Temporal Patterns in Beech Forest Soil Solutions: Field and Model Results Compared
Johnson DW. 1995. Temporal Patterns in Beech Forest Soil Solutions: Field and Model Results Compared. Soil Science Society of America Journal. 59(6):1732-1740
ABSTRACT: The applicability of cation exchange equations and the Nutrient Cycling Model (NuCM) to a beech (Fagus grandifolia Ehrh.) forest soil in the Great Smoky Mountains, North Carolina, was tested by examining temporal variations in soil solution chemical composition. Both field data and NuCM output implied that short-term, local variations in exchangeable Ca2+ and Al3+ occurred, causing non-ideal plots of pAl vs. pCa in soil solution. Thus, plots of pCa vs. pAl, with their inherent assumptions of constant exchangeable cations, do not provide an adequate test of the applicability of cation exchange equations to field conditions. A large NO3− pulse caused sequential peaks in soil solution Mg2+, Ca2+, and Al3+, which became more separated with soil depth. The NuCM model did not reproduce this pattern, showing instead simultaneous peaks of all cations in response to NO3− pulses. As a consequence, NuCM underestimated peak Al/Ca ratios. The disparity was probably due to the coarse scale at which NuCM and models like it represent the soil. A chromatographic model may be more appropriate for this time scale.
- Type
- Journal Article
- Authors
- Johnson, Dale
- Units
- GRSM
- Keywords
- acid deposition, aluminum, American beech, APHN, Appalachian Highlands Network, calcium, Clingmans Dome, Fagus grandifolia, Great Smoky Mountains National Park, GRSM, GRSM-00623, magnesium, SER, soils, Southeast Region