Environment

Richard Nairn: Reflections on Storm Darragh

Shocking though the devastation looked at first sight, I remembered that disturbances from storms like this one are a natural part of the woodland ecosystem

The sacrifice of a few individual trees during a storm is for the common good of the forest. Photograph: Philip Formby/WTML/PA Wire
The sacrifice of a few individual trees during a storm is for the common good of the forest. Photograph: Philip Formby/WTML/PA Wire
Richard Nairn
Sat Dec 28 2024 - 06:00

The wind was howling all night with such ferocity that I thought some slates might lift off the roof. It was enough to wake me several times in the night and then the lights went off. Storm Darragh was the name the meteorologists gave this massive disturbance in the north Atlantic during early December. The radio was giving weather warnings all through the previous day and predicting widespread disruption.

I rose at first light, walked down the meadow and into the wood to check for damage. Leaves and twigs were everywhere on the ground. It was as if the surplus growth of a thousand trees had been discarded, decluttering the canopy and making way for next year’s leaves. As I walked along one woodland path it seemed brighter than usual and then, I noticed it. A giant alder tree has crashed to the ground opening up a great gap in the canopy. Its shattered branches were everywhere, squashing holly trees and blocking the woodland path. I found the place where the tree stood and the reason it had succumbed to the storm. The whole base was rotten in the centre, the heartwood vanished as age overtook it.

As the tree crashed down, the remaining sapwood had ripped apart exposing shredded timber with a deep red colour. I reached my arm right up the centre of the tree. The tops of several ash trees with the dieback disease had been snapped cleanly off leaving standing dead trunks.

Shocking though this devastation looked at first sight, I remembered that disturbances from storms like this one are a natural part of the woodland ecosystem. As a woodland matures, the canopy becomes dense, branches of neighbouring trees touch each other, and the foliage casts a dense shade on the ground below. When a tree falls, a gap opens in the canopy and sunlight pours in. Seeds that have lain dormant begin to germinate and young tree saplings spring into life. It is the way that a woodland naturally grows and the generations of trees replace each other.

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Despite this essential role, fallen timber has been removed from woodlands for thousands of years, usually as fuel, but often just to ‘tidy up’. However, dead or decaying wood may be essential for up to a third of all the species that call a woodland home. It provides a habitat for many species of bryophytes (mosses and liverworts), lichens, fungi, invertebrates, reptiles, birds and mammals. Living veteran trees also provide many important deadwood habitats such as rot holes, hollow heartwood and decaying sap.

I was getting curious now, so I lifted a few dead logs that had been lying on the woodland floor for years. Most had scurrying woodlice, but there were also slugs and snails, centipedes and beetles, tiny mites and spiders. In fact, a whole community was breaking down the decaying cellulose in the timber and returning the nutrients to the woodland soil. There were holes bored in the wood and some of them were occupied by small white grubs. Out of one dead branch ran a beautiful animal called the black-spotted longhorn beetle. I replaced the logs in their original positions and tried to restore the habitats that these creatures need.

The National Survey of Native Woodlands found that twigs and branches on the ground were the most abundant types of dead wood in Irish broadleaf woods. Standing dead or damaged trees were much less common and uprooted and snapped trees were largely rare or absent. Our woodland has plenty of damaged standing trunks and broken branches and these are exploited by birds that nest in cavities, such as the tits and starlings, while the woodpeckers have drilled nest holes in at least four decaying trees. Abandoned nest holes are used as dry roosting places by bats.

Decay in wood is often betrayed by the appearance of fungi on the bark or roots. Most dramatic are the huge bracket fungi that usually grow on the trunks of living trees. However, the underground networks of fungi called ‘mycorrhizas’ are the most amazing features of these organisms. Fungi live around trees and other plant roots and help them to grow by capturing water and nutrients in their vast networks of filaments called mycelia and supplying these to the tree. In return, the trees use the energy of the sun to produce sugars that are used by the fungi.

My initial shock and sadness at witnessing this sudden damage to trees subsided when I realised that there are many benefits for the entire woodland. It is the way that a whole woodland community continues to thrive. The sacrifice of a few individual trees is for the common good. I need to be patient and watch how nature restores the damage.

Richard Nairn is an ecologist and writer. His latest book is Future Wild: Nature Restoration in Ireland