Monday, 11 March 2013

Good news and bad news from Wales

Posted by Dave Lamacraft, Plantlife Cymru Lower Plants Officer

Red eyed shingle lichen - thought, until recently
 to be extinct in Wales. Image © Dave Lamacraft. 
The announcement that three more cases of ash dieback have been discovered in Wales is a poignant counterpoint to the discovery last week of a lichen thought to be extinct in Wales.

The importance of the National Trust's Parc Dolmelynllyn estate (near Dolgellau, Gwynedd), for woodland lichens has been known for some time. In fact it is one of the finest areas south of the Scottish Highlands for the lichens of the 'Celtic rainforest'. Wandering through the woods last week I noticed an ash tree with that indefinable ‘look' about it, something that said “I’m worth a closer look”. It stood on the edge of a glade, was well-lit and mottled with a patchwork of colours from the lichens and mosses covering its bark. It was obviously a special tree; the black smears of the black-bordered shingle lichen were a good sign, but what struck me first was a delicate blue-grey leafy lichen. Although not much larger than a 50 pence piece, the distinctive rusty-red fruits caught my eye. A quick look at Frank Dobson's field guide to British lichens confirmed my suspicions - it was Pannaria rubuginosa, the red-eyed shingle lichen.

Not only is this a most attractive lichen, it was a significant find; it had not been recorded in Wales for almost 50 years and was assumed to be extinct. It was also particularly poignant in a week when another three cases of ash dieback have been found in Wales; as with many of our rarest lichens it was growing on an ash tree. Ash dieback has the potential to devastate our ash trees and the wildlife they support, including many lichens. Some 30% of UK lichens occur on ash - 536 species in all. Of these, 84 are threatened with extinction. It now seems ironic that ash provided an alternative host for lichens affected by the catastrophic decline of elm trees during the 1970s.

With ash dieback in our sights again, the next 12 months will be an opportune time to understand more about the disease and its effects. As well as a halt on the importation and planting of infected ash, we should trial different practical measures to find the best actions for reducing the progression and intensity of the disease. The genetic diversity of our native, non-planted wild ash means that some strains may be less susceptible than others, and observations in Europe suggest that mature trees are more resistant to ash dieback. It could be that widespread felling turns out to be the worst thing to do. We also don't really know how the disease behaves. It could be that ash dieback may spread more rapidly in dense canopies resulting from close planting and a lack of management, in which case thinning and opening up of woodland could be important. This would certainly help other woodland wildlife; flowering plants, birds and butterflies are declining as our under-managed woodland becomes ever darker.

The Chalara Control Plan is about to be published. I really hope this doesn’t ignore the needs of our often overlooked species; the many mosses, liverworts, lichens and invertebrates that depend on our ash trees. The plan needs to set out a sensible, considered, approach for dealing with this disease in the long term, and not be a knee-jerk reaction. As far as we know, a single ash tree is the only home to red-eyed shingle lichen in Wales. It’s a stunning lichen, wonderful to look at like so many in the Celtic rainforest, and I had a real thrill in finding it. I’d dearly like others to be able to experience this too. Yes, we do urgently need a plan, and action, to limit the impact of ash dieback as much as possible, but this has to be the right action; an ill-directed chainsaw could bring about the extinction of red-eyed shingle lichen in Wales in a matter of minutes.

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