Sunday, 8 February 2015

Looking At Elms

The Cornfield.
John Constable 1826 showing typical English elms in the landscape
We went to church today.

No, not that church, silly; to the real one where something worthy of praise and adoration lives. We went to the countryside; to the fields, hedgerows and woods where nature lives aloof and indifferent to us; offering no rewards for praise or threats for ignoring it, but deserving love and wonder and protection none-the-less.

We went for a walk in the English countryside on a glorious bright sunny February day with an azure blue Mediterranean sky and birds already staking out their territories and attracting mates with songs and displays. And we saw how natures budges over, accommodates change and carries on. We saw English elm trees in their new guise and role as hedge plants and small thickets for windbreaks and wildlife.

Forgive me if I get a little sentimental here - elm trees were big in my life as a child.

Anyone born after about 1970 in Britain will not remember the giant elm trees that seemed to line every country lane, stand sentinel like guardians round every field and stand solitary or in small clumps in every meadow as shelter for cattle or maybe marking out the line of an ancient hedge now grubbed up and long gone to accommodate the machines that replaced man and horsepower.

When I go back to the small North Oxfordshire hamlet on the banks of the Evenlode where I was born and spent the first 20 years of my life, it now seems open and exposed where once it was wrapped and kept snug by woods of elm in every direction and my whole world was contained in a few water meadows between elm woods beyond which were dragons and people who spoke with strange accents.

On 'our' side of the Oxford to Worcester railway line that ran up the Evenlode valley, there were two huge elms about 40 feet apart and dead in line with the lane I lived in; on the other side of the railway were two more almost exactly the same distance apart. These were almost certainly the last vestiges of a hedge that once ran across a single water meadow before it was cut in two by the railway line and very probably marked an old footpath across to a ford or a bridge over the river where sure enough was the footpath up to the next village. The elms are dead and gone now and not even the roots remain.

Unbelievably, the water meadows have been ploughed up and their ancient topsoil washes into the Evenlode and into the Thames to be dropped as silt somewhere every winter and probably helps parts of Oxford to flood.

Our playground was the 'Big Tree', actually a not so big elm by elmtree standards, but big enough. You came of age as a child when you could reach that first branch and pull yourself up to be with the rest of us as we swung around in the branches and showed off the tricks we had learned or raced to the topmost branch to sway in the wind. If you were too small you swung on the rope with a short branch for a seat or got an older brother or sister to pull you up so you could sit in 'The Saddle' where a branch stuck out from the trunk. We knew every branch and had worn them smooth in places.

I last climbed the Big Tree as a sixteen year-old to nail a bird nest-box high up in its branches for a friend, and elderly retired scientist, in whose garden it had been incorporated when he had his house built on the edge of the village. A new generation of children now played on the swings, slides and roundabout on the village green, paid for by this lovely old professor's wife when she realised we had lost our Big Tree, or stayed in and watched television, and the Big Tree showed few signs of the wear and tear of our generation.

Now these giants are gone. They all went in the 'early autumn' of 1976 when Dutch Elm Disease ravaged the Oxfordshire countryside and most of the rest of England and Wales and giant elms that had stood for centuries withered their leaves and turned brown overnight. And one by one they fell down or were cut down and burned.

But they didn't all die. Some remained as small saplings in hedges, sprouting from the roots of the dead giants and occasionally - very occasionally - from seeds, and even managing to make a few seeds of their own, or put up a few saplings from their own roots before being struck down when about 15 years old, and so they linger on now as a hedging plant in ancient hedgerows.

Tracks of bark beetle larvae beneath the bark of a dead elm.
Photo: Ronnie Nijboer
Dutch Elm Disease (DED) is cause by a fungus of the Ophiostoma genus, usually the virulent Ophiostoma novo-ulmi, which seems to have evolved very recently and which blocks the tree's conductive tissues blocking the flow of sap. It is spread by several species of bark beetle, in Britain usually Scolytus scolytus, the female of which bores a hole through the bark and lays a clutch o of eggs, introducing fungal spores as she does so.

So nature has adjusted and the elm tree, once the giant of the English countryside lives on as a small hedgerow plant. The reason they live for about fifteen years is because it takes them that long to develop a bark thick enough for the bark beetles, which wait until the barks starts to crack to form the typical adult elm bark pattern.

The English elm, Ulmus procera is highly susceptible to DED but is almost entirely dependent on root sucker for its propagation. This fact has enabled it to survive as saplings in hedgerows for forty years since DED hit in full force. There is no magic in this. Given the way both English elms and bark beetles reproduce it was an inevitable result of the presence of the O. novo-ulmi fungus.

Lichen on dead elm sapling
An earlier form of DED, caused by a related fungus, O. ulmi which often only killed a few branches and not the whole tree had invaded Europe in about 1910 but by about 1940 had almost disappeared due to a virus which had evolved to parasitise it. The parasite had itself been killed by a parasite. It's possible that a similar parasite could attack O. novo-ulmi at some point and the English elm can revert back to its earlier form.

Meanwhile, the dead elms provide a nice little niche for other forms of life, such as lichens, brambles and wild roses, perches for buzzards and crows from which to survey their domains, and for woodpeckers to search beneath the peeling bark.

The wonder of nature is how this system works by simple, understandable processes that are always amenable to reason and, when examined are always found to not require magic.

So, we went to a good church today and saw something to marvel at. A few people went to a different one where they shouted down their doubts, pleaded with an invisible omniscient creator to change it's perfect plans, told it how wonderful it is and how disgusting and unworthy they are and, most importantly, begged it to save them from itself.

I think, on the whole, I prefer my church.


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