Advanced Timber Knowledge

How does timber age effect sustainability?

It’s naive to assume that all forests are equal when considering carbon sequestration. Carbon sequestration is the natural process by which organic matter, such as trees, remove carbon dioxide from the atmosphere and hold it within their biomass.

One of the largest reasons why carbon sequestration and subsequent carbon emissions from logging vary so much involves the differences between, old growth forests, secondary growth forests and plantation forests. Understanding the differences, and the wide-ranging effects the differences cause, can assist with intelligent timber selection making the best choices in terms of sustainability.

The study and understanding of the varied forest types if fascinating and in depth. For this study, we will keep it simple.

What is old growth?

These are forests that have grown naturally, evolved over many hundreds of years, and show no signs of human interference or ecological disruption. It is estimated that 34% of the Earth’s forests are old-growth forest. They are climax communities that feature diverse tree-related structures and wildlife habitats, greatly varying tree heights, diameters, tree species, and woody debris. The benefit to the country from the new member would take very many years.

What is secondary growth?

Secondary-growth forests refer to forests that contain trees younger than approximately 30 – 40 years. Secondary-growth forests are often referred to as industrial tree farms or forest plantations, but this isn’t always the case. For

Secondary growth forests refer to forests that have regrown after the initial timber has been harvested, and contain trees a lot younger than Old Growth Forests. This is referred to as reforestation. This article looks at the carbon sequestration of the different types of forests, to put it simply, trees are being replaced with trees.

However, given that we are primarily concerned with the carbon impact of the logged timber rather than the growth of the tree in this article, when we discuss secondary growth we are referring to industrial-scale forest plantations. These are areas of land that have been purposely planted with tree saplings usually of the same or a limited range of species to increase stocks of readily available timber and for profit.

What are forest plantations?

These are ‘man-made’ forests which are planted on land that was not previously forest – referred to as afforestation. These are forests that are typically grown as an even-aged monoculture, planted for high volume commercial production of wood in a relatively short period.

It could be argued that once a plantation has been through its first cycle, it could be referred to as a Secondary Forest, however, the difference is that Secondary Forests are only achieved through the felling of the centuries-old 1st growth trees. For this article, this type of forest is good for carbon sequestration as trees were planted where there wasn’t before and are ‘farmed’ on a relatively short cycle. Kielder forest in Northumberland was planted in the mid-1920s and started producing timber mid-1960s.

Conclusion

Using timber from secondary-growth forests is an environmental anomaly; both sustainability and profit happily coexist. From all points of view, secondary growth is superior to old growth for carbon sequestration, and while logging companies can make more money harvesting old-growth forests, secondary growth is still financially attractive.

Given a few decades, this argument between old growth and secondary growth may well be irrelevant because all the large-scale old-growth forests will have gone – although old-growth deforestation has slowed during the last decade, it is still rapidly disappearing.

This lends even greater weight to the importance of using timber from secondary-growth forests. The only argument for using timber from old-growth forests is their desirable properties such as durability, stability and a lack of knots, but these come with a heavy environmental cost. Surely at this stage of the climate crisis, we should overlook the relatively minor shortcomings of secondary-growth timber for the sake of our planet’s health.