Perućica virgin forest reserve in Sutjeska National Park
In the National Park »Sutjeska« (17,250 ha) the strict forest reserve »Perućica« (1,434 ha) is located. Sutjeska can be found in the southern Dinaric Mountains in Bosnia and Herzegovina, near the border with Montenegro. In this mountainous area altitudes range from 500 m in the Sutjeska river valley to the top of Mount Maglic, 2386 m, the highest peak in Bosnia and Herzegovina. The climate is a mixture of Mediterranean and continental, with high precipitation of 1400 - 2000 mm, depending on altitude and exposition. The Perućica forest reserve mainly lies in the Perućica river basin at the NW slopes of Mount Maglic, between the Sutjeska Canyon at 600 and 1800 m.a.s.l. near Prijevor.
Geology is dominated by limestone on the slopes and cliffs surrounding the reserve and acidic sandstone and shale in the central area. Soils are also diverse and may be derived from a mixture of parent materials, especially were calcareous soils have eroded down slopes. Depending on altitude, slope position and soil conditions different forest associations have developed, different forest associations developed here (more than twenty), ranging from Carpinetum orientalis to Pinetum mughi.
In the lower parts of the reserve, below the Skakavac waterfall, the terrain is very steep. Here at altitudes below 1000 m grow forests of more warmth loving broadleaved trees like eastern hornbeam (Carpinus orientalis), hop-hornbeam (Ostrya carpinifolia), Turkey oak (Quercus cerris), downy oak (Q. pubescens) and other oak species, silver lime and large leaved lime (Tilia tomentosa and T. platyphyllos), manna ash (Fraxinus ornus) and common whitebeam (Sorbus aria). Because of lack of time and the steep terrain alas we did not visit this part of the reserve.
The largest and central part of the reserve, between 1000 and 1600 m.a.s.l. is covered by oldgrowth beech - fir forests, European beech (Fagus sylvatica) and European silver (Abies alba) here dominate heavily. Other species growing here are Norway spruce (Picea abies), sycamore maple (Acer pseudoplatanus), wych elm (Ulmus glabra), European ash (Fraxinus excelsior) and near rivers black alder (Alnus glutinosa). Parts of the forest with deep soils are very dense, with large canopy trees up to over 40 m (broadleaves) and 50 m (conifers) and diameters to over 1 meter. In Perućica the famous Swiss forest researcher Hans Leibundgut in 1954 found a Norway spruce of 63 m tall, the tallest reported of this species in Europe.
We concentrated on this part of the reserve as here most record heights could be expected.
At high outcrops and cliffs black pine (Pinus nigra) is the most important tree but also mountain pine (Pinus mugo) is present. More than 170 species of trees and shrubs and over 1,000 species of herbaceous plants have been registered in Perućica.
Perućica is allowed to enter with a guide only. In the reserve there are no landmines from the the Bosnian War, the only area where they may occur is the lower end of the reserve (in Sutjeska Canyon, near the road). We visited Perućica for two days, led by our guide Vlado (Vladimir) Lalović.
The first day we started with the magnificent view over the Perućica valley with its great forest and the Skakavac waterfal from a ridge near Dragos Sedlo.
The area southeast of Dragos Sedlo and just south of the forest road from Dragos Sedlo to Prijevor was appointed to us by Vlado as the part of the Perućica primeval forest with the largest and tallest trees and the highest volume of the stands, up to more than 1000 cubic metre per hectare.
At a small plot Leibundgut found even as much as 1870 m3/ha of living wood. This forest is dominated by silver fir. Also important are beech and Norway spruce.
Other tree species are scarce, we saw a few wych elms as well as sycamore maples along the road. In this part of the forest also stand the "Three Sisters", a group of Norway spruces said to be the largest and tallest trees in Perucica. Actually, the largest of the three had fallen several years ago. According to the director of the Sutjeska National Park, mr. Zoran Čančar, this tree formerly had a height of 62 m (203 ft) and a diameter of 1.7 m / 5.6 ft (girth 5.34 m / 17.5 ft).
The second tallest Sister had been measured in 2005 and then was 54 m tall with a dbh of 1.55 m. Mr. Čančar ensured us there were no silver firs in the Perucica forest of this size.
The top of the second Sister is now dead and we found the tree only 49.5 m tall with dbh of 1.47 m, but we found several other spruces as well as firs which were larger and taller than the Two Sisters. In this area we found a maximum height of 52.0 m for spruce and even 52.9 m for silver fir and girths up to 5.3 m (17.4 ft) for both species.
Next day we went to the area near the confluence of the Perućica and Prijevorski river (1000 - 1100 m a.s.l.); there we found very tall trees of four species. Most slopes here are facing north to northwest and are relatively cool and moist. There are several sources and small rivers, so the trees have shelter and good water supply.
We found a maximum height of 57.4 m (188.3 ft) for Norway spruce (the second tallest of 56.6 m had a broken top and in the past it may have been a few meters taller) and 54.0 m (177.2 ft) for European silver fir. We think the greater hights here compared to the other area can be explained by the exposition: the area near the forest road is on a slope facing southwest to south while the area with the tallest trees is on a west to north facing slope. The tallest trees we find are nearly always on north facing slopes, while these are cooler and less dry in summer. Additionally, the altitude (around 1400 m) of the area near the road is probably too high for record breaking trees.
In the same area we measured for beech heights up to 44.2 m (145 ft), for sycamore maple to 39 m (128 ft).
Largest trees we saw were the second tallest Norway spruce of 56.6 m (185.7 ft) with cbh of 5.28 m (17.3 ft) and a European silver fir of 52.0 m (170.6 ft) with cbh of 5.26 m (17.26 ft).
The volume of both trees we estimated as around 35 cubic m (over 1200 cubic feet).
We had possibility to explore only a small part of the potential record tree groves, so it is possible larger and taller trees can be found in the forest. To find this out several days of exploration of the forests along the Perućica river and the Prijevorski river from 1600 m downwards to the Skakavac waterfall should be necessary. Very helpful should be if there was done LiDAR research from a small airplane.
A few small clearings are scattered in the forest where localized cutting and grazing occurred in the past, but the influence of these areas on the surrounding stands seems to be rather localized.
Jeroen, Kouta & Michael
Leibundgut, H. (1982). Europäische Urwälder der Bergstufe. Dargestellt für Forstleute, Naturwissenschaftler und Freunde des Waldes. Verlag Paul Haupt, Bern und Stuttgart,
Nagel and Svoboda (2008). Gap disturbance regime in an old-growth Fagus–Abies forest in the Dinaric Mountains, Bosnia-Herzegovina.
Konrad Pintarič. Forestry and forest reserves in Bosnia and Herzegovina.