The Oasis Valley has been designed to inform visitors of Australia’s biogeographical history and raise awareness of the importance of Australia’s dry rainforests.
The term “dry rainforest” may sound like a misnomer but not all of Australia’s rainforests grow in areas receiving evenly distributed, abundant supplies of rainfall. There are four major types of rainforest in Australia and several sub groups.
The majority of native plant species making up the different types of Australian rainforest evolved from the ancient subtropical Gondwana rainforests which covered most of Australia 40-50 million years ago. The plant families in these ancient forests included Nothofagaceae, Araucariaceae, Podocarpaceae and Proteaceae.
As the climate became less suitable for rainforests, those species best suited to the arid conditions and changing environment survived and evolved creating the native species we are familiar with today.
Dry rainforests grow in regions with distinct wet and dry seasons. They are classed as rainforest mainly because of the closed canopy as well as genera composition that is largely similar to that of 'normal' rainforest.
Dry rainforests have been reduced to tiny remnants scattered across the Kimberley, Top End, Cape York, North Hunter Valley and down the east coast of Australia.
The Oasis Valley contains over 40 different dry rainforest species representing 16 families and 27 genera. The plantings have been grouped together according to their families to make it easier for students of biology and botany to compare their characteristics.
Near the beginning of the boardwalk, on the right hand side, visitors may observe the variation in the Brachychiton genus. Although closely related, Brachychiton acerifolius (Flame Tree), Brachychiton discolour (Queensland Lace bark), and the Brachychiton rupestris (Queensland Bottle Tree) differ greatly in foliage, habit, and bark. Each has evolved to survive under particular environmental conditions.
The relatively new Oasis Valley brings an exciting dimension to the Dubbo Regional Botanic Garden and as the trees grow, eventually dominating the boardwalk, visitors will enjoy a unique rainforest experience.
By Ian McAlister & Karen Hagan