Bílá strž National Nature Reserve

The NNR covers the deeply incised valley of the Bílý potok stream in an extensive forested complex on the north-eastern slopes of the Královský hvozd (King’s Forest Ridge) and lies 2 – 3 km south of the village of Hamry within the Šumava Protected Landscape Area.

Parish: Hamry and Hojsova Stráž (Klatovy district)
Area: 79.02 ha
Elevations: 735 – 1086 m
Declared: 1972

The subject of the protection is the north-eastern slopes of the Královský hvozd ridge, into which the upper part of the Bílý potok stream is deeply carved with numerous shelves and rapids and with a 13-metre-high waterfall. The steep slopes are predominantly covered with autochthonous spruce stands.

The rock basement is built of biotite-muscovite mica schists, which also contain intrusions of granite and quartzite veins. The deeply incised Bílý potok valley has an s-shape and the stream falls over numerous rocky outcrops in the form of shelves, rapids and low waterfalls.

Due to the large difference in elevations, the reserve includes stands of herb-rich beechwoods of the Eu-Fagenion alliance and reaches almost to the upper edge of the acidophilous montane beech forests of the Luzulo-Fagion alliance (Calamagrostio villosae-Fagetum association) which cover the largest area. Due to the temperature inversion in the deep, narrow valley the predominant forest type here is stands of autochthonous Norway (Picea abies), with significant numbers of beech (Fagus sylvatica), silver fir (Abies alba) in the admix and rowans (Sorbus aucuparia) in the lower tree level. The oldest tree stands in the NNR are between 220 and 240 years old and are concentrated in small areas around the waterfalls.

Due to the special climatic conditions the herb layer includes species which are typical of the acidophilous montane beechwoods but also from the climax spruce forests which lie above the reserve. Among the most significant herb species we can find holly fern (Blechnum spicant), Alpine sow-thistle (Cicerbita alpina), purple coltsfoot (Homogyne alpina), fir clubmoss (Huperzia selago) and interrupted clubmoss (Lycopodium annotinum).

Vertebrates which are typical of the Šumava mountain range inhabit the NNR territory and notable animals include the raven (Corvus corax), three-toed woodpecker (Picoides tridactylus) and lynx (Lynx lynx) as well as the capercaillie (Tetrao urogallus). Bílá strž is one of the proven localities of the garden dormouse (Eliomys quercinus), and the Ural owl (Strix uralensis) has also been recorded here after it was reintroduced to the Bayerischer National Park across the border in Germany.

In addition to the rugged terrain, the forest stand composition and structure is another characteristic feature of the reserve. The forest stands were probably felled at least once but parts of the stands are certainly of the first generation after primeval forest. The oldest stands have survived around the waterfalls and consist primarily of spruces, some of which reach an average diameter of 95 cm at breast height, along with firs and rowans. Beech trees are only abundant on the left bank of the Bílý potok stream at elevations below 900 metres, whereas they only grow in small numbers in other parts of the reserve. In recent decades the spruces and the firs have rejuvenated naturally in large numbers. At present the forest stands in the reserve are left to natural development processes.

Public access to the NNR is provided along a marked trail and also by a wooden boardwalk which takes visitors down to the waterfall and to the remnants of the oldest forest stands. The Bílá strž ravine is a good example of a forest which was previously exploited by man, cultivated and then left to natural processes. These forest stands document the fact that even in these circumstances, the forest stands have stabilized and moved towards the formation of a mixed age and spatially-differentiated natural forest.