Managing Global Resources for a Secure Future

Eastern hemlock (Tsuga canadensis) is a shade-tolerant, evergreen tree that suffered widespread mortality in the southern Appalachian Mountains due to infestation by hemlock woolly adelgid (Adelges tsugae), an invasive exotic insect. Hemlock loss has led to altered forest structure, soil processes, and hydrologic regimes. Recovery of these riparian forests, (e.g., tree regeneration and N cycling processes) has been constrained by the presence of Rosebay rhododendron (Rhododendron maximum), an evergreen shrub, which forms a deep, recalcitrant O-horizon. We explored site restoration methods designed to accelerate N cycling by using prescribed fire with and without cutting rhododendron (cut + burn, cut only, burn only, and reference). Treatments were implemented in spring–summer 2015. We measured microclimate and N cycling responses one year before treatment and for two years after treatment. After treatment, soil temperature and soil moisture increased on the cut + burn and cut only plots. While soil N transformations did not change on any of the treated plots, we found increased soil solution inorganic N in the cut + burn plots.