Variations in flora across the Kimberley reflect extremes in distribution of rainfall and a variety of soil types. The north Kimberley features dense eucalypt woodlands, mangrove forests and remnant rainforest pockets. In the central Kimberley the dominant features are savanna woodlands, with sparse acacia scrub land and spinifex savanna in the south.
Remnant Rainforest Pockets
Approximately 1,500 remnant rainforest pockets occur along the coast in areas of heavy rainfall and in protected locations, containing about 25% of the Kimberley’s 2,000 species of plants. Although found primarily in the north west Kimberley, the rainforest pockets also extend down the Dampier Peninsular as far south as Broome and are the only rainforests in Western Australia; in fact their existence was not recognised until 1965.
The average rainforest pocket is 3ha. These rainforest pockets support a wide range of species of flora and associated fauna such as the Scaly-tailed possum that do not occur elsewhere in Western Australia. Many small invertebrate species are unique to Kimberley rainforest pockets.
The Kimberley coast is also notable for its extensive mangrove communities, which form low closed forests on tidal flats. Seventeen of Western Australia’s twenty-seven species of mangroves are found in the Kimberley. These mangrove communities are more species rich than those further south, and are an important biological feature supporting diverse land and marine faunas including many species dependent upon this habitat.
Boabs (Adansonia gregorii) grow along the Kimberley coast, displaying a great tolerance to salt, and often found almost down to the water’s edge. In coastal areas with strong winds, the Boabs may be somewhat stunted in growth.
Pandanus spiralis, or Screw palm, grows along the Kimberley coast along watercourses, on the coastal fringes and dune systems. Growing up to 10m in height, the plant is characterised by the spiralling nature of the trunks. The plants produce a distinctive red pineapple like fruit, which was utilized by Aboriginal people as food.
The predominance of grasses from a wide range of genera is another important feature of the Kimberley flora. Beach spinifex (Spinifex longifolius) is a common sight on the foredunes of Kimberley beaches, along with native sedges.
Stinking passionfruit (Passiflora foetida), an introduced species from South America, has gained an extensive hold over the Kimberley’s islands and mainland. The green fruit are toxic.