![](https://d3ilqtpdwi981i.cloudfront.net/osi7Doog_AaTonetkiOH9pwuotk=/425x550/smart/https://bepress-attached-resources.s3.amazonaws.com/uploads/49/91/be/4991be82-28d5-4743-89ce-dad80bb66961/thumbnail_9740569e-cda1-4351-a61d-b78a27c00afd.jpg)
- relative role,
- understory,
- overstory,
- carbon cycling,
- nitrogen cycling,
- southern Appalachian,
- spruce-fir forest
This study investigated aboveground pools and fluxes of biomass, carbon (C), and nitrogen (N) in the overstory and understory of a southern Appalachian red spruce (Picea rubens Sarg.) – Fraser fir (Abies fraseri (Pursh) Poir.) forest, following adelgid-induced fir mortality and spruce windthrow. Using fifty 20 m × 20 m plots, stratified by elevation (1700–1900 m), we estimated standing biomass and fluxes of all growth forms from periodic stand inventories (1998–2003), vegetation surveys, and existing or derived allometric equations. Total C and N pools and fluxes were calculated from plant- and tissue-specific C and N concentrations. Total aboveground biomass attained predisturbance values, ranging from 313 Mg·ha–1 at the lower elevations to 204 Mg·ha–1 at the upper elevations. Overstory biomass production (5650 kg·ha–1·year–1) and N uptake (11–15 kg·ha–1·year–1) exceeded earlier reported values, indicating forest recovery. Woody understory accounted for 3% of aboveground biomass, 10% of annual productivity, and 19% of total N uptake (~7 kg·ha–1·year–1). Herbaceous vegetation, which comprised only 1% of total biomass, took up 18–21 kg N·ha–1 annually, >50% of total ecosystem N uptake (37 kg·ha–1·year–1). This suggests that N-rich understory vegetation plays an important role in N cycling.