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Thousands of trees have been planted by volunteers near Roadford Lake in Devon, the largest reservoir in the South West.
They will help to improve both the water quality and the habitat for wildlife.
Much of the existing Roadford Forest was planted 20 years ago. Two thousand new trees, a mixture of native broadleaf varieties, were added in Spring this year.
It can stop sediment and nutrients being washed off the ground and into water courses and it helps infiltration so it's stopping flash flooding.
Volunteers were brought in from local businesses to help with the planting, a benefit for their own physical and mental wellbeing too.