## 2 Materials and Methods
### Soil Respiration Measurements  
Systematic monthly measurements of soil respiration (R\({}_{\text{S}}\)) were conducted from March 2015 to December 2017 in the OG, MS and ES sites; and from March to December 2019 only in the OG and MS locations. The experimental design for R\({}_{\text{S}}\) measurements at each site consisted of a starting central point, where four permanent 60 m transects were distributed in direction of each cardinal point (N, S, E, W). Within each transect, sixteen PVC soil collars (10 cm diameter and 8 cm in height) were installed with a 20 m distance among them. Due to site access conditions to sampling points over different years, between eight and twelve soil collars were measured at each site during each sampling campaign. All measurements were performed within a time span of three hours between 9 a.m. and 12 p.m. to avoid drastic temperature changes and potentially being representative of daily means [66; 67].  
R\({}_{\text{S}}\) measurements were carried out with a soil portable infrared gas analyzer (LI-8100, LI-COR Biosciences, Lincoln, Nebraska, USA) coupled to a 10 cm survey chamber (model: 8100-102, LI-COR Biosciences, Lincoln, NE, USA). Measurement cycles started by measuring the depth of each soil collar from the soil surface to the top, in order to adjust the total volume of the system that is required for flux calculations. Changes in soil CO\({}_{2}\) concentration were measured and recorded for 180 s; in each soil collar a 20 s prepurge prior to each measurement with the soil chamber open and a 20 s postpurge after each measurement was completed in order to remove possible remaining gas inside the soil chamber and the system [68; 69]. Finally, R\({}_{\text{S}}\) rates were derived by fitting a linear equation in SoilFluxPro(version 4.0.1, LI-COR Biosciences, Lincoln, NE, USA); the first 30 s recorded of the dataset were discarded to allow stabilization conditions inside the chamber in the field.  
In addition, soil temperature was measured with a 15 cm-long thermocouple thermometer inserted in a 45-degree angle (Barnant Co., Barrington, IL, USA.) and 12 cm-long soil moisture probe (Theta Probe ML2x, Delta Services, Cambridge, UK) was used for soil volumetric water content; these measurements were conducted simultaneously in an adjacent area to the soil collars. Carbon (%C) and nitrogen (%N) concentrations in soil were determined from eight composite samples per site. Samples were weighted (3.5 mg) and loaded in tin pressed capsules (5 \(\times\) 9 mm) and the C and N contents were obtained by flash combustion in an elemental analyzer (Flash 2000; Thermo Fisher Scientific, Waltham, MA, USA). Soil texture and pH were estimated with the Bouyoucos method and a pH meter (1:2 H\({}_{2}\)O), respectively. Soil physicochemical variables for each site are presented in Table 1.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**Soil Texture**} & \multirow{2}{*}{**Bulk Density**} & \multirow{2}{*}{**pH**} & \multirow{2}{*}{**\%C**} & \multirow{2}{*}{**\%N**} & \multirow{2}{*}{**C:N**} \\ \cline{2-2}
**Site** & & & & & & & & \\ \cline{1-1} \cline{6-10}  & \multirow{2}{*}{**Sand**} & & & & & & & \\  & & & & & & & & \\  & & & & & & & & \\ \hline OG & 41 & 33 & 26 & 1.70 \(\pm\) 0.14 & 6.70 \(\pm\) 0.07 & 2.34 \(\pm\) 0.20 & 0.19 \(\pm\) 0.01 & 12.68 \(\pm\) 1.01 \\ MS & 46 & 31 & 21 & 1.80 \(\pm\) 0.13 & 7.23 \(\pm\) 0.06 & 1.94 \(\pm\) 0.41 & 0.11 \(\pm\) 0.00 & 18.53 \(\pm\) 0.28 \\ ES & 55 & 25 & 19 & 1.91 \(\pm\) 0.12 & 6.78 \(\pm\) 0.10 & 2.48 \(\pm\) 0.35 & 0.20 \(\pm\) 0.02 & 12.15 \(\pm\)