Soil Chemical Changes On Two Forested Watersheds with Time and Acidification Treatment.

Forest soil chemistry remains one of the least understood components of most ecosystem studies.   In this paper, exchangeable soil nutrient concentrations on two forested watersheds on the Fernow Experimental Forest in West Virginia are evaluated over time   These two gaged watersheds , both containing stands of deciduous Appalachian hardwoods, form the backbone of the Fernow Watershed Acidification Study,  which was initiated in 1989.  Ammonium sulfate fertilizer has been applied to one of these watersheds  at a rate of 35.5 kg N/ ha and 40.5 kg S/ ha, since 1989.  The second watershed, which supports an older stand (~100 years old) of mixed hardwoods, serves as the reference watershed.   Soils were sampled in 1994, 2002, and in 2010, and analyzed for chemical constituents.  Significant changes in soil chemical properties were not detected after 12 years of treatment, and changes in soil chemistry at 21 years are also ambiguous.  We discuss the hypotheses related to soil acidification and evaluate them in light of the long-term data. Ancillary data on foliar nutrients and growth rates of trees are also described.