Linking physiological drought resistance traits to growth and mortality of three northeastern tree species.

This article investigates how seedlings of three northeastern U.S. tree species—red spruce (Picea rubens), paper birch (Betula papyrifera), and northern red oak (Quercus rubra)—respond physiologically and in growth to extreme drought, warming, and their combination. Using a controlled greenhouse experiment with drought (irrigated, 15-day, and 30-day) and warming (+3.5 °C) treatments, the study found that long drought severely reduced photosynthesis, water potential, growth, and survival of red spruce and paper birch seedlings, while northern red oak exhibited greater drought resistance and maintained growth. Warming alone had minor effects, and competition between seedlings had limited impact compared to drought stress. The findings suggest that climate extremes may disproportionately threaten drought-sensitive native species like red spruce and paper birch, potentially favoring more drought-tolerant species such as northern red oak, with implications for future forest community dynamics in the region.