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Résumé :
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Modelling and establishment of plant indicators of ecological status for semiarid Mediterranean saline wetlands In 1971 the international RAMSAR Convention on the Conservation of Wetlands and Waterfowl already began to encourage research on wetlands, referring to the need for better scientific information to properly assess the situation. More recently the European Water Framework Directive (WFD) provides the common principles that are needed to improve the protection of European waterbodies, qualitatively and quantitatively, and to protect the aquatic ecosystems and wetlands directly depending on them. This is the case of Mediterranean semiarid saline wetlands. However, the advanced degree of terrestrialization of these ecosystems and their high seasonality, make typical indicators of inland aquatic ecosystems not always applicable for their characterization, and therefore other indicator parameters should be included in their characterization, which are typical of the plant and animal species highly adapted to these unique environments. Likewise, particular ranges of values of indicator parameters should be established, thus indicating ecological quality levels in these ecosystems. In order to define indicators of the ecological status of these ecosystems, different functional aspects of them have been investigated, at watershed and wetland scale, and the relationships between them have been established. At the wetland scale our study has mainly focused on plant communities, while at the watershed scale land use has been mainly studied. The specific objectives of the study were: (1) the delineation of drainage basins affecting each wetland, as well as the historical mapping of land uses, (2) the analysis of historical changes of perennial plant taxa in the wetlands in relation to changes in land cover in their watersheds, (3) plant communities characterization and mapping through field sampling and remote sensing techniques and study of their relationship with the land cover at watershed scale and (4) spatio-dynamic modeling of the evolution of plant communities in the Marina del Carmolí wetland. We have selected 11 wetlands in the Region of Murcia: Cañada Brusca, Matalentisco, Sombrerico, Boquera Tabala, Lo Poyo, Marina del Carmolí, Marina Punta Galera, Ajauque, Derramadores, La Alcanara and Rasall. The methodology used was based on the application of various theoretical and practical aspects of ecology, combining fieldwork with cabinet. The indicator parameters and ecological processes that have been studied, as well as the methodological techniques followed were: (1) Identification and characterization of the study wetlands (GIS techniques, fieldtrips, bibliography), (2) qualitative and quantititative study of its plant communities (field sampling and mapping through remote sensing), (3) watershed and wetland plant communities modelling (GIS) and (4) historical mapping of land uses in the wetland watersheds through remote sensing. Through the study and statistical analysis of the relationships between biological and landscape indicators, their validity as ecological status indicators for these ecosystems has been demonstrated and various indices have been developed, as well as spatio-dynamic wetland modelling tools.
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