Headon Warren is an example of a lowland acid heath and West High Down and Tennyson Down are chalk ridges with a rich calcareous grassland community; the close proximity of these two different plant communities in a maritime setting is of scientific interest. The vegetation on the warren is dominated by heather, bell heather, gorse and dwarf gorse. There is a ground cover of heathland plants, and the Dartford warbler breeds here. There are also areas of scrubland, and the cliffs of The Needles, The Needles Batteries and Alum Bay are included in the site.