Models reveal shifting distribution of climatic suitability for pawpaw ( Asimina triloba [L.] Dunal) cultivation under future climate change scenarios

The pawpaw (Asimina triloba [L.] Dunal) is a deciduous tree notable for its large edible fruit. Native to the eastern US and Canada, it has earned attention as a horticultural commodity and focus of scientific inquiry. However, few studies have modeled its potential future distribution under climate change. This study predicted the current and future potential distribution for pawpaw in North America and globally, with a focus on understanding future climatic suitability for fruit cultivation. This study first modeled suitability via the Maximum Entropy (MaxEnt) method by relating climate predictors with different datasets on pawpaw distribution, including nursery locations growing pawpaw. It also trained a boosted regression tree (BRT) model to estimate where sufficient heat accumulation for fruit ripening would occur. The models were applied to two future times (2041-2060 and 2081-2100), four emissions scenarios (SSP126, SSP245, SSP370, and SSP585), and climate projections from three climate models. Using nursery locations, the MaxEnt model yielded a mean area-underthe-curve statistic of 0.978 (standard deviation = 0.009) using 10-fold cross-validation, indicating strong predictive performance. The model suggested optimal conditions for pawpaw at these values: -4 degrees C for minimum temperature of coldest month, 26 degrees C for maximum temperature of warmest month, 88 cm for annual precipitation, and 0 % for precipitation seasonality. Models suggested shifting suitable climate conditions and accompanying increases in heat accumulation for fruit ripening. Northern America, Eastern Europe, and Northern Europe were predicted to have higher and increasing suitability; Western Europe, Southern Europe, and Eastern Asia were predicted to have higher but decreasing suitability. Little uncertainty existed due to collinearity shift or dissimilarity between current and future climate, but more uncertainty existed when predictions were based on differing climate model projections. This study provides insight into the pawpaw's potential response to climate change, and guidance on future locations for cultivation.