The Magic of the Daintree

The legendary Sir David Attenborough once remarked that one of his favourite places in the world was Far North Queensland, and added further that the Cape Tribulation – Daintree area was among one of the most special places he had ever been, because one is able to experience both the reef and the rainforest within a short distance.

As a natural historian having travelled the world to explore and showcase beautiful places, Sir Attenborough’s perspective is surely one to take seriously.

It is true that the Daintree has already garnered the reputation for being “Where the rainforest meets the reef”, and also there are Cassowaries, which are also crowd-pleasers. But what is actually so special and unique about the Daintree?

The Great Barrier Reef stretches over 2300 km along the Queensland coast, and so rainforests actually do meet the reef elsewhere in the region, and cassowaries may be encountered in various other parts of the Australian Wet Tropics, and even also in Papua New Guinea and Indonesia.

This leaves us with rainforests, and although the Australian Wet Tropics is famous in Australia for rainforest, this article aims to show that it is what is found within the rainforests of the Daintree that makes the place truly extraordinary.

Forest Fairyland

The Daintree National Park is divided into two sections: the southern section comprises of the Mossman Gorge area, and the northern section, which is the focus of this post, is the Cape Tribulation section, bound roughly by the Daintree river in the south and the Bloomfield river in the north.

Cape Tribulation was so named because the British navigator Captain James Cook’s encountered various hardships at the namesake location after his ship ran aground there. Fortunately, getting to the Cape Tribulation section of the Daintree National Park is a pleasure these days.

From Cairns it takes up to one and a half hours of scenic northbound driving through coastal roads, small towns, canefields, and mountain vistas to reach the river crossing at the Daintree River. Then there is a short barge trip across the river and upon arriving at the other bank, the world of everyday life peels away, and a forest fairyland realm begins.

Many visitors would make the Daintree pilgrimage with the hopes to see a Cassowary – a setup for a myopic traveller’s experience!

To put things in proper perspective, Charles Darwin once commented that “…a traveller should be a botanist, for in all views plants form the chief embellishment”.
So for anyone who would heed the sermon from the Pope of Science and dedicate a moment to observe intently, the textures of the Daintree forests will unravel before one’s eyes.

The vegetation of the Daintree is not a uniform wall of green – at different points along the drive from the start of the Daintree River to the Bloomfield River, vegetation types transition into one another almost seamlessly, like a green-jewelled living tapestry.

At the Daintree River crossing, both banks are lined with mangroves. Few would imagine that the Daintree River is actually one of the most mangrove species-rich estuaries in the world, harbouring some 31 species of mangroves (almost half of the total of 69 mangrove species in the world).

Mangroves line the Daintree River – these are among some of the most pristine mangroves in the world

The Daintree mangroves are in a pristine condition, and harbours a wide variety of mangrove-associated plants. It is easy therefore to espy a large variety of orchids and other interesting epiphytic Myrmecodia ant-plants (plants with adaptations for housing ants) that hang from the trunks of the mangrove trees whilst exploring the Daintree mangroves on river ferry tours, or during self-guided walking tours at a number of localities.

Mangrove forests transition into freshwater swamp forest in places where salt water do not infiltrate, but where soils are still poorly drained. Here is where giant weeping paperbark trees (Melaleuca leucadendra) with stem girths of over a meter predominate, but not just. Grand screwpines (Pandanus spp.) with long straplike leaves shelter beneath and dramatize the spaces beneath these Melaleucan canopies. Colonies of Alexander Palms (Archontophoenix alexandrae) break the canopies with delightful grace. Who would have imagined that muddy swamps could exhibit such pomp.

Freshwater swamp forests just meters from coastal forests in the Daintree

Even fewer would have imagined that in these swamps harbour what must be the largest species of sedge in the world – Scirpodendron ghaeri. Because of the long saw-edged straplike leaves, most would probably mistake these 2-4m shrub-like sedge monstrosities for young screwpines.

Out seaward, soils become sandier and better drained, mangroves and swamp forests are replaced by littoral forests and sandy beach vegetation. Here are some of the most untouched tropical beach forest vegetation in the world, pushing the seaward gauntlet with native inhabitants such as massive Alexandrian Laurels (Calophyllum inophyllum), Beach Barringtonias (Barringtonia asiatica) and Coastal She-oaks (Casuarina equisetifolia).

Think not for a moment that the Daintree is a forest chorus without an interlude.

Out on more exposed locations coastal rocky locations such as at Cape Tribulation, one does encounter a sunny respite from the shade of the forest in coastal woodlands amongst the familiar company of gum and bloodwood trees.

But we must venture inland to find where the true treasures of the Daintree lie. As we make an imaginary altitudinal journey we see an expanse of humid lowland rainforests, the most continuous and unbroken expense of rainforest there is in Australia.

The famed “Big Fig” of Cape Tribulation

Heading up higher towards the mountaintops such as Thornton Peak and the surrounding mountain ranges, the forest vegetation becomes simpler in structure. Trees become lower-statured, smaller-leaved, and shrub-like, and festooned with orchids and other epiphytes, and the understorey becomes progressively more fern and moss dominated. Finally at the highest parts of these mountain stations, trees give out to patches of scrub amongst boulders.

The humid lowlands is our focus, as this is the mainstay of the Daintree experience. The esteemed Australian ecologist Jeff Tracey once described the lowland rainforests of the region as “the prime development of rainforest in Australia”.

Here, trees are the most conspicuous lifeforms. In such environments and other tropical regions in the world, such forests and their trees constitute the largest carbon storehouse on the planet.

In the Daintree, tall and large-girthed hardwood trees of red tulip oak, red cedar, spurwood, black bean, may tower over 45m.

At the base of some of these trees are tall plank buttresses so characteristic of tropical trees.

Then outsizing these giants in stature or girth are the occasional Brobdingnagian canopy emergents of Milky Pines (Alstonia scholaris), or colossal strangling fig trees which now stand as a living outer cast of their previous “victims”.

Other trees like the Yellow Mahogany (Dysoxylum parasiticum) and Bumpy satinash (Syzygium cormiflorum) present yet another archetype of tropical forests – the curious bearing of flowers and fruits on their trunks.

This phenomenon, known as cauliflory, was perplexing to some of the earliest Europeans who explored tropical regions. Some of the best educated among them innocently believed that there was a leafless parasite residing within the trees and bursting out of the bark of their hosts in an Aliens-like fashion when the time came to flower.

Palm trees, known in botany circles as the “Princes” of the botanical world, are another conspicuous component of the canopy and midstorey of these forests. The Daintree is famous for Fan Palms (Licuala ramsayi), which in some places dominate the canopy and whose giant overlapping fronds choreograph a postcard picture perfect scene. Black Palms (Normanbya normanbyi) common only in the Daintree, have one of the hardest wood of all palm species, and were once used by tribespeople to make clapsticks. Other palm-like trees such as tree ferns (Cyathea spp.) and tree cycads add a touch of antiquity, sophistication and texture to the rainforest understorey.

Trees are just one of the diverse lifeforms in the Daintree tropical forests. As much as possible, other lifeforms make use of the spaces beneath the canopy. Lianas such as Blood Vines (Austrosteenisia spp.) with twisted stems attain monstrous thigh-size stem diameters that Tarzan might have difficulty gripping onto.

“Wait-a-While” climbing palms abound, and interweave themselves throughout the vertical and horizontal spaces between tree boles. “Wait-a-Whiles” are so named because once it is hard to free yourself once you get entangled amongst their evil-looking recurved grapnels.

Some plants live on the trees themselves.

Epiphytes such as Birds nest ferns, elk horn ferns, tassel ferns and orchids enjoy highrise living in the tall branches or trunks of their arboreal hosts. Some epiphytes begin life differently, as root climbers.

From lowly stations in the forest floor they inch up the trees towards the light using roots from their stems to get a griphold on the bark of their hosts.

Yet other tree dwellers use their hosts not just for support, but also tap into their hosts’ vascular system for nutrients via parasitic connections.

The dim forest understorey realm offer niches for shade-tolerant plant lifeforms. How dreary would tropical rainforests be without a complement shrubs with flowers and fruits that one could admire at a comfortable eye level.

To complete our verbal diorama of lowland rainforests, thread lightly upon the forest floor and search for the myraid understorey herbs, native gingers, leafless root parasites, ferns and mosses eke out a living through filtered light, or in slightly brighter niches in soil or rocks by stream banks.

Here and there, the seedlings of what-will-be-giant-trees cluster, living on sunflecks and awaiting the lottery demise and fall of a giant tree nearby to release them from their shade-imposed dwarfism.

Botanical Ark

Having established the microcosmography of the Daintree rainforest, we can really examine why the Daintree matter. Deeper we must delve into what might seem to be the intractable realms of botany – and explore some delectable minutia of the Daintree flora.

The Daintree is truly a place of botanical paradise. Over 1500 species of land plants are found just within this small area.

Endemism is also a common theme, but not just. The Wet Tropics region alone is sprawling with plants found nowhere else in the world, but the Daintree has around 30 such species found nowhere even in the Wet Tropics.

In fact, some of these species are very rare and endangered and are restricted in their distribution to single localities, typically along certain waterways such as Cooper Creek, Noah Creek, and Oliver Creek.
This has led biogeographers to suggest that these creeks are pockets of refugia areas for rainforest species in historical periods when the general climate of the broader region was inimical to rainforest.

The endangered Daintree Gardenia

The Daintree is a literal botanical ark! To cover all these Daintree endemic species would be well beyond the scope of this post, but a few we must present.

The Marrdja Botanical Walk is a well-signed looped walk where one can visit Oliver Creek and start to appreciate Daintree’s green gems, and also experience some of the Daintree’s mangroves on foot.

Marrdja is in fact an indigenous Kuku Yalanji name for rainforest walk.

A number of rare plants can be encountered here, including the rather ornamental and endangered Daintree Gardenia (Gardenia actinocarpa). This understorey shrub has large white showy flowers and interesting ribbed fruits, and has great potential for cultivation.

The tree of Noah!!! – a tropical witch hazel.

Not far from Oliver Creek is another creek system, Noah Creek, which has its own cache of botanical jewels.

Here we find Noahdendron (Noahdendron nicholaisii), which literally means the Noah (Creek) tree.

Noahdendron produces an attractive pendant spike of pink flowers, and is a tropical member of a family of mostly temperate plants known as witch hazels.

Another namesake tree is the rare Noah’s Tamarind (Lepiderema hirsuta), a native relative of the lychee which at the opportune growing season sends forth marvellous sprays of purple young leaves.

Upstream along Noah Creek, one will also encounter the distinctive Daintree Pine (Gymnostoma australianum).

The endemic (and badly-named) Daintree Pine occurs along rivers in the Daintree

The tree resembles, but is not a real pine. Instead, it is a relative of the (equally badly named) coastal she-oak tree.

The Daintree Pine occurs in a few locations in the Thornton Peak area, and on Noah Creek where one might encounter a copse of trees huddling together in a midstream island, and wonder at the precariousness of their existence.

Cooper Creek is yet another locational treasure chest where botanical rarities abound, such as the mysterious and endangered satinash tree called Syzygium glenum. This little-known satinash cuts an imposing figure of a large and often multiple-stemmed tree with brownish pear-shaped fruits. The fruits are indeed a curiosity.

Unlike other satinashes, the fruits of S. glenum are hard and leathery, and probably not particularly edible. Whether Cassowaries disperse the seeds are also not certain, but what is certain is that the tree is apparently found in only a single population in Cooper Creek with a few mature trees. The specific epiphet is derived from the Greek word glenos, alluding to “something to stare at, wonder”, in reference to the interesting fruit.

The gorgeous flower of the Daintree Penda (Xanthostemon formosum)

Another Cooper Creek gem is Xanthostemon formosum, a little known relative of the very common and also horticulturally renowned native Golden Penda (Xanthostemon chrysanthus).

Both the Cooper Creek Penda and the Golden Penda occur in similar environments beside rivers and streams, but one must wonder what predisposes one to seem so vulnerable and restricted and the other so successful and widespread. Could the future survival of the Cooper Creek Penda perhaps be safeguarded too by cultivation?

It would be unforgivable to talk about rainforest in the Wet Tropics without mentioning “primitive” or “ancient” plants, for which the region is famous. But contrary to popular imagination, these species are not primitive in the sense that they have existed for millions of years since the time of the dinosaurs. Rather, these plants are representatives of early lineages of seed-bearing plants.

Idiosyncratic Idiospermum makes idiots of botanists who try to idealize

With this distinction in mind, the Daintree has a fair share of “primitives”. The Idiot fruit (Idiospermum australiense) is one example, and belongs to the Calycanthaceae, a plant family that arose very early in the history of plant evolution.

The idiot fruit is so named because the 3 or sometimes 4 compartments (known as seed leaves or cotyledons) of the large seed was extremely perplexing to botanists. In days of pre-molecular botany, flowering plants were considered to have either one (mono-) or two (di-) cotyledons, and this was a major taxonomic system for classifying plants.

Needless to say the 4 cotyledons of the idiot fruit was a curiosity if not a source of confusion. The closest relatives of this tree are found in the warm temperate zones of America and eastern Asia.

Another group of “primitive” plants are those belonging to the Laurel family. This family comprise a species-rich of trees that are widespread across the tropics.

In the Wet Tropics, native laurels comprise almost 100 species trees and many are widespread and common in the region, but in the Daintree there are few species such as the Noah’s Walnut (Endiandra microneura) and Cooper Creek Walnut (E. cooperana) and Gray’s Walnut (E. grayi) that are found nowhere else.

Bettles pollinate the flower of the endemic Cooper Creek Haplostichanthus

Closely related to the laurels also is the Custard Apple family (Annonaceae), of which the Daintree harbours a fair number of representatives.

One species restricted to the Daintree is the Cooper Creek Haplostichanthus (Haplostichanthus ramiflorus), a little known shrub of the rainforest understorey. This species, like other members of the Annonaceae, still uphold an ancient alliance with beetles, which serve as pollinators of their flowers.

Animal refuge

The botanical treasures of the Daintree could fill a dedicated book and has been the focus of this post, but we must pay our dues to the marvellous animals that make the Daintree their abode. Even though few animals are restricted to the Daintree, the Daintree forests and the mountain ranges within the Daintree National Park still represent an important refuge for many of these species. We touch briefly on just the birds, mammals, reptiles and amphibians.

Sightings of the endangered and flightless Cassowary are always something to look forward to, as are the over 400 other species of flight-abled birds. The Daintree is also home to a wide variety of mammals such as the Bennetts tree kangaroo, bandicoots, echidnas, sugar gliders, possums, quolls, antechinuses, platypuses, phascogales, pademelons, rare bats and rats.

Over 20 reptile species inhabit the Daintree, including the estuarine crocodile, the saw-shelled turtle, various species of snakes, the lace monitor lizard, boyd’s forest dragon, and a surprising variety of almost 20 species of skinks. Among the skinks, the Thornton Peak Calyptotis (Calyptotis thorntonensis) is one with a very restricted distribution to some area on Thornton Peak.

The amphibians of the Daintree are perhaps the most vulnerable group of animals. Around 25 species of frogs are found in the National park, and many of these are confined to the higher mountain areas, where the vicissitudes of climate change may bear down on them harshly.

Epilogue

For the small area it occupies, the Daintree National Park must rank among one of the most diverse spots on earth, not just in species but also in the range of habitats that can be encountered within a short drive just between the Daintree and Bloomfield Rivers. Indeed, the Daintree rainforests represents Australia’s last bastion of what used to cover a much larger part of the Australian tropics.

While humid rainforests in the Daintree might seem to cover a vast continuous expense (as far as Australian rainforests goes), this may well change in the decades to come, if the tides of climate change bring on waves of “hotter and drier for longer”.

But wallow not for a moment in any mood of angst and helplessness imagining what may come.

In the forest fairyland that is the Daintree, there is only one votive – to become keenly cognizant in each moment of exploration of as many of the beautiful forms that one may encounter, and pursue to the deepest depths where this appreciation can take us.

(Co-authored by David Tng and Deborah Apgaua – A version of this writing was published as a popular article in the Oct-Nov 2017 issue of the Queensland’s PROTECTED magazine [download here])

References
Craven, L. A. (2003). Four new species of Syzygium (Myrtaceae) from Australia. Blumea, 48, 479-488.
Edwards, W. et al. (2001). Idiosyncratic phenomenon of regeneration from cotyledons in the idiot fruit tree, Idiospermum australiense. Austral Ecology, 26, 254-258.
Prider, J. N., & Christophel, D. C. (2000). Distributional ecology of Gymnostoma australianum (Casuarinaceae), a putative palaeoendemic of Australian wet tropic forests. Australian Journal of Botany, 48, 427-434.
Rupert, R. (1986) Daintree, Where the Rainforest Meets the Reef, Our Last Paradise at Risk. Kevin Weldon Production, Australia.
Tng, D. Y. P., et al. (2016) Vegetation and floristics of a lowland tropical rainforest in northeast Australia. Biodiversity Data Journal, 4, e7599. doi: 10.3897/BDJ.4.e7599.
Tracey, J. G. (1982). Vegetation of the humid tropical region of north Queensland. CSIRO.
Wilson, P. G. (1990). A revision of the genus Xanthostemon (Myrtaceae) in Australia. Telopea, 3, 451-476.