Why we fell trees
In 2020 the Scottish Government declared a Climate Emergency. Over the last several years, there’s barely a day goes by when the state of the climate and environment is not in the news. And we all know that trees are a large part of the solution to our over-heating planet. So why on earth would we cut any down?
In this article we’ll look at some of the reasons we fell trees, and show why doing so in the right way is of benefit to combatting the effects of the Climate Emergency.
The Climate Emergency can be simplified to one over-arching problem. This is the vast quantities of gases like carbon dioxide that our modern lives create that, in turn, cause rising global temperatures that are adversely affecting our climate. And, for carbon dioxide at least, nature has given us a ready-made solution: the tree. Trees capture carbon dioxide and produce oxygen which we can breathe. They are the most effective carbon-capturing machine we know of. They’re robust, easily grown, prevalent across the world, and fairly inexpensive. So we come back to the main question: why do we fell trees when they’re so useful? Let’s look at the answers.
When felled, trees can be milled into useable timber that can create any number of materials and products that we find useful. From wood to build a house and furniture, to new discoveries like using chemicals found in trees to make medicines. The uses of a felled tree are vast, and we’re still discovering new uses. The UK imports 80% of its timber needs. By growing the timber for these products here at home, we can reduce the impact on natural forests overseas and reduce costs and emissions from transportation.
If you harvest a tree for timber, you can grow another in the same spot. Other materials like concrete, steel, or plastic cannot be re-grown. Making items from materials like these releases more emissions into the atmosphere, and depletes the earth’s resources. Wood is a renewable resource with a low environmental footprint.
The final part of the timber story is that felling a tree does not necessarily undo the years of carbon-capturing that tree has performed. Carbon is stored in the wood. If you build your house from wood, that carbon will be locked in the timber of your house for as long as the house exists. All the while, another tree is growing on the site of the old one, capturing more carbon.
Using timber in place of other more environmentally damaging materials actively helps our society become more sustainable. This is why a large percentage of forests in Scotland are managed in such a way as to be harvested in the future.
Pests and diseases
With the world becoming increasingly globalised, pests and diseases have been able to spread to new locations. In Scotland, that has caused issues for several species of tree, like pine, larch and ash.
The disease P Ramorum has killed millions of larch trees in Scotland, especially in the south and west. To help contain or slow the spread of this disease we fell infected trees so as to protect other forests. By felling these trees, we can re-plant with different species which will create a new, healthy habitat and start absorbing carbon again. It’s also worth saying that the wood is not wasted when the trees are felled as the timber can be used as normal.
In northern Scotland we have been managing the impact of Dothistroma needle blight on pine. We have removed large areas of infected lodgepole pine, often restoring the ground to peatland. And we have thinned large areas of Scots pine to help improve air circulation and prevent this fungal pathogen from damaging the trees.
In the case of ash, the disease Chalara (Ash Dieback) not only kills the tree but makes it brittle. This poses a risk of falling, whether the whole tree were to collapse or a limb to fall. When next to a path, building or other infrastructure, we monitor carefully and step in to fell the tree if there’s a risk of damage or injury.
Managing pests and diseases is extremely difficult by judicious use of felling and thinning, we try to reduce the impacts that they have, to develop forests that are fit for our future climate.
When initially planted, saplings are small and there may be as many as 3,000 trees per hectare. As they grow, the density means they begin to struggle to all get enough sunlight and nutrients. Thinning involves removing trees to provide more space for the others to thrive. It also lets more light fall to the forest floor, encouraging other species of trees and plant to grow. Thinning happens naturally as the strongest trees outcompete the weakest – and foresters do this using felling, to leave the best trees to grow on to maturity. A forest or stand of trees can be thinned several times over the years at different stages of development.
We don’t thin all our forests, because Scotland is very windy and thinned stands can be more vulnerable to being blown over. But where we can thin, we progressively reduce the density to as low as 100 – 350 per hectare. The trees that are left will be tall, straight and strong.
Plantation forestry is in some ways like farming. When we grow trees for timber, it’s just like planting a crop. The difference is that our crop of trees could take well over 60 years before being ready to harvest. That means we’re managing many forests that were planted throughout the last hundred years.
When the Forestry Commission was established in 1919, the country needed timber. So, land was bought and we planted as many trees as we could. Nowadays, we take a lot more issues into account and deciding where to leave unplanted, and which species should make up our forests, is vital. But we’re still dealing with forests planted purely for timber in years gone by.
One of the biggest issues we have are forests that have been planted on peatlands. Peat, as most gardeners know, is rich and, when drained, great for growing plants and trees. However, peat bogs are a major sink for carbon emissions, and planting on them actually releases carbon dioxide into the atmosphere, despite the trees absorbing some of it in. We now have major projects underway to fell trees from peatlands and restore the peat bogs to their natural state. Doing this has a greater effect on the climate than letting the trees grow on this valuable and unique land.
Sometimes it is necessary to fell trees for the safety of forest users and to protect adjacent amenities like roads or power lines. In the aftermath of strong winds, some trees can be seen to have moved. We want people to visit and enjoy our forests, and that means risks like hanging or weak trees need to be managed, normally by felling.
With infrastructure like roads or power lines, we plan ahead to try and prevent falling trees from causing problems. As an example, the steep hillsides of the A82 by Loch Ness are populated with extremely large Douglas Firs. Some of these magnificent trees are now a potential threat to the road below and the traffic that uses it. If one were to fall onto the road, it could cause significant damage to the road and possibly to road users. That's why we're felling in this area and re-planting the hillside with slow-growing broadleaf trees which will grow without creating the same risk in future.
It's hard to make out, but the image above shows a crack in this trail where the tree roots have moved after high winds. Our team will assess whether it is strong enough to stay standing or may need to be removed for safety.
Put it altogether
We know we need to plant more trees. For Scotland to reach Net Zero, more trees are essential. But it’s important to know that felling and harvesting trees does not counteract this goal, but is consistent with it. Our felling operations touch under 2% of Scotland’s forest cover every year, but provide sustainable materials for many aspects of our lives. The bottom line is that felling trees is, when done in a controlled and considered manner, a vital part of Scotland’s journey to sustainability.