20G1
Rila oak (Quercus protoroburoides) forests
Relationships with habitat classifications. EUNIS: G1.7642 Rila Quercus protoroburoides forests; PAL. CLASS.: 41.7642Rila Quercus protoroburoides forests.
Conservation status. BC.
Category. Critically endangered [CR – A1 B2 C3 D3 E3 F1 G2 H2 I L1].
General characteristics. This habitat type comprises coenoses dominated by Quercus protoroburoides. There are three localities with such phytocoenoses. They are far from one another and are located along the valley of Rilska river in the vicinity of Rila Monastery where climatic inversion occurs. This explains why oak coenoses occur at altitudes higher than altitude of the beech coenoses. Two of the phytocoenoses are on the eastern slope of the valley at 1400–1450 m alt. and one is on the ridge between the water catchments of Rilska River and its feeder the Iliina River. A significant part of this third locality is linked to Iliina River and has a southern exposure at 1340 m alt. The other two localities are also with southern exposure since the microslopes on which they occur face south. The areas are rocky, mostly with 25–45° slant of the slopes. The bedrocks are acidic. The soil cover is relatively well developed. The area of the phytocoenoses of the Rila oak in the three localities is relatively limited.
The trees are of different age. Some of the them are probably more than 200 years old. The diameters of the trees vary considerably, from over 1 m in some trees to only 30 cm in others. Their height also varies: on steep slopes, in secondary ravines it may be over 20 m. The projective cover is about 70–80%, but the trees are spread irregularly. Therefore the horizontal structure, and to a certain extent the floristic composition, of the herbaceous layer vary. As a result of a low fruiting rate or low light, the reproduction potential is low. Single trees, or small groups of young trees 20-30 cm high remain waiting for more favourable conditions to develop. Several other tree species: Acer campestre, A. heldreichii, A. pseudoplatanus, Carpinus betulus, Fagus sylvatica, Fraxinus excelsior, etc. participate as assectators with irregular distribution. Shrub layer is absent, except for the wide distribution of Chamaecytisus absinthioides. Less frequent are Crataegus monogyna, Juniperus communis, Rosa pendulina, Viburnum lantana, etc. The projective cover of the herbaceous layer is 90–95% and is dominated by Poa nemoralis and Brachypodium sylvaticum. Other, less abundant, herbaceous species are Dactylis glomerata, Festuca dalmatica, F. heterophylla, Galium verum, Geranium sanguineum, and Origanum vulgare. More limited is the distribution of Aremonia agrimonoides, Clinopodium vulgare, Digitalis viridiflora, Euphorbia amygdaloides, Pulmonaria obscura, Tanacetum corymbosum, Verbascum abietinum, etc. Apart from the listed species Briza media, Campanula persicifolia, C. rapunculoides, Centaurea triumfettii, Helianthemum nummularium, Hordelymus europaeus, Mycelis muralis, Linaria genistifolia, Prenanthes purpurea, Primula veris, Pteridium aquilinum, Stellaria holostea, Teucrium chamaedrys, Thalictrum minus, Trifolium alpestre, and Viola reichenbachiana also occur occasionally.
The three phytocoenoses are described as association Poo-Qurcetum protoroburoidis, belonging to class Querco-Fagetea and order Fagetalia.
Characteristic taxa.
- Vascular plants: Allium carinatum, Brachypodium sylvaticum, Campanula persicifolia, Coronilla varia, Digitalis viridiflora, Euphorbia amygdaloides, Festuca heterophylla, Geranium sanguineum, Helianthemum nummularium, Mycelis muralis, Poa nemoralis, Primula veris, Quercus protoroburoides, Teucrium chamaedrys, T. montanum, Trifolium alpestre.
Distribution in Bulgaria. Rila Mts – three localities in the valley of Rilska River and its feeder Iliina River.
Conservation importance. There are only three unique phytocoenoses of the Rila endemic Quercus protoroburoides each with very restricted areas of distribution and with the participation of rare species like Lilium martagon, Fritillaria gussichiae, Acer heldreichii.
Threats. Forestry activities. The phytocoenoses in Kalugerski Dol locality on the right slope of the valley of Rilska river is under strong anthropogenic impact. It is close to the path between Ivan Vazov chalet and Rila Monastery.
Conservation measures taken. The habitat is within the borders of Rilski Manastir Nature Park.
Conservation measures needed. Strict protection regime, monitoring of the phytocoenoses.
References. Roussakova & Georgieva 2003.
Author: Veska Roussakova
