Friday, May 22, 2009

Oak before ash...

Phenology is the study of the times of recurring natural phenomena, as distinct from phrenology which is the study of the relationships between a person's character and the morphology (structure) of their skull, a science which is now completely discredited. Everyone seems interested in phenology these days. Actually I didn't know that was the name for it. But with the interest in climate change, lots of scientists are studying exactly when things in nature are happening. When IS spring?

Well, I want to declare that spring has finally come to Skip. For the years I've been watching - not, I should say, with my pencil and a diary to hand - spring has been when the big beech tree at the bottom of the garden comes into leaf. It seemed slow this year.

My curiosity was aroused. I asked a knowlegeable colleague some questions. Such as, "Why do trees start to go into leaf when they do?" It is forty-five years since I did my botany course at University, and his answers to my questions were somewhat over my head, but I came away remembering the rhyme:

Ash before oak, we’re in for a soak;
Oak before ash, naught but a splash.

There are a number of versions of this old saying which predate the Met Office! I have a number of ash trees in and around the garden. They are always the last to show leaf, while the oaks have been green for ages. It rains a lot in Wamphray, as it is, so if the ash trees were ever to come out early, I'm buying an inflatable!

So let's go back to beech trees.

This was May 8, a couple of weeks ago. Not a leaf in sight. Did you know there is a way of calculating how old a tree is? I don't mean cutting it down and counting the rings. Apparently, you can get a rough idea of a tree's age by measuring its circumference a metre up from the bottom. Dividing the girth in centimetres by 2.5 gives the approximate age. (There are more complicated ways)

This beech tree has a girth of 403 cm, which gives a very approximate age of 160 years. Skip was built 100 years ago. So the tree is older than the house. Indeed on the 19th century map of the area, there is a strip of woodland where the cottage now stands, leading over to the river.

If you are interested in old trees, you will probably already know that there is an effort underway to record the oldest trees in the country, see here.

Interestingly, I took this pic on the same date, May 8. It shows that other beech trees, lining the road near Skip, are already well out.

This was May 11, and the leaves are beginning to show on 'my tree'.

And yesterday, with the leaves out. Phenology - remember the word!

PS. I like this way of measuring the age of trees, taken from the Ancient Tree Hunt website. "Like people, trees grow and age at different rates depending on where they are and what happens to them during their lifetime. But here’s a rough guide to when trees start to be of interest to the Ancient Tree Hunt, based on our hug method of measurement. The 'hug' method for measuring trees. A hug is based on the finger tip to finger tip measurement of an adult, which we take to be about 1.5m. This distance is usually almost the same as your height, and means you can measure a tree even if you forget your tape measure!"

Apparently a very old beech is two adult hugs! So if there is anyone out there who would like to help me measure/hug Wamphray trees.....

No comments:

Post a Comment