A few years ago, wild trees that would fall down in the park would have been cleared away. At that time the parks were meant to look tidy and well-maintained. Today, there is an increasing interest in facilitating biodiversity in parks and urban green areas. In line with this, the expression of the parks is expanding to include natural and less “manicured” vegetation.
Dead wood is an important habitat for various different species. Therefore, dead wood is preserved in suitable places in the university’s parks, preferably in somewhat secluded areas where there is less traffic.
A dead tree is an ecosystem in and of itself, and houses a variety of fungi, bacteria, insects and mites. These break down the dead wood into nutrients, which again will be absorbed by the vegetation that surrounds it. The decomposition of dead trees is a slow process, taking anywhere from a few decades to several hundred years, depending on the tree species, the size of the tree and the local climactic conditions.
As the wood decomposes, new species emerge while others disappear. Many of the decomposers specialises on certain types of wood, or on wood of specific dimensions.
Dead and hollow trees also play an important role as breeding grounds for insects, birds and mammals. On Blindern, you can find dead wood in the forest grove below the Herb Garden (by Kristine Bonnevie’s hus), in the woodlands by Eilert Sundts hus, and along the path on the east side of T?rteberg.
Hollow oaks
On the university grounds, there are some small, distinctive, areas of untouched nature or remnants of old cultivated landscapes. One such area is a longitudinal, calcareous knoll east of the Chemistry Building. Another is a small oak forest below the Herb Garden by Kristine Bonnevies hus.
Several of the oaks in these two areas are hollow, and thus protected by the Nature Diversity Act. Oaks can become hundreds of years old, and while aging they will house a rich diversity of species. More than 1500 species of insects, fungi and lichens are connected to hollow oaks, including several endangered species. Dead hollow oaks are also protected by the Nature Diversity Act.
In the forest grove by the Herb Garden, there are seven oak trees with a circumference of more than 230 cm. A dead oak on the edge of the forest has been given a strong steel structure to ensure that the tree does not pose any danger to its surroundings. This is one of the few dead, standing and relatively old oaks in Oslo.
The tree is kept standing to facilitate increased diversity of decomposers like fungi, insects and bacteria. Standing dead trees attract other decomposers than dead wood on the ground.