55. Lake Ribno Banderishko, Pirin Mountains (Bulgaria)

The glacial Lake Ribno Banderishko (41° 44ʹ 17.66′′ N, 28° 24ʹ 53.86′′ E; 2190 m above sea level [a.s.l.]) is situated in the subalpine belt of the northern Pirin Mountains. The lake has an elongated shape, 384 m long and 230 m wide, with a water surface of 6.5 ha. The maximum water depth is 14.2 m. The lake is fed by several upper lakes and its watershed is 3.08 km. The slopes are steep and stony, covered by groups of Pinus mugo Turra and Juniperus sibirica Burgsd. within patches of herb vegetation, with the exception of the eastern slope where there is a flat strip 20 m wide (Ivanov 1964). The vegetation comprises several vertical belts. The deciduous forest belt (1000‒1500 m a.s.l.) is fragmented, represented by communities of Fagus sylvatica L., mixed in some areas with Abies alba Mill., Pinus nigra Arnold and Picea abies (L.) Karst. The coniferous forest belt (1500‒2000 m a.s.l.) is well-developed, composed of Pinus sylvestris L., the Balkan endemic Pinus peuce Griseb., Picea abies and the relict communities of the Balkan subendemic Pinus heldreichii H. Christ which occur exclusively on limestone substrates. Stands of Abies alba are also found. The subalpine belt (2000‒ 2500 m a.s.l.) is dominated by thick impenetrable stands of Pinus mugo with Juniperus sibirica and Vaccinium myrtillus L. A characteristic feature of the modern vegetation is the presence of a large group of Balkan and Bulgarian endemics, including 30 local endemics (Tonkov et al. 2002). The Pirin Mountains are a large anticline, its granite centre overlain by Palaeozoic metamorphic rocks. The northern part, which was glaciated during the Quaternary occupies 74% of the total area and is composed of granite, crystalline schist and marble (Galabov et al. 1977). Above 1000 m a.s.l. the climate is typically montane and the annual amount of precipitation is 800‒1250 mm with a maximum in November–December, much of which is snow above 1500 m a.s.l. (Tishkov 1976).