Martin Walters inspects some of the amazing species.
They want people from every continent to join in.
Youngsters aged 7-18 can win great prizes by entering before February 24.
Debbie Baxter, a Cambridge artist who has previously been featured on the BBC's Countryfile, discusses the power of trees.
Plus a livestream view - and tips on photography a spectacle that hasn’t been seen for 800 years.