Page 36 - Green knowledge 2024

Photo: Jørund Rolstad
Old trees boost biodiversity
How does the age of trees affect biodiversity in spruce and pine forests? Findings from a
new PhD study reveal that the age of forests and individual trees plays a significant role in
the diversity of lichens, fungi, mosses, and plants.
In his PhD, Eivind Handegard studied how the age of
boreal forests and trees impacts biodiversity. Results
show that older forests and trees are vital for the
diversity of lichens, fungi, mosses, and plants. They
tend to host more species and different types than
younger forests due to many habitats.
Aging makes trees more peculiar; parts of the wood
may die, tree hollows can form, and the bark’s tex-
ture becomes rougher, which benefit several lichen
species. The age of the trees also influences how
many and which lichen species grow on them.
“It’s important to protect large, old trees to preserve
biodiversity,” Dr Handegard explains.
Various features can be used to estimate the age of
old trees, including the bark’s structure and the
shape of the trunk. Previous studies have also shown
other, less visible changes, such as increased stability
due to slowed growth and altered bark chemistry.
Several lichen species thrive particularly well on old
trees.
“Some species are highly specialised and have
adapted to the surface of old trees, such as the stems
of spruce trees,” says Dr Handegard.
On old pine trees, we find the highest number of
lichen species dead branches. The lichens on
spruces, many which are pendulous, respond to both
age and size.
“Lichens take time to grow, and not all of them can
grow on large trees – they need old trees,” says Han-
degard. “In order to protect these lichens, we must
conserve both large and old trees.”
Purpose: Collaboration: Funding: Contact: To investigate how the age of trees affects biodiversity in spruce and pine forests.
Norwegian University of Life Sciences (NMBU)
The Norwegian Forestry Fund, Forestry Value Creation Fund and the Ministry of Agriculture
and Food
Research Scientist Eivind Handegard, Division of Forest and Forest Resources.
Email: eivind.handegard@nibio.no | Phone: +47 452 44 207
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