Phenology and seed setting success of snowbed plant species in contrasting snowmelt regimes in the Central Pyrenees

Plant growth and performance in snowbed communities are strongly influenced by the length of the growing period remaining after the snowmelt date. Under the scenario of climate change, studying the phenological responses of snowbed species to variations in snowmelt date might be crucial to understand their ability to adapt and survive under changing conditions. We studied 13 plant species from contrasting biological and ecological groups (i.e. ‘snowbed specialists’, ‘preferential species’ and ‘generalist species’) growing in four snowbed plots with siliceous substrates in the Central Pyrenees. These species were monitored for two consecutive years and in two different microsites, namely the central part and the peripheral part of each snowbed plot. We characterised their phenological cycle and length and their success in seed setting, measured as the number of individuals succeeding in dispersing their seeds.Phenology and cycle length did not differ greatly between locations for any of the species, but their success in setting seeds was variable. We did not find substantial differences in species’ cycle length under varying snowmelt regimes (neither between years nor between microsites); this lack of differences was more evident for snowbed specialists. Moreover, this group showed shorter cycles and less ability to modify their phenology with varying snowmelt regimes than generalist species and some of the preferential species. These two latter groups showed a trend towards reduced success in setting seeds with retarded snowmelt, but the plant community structure exerted a complementary effect on seed setting which in some cases was even greater than snowmelt date. The ability to produce and disperse seeds seems to be a less conservative feature than cycle length in snowbed plants. Thus, their adaptation to future climate changes might take place as a result of variations in their reproductive performance rather than in the modification of their phenological cycle. In addition, shifts in plant community composition as a result of environmental changes might be of special importance in the behaviour of these species.