Throughfall chemistry of an ecotonal forest on the edge of the great plains

Throughfall concentrations and fluxes were examined in an oak-hickory forest on the western ecotone of the eastern deciduous forest biome during 1989. Throughfall chemistry from event-based sampling of three stands was compared with the chemistry of incident precipitation. During the dormant season, only one of eight elements had significantly higher flux under the forest canopy relative to precipitation. During the growing season, six elements had significantly higher flux in throughfall relative to incident precipitation, and nitrogen had a significantly lower flux. Rates of dry deposition of pedogenically derived elements were high relative to forests further to the east, while rates of deposition of anthropogenically derived elements were low in comparison to these same forests. About 50% of the inorganic nitrogen in precipitation was taken up by the canopy, the highest value reported for an eastern deciduous forest. There were significant differences in throughfall chemistry among the three stands, possibly due to differences in canopy structure and (or) species composition. Multiple regression analysis of the throughfall patterns showed significant correlations of throughfall chemistry with the length of the antecedent dry period and rainfall quantity for all elements examined.