20.500.12556/DiRROS-22149 Plant diversity decrease and directional species turnover induced by shifting overstory dominance in the oak-hornbeam forest reserve over 50 years 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. lowland primary forest Quercus robur dieback Carpinus betulus Light availability taxonomic homogenization semi-permanent plot nižinski primarni gozdovi odmiranje Quercus robur Carpinus betulus svetlobne razmere Taksonomska homogenizacija true false true Angleški jezik Slovenski jezik Znanstveno delo 2025-05-05 14:48:39 2025-05-05 14:48:40 2026-01-28 12:57:15 0000-00-00 00:00:00 2025 0 0 Nasl. z nasl. zaslona; Opis vira z dne 5. 5. 2055; str. 1-12 article no. ǂ152742 Vol. 327 2025 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 630*1 1618-0585 10.1016/j.flora.2025.152742 234804739 https://www.sciencedirect.com/science/article/pii/S0367253025000726?via%3Dihub 1 45a5f21f-29af-11f0-963a-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=32039 RAZ_Kermavnar_Janez_2025.pdf RAZ_Kermavnar_Janez_2025.pdf 1 526F4A6DB9F3CF994060AE0BE29D4925 a6db7cf3f0b505405dacaafac0e6e57ba1d9fb41230264f0fe22c61f5fe2e33e 4cee984a-29af-11f0-963a-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=32040 Gozdarski inštitut Slovenije 0 0 0