In England and Wales, a woodland is deemed ancient if it has existed with continuous tree cover since at least 1600 (1750 in Scotland). The distinction may seem arbitrary, but acknowledges the fact that older tree-ed landscapes tend to have greater ecological value.
To determine the age of a woodland, you can consult historic maps and records, or you can get out and look at its flora. Newer woodlands tend to be big on the pioneer species – those with windblown seeds, for instance, while ancient woodlands usually have a greater abundance of plants that spread slowly over the ground, such as wood anemone, wood sorrel and ransoms, and those whose seeds fall close to the parent, as do those of the wild service tree.
These plants, along with guelder rose, wood spurge and small leaved lime, are some of our most common ancient woodland indicators. As well as being slow-growers, they require long-term, stable woodland cover to survive and are easy to recognise.
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Main image: Wood anemones are perfect indicators that a forest is older. © Mandy Disher/Moment/Getty