or Tipitski Lakes. The largest of them is Popovo Lake with 123,600 m2, which makes it Bulgaria's fourth largest glacial lake. With a depth of 29.5 m, it is also Pirin's deepest lake and Bulgaria's second. Situated at an elevation of 2710 m the Upper Polezhan Lake is the highest one in the mountain and in the country. Another remnant from the last Ice Age are two small glaciers. Snezhnika is located in the deep Golemiya Kazan cirque at the steep northern foot of Vihren and is the southernmost glacier in Europe. Banski Suhodol Glacier is larger and situated a bit to the north below Koncheto Ridge. Biology Ecosystems and forests Pirin National Park falls within the Rodope montane mixed forests terrestrial ecoregion of the Palearctic temperate broadleaf and mixed forest. The plant communities in the park can be classified into several main groups: communities found around bodies of water; bush communities of the subalpine zone; grasslands, including meadows, subalpine and alpine pastures; forest communities; rock communities; and communities of secondary character, which are a result of human activity. Forests cover 231.10 km2 or 57.3% of the park's total area. Of them 95% are coniferous forests and 5% are deciduous forests. The mean age of the forest is 85 year. Around 34.3% of the wooded territory is covered with trees above 140 years. The oldest tree in Bulgaria, the 1300–year Baikushev's pine of the species Bosnian pine (Pinus heldreichii), is found in the park and is a contemporary of the foundation of the Bulgarian state in 681 AD. There are 16 tree species; of them three are Balkan endemic taxa with limited areal — the Bulgarian fir (Abies borisii-regis), Macedonian pine (Pinus peuce) and Bosnian pine (Pinus heldreichii). The largest area is occupied by dwarf mountain pine (Pinus mugo) – 59.62 km2, Macedonian pine (Pinus peuce) – 54.15 km2, Norway spruce (Picea abies) – 23.79 km2, European beech (Fagus sylvatica) – 10.98 km2 and Bosnian pine – 8.93 km2. The Macedonian and the Bosnian pines in Pirin National Park constitute respectively 42% and 52% of their total area in Bulgaria. Flora The flora of the park is diverse and is characterized with high endemism due to the combination of southern geographic latitude and high elevational variation. The varied relief creates various ecological environments for plants, further diversified by the dominant rock types which form siliceous and calcareous terrain on the