## 1 Introduction  
Although forests at a global scale act as one of the main biospheric carbon (C) sinks, storing 2.4 \(\pm\) 0.4 Pg C on an annual basis [1], some forest ecosystems may release C at specific temporal scales [2, 3], and thus detailed accounting of the C-fluxes and understanding of the factors that control them is essential for designing adaptive forest management policies. The amount of C that is captured in any ecosystem per unit area and time is defined as the Net Ecosystem Productivity (NEP g C m\({}^{-2}\) s\({}^{-1}\)), often calculated as the difference between Gross Primary Productivity (GPP g C m\({}^{-2}\) s\({}^{-1}\)) and ecosystem Respiration (R\({}_{\text{eco}}\) g C m\({}^{-2}\) s\({}^{-1}\)). GPP represents the amount of C enchenained by plants in the form of Carbon Dioxide (CO\({}_{2}\)) through photosynthesis. R\({}_{\text{eco}}\) refers to the release of CO\({}_{2}\) back to the atmosphere due to the respiration of all living organisms in the ecosystem. Two components of R\({}_{\text{eco}}\) are usually identified: autotrophic respiration (R\({}_{\text{aut}}\) g C m\({}^{-2}\) s\({}^{-1}\)and heterotrophic respiration (R\({}_{\rm het}\) g C m\({}^{-2}\) s\({}^{-1}\)). The dynamic temporal and spatial balance between GPP and R\({}_{\rm eco}\) define whether an ecosystem acts as a sink or source of C [4]. Understanding the dynamics of the above ecosystem fluxes is crucial for modeling and projecting the role of forests in the global carbon cycle under current and future environmental conditions [5]. The rate and annual variability of photosynthetic activity is considered as the primary control of GPP. Environmental factors such as solar radiation [6], air temperature [7] and soil water content [8] are known to regulate the rate of photosynthesis at both the leaf and the canopy levels. In Mediterranean ecosystems, water stress can limit photosynthesis [9]. Experimental studies on Mediterranean plants have shown that the maximum rate of photosynthesis is achieved at lower temperatures than the theoretical optimum, when plants are under water stress, helping to avoid further water loss [10]. Stomatal closure, in response to water stress, limits the amount of CO\({}_{2}\) uptake as well as the internal diffusion of CO\({}_{2}\) from the substomatal cavities to the chloroplast, leading to lower photosynthetic rates [11] during periods of limited water availability. Even though photosynthetic metabolism is minimally impacted at stomatal conductance (Gs) above 0.1-0.15 mol H\({}_{2}\)O m\({}^{-2}\) s\({}^{-1}\), plants in the Mediterranean region often exhibit Gs lower than this threshold [10]. After such a severe event, plants require time to recover their photosynthetic rates, ranging from a day [12] to weeks, or even months [13], after the first rainfall event. Conversely, plants under Mediterranean climatic conditions exhibit higher temperature thresholds for tissue necrosis and lower inhibition of photosynthesis under high temperatures compared to plants in other regions [14; 15]. The above underlines that accurate simulations of ecosystem dynamics should consider the potential adaptations that plants have developed, particularly at local scales and environmental conditions, highlighting the importance of regional scale process-based models that are parameterized with empirical monitoring data [6]. Plant autotrophic respiration is frequently modeled as the sum of maintenance and growth respiration [16; 17]. An approach in process-based models is to estimate growth respiration as a fraction of plant Net Primary Productivity (NPP), and maintenance respiration as a function of biotic and abiotic factors [17]. However, R\({}_{\rm aut}\) is also empirically approximated through a linear relationship with plant size [18], challenging the dependence of maintenance respiration on abiotic factors.