ljubljansko barje

The reasons for the founding of Ljubljansko barje nature park

Geographical position
Ljubljansko barje spreads in the southern part of the Ljubljana basin, i.e. between the Ljubljanica river, Vrhnika, Mt. Krim and Škofljica. It covers some 180 m2 and is situated at an altitude of about 130 m. As it lies in tectonically very active area, its origin has been attributed to the sinking of its geological substratum some 2 millions years ago. The depression was simultaneously filled by silt brought by rivers, due to which the Barje is today a large, flat plain with up to 200 m thick layer of alluvial deposits. The sinking, however, is still continuing at a speed of 2 cm/year. Its monotony is here and there broken up by solitary hillocks (built of dolomite), rising up to 50 m above the Barje plain. Ljubljansko barje has continental climate with above average number of foggy days.

The biggest Barje river is the Ljubljanica. It is of karst origin, forming fine material in its water, by which the Barje soil has been coated for millions of years. In most of the cases, these are clayey water-retaining sediments, due to which the area has had, for ages, the character of a wetland.

Some 4,000 years ago, a large shallow lake spread at the Barje. Gradually, however, it was filled up by alluvial deposits and turned into moors with the characteristic form of a raised (peat) bog. No more than two centuries age, a large part of the Barje was covered by peat which, however, was in less than a hundred years cut down and in most cases used as fuel. By attempting to suppress the flooding waters, the first drainage channel was built in 1762, with the draining of the Barje completed with the Gruber Channel built in 1782. Owing to the regularly carried out draining, the greater part of the Barje surface is today a cultural landscape, although with a high groundwater level and regular spring and autumn floods, when even up to half of its surface may be inundated. The annual floods are one of the main characteristics of the area, caused not only by the structure of the ground but also by the local rivers Iščica, Iška, Bistra and Borovniščica, which rise in the southern part of the Barje at the junction of limestones and Barje alluvia and have powerful water-collecting reserves (rain and melting snow), owing to which they quickly spill out of their narrow beds.

In the past, flooding forced the people to settle mostly in higher parts of the Barje as well as on its fringes, whereas the area's draining and new transport links caused, in the early 19th century, the origin of settlements in the very heart of the Barje as well.

In spite of the protracted and persistent endeavours to drain it completely, the Barje remains a wetland, with the water being its basic element. The wetland has a series of significant functions, for it works as a water reservoir (in dry season as well as during the period of surplus water, when by spilling the water across the Barje plain it truly protects the city of Ljubljana from floods) and a natural purifying plant for the greater part of drinking water consumed by the capital's inhabitants. Moisture creates ideal conditions for the origin of huge quantities of green mass, which provides us with oxygen. As wetlands are also the cradle of biodiversity, let us mention that no less than 61% of vulnerable and endangered species and 78% of vulnerable and endangered habitats vitally depend on wetlands. None the less, between 60 and 90% of all former wetlands have been destroyed in Europe, while in Slovenia we are rapidly nearing the figure of 50%.

The moor¸ once prevailing habitat type at the Barje, is more or less the matter of the past, the same as the raised bog, the surfaces with still thick peat substrate that covered the Barje only a couple of centuries ago. Some remains can still be found at Bevke, Črna vas and Kozlarjeva gošča, although they constitute less than 1% of the entire surface area of the Barje.

The habitats, which are increasingly losing their ground, even though they constitute the most precious Barje biotope, are the extensively mown meadows. At the Barje, they still cover 40% of the surface area but are, owing to the increasingly intensive farming (fertilising and early mowing) and urbanisation, from year to year smaller.

The rest of the Barje is covered by fields, rare remains of floodplain forests (Kozlarjeva gošča), and for the agricultural production most suitable Iški vršaj (the triangle Tomišelj, Iška vas, Ig) with its most fertile soil due to its gravely substrate.

Flora and fauna
Ljubljansko barje covers the largest unforested area in Slovenia and has very few suitable comparisons elsewhere in Europe as well. The natural environments, which have evolved in history through natural processes and by the aid of man, today constitute truly exceptional natural riches. The Barje habitats are of crucial significance for the conservation of certain plant and animal species already on the red lists of endangered species in Europe.

The Corn Crake, a grassland bird, is the only globally endangered species that breeds at the Barje. Here nest about 80% of the total Corn Crake population in Slovenia, although in the last five years this once stable population has been cut down almost by half. Corn Crakes nest in extensively farmed meadows, but have been increasingly shifting to the inundated areas at the Barje, as the human pressures there are the least damaging. The greatest threat to this bird is fertilising and early mowing of the meadows, as it breeds at the very time of the first mowing in May. For the conservation of the Corn Crake's habitat, however, mowing is still necessary, considering that the Barje meadows can become completely overgrown with shrubbery in no more than few years. Only ten years ago, another globally endangered bird bred at the Barje, the Lesser Kestrel, which unfortunately cannot be found there any more.

Although the Barje covers only 1% of Slovenia's entire surface area, it must be underlined that owing to its exceptional biotope it is home to even as much as 20% of the population of certain grassland bird species, notably Eurasian Curlew, whose 10 pairs at the Barje constitute the only permanent breeding population in Slovenia. By significantly high numbers, the following species are represented as well: Common Quail, Lapwing, Skylark, Whinchat, Marsh Warbler and Common Kestrel. At the Barje, some endangered forest and marsh birds can be found, too, a total of no less than 107 regularly and periodically breeding species. Still, the area is also significant for the overwintering and migration passages by a series of other bird species.

The wider area of Ljubljansko barje is inhabited by about 45 mammal species, including the highly endangered European Otter, which can be occasionally seen along the Ljubljanica and Iščica rivers. An important segment of the Barje ecosystem are the numerous voles that live exclusively in meadows. The moist Barje soil is not particularly suitable for reptiles, with the European Pond Terrapin, a freshwater turtle adapted to the marshy environment, becoming very rare indeed. Quite different is the case of amphibians (European Tree Frog, Yellow-belied Toad, Edible and Common Frogs) and invertebrates that are still common at the Barje, which is one of the reasons for the diversity and abundance of birds there.

The best represented plant species at the Barje are various meadow plants, gaudily supplemented by the purple Snake's head Fritillary, pink Ragged Robin, yellow Buttercup and Marsh Marigold, and the white Cuckoo Flower. On the remains of raised bog, the endangered species of Peat Moss, Round-leaved Sundew, Mud Sedge and Scotch Heather can also be found.

Prevalent in the overgrown part of the barje are Alder, Oak, Scotch Pine and Birch. Most characteristic here are the never-ending hedges, the up to two metres wide belts of wood vegetation (Alder), which in a similar way as draining channels physically demarcate the plots of different owners and are spread across the entire Barje.