Aspen

Excavates nest holes in Aspen more readily than in oak. The soft, fast-decaying wood requires significantly less effort. Aspen stands are disproportionately important for woodpecker nesting density relative to tree abundance.

Excavates nest cavities in soft aspen heartwood, especially where fungal heart-rot is present; Aspen's rapid decay makes it a preferred nesting substrate in mixed woodland.

Obligate secondary cavity nester, strongly associated with aspen woodpecker holes.

Uses Black Woodpecker and Great Spotted Woodpecker cavities in large aspens.

Nests in dead or dying Aspen, particularly where Tinder Fungus has softened heartwood.

A primary heart-rot pathogen of living Aspen, creating decay columns that are subsequently excavated by woodpeckers as nest cavities. A documented fungus → bird facilitation chain.

Obligate host-specific white-rot parasite of Aspen; causes the heartwood decay essential for cavity-nesting birds.

Saprotrophic and weakly parasitic on Aspen in boreal and montane woodland.

Also commonly found on Aspen stumps and standing deadwood.

Near-obligate ectomycorrhizal partner; Aspen is the primary host throughout the European range.

Also forms ectomycorrhiza with Aspen in riparian and lowland woodland.