Tree Disease and the Cemetery Woodland

Volunteers with Christmas Trees
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November 21, 2019
People walking towards outdoor screening at Arnos Vale
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December 11, 2019

Tree Disease and the Cemetery Woodland

Tree canopy

It’s September 2019 and another sombre report has been added to the already extensive body of research about the decline of nature as a result of human activity. Over half (58%) of Europe’s endemic trees are threatened with extinction, of which 66 species (15%) are critically endangered. A sobering thought that we may lose those beloved trees we grew up with and know so well.

Global trade in plants and wood products have spread far flung pests and diseases to defenceless parks and woodlands, a story so similar to the conquistadors’ cataclysmic eradication of Native Americans that we cannot feign surprise. Compounding the situation are increasing global temperatures and extreme weather symptomatic of a climate crisis caused by our excessive burning of the carbonised remains of trees from epochs ago; our trees’ very own ancestors.

Rarely do declines of obscure insects or scarce mosses get the press they deserve but threatened trees have appeared as the galvanic totem in the fight to conserve nature. Trees are essential for life on earth as we know it, as are insects and mosses, but trees are more to us than this, they have a heightened sense of importance in our collective imagination. Trees are a solid immovable presence standing sentry in our lives, old and wise they seem incorruptible. Yet, in bitter irony the trees’ greatest weakness is us.

Tree disease at Arnos Vale

We are certainly not immune to threat here at Arnos Vale and chief among the exotic pathogens affecting the cemetery is the now well-known ash dieback fungus. With about three quarters of the woodland canopy of the cemetery being ash and an expectation to lose up to 95 per cent in the next decade, the impact on the landscape will be dramatic. However, disease is not a new thing and nature is resilient. If 95 per cent of ash is lost, that leaves 5 per cent to repopulate our woodlands with the next generation of resistant trees. In the mean time the additional dead wood will be a boon to the detritivores and where gaps form other species will be recruited to the canopy leaving a more diverse and healthy woodland.

Tree diseaseFungi on tree

It’s not only novel diseases affecting our cemetery trees either. It is with regret that we will have to remove a significant amount of two of our oldest and dearest trees due to native fungal pathogens, both common on trees reaching the end of their lives. Firstly is the horse chestnut near the Raja tomb which has a sizeable artist bracket fungus slowly eating away at the wood on one side. Despite numerous attempts to reduce the weight in the crown it has come to the point where most of the tree has to be removed to protect people and precious monuments. We will leave 4-5 metres of stem to provide valuable habitat for bats, birds and invertebrates.

It is a similar story with the Himalayan cedar next to the Anglican chapel, although this time the tree is already dead, killed by the aggressive honey fungus. Cedars are particularly susceptible to honey fungus attacks but it is usually only through weakness or old age that the fungus is able to overcome the tree’s natural defences to enter the roots. Again the tree will be ‘monolithed’ to leave a stem that may later be used for a chainsaw sculpture.

The Future

It may seem like we as individuals are helpless in this battle between tree and disease but the future of our woodland depends largely on us. The majority of pests and diseases are brought in from imported plants and wood therefore by ensuring local provenance of these products when we buy them we can limit the global spread. Taking simple biosecurity measures such as cleaning your boots if you’ve worn them outside of your local area can help (see DEFRA advice). Also consider supporting the Woodland Trust in their work campaigning and lobbying government for increased protection of our trees and woodland.

Unfortunately changes to our forested landscape are inevitable and will be dramatic but adopting practices that give nature the space and time it needs to recover is the best chance we have of ensuring a future for our woodland.

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