Aboveground nutrients and merchantable wood volume across soil nutrient gradients in managed northern hardwood forests of New England, USA

Abstract Forest management typically focuses on assessments of aboveground structure and yield, often overlooking the belowground nutrient reservoirs that sustain long-term ecosystem function. While soil nutrient richness is known to influence forest productivity and resilience, the role of base cation availability in shaping aboveground nutrient dynamics and merchantable wood value remains poorly understood in glaciated hardwood forests. This study investigated how soil nutrient richness, tree size class, and tree genus influence aboveground nutrient concentrations, pools, and merchantable wood volume and value across three managed northern hardwood forests in Vermont and New Hampshire, USA, spanning Poor, Moderate, and Rich soil nutrient richness classes. We measured foliar and wood nutrient concentrations (Ca, Mg, K, P) and estimated biomass and timber value across 45 forest plots. Nutrient-rich soils supported the highest foliar and woody nutrient concentrations, particularly for Ca and P, whereas total aboveground nutrient pools were driven primarily by forest structure rather than soil fertility alone. Acer and Fraxinus dominated aboveground nutrient pools, with Fraxinus having the highest wood concentrations of Ca, Mg, K, and P among all genera. Poletimber trees contained the largest wood nutrient pools due to their high collective basal area. Contrary to expectations, merchantable wood volume did not increase with increasing soil nutrient richness, likely reflecting differences in stand age and composition, indicating that soil fertility assessments alone are not sufficient to predict timber yield or stand value. However, merchantable wood value varied across the richness gradient, with the Moderate Forest consistently yielding the highest simulated returns due to a high abundance of Acer. These findings highlight the importance of soil fertility in sustaining long-term forest productivity, and suggest that standard pre-harvest assessments of species composition and stand structure should be paired with soil fertility surveys to maintain economic value in nutrient-limited northern hardwood forests.