More or less constant rain: bad light.
Everything shown today is from just one specimen of Hawthorn in the middle of mixed forestry. I suspect the Hawthorn actually pre-dates the coniferous plantation. It overhangs a deep gulley with fast-flowing water in it. This damp environment leads to a host of lichens and fungi, as this set of images shows. Species identified so far include Cladonias and Xanthoria parietina in addition to those shown below.
Mycena galericulata often grows through mosses on wood. The stipe is very robust and springy.
A shot of the gills on the tumbled specimens.
A Hypogymnia tubulosa lichen with an overgrowth of Trentepohlia alga (orange spots).
Thelotrema lepadinum (love the metre on that name) is a crustose lichen that appears to propagate by spores (the crater-like fruit bodies) and thallus division (the crack to the right and the almost rectangular missing portion to the top left.
This moss drips from most of the branches. Hypnum andoi.
An excellent tree.