Climate change mitigation by forests: a case study on the role of management on carbon dynamics of a pine forest in South Italy

In the last decades, the problem of global changes has been of major importance, in particular the increase in CO2 concentration in the atmosphere with the consequent rise in the average temperature of the planet. In this context forests and their rational/optimal management is very important to contribute to the mitigation of the effects of climate change. Studying in deep how forest management modifies the processes that control carbon dynamics during stand development and in response to climate change, is therefore key to improve our understanding of land-based climate mitigation. For these reasons, modelling tools are increasingly used by both forest ecologists, who face the challenge of transferring knowledge to stakeholders and the general community, and forest managers, who benefit from the development of scenario-based supports for decision-making. In particular, the objective of this study is to analyse the impact of the current and alternative forestry practices on carbon fluxes in a pine forest in South Italy under scenarios of climate change. This was done by simulating three different forest planning scenarios using the 3D-CMCC-CNR-FEM model, and evaluated over time with respect to carbon fluxes variables. The first part of thesis has focused its attention on analysis of dendrometric characteristics of the forest, sensitivity analysis and Bayesian calibration of the model. This has allowed to estimate the uncertainty of the model output in comparison with the measured data and its analysis, in response of the model outputs. The second part is focused, firstly, on analysing the different behaviour of the forest under management (reference management: rotation: 90 yrs; interval: 15 yrs; intensity: 25%), in comparison with the "not managed" forest in terms of temporal variation of Gross Primary Production (GPP), Autotrophic Respiration (RA), woody C-stock and Net Primary Production (NPP) under different climate scenarios. In this respect, results show that a progressive reduction in forest cover through thinning confers beneficial effects on the growth and development of the remaining plants. If management, on the one hand, due to a reduction in leaf area, determines a decrease in photosynthesis as a whole, on the other hand it creates better light conditions that contribute to increase and make the photosynthetic process of the remaining plants more efficient and consequently contribute to the enhanced NPP of forest ecosystems. Secondly, the analysis focused its attention on the woody C-stock and NPP dynamics by comparing different forest management options. The purpose is to analyse in detail how the variation of several management factors (rotation, interval, intensity), affect the forest development under different climatic scenarios. From the analysis it emerged that the factor that determines a greater weight on the productivity of the forest is the choice of rotation. In particular, it has been observed that an increase in rotation length has beneficial effects not only on the carbon stock but also on carbon sequestration. This would suggest the hypothesis that in conditions of climate change, in Mediterranean climate and for conifer forest, careful forest management characterized by rotations, intervals and intensities well calibrated on specific biotic and abiotic conditions may guarantee a carbon assimilation comparable in an undisturbed forest maximizing the total carbon stock at the same time. This confirms the importance of sustainable forest management, which not only provides for the optimal maximization of timber production, but also has the potential to guarantee the performance of various ecosystem services that are important for the community.