The Ecosystem Services Assessment of Wetlands based on the Classification of Hydrological-ecological Structures and Functions (Case study: Shadegan Wetland)

The wetlands are formed in the complex ecological, hydrological, and geological conditions, and supply a range of ecological services. Nowadays, there is the growing recognition of wetland services and benefits for human societies. Identifying and assessing wetland services as well as managing human and natural threats affecting it, in addition to maintaining the wetland ecological integrity, can also affect the economies of the local communities dependent on the wetland. Shadegan Wetland has been selected as a case study because of the diversity of its ecological structure as well as its crucial role in controlling the phenomenon of dust. The purpose of this study is to apply the ecosystem services concept in assessing and managing the wetland ecological conditions, which provides an approach for the continuation of service supply, optimal allocation of wetland resources and their effective management. Therefore, the hydrological-ecological framework has been developed based on wetland structural characteristics, functions, services and pressures imposed on them, in which two ecological and socio-economic spheres are its main structure, according to ecosystem service cascade model. The wetland classifications have been used to identify wetland structural and hydrological characteristics. The results show that Shadegan Wetland has been formed in three lotic, estuary and marine classes. The lotic part has a high potential for hydrological and biogeochemical functions such as water storage and detention, retention of sediments and particles, nutrient transformation, carbon sequestration, and all ecological functions. The marine- estuary part has a high potential for functions such as shoreline stabilization, nutrient transformation, carbon sequestration, aquatic habitat, the habitat water birds, and wildlife habitat; therefore, the Shadegan wetland provides numerous services (provisioning, regulating, habitat and cultural services). According to the compatibility matrix, the supportive and positive relationships are dominant between wetland services, and the most competitive relationship is between provisioning and regulating services. Due to the fact that Iran is a water-stressed country dominated by arid and semi-arid areas, wetlands are valuable places that lead to the preservation of the local climate and biodiversity. Destruction of wetlands and related services, due to the conditions of the country, have multiple social and economic consequences. In fact, the concepts of ecosystem services are known as an approach to analyze ecosystem conditions, and include several approaches and methods that interlink the three main concepts below:• The physical components of the ecosystem (structure),
• The functioning of and interaction between those components (process or function),
• The resultant contribution to human welfare from the ecosystem (benefit-providing service).
Selecting Shadegan International Wetland as a case study in this research, the ecosystem services approach have been applied to ecological conditions assessment of the wetland based on biophysical structures, processes, functions and ecosystem services in a hydrological-ecological framework, which provides a valuable tool for optimal allocation of wetland resources and their effective management, as well as adopting rational and sustainable policies. The proposed framework can be considered as a hierarchical approach based on the characteristics of biophysical structure, functions and ecosystem services. According to ecosystem service cascade model, the two ecological and socio-economic spheres are the main structure of the research. For investigating the factors affecting the wetland structure and basic ecological conditions in landscape scale, hydrology, geomorphology, and climate features are considered. The wetland classification have been used to identify the structural and hydrological characteristics of wetlands. The various steps of the proposed framework are as follows:- Investigating the factors affecting the wetland structure and basic ecological conditions;
-Identifying the wetland structural and hydrological characteristics;
- Identifying the biotic and abiotic characteristics of wetlands
- Identifying the most important wetland functions based on structural, hydrological and biotic characteristics;
- Identifying wetland ecosystem services and assessment of their potential supply based on structures and functions;
- Trade-off analysis of wetland ecosystem services through compatibilitymatrix;
- Identifying and assessing threats to wetland wetland services and providing management strategies. Information related to the wetland ecology, hydrology and geomorphology characteristics has been provided from previous studies, Wetland Management Plan, satellite imageries, Google Earth, field visits, interviews with experts of environmental department Shadegan and local people living in the villages within the wetland.
Investigating the factors affecting the wetland structure and basic ecological conditions, firstly,the climatic characteristics of the region for 17 meteorological stations in or near the Jarrahi Catchment during the period of 10 years (2008-2017) have been investigated. The results indicate that the average temperature during the year varies from 11°C in the winter to 36°C in the summer, and the average precipitation varies from zero to 200 mm; therefore, the rainfall regime is a Mediterranean in which the main part of rainfall occurs during the winter and autumn seasons.
In terms of hydrological andgeomorphological features, the northern part of the wetland has been formed from overflowing water of permanent rivers through the waterways, so the position of this wetland can be considered a lotic river.The water is fresh and its physical form is floodplain and water flow path is through flow. The southern part of the wetland is connected to the Persian Gulf and is flooded through the tidal waters of the Persian Gulf and estuaries. Therefore, the position is estuary-marine and its physical form is fringe. The wetland is subject to frequent tidal flood and a bidirectional tidal water flow path.The wetland can be divided into three distinct structural-functional divisions: floodplain lotic wetland with through flow; fringe estuarine with tidal flow; fringe marine with tidal flow. The lotic part has a high potential for hydrological and biological functions such as water storage and detention, retention of sediments and particles, nutrient transformation, carbon sequestration and all ecological functions.The Marine- estuary part has a high potential for functions such as shoreline stabilization, nutrient transformation, carbon sequestration, aquatic habitat, water bird habitat, and wildlife habitat. Shadegan Wetland because of structural conditions and ecological diversity and the belonging to three different wetland class, provides numerous services. According to the compatibility matrix, the supportive and positive relationships between the services of the wetland are dominant.
The management strategies are developed based on EBM-DPSER model and trade-off analysis of wetland ecosystem services.The most important management strategies include the following:-          Preparation of the wetland land use map and zoning of the wetland to appropriate and allowed areas for human activities;
-          Investigating existing livelihood patterns and providing alternative and eco-friendly livelihoods in the region;
-          Investigating existing livelihood patterns and providing alternative and eco-friendly livelihoods in the region;
-          Establishing a legal mechanism for allocating the right of water wetland from the upstream rivers and restoring the wetland share of the agricultural, industrial and energy sectors;
-          Identifying the main sources of dust and developing biomechanical and bioengineering plans using the existing capacities in the province, especially attracting local people's participation. The proposed framework has gone beyond the traditional approaches to assessing and managing wetlands, which have not yet been effective and are not based on the understanding of the structure and functions of wetlands. It also improves the process of wetlands assessing and managing in the country by applying an ecosystem services approach to identify the services and benefits of wetlands, main beneficiaries, threats to the services and provisioning the management strategies and decisions, in the form of indicators and conceptual models.