Over 22.8% of the High Weald is covered by ancient woodland; in the form of a complex and interlinked mosaic of treebelts, shaws and small or large woodland blocks.
The High Weald’s woodlands harbour rare species such as the dormouse, the pearl bordered fritillary and the black-headed cardinal beetle. Nightjars breed in the open space created when woodlands are actively worked. The ancient woodland ground flora is species-rich and includes coralroot bittercress, another speciality of the High Weald.
The Weald supports 1,400ha of unimproved grassland habitat - nearly 20% of the entire resource of lowland meadow in England. Most of these meadows are scattered across the country: nowhere else is there such a concentration compared with the Weald.
There are distinctive zones of open heath, remnants of the area’s medieval forests, which are internationally important for their wildlife. Ashdown Forest is the largest area of open access land in South East England, 60% of which is heath.
The High Weald’s coastline is made up of shingle ridges, saline lagoons, salt marsh, reedbed, pits and wet grassland with 3,720 different species of plants and animals. It also supports important wintering waterfowl populations, one of the largest breeding populations of lapwings in Sussex, and a nationally important population of reed warblers.
Deeply incised narrow valleys, known locally as gills, create a moist micro-climate which harbours plant populations not found elsewhere in eastern or central England and which are hundreds of miles from other British populations. Such plants include ivy-leaved bellflower and hay-scented buckler-fern.
The gill streams are fast flowing, are often within woodland and support specialised range of plants and animals; particularly invertebrates and fish - including brown trout, bullhead and the endangered sea trout.
The area has unusual sandrock exposures ranging from the warm soft, crumbly coastal cliffs to harder, grey, inland exposures. The cliffs are of outstanding significance geologically and are extremely important ecologically; supporting a number of Atlantic species of mosses, liverworts and lichens. The coast is one of the few areas in the High Weald where Jurassic rocks are visible on the surface.
The areas has numerous ponds, many man-made - a legacy of use of the area’s natural resources. The rare great-crested newt is found in many and they also have a rich assemblage of uncommon water beetles and medicinal leech; uncommon plants such as frogbit, lesser water-plantain and tubular water-dropwort.