Elemental Cycling Response Of An Adirondack Subalpine Spruce-Fir Forest To Atmospheric And Environmental Change

Patterns and trends in forest elemental cycling can become more apparent in the presence of atmospheric perturbations. High-elevation forests of the northeastem United States have received large amounts of atmospheric deposition of pollutants, which have altered natural elemental cycling and retention rates in a variety of ways. This study examined atmospheric deposition of nitrogen, sulfur and base cations, and their interactions in a high-elevation forest on Whiteface Mountain, New York. Eight years of elemental cycling data (1 986- 1993) have shown that at our main study site (1 050-m elevation), atmospheric deposition of N was approximately 16.7 kg N ha-' yfl, with 32 percent contributed by cloud water. Atmospheric deposition of S was 16.3 kg S ha-' yr-', with 37 percent contributed by cloud water. Total atmospheric inputs of nitrogen and sulfur to the forest canopy increased by a factor of four and five, respectively, over the elevational range of 600 to 1275 my largely due to the increased importance of cloud water deposition at high elevations. At 1050-m elevation, analyses of total ecosystem inventories and cycling revealed that nitrogen and potassium are conserved or retained in the ecosystem while sulfur, calcium and magnesium show losses in a relatively undisturbed spruce-fir-birch ecosystem.