Last year (2013) around September time after the main cut and rake I noticed mounds of grass about 1 foot (30 cm) had been placed round a number of the Celebration Trees. It looked odd, I’d never seen this done before so I went home and had a look on the internet.
I found lots of advice about mulching and how to do it. I found a number of sites and or forums where individuals were asking about using grass as mulch. However, nowhere did I find anything remotely suggesting grass could/should be piled round trees to such a depth. In fact research suggests that too much mulch, of any type, around trees can cause more problems for the tree than any benefits gained.
The grass mounds compacted over the winter, becoming a wet tangled mass. In spring 2014 more grass was piled on top of the rotting mass.
On Sunday 1st June I took my camera round the Pightle. The rotted grass was still present. The grass mound had a firm, dry exterior, but once the top was lifted, the grass underneath was wet and warm; a lot warmer than the surrounding soil. Removal of the rotting grass was accompanied with a fetid smell, much like my old compost bin. Having got some green sludgy goo on my fingers, I located a stick and dug away the grass till I reached ground level. I disturbed numerous ants, a couple of woodlice, spiders and a centipede in the small portion removed.
The tree trunk was visibly damp between the mulch and ground level (see photo above and below), old bark damage was visible, which appeared to be providing hiding/housing for the insects. One of the trees uncovered had plastic wrapped round the bark which I removed; this was also damp. The damage and damp combined could provide optimal conditions for disease and/or further damage.
I only checked the trunks of two of the trees; presumably the others are in a similar condition. Given the warmth emanating, it would have been interesting to have had a temperature reading from within the mounds given that my garden thermometer registered 24 o C in the shade on Sunday.
The Pightle trustees were made aware of the problems that could occur verbally on the 19th May and in writing on the 26th May 2014. The continued presence of the 'mulch' suggests they do not see any issue, however I would suggest that if you have donated a tree, or know of somebody who has donated one, it would be beneficial for you to remove the rotting grass from the actual tree trunk.