In late October 2009 (i.e., the end of the second growing season
after planting) and January 2011 (i.e., after the third growing season
after planting), a composite sample of current year needles
was systematically collected from the five longleaf pine seedlings
(5–10 needles per seedling) selected for soil moisture/temperature
measurements in each subplot (three samples per main plot). We
collected needles after the growing season, when nutrient reallocation
fluxes are at a minimum (Dickson, 1989). Needles were dried
at 70 C and prepared for foliar nutrient analyses following protocols
of Clemson Agricultural Services Laboratory. Foliar nitrogen
(N) concentrations were determined using LECO FP528 Nitrogen
Combustion Analyzer (LECO Corporation, St. Joseph, MI). Foliar
phosphorus (P), potassium (K), calcium (Ca), and magnesium
(Mg) concentrations were analyzed using a Jobin Yvon Contained
Inductively Coupled Plasma Emission Spectrometer (ICP-ES, Horiba
Ltd., Edison, NJ).