Complex sentence: It is a tall, rangy animal, adapted to foraging in woodland, its original habitat in the New Forest, where there is a long tradition of allowing pigs to forage in woods for mast (acorns, beech nuts and chestnuts).
Split into simpler sentences: It is a tall, rangy animal, adapted to foraging in woodland, its traditional use. This use survived longest in the New Forest, where pigs are still allowed to forage in woods for mast (acorns, beech-nuts and chestnuts).