Abstract ID: 3.11399 | Accepted as Talk | Requested as: Talk | TBA | TBA

Species are shifting their ranges to higher elevations in mountains in response to climate warming. But there is large variation in the magnitude of range shifts, and on average range shifts are much slower than what would be required for them to track the rate of climate warming. To understand the mechanisms explaining range shift lags, we transplanted ten lowland plants to a site above their current elevation limit in the eastern Swiss Alps, with or without the existing vegetation, and with or without artificial warming using open-top chambers. We tracked individual level vital rates of these species across three growing seasons to construct integral projection models (IPMs) to predict population growth rates in the different experimental treatments. All species were predicted to successfully establish above their current elevation limit when the existing vegetation was removed, indicating that the high elevation site is within the climate niche of the species. Seven of the ten species were also predicted to successfully establish, or persist, above their current range edge in the face of interactions with the existing vegetation, and without supplementary warming. This suggests that the absence of these species at higher elevations today can be explained by dispersal limitation. While the remaining three species might also be dispersal limited, their absense from the high elevation sites can be explained by interactions with the resident vegetation, highlighting the potential for competition to constrain range expansion in response to climate change. We conclude that even when dispersal distances between species’ current distribution limits and newly suitable habitat are very small, as will often be the case in mountains, range shift lags can still be caused by dispersal limitation. Future work should therefore focus on quantifying dispersal rates of species along elevation gradients to determine which species may be able to track changing climate. However, our work also implies that even currently widespread species might not be able to keep pace with changing climate, and so measures such as assisted migration might be required to ensure their longer-term survival.