baumzaehlen - Primeval Forests & Their Trees

©2019copyright christoph hase

Cahnov-Soutok National Nature Reserve, Czechia


In Central Europe, the original floodplain forests have been so thoroughly destroyed that this small reserve and nearby Ranšpurk National Nature Reserve on the floodplain of the river Morava are unique for their size and quality1. On a pan-European scale, too, this is one of the most valuable floodplain forest reserves2 although strictly speaking it is no primeval forest (see below), the total area is only 17 ha 3 and it is still divided into two close but separate parts: Cahnov and Soutok4. Thus, the continuous area is actually much lower than the 30 ha estimated for a long-term functioning reserve1.


Selective logging and grazing occurred until 1873 when a definitive ban was put on these activities; after that, there was some local extraction of dead trees from the forest margins for about 60 years 3. There is documented evidence that since the beginning of the 1930s, the locality has been left to spontaneous development, including non-removal of dead wood3.


Mean inundations before the leveeing of the river in 1976 were 50 days per year 5. The leveeing stopped the floods but the flooding was partially restored in 1991 3, nowadays lasting 2–3 weeks per year 4. Nevertheless, the share of fertile flood sediments is now markedly lower as compared with natural floods3. The leveeing and the unnaturally high herbivore populations (see below) have decreased the quality of the reserve1.


Today, the most important tree species by wood volume are Opens internal link in current windowFraxinus angustifolia (narrow-leafed ash) and Opens internal link in current windowQuercus robur (pedunculate oak). The other tree species are Opens internal link in current windowAcer campestre (field maple), Opens internal link in current windowCarpinus betulus (European hornbeam), Opens internal link in current windowTilia cordata (small-leaved linden), Opens internal link in current windowUlmus laevis (European white elm), Opens internal link in current windowAlnus glutinosa (black alder), Opens internal link in current windowCrataegus monogyna (single-seeded hawthorn), Opens internal link in current windowCrataegus laevigata (midland hawthorn), Malus sylvestris (European crab apple), Opens internal link in current windowPyrus communis (wild pear), Populus alba (silver poplar) 3 and Opens internal link in current windowSalix alba (white willow) 6. The floodplain is the northernmost natural occurrence of F. angustifolia 4.


From 1971 the locality was a part of a game enclosure which resulted in reduced or absent natural regeneration over the following 30 years; the core area of Cahnov was fenced only in 2004 leading to a mass regeneration dominated by A. campestre and F. angustifolia, which may be the dominants in the future3. However, wild boars often break through the fence, allowing deer to enter the reserve4. In the period of selective logging before 1873, Q. robur was favoured; today it cannot regenerate due to low light conditions under the canopy, its share decreasing continually3; the dieback of old Q. robur has been accelerated by the cessation of spring floods from 1976 to 1991 7. Dutch elm disease (Ophiostoma novo-ulmi) has caused a dieback of U. laevis 7 and wiped out Opens internal link in current windowU. minor (field elm).


Elevation ranges between 150 and 153 m; mean annual temperature is 9.3°C and mean annual precipitation 517 mm 7.


Ranšpurk Reserve is similar but with denser tree regeneration4. Visiting the reserves needs a special permit.




1       Korpel’, Š. (1995): Die Urwälder der Westkarpaten. Gustav Fischer Verlag.

2       Schnitzler, A. (1994): Conservation of biodiversity in alluvial hardwood forests of the temperate zone. The example of the Rhine valley. For Ecol Manage 68: 385–398.

3       Janik, D. et al. (2008): Opens external link in new windowTree layer dynamics of the Cahnov–Soutok near-natural floodplain forest after 33 years (1973–2006). European Journal of Forest Research 127(4):337–345.

4       Mendel University in Brno, pers. comm. (2016)

5       Penka, M. (1985): Floodplain forest ecosystems I. Academia, Praha.


7       Král. K., McMahon, S. M., Janík, D., Adam, D & Vrska, T. (2014): Opens external link in new windowPatch mosaic of developmental stages in central European natural forests along vegetation gradient. Forest Ecology and Management. 330: 17-28.


Official site:

Fraxinus angustifolia (narrow-leafed ash) along the creek and foreground.
Fraxinus angustifolia (narrow-leafed ash) over the creek; Carpinus betulus (European hornbeam) foliage, right; Tilia cordata (small-leaved linden) foliage, top.
Large fallen Quercus robur (pedunculate oak); Carpinus betulus (European hornbeam), centre and foliage, left; Acer campestre (field maple) foliage, right.
Quercus robur (pedunculate oak); also Acer campestre (field maple, the small tree) and regeneration of A. campestre and Tilia cordata (small-leaved linden).
36.5-metre Fraxinus angustifolia (narrow-leafed ash), centre with top visible. The other large trees are also F. angustifolia. Carpinus betulus (European hornbeam) with dense foliage.
Ulmus laevis (European white elm).
Cahnov forest from a meadow.