Format: ORAL

Estela Illa Bachs1,2, Iu Vilaseca Juan1, Nria Llaurad Nolla1, Nria Roca Pascual1

1 Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals. Facultat de Biologia. Universitat de Barcelona, Barcelona, Spain. 2 Institut de Recerca de la Biodiversitat (IRBio), Universitat de Barcelona (UB), Barcelona, Spain

Snowbeds are those environments in temperate high mountains that remain covered by snow until mid-summer, and where only a set of specialised species are able to thrive. Climate change represents a major threat for these ecosystems and species. The rising temperatures cause an earlier snowmelt, and snowbeds become then favourable environments for the more competitive species growing in the surrounding alpine grasslands. The way snowbed specialists respond to changing environmental conditions through their vegetative and reproductive performance may be crucial to face not only new abiotic stresses but also the higher competition exerted by grassland species. In 2017, we set four pairs of control and OTC (Open Top Chamber) plots in four Pyrenean study sites with presence of the dioecious dwarf shrub snowbed specialist Salix herbaceaL., with the aim to induce a moderate increase of temperatures on this species. In year 2021, we collected from 3 to 5 Salix herbaceas female ramets with mature fruits per plot, and we analysed a set of foliar and reproductive traits, among which leaf area, LDMC, SLA, viable seeds/fruit, total seeds/fruit or proportion of viable seeds. Preliminary results showed a site dependent trend towards a higher leaf productivity inside OTC, where we usually observed larger leaves with higher SLA and lower LDMC. Moreover, we also observed an increase of soil N in many of the OTC plots. Concerning reproductive traits, we found a trend towards a lower reproductive performance of Salix herbacea inside the OTC, with lower seed production and seed viability. Overall, the results suggest that increased temperatures have a fertilising effect in snowbeds, that enhance leaf productivity of Salix herbacea. However, the lower reproductive performance inside the OTC suggests that Salix herbacea may be approaching to its thermal fertility limit, which may pose a threat to its colonizing ability.