| The soil and soil solution chemistry of the rooting zone of a high elevation spruce-fir ecosystem (Clingman's Dome, Great Smoky Mountains National Park, N.C.) was characterized and the role that acidic deposition may be having in the apparent decline of red spruce at this site was evaluated.;Soil solution samples following rainfall events were collected over three years using microporous hollow fiber samplers. Average mumolar concentrations were Mg 10, Ca 14, Al 26, H+ 142 (pH 3.94), NO3 41, SO4 72, and total organic carbon (TOC) 1254. For 80% of the samples the Ca/Al molar ratio was <1 (60% for (Ca + Mg)/Al). Soil solution concentrations of H+, Al, and Ca were positively correlated indicating that solution concentrations are controlled in a consistent manner over time, however, the relationships vary from location to location.;Soil samples were extracted with 1 M NH4Cl and 1 M HCL. NH 4Cl extractable Ca and Mg were positively correlated with soil %C. HCl extractable Al, Mg, Fe, Si and TOC were negatively correlated with soil %C and positively correlated with particle density (except Al). Soil organic matter (SOM) is apparently the major source of exchangeable Ca and Mg. HCl extractable Mg, Fe and Si may originate from mineral sources and Ha extractable Al is apparently associated with HCl extractable SOM.;Soil solution Ca and Fe were correlated to NH4Cl extractable Ca and Fe and solution H+ was correlated to soil %C.;Columns of soil material from the rooting zone were subject to differing concentrations and input rates of artificial acidic deposition while at 10°C (50°F). The amount of precipitation and the concentration of the input solutions were both determining factors of soil solution concentrations.;Acidic deposition may exacerbate low Ca/Al ratios by increasing Al solution concentrations. Low solution concentrations of Mg and Ca, coupled with the prevalence of total Ca/Al and (Ca + Mg)/Al ratios less than one, may contribute to nutritional deficiencies of Ca and Mg in red spruce. |
