Ouden J. den, P. Copini & U.G.W. Sass-Klaassen, 2009, Een nieuwe kijk op oude eiken, in: De Levende Natuur, 110, 2
- Author : Ouden J. den, P. Copini & U.G.W. Sass-Klaassen
- Year : 2009
- Title English : A new view on old oaks
- Journal/Series : De Levende Natuur
- Volume Number (ANNUAL: Counting Volumes of the Year shown above) : 2
- Volume Number (CONSECUTIVE: Counting all Volumes of this Journal ever published) : 110
- Pages : 83-87
- Abstract in English : On the sandy areas in The Netherlands, oak trees may grow as clusters of multi-stemmed clones that extend up to 35 m in circumference. The size of these clones suggests a high age of the genetic individual. However, the estimate of age depends on the speed by which the clonal structure expands through time. We investigated how a number of these clusters on Wilde Kamp, a woodland area near Garderen, have originated by vegetative propagation. Under coppice, the tree resprouts each time the stems are cut. Each new sprout grows from the base of the stump, and parts of the lower stem and upper root system die after each coppice cycle. Over time, a stool develops that expands outward. Since this is a slow process, high ages are inferred from large clones. When branches become buried they can build their own root system and grow into independent stems. This layering leaves an unequivocal mark in the tree ring pattern and anatomy of buried stem wood, which can be dated with annual precision. Layering occurs when the base of the tree crown is covered by sand, or when low branches expand horizontally, bend to the ground and then get covered by litter and plants and so become slowly buried. Lateral expansion rate is much higher than in coppice, so large clones may be relatively young. The oak clusters on Wilde Kamp did not grow on an old coppice stool, but the stems were connected by branches that had become underground woody structures after burial. The oldest wood was dated 1826. These clones originated as frequently grazed shrubs in an open habitat. The trees expanded by layering and were cut probably once in the early 20th century. Oak clusters are the legacy of the livestock grazing and open aspect of the woodland landscape.