Australia: The Land Where Time Began

A biography of the Australian continent 

Subtropical Rainforests - Northeast New South Wales and Southeast Queensland       Species found in the Subtropical rainforest

Summery

Subtropical Rainforest is usually found where rainfall is above 1300 mm per year, on fertile parent rocks, basalt and rich shales, commonly in sheltered gullies from sea level to about 900 m. Usually 10-60 tree species with a well-developed multilayered canopy. Many of the trees have buttresses, as commonly found with rainforest trees. Strangler species, especially the ubiquitous Strangler Fig, Bangalow Palms, woody vines, orchids and other large epiphytes, elkhorns, staghorns and birdsnest ferns, with ground ferns and large-leafed herbs. Some of the more common trees usually found in this type of rainforest are Booyong (Argyrodendron spp.), Yellow Carrabeen (Sloanea woollsii), Rosewood (Dysoxylum fraseranum), the Fig (Ficus spp) and Lilly Pillie (Syzygium) families. Some of the main areas where this rainforest type occures are Tamborine Mountains National Park, Lamington Nation Park, Border Ranges NP, in the more sheltered parts of the Mt Warning NP, Minyon Falls in the Whian Whian State Conservation Area and Nightcap NP. An example of this rainforest can be seen at Stott's Island in the Tweed River, between Tweed Heads and Murwillumbah.

This rainforest type has a dense multilayered tree canopy, 20-40 m tall, contains large emergent trees such as figs and cedar, with a sub-canopy of smaller trees including palms. The canopy is usually composed of many species with a wide range of leaf size up to 30 cm long, and many compound types composed of 2 or more leaflets. The trees often have buttressed trunks, their branches covered with a variety of epiphytes, orchids and ferns, or with lianas draped over them, up to the highest branches. Scattered saplings and shrubs comprise the open understorey, and a large amount of litter and a patchy cover of herbs and ferns.

Subtropical Rainforest have the most diverse tree flora of any Australian vegetation type outside the Tropical Rainforest of northeast Queensland. The canopy composition varies greatly, both between local stands and between regions, depending on factors such as soil type and microclimate, the species diversity declining from north to south. Subtropical Rainforest is scattered from the Gold Coast hinterland in Queensland to the Shoalhaven River in New South Wales on the coastal lowlands and escarpments, including the Lamington Plateau in Lamington National Park. Some outliers are further south as far as Milton and Little Dromedary, though these patches have obvious affinities with Dry Rainforest. There are large stands in the Mt Warning Caldera, near Lismore in some remnants of 'the Big Scrub', the Bellinger and Hastings valleys, and the foothills of Barrington Tops. In southern New South Wales there are stands in the Illawarra and Kiama districts. In Queensland they are found on the Lamington Plateau, including the Lamington National Park.

Wherever they are situated, this type of rainforest requires annual rainfall of more than 1300 mm. They grow on rich soils that are derived from basic igneous rocks, or in coastal lowlands, on alluvium, in valleys and riparian corridors, and in the coastal ranges, in gullies and foothills. Occasionally it can be found extending up gullies in the escarpment to altitudes of as much as 900 m, though in this environment the species diversity is usually lower, often being dominated by Sloanea. In the habitat where they usually grow typical conditions such as fertile soil, warm temperature, a reliable water supply, are the conditions that also lead to rapid, luxuriant growth that supports high diversity of mammals and birds, and especially great diversity of insects in the canopy and the litter layer. They are a significant refuge for relict species from the Gondwanan rainforests.

Large stands still survive in some inaccessible areas such as the Border Ranges, Nightcap Ranges, New England Escarpment and Dorrigo Escarpment, west of Kempsi, Mt Seaview, and near Jamberoo, Minnamurra Falls.

Sources & Further reading

 

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Last updated  25/02/2010

 

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                                                                                           Author: M.H.Monroe  Email: admin@austhrutime.com     Sources & Further reading