Abstract

Historical vegetation resurveys provide valuable insights into long-term forest dynamics and the legacy effects of past land use. We resurveyed 45 quasi-permanent vegetation plots originally recorded in 1942 in acidophilous Pinus sylvestris forests of central Slovenia to assess vegetation change after nearly nine decades of secondary succession. We analysed changes in species composition, vegetation structure, tree regeneration, taxonomic diversity across spatial scales, functional and phylogenetic diversity, ecological indicator values, and diagnostic species. The formerly relatively homogeneous pine-dominated vegetation underwent a pronounced compositional shift and differentiated into three distinct successional pathways, characterised by increasing dominance of Fagus sylvatica, Castanea sativa, or Picea abies. Although total tree-layer cover remained largely stable, P. sylvestris declined in dominance and was almost absent from the regeneration layers in 2025, indicating limited capacity for persistence under current stand conditions. Vegetation change was accompanied by a shift towards shadier, more mesic, and nutrient-richer conditions, and the replacement of stress-tolerant pine-forest specialists by more competitive forest species. Diversity responses were strongly scale-dependent: plot-level species richness and phylogenetic diversity declined, whereas regional species richness and compositional differentiation increased. These results show that secondary acidophilous P. sylvestris forests should not be interpreted as stable vegetation types, but as dynamic land-use legacy systems whose future development depends on local site conditions, stand development, and historical management legacies.

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