Information on Sirhowy forest work

Find out more about why we have to fell larch trees from the Sirhowy valley

Coronavirus update

We're continuing with our harvesting operations to assist the supply of wood products. Helping to sustain essential services in the health, food and energy sectors.

All of our forestry sites are subject to strict checks to ensure that we are operating within current Government guidelines on coronavirus and social distancing measures.

We remain in close contact with Public Health Wales and will be reviewing our procedures daily in order to keep our staff, contractors, customers and partners safe.


Find out more in our response to the coronavirus pandemic

Updated 10 November 2020

Removal of larch trees

In April, work began to remove approximately 70 hectares of diseased larch trees from the Sirhowy Valley. The trees are infected with phytopthera Ramorum, which is more commonly known as larch disease.

There are approximately 30 hectares of diseased larch trees on the Sirhowy Country Park side of the valley, and approximately 40 hectares on the Cwmfelinfach side.

We anticipate that the work will be finished in December 2020.

Larch disease 

Larch disease, or Phytophthora ramorum, is a fungus-like disease which can cause extensive damage and mortality to a wide range of trees and other plants. Larch disease spreads through airborne spores from tree to tree. It poses no threat to human or animal health. 

Whilst we cannot stop the spread of larch disease, we can take action to slow it down.

In 2013, surveys identified that larch disease was spreading rapidly across forestry in Wales, sparking a nationwide strategy to remove diseased trees to stop it spreading further.

The disease has infected approximately 6.7 million larch trees across the whole of Wales and has had a dramatic impact on our forestry. 

We are legally required to remove infected larch trees under the Statutory Plant Health Notice - Movement (SPHNm) which is issued by Welsh Government. 

Forest access

We do not like to close off access to our forests, which are enjoyed by many, but this is the safest way to allow the work to be undertaken quickly and safely.

We’ve been granted an application to close the foot paths in and around the forestry and will reopen footpaths in certain areas as soon as it is safe to do so. We will keep you informed which section will be re-opened as early as possible via our website and social media channels.

Initially, we anticipate that the operation at Sirhowy Valley will be completed within nine months. 

The forest will become a live operational harvesting site, and areas where the work is being carried out will be clearly sign posted. It is vital that members of the public do not enter these areas for safety reasons.

Working hours

Some of the areas which need felling are in close proximity to people’s houses. In these locations, work will take place between the hours of 8am-6pm. In other areas of the forest, work may begin earlier to maximise progress.

Harvesting and haulage operations

We cannot use modern harvesting machinery due to steep slopes. Timber has to be cut manually and then pulled to the processing and storage site on the road using a ‘Skyline’ winch system. The winch machinery and wire ropes (loaded with several tonnes of whole trees) are positioned upslope and will bring material up to the harvesting machinery for processing, storage in log piles and then loaded onto lorries.

The work will initially begin on the Cwmfelinfach side of the valley. The trees will be transported via our existing private haulage road and the public highway. Our teams are working closely with Caerphilly council to make the routes as low impact as possible

Timber lorries will transport the logs to sawmills in mid-Wales. These sites are specifically licensed to handle timber from infected areas.

Even timber from diseased larch can still be processed and used. After processing it can be used for a number of wood products including building materials, pallets, fencing and wood fuel pellets.

Proceeds from selling the timber

All income from timber sales goes towards the operating costs that we incur through managing the Welsh Government woodland estate. Our costs exceed the revenue generated by timber sales so we also receive additional financial support from Welsh Government. This enables us to continue to provide many free facilities throughout Wales for the benefit of local communities and visitors.

Ground condition

Due to the method of harvesting there will be limited amounts of brash left on the site.

Most of the felling area will be winched to a processing machine situated above the felling area. This tends to lead to a fairly clear site as the brash is left at the top of the site. However depending on the quality of the timber there can be debris left on site. If the timber has been infected with Larch disease for some time, branches/stems can be brittle and break during the winching process.

If there are flat areas these will be harvested by machine. The brash will be laid out in front of the machine to mitigate ground damage cause by impaction. You will be left with rows of brash rows across the site where machine has driven.

The fire risk of the site will be assessed both during and after the operation has been completed.

Nesting birds

Before work began we worked closely with a bird surveyor to thoroughly survey the site for any nesting birds. Any nests that are found will have an exclusion zone put around them and the teams will work around the area until the birds have finished breeding and vacated the nest.

Retaining native broadleaf trees

While we always try to retain as much broadleaf as possible while carrying out harvesting operations, sometimes trees can lose stability after the larch has been removed and become dangerous.

After the larch is removed, remaining large trees which are close to highways or buildings will be surveyed. If they are identified at risk of falling, unfortunately they have to be removed for safety purposes.


We will be replanting over the next three planting seasons, which take place between November and April. The reason we plant in the winter is because we need the trees to become dormant before the nursery can lift and transport the trees for us to plant in our woodlands.

The Sirhowy valley is a Planted Ancient Woodland Site (PAWS) and we will be replanting it with native broadleaves which are more resilient and help secure the site for the future. You can read more about our restocking work in our news section.

Planted Ancient Woodland Sites (PAWS) are sites which are believed to have been continuously wooded for over 400 years and currently have a canopy cover of more than 50 percent non-native conifer tree species. From 2011 5,000ha of Ancient Woodland has been identified on the Welsh Government Woodland Estate that we manage.


We welcome feedback from site users so that we can minimise inconvenience and improve our operations.

If you have any questions you feel are not answered here or would like to give us feedback on our communications, contact us:

General Enquiries:

Telephone: 0300 065 3000 (Mon-Fri, 9am - 5pm) Minicom service: 03702 422 549**