Altitudinal patterns of floral morphologies in dry calcareous grasslands

A central goal in vegetation ecology is the identification of processes that influence species assemblage and distribution within a community. Among the wide variety of biotic interactions, plant-pollinator interactions are assumed to have a marked influence on plant communities assemblage and dynamics. The aim of this work was to verify if in dry grasslands there is a non random distribution of different blossom types along an altitudinal gradient, which may exert a selective pressure on both plants and insects, as well as on their mutualistic relationships. We sampled 85 plots in pre-alpine and hilly reliefs of the Veneto Region, finding that different blossom morphologies were patterned along the altitudinal gradient. Wind blossom type was dominant at low altitude while disk shaped flowers prevailed at high altitude. Our study revealed that altitude might affect species assemblage in dry grassland communities not only by selecting plant species according to their tolerance to different environmental conditions, but also according to their floral morphology, evoking the possibility of an indirect pollination filtering to occur.