IDRIJA UNESCO GLOBAL GEOPARK
The wilderness and impenetrability of nature make for the best guardians of the plant world in the Upper Idrijca Landscape Park. The varied and unique flora, with the presence of Dinaric, Alpine and sub-Mediterranean plant elements, is a reflection of the specific edaphic climatic conditions and the varied geological structure. The steep slopes of the Idrijca and Belca river valleys and the tributary torrent ravines are the habitat of many plant species. Among them, there are a number of botanical peculiarities, of which all three species of primrose are worth mentioning: Carniolan primrose (Primula carniolica) – a Slovenian endemic plant, auricula (Primula auricula), and their hybrid, Idrija primrose (Primula x venusta). A number of protected species thrive here: the beautiful lady’s-slipper orchid (Cypripedium calceolus), flower of the sweet-lady (Gentiana clusii), common holly (Ilex aquifolium), Carniolan lily (Lilium carniolicum), orange lily (Lilium bulbiferum), mouse thorn (Ruscus hypoglossum) and yew (Taxus baccata). There are also species on the Red Data List of Threatened Vascular Plants in Slovenia, such as the idrija primrose and the round-leaved sundew (Drosera rotundifolia), as well as many others. The specific growing conditions allow representatives of Alpine flora to thrive – they have probably survived here since the Ice Age: the aforementioned Carniolan primrose, flower of the sweet-lady, hairy alpenrose (Rhododendron hirsutum), Rhodothamnus chamaecistus, alpine butterwort (Pinguicula alpina), and others. The sunny, warm slopes are home to thermophilic flora: burning bush (Dictamnus albus), European smoketree (Cotinus coggygria), chimney bellflower (Campanula pyramidalis), and others.
Several plant species are protected by the Nature 2000 Directive on the conservation of natural habitats and of wild fauna and flora (92/43/EEC). The Trnovo Forest Plateau –Nanos is a wooded area of the Trnovo Forest Plateau and Nanos with the presence of habitat types that are prioritised for conservation; it is the habitat of endangered plant species, such as hladnikia (Hladnikia pastinacifolia) and Bertoloni columbine (Aquilegia bertolonii).
Botanically, the most interesting areas are the vicinity of the Wild Lake, Strug, Putrih walls, Sončni rob, and Hudo Polje and Mali Govci (indigenous areas of black pine – a glacial relict).
The Idrija Hills are characterised by high forest cover due to the karst nature of the land and the morphological conditions. These forests have been managed for almost 500 years and have lost much of their natural structure. The formerly mixed forests in the central part have been transformed by management into almost pure beech stands of one generation. Dr Wraber called the beech “the stepmother of the Idrija forests”, probably because it is so prevalent almost everywhere, from the lowest to the highest reaches. In the past, as a result of bare-earth management, the beech displaced the fir tree in many places. When natural regeneration failed, fir was later often replaced by planted spruce, which occurs naturally in the Idrija Hills only in the freezing ravines.
Noble deciduous trees are also important stand builders in the forests of Idrija. The most common of these is the sycamore, followed by the ash.
The Idrija forests are dominated by fir-beech communities, followed by various beech-forest communities. The sunny slopes are covered by thermophilous beech and European hop-hornbeam forests. In smaller areas on non-carbonate substrates, highly productive fir stands are widespread, with a mixture of beech and noble deciduous trees.
In the protected area of the Upper Idrijca Landscape Park, the forests are defined as “special purpose forests”, where the most important aspect is the protection of the natural and cultural heritage, with an emphasised recreational function.