Forests growing on periodically flooded or waterlogged soils are land-water interfaces and regulators of water supply, mitigating floods and improving water quality [1]. In Southern Europe, wetland forests occur in the transition between temperate and semiarid regions, near the limit of their range of distribution [2]. As a result, they seem to be more sensitive to global changes than ecosystems located in their biogeographical optimum [3]. This high susceptibility has two critical implications. First, due to their responsiveness to environmental change [3] wetland forests can be used as sentinel ecosystems to detect symptoms of global changes. Second, their intrinsic fragility and scarce area covered [2], as well as their inherent ecological value [1] makes them target ecosystems for protection measures. Doñana National Park represents the southernmost location of wetland forests in the Iberian Peninsula and includes one of the largest and best preserved examples of this type of ecosystems [2]. The objectives of the proposal are identifying sentinel indicators of climatic change through the study of the spatial and temporal variation trends in the community structure and the ecophysiological responses of trees occurring in Doñana wetland forests. In addition, the adequate understanding on physiological and genetic basis of wetland forest ecosystem functioning will provide scientific-based tools for their conservation and restoration. The proposal involves the establishment of a multiscale monitoring program of Doñana wetland forests, including a community-level and an individual-level research. The community-level monitoring includes a continuation of the work started with an ECODOCA project in 2004, focused on the floristic composition and structure of the wetland forest community. Additionally, the establishment of permanent exclosure and control plots will allow the study of vegetation dynamics with and without the effects of herbivory by deer. The individual-level monitoring involves the selection of wetland trees for the study of ecophysiological responses to ecological change. The end-point of the monitoring is the development of the key-stone parameters needed for the sustainability of wetland forests ecological integrity in
the long term, such parameters derived from: floristic composition, age structure, genetic diversity, gender distribution in dioecious species, physiological status, and water use.