## 2 Materials and Methods
### Site Descriptions
#### 2.2.2 Jerc-Rd  
Jones Ecological Research Center at Ichauway is located near Newton, Georgia, USA (31\({}^{\circ}\) N, 84\({}^{\circ}\) W, 25-200 m elevation). A map of the JERC-RD flux tower with landcover classes is shown in Figure 4. The site falls within the East Gulf Coastal Plain and consists of flat to rolling land sloping to the southwest. The region is characterized by a humid subtropical climate with temperatures ranging from 5-34 \({}^{\circ}\)C and precipitation averaging 132 cm year\({}^{-1}\). The overall site is 12,000 ha in area, 7500 ha of which are forested [123]. The site also exists within a tributary drainage basin that eventually empties into the Flint River. Soils here are underlain by karst Ocala limestone and mostly Typic Quartzipsamments, with sporadic Grossarenic and Aquic Arenic Paleudults [124]. Soils here often lack well-developed organic horizons [123; 124; 125]. \begin{table}
\begin{tabular}{l c} \hline \hline
**Species** & **Count** \\ \hline ACPE & 56 \\ ACRU & 4924 \\ BEAL & 729 \\ BELE & 239 \\ BEPO & 116 \\ CADE & 1 \\ FAGR & 277 \\ FRAM & 258 \\ ILVE & 86 \\ PIGL & 397 \\ PIRE & 638 \\ PIST & 582 \\ PRSE & 270 \\ QURU & 2485 \\ QUVE & 247 \\ TSCA & 1926 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: HF-EMS species abundance for the 34 tower plots in 2002. Forests here are mostly second-growth, approximately 65-95 years in age. Long-leaf pine (_Pinus palustris_ Mill.) dominates the overstory, while the understory is comprised primarily of wiregrass (_Aristida stricta_ Michx.) and secondarily of shrubs, legumes, forbs, immature hardwoods, and regenerating long-leaf pine forests [126]. Prescribed fire is a regular component of management here, with stands often burned at regular 1-5 year intervals [123]. This has promoted wiregrass and legumes in the understory, while reducing the number of hardwoods [123]. The RD EC flux tower is contained within the mesic/intermediate sector. This site consists of only four primary tree species from two genera: Long-leaf pine (_Pinus palustris_), water oak (_Quercus nigra_ L.), southern live oak (_Quercus virginiana_ Mill. ), and bluejack oak (_Quercus incana_ [PERSON]). Measurements for the RD tower are available for the 2008-2013 time period. Summary statistics for the RD tower site for the year 2008 are provided in Table 3.  
A table of observed species abundances for the year 2009 are provided in Table 4.  
Figure 4: Jones Ecological Research Center (JERC) RD flux tower and landcover classes. \begin{table}
\begin{tabular}{l c c c c c c c} \hline \hline
**Statistic** & **N** & **Mean** & **St. Dev.** & **Min** & **Pctl(25)** & **Pctl(75)** & **Max** \\ \hline DBH\({}_{Mean}\) & 4 & 31.498 & 2.870 & 27.426 & 30.530 & 33.392 & 33.719 \\ DBH\({}_{St.Dev.}\) & 4 & 12.733 & 2.737 & 10.525 & 11.293 & 13.285 & 16.714 \\ BA & 4 & 17.604 & 1.662 & 15.764 & 16.780 & 18.273 & 19.756 \\ Stocking & 4 & 201.000 & 60.871 & 164 & 170 & 205 & 292 \\ QMD & 4 & 33.968 & 3.374 & 29.350 & 32.665 & 35.987 & 37.152 \\ SDI & 4 & 310.965 & 39.514 & 278.001 & 291.255 & 318.514 & 368.254 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: JERC-RD forest inventory summary for the four tower plots in 2009; DBH = depth at breast height (cm); BA = basal area per hectare (m\({}^{2}\)); Stocking = n\({}_{trees}\) per hectare; QMD = quadratic mean diameter (cm); SDI = [PERSON]’s stand density index [121]. Two recent studies [127; 128] indicate that the mesic sector of this subtropical pine savanna functions as a moderate carbon sink (NEE = \(-0.83\) Mg C ha\({}^{-1}\) year\({}^{-1}\); \(-1.17\) Mg C ha\({}^{-1}\) year\({}^{-1}\)), reduced to near-neutral uptake during the 2011 drought (NEE = \(-0.17\) Mg C ha\({}^{-1}\) year\({}^{-1}\)), and is a carbon source when prescribed burning is taken into account. NEE typically recovered to pre-fire rates within 30-60 days. The mechanisms behind soil respiration rates here again appear to be complex, site-specific, and poorly understood [128].