And while I was on Westwood I had another visit to that decaying tree that I posted in June. The tree itself didn't appear much changed, it's still hard and not crumbling in any way. I did, however, notice a large number of stinging nettles (Urtica dioica) which weren't there last year. Now nettles like acidic soil but the Westwood sits on chalk which is alkaline, indeed this tree is near Newbegin Pits; the old chalk pits. So looking this up on the web I find, as I vaguely remembered from my student days, that the decay of the tree will produce acids that alter the soil around it. So some subtle changes are happening.