## 3 Results
### Seasonal Effects of Soil Temperature and Soil Water Content on Soil CO\({}_{2}\) Efflux
Average values of Ts (soil temperature, \({}^{\circ}\)C) and Sw (soil water content, %) within each adjusting period followed by different letters reflect significant differences ([PERSON]’s LSD test, 95% probability, \(\alpha=0.05\)). \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**Years** & **Seasons** & \(\beta_{0}\) & \(\beta_{0}^{{}^{\prime}}\) & \(\alpha\) & \(\alpha^{\prime}\) & \(\beta_{1}\) & \(\beta_{1}^{{}^{\prime}}\) & \(p\) & \({\bf R^{2}(\%)}\) \\ \hline \multirow{4}{*}{2016} & Spring & \(0.52\pm 0.08\) & n.s. & \(0.26\pm 0.06\) & n.s. & n.s. & n.s. & 0.00 & 36.2 \\  & Summer & \(0.40\pm 0.08\) & n.s. & n.s. & n.s. & n.s. & 0.60 \(\pm\) 0.15 & 0.00 & 45.4 \\  & Autumn & \(0.09\pm 0.01\) & n.s. & n.s. & n.s. & n.s. & n.s. & n.s. & - \\  & Yearly (2016) & \(0.47\pm 0.04\) & n.s. & n.s. & 0.21 \(\pm\) 0.05 & n.s. & n.s. & 0.00 & 29.8 \\ \hline \multirow{4}{*}{2017} & Spring & \(0.21\pm 0.16\) & n.s. & \(0.23\pm 0.09\) & n.s. & n.s. & 0.11 \(\pm\) 0.05 & 0.00 & 26.1 \\  & Summer & \(0.17\pm 0.15\) & \(0.38\pm 0.2\) & n.s. & n.s. & n.s. & nthe young site (Tables 3 and 4). In addition, Model 1 reached the highest goodness of fit in spring 2018 (R\({}^{2}\) = 94.1%; Table 3). In this model fitted for spring 2018, the high weight of the \"soil water\" variable (1.09) reflected that the exceptional CO\({}_{2}\) efflux rate was mainly due to high edaphic moisture levels. The soil water content seems to control the fitted models of soil respiration under two microclimatic conditions (Table 4): (i) under drought or low edaphic humidity (summer 2016 and spring 2017), and (ii) under high levels of soil moisture content (Sw \(>\) 25%) coinciding with warm-temperate temperatures (15-20 \({}^{\circ}\)C) in the growing season (conditions in spring of 2018). These microclimatic conditions also coincided with the season of the highest CO\({}_{2}\) efflux recorded in both woodlands (especially in the mature site; Figure 4). The univariate model (Model 2, soil respiration as a function of soil temperature) was only significant in spring 2016 (with moderate soil water content levels) and yearly or throughout all seasons (Tables 3 and 4). Univariate models explained no more than 37% of the variance in CO\({}_{2}\) efflux (minor compared to when Sw was included in the models). Model 2 was the same for young and mature woodland areas in spring 2016, whereas when the model was fitted for all seasons (annual data in 2016, 2017, and all data pooled), two models resulted as a function of the woodland type. Thus, the model explained different annual rates of soil respiration for both types of juniper woodland as a function of only the soil temperature: for a certain increase in soil temperature (Ts), the variation in soil CO\({}_{2}\) efflux was significantly greater in the young juniper woodland, the most productive site (for example 1.40 vs. 1.20 in 2017). In these cases, the intra-annual effect of soil water content was confounded with the evolution of the soil temperature. Consequently, the global temperature coefficient, Q\({}_{10}\) (rate of respiration increases when the temperature increases by 10 \({}^{\circ}\)C), was significantly higher for the young woodland (1.40) than for the mature one (1.20). Regardless of the reference temperature (0 \({}^{\circ}\)C), Q\({}_{10}\) was invariant when the annual data were fitted by utilizing the exponential form. Finally, for winter and autumn in the two woodland types, and in summer 2017 also for both woodlands (when soil moisture was minimal), the resulting models showed that soil respiration was independent of the soil temperature and soil water (Tables 3 and 4), thus representing a constant function or value (e\({}^{\beta 0}\)). For this, the regression was not significant (\(p>\) 0.05; Table 3). The constant value indicated a higher level of respiration from summer to winter, and in the colder season, the estimated soil respiration was minimal (0.64 \(\mu\)mol CO\({}_{2}\) m\({}^{-2}\) s\({}^{-1}\)).