About 15 years ago livestock grazing ceased in this field, on the southern edge of Blaid’s Wood, two miles south of the city center. An aerial invasion from wind-borne tree seeds followed, and ash, silver birch, alder, and willow seedlings appeared everywhere. The bird-sown seed of bramble, briars, and hawthorn sprouted. A few oaks even arrived, from acorns cached by jays then forgotten.