Germination and establishment of snowbed plants of the North-Eastern Calcareous Alps (Austria)

Climate change induced habitat loss and fragmentation. This will increase the importance of migration disproportionately for species restricted to small and well-defined habitat patches. This study focuses on the impact of vegetation cover along a snow melt gradient on germination and establishment of Achillea atrata, A. clusiana, Arabis caerulea and Gnaphalium hoppeanum. Additionally, we also quantified the effect of above- and below-ground allocation patterns on the probability of seedling recruitment. Seeds were sown, and seedlings pre-grown in a climate chamber were transplanted to a snowbed-complex on mt. Rax (Lower Austria/Styria). Germination from sown seeds was higher in plots with open vegetation. Neither biomass allocation nor site conditions had a statistically significant impact on seedling survival, but trends could be detected. Seedlings with reduced root growth showed lower survival rates for three species, Achillea atrata, A. clusiana, and Arabis caerulea. Seedlings transplanted to intermediate positions showed the lowest mortality, and dense vegetation led to a higher seedling survival than open vegetation. Our results indicate that competitive and facilitative effects of the surrounding vegetation on snowbed species may change along different phases of their life cycles. An increase in vegetation cover of alpine snowbeds will thus threaten the viability of these populations mostly by reducing the open sites necessary for their germination.