Environment / The regeneration of the Four Mile Beach foreshore vegetation

ANDRE LEU

The first mariners did not describe the vegetation on Four Mile Beach. As part of the research for this article I went through all the accounts I could find, beginning with Cook, Banks and Parkinson in 1770. I could not find any mention of the Four Mile foreshore.

The first detailed reports of the vegetation the region around Island Point were given by George Elphingstone Dalrymple in 1873. He named Island Point and was first documented European to sail upon the Mossman and Daintree Rivers. He described the hills and mountains as jungle-clad with some patches of well wooded open forests with grassy understories, however he did not describe the vegetation cover on Four Mile Beach or Island Point.

In April 1877 Christie Palmerston found the path from the Hodgkinson gold fields to Island Point by following an aboriginal trail down the Mowbray River and reported this to the Queensland Government.

An expedition was sent out in June 1877, to confirm if Palmerston’s path was suitable for wheeled vehicle traffic. It was led by William Oswald Hodgkinson, an experienced trail-blazing explorer, who had been part of the Burke and Wills, and other expeditions. His friend, James Venture Mulligan, who discovered the Palmer and Hodgkinson gold fields named the Hodgkinson River after him.

Most of the rainforest species cannot tolerate fire and die when burnt. If there is enough soil moisture and the fire is a small cool winter burn, it generally extinguishes when it reaches the rainforest edge, without damaging the rainforest, because of the lack of readily flammable material.

Indigenous Australians practiced cool burns and created a mosaic of ecosystem types. Their burning did not destroy large areas of rainforest In the Wet Tropics. They co-existed with the rainforest for thousands of years.

However, this changed dramatically with the arrival of Europeans who actively cut down trees and used fire to kill rainforests to create cleared land for agriculture. The bulk of the rainforests in Australia were cleared by fire, not by the axe. Unfortunately fire is still being used to clear the last great rainforests of the Americas, Asia and Africa.

Rainforests are closed canopy forests. The dense canopy stops grass and other full sun species from growing under the trees, because they get shaded out. The cutting of trees for timber and firewood opens the canopy and allows grass to grow inside the forest. Dry grass is highly flammable and when burnt, the high temperatures kill the rainforest trees. 

Port Douglas was no different. Fire killed the coastal rainforest. The constant burning prevented the rainforest from regenerating and instead species that tolerate fire such as Northern Wattle (Acacia crassicarpa),  New Guinea Wattle (Acacia aulacocarpa), Beach Casuarina (Casuarina equisetifolia) and Stocking Gum (Corymbia tessellaris) began to dominate and form a new type of ecosystem.

Where there is good underground water, the Weeping Paperbark (Melaleuca leucadendra) survived because their thick papery bark protected them from fires.  The largest of these trees are some of the only survivors from the original pre-1877 ecosystem. These Melaleuca trees can still be found in the Solander Boulevard, Reef St, Langley St and Barrier St areas. The signs of fire can be seen on some of them.

All of them should be fully protected and preserved as old historical trees. It is the worst sort of historical and environmental vandalism to cut down these old giants, and there should be severe penalties for destroying or damaging them.

I first inspected Four Mile Beach in 1971 and it only contained a limited number of small fire resistant species. Most of the trees were small wattles, (Acacia Crassicarpa and Acacia aulacocarpa) with some Beach Casuarina (Casuarina equisetifolia) especially on the coastal fringe along with a few clumps of Cardwell Cabbage (Scaevola taccada).

Stocking gums (Corymbia tessellaris)  grew further inland. Some Spinifex sericeus grow on the dunes along with Ipomoea pes-caprea, Canavalia rosea, and Cassytha filiformis.

Large remnant paperbarks (Melaleuca leucadendra) with some Sea Hibiscus (Hibiscus tiliaceus) grew in the areas with ground water.

A survey conducted by Geoff Tracey and Len Webb in 1975 describes the area as Coastal Beach Ridges and Swales (the yellow section of the map below). The Wet Tropics gives the species composition as Ipomoea pes-caprea, Canavalia rosea, Spinifex sericeus and Cassytha filiformis.  This gives way to a low, and often sparse shrub land comprising, amongst other species, Scaevola taccada, Premna serratifolia, Hibiscus tiliaceus, Acacia crassicarpa and Casuarina equisetifolia.

This ecosystem type is a result of fire. Wet Tropics management states that it needs regular burning for it to be maintained.

Port Douglas experienced decades of decline after Cairns became the major port due to the opening of the railway to Mareeba in 1896.  The decline continued when the sugar wharf was replaced by the bulk sugar terminal in Cairns. The cheap land became popular for holiday homes for recreational fishing and also as permanent homes for the commercial fishing fleet. Consequently, Port Douglas began to slowly grow again in the 1970s  and was largely a fishing village. The increase in residential houses along Four Mile Beach led to a reduction in the annual burning of vegetation and started the process of regeneration in limited areas.

The Sheraton Grand Mirage Resort was officially opened on Four Mile Beach in October 1987 by Christopher Skase.  Almost overnight, Port Douglas changed from a quiet fishing village to a world renowned international tourism destination. A real estate boom resulted in the construction of residential homes and holiday accommodation.

Much of the existing vegetation was cleared for the Mirage and other developments as well as for housing. The regular burning of the vegetation ceased, and the remnant vegetation on the foreshore could regenerate back to littoral rainforest.

The vegetation map below was produced 30 years after Tracey and Webb by the Stantons in 2005. It shows most of the vegetation has been cleared, and that the vegetation types have changed. The most significant stand is the remnant Melaleuca leucadendra forest in the Solander Boulevard and Reef St foreshores (highlighted in light blue in the map below).

The small remnant areas of the coastal foreshore especially in the areas from Solander Boulevard to the Mowbray, started the process of regenerating back to the closed canopy littoral rainforest described by Hodgkinson in 1877.

Fifteen years later (2020) this process of succession from a secondary to a primary ecosystem is ongoing.  Now that a canopy is forming and closing over the new forest, the next generation of new species is growing as part of the succession into a primary forest. This will still take another century, or more. Most of the trees in this forest are still quite young compared to similar old growth forests such as those along the Daintree Coast. The future generation of plants are now germinating and growing under the new canopy and will, over decades, change the species composition of this remnant forest.

It will still take a few centuries for this forest to fully regenerate to the old growth climax forest that was destroyed in 1877. Some of the larger long-lived trees such as Mastwoods and Banyans, after forty years of not being burnt, are starting to grow into good-sized trees, however it will take another hundred years or so before they reach the impressive sizes that can be found in old growth littoral rainforests.

I have deliberately chosen to stay away from the issue of exotic species and their roles in the regeneration process because it is complex and controversial. The critical issue now is to protect these remnant areas by minimising human disturbance and let them get on with the job of regenerating.

Nature will always regenerate ecosystems after they have been damaged, and she has been doing a great job in regenerating this ecosystem. We can help her by not disturbing and damaging her great work.