Freshly collected Acerrubrum L. leaves from a regenerating forest stand at the Coweeta Hydrologic Laboratory, North Carolina, were washed with experimental acid rainfall (pH 4.6). Nutrient leaching rates from undamaged leaves were significant for SO42−, K+, Ca2+, and Mg2+, whereas NO3−-N was absorbed from rainfall. Significantly greater leaching of SO42−, K+, Ca2+, and Mg2+, and significantly greater absorption of NO3−-N and NH4+-N, occurred in artificially damaged leaves than in undamaged leaves. Comparisons between leaching transfers and foliar nutrient pools showed that base cation (K+, Ca2+, and Mg2+) leaching losses account for up to 25% of foliar pools, whereas absorption of NO3−-N and NH4+-N from precipitation can increase total foliar N by almost 2%. Projected growing season cation leaching losses (expressed as a percentage of foliar pools) from damaged leaves were in agreement with previously reported whole-canopy leaching fluxes based on analysis of throughfall at the field site. These results suggest that nutrient leaching losses from young, rapidly growing tree leaves are lower than previously published leaching fluxes for more mature forest stands.
Changing patterns of daily precipitation totals at the Coweeta Hydrologic Laboratory, North Carolina, USA
