How do we make our forests more resilient?

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When Storm Arwen swept across the UK in November 2021, it produced winds gusting over 90 miles and hour, and led to a rare red weather warning. It caused train lines to shut, left homes and business without power... and flattened huge areas of forest.Forests and woodlands cover around 13% of the UK, and are important for many reasons. They provide timber which is used across the UK for building and construction, they are used by millions of people for leisure and activities, and they are also a habitat for many plants and animals. So when woodland is destroyed, it has far-reaching implications, and Storm Arwen flattened a total area of forest equivalent to 17,000 football pitches in size.This damage was caused by just one, albeit particularly strong, storm. But with climate change, it's likely that the UK will see more frequent, more extreme weather, including storms; we might see more storms, and more stronger storms. These in turn could potentially mean more damage to trees, woodlands and forests. So what can we do about it? How can we make our forests more resilient to storms?

Strength in variety

In the UK, most forests are what's known as commercial forests; trees are grown by the Forestry Commission or other land custodians to produce wood for various purposes, and while those trees are growing, the forests are used for leisure and as wildlife habitats. It's a bit like farming crops, except that the trees take decades to mature before they are ready to harvest.And like crops, most forests are planted with only one type, or several similar types of tree. This tends to be fast-growing varieties of conifer and pine; these are the tall, evergreen trees you often see, growing with long, straight trunks quite close together. The advantage of these species is in the speed at which they grow and those straight trunks, which makes them easy to harvest and cut for building materials. The downside is that they often don't have very deep roots systems to anchor them to the ground, and those evergreen pine needles mean they they are more susceptible to strong winds when the winter storms come through - though they are also very springy and can bend a lot in the wind.When the wind is strong enough, those factors mean that whole areas of trees can fall, taking others down with them as they go.But there is a potential solution, and that is planting a variety of trees. Mixed woodland - where there is a mixture of different types of trees, like conifers, evergreens and deciduous trees like alder, ash and oak - seems to cope better with strong wind conditions. It could be that some of the trees lay down deeper roots, and are more strongly anchored into the ground; these shelter other trees, and are more resistant to being knocked over if a tree falls on them.What's more, these mixed woodlands also seem to be more resistant to other impacts of extreme weather that climate change is likely to bring, such as high temperatures, drought, increased rainfall volume. They can also be more resistant to pests and disease, so it's really a win-win situation.The research was published in journal of the British Ecological Society, and was led by Dr Julien Barrere, a researcher at the French National Research Institute for Agriculture, Food and Environment (INRAE).“An important takeaway from our study is that monocultures of fast growing species such as pine, although valuable from an economic point of view, are more susceptible to storm damage. In a context of increasing storm losses across the continent, our study therefore argues for forest management practices that promote diversity and slow growing tree species such as oak.”As a result of this research, more forestry land management individuals and organisations are starting to look to replant damaged areas, and new forests areas, with a mixture of both the fast-growing conifer species they've always planted, and slower-growing native tree species.

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