This article describes a field- and laboratory-based framework that can be used to monitor the C balance in Mediterranean pine forest ecosystems under different management practices that determine their structure and function. By jointly monitoring stand structure, gas exchange, litter, and decomposition dynamics, this protocol enables the assessment of how management-driven changes regulate carbon uptake, turnover, and losses, thereby affecting carbon sequestration potential. As an example, we suggest the implementation of the protocol at ten (10) permanent monitoring plots across three study areas located in Greece. The first group of plots represents a post-fire chronosequence in pine stands with no management interventions. The second group includes pine stands that exhibit variation in overstory and understory density driven by differences in microclimate and management history. The third group consists of peri-urban pine stands subjected to thinning of varying intensity. The monitoring protocol is implemented across all plots and the collected data can be classified into three analytical domains: (a) demography, encompassing measurements of tree growth and mortality; (b) litter and decomposition dynamics, involving the quantification of litterfall and its seasonality and the estimation of its decomposition rates; and (c) gas exchange, focusing on measurements of leaf photosynthesis and respiration (including relevant leaf functional traits) and monitoring of soil respiration. These three data domains can be used to comparatively consider the effect of forest management on key ecosystem processes and to constrain local-scale vegetation dynamics models.

Background and aims Understanding the main drivers of decomposition, a fundamental ecosystem process, is crucial for predicting carbon dynamics in Mediterranean pine forests in the context of climate change. Litter decomposition is highly influenced by micro-environmental conditions, litter chemistry and forest management practices. Methods A multi-plot decomposition experiment was conducted in Pinus brutia and Pinus halepensis dominated forests at three regions in Greece. In each plot, different forest management practices have been implemented over the last decades (overstory thinning, understory removal and lack of management). The mass loss of pine needles and standardized material (cellulose papers, wood sticks) was systematically measured along with micro-environmental conditions. Nonlinear mixed-effect models were used to explore the influence of species, stand structure, and micro-climatic and soil conditions on the early decomposition rates. Results Needle litter in P. halepensis dominated stands decomposed approximately twice as fast as litter in P. brutia stands. Atmospheric temperature and soil water content interaction had prominent effect across all regions and materials, along with a positive effect of soil pH. The analysis of the decomposition rates of cellulose papers revealed an across-region effect of microclimate (air temperature and soil water content) and stand structure (total basal area and leaf area index). For wood sticks, air temperarute interaction with soil water content and pH were the dominant across-plot predictors of decomposition. Conclusion The process of early-stage decomposition across regions could be primarily controlled by variation in soil conditions, with microclimate and stand structure operating at a smaller (plot-level) scale.

Background and aims Understanding the main drivers of decomposition, a fundamental ecosystem process, is crucial for predicting carbon dynamics in Mediterranean pine forests in the context of climate change. Litter decomposition is highly influenced by micro-environmental conditions, litter chemistry and forest management practices. Methods A multi-plot decomposition experiment was conducted in Pinus brutia and Pinus halepensis dominated forests at three regions in Greece. In each plot, different forest management practices have been implemented over the last decades (overstory thinning, understory removal and lack of management). The mass loss of pine needles and standardized material (cellulose papers, wood sticks) was systematically measured along with micro-environmental conditions. Nonlinear mixed-effect models were used to explore the influence of species, stand structure, and micro-climatic and soil conditions on the early decomposition rates. Results Needle litter in P. halepensis dominated stands decomposed approximately twice as fast as litter in P. brutia stands; however, these species-specific differences were probably masked by micro-environmental variation and therefore could not be attributed to differences in litter chemistry. The analysis of the decomposition rates of cellulose papers revealed an across-region positive effect of pH that interacts with variation in microclimate (air temperature and soil water content) and stand structure (total basal area and leaf area index). For wood sticks, pH was the single across-plot predictor of decomposition. Conclusion The process of early-stage decomposition across regions could be primarily controlled by variation in soil conditions and their microbial communities, with microclimate and stand structure operating at a smaller (plot-level) scale.