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Conservation, restoration and effects of climate change on wetlands Dr Debbie Chapman School of Biological, Earth and Environmental Sciences University College Cork, Ireland NEAR curriculum in natural environmental science, vol. 2, 2010 Value of wetlands Essential habitat for rare or endangered species Commercial fisheries Recreational fisheries Natural improvements to water quality Overwintering habitat for waterfowl Reducing erosion and buffering storm impacts (coastal wetlands) Mitigating impacts of sea level rise (coastal wetlands) Wetland loss: examples UK East Anglian Fennland 17th Century: 3,380 km2 Present time: about 10 km2 USA 16th Century: 900,000 km2 Present time: 400,000 km2 (California and Ohio lost 91% and 90% respectively) Reasons for loss Natural succession (usually matched by creation of new wetlands) Drainage and reclamation to create agricultural land Lowering of water table through groundwater abstraction Interference with hydrological regimes (e.g. impoundment of rivers, coastal development) Tree stumps in the reservoir created by impoundment of a river for a hydrolectiricty scheme in Southern Ireland Degradation of coastal marshes Sea level rise and land subsidence need to be matched by sediment and organic matter accumulation Human activities are leading to an imbalance by decreasing sediment accretion Creation of barriers to landward marsh growth, e.g. roads, sea walls Harvesting of trees Disturbance of hydrological regimes A causeway has separated this wetland from the coast and created an artificial lagoon of less value to waterfowl Climate change projections Global mean temperature change from 1990: 1.4–5.8 °C Sea level rise: 10–90 cm by year 2100 Change in frequency and intensity of extreme climate events, e.g. increase in number of hot days, fewer cold days, more frequent intense downpours, increased frequency and intensity of floods and droughts The greatest changes in temperature and precipitation likely to occur in the northern hemisphere Possible impacts from projected extreme climate events Climate event Projected impact Higher max temps, heat waves Heat stress in wildlife Higher min temps, fewer cold days Extended range of pests and disease vectors More intense precipitation events Increased flooding, increased soil erosion, landslide damage Summer droughts Reduced water quantity and quality, risk of fires Intensified tropical cyclones (wind and rain) Coastal erosion, damage to coastal infrastructure, physical damage to coastal ecosystems such as mangrove swamps Climate impacts on wetlands It is likely that climate change impacts on water resources over the next 20 years will be small relative to the impacts of other changes Most likely impact on wetlands will be through alteration of hydrological regimes and occurrence of extreme weather events Climate change: Inland wetlands Change of plant communities Invasion or expansion of alien species Tropical wetland floodplains replaced with salt water habitats and salt tolerant species Loss of feeding/breeding grounds for birds and fish Interrupted migration Regular tidal inundation routes for birds leaves insufficient feeding area exposed for the birds Climate change: Coastal wetlands When combined with other human-induced losses, coastal wetland loss could be as high as 70% Vulnerable wetlands are low-lying deltas and coastal plains – estuaries, lagoons, salt-marshes, mangroves Climate change will lead to: Landward intrusion of seawater Coastal inundation and storm surge flooding Inland and upstream salinity intrusion Changes in ecosystem structure caused by changes in temperature and rainfall patterns Attempts to restrict coastal erosion have been abandoned at this beach in Western Ireland Projected impacts of climate change in Europe: inland wetlands Increased winter rainfall and river flows, leading to flooding Decreased summer flows and higher temperatures leading to low dissolved O2 and poor water quality Increased fish productivity and a shift towards cyprinid and percid fish Peatlands will expand northwards, possibly replacing tundra Loss of isolated depressional wetlands may affect migratory Evidence of a breeding population of carp in a and breeding bird populations shallow lake in Ireland Projected impacts of climate change in Europe: coastal wetlands Mediterranean and Baltic deltas, estuaries and salt marshes particularly at risk from sea level rise (extent of development on coasts restricts options for conservation/restoration) Possible loss of salt marshes and intertidal estuarine zones will reduce habitats for wildlife, fish and migratory birds Distributions of some shorebirds already occurring due to changes in regional temperature patterns Rhône, Po and Elbe deltas susceptible due to existing reduced sediment loads Erosion of rare estuarine peat saltmarsh in the West of Ireland Conservation and restoration Conservation - long-term preservation and protection of the functions and values of wetlands – returning a degraded wetland (rehabilitation) or former wetland (re-establishment) to a pre-existing condition or as close to that condition as possible Restoration Conservation of coastal wetlands for impacts of climate change Manage landward reinstatement of coastal wetland habitats through removal of sea defense structures Design multiple-use reserves and protected areas which incorporate corridors that would allow for migration of organisms as a response to climate change Expand aquaculture that could relieve stress on natural fisheries Integrated resource management Restoration: Passive Removal of cause of degradation and allow natural regeneration (e.g. removal of grazing livestock) Not always practicable (close access to water and wetland species essential) Low cost Likely that the resultant wetland will resemble the surrounding environment Restoration: Active Appropriate when wetland is severely degraded Examples: weirs and culverts, intensive planting, invasive species control, substrate creation Considerable design work needed Construction costs may be high The London Wetland Centre: Wetland restoration in the suburbs on London to create a bird reserve http://www.wwt.org.uk/visit-us/london Restoration: traditional versus soft engineering solutions Traditional “hard” engineering solutions replace natural ecosystem functions with human-designed structures, e.g. concrete embankments to prevent erosion “Soft” solutions include planting native species such as willows, log banks and geotextile materials Concrete embankments Restoration of banks along River Thames with native vegetation Restoration: important factors to consider Hydrology Topography Soil and geology type Vegetation and animal life Land ownership Stakeholder involvement Examples of wetland problems and possible remediation methods Problem Cause Restoration action Poor water quality Nutrient/sediment run-off, sediment erosion Change land-use practices, install vegetation buffers/sediment traps Altered hydrology due to drainage Presence of ditches and drains, embankment cutting off wetland from water source Fill ditches, remove embankment, install gates/weirs Raised elevation Dumping or in-fill Remove surplus material Subsidence Removal of soil, depletion of groundwater Allow natural sedimentation, add sediment Loss of biodiversity Change in habitat Planting of native species, allow species to recolonise, Loss of native plants Change in hydrology, change in land use, invasive species Restore hydrological regime, remove invasive species and alter conditions that favour them Restoration: usefulness and feasibility Will there be environmental benefits (e.g. improved water quantity, reduced eutrophication, biodiversity conservation, flood control)? What is the cost effectiveness of the proposed rehabilitation? What options, advantages or disadvantages will the restored area provide for local people and the region? What is the present and possible future ecological status of the project? What is the status of the area in terms of present land use? What are the main socio-economic constraints? What are the main technical constraints? http://www.ramsar.org/key_guide_restoration_e.htm Sources of information Ramsar Convention Secretariat, 2007 Inventory, assessment, and monitoring: An Integrated Framework for wetland inventory, assessment, and monitoring. Ramsar handbooks for the wise use of wetlands, 3rd edition, vol. 11. Ramsar Convention Secretariat, Gland, Switzerland. Ramsar Convention 2002 Climate change and wetlands: impacts, adaptation and mitigation. Ramsar COP8 Doc 11: Climate Change and Wetlands. Interagency Workgroup on Wetland Restoration (IWWR) 2003 An Introduction and User’s Guide to Wetland Restoration, Creation and Enhancement. US Environmental Protection Agency, Office of Water, 95 pp. http://www.epa.gov/owow/wetlands/pdf/restdocfinal.pdf USEPA, 2000 Principles for the Ecological Restoration of Aquatic Resources. EPA841-F-00-003. Office of Water (4501F), United States Environmental Protection Agency, Washington, DC. 4 pp.