Simulating alternative forest management in a changing climate on a Pinus nigra laricio stand at the Bonis watershed, Calabria

Forest ecosystems contribute significantly to the global carbon cycle by absorbing and storing CO 2, thus potentially mitigating the effects of anthropogenic climate change. The Mediterranean region, one of the world's biodiversity and climate change hotspots, is projected to become dryer and warmer in the future, with an increased likelihood of extreme heatwaves and droughts. These increasing environmental constraints could trigger the transition from a positive to a negative carbon balance in Mediterranean forest ecosystems, with profound consequences on forest persistence and dynamics. In this context, there is a high expectation towards sustainable forest management practices to counterbalance possible climate-change-induced carbon losses. Often the lack of long-term and systematic monitoring information represents a major limitation to the formulation of effective forest management policies. In this respect, projections using forest ecosystem models can be used to test the effect of different management options on Mediterranean forests in a changing climate. Here, we simulated the growth of a Pinus nigra laricio stand in the Bonis experimental watershed, located in the mountain area of Sila Greca, Calabria. The area, at about 1100 m above sea level, represents one of the southernmost pine forests in Europe and has been monitored since 1986, including an Eddy-Covariance tower since 2003 as part of the Euro-flux-Carboitaly network. The simulations were performed using 3D-CMCC-FEM, a process-based forest model that simulates the main eco-physiological processes and the key factors that control the carbon and water cycle. First, we evaluated model performance by comparing the simulated diameter at breast height, stand density and gross primary productivity with past measurements. Then, we simulated the growth of the forest stand until 2095 at increasing levels of climate warming and according to a portfolio of different management scenarios, including different thinning frequencies, intensities, natural regeneration and replanting, which reflect alternative goals. Overall, management seemingly mitigates the effect of climate change by increasing primary productivity and forest biomass compared to the unmanaged stand, albeit differently depending on the chosen strategy. Therefore, careful and goal-oriented planning of management activities in Mediterranean forests has the potential to preserve and possibly enhance their functionality in a warmer and drier climate.