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Povzetek: Maintaining the conservation status of habitat types such as the ravine forests (Tilio-Acerion) assessed in this study is a priority of the European Natura 2000 network. Ravine forests often occur in smaller, fragmented areas, but are widely distributed throughout European forests. Reliable indicators of the conservation status of Natura 2000 habitats, which support monitoring and reporting under Article 17 of the Habitats Directive, are often not available. Therefore, we tested a set of 161 structural and compositional variables as potential indicators of the conservation status of close-to-nature managed ravine forests in a Natura 2000 site in eastern Slovenia. The studied forests ranged from Acer pseudoplatanus-dominated stands to those dominated by Fraxinus excelsior or Tilia species. Most forests were classified as having either a favourable or inadequate conservation status. The main pressures included game browsing and mortality of the key tree species, primarily caused by invasive alien fungi. Favourable conservation status was associated with less intensively managed Tilia-dominated stands on rocky ridges and steep slopes. It was also linked to higher tree layer cover, particularly of Acer pseudoplatanus, in well-preserved forest stands. Conversely, indicators of bad conservation status were associated with Fraxinus excelsior-dominated stands that had been severely affected by invasive alien fungi, resulting in increased volumes of standing and lying deadwood. The resulting tree mortality created more open stand canopies with increased light availability at the forest floor, as indicated by the higher number of plant species in the herb and shrub layer. The conservation status of ravine forests is likely to be increasingly threatened by the adverse effects of climate change, including pests and disease outbreaks and other disturbances. To ensure the continued favourable conservation status of ravine forests, it is essential to monitor key indicators and apply appropriate forest management measures.
Ključne besede: forest habitats, vegetation, pressures, conservation, indicators, Eastern Slovenia, forest stands
Objavljeno v DiRROS: 09.09.2025; Ogledov: 270; Prenosov: 119
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Ključne besede: vegetacija, tla, rastišče, ekologija gozda, delavnice, Javna gozdarska služba, Slovenija
Objavljeno v DiRROS: 20.06.2025; Ogledov: 410; Prenosov: 177
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Ključne besede: okoljska DNK, talna biodiverziteta, talni nevretenčarji, izcedna voda, kiti za ekstrakcijo DNK
Objavljeno v DiRROS: 05.06.2025; Ogledov: 533; Prenosov: 224
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Objavljeno v DiRROS: 05.06.2025; Ogledov: 381; Prenosov: 165
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Povzetek: Questions The long-term response of understorey vegetation to increasing tree mortality has rarely been addressed in resurvey studies. For two Quercus-dominated forest types, we asked: (a) How did overstorey alterations, induced by canopy mortality, affect understorey diversity and composition? (b) Is there a signal of global change effects on understorey communities? (c) Are these assemblages experiencing a homogenization process? Location Five sites in Quercus robur (QR) and four sites in Q. petraea (QP) forests, Slovenia. Methods We studied changes in vascular plants in the understorey layer from 1992/1993 to 2023 across 45 permanent 20 m × 20 m plots in QR and QP forests, respectively. Vegetation surveys were carried out following the standard Braun-Blanquet method. We compared original surveys with recent resurveys using multivariate analysis, ecological indicator values (EIV), plant traits and methods that quantify changes in individual species. Results Since the early 1990s, tree layer cover decreased from 95% to an average of 55% in QR, whereas it remained relatively high (77%) in QP plots. This resulted in denser understorey vegetation and a significant increase in plot-level species richness in QR forests, but a slight decrease in QP forests. The extensive loss of canopy cover and disturbance effects in QR forests caused significant changes in species composition. Species turnover in QR was driven by colonization of new disturbance-tolerant taxa characterized by ruderal traits, whereas the compositional shift in QP was to a greater extent due to species losses. We detected a process of vegetation thermophilization (increase in EIV-temperature), suggesting an effect of rapid climatic warming. Understorey communities are now more similar to each other than 30 years ago, indicating a decrease in beta-diversity (floristic homogenization). Conclusions Despite some common trends, vegetation responses were forest type-specific. Our study presents evidence of understorey vegetation changes triggered by increased canopy mortality (a strong local driver particularly in QR plots) and also points to the signal of global change symptoms (thermophilization, homogenization), which acted rather independently from the observed decline in tree layer cover.
Ključne besede: floristic homogenization, forest disturbances, permanent vegetation plots, Quercus robur, Quercus petraea, resurvey study, Slovenia, thermophilization, tree layer cover
Objavljeno v DiRROS: 11.11.2024; Ogledov: 673; Prenosov: 568
Celotno besedilo (18,09 MB)
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