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Living Lightly column

Fallen trees bring life to forest

By Alan Hewett

‘If a tree falls in a forest and no-one is around to hear it, does it make a sound?’ It is a famous philosophical thought but what role does that dead tree really play?

We have heard a lot lately about the amount of debris in our forests. Often when walking in a forest you hear comments about ‘the rubbish’ on the forest floor and how it would look so much better if dead wood were cleared away.

However, fallen timber is vital to the health of a forest. It is estimated that 20 to 40 per cent of organisms in a forest depend in some part of their life cycle on decaying or dead wood.

In fact there is more life in a dead tree than a living one. Studies have shown that a living tree has five per cent living cells by volume while a dead tree has 40 per cent.

The decomposition of dead trees adds nutrients to the soil, especially by slowly releasing nitrogen, helps plants regenerate, reduces erosion and assists drainage and soil moisture. And, most importantly, absorbs carbon from the air.

Dead trees help to maintain a healthy forest and keep it biologically diverse. As well, many species of animals rely on them for survival whether for feeding, breeding, shelter or hibernation. That is why illegal collection of firewood is prohibited.

Microbial organisms and fungi play a vital part in breaking down timber and recycling nutrients to the soil. Very little is known about the role of fungi. The exact number of species is still not known. Some research has shown a symbiotic relationship between fungi and trees in a forest. Trees extract and transfer vital minerals from the fungi into their root systems to enable survival in low nutrient soils.

Fallen logs in waterways provide cover for fish and create pools for spawning. Debris creates dams gathering leaf litter, providing food for fish and invertebrates. By slowing the speed of a stream dead wood reduces soil erosion and regulates flooding.

The next time you walk through a forest don’t just look around to admire the scenery, look down at the dead wood on the ground and appreciate the dynamism going on.

Who knows – you may hear a tree falling in the forest, but hopefully not too close…