Site Details

Area: 72.81 hectares

Designation

SSSI (Site of Special Scientific Interest)
SPA (Special Protection Area)
SAC (Special Area of Conservation)
Ramsar Site
SNCI (Site of Nature Conservation Interest

Owners: Local Planning Authority: Borough of Poole, Dorset County Council
Managers: Local Planning Authority: Borough of Poole, Dorset County Council

Site Description/Habitats

This site, along with Talbot Heath, comprises two fragments of semi-natural heathland lying within the valley of the Bourne Stream, which form part of a linear strip of remnant heathland within the conurbation of Poole. Bourne Bottom is a site of remarkable habitat variety, comprising large compartments of dry heath on higher elevations, with significant areas of humid and wet heath and valley mire. There are also areas of willow/alder carr, secondary oak/birch woodland, open amenity grassland and a few area of open water surrounded by fringing aquatic vegetation. Bourne Valley SSSI is part of a complex of heathland sites which together comprise the Dorset Heathlands. This is one of the major lowland heathland areas in Britain, with the sites showing a degree of ecological cohesion and clear ecological trends and patterns. The heathlands are important in a European and international context for their plant and animal communities. The Bourne Valley site covers the largest tract of heathland that has survived within the spread of the Bournemouth-Poole conurbation on the formerly extensive heaths that once bordered Poole Bay. Sequences of heath, mire and fen woodland vegetation types are well developed and typical of lowland valley heathland in southern Britain. These habitats, the Bourne stream and several ponds support a range of rare and uncommon plants, birds, reptiles and invertebrates. The assemblage of dragonfly and damselfly species is especially rich.

The heathland is centred on a deep and narrowly enclosed section of the Bourne Valley, extending along a 3km length from near the valley head on the border of Canford Heath. Several other heathland fragments lie in an adjoining, parallel valley on the south side which is more extensively developed. Such fragmentation has occurred throughout the Dorset heaths, with about 86% having been lost since the mid 18th century. The Bourne Valley contains the only substantially intact valley heathland that remains along the many deeply incised valleys and chines leading to Poole Bay. The valley ridges lie on river terrace deposits of gravels and sands, probably laid down by an ancient Solent river system during the Quaternary era. In the valley these deposits have been removed with the downward cutting of a formerly more substantial Bourne stream, creating steep slopes on the underlying sands and clayey sands of the Branksome Sand. This geological history has provided poor and mostly well drained soils which have favoured the development of dry heath.