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Abstract: Due to a long history of various anthropogenic pressures, lowland forest reserves are scarce and lack historical datasets suitable for analysing long-term vegetation trends. This study investigated changes in plant diversity and species composition in the long-untouched Krakovo forest reserve, the only preserved remnant of lowland oak-hornbeam forests with primary status in Slovenia. The original vegetation sampling was conducted in the 1970s. In 2024, we resurveyed 30 semi-permanent plots capturing the natural variation in soil moisture gradient. We found the decline of Quercus robur in the upper tree layer and the expansion of shade-casting tree Carpinus betulus in the lower tree layer, a pattern mainly attributed to the lowering of the groundwater table. This shift in overstory dominance manifested in a directional change of herb-layer composition associated with high species turnover (61 %). The deterioration of light conditions at the forest floor resulted in significant decrease of species richness, accompanied by the process of taxonomic homogenization. The analysis of Ellenberg indicator values revealed a reorganization of the plant communities in response to the increasingly shaded and cooler understory environment, benefitting a limited number of perennial herbs preferring closed canopies. The change towards nutrient-demanding species was probably caused by improved litter quality, nitrogen input from agricultural areas and nutrient release from accumulated deadwood. In terms of soil moisture, the reserve still exhibits a mosaic of interchanging distribution between wetter and more mesic habitats. However, given that oak natural regeneration is very poor, we anticipate even more drastic vegetation changes in the future.
Keywords: lowland primary forest, Quercus robur dieback, Carpinus betulus, Light availability, taxonomic homogenization, semi-permanent plot
Published in DiRROS: 05.05.2025; Views: 143; Downloads: 52
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Keywords: podnebne spremembe, gozdovi, poškodbe gozdov
Published in DiRROS: 14.03.2025; Views: 201; Downloads: 184
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Abstract: 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.
Keywords: floristic homogenization, forest disturbances, permanent vegetation plots, Quercus robur, Quercus petraea, resurvey study, Slovenia, thermophilization, tree layer cover
Published in DiRROS: 11.11.2024; Views: 344; Downloads: 309
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Keywords: vrednotenje, vplivi, državni prostorski načrt, vetrna elektrarna, gozdovi, gozdarstvo, Rogatec
Published in DiRROS: 08.11.2024; Views: 366; Downloads: 0
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Abstract: V letu 2024 obeležujemo dvajset let aktivnosti Intenzivnega monitoringa gozdov v Sloveniji, ki je del mednarodnega programa ICP Forests in Konvencije UN ECE CLTRAP. Glavni namen aktivnosti je spremljati učinke onesnaženosti zraka in drugih dejavnikov na gozdne ekosisteme. Na desetih hektarskih ploskvah v Sloveniji potekajo različna opazovanja in meritve ter stanja drevja po mednarodno usklajenih protokolih. Letna poročila o stanju gozdov so javnosti dostopna na spletnih straneh Gozdarskega inštituta Slovenije in Inštituta za gozdne ekosisteme Thünen v Nemčiji. Rezultati intenzivnega monitoringa gozdov so pomembni za razumevanje odziva drevja na okoljske spremembe, na ekstremne dogodke, bolezni in druge dejavnike in so del raziskovalne dejavnosti ter razumevanja razvoja gozdov na izbranih objektih.
Keywords: Program intenzivni monitoring gozdov, Slovenija, ICP Forests
Published in DiRROS: 07.11.2024; Views: 352; Downloads: 113
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