Planting trees is a big part of our work to look after rivers. Trees and woodlands provide many benefits including wildlife habitat, carbon capture, improved soil condition, livestock shelter, clean air, reduced flood risk, and cleaner water – as well as being lovely places to visit!
Trees also provide a tasty snack for herbivores, such as voles, hares, sheep and deer, so when we plant trees we need to make sure they are not going to be eaten to the extent that they can’t thrive.
We get a lot of questions about the use of tree guards which is understandable given increased awareness of the issue of plastics in the environment. This page explains our approach to protecting new trees.
One method to prevent browsing (eating of leaves) is to erect fences around the planted area. We make sure there are fences between livestock and planted areas, but deer can jump these stock fences. We could put up 2-metre-high deer fences but this is very expensive and can have a negative impact on the aesthetics and freedom people enjoy on open-access fell sides. These fences also don’t keep out smaller animals such as voles that nibble at the base of newly planted trees. Therefore, a more common approach is to protect each tree with an individual guard.
Most tree guards used today are made from polypropylene plastic. As we become more aware of the problems of plastics and micro plastics in the environment, it might seem counter-intuitive to use a lot of plastic tubes as part of environmental enhancement projects. However, polypropylene is biodegradable and breaks down into carbon dioxide, water, acids and alcohols that don’t have any toxic effects on the environment.
On average, trees need to be in tubes for about five years before they are big enough to withstand browsing pressures. After this time, we we remove the tubes and if they are still in good condition we re-use them. We also remove any empty tubes after the first year. Tree care (also called a ‘beat-up’) to remove tubes and cut back weeds is just as important as planting the trees so we need volunteers to help with this too.
Manufacturers are working hard to produce tree guards made from alternative materials, including recycled cardboard. Until recently, cardboard tubes haven’t been able to withstand the Cumbrian climate and were not cost-effective, but there has been a lot of improvements in their design. We will be trialling these for the next couple of years. We also share best practice and learning with partner organisations including other Rivers Trusts, the Woodland Trust, Cumbria Woodlands and the National Trust who are also working to find and trial alternatives.
Many trees have evolved alongside deer and other herbivores and are resistant to browsing. For some resistant species such as hawthorn, holly and scots pine we don’t need to use tubes. Other species are not resistant to browsing.
We have larger populations of herbivores than would have existed before human settlement, especially sheep and deer, due to agriculture and the loss of predators such as lynx and wolves. We’re not advocating releasing wolves, but this does explain why we can’t just ‘leave things to nature’ and do need to protect trees as they grow.
Some parts of our area do have lower populations of deer than others, or there is more activity to control deer. In these areas we are trialling planting without guards or just with vole guards (10 cm plastic guards at the base of the tree). We’ll keep a close eye on how they grow and which species survive to inform our planting strategy in the future.
Where it is necessary to protect trees with guards, there are also questions about the height of the guard needed. This will depend on the height of the animals eating it. Where there are red deer, 1.8 m tubes are most appropriate for preventing browsing but tall tubes produce tall trees, which isn’t always desirable. On fell sides we are aiming for ‘scattered scrub planting’. This means trees that don’t grow too tall, are less susceptible to wind damage and provide shelter. This is particularly important in the National Park and World Heritage Site due to the visual impact of woodlands. Scrub planting blends in to the surrounding fell creating a mosaic of different habitat, not a stark contrast in the landscape.
There is no right answer on how we should protect trees. Every site has different objectives and constraints that will determine what approach we take. We work closely with the Woodland Trust, landowners and other experts to decide on the best method of planting and protection.