Group-selection system as alternative management of Scots pine (Pinus sylvestris L.) forests facing climate change

Abstract The Scots pine ( Pinus sylvestris L.) is economically and ecologically the most important forest tree species in Poland with its aerial share estimated at 59% and share in growing stock at 68%. Pine forests have been managed according to even-aged silviculture for decades, resulting in a simplified structure and increased vulnerability to climatic stress. Structurally simple forests also show low resilience and adaptability to the observed global changes. The growing awareness of the risks associated with global change is drawing particular attention to the need for alternative management of pine forests that meets the expectations of the public and foresters themselves. In 1992, an experiment with uneven-aged silviculture for pine forest was established in the Gubin Forest District (western Poland). Based on data collected from 49 permanent circular plots (size of 500 m 2 each) covering approximately 30 ha of Scots pine forest, the effect of such silviculture on stand structure was analyzed. Dbh, total tree height, tree status, and tree coordinates (x, y) were measured on each plot. Measurements and observations were taken twice, in 1992 and 2019. Structural indices describing different aspects (size structure, vertical structure, spatial structure) were calculated. The dynamics of the stand structure were then analyzed over 27 years, during which the forest was managed under alternative management strategies. The results showed that group-selection cuttings promote strong differentiation of stand structure. The positive effect of such silviculture can be observed in each aspect of the stand structure. Together with other research findings, the results confirm the effectiveness of this alternative silviculture to diversify simplified pine forests to be better adapted to novel environmental conditions.