Willow oak (Quercus phellos) seedling roots continue respiration and growth during fall and winter in a soil temperature-dependent manner.

This article investigates the effects of soil temperature on winter root growth and respiration in willow oak (Quercus phellos L.) seedlings, a key species in greentree reservoirs (GTRs) of bottomland hardwood forests. The study found that willow oak roots continue to grow and respire during winter at soil temperatures as low as 5 °C, with both root elongation and respiration rates decreasing as soil temperature declines, but without evidence of root dormancy or metabolic acclimation. Seedlings retained semi-persistent, photosynthetically active leaves through winter, suggesting that continued carbohydrate supply supports root activity despite shoot dormancy. Additionally, cooler soil temperatures accelerated leaf senescence, indicating a potential influence of belowground conditions on aboveground phenology. These findings imply that soil temperature is a primary driver of root activity in willow oak seedlings during winter and may affect their survival and management in GTRs.