News January 2024

How long does a branch remain in the forest?

In Flemish forest reserves, we are witnessing an increase in the amount of dead wood. This is good news for biodiversity and forest health. But for the monitoring that INBO carries out there, it does pose a problem: how to keep measuring all that dead wood in our sample areas on a regular basis? Since 2000, we have already measured more than 12,000 lying logs and branches thicker than 10 cm in the forest reserves.

So we decided not to locate the smaller branches exactly anymore. We determine their volume with a faster, statistical method.

Only branches thicker than 30 cm we still locate so that we can track their change the next time we measure them, 10 years later. In order to determine at what thickness a branch has not yet decayed after 10 years, we looked at repeated measurements of branches of that thickness in our sample areas.

For example, if a branch is 30 cm thick, there is a 50% chance that it is still there after 10 years and has not decayed. Tree species and stage of decomposition also play a role. Large forest giants can remain in the forest for decades, sometimes even more than a century, before they completely disappear.

Arno Thomaes, Peter Van de Kerckhove, Hans Van Calster, Luc De Keersmaeker, Marc Esprit, Stefaan Goessens, Anja Leyman, Kristine Vander Mijnsbrugge, Margot Vanhellemont, Kris Vandekerkhove


Image above: The trunk of large forest giants, such as this recently fallen oak in Wijnendale, can sometimes remain in the forest for over a century (photo Peter Van de Kerckhove)



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