Assessing tree migration potential: Growth deviations and range dynamics in eastern U.S. forests

Abstract

Understanding how tree species respond to climate change is essential for predicting future forest composition and ecosystem dynamics. This study evaluates the migration potential of tree species in the eastern United States by integrating growth residuals, absolute growth rate, and Importance Value (IV) as complementary indicators of species’ responses to environmental change. Growth residuals, which measure deviations from expected growth after accounting for tree size and environmental factors, provide insight into species’ recent responses to climate variability. Absolute growth rate reflects species productivity trends across latitudinal gradients, while IV serves as a historical baseline of species abundance and demographic stability. Using Random Forest modeling, we identified basal area, mean temperature, and mean precipitation as the most influential predictors of tree growth. We then applied Huisman-Olff-Fresco (HOF) models to assess latitudinal patterns in growth residuals, absolute growth rate, and IV. Our results revealed three major patterns: (1) species exhibiting northward growth residual peaks, suggesting poleward expansion potential; (2) species with southward growth residual peaks, indicating possible range contraction or climate limitations at northern edges; and (3) species with stable growth residuals, implying demographic inertia or localized climatic stability. Additionally, frequent mismatches between growth residuals and IV suggest that many species remain abundant in historical ranges despite shifting climatic suitability. While regeneration strategy is a key factor influencing species distributions, our findings suggest that it primarily affects IV rather than short-term growth responses. Wind-dispersed species, such as red maple and sugar maple, exhibited strong northward trends across all three metrics, whereas heavy-seeded species like sweetbay and slash pine had IV peaks farther south than their growth residuals, suggesting that past recruitment dynamics may lag behind recent growth patterns. These results highlight the need to consider both historical abundance and recent growth responses when evaluating migration potential. Our study provides empirical evidence that climate-driven range shifts in eastern U.S. tree species are highly species-specific, shaped by growth performance, demographic history, and recruitment dynamics. These findings underscore the complexity of tree migration and emphasize the importance of integrating multiple metrics to better assess species’ responses to climate change.