A simple framework for evaluating regional wetland ecohydrological response to climate change with case studies from Great Britain

It is widely accepted that the Earth’s climate is changing more rapidly than it has in the past and that over the next 100 years temperatures will rise and patterns of precipitation will be altered. These predictions for the future have important implications for all ecosystems, particularly those, such as wetlands, whose ecological character is very dependent on hydrological regime. The potential impacts of climate change on wetland hydrology are of interest to a wide range of stakeholders from wetland managers to international policy makers. Ecohydrological models that combine climate changes, hydrological processes and ecological response provide a means of estimating what might happen to some wetland functions and species in the future. This paper presents a framework that can be used for combining models and available data at a regional scale and is appropriate for different wetlands, in different countries and for different levels of data availability. The simple models are based on broad conceptual understanding of wetland hydrology and are intended to describe basic ecohydrological processes within the constraints of data availability; they are thus fit for the purpose of general assessment and do not pretend to provide precise results for specific wetland sites. Data from Great Britain (GB) have been used to demonstrate each step in the framework for two temperate wetland types: rain-fed wetlands (wet heaths or degraded raised mires) and floodplain margins. Whilst GB may be considered to be relatively data rich, we believe that sufficient information is available in many countries to apply this framework for the regional assessment of climate change impacts on wetlands. Although the models successfully represent the baseline conditions, it is not possible to test whether they accurately predict the future vulnerability of the selected areas. Results for GB suggest that predictions of reduced summer rainfall and increased summer evaporation will put stress on wetland plant communities in late summer and autumn with greater impacts in the south and east of GB. In addition, impacts on rain-fed wetlands will be greater than on those dominated by river inflow