Old dead wood – What is it good for?

I recall when I supplied my parents’ house with firewood and as far as possible chose dead and dry wood that could be thrown in the boiler the same day. Many do that. The dead and dry wood isn’t worth anything for the industry anyway. However, new times, new methods, new science(?), new thinking … and certification, have changed that. 

Old dead wood – good for the environment

When I learned about Swedish forestry by the end of the ‘70s I was told that the forest should be kept clean. Dead and fallen trees were to be removed from the forest ASAP. The fear of bugs was big, nothing should be left for them. The main reason was to prevent the bark beetle from spreading. But most likely that’s why we have such big problems with the bark beetle today. 

Because when we cleaned the forest of dead trees, the only bugs that had a chance to survive and reproduce were the ones that demand fresh dead wood. That was the only type of dead wood available in the forest (hopefully just for a short while). The rest had been removed. For example, the bark beetle’s enemies, the bugs that demand wood that started to decay, didn’t have anywhere to go for their reproduction. The wood of the following stages of degrading was gone. 

The natural balance had been disturbed

The result after almost 100 years of one-way forest management was that the bark beetle, and some others, could live and breed unthreatened. A long row of bugs and organisms became rare, threatened, and in some cases exterminated. 

On the 29th of December 1993, the convention of biological diversity (CBD) came into force. Today this document has been ratified by 196 nations. Sweden is one of those and a lot has changed in Swedish forestry since then. 

How did Swedish forestry cope with the CBD?

Oh, I remember this. I was a student at the forester school at the time. Suddenly, much of what we had learned up until some weeks earlier was changed. For us students it was interesting and exciting. For the teachers, it was a nightmare just like for the forest industry. 

The Swedish Forestry Act was changed, and the environmental goals became equal to the economic goals. The forest industry asked the environmental movement for help to develop new forest management methods to cope with the challenge. 

When the forest itself decides

Researchers from the forestry business started looking at how the forest “manages” itself. What happens in the forest when humans don’t interfere? An area in northern Russia was found where only a handful of people lived in a forest area of millions of hectares. Here, only one day travel away, the Swedish researchers could see what happens when the forest itself decides. 

The results of this research became the base for the new forest management methods. Easy explained the new methods should as far as possible copy what happens in a natural forest. E.g., a clear-cut could be compared to a wildfire. With the new methods trees and biotopes that normally survive a wildfire should be left untouched during all forestry operations. Old pine trees and wet areas are examples of such biotopes. 

As the Swedish forests were so clean from dead wood it was decided that old dead wood was something that also should be left during all forestry operations. The definition of “old dead wood” is wood/trees that have been dead for at least one year. Fresh dead wood should be removed to avoid bark-beetle attacks. 

Dead stems placed by a wet area where the machines shouldn't go anyway.
Dead stems are placed by a wet area where the machines shouldn’t go anyway.

Dead wood in all stages – What is it good for? 

But also fresh dead wood is needed to create a natural balance in the forest. All stages of dead wood are needed. Therefore, it was also decided that fresh dead wood should be left by making at least three high stumps, 3 – 5 meters (10 – 16 ft) high, per hectare. Furthermore, at least 10 trees per hectare should be left for free development, preferably species that have good chances of surviving storms. By leaving trees and stumps like this for free development all stages of dead wood will eventually be there.

As Norwegian spruce is not among the “storm-safe” species, it should not be left for free development which decreases the risk of creating bark-beetle spreading. 

So, what is it good for? 

What does the dead wood do that makes it so important? The main thing is that it’s rare. Every stage of degrading hosts its special species of flora and fauna. Many of the species are so small that we don’t even see them, but they are still important for maintaining biodiversity. So, creating more dead wood in all stages eventually will bring the balance back and increase biodiversity. But it will take time … 

You may wonder why biodiversity is important. Well, that’s all about a chain reaction. What we eat and live on is in turn dependent on other species, that are dependent on yet another group of species and so on all the way down to the smallest organisms. The more species that disappear, even if it’s far away from us today, the closer we get to eventually having nothing left to live on. 

I’ve said it before, and I say it again: We don’t have to worry about nature. Nature will live on long after the last human has disappeared. It’s for our own sake and future human generations we should care about the environment. 

Protected forest
All stages of dead wood are needed.

Avoid the dead wood in forestry operations

Everyone working in the forest must be educated on environmental issues. Avoiding dead wood is only one piece of action that must be taken in forestry operations in Sweden. 

Machines shouldn’t run over fallen dead trees. Standing dead trees should be left if they are no safety risks. The harvester operator could fall dead trees for safety reasons, preferably with high stumps, and pile them up to avoid disturbing following actions like forwarding and scarifying. Most important is that the old, dry, dead wood stays in the forest and not ends up in a chipper or a firewood pile. 

Nicely piled up by the harvester, out of the way for coming machines.
Nicely piled up by the harvester, out of the way for coming machines.

What about the firewood? 

The most eager environmentalists would say that we shouldn’t use firewood at all as burning it lets the carbon out. A more reasonable way of seeing it is to use fresh wood for firewood but make sure it dries before you burn it. It will take some planning, but it will save the dead wood in the forest and help restore biodiversity. Furthermore, using modern boilers is recommendable as those let a minimum of carbon out into the atmosphere. Efficient burning is a key issue that disqualifies old fireplaces and tiled stoves. 

As for my parent’s house, that now belongs to my sister, it’s equipped with geothermal heating nowadays (installed by the parents before they passed). However, the tiled stoves are still in use … 

Photos: Per Jonsson 

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