Different dispersal abilities of plant species impact the future composition and distribution of biomes across the Arctic

Recent climate warming has been much faster in the Arctic than in the rest of the world, and is expected to accelerate in the future. These rapid changes will affect arctic biodiversity, threaten certain species and shift their distribution ranges. With a focus on dispersal abilities, we here aim to better understand the dynamics of plant species distributions over the next century, and how these changes may impact the composition and distribution of biomes across the terrestrial Arctic. We developed climate-driven species distribution models (SDM) to predict the emerging climate niches for 1174 plant species under different climate scenarios. The model was parameterized using field observations stored in the Global Biodiversity Information Facility database (GBIF) and temperature and bioclimatic variables from the CHELSA climate data set. Trait-based dispersal rates were assigned to each species according to Lososová et al. (2023) and were implemented and used to predict future habitat with a distance-based probability over time. Our results indicated that given the dispersal constraints, only 15 % of the emerging climate niche would be in reach for colonization of plant species until 2100. Characteristic “boreal forest”-biomes were predicted to gain area while the "tundra"-biome became squeezed between the “boreal forest”-biomes and the sea. The “Palearctic boreal forest”-biome was predicted to colonize more area while the "Nearctic boreal forest"-biome showed the largest spatial displacement to the north. The species composition of the vegetation biomes was predicted to change over time and habitat suitability declined overall. We find that the response of arctic plant species to climate change is not simply a straight migration towards the north but rather a complex interaction of different mechanisms leading to altered distribution ranges. The differences in species’ dispersal abilities could lead to compositional changes within the biomes, which can subsequently result in biome shifts from tundra to boreal forest. Extinction lag and establishment lag might substantially delay the predicted range shifts. For future studies, we recommend to include dispersal constraints as we could show that they substantially impact species distributions.