04F2
Myrtle-leaf rhododendron (Rhododendron myrtifolium) communities
Relationships with habitat classifications. EUNIS: F2.225 Balkan heaths [Rhododendron kotschyi]; PAL. CLASS.: 31.425 Rhodopide and Balkan Kotschy's alpenrose heaths; HD 92/43: 4060 Alpine and boreal heaths; Bondev (1991): 4 Myrtle-leaf rhododendron (Alpine rose) community (Rhododendreta myrtyfolii).
Conservation status. BDA, BC, HD.
Category. Endangered [EN – A1, 2 B1 C3 D2 E2 F2 G2 H2].
General characteristics. Rhododendron myrtifolium is an evergreen shrub, 12–40 cm high. During anthesis in June – July, on the slopes of the mountains the shrubs make a beautiful aspect with their rose-red, infundibular flowers. The phytocoenoses of Rhododendron myrtifolium develop on the rocky terraces of slopes with northern, or predominantly northern exposure, with slope rarely exceeding 30°. They occur mainly between 2000 and 2500 m alt. Localities of up to several tens of square meters also occur rarely at lower altitudes. Near Tuzha chalet in Central Balkan Range such coenoses occur at reaching 1450 m alt. Obviously the distribution of the coenoses in the past was wider. The soils are Lithosols, Leptosols, shallow to medium deep, definitely acidic. Being a relic species in the Bulgarian flora its communities cover small areas. Relatively rarely they are monodominant. Vaccinium uliginosum also occurs in the primary communities. Larger areas are covered by secondary communities of Rhododendron myrtifolium with Juniperus sibirica and a ground layer of Pleurozium schreberi. The communities have rich species composition with well-expressed alpine-subalpine characteristics and considerable participation of diagnostic species from the orders Seslerietalia comosae (Campanula alpina, Cetraria islandica, Deschampsia flexuosa, Festuca airoides, Geum bulgaricum, Homogyne alpina, Juncus trifidus, Potentilla haynaldiana, Sesleria comosa, Veronica bellidioides, etc.)and Vaccinio-Piceetalia (Dicranum scoparium, Hylocomium splendens, Vaccinium myrtillus, V. uliginosum, V. vitis-idaea, etc.). Anthoxanthum ododratum, Avenula vesicolor, Bruckenthalia spiculifolia, Campanula patula subsp. abietina, Geum montanum, Homogyne alpina, Luzula luzuloides, Nardus stricta, Polytrichum juniperinum, Potentilla ternata, etc. also participate in these phytocoenoses. The microthermic and meso-xerophytic alpine, circumpolar and boreal geoelements prevail. The height of the main vegetation layer varies between 20 and 40 cm. The total projective cover most often is 80–100%. The phytocoenoses of Rhododendron myrtifolium are replaced most often by secondary ones of the Siberian juniper (Juniperus sibirica) after anthropogenic impact. In many of them Rhododendron myrtifolium remains as subdominant or assectator.
Bulgaria is the southernmost border of the distribution of Rhododendron myrtifolium. A possible wider distribution of the species in the past was not less than several centuries ago. No data exist about the expansion of the area of the species and its coenoses.
Characteristic taxa.
- Vascular plants: Campanula alpina, Deschampsia flexuosa, Festuca airoides, Geum bulgaricum, Homogyne alpina, Huperzia selago, Juncus trifidus, Luzula luzuloides, Potentilla haynaldiana, Rhododendron myrtifolium (= R. kotschyi), Sesleria comosa, Vaccinium myrtillus, V. vitis-idaea, V. uliginosum, Veronica bellidioides; mosses – Pleurozium schreberi.
- Fungi: Micromycetes – Chrysomyxa ledi (on Rhododendron myrtifolium); Lichens – Cetraria islandica.
Distribution in Bulgaria. Rila Mts. – the northern slope of Belmeken peak and in Central Balkan Range on the northern slopes of Zanogaliiski Chal peak, and less on Yurushka Gramada peak, Severen Dzhendem peak and other neighbouring territories above 1450 m alt.
Conservation importance. Rhododendron myrtifolium is a critically endangered species. The rare species Gentiana frigida participates in its communities.
Threats. Overgrazing, burning of the juniper shrubs in the areas of distribution of the coenoses of Rhododendron myrtifolium; extirpation of shrubs for cultivation by tourists.
Conservation measures taken. The habitat is included in Annex 1 of BDA. The phytocoenoses of Rhododendron myrtifolium are within the borders of Rila and Central Balkan National Parks and in the respective sites of the European Ecological Network NATURA 2000.
Conservation measures needed. Monitoring of the habitat and effective implementation of the regulations related to the national parks.
References. Coldea 1991.
Author: Veska Roussakova
