As Countryfile's Plant Britain initiative to plant three quarters of a million trees across the UK reaches its climax, John Craven and Ellie Harrison are at the Countryfile wood in Cheshire. Planting here began just two years ago, but John and Ellie discover how the saplings are already helping nature. Ellie also checks out the positive impact trees have on the planet, from seed to deadwood. Charlotte Smith finds out how community gardens are changing lives and discovers the fascinating underground system that enables trees to talk to each other. Tom Heap visits the high-security government labs working to protect trees from climate change and disease. And finally, after two years of Countryfile viewers so magnificently pulling together, John and Ellie reveal an exciting update.