Forty million years ago, Australia was largely covered in rainforest. As it drifted north, having separated from the southern super-continent Gondwana, the climate became drier and the rainforest contracted to the wet tropics, the eastern subtropics and temperate areas in the south of the continent and Tasmania. By 1750 the distribution of Subtropical Rainforest had contracted to 200,000 ha in north-east NSW and south-east Queensland. The largest contiguous area of this rainforest was the Big Scrub, which covered 75,000 ha on the southern flank of the Mt Warning caldera from the foothills of the Nightcap Range in the north to Byron Bay, Ballina, and Lismore in the south.
For thousands of years before European settlement, local Aborigines lived in and used the Big Scrub and coastal rainforest. The forest provided an abundance of food, including Macadamia nuts, figs, wild grapes, yams, Cunjevoi roots, the hearts of Bangalow and Cabbage Tree Palms, Black Bean seeds, brush turkeys, bandicoots, pademelons and small wallabies. The Big Scrub was also a place of spiritual significance with remains still visible today.
In the 30 years following European settlement, 99% of the Big Scrub was cleared, primarily for agriculture. All that remained were 80 mainly small patches of remnant rainforest with a total area of less than 750 ha. The rest of the Lowland Subtropical Rainforest in NSW and Qld suffered a similar fate, with 90% being cleared.
The remaining remnants of the Big Scrub have lost their ecological context and are now isolated islands of vegetation in an ocean of cleared lands. They are trapped in time with many species, particularly in the smaller remnants, lacking the population size and genetic diversity to be self-sustaining in the long term.
Lowland Sub-tropical rainforest has between 30-60 canopy species occurs below 300 m elevation on basalt-derived deep red earths and floodplain alluvium.
Characteristics include:
moist forest type with high rainfall (more than 1300 mm)
buttresses common
moderate to high species diversity: 10-60 species in the canopy
two or three strata of trees
strangler figs and palms common
large vines common
epiphytes common and diverse
intermediate to large leaf sizes (notophyll)
Common species include White Booyong (Argyrodendron trifoliolatum), Native Tamarind (Diploglottis australis), Pepperberry (Cryptocarya obovata), Black Bean (Castanospermum australe), Cudgerie (Flindersia schottiana), Hairy Walnut (Endiandra pubens), White Bolly Gum (Neolitsea australiensis), Red Bean (Dysoxylum mollissimum), Yellow Carabeen (Karrabina benthamiana), and Starngler Fig (Ficus watkinsiana).
Rainforest restoration aims at improving ecological function by restoring structure, species diversity and habitat values. This ensures the long-term viability of rainforest at a local and landscape scale, genetic diversity and sustainability of flora and fauna populations. Three components incorporated in my attempts at restoration on my 5 acre property include:
Rehabilitation - the care of rainforest remnants
Re-establishment - planting rainforest trees on cleared land
Camphor Laurel conversion - transforming a Camphor Laurel forest to rainforest.
References
Australian Rainforest Plants I-VI, 2nd ed. 2003. Nan & Hugh Nicholson. Terania Rainforest Publishing.
Plants of Subtropical Eastern Australia. 2020. Andrew Benwell. CSIRO Publishing.
Subtropical Rainforest Restoration, 3rd ed. 2019. Published by Big Scrub Landcare.
The Big Scrub Rainforest. A Journey Through Time. 2017. Ed by Shannon Baunach-Greenfields. Published by Rous County Council and Big Scrub Landcare.
