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Deciduous Coniferous

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2012.11.09 Coniferous vs. broadleaf

Idless Wood, Truro

As we stepped out of the car Annie and I were greeted by at least five dogs of varying shapes, sizes, ages and muddiness who were making their way from the gateway into Idless Wood across the car park. Two women followed behind, calling them to their car which was parked next to ours. While they attempted to bundle their entire pack into the boot of a single (Fiesta-ish sized) car, we released Luna from her puppy pen on the back seat. At thirteen weeks old she was tiny in comparison to the aged and well-fed beasts that came enthusiastically to sniff her face (the women were not succeeding in getting them car-bound), but being a whippet she looked extra waif-like next to them. Don’t worry said one of the women as Luna quivered on her skinny legs and tried to get back in the car, when you’re grown up you’ll be able to outrun all of them in a flash.

Idless Wood or St Clement’s Wood, is a Forestry Commission managed patch of broadleaved woodland and larch plantation. On entering by the main path we were met with Forestry Commission signs advising us of their usual tree cutting practices; along another posing the question Why are all the trees dying? Having spent the previous day reading up on Chalara ash dieback I assumed it was more of the same – preventative propaganda, as the disease had not yet been identified in Cornwall. (This was mid November – there has since been one confirmed Chalara infection at a newly planted sight in Cornwall.) The problem at Idless is Phytophthora ramorum, a fungus infecting larch trees.

Larches are grown as a timber crop in plantations all over the UK. They were introduced in the late 19th century and were found to do particularly well as they combined the fast, straight-growing properties of other conifer species like spruce with a tolerance for damp conditions. Larch lap fences were a familiar sight of my childhood as we always seemed to have a spare panel or two leaning up against the house in our side passage. The larch is the only deciduous conifer found in this country. Three types are grown in Britian: Japanese, European and a hybrid of both of these. They now account for about five percent of Britain’s woodlands. Like most trees larches are susceptible to  a number of diseases and fungi – including larch canker, needle cast fungus and larch bark beetle – effects of which can be exacerbated where large, densely planted stands are growing together in plantations as infections can spread quickly between specimens.

Phytophthora ramorum is a recently introduced pathogen sometimes known as ‘sudden oak death’. Initially seen on rhododendrons and other ericaceous plants it was found to be infecting Japanese larches in the South West late in 2009 and has since spread up the west coast to Scotland, and is rapidly heading east. More than 27 hectares of larch have already been felled at Idless Wood alone to try and prevent the disease spreading further. As well as killing the host trees the fungus produces a large number of spores which spread virulently. It is classified as a quarantine disease as it can spread easily on the wind, footwear, car tyres, and also via mist and rain – one wonders if there’s any hope of preventing it spreading with the usual Cornish weather. In some ways the necessary tree felling that is the only way of dealing with infected trees doesn’t seem so bad given that they are a crop species: young specimens which would be felled anyway. The Forestry Commission are looking at restocking options for the gaps left by the excisions at Idless are to replant with mixed broadleaved species, with other areas left to regenerate by themselves.

Some areas of larches remain unaffected here as yet. We forked off the main path and veered down to walk between the larches’ straight and slender trunks. The canopy was dark and high above our heads. Whilst the forest floor of the beech wood section was a crunchy mess of leaf litter and scrambley lower vegetation, here the floor was smooth and springy, only sparsely interspersed with patches of moss. Luna bounded off like a puppy version of Bambi, her tiny feet making a surprising amount of noise. The lack of undergrowth is due to a combination of light deprivation to the forest floor and the acidic humus made of discarded larch needles which makes a nutrient poor substrate. My friend thought she preferred it to the broadleaved areas; admittedly it was easier underfoot but it had a sort of unnatural feeling that in some ways was less outdoors than the other part of the wood, perhaps because of the dense cover roofing us in and the hummocky carpet feeling of the floor beneath.

I was lured back across into the broadleaved section by the autumn colours. Ahead the beech leaves covered the wood floor like copper pennies. The canopy glinted an amber spectrum: green, yellow, gold, orange. Further down-slope, the River Allen flowed along below the path. Luna looked interested and ventured to the edge of the drop that led down to the water, but thought better of going in. A wide, shallow dog wade further down where the path descended to a level with the river gave us the opportunity to discover that whippets aren’t really water dogs. Luna shivered the whole way back to the car. If she wasn’t already blue (dark grey really) to start with she probably would have been after her dip in the river.

At the exit to the wood a tub of dirty water and a scrubbing brush had been set up to encourage us to clean our boots and reduce the chance of spreading P. ramorum spores elsewhere. All very well, I thought, but if it travels so easily on our feet what about the dogs?

 


More on this?

The Forestry Commission have a useful factfile on Phytophthera ramorum and lots of information on other diseases currently affecting the British tree population.

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Author: Merryn

open the curtains and take a look out the window if you want to know what the weather's like

2 thoughts on “Deciduous Coniferous

  1. How interesting! Here in Australia, we have “Jarrah dieback” (Phytophthora cinnamomi), a serious threat to all sorts of native vegetation. I had no idea other countries faced similar problems from different Phytophthora pathogens. I suppose it’s lucky, like you say, that its a plantation and not natural woodland.

    • Yes there are several nasty species in the Phytophthora group – the name is from the Greek for ‘plant destroyer’ which says enough really. Aside from P. ramorum there are four other major Phytophthora fungi wreaking havoc in the UK, though luckily no P.cinnamomi here yet.

      There’s a really informative site you might be interested in http://www.forestphytophthoras.org/

      As to whether it is better that P.ramorum is affecting a crop species in the UK, it is possibly less devastating in that these trees would be harvested anyway at some point, but where the disease has spread up to Scotland the effects of it will be much more of a problem as large tracts of larch monocultural plantations that are pretty much the only woodlands in some areas.

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