In article , Sacha
writes

I'm sure Nick or David will be along to tell us - the autumn colour is
something to do with sugars, IIRC but I find it interesting that the ash
trees have lost their leaves, for example and the oaks and beeches are
holding on to them.

there's a big difference in the times when trees shed their leaves -
whitebeam shed a long time ago, mulberry (which is always very late to
come into leaf) is still in full leaf - though yellow up here. The
sycamores opposite hold on to their leaves much longer than the horse
chestnuts.
--
Kay
"Do not insult the crocodile until you have crossed the river"