Dr Steven Turton issues a warning on the threats to the Daintree Lowland Rainforest and its World Heritage values.
DR STEVE TURTON
Adjunct Professor, Central Queensland University
The largest area of tropical rainforest in Australia – the so-called Wet Tropics – is a narrow strip along the northeast coast of the continent, totalling about two million hectares. It represents just 0.26% of the continent, but is crammed with hugely diverse landscapes: rainforests, sclerophyll forests, mangrove forests and shrub lands, as well as areas of intensive agriculture and expanding urban rural population centres.
The Wet Tropics are home to a dizzying array of plants and animals. These include at least 663 vertebrate species, 230 butterflies, 135 different dung beetles and a remarkable 222 types of land snail. The area is teeming with more than 4,000 plant species, including 16 of the world’s 28 lineages of primitive flowering plant families.
Daintree Lowland Rainforest: Image by Steven Nowakowski
In all, the Wet Tropics bioregion contains 185 distinct ecosystems. Of these, 18 are officially listed as endangered and 134 are of conservation concern.
Just under half of the region is covered by the Wet Tropics of Queensland World Heritage Area, the world’s second-most-irreplaceable natural world heritage area. A recent analysis listed it as the planet’s sixth-most-irreplaceable protected area in terms of species conservation, and it’s eighth-most-irreplaceable when considering only threatened species.
The rainforests in the Daintree Lowlands between Cape Kimberly in the south and Cape Tribulation in the north are undoubtedly the ‘jewel in the crown’ of the Wet Tropics. These ancient rainforests are globally significant as they represent the largest remaining area of lowland rainforest in Australia’s Wet Tropics, with an area sufficiently large to ensure ongoing evolutionary and ecological processes – an essential requirement for listing as World Heritage by UNESCO. In other parts of the Wet Tropics lowland rainforest was cleared for agriculture and urban development, with only small remnants remaining today.The Daintree National Park and most adjacent ‘undeveloped’ blocks of freehold land contain extraordinary plant biodiversity, with many endemic species. These extremely rare plants are often referred to as ‘green dinosaurs’ because of their archaic characteristics.
Yet despite its global conservation significance, the Wet Tropics was recently described by the International Union for the Conservation of Nature (IUCN) as a World Heritage Area of “significant concern”. This is due to the threat posed to the area’s biodiversity and endemic plants and animals by invasive species, diseases and predicted climate change impacts. Only two other Australian world heritage properties are listed as “of concern”: the Great Barrier Reef and Kakadu National Park.
If a bridge is built across the Daintree River it is certain that more vehicular traffic will occur into the Daintree lowlands, with 24-hour access throughout the year. Research shows that bridges, road construction and road upgrades always result in adverse impacts in tropical forests around the world. For example, we know that bridges and roads act as conduits for invasive plants and animals to penetrate into intact forest areas.
The current Yellow Crazy Ant invasion into rainforests near Cairns is an ecological disaster that could easily be repeated in the Daintree. Judging by the ants’ impacts elsewhere, this is an impending natural catastrophe.
These impacts could be direct – through predation and harassment – or indirect, such as by the removal of invertebrate prey or disruption of processes such as decomposition, pollination and seed dispersal. The potential for knock-on effects in a system as complex and interconnected as the Daintree rainforest is very high.
Building a bridge will bring inevitable pressures for road upgrades, residential and tourism development and will increase road kills of native wildlife, including loss of endangered species like the Southern Cassowary – an important keystone species. Roads also create a plethora of edge effects that can extend up to 100 m or more into adjacent rainforest. Opening of the canopy provides ideal conditions for invasive weeds and animals, and wider rainforest roads have been shown to be a barrier to the movement of some native animals.
Daintree River and ferry: Image by Steven Nowakowski
All of these adverse impacts will result in a decline of presentation values admired by all tourists who visit the Daintree. Such threatening processes will undermine the outstanding universal value of the world heritage area – natural values that have remained remarkably stable for 10s of millions of years could be easily lost forever. If outstanding universal value of World Heritage attributes cannot be maintained due to threatening processes, then the World Heritage Committee of UNESCO has the right to list world heritage properties on the World Heritage In Danger list.
It’s also worth pointing out that the Wet Tropics are a goldmine and the Daintree rainforest is a globally recognised icon. In its 2014-15 report, the Wet Tropics Management Authority calculated that this natural global asset is worth a whopping A$5.2 billion each year – roughly half of it from tourism.
A 2008 report found that the Wet Tropics create the greatest economic benefit of any of Australia’s natural world heritage properties, excluding the Great Barrier Reef. It found that every dollar spent on management costs earned an A$85 return in tourism spending. Even in purely economic terms that makes a pretty compelling case for conservation.
A bridge over the Daintree River will be the beginning of ‘death by a thousand cuts’ for the Daintree rainforest, and a catalyst for UNESCO to place the entire Wet Tropics of Queensland on the in-Danger List.
The environmental and economic impacts of such an unnecessary project are not worth gambling within the new COVID-19 world!❞
Republished here with the permission of Dr Steve Turton
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