Effects of climate change on shrub growth in high mountains:
With the rapid warming of the alpine zone shrub growth has increased and shrubs have expanded. Satellite proxies for vegetation biomass have shown greening trends in recent decades over large parts of the tundra biome, which have been linked to shrub growth chronologies, and summer temperatures in some areas. As shrubs are expanding both north- and upwards and are infilling from their present locations, energy, e.g. through a decrease in albedo, and mass dynamics are changed, with possible drastic feedbacks to climate and ecosystem processes. Both deciduous and evergreen species have been expanding, which may have partly opposite consequences regarding feedbacks as they differ in their litter quality, reduction by herbivory, and associated mycorrhizal fungi. Summer warming is most likely the main driver of shrub growth, but this may be controlled by soil moisture availability. Extreme winter warming and associated rain-on-snow events, as well as late frost events after earlier snow-free dates may limit shrub expansion. Their effects remain poorly studied, as are the climatic drivers of shrub recruitment, which may depend on site characteristics such as snow depth, and shrub growth form.