Modeling the distribution of Acadian vascular rare plant species under future climate scenarios

Understory vascular plant species play a key role in natural ecosystems by maintaining nutrient balances and providing both food for wildlife and non-wood forest products. However, some such species are facing potential extirpation due to human interventions such as forest harvesting practices, land use change, and climate change. Despite their ecological and societal importance, the influence of different environmental variables on the distribution of vascular plant communities remains unclear. This study evaluated how several Acadian understory rare plant species (categorized as S1-S2 species) in New Brunswick will respond to future climate scenarios. We used presence-only occurrence records of four S1-S2 rare plant species and eight bioclimatic variables to calibrate climate suitability models using maximum entropy algorithm (MaxEnt). The key bioclimatic predictor variables for the two S1 species (Canada Honewort and Furbish Lousewort) were maximum temperature of the warmest month and precipitation of the driest quarter. The predictor variables with significant contribution for the two S2 plant species were annual precipitation (35%) for Anticosti Aster and precipitation of wettest quarter (85.7%) for Parker’s Pipewort. Our models predicted that the two S1 plant species are likely to gain more suitable climate space by 2070, while the two S2 plant species are likely to lose suitable climate space and may face extirpation risk from New Brunswick. The difficulty of projecting rare plant species is very scarce occurrence data, but analyses such as ours can help indicate current locations and in-situ and ex-situ climate change refugia areas for use in biodiversity conservation planning.