Patterns of plant traits in Pyrenean alpine vegetation

Here we studied the adaptation of plant communities to environment in the alpine belt of the Catalan Pyrenees through comparative analysis of plant traits. The starting point consisted of about 800 phytocoenological relevés from the Banc de Dades de Biodiversitat de Catalunya, which corresponded to 47 communities (associations and subassociations) and included 683 taxa. Eleven attributes were examined in each community. Some of these traits are directly referred to the community level (averages of cover, species richness or diversity of life forms) and others to species level, but expressed as the relative cover in the communities (percentages of life forms, succulence, evergreeness, woodiness, lateral spread ability, dissemination type). Alpine landscape is mainly made up of hemicryptophytes, of which graminoids dominate in terms of cover and non-graminoids in species number. Strong persistence via plurennial stocks or dense turfs, entire above-ground renewal over winter, lateral spreading over short distances and generalistic diaspore dissemination complete the main attributes of the High Pyrenees and most alpine floras. Nevertheless, considerable percentages of particular plant types (like therophytes, various kinds of chamaephytes, succulents, evergreens and berry-producers) give a highly diversified alpine belt.On the basis of the attributes, we performed a fuzzy multivariate classification of plant communities, which gave seven main vegetation groups, and five subgroups in the largest category (pastures). Most of the groups coincided with high-level syntaxa (classes, orders) and corresponded to the main habitats of the alpine belt, defined in terms of topography and related soil and microclimate descriptors. With respect to the spectrum of attributes of the whole alpine flora, the most differentiated groups of communities corresponded to several main habitats, all of which associated with stress conditions (scarcity of soil, unfertile or waterlogged substrata). These plant communities tend to be species-poor and show relatively high percentages of particular types. Groups less differentiated from the global spectrum included mainly richer communities with more shared dominances, and correspond to more balanced environments.