Precipitation and throughfall chemistry in Pinuscontorta ssp. latifolia ecosystems, southeastern Wyoming

Abstract

Precipitation and throughfall quantity and chemistry were measured in several Pinuscontorta ssp. latifolia ecosystems in southeastern Wyoming. Bulk deposition (open collector) was somewhat enriched chemically in comparison with wetfall (shielded collector), suggestive of dry deposition. With the exception of low S concentrations, atmospheric chemistry was comparable to other continental locations in North America. Concentrations of most solutes were much higher in canopy throughfall than rainfall. Canopy evaporation accounted for a 27% increase of dissolved solids in throughfall, the remaining differences being attributed to canopy leaching and washing of dryfall. Throughfall was most enriched in K⁺, Mg²⁺, and organic anions, indicating the importance of canopy leaching. Very high spatial variation was observed within the forests, precluding the detection of annual or site differences in throughfall chemistry. Our estimates of dry deposition to the lodgepole pine ecosystem were lower than for more polluted regions of eastern North America. Except for SO₄²⁻, wetfall supplied larger amounts of the major elements than dry deposition. Canopy leaching was a major flux pathway in these ecosystems, particularly for K⁺, Mg²⁺, and SO₄²⁻.