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Phytophthora Ramorum: Challenges for the Woodland Owner


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About the Author

Marie Ellis Castle Howardblog August 2017Maria Ellis is part of the Forestry Department at the Castle Howard Estate, North Yorkshire. She works closely with the Forestry Manager to ensure the Estate woodlands are managed sustainably across a number of priorities including commercial timber production and sporting pursuits whilst also ensuring that the woodlands archaelogical, ecological and cultural features are protected and enhanced. She has a keen interest in wildlife conservation which she brings to her current role.

Castle Howard is a privately owned estate covering more than 3,500ha of beautiful North Yorkshire countryside. As well as being one of the 10 Treasure Houses of England and a bustling visitor attraction with cafes, a farm shop and a garden centre, it also comprises farmland, a portfolio of residential and commercial properties, a holiday park, a tree nursery and many hectares of woodland. Most of all, Castle Howard is a family home, an important historic landmark and a complex business.

Of the Estate’s total area, approximately 816ha are UK Woodland Assurance Scheme (UKWAS) certified woodland which is managed primarily for commercial timber production but also for sporting, archaeological, ecological and cultural interests. They sit within the Howardian Hills Area of Outstanding Natural Beauty (AONB), a unique and breathtaking area valued for its magnificent landscape, rich wildlife and designated ancient woodland. Castle Howard’s woodlands form an important part of this landscape and are formed of approximately 50% coniferous and 50% deciduous species with the principles being oak, ash, sycamore, Norway spruce, Scots pine and larch.

Pawsreversion Castlehorwardblog1 August 2017 Pawsreversion Castlehoward Vlog3 August2017
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Above: PAWS reversion at Coneysthorpe Banks where larch is being replaced with pendunculate oak, sweet chestnut and sycamore with a percentage of native shrubs such as guelder rose and hazel

Larch has become a great cause for concern for many woodland owners in recent years and it was larch that formed the topic of discussion as Castle Howard welcomed the Royal Forestry Society and its members to the Estate woodlands. The challenges of dealing with a potential outbreak of Phytophthora ramorum are great for any woodland owner but for those private estates that depend upon income from forestry operations to uphold the Estate and secure the future management of the woodland, the challenges are perhaps even greater.

P. ramorum is a fungus-like pathogen that causes widespread fatality amongst larch and can be spread over several miles in watercourses, mists and run off as well as transferred from one site to another by footwear, equipment and animals. As there is no treatment for the infection, once P. ramorum has been identified a statutory felling order is immediately issued. Castle Howard sits within Risk Zone 3 for P. ramorum but with confirmed outbreaks only several miles away the risk increases day by day and with over 150 host species and an ability to switch host plants easily, an eventual infection is almost certain.

The potential consequences of such an infection are huge. Of the total 815ha of Estate woodlands, 170ha are larch and a high concentration of this is situated in Coneysthorpe Banks. At just under 100ha, this is one of the largest blocks of woodland within the Castle Howard Estate and is the key landscape feature of the central basin of the Howardian Hills AONB.

This is particularly worrying, especially if we are to consider that if P. ramorum was identified across Castle Howard woodlands, all 170ha of larch may be lost. The cost of restocking would be extremely expensive and once diseased the larch timber in Coneysthorpe Banks would be worth 25% less than current market value. Even if the Estate was successful in securing the maximum grant available for restocking, losing our larch would have a huge impact on the Estate’s finances and landscape.

There are other, more immediate challenges that P.ramorum has for a private estate. At least 90% of Coneysthorpe Banks are planted ancient woodland sites (PAWS) and, having regretted the decision to clear fell the woodland in the 1950s and replant with conifers, the owner in 2004 was keen to revert the woodland back to native broadleaves – an operation which is continuing today. For a private Estate, balancing conservation and landscape interests with the inevitable need to achieve an economic return is an important, and at times tricky, task particularly when discussing restock plans.

The threat of P. ramorum has recently focused the Estate’s attention on removing all the larch from Coneysthorpe Banks and in order to generate enough economic return to continue the management of these woodlands, the PAWS reversions must be achieved through clear fells rather than thinning. All the Coneysthorpe Banks PAWS are then restocked with pendunculate oak, sweet chestnut and sycamore with a percentage of native shrubs such as guelder rose and hazel. Meanwhile, on non-PAWS, restocking has been agreed at 70% resilient conifer mixes and 30% native broadleaves. This balance aims to achieve a profitable income from soft woods whilst re-creating species-rich native habitats on PAWS.

With P. ramorum on the horizon for many woodland owners, the RFS discussion could not come at a more appropriate time. There will always be interesting and lively debates about how to move forward when faced with situations such as this and in which direction the balance between conservation and economics should swing but by sharing knowledge and expertise with other stakeholders we can all be better prepared for the challenges to come.