Kevin Mills, Member of National Parks Association of NSW
“The reserve is a botanist’s paradise with scores of trees with birds’ nest ferns, elks’ horns, ferns and orchids.”
H. A. Grace, visitor to Minnamurra Falls in 1896.
The botanist certainly finds much of interest at Minnamurra and the most casual visitor cannot help but be enthralled by the diversity of plants, in form and in species, and the scenery of this enclosed valley. Huge fig trees tower well above the general rainforest canopy, large vines entangle the tree tops and hang off their trunks in great loops, while large bird’s nest ferns adorn many of the trees. Crossing the river several times by suspension bridges supported by thick cables, the boardwalk snakes its way up the narrow valley through one of the best examples of subtropical rainforest towards its most southern limit of occurrence in eastern Australia.
The Minnamurra Falls were discovered early in the 1800s, probably as timber getters pushed into the escarpment forests looking for their quarry, Red Cedar Toona ciliata. The area around the falls has been a public reserve for many years; initially an area of 47 acres (19 hectares) around the falls was declared in 1904, although it had been discussed since about 1896. The area was managed by the local council for many years and finally added to Budderoo National Park in 1986, nearly 100 years after its dedication as a public reserve was first mooted.
The upper Minnamurra River catchment straddles the Illawarra Escarpment about 13 kilometres west of the mouth of the river, located to the north of Kiama. Most of the steep, upper catchment on the face of the escarpment is within Budderoo National Park. From an altitude of 770 metres on the summit of Knights Hill above the escarpment in the west, the Minnamurra River falls 700 metres to only 70 metres above sea level at the eastern edge of the National Park, over a river distance of about 5.3 kilometres, 81 percent of which is within the national park. The upper gorge begins about 300 metres west of the escarpment cliffs and drops for most of its height, over 400 metres, in the next one kilometre. Over that length, the river drops in a series of waterfalls, the highest being Minnamurra Falls, before gently falling for the next 1.5 kilometres to the eastern boundary of the National Park.
The geology is complicated and is reflected in the complex pattern of plant community types. The lower to mid escarpment slopes are volcanics of Permian age, over which are the sediments of the Sydney Basin, most notably the Hawkesbury Sandstone that forms the cliffs above the steep slopes of the escarpment face. Above the sandstone lies the sedimentary Wianamatta Group and atop Knights Hill the Tertiary Robertson Basalt. Two local igneous sills intrude into the Illawarra Coal Measures in the upper gorge, namely the Minnamurra Latite Member and Wallaya Dolerite.
The diversity in the geological substrate and the significant variation in altitude are responsible for the occurrence of several different rainforest types and other vegetation in the valley, including tall moist eucalypt forest. A catena of rainforest communities can be recognised, from the lowest eastern point to the high altitude basalt soils on the plateau to the west. Dry lowland rainforest gives way to subtropical and warm temperate up the valley. While at high altitude the rainforest exhibits cool temperate affinities. The valley contains one of the finest and most important stands of subtropical rainforest south of the Hunter Valley.
An abundance of ferns
One significant feature of the Minnamurra Rainforest is the abundance of ferns. The upper Minnamurra River valley contains 96 fern species, representing 55 percent of the state’s fern flora and 82 percent of the South Coast region’s ferns. This is an especially high percentage for such a relatively small area and is unlikely to be repeated anywhere else in southern New South Wales.
Several threatened and rare ferns and other species can be found in the upper Minnamurra River valley; these range from locally endemic trees to rare orchids. An important feature of the rainforest is the high number of species that are rare in southern New South Wales, some of which either have their most southern limit of distribution at Minnamurra or not far away. The concentration of so many significant plant species, along with the diverse natural subtropical rainforest so far south of its common occurrence, makes the Minnamurra valley of national importance for botanical conservation.
Encounters with wildlife should be anticipated, including lyrebirds scratching amongst the forest litter beside the walking tracks, ignoring passing visitors. In the warmer months, Easter Water Dragons are common along the creek, while fruiting palms and figs attract flocks of Topknot Pigeons.
Education and tourism
The Minnamurra Falls area, now known as the Minnamurra Rainforest Centre, has been a well-visited tourist site for over 100 years. Generations of school children have visited Minnamurra and continue to do so as part of their education. The rainforest ecosystem has survived timber getting, wildfire, small scale settlement and attempted coal mining. The remnants of this human endeavour are scattered throughout the forests, including piles of rock (piled up to clear grazing land), debarking of huge old Turpentine trees (obtaining bark for hut construction), old fences and the remains of abandoned tourist facilities. Today, the area is managed by the NSW National Parks and Wildlife Service for conservation in conjunction with passive recreation and education. The area is also a major location for botanical and other rainforest research.
Minnamurra Rainforest is an icon for rainforest conservation in the south of the state, and its scientific importance and scenic attractiveness should be recognised and celebrated. The visitor centre contains displays, a shop and there is a cafe. Access is off Jamberoo Mountain Road west of Jamberoo. The site is open from 9.00 a.m. to 5.00 p.m. every day of the year except Christmas Day, unless closed due to flooding or bushfire.
Note. Work may be being undertaken on upgrading the walkways, so it is best to check Minnamurra Rainforest Centre online for current track information.
Kevin Mills is an ecologist based on the south coast and a long time member of NPA.