Booderee contains representative examples of southeastern Australian coastal communities, which are threatened by urban development, rural activities, pollution and exploitative use elsewhere. The park is located in a transition zone between northern and southern biogeographical regions and its biota is diverse and scientifically interesting. The Botanic Gardens was established in Jervis Bay because of this overlap in vegetation types.
Identified communities in the park include terrestrial vegetation communities of eucalypt forest, relic rainforest, woodland, dry heath, wet heath, coastal scrub, wetlands and grassland; littoral communities of mangroves, saltmarsh, rainforest and intertidal rocky platforms; and marine communities such as seagrass beds.
The park has a relatively high average annual rainfall of 1,170 mm most of which falls in autumn and winter. The annual rainfall varies considerably over a long period. Consequently the ground water levels and depth of permanent waterbodies range from very low, after a series of dry years, to very high, after successive wet seasons. In some years, the water table extends to the surface in much of the low-lying western parts of the park.
The freshwater systems of the park range from ephemeral sheet and stream surface flows to permanent and semi-permanent streams, swamps and waterholes which may be self-contained or a surface expression of extensive ground water resources. All are integral components of the natural systems of the park and support varied and dependant plant and animal communities. There are several perched lakes. Lake Windemere and Lake McKenzie, both of which are closed freshwater dune lakes, are the largest permanent waterbodies in the park. Both are characterised by considerable cyclical water level fluctuations in response to climatic variations within a period of several years.
The relatively undisturbed condition, and the variety of plant and animal communities present, make the freshwater bodies of the park a valuable conservation and scientific reference resource. Alteration to catchment drainage patterns in swamp and wet heath areas can change the structure and composition of the vegetation.
The terrestrial vegetation communities of the park are of high conservation value as they include a range of vegetation types threatened on the New South Wales coast by urban development. To maintain the viability of communities it is essential that the area not become isolated in regard to management and that Bherwerre Peninsula continues to be linked with natural areas in New South Wales. In this regard it is vital that vegetation communities on the Peninsula be managed sensitively and cooperatively.
The majority of terrestrial communities in the park are adapted to periodic fire. In the absence of a natural fire regime, the planned use of fire as a management tool is required to maintain the diversity of vegetation communities.
The park provides the largest stronghold for the endangered Eastern Bristlebird Dasyornis brachypterus in Australia. This species has suffered alarming declines in range through predation by cats and foxes and loss or alteration of habitat. The park also provides habitat for the Ground Parrot Pezoporus wallicus. The Eastern Bristlebird and Ground Parrot have specific habitat requirements, especially with regard to vegetation. The endangered or rare status of these species will require special consideration in terms of research effort. Wetland habitats of the park are not extensive but are significant. Freshwater bodies such as Lake Windemere, Lake McKenzie and Ryans Swamp are vital for the breeding requirements of the Eastern Snake-necked Turtle Chelodina longicollis. The lakes also provide habitat for Black Swans Cygnus atratus, Swamp Harriers Circus approximans and many species of frogs.
The park encompasses approximately 840 ha of Jervis Bay waters, and area which comprises approximately seven per cent of Jervis Bay and 13 per cent of the total area of the park. The marine environment of Booderee is excellent representation of largely pristine marine environments of the southeastern temperate region of southeast Australia and is characterised by a wide range of tidal and subtidal habitats. These include shallow rock reefs and sand zones, seagrass meadows, deeper silty sand flats and deep water rocky reefs, cliffs, platforms, blocks, boulders and caves.
The high water clarity of the bay is due to the following factors:
- no major rivers flow into the Bay so very little sediment or other river-borne material is deposited;
- the entrance is flanked by rocky coast with no beaches of any size and the cliffs plunge straight into deep water for most of their length;
- no heavy industry is present in the Bay; and
- a moderate degree of urban development means there is limited sewerage discharge.
The intertidal rock platforms of Bowen Island are particularly significant as they harbour a great variety of intertidal organisms including large numbers and varieties of sea urchins, crabs, abalone, oysters and other organisms depleted elsewhere by human collection and foraging. There are few if any other areas where such a diversity of marine habitats and biota occur in such a small and easily accessible area, situated close to major population areas. Many species present in the marine environment are at the northern and southern limits of their ranges.
Bowen Island also supports a substantial colony of the little penguin, Eudyptula minor, and breeding colonies of three species of shearwater - making it of high conservation significance.
The clear waters of the Bay enable the growth of extensive seagrass beds and support a rich diversity of marine life. The seagrass beds contain three genera: Posidonia, Zostera and Halophila. The seagrass areas are of special interest as they rank fifth of the 133 estuaries in terms of total seagrass species found in NSW. Due to the clarity of the Bays waters and deeper penetration of light some plant species (such as seagrass Posidonia sp.) are located at greater depths than expected. These areas provide habitat for a diversity and abundance of fish and macro invertebrates. Subtidal and intertidal platforms support a diversity of rocky reef algae with Hormosira, Ecklonia, Sargassum, Phyllospora and Cystophora being the dominant genera.
The littoral communities of the park are of both local and statewide significance. They include mangrove communities along Sussex Inlet and south of Whiting Beach; saltmarsh communities at Flat Rock Creek and on the southern section of Bowen Island; and intertidal rocky platforms.
The mangrove communities provide habitat for a number of intertidal estuarine organisms, fish and terrestrial species. They also aid in sediment stability and enhance productivity in estuarine ecosystems. Saltmarsh communities are of high conservation value as bird feeding areas.
The rock platforms contain pools, which are regularly exposed at low tide. The intertidal rock platforms of Bowen Island harbour large numbers of sea urchins, crabs and other organisms depleted elsewhere by human collection and foraging.