The challenges facing native trees in Sussex
- Credit: Archant
As we enjoy wild flowers in our county’s beautiful woodlands this spring, it’s easy to forget just how many challenges our native trees are facing. Diane Millis investigates.
Sussex has an enviable amount of trees and woods compared to the rest of the country – it’s one of the top three most wooded counties in England, alongside Surrey and Hampshire. But we would do well not to take this bounty for granted. Our woods and trees are facing threats on a scale not seen in living memory.
The numbers of new tree pests and diseases in the UK has grown massively. According to Forestry Commission (FC) figures, there were five outbreaks in 32 years (1970-2002) but there have been 17 outbreaks in just the past 13 years (2003-2016).
One of these outbreaks was the arrival of Chalara, or ash dieback, in 2012. “Ash dieback has largely disappeared from the headlines so it’s easy to think that it has gone away, but it is now found across the UK and will only get worse,” says Dr Matt Elliot, conservation adviser – tree and woodland health at the Woodland Trust.
It had been hoped that British ash trees could prove more able to survive than their Danish counterparts – some 90 per cent of which have been affected – but this is yet to be firmly established. “There does seem to be some tolerance (not immunity or resistance) in some ash trees in the UK but it is too early to say how extensive this tolerance is and whether sufficient tolerant trees survive to allow the ash population to recover. It will perhaps be more than 50 years until we can say,” confirms Dr Elliot.
In Sussex, Chalara is going to have a major impact according to Andy Player, woodland officer for the South Downs National Park Authority (SDNPA). “It will change the face of Sussex and South Downs woodlands – think of the great landscape backdrops to the great estates such as Goodwood and West Dean, which have woods largely comprising ash in places. The public will be able to see the effects, with dead and dying ash trees visible during summer months, and the true extent of the level of damage will continue to show itself over the next couple of summers.”
Meanwhile other pests and diseases are starting to gain a foothold, with the following of particular concern in Sussex:
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• Sweet chestnut blight – an aggressive disease which has recently been found in a small number of sweet chestnut trees in Devon.
• Oak processsionary moth (OPM) – which has spread from London to Surrey, West Berkshire and Hertfordshire (its caterpillars have tiny hairs which can cause nasty skin and eye irritations, sore throats and breathing difficulties in people and animals so it’s also a public health concern). OPM is on the Sussex borders, spreading out from its stronghold in and around London.
• Oriental chestnut gall wasp – which was discovered for the first time in the UK in a woodland in Kent in June 2015 and has since been found in London and south east England.
• Acute oak decline – which is affecting several thousand oak trees, mostly across East Anglia, the Midlands and southern England.
• Red band needle blight – which is often found on pine.
Sussex is home to many forestry businesses that are having to cope with this onslaught.
According to Dougal Driver, CEO of Grown in Britain, pests and diseases already have a significant impact on commercial forests and woods.
“Ash is no longer planted…anywhere,” he says. “Corsican pine, which produces a sought-after construction grade timber, is now no longer a choice for foresters and is being removed from our forests due to red band needle blight.”
“Over time ash dieback will impact both biodiversity in hedgerows and woodlands, roadside tree safety (with the cost implications for making safe) as well as reducing availability of this beautiful white timber and firewood logs,” adds Jamie Kirkman, head forester and sawmill manager for the Balcombe Estate.
“Other threats include red band needle blight in our Corsican pine trees which affects the growth rate of the tree quite considerably, and Phytopthera ramorum which has been detected in some Sussex larch and which also affects rhododendron and sweet chestnut coppice. Larch is an important timber tree for the UK as it is naturally durable and is a great construction material without the need for chemical timber treatment. Sweet chestnut coppice is another source of naturally durable woodland products. Finally acute oak decline is also apparent on several estates, this will have an impact on the green oak timber market.
“Add in the accursed grey squirrel attacking and destroying woodland plantations and our trees face a tough future.”
Others agree that it is the pre-existing pests – namely deer and grey squirrels – that could make all the difference regarding the survival of some of our trees.
“New diseases, combined with the ever present impacts of deer browsing (which reduces natural regeneration), and squirrel bark stripping, means there is a lot of pressure on our woods,” says Andy Player of SDNPA.
“The grey squirrel is a seriously underestimated problem. They may look cute but will damage acres and acres of young trees. Trapping is costly but necessary or we face a bleak future,” adds Jamie.
Meanwhile in the High Weald AONB it is probably deer that represent the biggest threat, according to Matt Pitts, the AONB’s land management adviser. “Our trees are not going to disappear but there will be gaps in the woodland and deer pressure will hamper natural regeneration,” he says.
So what is being done to help our trees and woods? In Sussex, the SDNPA is working on multiple fronts. It is researching tree species that might provide economic, biodiversity and landscape benefits to replace some of those that are being lost, such as Dutch elm disease-resistant cultivars of elm. It is also seeking to help with landscape scale co-ordination of the control of deer.
As Andy says: “The most important defence to any of these threats is to build resilience into our woods, by ensuring that species and age structures are diverse, that woods are well thinned and managed proactively, and that pests and diseases are managed so that our woods are as healthy as they can be”.
Landowners can get support to plant a mix of alternative native broadleaf species via the Woodland Trust in Sussex. It is offering specially tailored Targeting Tree Disease packs, as well as alternative planting schemes at a reduced cost.
Meanwhile, nationally, plant health measures have improved since 2012 and there has been considerable government investment, but more could be done.
“Our reliance on imported plants leaves us open to the arrival of new pests and diseases,” says Dr Elliot of the Woodland Trust. “Opportunities to eradicate pests have been missed in the past and there are nowhere near enough plant health inspectors at our borders.
“We would like to see a more ‘home grown’ nursery system in the UK to lessen our reliance on imported plants. The Woodland Trust stopped importing trees in 2012 and have since introduced a UK Sourced and Grown Assurance Scheme to ensure all of our trees are grown in the UK from UK-sourced seed.”
Despite all these threats, Andy Player of the SDNPA believes there remains a sense of hope for some.
“I think due to national scale news stories around tree diseases, and greater public appreciation of our trees we are in a much better place to combat pests and diseases than even 10 to 15 years ago.”
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