engleski

Orchid diversity in a special habitat mosaic on the southern slopes of Požeška Gora hill (Croatia)

The present study aimed at assessing the floristic diversity of a semi-natural habitat mosaic consisting of different vegetation types such as grasslands, scrubland and forest fringes hosting a diverse assemblage of protected orchid species. The area under investigation covers approximately 0.8 ha and is situated above the village Stara Kapela (45°14'11"N, 17°41'16"E), with an altitude range of 100 to 225 m.a.s.l.. It is located at the southern slopes of Požeška Gora hill (616 m.a.s.l.) in the south-eastern part of the Slavonian mountain range (Eastern Croatia). The former large areas of characteristic oak forests were cut down almost to the ridge of Požeška Gora due to the spreading of villages and other anthropogenic habitats which prevail in the area of Stara Kapela, such as pastures, meadows, agricultural fields, hedges, orchards and vineyards. The weekly-based floristic surveys were undertaken from May through October 2015. The studied area was dominated by taxa characteristic of continental dry calcareous grassland communities (Festuco- Brometea) influenced by the surrounding vegetation of sub-continental thermoxerophilous forests of Quercus petraea and Quercus cerris. Among the total of 186 plant taxa recorded, the most diverse families were Fabaceae (17 taxa), Lamiaceae (15 taxa), Asteraceae (14 taxa) and Rosaceae (11 taxa). The family Orchidaceae was surprisingly diverse with 11 taxa sorted to 6 genera: Anacamptis, Cephalanthera, Epipactis, Gymnadenia, Ophrys and Orchis. All these orchids are strictly protected by the Croatian Nature Protection Act, two are additionally listed as nearly threatened, five as vulnerable and one as data deficient species. Habitats with similar features in Croatia and Europe, especially those that host a rich suite of orchid species, have been included in the NATURA 2000 Ecological Network as “important orchid sites” on semi-natural dry grasslands and scrubland facies on calcareous substrates (habitat code: 6210). Furthermore, the remnants of thermophilic forests in Croatia are excluded from regular harvesting being very important from the point of biodiversity. This site is not assigned to any nature conservation category so further investigation into the diversity and distribution of orchids, as well as many other important plant taxa growing on this relatively small area is needed to provide a basis for the assessment of priorities for conservation of this floristically very important habitat.

orchid diversity ; calcareous grasslands ; Festuco-Brometea ; Stara Kapela

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