Briofite e piante vascolari in sorgenti delle Alpi Italiane: analisi della biodiversità a grande scala spaziale e meccanismi di distribuzione a piccola scala spaziale

This work at large spatial scale deal with bryophyte and vascular plant biodiversity in the springs of Trentino Province (Italy); at fine spatial scale it deal with several experimental investigations on the mechanisms of bryophytes spatial distribution. 86 springs located uniformly in the Trentino Province have been examined. 167 bryophyte species and 201 vascular plants were identified and this study represent the first accurate check list for these habitats in Trentino and also in Italy. Statistical classification on these environments was able to identify the main groups and even most threatened situation from conservation point of view. Statistical model elaborated to study bryophyte and vascular plant richness showed different patterns for the two groups of plants. Spatial distribution of several bryophyte species at fine spatial scale was experimentally studied investigating the hydrological niche breadth. Theoretical distance from water level was estimated using photosynthetic pigments as indicator of stress. In particular, aquatic species have a wide niche overlapped even though the tails of distribution were different in some species explaining to some extend the species coexistence. With the second experiment, positive and negative interactions among several bryophyte species were studied. In synthesis, this experiment confirmed the correctness of some theoretical models for the balance between competition and facilitation in relation to environmental conditions; moreover, it underlined the importance of natural climatic fluctuations in determining the weight of these interactions.