Gathering knowledge about old trees

Old trees in the forest serve as vital habitats for many birds, insects, lichens, and mosses, thus playing a significant role in the biological diversity of the forest. However, there is relatively little research on how the composition of species changes as trees age. How many more rare species exist in ecosystems associated with old trees? And do we actually know where the oldest trees in Norway grow? They might not necessarily be the tallest or largest. Some trees may have grown slowly throughout their entire lifespan or remained suppressed in the forest when young.

This information is important because it informs us about the age of the forest when deciding what can be harvested and what should be preserved.

These are questions that concern Eivind Handegard. He is a PhD student at the Norwegian University of Life Sciences (NMBU) and NIBIO, with a specialisation in old trees. In his doctoral work, he addresses some of the knowledge gaps related to old forests.

"How long does it take for different species to appear? How significant is the difference between younger and older trees? These are some of the questions I am trying to find answers to. I particularly study different species of mosses and lichens on trees, saprotrophic fungi on deadwood, ground-dwelling plants in the forest floor, and mosses and lichens on rocks," he says.

Handegard explains that, in general, old forests tend to have more variation in biodiversity because there are usually more old trees, trees of different sizes, clearings, and, not least, deadwood. Deadwood is an important habitat for several forest species, ranging from insects and fungi to various types of lichens. Standing deadwood, for example, becomes a home for cavity-nesting birds such as woodpeckers and owls.