natural state; wetland type structure being complete, the ecological function being perfect, the ecosystem vitality exists or extent, the ecosystem being a stable and sustainable state, the existence of state appeared abnormal or not, how ecological restoration functioning well etc.. For the ecological security rating, there are certain assessment standards which can be considered as the characterizations of wetland ecosystem health and criterion basis of ecosystem safety.After evaluation criteria and grading system established, using three section of the study area, Qinzhou port in Maowei Sea section, Sanniang Bay and the estuary as evaluation units, evaluated the security situation in the Gulf of Qinzhou coastal wetland ecosystem in time and space dimensions.5. On the timescale, according to the results of ecological security evaluation if Qinzhou Bay, the ecological security of the study area is relatively safe level. Though it has decreased gradually from1999to2011, followed by the Maoweihai area. The ecological security of Qinzhou Bay has deteriorated.6. As the spatial pattern, Sanniang Bay in Qinzhou Bay and Wind River estuary region have the best security assessment, followed by Maoweihai area and Qinzhou port area, with the safety index of0.845,0.793and0.726respectively. The wetland types of Sanniang Bay and the Wind River estuary are mainly sandy coast and shallow sea area, less-human disturbance. Based on the marine functional division, Wind River was classified as mangrove nature reserves, where the wetland protection measures are relatively more effective; Maoweihai area mainly consists of muddy tidal flats that are easy transferred into artificial ponds. Near the urban area of Qinzhou city, coastal development has a long utilization history, where the wetland has been significantly influenced by human activities. Although there are two wetland protection units--the Qinzhou Bay National Ocean Park, and Guangxi Maoweihai mangrove reserve, the natural coastal wetlands area declined significantly and degraded quickly; After nearly a decade of industrial-scale development along the coast, large areas of land reclamation, natural wetlands in Qinzhou port experienced severe damage.7. Coastal wetland eco-security of the Qinzhou Bay is facing a severe test. In the last decade, the evolution of coastal wetlands Qinzhou Bay resulted from both the natural and human disturbance. Natural factors include water dynamic changes in coastal regions, river sediment, tidal volume reduction, biological invasions caused by the reclamation, biological invasion, and so on, meanwhile the interfere with human factors and economic factors. Factors as wetland Resource overexploitation, enormous pressure from the peripheral port construction, inadequate management systems, inadequate funding, lead to reduction and degradation of coastal wetlands. Deeply thought, coastal wetland ecological security is the conflict and coordination combination of the four subsystems--resources, environment, economic and society. The conflicts include the conflict between economic interests and wetland protection of Qinzhou Bay, the conflict between long-term and short-term utilization of wetland resources, and the conflict of resources plunder due to different regional interests. Incoordination during the competition between different subjects in resources using and benefit-seeking has made coastal wetland ecological security faced serious of pressure and challenge. Only the coordination and mutual effect of subsystems of resource, society, economic and ecology can make coastal wetland ecosystems from random chaos into orderly state and achieve regional ecological security.8. Based on the above analysis of coastal wetland eco-security mechanism of the influence of the Qinzhou Bay, therefore, measures of ecological safety include the pressure control of ecological security, the restoration of ecological functions and improvement of the ecological response efficiency. The fundamental measures to improve coastal wetland eco-security of the Qinzhou Bay are controlling the ecological safety pressure, appropriate exploitation of coastal wetlands resources, in the long run to balance the resource exploitation, the economic development, social progress and ecological safety, constantly adjusting the industrial structure, governance of Qinzhou Bay land and sea pollution, pollution source control. At the same time, the current coastal wetland ecological of Qinzhou Bay need to be restored, and steps need to maximize Qinzhou Bay Ocean National Park and Guangxi Maoweihai Mangrove forest reserve effectiveness. Improvement of the ecological response requires effective organization of the wetland regulation system, strengthening ecological research and to promote public participation, to improve ecological security management and recovery capabilities of coastal wetlands in Qinzhou Bay.