The snow and the willows: earlier spring snowmelt reduces performance in the low-lying alpine shrub Salix herbacea
Julia A. Wheeler, Andres J. Cortés, Janosch Sedlacek, Sophie Karrenberg, Mark van Kleunen, Sonja Wipf, Guenter Hoch, Oliver Bossdorf and Christian Rixen
Article first published online: 21 APR 2016 | DOI: 10.1111/1365-2745.12579
Our study indicates that phenology, fitness proxies and fungal/insect damage of the dwarf shrub Salix herbacea are strongly influenced by snowmelt timing, and that earlier spring snowmelt reduced performance in S. herbacea. The likely mechanisms for many of the observed patterns are related to adverse temperature conditions in the early growing season. Lower clonal (stem number) and sexual reproduction (reduced fruit set) under earlier snowmelt, in addition to increasing damage probability, will likely lead to lower fitness and poorer performance, particularly in shrubs growing in early-exposure microhabitats. Further, we saw few concurrent benefits of higher temperatures for S. herbacea, particularly as warming was associated with lower clonal growth. As growing seasons become warmer and longer in arctic and alpine tundra ecosystems, early snowmelt is a critical mechanism reducing fitness and performance in a widespread dwarf shrub and may ultimately reduce dwarf shrub communities in tundra biomes.