https://ancienttreeforum.co.uk/wp-content/uploads/2015/02/ATF_book.pdf#page=99 page 98 If a stub is to be retained, either for the reasons stated above, or when a tree is to be reduced to a "monolith" …, unconventional methods of cutting or fracturing (not recommended in BS 3998) may be employed, … https://ancienttreeforum.co.uk/wp-content/uploads/2015/02/ATF_book.pdf#page=148 page 147 Even dead standing or fallen trees are important, and so owners should be encouraged to be untidy-minded and to leave monoliths or fallen dead wood in situ.