Major-element cycling in a high-elevation Adirondack forest: Patterns and changes, 1986-1996

High-elevation forests in the northeastern United States have received larg e amounts of atmospheric deposition of pollutants that may alter natural el ement cycling and retention rates in a variety of ways. This study examined atmospheric deposition of N, S, and base cations (Ca2+, Mg2+, K+, Na+), an d their impact on element cycling, in a high-elevation forest on Whiteface Mountain, New York, USA. Ten years of element cycling data (1986-1995) show ed that at our study site (1050-m elevation) precipitation and cloud water contributed most of the atmospheric deposition relative to dry deposition. Input-output budgets revealed a net retention of N in this forest. Tn contr ast, annual variations in outputs of K+ were roughly balanced by atmospheri c inputs. Potassium output seemed to be strongly related to and dependent o n K+ inputs. There was a net loss of Ca2+, Mg2+, and SO42- from the site. C alcium and SO42- outputs were related to one another and to water inputs to the forest. Net loss of 2.9 kg S.ha(-1).yr(-1) was likely supplied by the large mineral soil S pool. The difference between atmospheric input and eco system export of 7.4 kg Ca.ha(-1).yr(-1) may or may not be sustainable, dep ending on replacement by mineral weathering. The dominance of inorganic N s pecies in all solutions except O-horizon leachate supports the idea that th e forest is heavily impacted by N deposition. However, the decrease in NO3- export from the forest observed during the study and the continued accumul ation of N in vegetation suggest that N saturation has not yet occurred.