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Wood Decay and Timber - Part 1

Over on one of my recent Instagram posts, we had a bit of a discussion about how fungi can affect trees, and create some amazing colouration and patterns in the timber. Since then I've had some questions about the topic so thought I'd put together a couple of blog posts on it!

Polyporus squamosus, otherwise known as Dryad's Saddle, is a fungus that forms in clusters and tiers on broad-leaved trees with the fruiting bodies appearing in summer and autumn. Although edible the fungus does not last long as insects quickly devour these large brackets, and in warm weather they can decay from full splendour to almost nothing in just a few days. Numerous insects will also lay their eggs inside the fungus acting as food for the larvae.

The fungus not only parasites standing timber but also occurs on fallen and felled timber. It is commonly found growing on broadleaved trees across Europe and North America and can be regularly found on dead and dying Beech, Ash and Sycamore trees. Interestingly though, 'Dryad' is a mythical wood-nymph inhabiting oak trees!

Dryad's Saddle is a white rot and causes heart rot to the stem and branches. The wood can, at first, become brittle and then soft forming cavities along the stem and branches. Some white rot fungi destroy both lignin and cellulose, leaving wood in a moist, soft, and sponge-like structure with a pure white or yellowy colour. Others attack the lignin, using powerful enzymes like laccase making them known as lignin-modifying enzymes. Some of these enzymes are even potent enough to oxidise lignin.

If you're interested in wood-destroying (or enhancing?) fungi, you might also want to look up the book Fungal Strategies of Wood Decay in Trees (I've put a photo of it below).

I'm far from an expert in fungi though so feel free to post a comment to correct me or to start a discussion!

In Part 2 we'll look at the effects on the timber of various white rots that make it valuable to woodcrafters. If you'd like to be notified as soon as that post is up, just subscribe to Ash + Axe's updates.

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