Atmospheric deposition and solute export in giant sequoia - mixed conifer watersheds in the Sierra Nevada, California

• Published in: Biogeochemistry 1991-03, Vol.12 (3), p.207-230
• Main Authors: Stohlgren, Thomas J., Melack, John M., Esperanza, Anne M., Parsons, David J.
• Format: Article
• Language: English
• Subjects: abies; Agronomy. Soil science and plant productions; bassin versant; Biological and medical sciences; california; californie; Coniferous forests; Creeks; cuencas hidrograficas; ecosistema; ecosysteme; ecosystems; Forest ecosystems; Forest soils; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Generalities. Analysis and diagnosis methods; lluvia; National parks; pinus; pluie; Precipitation; rain; sequoiadendron; Silicates; soil solution; Soil-plant relationships. Soil fertility. Fertilization. Amendments; soluciones del suelo; Solutes; solution du sol; Streams; Watersheds
• ISSN: 0168-2563; 1573-515X
• DOI: 10.1007/BF00002608

Atmospheric depostion and stream discharge and solutes were measured for three years (September 1984 - August 1987) in two mixed conifer watersheds in Sequoia National Park, in the southern Sierra Nevada of California. The Log Creek watershed (50 ha, 2067-2397 m elev.) is drained by a perennial stream, while Tharp's Creek watershed (13 ha, 2067-2255 m elev.) contains an intermittent stream. Dominant trees in the area include Abies concolor (white fir), Sequoiadendron giganteum (giant sequoia), A. magnifica (red fir), and Pinus lambertiana (sugar pine). Bedrock is predominantly granite and granodiorite, and the soils are mostly Pachic Xerumbrepts. Over the three year period, sulfate (SO42-), nitrate (NO3-), and chloride (Cl-) were the major anions in bulk precipitation with volume-weighted average concentrations of 12.6, 12.3 and 10.0 μeq/1, respectively. Annual inputs of NO3-N, NH4-N and SO4-S from wet deposition were about 60 to 75% of those reported from bulk deposition collectors. Discharge from the two watersheds occurs primarily during spring snowmelt. Solute exports from Log and Tharp's Creeks were dominated by HCO3-, Ca2+ and Na+, while H+, NO3-, NH4+ and PO43- outputs were relatively small. Solute concentrations were weakly correlated with instantaneous stream flow for all solutes ($\text{r}^{2}