King Alfred's Cakes
Daldinia concentrica
The King Alfred's Cake is a saprotrophic ascomycete fungus in the family Xylariaceae. It produces hard, coal-like fruiting bodies that reveal characteristic concentric rings when sliced open. It is a significant wood decomposer, primarily found on dead ash logs and branches.
Details
Identification
Hemispherical, black fruiting bodies; internal concentric layers visible in cross-section; hard, brittle texture; primarily found on ash wood.
Diet
Saprotrophic; decomposes lignin and cellulose, thereby causing white rot in the wood.
Spawning substrate
Dead hardwood, particularly ash (Fraxinus excelsior), less commonly birch or alder.
Overwintering
The fruiting bodies are persistent and can remain on the substrate throughout the winter.
Ecology
Ecological role
Important primary decomposer of deadwood; contributes significantly to the nutrient cycle in forests.
Natural predators
Specialized mycetophagous insects such as the beetle Platyrhinus resinosus.
Competitor species
Other wood-decaying fungi of deciduous forests such as Hypoxylon species or bracket fungi.
Ecosystem service
Nutrient recycling and provision of habitat for micro-organisms.
Threats
Removal of deadwood in forestry; decline of ash trees due to ash dieback.
Scientific profile
Profile
Distinguishing features
The most important feature is the concentric rings in the cross-section of the stroma. Unlike Daldinia childiae, D. concentrica primarily prefers Ash (Fraxinus) as a substrate. Microscopically, the ascospores (12–17 x 6–9 µm) and the reaction of the ascus apical ring in Lugol's solution are diagnostic.
Habitat
Deciduous mixed forests, alluvial forests, parks, and gardens, preferring sites with a high proportion of ash trees and sufficient deadwood availability.
Reproduction
Sexual reproduction via ascospores produced in perithecia beneath the stromal crust. Spores are actively ejected during periods of high humidity (mostly at night).
Protection & threats
Main threats
Threatened by the decline of the European Ash due to ash dieback (Hymenoscyphus fraxineus) and intensive forestry (removal of deadwood).
Conservation measures
Promotion of deadwood levels in forests, protection of ash stands, and leaving infested trunks within the ecosystem.