In this themed programme Ellie Harrison, John Craven and Anita Rani explore Britain's woodlands. Ellie is high up in the canopy with the scientists collecting leaf buds to learn more about the effects of CO2 on woodland. She then helps release some hedgehogs, one of the nations' favourite and most-threatened woodland species, back into the wild. John finds out what it takes to manage your own woodland and discovers that the return of the old craft of coppicing is proving a boom to wildlife. He also joins the conservationists using novel methods to increase the dormice populations in Shropshire's woods. And Anita discovers how to build with baked wood - using a new technique that hardens and weatherproofs timbers making them much more durable and better for building with. Adam Henson has the third and final of the Countryfiles Farming Heroes nominees. The biggest threat to British trees is disease - and in many cases there's no cure. Tom Heap investigates the threats to our woodland and finds out what we can all do to defend our trees.