Pirin National Park (), originally named Vihren National Park, covering the larger part of the Pirin Mountains in southwestern Bulgaria, spanning an area of .

It is one of the three national parks in the country, the others being Rila National Park and Central Balkan National Park. The park was established in 1962 and its territory was expanded several times since then. Pirin National Park was declared a UNESCO World Heritage Site in 1983. The elevation varies from to at Vihren, Bulgaria's second highest summit and the Balkans' third.

The park is situated in Blagoevgrad Province, the nation's southwesternmost region, on the territory of seven municipalities: Bansko, Gotse Delchev, Kresna, Razlog, Sandanski, Simitli, and Strumyani. There are no populated places within its territory. Two nature reserves are located within the boundaries of Pirin National Park: Bayuvi Dupki–Dzhindzhiritsa and Yulen. Bayuvi Dupki–Dzhindzhiritsa is among the oldest in Bulgaria, established in 1934 and is included in the World Network of Biosphere Reserves under the UNESCO Man and Biosphere Programme. The whole territory is part of the network of nature protection areas of the European Union, Natura 2000.

Pirin is renowned for its 118 glacial lakes, the largest and the deepest of them being Popovo Lake. Many of them are situated in cirques. There are also a few small glaciers, such Snezhnika, located in the deep Golemiya Kazan cirque at the steep northern foot of Vihren, and Banski Suhodol. They are the southernmost glaciers in Europe.

Pirin National Park falls within the Rodope montane mixed forests terrestrial ecoregion of the Palearctic temperate broadleaf and mixed forest. Forests cover 57.3 percent of the parks area and almost 95 percent of them are coniferous forests. The average age of the forests is 85 years. Bulgaria's oldest tree, Baikushev's pine, is located in the park. With an approximate age of about 1,300 years, it is a contemporary of the foundation of the Bulgarian state in 681 CE. The fauna of the Pirin National Park is diverse and includes 45 species of mammals, 159 species of birds, 11 species of reptiles, 8 species of amphibia, and 6 species of fish.

History and park administration

Pirin National Park was established on 18 November 1962 in order to preserve the natural ecosystems and landscapes along with their plant and animal communities and habitats. Originally named Vihren National Park, the protected area initially covered 67.36 km2. Its territory was expanded several times until it reached its current area of 403.56 km2 in 1999. In 1983, Pirin National Park was added to the list of UNESCO World Heritage Sites as an area of outstanding natural importance. By the Constitution of Bulgaria, the park is exclusively state-owned.

According to the classification of the International Union for Conservation of Nature the park falls within management category II (national park) with main objective protecting functioning ecosystems while allowing human visitation and its supporting infrastructure. The entire territory of the park is included in the European Union network of nature protection areas Natura 2000. Pirin National Park is listed as an important bird and biodiversity area by BirdLife International.

Pirin National Park is managed by a directorate subordinated to the Ministry of Environment and Water of Bulgaria based in the town of Bansko at the northern foothills of the mountain. As of 2004, the park administration had 92 employees. There are two visitor and information centres located in Bansko and Sandanski. The park is divided in six sectors: Bayuvi Dupki with office in Razlog, Vihren with office in Bansko, Bezbog with office in Dobrinishte, Trite Reki and Kamenitsa, both with office in Sandanski, and Sinanitsa with office in Kresna.

Geography

Overview

Pirin National Park encompasses much of the homonymous mountain range in southwestern Bulgaria, which forms part of the Rila–Rhodope Massif. To the north it is divided from the Rila mountain range by the Predel Saddle and mountain pass at 1140 m elevation, to the east reaches the valley of the river Mesta, including the Razlog Valley, to the south the Paril Saddle (1170 m) forms the border with the Slavyanka mountain range, and to the west reaches the valley of the river Struma. The park is situated entirely in Blagoevgrad Province in the municipalities of Bansko (36.6% of the park's territory), Gotse Delchev (4.9%), Kresna (14.9%), Razlog (10.2%), Sandanski (30.7%), Simitli (2.3%) and Strumyani (0.4%).

Relief and geology The tectonics of the Pirin is primarily the result of Precambrian, Hercynian, alpine and tectonic movements and events. The modern relief of Pirin was shaped in the Pleistocene (2,588,000 to 11,700 years ago) when the mountain was subjected to alpine glaciation related to the global cooling. This glaciation passed in parallel with that of the Alps. The limits of the glaciers reached 2200–2300 m. All glacial forms in the mountain range are within the borders of Pirin National Park.

The Pirin mountain range is divided into three sections: northern, middle and southern, with the northern one being the highest and containing all glacial formations and lakes. The park covers the northern section, itself divided into two zones. The northern zone consists of the steep marble Vihren ridge with the three highest summits in the mountain: Vihren (2914 m), Kutelo (2908 m) and Banski Suhodol (2884 m), as well as the ridge Koncheto (2810 m). The southern zone consists of granite ridges and includes Pirin's fourth highest summit Polezhan, at 2851 m. There are more around 60 summits above 2600 m.

The relief of Pirin National Park is alpine and highly fragmented and is characterized with steep slopes, high ridges and deep river valleys. The highest point is Vihren at an elevation of 2914 m, the second highest summit in Bulgaria and the third one in the Balkan Peninsula, while the lowest elevation in the park is at 950 m near Bansko. Nearly 60% of the park's area is situated above 2000 m. The distribution of the territory of the park by elevation is as follows: up to 1000 m – 1.64 km2 (0.4%), 1000–1600 m – 51.09 km2 (12.7%); 1600–2000 m – 121.08 km2 (30.0%); 2000–2500 m – 198.31 km2 (49.1%); above 2500 m – 31.45 km2 (7.8%). The inclination of the park's territory is steep — more than 90% the total area is classified as steep (21–30°) or very steep (above 31°).

Geologically Pirin is a massive anticline formed by metamorphic rocks — gneiss, biotite and crystalline schists, amphibolite, quartzite and marble. Paleozoic granitoid rocks are found in restricted areas in the outskirts of Pirin National Park. Granitoid rocks from the Upper Cretaceous form two distinct plutons: Northern Pirin and Bezbog. The Central Pirin pluton covers the southern reaches of the park and is dated to the Upper Oligocene. The granitoid rocks cover 55% of the park's territory.

Climate

Pirin falls within the continental Mediterranean climate zone and due to its elevation the higher sectors have Alpine climate. The climate is influenced by Mediterranean cyclones mainly in late autumn and in winter, bringing frequent and high rainfall, and by the Azores anticyclone in summer, making the summer months hot and dry. The relief has a crucial influence on the climate. Pirin has three elevation climate zones — low between 600 and 1000 m (16% of the total area), middle between 1000 and 1800 m (40%) and high above 1800 m (44%). The temperature decreases with the elevation, which is more visible in summer. The mean annual temperature is around 9–10 °C in the lower, 5–7 °C in the middle and 2–3 °C in the higher elevation. The coldest month is January with average temperature varying between −5 and −2 °C. The hottest month is July with temperature averaging 20 °C at 1600 m and 15 °C at 2000 m. Temperature inversions, i.e. increase in temperature with height, are observed in 75% of the winter days.

The annual precipitation is 600–700 mm in the lower elevation zones and 1000–1200 mm in the higher ones. The rainfall occurs mostly in winter and spring, while summer is driest season. The air humidity is 60–75% in August and 80–85 % in December. In winter the precipitation is mainly snow, varying from 70–90% at the lower elevations to 100% at higher. The average number of days with snow cover varies from 20–30 to 120–160. The highest thickness of the snow cover reaches 40–60 cm at 1000–1800 m in February and 160–180 cm above 1800 m in March (190 cm on Vihren). In some winters the snow thickness can reach 250–350 cm. Avalanches occur frequently in winter.

Hydrology

The territory of Pirin National Park is almost equally divided between the basins of the rivers Struma (206.06 km2 or 51.1%) and Mesta (197.50 km2 or 48.9%). The watershed follows the main ridge of the mountain in direction north-west to south-east. Pirin is the source of 10 tributaries to the Struma, the largest one being Sandanska Bistritsa, and another 10 to the Mesta. The rivers are short, steep and with high water volume. They form numerous waterfalls which are generally not as high as those in Rila or the Balkan Mountains. The highest one is Popinolashki waterfall, measuring some 12 m. The average annual discharge of the park's rivers is 355,6 million m3, of them 188,5 million m3 flow to the Struma and 167,1 million m3 to the Mesta. The discharge from the park per square kilometre is 2.3 times larger than Pirin's average and 5.6 times larger than Bulgaria's average.

The landscape is dotted with 118 permanent glacial lakes, conventionally divided into 17 groups, such as Popovo Lakes, Kremenski Lakes, Banderishki Lakes, Vasilashki Lakes, Valyavishki Lakes, Chairski Lakes, Vlahini Lakes 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