Although the Epping Forest Act almost certainly saved the forest from total destruction, it has to some extent had a deleterious effect on the area's biodiversity. The pollarded trees allowed light through to the woodland floor, increasing the numbers of low-growing plants. Since the Act, the vast crowns of the pollards cut out most of the light to the underbrush. In addition, the area surrounding the forest is now to a great extent urbanised; the corresponding reduction in grazing has led to some former areas of grassland and heathland being overcome by secondary woodland. In recent years, the Conservators have experimented with pollarding in selected areas of the forest, and a herd of English Longhorn cattle has been reintroduced to graze the heathland and grassland.