Crimped Gill...again

A much drier walk round Old Sulehay Forest today, though the paths are now decidedly slippery. Highlight of the visit was finding two birch logs supporting a very large number of Crimped Gill Plicatura crispa, a rare species round Peterborough that I've only recorded from two sites.

Most of its early records were from Scotland or the north of England, but even then it wasn't common, until fairly recently. 78% of all the records of this species in the Fungal Records Database of Britain and Ireland are from the year 2000 onwards, with some records from southern counties.

What has caused this sudden increase in frequency? Often climate change is cited as responsible for changes in species distribution, but it seems counter-intuitive that it should enable a northern species to move south.