Tree felling in Tarn Hows - Q&A

Tarn Hows Autumn woods

We are felling diseased larch trees, to prevent the spread of Phytophthora ramorum, which is a fungus-like virus. It can attack and kill other trees so it is necessary to take action and we are required by law to fell all larch trees within 100m of each infected tree. Parts of the woodland will look quite different for a while. Phytophthora ramorum is not dangerous to humans, dogs or wildlife. But visitors can help to prevent the spread of the disease by staying on marked paths and cleaning mud and needles off boots, (and paws) and pram wheels before they leave.

What is Phytophthora ramorum (Pr.)?
Phytophthora ramorum is a fungus-like pathogen which causes extensive damage and death in a wide range of trees and shrubs.

The disease is known in the USA as 'sudden oak death', but luckily it has little effect on British oak trees. However, larch trees – which are widely grown in the UK for the timber market – are particularly susceptible and large numbers have been affected.  It spreads quickly and easily via spores. Approximately 14% of the woodland here in the south Lakes is larch.

Is it only larch trees which are affected in this woodland?
No, phytophthora can affect a wide variety of trees and shrubs including sweet chestnut, rhododendron and bilberry. It’s particularly important to control larch because of the huge quantity of spores released into the air and the height of the trees means that spores can spread over a wide area.

How do you test for the disease?
Diagnosis begins with a visual inspection by trained observers, followed by field tests on the bark and needles of trees showing symptoms.  It takes 5-10 minutes to indicate whether a phytophthora organism is present in the tree. Laboratory tests are then required to isolate the virus or detect its DNA to confirm the presence of Phytophthora ramorum. 

How did the trees catch the disease?
The first confirmed case of phytophthora in the UK was in 2002. Since then, it’s likely that in many cases the disease has spread to larch trees from Rhododendron ponticum, a common invasive, non-native species present in many British woodlands. Rhododendron is highly susceptible to the disease, and once infected it produces large numbers of spores. The evidence indicates that these spores can be spread over several miles in mists, air currents, watercourses and rainsplash, so, once infected, tall larch trees growing on a wet Cumbrian fellside are an almost perfect way to spread the disease. 

It can also be spread by footwear, dogs' paws, tools, equipment, bicycle and other vehicle wheels. Movement of infected plants is also a key means of spreading it over long distances.  Please clean your boots, bike/pram wheels and paws when you leave Tarn Hows.

Movement over short distances by wild animals such as deer and wild boar might also be possible, although there is little to indicate that small mammals like squirrels transfer the disease from tree to tree.

Are these spores dangerous to humans, dogs or other wildlife?
No.

Why do you have to fell the trees?
When phytophthora is confirmed the landowner (in this case us, the National Trust) is issued with a Statutory Plant Health Notice (SPHN) by the Forestry Commission.  This means that infected, spore producing trees, such as larch, must be felled or otherwise killed as quickly as possible after detection of the disease. If possible, this should be done before the next spring or autumn as during these periods spore production begins on the needles.

Do you have to cut them down? Isn’t there a way to treat the disease?
There is no cure for Phytophthora ramorum and there are no effective chemical treatments available. There are fungicides which can suppress the symptoms, but none which kill the virus.

Why are you cutting them down, when the autumn colours are at their best? 
To comply with the SPHN, to have the felling completed by 31st March 2020, we need to begin felling the larch trees now.  The woodland around the tarn, is only a small part of the 350 hectares covered by the SPHN.

How big is the area in Tarn Hows you must fell?
A 100m circle around each infected tree equates to an area of 3.2 hectares.  We legally have to fell all the larch trees within this area but we can leave the other trees standing. In areas with a lot of infected trees these circles can join together making much larger areas.

Because infected larch trees have been found in numerous places around the Tarn, this area will cover all of the larch directly around the Tarn, on the islands and Iron Keld Plantation visible to the North of the Tarn.

Is it confined to the woodland around the tarn or has it reached other parts of Coniston?
The National Trust had sites infected with phytophthora in 2018 were:  Flemming Wood on the shore of Windermere, Guards Wood, Tarn Hows Wood, Big Wood and one on the shore of Tarn Hows. The larch within the infected areas were felled.

In 2019, there have been more infected trees found in some of the areas in Big Wood not affected last year, Dan Beck Coppice near Outgate, and Tongue Intake. Other private landowners across the Lakes including the Forestry Commission have also been affected.

How long will the felling take?
Infected trees release huge numbers of spores in the spring, so we hope to have all of the larch trees felled by the end of March 2020.

What will happen to the animals living in the trees?
Species like birds and squirrels which can move easily into neighbouring woodland will be less affected. In fact, some species may even benefit from the large open spaces in the woodland.

Will the paths still be open?
We will try to keep paths open, but it will be necessary to close some temporarily during the work for safety reasons. Please follow safety advice on signs around the Tarn.

Visitors can help prevent the spread of disease by keeping to the paths and cleaning boots, bike wheels and paws to prevent the spread of infected material to other sites.

Why is it important visitors keep to paths and clean their boots?
Phytophthora infects the bark and needles; where felling has taken place there will be wood chip and needles on the ground from the forestry operations that can more easily stick to footwear etc. Our foresters will be regularly sweeping the main paths to keep this debris to a minimum. While forestry operations are going on it can be dangerous to walk through the woods off the paths where you may not be visible to our foresters who will be felling trees and operating machinery.

Is there a chance it will spread further once you’ve done all the felling? How will you know it’s all gone?
As the spores travel on the wind there is always a chance the disease will spread but by felling all the larch around the infected trees as quickly as possible we will reduce this risk. The only way to know that the disease has gone is when there are no new cases of trees displaying symptoms.

What happens to all the wood?
The timber can still be used but to minimise the risk of spreading the disease any movement of diseased wood from a forest or woodland to a mill or processing site requires a Forestry Commission movement licence.

Why are so many logs lying around the wood?
We have felled the diseased trees closest to the Tarn, during the least busy visitor time, so as to minimise the essential path closures, thereby maximising visitor enjoyment and safety.
Felling will continue elsewhere throughout the winter but we cannot remove the logs when the ground is so wet, as the machinery needed can damage the ground. 

This is a Site of Special Scientific Interest and the mires are vital to thousands of very important habitats for a whole variety of rare wetland plant species. We hope to remove most of the logs in early spring and will work to minimise the disruption with limited path closures. 

Will you sell the wood?
Yes.  The bark and other infected parts of the tree must be destroyed but the wood can still be used in the timber trade. There are strict bio-security procedures to prevent the spread of disease from infected timber.

Will you plant new trees?
We will establish trees on some of the affected sites by replanting. We will allow glades and denser areas of woodland to develop over the next few decades. We may decide to replant some areas with conifer species. 

Some areas are part of the designed landscape created by James Garth Marshall, we will take this opportunity to reflect on his vision for the site and create a plan that reflects this with our management of these areas.

What will Tarn Hows look like afterwards?
Those areas which were mainly larch, it will look quite bleak.  Other areas which have a variety of tree species won’t look as bare.  We will take some time to monitor and plan what Tarn Hows will look like in the future, keeping in mind that the original Marshall Design had more open space around groups of trees on Tom Heights.  Some of the trees will be replaced but the felled trees may present an opportunity to restore more of Marshalls’ original landscape.

Can anything be done to prevent this from happening again?
Certain types of weather will enable the spores to spread more easily than others – so the warm wet autumn last year is in some parts responsible for the outbreak. By working together with the Forestry Commission and neighbouring woodland owners and getting the infected trees felled as quickly as possible we hope to prevent the spread of the disease in years to come.

Why have some tree trunks been left with spiky tops?
Instead of felling some of the larch we have created some standing deadwood by having the branches cut off and the tops taken out. This kills the tree and prevents the spread of the disease, which needs the needles to release spores from. Standing deadwood is an important habitat feature found in healthy woodland and provides food and shelter for a variety of invertebrates and birds.

How can I help?
All visitors to the countryside can help by staying on marked paths and cleaning mud and needles off their boots, bike or pram wheels and dog paws. As a conservation charity, the National Trust relies upon donations to manage and take care of the land, for nature, the environment and for visitors to enjoy.


If you have any further queries, please email tarnhows@nationaltrust.org.uk