baumzaehlen - Primeval Forests & Their Trees

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 quality ¹ . On a pan-European scale, too, this is one of the most valuable floodplain forest reserves ² 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 Soutok ⁴ . Thus, the continuous area is actually much lower than the 30 ha estimated for a long-term functioning reserve ¹ .

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 wood ³ .

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 floods ³ . The leveeing and the unnaturally high herbivore populations (see below) have decreased the quality of the reserve ¹ .

Today, the most important tree species by wood volume are Fraxinus angustifolia (narrow-leafed ash ) and Quercus robur (pedunculate oak). The other tree species are Acer campestre (field maple), Carpinus betulus (European hornbeam), Tilia cordata (small-leaved linden), Ulmus laevis (European white elm), Alnus glutinosa (black alder), Crataegus monogyna (single-seeded hawthorn), Crataegus laevigata (midland hawthorn), Malus sylvestris (European crab apple), Pyrus communis (wild pear), Populus alba (silver poplar) ³ and Salix 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 future ³ . However, wild boars often break through the fence, allowing deer to enter the reserve ⁴ . 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 continually ³ ; 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 U. 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 regeneration ⁴ . Visiting the reserves needs a special permit.

References:

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): Tree 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 Úradníček, L., Mendel University in Brno, pers. comm. (2016)

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

6 http://www.cittadella.cz

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

Official site:

http://www.cittadella.cz/europarc/index.php?p=index&site=NPR_cahnov_en