From Keith Alexander, The National Trust
Andy York makes an all too common mistake when he equates rot with ill health in trees
(This Week, 17 October, p 21).
There is an increasing appreciation that heartwood decay is a normal process
in healthy trees. As the girth increases each year, so there is an increasing
volume of heartwood which has no function. The outer ring of the tree is where
everything happens.
Indeed, this dysfunctional heartwood locks up nutrients which the tree could
otherwise reuse and contributes much of the weight of the tree. It was mainly
solid trees which blew down in the hurricane of 1987. Hollowing of the heartwood
by non-pathogenic fungi releases these nutrients and reduces the weight of the
trunk without directly affecting the tree’s health or vitality.
Occasionally, things appear to go wrong and structural defects occur, and, of
course, there are true pathogens about as well. But York is presenting the
foresters’ view. They like their trees solid, but this has nothing to do with
tree health.
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Cirencester, Gloucestershire
