Effects of snowmelt timing on leaf traits, leaf production, and shoot growth of alpine plants: Comparisons along a snowmelt gradient in northern Sweden

Abstract

Effects of snow-melt timing on leaf traits (for five deciduous and five evergreen species), shoot growth, and leaf production (for five evergreen species) of tundra plants were studied along a snow-melt gradient in an alpine snowbed in northern Sweden. In deciduous plants, leaf life-span and leaf mass per area (LMA) decreased, and nitrogen concentration (leaf N) increased with decreasing growing season, whereas in evergreen plants, both leaf life-span and leaf N increased with decreasing growing season. By extending leaf life-span, evergreen plants are able to have a large leaf mass, which may contribute to maintain net annual carbon gain in short snow-free seasons. In two predominantly boreal evergreen species, Empetrum hermaphroditum and Vaccinium vitis-idaea, leaf life-span was negatively correlated with both annual leaf production and shoot growth, but there were no similar significant correlations for the other three, strictly arctic-alpine evergreen species (Cassiope tetragona, Loiseleuria procumbens, and Diapensia lapponica). Based on these results, we predict that extension of season length will decrease leaf N of both deciduous and evergreen species, and will accelerate leaf turnover of evergreen plants. Although annual leaf production and shoot growth of boreal species may increase with an extension of season length, they will remain unchanged in strictly arctic-alpine species.