G. Forests

Forests of Horse chestnut (Aesculus hippocastanum)

Relationships with habitat classifications. EUNIS: G1.A46221 Balkan Range Horse chestnut ravine forests; PAL. CLASS.: 41.462. Balkan Range Horse chestnut ravine forests; Bondev (1991): 53 Horse chestnut (Aesculeta hippocastani) forests.

Conservation status. BC.

Category. Critically endangered [CR – A1 B2 C3 D3 E3 F3 G3 H3 I L1].

General characteristics. This habitat encompasses the relic mesophytic forests of the Horse chestnut (Aesculus hippocastanum) which have an endemic distribution on the Balkans. There is only one locality of this habitat in Bulgaria – in the Preslavska Mts. of the East Balkan Range. This type of forests belongs to the northern Mediterranean vegetation type and represents the deciduous forests with more southern features that were widely spread in the past. It demonstrates relationships with the forest vegetation in North Greece (Thessaly, Epirus), West Macedonia and Albania, where the remaining localities of Aesculus hippocastanum occur. The communities cover calcareous areas along Dervishka and Lazarska rivers. They occupy the steep slopes of their valleys and make strips of variable density in their most humid parts. The soil is Luvisols, developing on limestone, on which the soil is medium-deep and fresh. It is slightly acidic on the surface and slightly alkaline at depth. Groups of Horse chestnut trees occupy open, rocky steep slopes (25–60°).

The Horse chestnut makes monodominant and mixed communities with 80–90% projective cover of the tree layer. The trees are of different age, the oldest being over 100 years old. The average diameter of the trunks is 35–40 cm, reaching the maximum of 80–90 cm. Seed production is limited and reproduction by shoots prevails.

These communities have been classified only according to the dominant method. The phytocoenosis diversity of the communities is not very high. They belong to three associations from the formation Aesculeta hippocastani, association Aesculus hippocastanum - subnudum, association Aesculus hippocastanum-Carpinus betulus and association Aesculus hippocastanum-Aegopodium podagraria. The first two associations are more widely distributed.

Single trees of Acer platanoides, A. pseudoplatanus, Fagus sylvatica subsp. moesiaca, Juglans regia, Sorbus torminalis, Tilia tomentosa, Ulmus glabra occur in the tree layer of these communities. Cornus mas, C. sanguinea, Corylus avellana, Crataegus monogyna, Staphylea pinnata etc. show high constancy among the shrubs. The herbaceous layer is with low total cover and poor species composition. The spring synusium is represented by Anemone ranunculoides, Corydalis bulbosa, C. solida, Erythronium dens-canis, Isopyrum thalictroides, Scilla bifolia. Anemonia agrimonoides, Dentaria bulbifera, Euphorbia amygdaloides, Mercurialis perennis, Milium effusum, Scilla bifolia, Symphytum tuberosum, Viola reichenbachiana, etc. participate most frequently in the herbaceous layer. The total area of the habitat is approx. 90 decares distributed as follows: Zurleva River locality 14–15 decares, Dervishka River approx. 70 decares, Lozarska River 4 decares and Akandzha River approx 7 trees.

Characteristic taxa.

Distribution in Bulgaria. East Balkan Range, Preslavska Mts., Dervisha locality – along Dervishka and Zurleva rivers; from 300 to 450 m alt.

Conservation importance. The communities have high conservation and scientific importance due to their relic nature and endemic distribution on the Balkans.

Threats. Cutting of the forests in the areas adjacent to the locality and deterioration of the forest microclimate. Cutting and burning of the forests in the past. The plants are attacked by the insect Cameraria ohridella (Lepidoptera - Gracillariidae) that causes complete defoliation of the trees.

Conservation measures taken. The locality is proclaimed as Dervisha Managed Nature Reserve.

Conservation measures needed. Elaboration of a management plan for the Managed Nature Reserve; monitoring, restoration and maintenance activities; assessment of the health status of the chestnut trees, monitoring and limitation of the impact of Cameraria ohridella.

References. Kochev & Gorunova 1972.

Authors: Chavdar Gussev, Vladimir Valchev

Forests of Horse chestnut (Aesculus hippocastanum) (distribution map)