Thursday, May 15, 2008

The oak in full leaf with New Forest ponies underneath

The leaves are come now. Over the next few weeks the only changes that will be seen is the slow darkening and toughening of the leaves. Little seedling oaks springing up under the big one, only to be eaten by the caterpillars that fall from the tree canopy when it rains. Acorns that fall rarely live beyond a year. Those that produce oaks are normally transported elsewhere by jays or other birds or animals. Come the middle of August oaks bring out more leaves the "Lamas Growth."

I will try to photograph that and will follow the progress of the oak apples from time to time. See a previous post for more about them. Soon I hope to put up a slideshow of the changes since last October. Meanwhile you can follow other trees in the sister blog Treewatch.

Wednesday, May 7, 2008

The story of the little oak

October lots of leaves but starting to turn

November the leaves are falling

December no leaves, and start of March just a hint of the buds.

The end of April and the beginning of May. The leaves are back.

As well as the big oak I have been taking pictures of another smaller oak (probably about 60 years old and still quite small). These are the pictures from the end of October fully leaved after the summer to the start of May. Fully leaved in new green.

Thursday, May 1, 2008

May Day and Oak apples

First day of May and the leaves are getting thicker. I saw my first New Forest foal this morning. Standing awkwardly on it's four legs, with the legs spread out slightly wider at the bottom. They are tall but very thin and narrow. Didn't get a pic. Let's hope I find one under the tree.

I didn't photograph the foal but I did find an oak apple on a tree where I have been photographing the buds as they develop. Oak apples are the home of the larvae of gall wasps. In spring the gall wasps lay eggs in the leaf buds of oak and some chemical in the eggs causes the oak to develop these protective "apples" where the larvae live and are fed by the oak. Seems a bit improbable doesn't it? ... but you haven't heard the half of it.

This type of gall wasp (there are about a dozen that live on oak trees) is called Biorhiza Pallida. Alternate generations can fly. The flying ones are sexed and the females mate and lay eggs on the roots of oak trees. These eggs cause another type of gall on the roots. Eventually a flightless all-female generation is born from these galls. This generation all crawl up the trees and lays eggs in the leaf buds that cause the oak apples to grow. How did it all start? Which generation came first? You might well ask but don't expect a sensible answer.

Here is a picture of the wasps, presumably the wingless generation on the first and the winged second. These pics are taken from a German beetle site. The first pic is by B Belman and the second by R Werner. The site is:

I shouldn't really have used them but I thought you would like to see the pics

The galls seem to be all over this particular oak. I suppose lots of wasps laid eggs in its roots. It is less healthy than the main oak. I wonder if galls come more on old oaks like ivy. Or if they actually harm the oak. Anyone know?

PS Oak Apple day is May 29 to celebrate the restoration of Charles II who had previously hid in an oak tree at some battle or the other. People wore oak apples.