ALBERT

Notes: Abstract An evaluation of the influences of acidic deposition and forest development on nutrient cycling and conifer productivity at the Charles Lathrop Pack Demonstration Forest, near Warrensburg, New York, was made. This site has a known land use history and is the source of 60 years of soils and silviculture research. Soils were characterized by a nutritional imbalance and support conifer plantations that exhibited declining growth. Historical and contemporary evaluations of nutrient cycling in 47- to 57-yr-old red pine plantations provided no evidence that acidic deposition has had an adverse influence on nutrient cycling. Ap horizon pH decreased from 1949 to 1962 but remained the same from 1962 to 1985. In the B horizon, pH was stable from 1962 to 1985. Exchangeable potassium levels in the Ap horizon fluctuated but did not significantly change from 1949 to 1985: in the B horizon it increased during the period 1962 to 1985. Levels of potassium in the foliage of red pine in unfertilized plots increased from 1949 to 1985, paralleling increases in B horizon potassium levels during that period. There was no increase in cation leaching from the mineral soil that could be attributed to anthropogenic inputs of NO3 − and SO4 2− due to retention of N and S in this ecosystem. Soil solution K+ chemistry was similar between the 1960's and the 1980's. Mineral soil pH and base cation status were differentially influenced by tree species since 1930. In general, temporal and contemporary trends of mineral soil pH and base cation status of the soil and foliage indicated that forest development has been the dominant factor influencing nutrient cycling in these conifer plantations. While results of these studies do not conclusively preclude involvement of acidic deposition effects as part of a forest decline syndrome, they indicate the importance of recognizing and measuring natural variability in forest soil processes due to differential species effects and forest aggradation. Because these effects may have a greater impact on stand productivity than the effects of acidic deposition, they can confound interpretation of acidic deposition research if not clearly understood.