Countryfile - 23/11/2008

John Craven heads to Wytham Woods in Oxfordshire which is being used as a giant open air laboratory to study the effects of climate change. Michaela Strachan lends a helping hand to the team at Westonbirt Arboretum, challenged with building a wooden barn in just one day and Adam Henson dons his walking boots to explore a new version of Alfred Wainwright's Pennine Walk.