The influence of stemflow on the distribution of sulfate-S around the base of two tree species

Stemflow Influence on the distribution of soil (NaH₂PO₄- extractable) sulfate and pH was evaluated over three size classes of red maple (Acer rubrum) and scarlet oak (Quercus coccinea) at two experimental watersheds In Tennessee which receive different yearly Inputs of sulfur from atmospheric sources. The soil profile around the base of red maple and scarlet oak was sampled by horizon at 25, 50, 100 and 200 cm from the stem along four transects originating at the stem base which were spaced 90° apart.

Soil extractable SO₄-S and pH were analyzed by horizon to determine the effect of site, tree species, tree size class within species, site by species Interaction, sampling transects and distance sampled within transects, on these parameters. Statistical analysis Indicated that stemflow was not a factor Influencing SO₄-S distribution around the base of red maple and scarlet oak. Species, however, had a strong effect on A1, B22 and B22 soil SO₄-S con centrations than A1 horizons beneath scarlet oak (24*0 μg*g^-1 vs 19.5 μg^-1, respectively). The B22 and B23 horizons beneath scarlet oaks had greater SO₄-S concentrations than corresponding horizons beneath red maple (79.0 μg*g^-1 vs. 46.0 μg*g^-1 and 107 μg*g^-1 vs 68.0 μg*g^-1 for scarlet oak and red maple In B22 and B23 horizons, respectively). Reasons for the greater SO₄-S concentration of B22 and B23 horizons are unclear but may relate to 1) the effect of canopy area on throughfall SO₄-S content, 2) differences In aboveground biomass S content of red maple and scarlet oak, 3) the nature and extent of stemflow movement along root surfaces and old root channels or 4) subtle variations in properties of soils beneath red maple vs scarlet oak.