Ash Dieback is the Latest and Potentially the Most Serious Invader from Abroad and Sadly it Won’t be the Last

June 1st 2016

Ash DiebackAccording to government estimates, ash dieback is expected to kill 80 million ash trees over the next 20 years. As a consequence research teams from London and Oxford Universities with the backing of the Department for Environment, Food and Rural Affairs and the Forestry Commission are looking to genetic modification as one of the possible solutions. A GM solution should develop resistance faster than traditional breeding but on the downside it could well face significant public resistance to the use of GM technology. The government have provided a £7 million grant to study ash dieback and to find a viable and publically acceptable solution and also establish a blueprint for dealing with any future threats to UK woodland habitat.

Because of our proximity to the continent Kent’s woodlands are often the first to face the threat caused by such pests. The discovery of the Oriental Gall Wasp in a woodland near Sevenoaks in June was one such example. The larvae of the small wasp causes abnormal growths, called galls to weaken the sweet chestnut tree, making it more susceptible to other pests and diseases. The pest is also parthenogenic, meaning it does not need male wasps to reproduce.

Britain’s suitable climate and the presence of large numbers of its host plant, the sweet chestnut, especially in the south east mean the Oriental Gall Wasp could get established here. Sweet chestnut is highly valued as a timber species and is locally important in Britain, particularly in Kent, where the chestnut coppicing industry has been enjoying a revival in recent years

Luckily even though a second site confirmed the gall wasp was present in a small number of trees in a single street in Hertfordshire no evidence of any other outbreaks have been found.

To date however our solutions have failed to prevent devastating losses to Dutch Elm Disease, the inexorable march of Japanese Knotweed and Himalayan Balsam, the loss of a significant proportion of our bee population to colony collapse disorder and our native White Clawed Crayfish in many streams and rivers through disease spread by the American Signal Crayfish.

What all these sad events have in common is that response has always been reactive and by the time a plan to deal with the threat is in place the invader is firmly established. What we really need is more proactivity looking at potential threats such as a small green beetle called the emerald ash borer in more detail before they arrive on our shore not after the event. Scientists believe the emerald ash borer would be even more devastating than ash dieback if it ever reahed the UK.

After loss of habitat, invasive non-native species is one of the biggest threats to global bio-diversity costing the UK an estimated £1.7billion annually. Against that figure a £7million grant sounds woefully small.

Organisations like ours who spend our time working in ancient woodland to maintain and protect what is left of this beautiful and unique habitat, which once lost can never be replaced, applaud and support the work that is being done but we can’t help feeling that the scale of the threat is not really appreciated and as time passes quickly forgotten. The response is well intentioned but inadequate and slow and the results usually take years to assess often leaving many native species in a greatly diminished state.

Thanks to the work done by organisations like the Joint Nature Conservation Committee the UK is fortunate in having lots of information about its biodiversity, collected across a broad spread of species and habitats both by professionals and by expert amateurs.  This information provides an essential source of evidence for reporting biodiversity change and the impact of policies and actions to conserve biodiversity. The problem we face however is though we score the odd victory overall our resources are simply not equal to the task ahead.