Austrian Pine has done its positive contribution to the Karst. Stands of Austrian pine have become unstable and vulnerable, and their further development into more natural and stable structures has slowed down. Therefore, the pine stands should be gradually converted to more resistant stands consisting of autochthonous species. On the area of Sežana - Komen Karst two locations have been chosen according to terrain similarities. Older stands of Austrian pine were selected; those stands that were just before the introduction of regeneration, where tree seedlings and seed trees of oak were present. Research was conducted in four stand types: closed stand, diffusely opened stand, stand opening and the edge of the opening. In each stand type systematic plots (herb plots) as well as plots defined by the presence of oak seedling were installed (oak plots). In addition to ecological factors and vegetation seed trees within a radius of 80 m were also sampled. The results have shown that seedlings were dominated by manna (flowering) ash. The estimate of the oak seedlings density was 0.24 per m2. The maximum number of seed trees was in the proximity of diffusely opened stands and the lowest number around stand openings. It was not confirmed that there is a link between oak seedling density and number of seed trees. Additionally, it was not demonstrated that the greater proximity of herb plots towards oak seed trees resulted in higher density of oak seedlings. Considerable density of oak seedlings was found in this study, therefore special care should be taken to favour advanced oak regeneration. With proper tending, protection and silvicultural measures, oak seedlings could be promoted. In this way Austrian pine plantations could gradually convert to mixed stands of oak and native noble broadleaf stands of higher quality and resilience.
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