Climb forest, climb: diverse disperser communities are key to assist plants tracking climate change on altitudinal gradients

Abstract

Climate change is forcing species to shift their distribution ranges. Animal seed dispersers might be particularly important in assisting plants tracking suitable climates to higher elevations. However, this role is still poorly understood due to a lack of comprehensive multi-guild datasets along elevational gradients. We compiled seed dispersal networks for the five altitudinal vegetation belts of the Tenerife Island (0–3718 m above sea level) to explore how plant and animal species might facilitate the mutual colonisation of uphill habitats under climate change. The overall network comprised 283 distinct interactions between 73 plant and 27 animal species, with seed dispersers offering viable pathways for plants to colonise upper vegetation belts. A pivotal role is played by a lizard as island-level hub, while four birds and one introduced mammal (rabbit) are also important connectors between belts. Eleven plant species were empirically found to be actively dispersed to elevations beyond their current known range, with observed vertical dispersal distances largely surpassing those required to escape climate change. Furthermore, over half of the plants arriving at higher elevations were exotic. Functionally diverse disperser communities are crucial for enabling plants tracking climate change on mountains, but exotic plants might particularly benefit from this upward lift.