Friday, 2 May 2014

Thoughts on trees

This week I want to write about evolution. Or, to be more accurate, trees and evolution. At this time of the year, trees demonstrate more than they do another season just how incredibly different they are even though they are all built on the same basic pattern. How did that come about? How could a few differences in the genetic code here and over there result in the sycamore having one sort of leaf and the oak something completely different? Oddly, these two trees do share a common factor: both have buds that are covered by a layer that is opaque. The result is that the new leaves are quite red (I shall be lucky to find good examples because I am a bit late thinking about this but I’ll go out and see what I can find later on). This is because green is the result of the action of sunlight on chlorophyll and, thanks to those opaque bud covers, this cannot start until the leaf emerges. 

Sycamore. The leaves are losing their red tint. The green leaves in the background are, I am sorry to say, common stinging nettles.
Do not touch.
The beech is totally different. Here the bud covers allow the sunlight in and so the leaves are green from the moment the bud bursts: a delicate and very beautiful green.

Beech in all its glory.
Of course when it comes to colour there is probably nothing to beat the maple forests of Canada in the autumn – or fall, if you prefer – a sight I regret I have never seen. Here we have a close relation, the sycamore, but it is a terrible disappointment in autumn. The leaves wither, turn brown and drop. Then, just to add to the mix, there are the evergreens: holly, conifers and so on. As far as leaf colour is concerned these are pretty boring.

I knew it was a bit late to see new oak leaves but here, on this bank beside a lane, there is some that is still quite yellow both in the foreground to the left and further back to the right.
Anyway, why all this? Well it’s all to do with the view from my study window. At The Hermitage there was a deciduous plantation that adjoined the garden and a stand of larch on the other side of the valley. I love the larch which is a wonderful indicator of the seasons with its pale green needles in spring and rich reddy-brown in autumn. Then we moved and I couldn’t see any trees at all. Now we have moved again and there are some really old and magnificent trees in the garden – oaks, beech and ash. My study is upstairs and the garden falls away so it feels as if I am in the treetops. I have been able to watch as they have changed from the gaunt leafless skeletons of winter, through the time when the growing buds and tiny leaflets blur the outline until now when they are fully clothed in their summer foliage. All except the ash tree.

This is the ash tree that stood by the lane just up from The Hermitage. This was taken from the front door.
Have I ever talked about the “sploakometer”? There is an old saying here in England which is talking about when the trees come into leaf: ”ash before oak, in for a soak – oak before ash, in for a splash”. Like so many of these sayings, it does work but only after a fashion. For a start you need an oak and an ash of about the same size and quite close to each other. Then you have to keep your eyes open. Often their leaves come out at more or less the same time – and we have neither a soak nor a splash but something Marcia and I call a “sploak”. Well, we have an ash and an oak of the same size just outside the window here and the oak is in leaf while the ash is not (although there are some smaller saplings that are). It would seem, therefore, that we are in for a dry summer: a splash.

Unless the ash has died.

And here it is again shortly after the snow had melted taken just as the sun was setting. It is a horrid thought that these splendid trees may soon be lost to us (as were the elms not that long ago).
This is a real fear here. “Ash dieback” is caused by a fungus (Chalara fraxinea) which arrived in England a couple of years ago, blown from mainland Europe by the unusually prolonged period of easterly winds we then experienced. Down here in the south west there have been only a few reported cases but in badly effected areas over towards the east this fungus is killing seventy-five per cent of adult trees. Is our big ash tree just biding its time or is it in serious trouble? We shall know in a week or so.
It takes an worried dog to sing a worried song . . . No, that doesn't quite work but you know what I mean. Ben is, what shall I say, anxious. "Am I doing this right?" he seems to be asking.