Effect of an Innovative Thinning Method on the Mechanical Stability of an Artificial Black Pine (Pinus nigra Arn.) Stand: The Case Study of Pratomagno, Tuscany, Italy

Abstract Reforested and afforested areas play a key role in providing ecosystem services, contributing to the socio-economic well-being of societies. Among the forest species used for the reforestation and afforestation, black pine is one of them, and Italy is among the areas where this species has been chosen. This study aims to investigate the mechanical stability of an artificial black pine forest approximately 10 years after two different types of thinning (selective and from below). To achieve this objective, the slenderness ratio was chosen as stability parameter, as it is well suited due to its practicality of calculation and the presence of threshold values in the literature. What emerges from the study is that the slenderness ratio shows no statistically significant difference between the different thinning techniques. This lack of difference could be due to a windthrow that occurred in 2017, which acted as a “natural” thinning agent. Future research should focus on understanding the right time interval between one thinning operation and the next, also considering other aspects, such as the profitability of the timber removed during the operations and other ecosystem services, such as soil protection.