Changes in temperature and precipitation (as snowfall) will affect the start and duration of the growing season at high elevation and shift phenology and affect growth of alpine species. Disentangling the complex interactions of plastic and genetic responses in phenology to climate is key to understand species responses to future climate changes, but to date, few studies have explicitly addressed these interactions. Here we mimicked future climate change projections for western Norway by performed a transplant experiment with individuals of Ranunculus acrisalong regional-scale temperature and precipitation (and snowmelt) gradients. Plants were transplanted to warmer, wetter and warmer & wetter sites, and we recorded their phenological development and growth over one growing season.
The phenology of the transplanted R. acris individuals was affected by both phenotypic plasticity and genetic differences between populations of different origin, while growth showed only plastic responses. Phenology was accelerated when transplanted to warmer, wetter and warmer & wetter sites, showing plastic responses to the different environments. Also, plants from late snowmelt sites (colder and wetter habitats) showed earlier onset of phenological development and faster phenological transition compared to plants from warmer and drier sites when grown in common gardens. This suggests that shorter growing season due to later snowmelt exerts a strong selection for earlier phenological development. These findings imply that populations of widespread species may be more vulnerable to climate change than inferred from their distribution alone. Climate change impacts are complex – to project species fates under future climate we need to consider different aspects of climate change, such as temperature and precipitation change, and also both direct climate impacts on plants and indirect impacts through e.g., changes in seasonality.