# Carbon Dynamics of _Pinus palustris_ Ecosystems Following Drought
## Materials and Methods  
### Study Sites  
The study was conducted at the Joseph Jones Ecological Research Center (JERC) in Southwestern Georgia, USA, from 22 October 2008 through 21 October 2015. The JJERC is an 11,000 ha reserve located within the Plains and Wiregrass Plains subsections of the Lower Coastal Plain and Flatwoods section. The center has extensive stands of second-growth longleaf pine, and has been managed with low intensity, dormant-season prescribed fires for the past \(\sim\)75 years [21]. The stands used for this study are approximately 90 years in age and were naturally regenerated. These stands have maintained their natural structure since they have been managed with single tree selection harvests using ecological forestry practices [29].  
We selected study sites with soils in two drainage classes falling on the ends of an edaphic gradient for longleaf pine-wiregrass ecosystems at the center: (i) moderately poorly drained; and (ii) excessively well drained [30]. The poorly drained sites occur on upland terraces with soils classified as Aquic Arenic Kandiudults. These soils are sandy loam over sandy clay loam or clay on nearly level slopes with a water holding capacity of 40 cm water m\({}^{-1}\) soil [21]. An argillic horizon is present within 50 cm of the soil surface. The excessively well-drained sites occur on upland sand ridges of undulating slopes of 3%-4% and have deep, sandy soils, with no argillic horizon, _i.e._, no significant accumulation of clay is found within 300 cm of the surface. These soils are Type Quartzipsamments with a water-holding capacity (in the upper 300 cm) of \(\sim\)18 cm water m\({}^{-1}\) of soil [21]. Hereafter, we refer to the moderately poorly drained site as mesic and excessively well-drained site as xeric.  
The mesic ecosystem is characterized by a single overstory of dominant longleaf pine. Xeric ecosystems are dominated by open stands of longleaf pine and scrub oaks, where the co-dominant oak, turkey oak (_Quercus laevis_ Walter), occurs in all the aboveground strata. Dense ground cover at all sites is dominated by the perennial grass, wiregrass (_Aristida stricta_ Michx.), with numerous species of other perennial grasses and forbs also present [31]. The sites used in this study have previously been described by the authors of [21; 23; 30; 32].  
Prior to the study, both sites were burned in winter 2007. During this study, both sites were burned in January 2009. The sites were on a two-year burn cycle and were both burned in late winter of 2011 and 2013. In 2015, the mesic site was burned in late winter, whereas the xeric site was burned in early spring. Each fire was set using backing fires on the downwind side of the management unit to move the fire away from the downwind fire-break. Strip head fires were then set perpendicular to the wind, starting on the downwind end of the unit and moving upwind. Fires were initiated \(\sim\)30-50 m apart depending on fuel patterns, local weather conditions, and fire behavior [33]. We limit our discussion of fire in this manuscript due to the short-duration, limited response these systems have shown to fire [20].