The Daintree - the oldest rainforest in the world
In the north east of Queensland, Australia, there is a coastal region called the Wet Tropics. The Wet Tropics has been included on the World Heritage List for representing major events in evolutionary history, having examples of on-going evolutionary processes and developing ecosystems, it’s natural beauty, it’s cultural importance and it’s importance for conservation and the protection of threatened species.1
Within this region is the largest area of rainforest in Australia. Comparatively to the size of the Australian continent, it is a small area of rainforest. It is small in comparison with rainforests in other parts of the world as well, such as the Amazon. This little rainforest, however, is special for another reason, among the others already mentioned: it is said to be the oldest continuous rainforest in the world.2 The Daintree rainforest, named after Richard Daintree, an English geologist and photographer, covers a lot of this area.
”Where the rainforest meets the reef“
The Daintree rainforest, river and national park are part of the Wet Tropics World Heritage area. The rainforest runs along the coast of Northern Queensland, meeting with another precious World Heritage listed area: the Great Barrier Reef.
The oldest continuous rainforest in the world
The Daintree has features respresenting significant events in evolutionary history and is a major biome of genetic diversity.1
A rainforest, by definition, is a forest that receives a high amount of rainfall or moisture. A tropical rainforest is one that falls roughly within the tropical latitudes of the planet - around the equator and between the Tropic of Capricorn and the Tropic of Cancer. A temperate rainforest on the other hand resides roughly within the temperature regions of the globe - within the higher “middle” latitudes either side of the tropics.
Much of the landmass that the Daintree rainforest now covers is said to have been formed in the Palaeozoic era (hundreds of millions of years ago).1 When Australia was thought to be part of Gondwana, rainforests were thought to be covering the majority of the continent.2,3 It is proposed that the Daintree and surrounding rainforest is remnant from this Gondwanan rainforest, making it the oldest continually surviving rainforest in the world.
180 - 135 million years old is the range quoted by some tourism companies as being the age of the rainforest. This correlates to when most scientists believe a tropical climate extended into the ”middle” lattitudes, the polar regions had a temperate climate4 and before Australia separated from Gondwana (also part of Pangea at this time).5
There are many cycads, known as “living fossils”, growing in the Daintree today. The earliest cycads were found in fossils roughly 300 million years old, while the oldest in Australia are from roughly 245 million years old.6 Many of the plant fossils found in Australia from the Eocene epoch (56 - 33.9 million years ago) grew in forests with the same types of plants that are in the Daintree today.2,6
In more “recent” times, during the Pleistocene epoch (~2.5 million years ago - 11.7 thousand years ago), the rainforest apparently survived dramatic climatic variations and glacial cycles. During these climate fluctuations the rainforest periodically and dramatically contracted becoming a sanctuary for species during the glacial periods.3,7,8,9
One species that is an icon of the Daintree rainforest is the cassowary, Casuarius casuarius, L. This incredible flightless bird - a dinosaur, if you wish - is a frugivore that eats the raw rainforest fruits and, in doing so, assists with the dispersal of tree seeds throughout the rainforest. It is regarded as a ”keystone“ species and an engineer of the rainforest. Some seeds even have an improved probability of germination after being consumed by a cassowary. One seed has been shown to have no germination without passing through the bird.10
It is suggested that as early as 45,000 years ago there were humans in the Wet Tropics (Atherton Tablelands).11 This idea comes from evidence we have of biomass burning. There is no archeological evidence from this time though (possibly due to inaccessibility and the difficulty of finding artifacts in the dense vegetation). The earliest archeological evidence of humans in the rainforest is ~8,000 years old from a location called Urumbal Pocket near the Tully River.12 Oral stories passed down by the aboriginal people may hint at humans being in the area before this time. The stories describe events such as the creation of local volcano craters formed 13,000 years ago and sea level rising in the early Holocene. From around 2,000 years ago more permanant occupation by aboriginals becomes evident.12
Since land has been cleared for industry such as farming, the rainforest has shrunk further than it had due to climatic changes.7 Fortunately, there is now a greater awareness of the importance of the rainforests and the wet tropical rainforests of Australia are largely protected - at least, offically.
Blue Selaginella fern
Molucca bramble or wild raspberry
On our way home we were lucky to see a cassowary and its chick.
How to get there
From the larger towns of Cairns or Townsville in Queensland, Australia, it is an easy drive north on the main road. This road continues to the Daintree River, where a ferry service running all day will take cars and passengers across to the other side for the price of a ticket. The main road then carries on again to the Daintree village, Cape Tribulation and further up north. It might be good to check the ferry prices and timetable on their website prior to one’s trip.
As the ferry took us across the river in our car, the feeling that overcame me I have not forgotten. The river seemed to act as a border between the society we are used to and the wilderness, like there was an invisible barrier around the rainforest separating it from the outside world. The density of the trees and how they loomed overhead made me really feel like I was setting foot into another - magical - world.
Things to do and see
There are many activities to get up to, including bush walking, swimming in creeks and waterfalls, river trips scouting for crocodiles, great barrier reef trips, horse riding, beach walks etc. I also personally like simply soaking in the wilderness, listening to the sounds of the forest and animals or meditating amongst the trees. Stargazing is possible on a clear night too because there is little light pollution!
When I look at the great trees I like to imagine the vastness of their root systems under the soil - like an underground reflection of the tree canopies. It reminds me of the scientist, Suzanne Simard, who described the amazing underground networks that exist between trees and other organisms like fungi. She has many interesting research articles on the subject.13-17
We intend to go back and further explore this wonderland, after all it is just ”up the road” (500km in Australia is practically a day trip)!
A view of the Daintree river and rainforest.
References
1
Goosem, S. (2002). Update of Original Wet Tropics of Queensland Nomination Dossier. Wet Tropics Management Authority
2
Greenwood, David & Christophel, David. (2005). The origins and Tertiary history of Australian “Tropical” rainforests. In E. Birmingham, C. Dick & C. Moritz (Eds), Tropical Rainforests: Past, Present, and Future (pp.336-373). University of Chicago Press
3
Moreau, C. S., Hugall, A. F., McDonald, K. R., Jamieson, B. G. M., & Moritz, C. (2015). An Ancient Divide in a Contiguous Rainforest: Endemic Earthworms in the Australian Wet Tropics. PLOS ONE, 10(9), e0136943. doi:10.1371/journal.pone.0136943
4
Hallam, A. (1985). A review of Mesozoic climates. Journal of the Geological Society, 142(3), 433–445. doi:10.1144/gsjgs.142.3.0433
5
Veevers, J. J. (2006). Updated Gondwana (Permian–Cretaceous) earth history of Australia. Gondwana Research, 9(3), 231–260. doi:10.1016/j.gr.2005.11.005
6
Greenwood, David. (2000). Australia’s cycad fossils and the antiquity of the Daintree rainforest. Palms & Cycads. 63.
7
VanDerWal, J., Shoo, L. P., & Williams, S. E. (2009). New approaches to understanding late Quaternary climate fluctuations and refugial dynamics in Australian wet tropical rain forests. Journal of Biogeography, 36(2), 291–301. doi:10.1111/j.1365-2699.2008.01993.x
8
Costion, C. M., Edwards, W., Ford, A. J., Metcalfe, D. J., Cross, H. B., Harrington, M. G., … Crayn, D. M. (2014). Using phylogenetic diversity to identify ancient rain forest refugia and diversification zones in a biodiversity hotspot. Diversity and Distributions, 21(3), 279–289. doi:10.1111/ddi.12266
9
Hilbert, D. W., Graham, A., & Hopkins, M. S. (2007). Glacial and interglacial refugia within a long-term rainforest refugium: The Wet Tropics Bioregion of NE Queensland, Australia. Palaeogeography, Palaeoclimatology, Palaeoecology, 251(1), 104–118. doi:10.1016/j.palaeo.2007.02.020
10
BRADFORD, M. G., & WESTCOTT, D. A. (2010). Consequences of southern cassowary (Casuarius casuarius, L.) gut passage and deposition pattern on the germination of rainforest seeds. Austral Ecology, 35(3), 325–333. doi:10.1111/j.1442-9993.2009.02041.x
11
Roberts, P., Buhrich, A., Caetano-Andrade, V., Cosgrove, R., Fairbairn, A., Florin, S. A., … Ferrier, Å. (2021). Reimagining the relationship between Gondwanan forests and Aboriginal land management in Australia’s “Wet Tropics.” iScience, 24(3), 102190. doi:10.1016/j.isci.2021.102190
12
Cosgrove, R., Field, J., & Ferrier, Å. (2007). The archaeology of Australia’s tropical rainforests. Palaeogeography, Palaeoclimatology, Palaeoecology, 251(1), 150–173. doi:10.1016/j.palaeo.2007.02.023
13
Simard, S.W. (2017). The mother tree. K. Verlag and the Haus der Kulturen der Welt, Berlin Edited by Anna-Sophie Springer & Etienne Turpin. The Word for World is Still Forest. ISBN 978-3-9818635-0-5.
14
Simard, S.W., Perry, D.A., Jones, M.D., Myrold, D.D., Durall, D.M., and Molina, R. (1997). Net transfer of carbon between tree species with shared ectomycorrhizal fungi. Nature, 388: 579-582
15
Beiler, K. J., Durall, D. M., Simard, S. W., Maxwell, S. A., & Kretzer, A. M. (2009). Architecture of the wood-wide web: Rhizopogon spp. genets link multiple Douglas-fir cohorts. New Phytologist, 185(2), 543–553. doi:10.1111/j.1469-8137.2009.03069.x
16
Simard, S. W., Beiler, K. J., Bingham, M. A., Deslippe, J. R., Philip, L. J., & Teste, F. P. (2012). Mycorrhizal networks: Mechanisms, ecology and modelling. Fungal Biology Reviews, 26(1), 39–60. doi:10.1016/j.fbr.2012.01.001
17
Simard, S. W. (2018). Mycorrhizal Networks Facilitate Tree Communication, Learning, and Memory. Signaling and Communication in Plants, 191–213. doi:10.1007/978-3-319-75596-0_10
