Management of longleaf pine ecosystems: can soil map units improve evaluations of soil change?This article is part of a larger document. View the larger document here.
Adjoining soil map units that vary in slope were evaluated to assess if soil properties differed sufficiently to impact analyses of soil change under longleaf pine (Pinus palustris) management. A Piedmont site, an Upper Coastal Plain site, and two Middle Coastal Plain sites in Georgia were sampled. All sites were dominated by an overstory of longleaf pine. A total of 24 profiles were collected to a depth of 200 cm with each site containing two or three map units and two or three profiles within each map unit. Use of visible/near-infrared (VNIR) spectroscopy was also incorporated as a rapid, field-based approach for analyzing soil properties (i.e., clay, carbon [C], and pHCaCl2) that can aid in quantifying soil variability across topographic gradients or dynamic
soil properties (DSP) over time. Results indicate that soil map unit phases capturing steepness of slope were not a valuable stratification variable in analyzing DSP under longleaf pine at these sites. Few significant differences were observed with slope steepness at any depth (0–200 cm) for percent clay, percent C, or pHCaCl2. Values ranged broadly across the sites and among depths. Percent clay ranged from <1 to >70 percent, percent C ranged from 0.01 to 3.78 percent, and pHCaCl2 ranged from 3.42 to 6.17. Visible/near-infrared calibrations for percent clay demonstrated predictive value (i.e., R2 = 0.72-0.96) while those for C (i.e., R2 = 0.55-0.73) and pHCaCl2 (i.e., R2 = 0.20-0.62) indicated some utility for field classification or monitoring of DSP under longleaf pine ecosystems.