Ecosystem services of wetlands and wetlandscapes under hydro-climatic change : Impacts of water flow and inundation patterns

Sammanfattning: Wetlands provide ecosystem services valuable for human society and are therefore often considered as nature based solution to different environmental problems. However, with centuries of wetland degradation due to anthropogenic pressures, such as agricultural expansion and forest industry, as well as pressures from climate change, there are large challenges for sustainable wetland management. Thus, for wetland protection and restoration practices to be successful, a deepened understanding on the actual mechanisms controlling wetland functions is required. Understanding how wetlands are connected, with and influenced, by their surrounding environment is also needed. Although most pressures experienced by wetlands operate on scales beyond the individual wetland scale, relatively few studies have thus far addressed large-scale functions and ecosystem service provision from hydrologically interconnected wetlands at the scale of wetlandscapes (i.e., the wetlands’ aggregated hydrological catchments in the landscape). The aim of this thesis is to investigate ecosystem service delivery from wetlands and wetlandscapes under hydro-climatic changes, considering 25 different wetlandscapes located in four different climate zones of the world. The thesis also systematically quantifies ecohydrological characteristics important for ecosystem service delivery and biodiversity support of wetlands and wetlandscapes in the Norrström Drainage basin located near Stockholm, Sweden. Conducted hydro-climatic analyses showed that impacts of climate change on wetlandscapes cannot be fully understood from average changes in climatic variables of the climate zones within which the wetlandscapes are located. This may be due to the fact that wetlands are not randomly and evenly distributed within climate zones, but may be located in areas subject to stronger climatic changes than regional means. In addition, anthropogenic pressures were on average shown to have higher impacts on runoff in wetlandscapes in comparison to climate change. The pressures however showed relatively large variability between different wetlandscapes, which needs to be considered in mitigation strategies against wetland degradation and deterioration. Similarly, regarding wetlandscape ecohydrological characteristics, results indicated that there are variability between wetlandscapes of different sizes, where larger wetlandscapes showed features that can support ecosystem services to larger degree than small wetlandscapes. Large spatial variability in wetland ecohydrological characteristics was also seen within a wetlandscape. For instance, water storage dynamics and buffering capacity varied depending on the position of the wetland in the landscape. These differences in hydrological conditions were shown to result in different inundation dynamics between wetlands, which for instance also showed to impact insect community composition.Overall, this thesis shows that assessments of wetland ecosystem services need to be addressed using a wetlandscape approach, combined with actual on site hydrological measurements. The approach used in this thesis could help decrease uncertainties related to the impacts of hydro-climatic changes and anthropogenic pressures on wetlands and wetlandscapes, supporting location-specific wetland management strategies related to creation, restoration and sustainable use of wetlands and their ecosystems.