Let's talk about 'clearfell' forestry

Updated: Jun 21, 2019

A picture speaks a thousand words.


If you see a photo of a chunk of woodland which has been cut down to stumps, that's a bad thing, right?


Right?


Well, no actually. The practice is known as 'clearfell' forestry and it's one of several techniques used in sustainable forest management around the world. In fact, it's used in forests that are seeing significant net growth.


A paper dedicated to Sustainable Forestry Management, as defined by international protocols such as the Montreal Process and Forest Europe, was included in the supporting documents for a recent study by the UK Committee on Climate Change's report (which found there was scope to increase bioenergy). In its list of sustainable forestry techniques, the first item was clear-felling.


It noted benefits such as:

  • "Clearfell systems work well where growth rates are relatively high and rotations are short." It pointed out that the South East USA (where much of the UK's bioenergy wood pellets originate) has short rotations.

  • "In the UK, clearfell and recently stocked sites provide important habitat for some bird species associated with open space and clear ground..." A similar story is true around the world, with species making use of open ground habitats.


Here's a picture from North Yorkshire in the north of England:


The result of sustainable clearfelling in North Yorkshire, England

The trees have been cut down to stumps across a swathe of woodland. But there are some clues that show this is a sustainable process:

  1. It's been restocked. So this stand will regrow, capture more carbon from the atmosphere and provide wood for timber, bioenergy or whatever else provides a profit for land owners. If left unharvested, growth would slow down and so would the beneficial 'carbon sink' effect. It's a big problem in the UK as we don't have sufficient timber supply chains in place to keep the cycle at an optimum rate, so our woodlands don't do as much carbon sequestration as they could.

  2. There are trees in the background. This tells us it's not a whole forest being chopped down, but one section of one. You can just about see trees in the background at different stages of growth to each other. In fact, to the left of this picture is a stand of trees that are just a few years ahead of the one in the picture, so there are stands of trees in a range of ages across the forest.

  3. New seedlings are planted closer together than the mature stumps. The new seedlings are more densely packed than the big stumps. This is designed to promote tall, straight trees that can be used for high-quality, high-value timber for houses and furniture. That means there'll be a process of thinning every few years to weed out the smaller and misshapen trees that aren't good for timber. These 'thinnings' are one of the key feedstocks for bioenergy because they're considered low-grade wood and unfit for other markets.

  4. Stumps have been left in the ground, which is a key measure used to prevent soil disturbance. Too much soil disturbance can lead to carbon emissions, so it's banned under the international Sustainable Biomass Program, to which all major UK biomass power generators are signed up.

  5. Some 'brash' (twigs, leaves, etc) has been left on the ground, helping to replenish soil nutrients. Not all brash needs to be left and too much can lead to harmful infestations or wildfires. But some is helpful for soil quality.


Now that we know the role of clearfelling in sustainable forest management, let's look at an image presented by the anti-biomass lobby, designed to expose (they're assuming you don't understand forest management) what they call 'deforestation' in the Southern USA:


We agree it isn't 'pretty', but it's still a long-established part of a sustainable forest management system that has seen this area's forest stocks more than double since the 1950s. That's the opposite of 'deforestation'.


The site shown is freshly harvested, so you can't see the restocking about to begin, but this is a requirement for any stands that supply the bioenergy sector. And the figures are clear: the Southern USA is experiencing year-on-year net growth of its working forests:


What you can see in the photo are some of the same sustainability techniques going on as in the North Yorkshire picture. Stumps are still in the ground. Other, less mature stands have been left unharvested. Some brash has been left on the ground.


What you're looking at is a tiny part of a massive landscape where the forests cover land three times the size of the whole UK. Of that area, about 2-4% is harvested each year, while the rest grows and stores carbon in wood that will mostly go to timber, locking up carbon in houses and furniture for years more while new trees grow in their place and continue the process.


Just 0.09% of the forest's standing stock goes into wood pellet exports for the UK and other bioenergy markets. Meanwhile, back in the forest, annual net growth is roughly 0.7-1%, which is why the forests have doubled their standing stocks over 70 years.


So, 'clearfell' forestry is part of a sustainable forest management process. It's true that there is deforestation going on in the world, but it isn't the same everywhere. In the bioenergy sector, strict regulations apply that prevent sourcing from areas that are seeing loss of forest cover. In addition to replacing fossil fuels with a renewable fuel, this means the sector is part of the climate solution, exporting high standards through supply chains around the world.

© 2019 Renewable Energy Association.