2 4 / 2 5 K E Y T O P I C S
The more diverse a forest is, the bet
ter protected it is against climate change. If one tree species disappears, another may take over its function.
But how can foresters influence the mix of tree species in a forest, and to what extent should investments be made in tending a young mixed de ciduous stand?
WSL examined the effective
ness of various tending schemes in a young mixed deciduous forest near Diessenhofen (canton of Thurgau) from 2003 to 2014. The researchers used a sevenhectare area to test three tending options with varying levels of intensity, from extensive tending measures applied across the entire area to an option involv
ing no interventions at all. They marked a total of 480 “future crop trees” – trees with desired charac
teristics – and monitored their de
velopment.
The different tending options had no impact on how well the trees grew. But tree species that are less able to compete, such as oak, dis
appeared more frequently if left un
tended than when competition was kept at bay by removing neighboring trees. The more inten sive the tending measures were, the more admixed deciduous tree species were main
tained, including those able to endure a warmer and dryer climate. (lbo)
www.wsl.ch/more/tending_measures
Photo: Ulrich Wasem, WSL
F O R E S T S
Tending young mixed deciduous forests
promotes tree diversity
A cherry tree whose development the WSL followed on a test area in Diessenhofen (canton of Thurgau) for 11 years.
