baumzaehlen - Primeval Forests & Their Trees

Dobra Primeval Forest, Austria

Dobra, protected since 1910, is despite its small area (12.3 ha) an important and interesting reserve, for its low elevation, optimal growth conditions and untouchedness¹. The forest was saved because transporting timber from the deep valley was very difficult until about 1970 ¹. No direct human traces can be seen in the forest.

The reserve consists of a northeast–southwest orientated ridge and the adjoining slopes. The northwest-facing slope is very steep, the southeast-facing one less so. Fagus sylvatica (European beech) dominates. Ulmus glabra (wych elm) was until 1974 the second-most abundant tree. At that time, Dutch elm disease (Ophiostoma spp.) reached the locality and the last larger U. glabra trees were infected in 1977 ¹. Even today, young U. glabra can still be found but all the larger trees are gone. Particularly on the ridge there are also Tilia platyphyllos (large-leaved linden). Sambucus nigra (black elder) is abundant as shrubs or small trees. The other, much less common trees are Acer pseudoplatanus (sycamore maple), Acer platanoides (Norway maple), Carpinus betulus (European hornbeam), Fraxinus excelsior (European ash), Picea abies (Norway spruce), Abies alba (European silver fir) and Sorbus aucuparia (European rowan) ^{1 2}. These are easy to distinguish from each other. Conifers P. abies and A. alba are not competitive here². In addition, air pollution has killed the larger A. alba trees³. The lack of large predators has led to roe deer overpopulation, which has a strong effect on tree regeneration and prevents A. pseudoplatanus from replacing U. glabra as a pioneer tree¹. F. sylvatica, instead, regenerates effectively.

On the wind-protected, microclimatically favourable¹ and less steep southeast-facing slope, there are very large F. sylvatica individuals. On the footslope at the eastern end of the reserve, there are also a few very tall F. sylvatica: the tallest tree I measured in 2017 (with TruPulse 200X laser) was 47.4 m, only 1.9 m lower than the tallest reliably measured F. sylvatica ⁴. The tallest tree of Dobra had a girth of only 212 cm. Before the Dutch elm disease, U. glabra reached 154 cm girth ². The high fertility of the soil can be seen, besides the impressive tree growth, from the luxuriant herb layer. On the steep northwest-facing slope the wood volumes and the growth rates are much lower ³. Elevation is 390–550 m, annual precipitation 650 mm and average annual temperature 7°C ¹. The base rock is Gneiss².

References:

1       Mayer, H. & Reimoser, F. (1978): Die Auswirkungen des Ulmensterbens im Buchen-Naturwaldreservat Dobra (Niederösterreichisches Waldviertel). Forstwissenschaftliches Centralblatt 97, 314–21.

2       Mayer, H. (1971): Das Buchen-Naturwaldreservat Dobra/Kampleiten im niederösterreichischen Waldviertel. In Mayer. H. (ed.) 1987: Urwaldreste, Naturwaldreservate und schützenswerte Naturwälder in Österreich. Institut für Waldbau, BOKU.

3       Augustin, B.: Aufbau und waldbauliche Beurteilung des Buchen-Urwaldreservates Dobra II im Kamptal. Diploma thesis, BOKU.

4       http://www.ents-bbs.org/viewtopic.php?f=198&t=5400&p=23625