This forest type is found on relatively warm and dry sites, where beech Fagus sylvatica is replaced by other thermophilous tree species such as: Downy Oak Quercus pubescens, Hop-hornbeam Ostria carpinifolia, Manna Ash Fraxinus ornus, Sessile Oak Quercus petraea and Turkey Oak Quercus cerris. In certain sunny locations in western Slovenia (and more commonly in nearby northeast Italy) there are also evergreen Holm Oak Quercus ilex forests, typical of the Mediterranean. The largest areas of thermophilous forests are found in the sub-Mediterranean part, that is mainly in western Slovenia. Such areas include a good proportion of the Classical Karst area, Istria and the Vipava valley.
These forests are not as old and well preserved as those in the Dinarides, but are rather the result of human land use through centuries. Many forests are coppiced and/or grow on abandoned farming areas (agricultural terraces, meadows and pastures).
Despite the fact that thermophilous forests are of secondary formation, they are important habitats for some rare and protected animal and plant species.
Birds that can be observed in such forests include mainly common species such as Golden Oriole Oriolus oriolus, Nightingale Luscinia megarhynchos, Short-toed Treecreeper Certhia brachydactyla, Hawfinch Coccothraustes coccothraustes, Black Woodpecker Dryocopus martius, Grey-headed Woodpecker Picus canus Lesser Spotted Woodpecker Dendrocopos minor and Tawny Owl Strix aluco. In recent years Middle Spotted Woodpecker Dendrocopos medius has also been found in various thermophilous oak forests in the Karst region.
On sunny wooded slopes where the forest is not too dense and clearings are present Rock Bunting Emberiza cia can be found as well.
Nightingale Luscinia megarhynchos
Lesser Spotted Woodpecker Dendrocopos minor
Golden Oriole Oriolus oriolus (Photo: Bruno Dentesani)
Hawfinch Coccothraustes coccothraustes
Common mammal species in thermophilous forests include Roe Deer Capreolus capreolus, Wild Boar Sus scrofa, Fox Vulpes vulpes and Beech Marten Martes foina, that are generally common across most of Slovenia’s forests. Another common mammal is also the Eastern Hedgehog Erinaceus concolor, widespread over most of Slovenian woodlands. Large carnivores are rare and only transit through these forests. In recent years Golden Jackals Canis aureus have began to colonise this habitat and are increasingly common throughout woodlands of the Karst. Among the invertebrates living in thermophilous forests it is worth to mention two large beetles, the common Stag Beetle Lucanus cervus and the rarer Great Capricorn Beetle Cerambyx cerdo, both linked to old oak trees.
Roe Deer Capreolus capreolus
Stag Beetle Lucanus cervus
Golden Jackal Canis aureus
Great Capricorn Beetle Cerambyx cerdo
Apart from the above mentioned tree species, a few others are also typical for some thermophilous forests and include Montpellier Maple Acer monspessulanum, Mahaleb Cherry Prunus mahaleb, Cornelian Cherry Cornus mas, European Smoke-tree Cotinus coggygria and in some places the Terebinth or Turpentine Tree Pistacia terebinthus.
Plant species in the forest undergrowth include: Sesleria autumnalis, Helleborus multifidus ssp. istriacus, Butcher's Broom Ruscus aculeatus, Wild Peony Paeonia officinalis, Dittany Dictamnus albus, Chamaecytisus hirsutus, Wild Asparagus Asparagus acutifolius, Coronilla emerus ssp. emeroides, Sword-leaved Helleborine Cephalanthera longifolia, Bloody Cranesbill Geranium sanguineum, Bastard Balm Melittis melissophyllum, Knautia drymeia ssp. tergestina, Peach-leaved Bellflower Campanula persicifolia, Montpellier's Pink Dianthus monspessulanus, Bird's-nest Orchid Neottia nidus-avis. More rarely also Dog's-tooth Violet Erythronium dens-canis, Lady Orchid Orchis purpurea and Violet Helleborine Limodorum abortivum.
Wild Peony Paeonia officinalis
Dog's-tooth Violet Erythronium dens-canis
Montpellier's Pink Dianthus monspessulanus
Lady Orchid Orchis purpurea
In coastal areas, where thermophilous Mediterranean forests of Holm Oak are present, some characteristic bird species occur. These include Sardinian Warbler Sylvia melanocephala and Subalpine Warbler Sylvia cantillans and very occasionally also Eastern Olivaceous Warbler Iduna pallida.
Typical Mediterranean plants compose such evergreen forest communities: Phyllirea latifolia, Bay-tree Laurus nobilis, Lonicera etrusca, Smilax aspera, Juniperus oxycedrus, Terebinth Pistacia terebinthus, Teucrium flavum, Wild Madder Rubia peregrina, Sedum maximum.
Subalpine Warbler Sylvia cantillans
Holm Oak Quercus ilex
Sardinian Warbler Sylvia melanocephala
Terebinth Pistacia terebinthus
In the Karst area of western Slovenia, where thermophilous forests are not yet established, extensive Black Pine Pinus nigra plantations, dating back to the 19th century are found. From the biodiversity point of view they represent a species-poor habitat. Worthy of mention are just a few birds that benefit from Black Pine plantations and breed in such forests including Crested Tit Lophophanes cristatus, Coal Tit Periparus ater, Crossbill Loxia curvirostra and Black Woodpecker Dryocopus martius. Such plantations are also the favoured habitat of Red Squirrels Sciurus vulgaris.