Acid precipitation falls on vast areas of forested land, including most of the eastern deciduous forest of the United States. Forest productivity, ground-water quality, and surface waters might all be affected. To document and quantify ecosystem response to the onset of acid precipitation, simulated sulfuric acid (H2SO4) rain was applied to model forest plots of sugar maple (Acer saccharum) and red alder (Alnus rubra). One set of four plots (two alder and two maple) received a control rain constiting of a stock solution equilibrated with atmospheric CO2 to approximately pH5.7. Final results showed that a hardwood canopy and litter layer can alter the input of chemicals to the soil from acid rain.