Wairambar the Ancient Refugia Area 

of the Oldest Continuous Rainforest on Earth 

Lat 17.4193S Long 145.7287E Datum WGS84

24Ha of rainforest bordering World Heritage Wet Tropics Rainforest in extreme terrain at an elevation of 700m in Far North Queensland Australia

The Wairambar Rainforest is an ancient refugia  with very high biodiversity. At 130 million years it is the oldest continuous rainforest on earth. It is located behind Chorechillum (Mount Bartle Frere 1620m) in far north Queensland, Australia.  Living things persist here despite climatic changes over the rest of the  Australian continent due to a unique location that provides reliable rainfall and a range of microclimates and soils. 

• If there is a low pressure system to the north or a high pressure system to the south then warm moist air blows up the mountain and creates clouds and / or rain.  

• The area has a  variety of soils... alluvial, granitic, basaltic and marine sediment derived metamorphic sediments.   

• A diverse topography  results in a range of local microclimates

These rainforests are of particular interest for the high degree of endemism of their primitive Gondwanan flora which records eight major stages in the earth’s evolution during 35 million years of isolation (many with ancient lineages) and animal species. High concentrations of endemic monotypic genera and primitive plant families reflect the refugium status of many parts of the ecoregion. They have numerous rare, threatened and endangered species and the only recognised Aboriginal rainforest culture in Australia.

The rainforests of northern Queensland straddle three major regions: the tablelands of the Great Divide,the Great Escarpment to their east, and the coastal plain. The tablelands are the undulating remnants of a warped elevated landscape scarred by vulcanism and characterised by scoria cones, lava cones and irregularly distributed maars the youngest of which are filled by Lakes Eacham and Barrine. They average 600-900m but rise to over 1,600m in Mt. Bartle Frere, the highest mountain in northern Australia.

The Great Escarpment retreated to its present position as the result of catastrophic erosion. It marks the limit of headward erosion of the tablelands above the coastal plain and is breached only by basalt flows, as in the Johnstone River system. It forms a belt of rugged topography, with rapid and ongoing geomorphological processes, varied environments, deeply incised gorges and numerous waterfalls. The plain is characterised by several steps where coastal submergence and retreats have led to river capture and the reversal of stream flow to the east.

The geological history begins with the formation in Palaeozoic times of a continental basement followed by  initiation of northwest trending drainage in the Mesozoic; and intensified doming to the east about 50 million years ago when Australia began to separate from Antarctica and move north. 

By the late Tertiary the new continental margin had foundered, causing the coast to retreat to its present position. During the whole period since the time when the angiosperms evolved, the ancient continental landscape remained tectonically stable. 

Most of the underlying slates, greywacke and greenschist facies are marine Silurian, Devonian and Carboniferous sediments of the Hodgkinson basin and Broken River embayment, the largely schist and gneiss Barnard metamorphics outcropping in the south-east of the basin. The greatest concentrations of volcanics and granite occur at the southern end of the basin where it meets the embayment. 

The tablelands and some coastal areas were greatly disturbed by basalt flows throughout the Pliocene and Pleistocene.

The Wairambar Rainforest sits on a diverse range of geology --> basalts, metamorphic marine sediments, quartzite, dolerite, possible leucocratic intrusives and quartz rich ridges all within deeply disected terrain with a wide range of micro-climates. Consequently is supports a rich diversity of ecotones

The soils derive from a wide range of parent rocks, alluvia and rainfall gradients. The parent materials consist of acid igneous rocks, low-grade metamorphics, basalt, and alluvium derived from these. The alluvium of larger streams is of mixed origin; that of smaller streams may be from a single source. The oldest metamorphic rocks break down to moderately deep medium-textured red or yellow loams; granite rocks and acid volcanics to deeper red podzolic soils and xanthozems; and basalts to deep to very deep krasnozems. The high nutrient level of the basalt soils may have helped the rainforest to resist stress during the fluctuating climatic conditions of the Pleistocene glaciations. Moisture is the predominant influence on the coastal plains. As the drainage becomes poorer the soils change from gleyed podzols to humic gleys and acid peats. As usual with heavily leached soils of the wet tropics, most have extremely low contents of exchangeable calcium, magnesium and potassium, usually relatively high amounts of extractable aluminium and are poor in humus. Erosion  occurs even under undisturbed rainforest . The major ecosystems types are 7.8.2 and 7.11.12 (Tracey & Webb)

The wetter parts of north-east Queensland are classed as wet to extreme wet on a global scale, with very high rainfall concentrated over the four-months of summer with a relatively dry winter. Widespread overland run-off, even on steep slopes, results from the intense rainfall onto saturated soils which is a common phenomenon not usual in other wet tropical rainforests. The mean annual rainfall ranges from 4,000mm near the coast to 1,200mm in the west, 75-90% falling between December and March. It is much higher on the mountain ranges, with an average of 8,529mm recorded on the summit of Mt Bellenden Ker. This property, the tablelands and uplands are cooler than the coast: mean daily temperatures range from a maximum of 28°C to a minimum of 17°C in summer and from 22°C to 9°C in winter. 

The Wairambar Rainforest averages around 4000mm of rain per year with high variability from year to year. Much of the rain is at night.

Directors: 

• Fryderyka Michna - Biodiversity, Research and Invasive Species

• Roberta Michna  - Rainforest Restoration and Rehabilitation

• Paul Michna - Species Identification and Logisitcs

• Joseph Michna - Social Media and Drone Imagery