Influence of nitrogen deposition on Southern Appalachian deciduous forests

SUMMARY: The declining health of high elevation red spruce (Picea rubens) and Fraser fir (Abies fraseri) in the Southern Appalachian region has long been linked to nitrogen deposition. Recently, nitrogen deposition has also been proposed as a source of negative health impacts in lower elevation deciduous forests. Researchers have established 46 plots on six sites in North Carolina and Virginia dominated by American beech (Fagus grandifolia), sugar maple (Acer rubrum), and yellow birch (Betula allegeniensis), where they will evaluate several response variables across a nitrogen deposition gradient, including annual basal area growth; foliage %N, Al, P, K, Mg and Ca; forest floor %N, Mg, C and pH; and potential net nitrification and nitrogen mineralization rates. The objectives of this study are to correlate the response of tree species' basal area growth rates, foliar chemistry, and nitrogen cycling to a gradient of nitrogen deposition in the Southern Appalachians and to determine if any of these relationships could be characteristic of declining forest health.

STATUS: Completed

EFETAC'S ROLE: Although the “on the ground” tasks associated with this project have been completed, EFETAC scientists continue to provide technical and research expertise to USDA Forest Service staff and other agency and university researchers on the impacts of nitrogen deposition on forested ecosystems in the southeastern U.S.  Therefore, EFETAC is still providing minimal funds (via salary and meeting costs) to this project.

PROGRESS:

Johnny Boggs, Steve McNulty, Michael Gavazzi, and Jennifer Moore Myers. 2005. Tree growth, foliar chemistry, and nitrogen cycling across a nitrogen deposition gradient in southern Appalachian deciduous forests. Canadian Journal of Forest Research. 35: 1901-1913. (PDF)

CONTACT: Johnny Boggs, EFETAC Biological Scientist, johnny.boggs@usda.gov or 919-549-4060

Updated May 2010