The rainforest is a very dense, luxuriant, moisture loving class of forest and which usually contains a number of different tree species. Rainforests are unique in that they usually lack eucalypts. There are 5 main rainforest areas in NSW:
The valleys of the Richmond & Tweed Rivers and adjacent ranges
The Dorrigo Plateau
The catchment of the Hastings River
The slopes of the Barrington tops
The Illawarra-Robertson district of the south coast.
The greatest variety of species occurs on the northern fertile soils which are usually basalt or alluvial. Trees found here include ROSEWOOD, WHITE BEECH, SILVER ASH and FIGS. On lesser fertile soils and to the south rainforests tend to be dominated by COACHWOOD, associated with SASSAFRAS, PRICKLY ASH and CRABAPPLE.
Large areas of the rainforest has been converted to farming land where the soil has high intrinsic fertility such as on basalts and alluvium. However, many rainforests trees although luxurious looking, grow on infertile soils for example, COACHWOODS.
In any given locality eucalypts tend to grow in groups of species, an "association". Examples of common associations follow.
- WHITE MAHOGANY COUNTRY - GREY GUM ASSOCIATION
These are forest types dominated by combinations of the 3 species and with other eucalypts. They are widespread on the coastal areas of NSW. Commonly occurs in association with BLACKBUTT occupying the shallow and excessively drained soils on the ridge tips whereas Blackbutts are found on the more favourable sites on the slopes. Found on the south coast but are more extensively developed along the north coast where they form a significant part of the native trees around Raymond Terrace, Bulahdelah, Taree, and Kempsey. Good durable timbers for poles, piles, sleepers and other hewn timber uses.
TALLOWWOOD - SYDNEY BLUE GUM ASSOCIATION
These timbers are widespread on the escarpment zone of northern NSW being best between 450-900m altitude in sites with high rainfall and on soils of moderate to high fertility. They produce stands of highly productive and valuable timber.
BROWN BARREL - MESSMATE - GUM ASSOCIATION
These trees replace the tallowwood - Sydney blue gums in the escarpment zones of southern NSW and at higher altitudes in the north. Highly productive forest types on the moister areas of the tablelands.