Shrinking horizons: Climate-induced range shifts and conservation status of hickory trees (Carya Nutt.)

Abstract

Understanding the intricate interplay between the geographic distributions of species and the dynamics of environmental factors is crucial for effective biodiversity management. Crop wild relatives are important resources for the improvement of cultivated plants. However, our understanding of how these species might respond to future climatic changes and their implications for conservation remains incomplete. In this study, we focus on the ecologically and economically significant hickory trees to address this knowledge gap. We employed the Biomod2 ensemble model to predict the potential distributions of 12 North American and five East Asian Carya species based on 13,643 occurrence points and 26 environmental variables. We analyzed the distribution range dynamics of hickory trees across the past, present, and future emission scenarios (2090; SSP126 and SSP585), assessed their conservation status, and conducted a preliminary threat assessment. Our results indicate that most Carya species expanded their habitat range from the Last Glacial Maximum to the present, with substantial contraction projected under both future scenarios. A northward migration shift to high elevations was observed for most species from the LGM to the future. Sixteen species were categorized as “medium priority” for further conservation action, and only one (C. tonkinensis) as “high priority”. Preliminary threat assessment classified one species (C. luana) as critically endangered, eight endangered, four vulnerable, and five as least concern. This study underscores the potential effects of climate change on the distribution of Carya species, providing crucial insights for their conservation and highlighting the broader impacts of climate change on crop wild relatives.