Thinning of old growth forests is not a necessary process for forest health and human safety. In fact, it can be detrimental to the forest in several different ways. As a rule, thinning is used to describe the selective removal of trees from a forest to enable the system to function in better ways such as a greater availability of nutrients; more space available for tree growth; and beneficial impacts on biodiversity.
In Australia, selective removal of trees from forests was widespread, and it was thought that once the forest was thinned, the system would be able to diversify and increase in health because of the loss of an organism that took up much of the available nutrients. Because the soils of Australia are rather nutrient poor, there exists much competition for nutrients. When a tree grows, it takes up many of the nutrients from the soil and stores them inside its cells for use when there is need. Trees are full of many nutrients that other plants use, but exist in a form that other plants cannot reach.
So when a tree is taken out of the system for use as pulp, or as timber, the person taking out that tree is essentially removing a large portion of the nutrients from that system that could have been used by other plants when that tree died and released them back into the environment. There is only a nutrient loss if the forest is thinned.
Many forests are thinned by loggers searching for good timber. They search for the best trees with the finest quality timber on them, and then create a system of roads and other infrastructure near the site to go and extract the trees. This process destroys much of the existing forest. As well the influx of people into the area to get these trees out bring other, more harmful things into the system. Soil-borne diseases like Phytothphora – a hugely problematic fungus that has destroyed many Australian forests today – are brought in with the felling equipment. Seeds of noxious weeds are brought in the same way. How are these things beneficial to forest health?
As for making people safe, such as reducing the risk of fire, and injury from old trees, these are just rumours circulated by the logging companies who have a large vested interest in making the public think that thinning is beneficial, thereby giving the companies more income. In reality, the thinning of a forest has recently been shown in Australia to be false. The issue of cattle grazing in Victoria’s High Country was the vector for this study. It was shown that grazing – the thinning of the forests – did nothing to reduce fuel load, and therefore had nothing to do with fire risk. There was no benefit from thinning.
Forest safety also includes the risk of falling trees and branches onto those people using the forest. The risk of falling branches in an unthinned forest, and a thinned one is virtually the same. There is no difference. Branches and trees fall; it is only a chance event, and unable to be calculated. The trees in Australia are unpredictable; a person could be injured by a branch falling in a thinned forest just as much as they could be in an unthinned forest. It all depends on where a person is; there are walking tracks through forests that are well maintained, and everyone is warned to stick to the paths. If they do so, they should not be harmed by a falling branch or tree except for in extreme circumstances.
The chances of a forest being healthy in the broadest sense of the word is unlikely to happen. It has been shown in many areas that thinning can actually deplete a forests’ health by taking out important factors of the forest community and introducing harmful factors.
