First and foremost, I wish to extend a thank you to David Humphries for confirming that what I was looking at here was Pseudoinonotus dryadeus. Given the condition of the (significantly lacking) brackets, I had only anticipated them being P. dryadeus because of the algal greening atop their structure, though having not seen this fungus in abundance it was very much an ‘educated’ guess.
The below pictures taken of the desiccated brackets around the butt of an oak (which sits on a woodland edge next to a golf course) are very telling. Classic bottle butt associated with a white rot (in this case, it is a selective white rot) can be seen, and consulting the very brilliant Arborist’s Field Guide by Guy Watson and Ted Green, the buttressing present here is indeed indicative of P. dryadeus decay. The authors state: “many trees stand on ‘stilts’ of buttress roots where the fungus has decayed the central wood completely, giving the appearance of the Eiffel Tower.”
Of course, failure is a risk. If decay extends into the buttress zones, or the buttresses have been weakened via other means, then windthrow may be of a higher possibility. Given this oak is a woodland edge tree, and the target zone beneath is frequently used (particularly in summer), management of the hazard via means of pruning may very well be something to consider.