The stem oak is the most widespread oak species in Central Europe – but it is very easy to light. Due to increasing drought, trees growing often take the light, so that the oaks can hardly rejuvenate and form healthy offshoots. Tree deaths and additional thinning of the undergrowth can help with rejuvenation, as researchers have now found out. This could even benefit the trees in drought.
Stems grow especially in Au forests- periodically flooded forests on river and baches. By regulating the rivers and changing forest use, these outer forests flood and rarer. As a result, flood -sensitive trees such as Spitzhaorn, Berghaorn and Black elder can grow there, which take the light away from the young oaks. Dürren and pests in turn mean that pointed maple and co die. Researchers around Annalena Lenk from the University of Leipzig have examined whether this will help young handles again.
From “vital” to “normal” and “mickig” to “dead”
In the early 2022, the team created a total of 24 research areas in the Leipzig Auwald, on which they planted a total of 1200 one -year -old handlebars. Eight of the areas had a high tree mortality, eight a healthy tree population and another eight were femal strokes – artificially released clearings. The researchers divided the 24 areas into four parts each, of which they were two sub -growth of Spitzhaorn, mountain hamers and black elder. In addition, they planted 80 genetically identical five -year -old stems to measure the effects of environmental conditions regardless of the genetic influence.
The research team then assessed the vitality of the planted stems planted at the end of May, July and August as “vital”, “normal”, “puny” or “dead” and thus compared their growth success depending on the environment. To do this, they examined the number, size and color of the leaves, dry damage, dead shoots, insect freezing and mildew’s infestation on the oaks. In 2022 dead oaks replaced them in 2023.
High tree mortality and additional thinning
The comparison between August 2022 and August 2023 showed that there was no vital, almost 40 percent of normally grown and about 27 percent dead styles on the areas with only high tree mortality. In comparison, about two percent vitals and almost 63 percent of normally grown oaks grew on additional thinned areas. Almost 20 percent of them were dead. “Forest areas with high tree mortality in the upper class can be used well to promote stem oak rejuvenation-but only if the maple is removed in the shelter,” concludes co-author Christian Wirth from the University of Leipzig. “The maple is available nationwide. Because its growth starts faster, it overgrown and shadows the oaks.” Rejuvenation means the growing up young trees that are supposed to replace the old in the long term and secure the continued existence of Art.
Even more healthy stems grew on the surfaces with a feman strike: in August 2023, 74 percent of the oaks grown normally and only about 17 percent of them died. However, the planted young trees on these areas got along worse with the drought in the summer of 2022, as the examination showed. “Compared to the femula areas, it was shown that the plantings on the upholstery forest areas had to struggle less with dry stress, which was particularly due to the higher humidity,” explains Lenk. “The oaks benefit from increasing light availability [auf Femelflächen]however, this positive connection is weakened by dry stress. “
Nevertheless, this type of forest management could help in the future to rejuvenate stable oak stocks with less regular floods in the au forests to secure their stocks, the team said. This also promotes biodiversity and biodiversity of the forest, since the long -lasting oak habitats are for many insects, birds and fungi. They live in natural tree caves, feed on the acorns of the tree or live under their coarse bark.
Source: University of Leipzig; Specialist articles: Forest Ecology and Management, DOI: 10.1016/J.Foreco.2025.122678