Das Projekt "Environmental Changes at the Ecocline between Subalpine and Alpine Vegetation Belts: Reaction of the Vegetation Cover^Changements environnementaux et modification de l'ecocline subalpin-alpin: reaction de la couverture vegetale (FRA)" wird vom Umweltbundesamt gefördert und von Ville de Geneve, Departement municipal des affaires culturelles, Conservatoire et Jardin botaniques durchgeführt. What will be the rapidity of the answer of plants considering the mechanisms of inertia (buffer effect of phytocoenoses, competition, physiological plasticity)? - Will the response be correlated and be directly proportional to the observed climatic changes? - Will all the plant communities be modified simultaneously or will some of them perdure for some while? - Will the different parts of the plant communities (synusiae) react simultaneously or differentially? - How is the transformation of the ecocline going to happen (progressively, by salutation, catastrophically)? The aim of the project is to measure the qualitative and quantitative response of the vegetation to modifications in environmental parameters, especially climatic ones. The vegetation cover is studied at all levels of spatial organisation, from the synusia to complexes of phytocoenoses. Two transects about 2 km wide were delimited on siliceous rock in the Valais: Val d'Arpette, Orsieres (1700-2800 m) and Belalp, Naters (1900-2800 m). 230 phytocoenological releves and 1128 synusial releves were performed and 22 permanent plots were established. The distribution of the flora is analysed in altitudinal sections of 100 m. Presently, 298 species of vascular plants are known for Val d'Arpette and 339 for Belalp. Beside the flora and vegetation, the phenology of selected species (e.g. Arolla Pine, prostrated Mountain Pine, Green Alder, Rhododendron) is being also studied in relation to meso- and microclimate, especially temperature. 31 phenological permanent plots were established and 257 phenological releves were performed. Microclimatic measurements of temperature were performed with the Palmann method of sugar inversion (500 blades) and direct measurement with 3 data loggers Grant Squirrel. In order to assess the qualitative and quantitative impact of predicted climatic changes on alpine vegetation, the project intends to elaborate a predictive model, in collaboration with four other projects (soils, bryophytes, genetical polymorphism of selected species, and modeling of plant distribution) to evaluate the potential modifications on the vegetation at several levels of integration (synusiae, plant communities, landscape), and the rapidity of those modifications. In addition, a long-term monitoring of the vegetation is established. The study of the sub alpine/alpine ecocline is carried on at two separate transects (1700-2800 m; 1900-2900 m) on siliceous rocks in the Valais with vegetation types analyses, structural analyses of alpha-, beta-, altitudinal plant diversity, vegetation mapping, permanent plots. In addition, there are phenological observations and investigations on the reproductive biology of key species linked with micro- and mesoclimate measurements.