Functional Plant Traits and Species Assemblage in Pyrenean Snowbeds

In mid-latitude mountains, snowbeds often consist of small, scattered alpine belt units that host many plants of high biogeographic interest. Because most snowbed species are weak competitors, it is important to study the dissemination and persistence of their seeds to better understand their population dynamics. This study analyzed the snowbed flora of the Central Pyrenees using 11 morpho-functional traits, mostly related to seed function. The seeds of most plants found in snowbeds are small or very small, they have ovoid to elliptical shapes, and have no attributes related to dispersal. When only snowbed specialists (i.e., with a phytosociological optimum in snowbed habitats) are considered, three strategy groups become apparent: i) annuals or pauciennials producing abundant small seeds prone to accumulate in the soil; ii) chamaephytes or hemicryptophytes that produce anemochorous seeds; and iii) other perennials – mainly hemicryptophytes – with no specific seed traits. In the first two groups, the extant populations are maintained either by permanent soil seed banks or by means of vegetative persistence and dispersal. The lack of specific traits in the third group suggests that these plants could be more sensitive to direct competitive exclusion from non-chionophilous species under a changing climatic scenario in which snowbeds tend to disappear.