Stealing the Rain from a Rainforest

ALERT’s Susan Laurance, from James Cook University in Australia, is leading an ambitious, million-dollar study to understand how droughts affect tropical rainforests.  Here she tells us about this challenging project and why it is so important:

Right now, much of the world is struggling to cope with a ‘Godzilla’ El Niño drought

The drought has been merciless, causing catastrophic fires and haze across much of Southeast Asia, unprecedented droughts and wildfires in western North America, and mass starvation from crop failure in New Guinea

Fiery future?

And there’s good reason to think future droughts might even be worse. 

First, leading computer simulations suggest global warming could strengthen future El Niño events and increase the frequency of serious heat waves.

Second, apparently new climate dynamics are appearing on Earth that could threaten large areas of rainforest.  Most notable among these are the unprecedented Amazon droughts – driven by exceptionally high sea-surface temperatures in the Atlantic Ocean – that occurred in 2005 and again in 2010.

Finally, human land-uses are making rainforests far more vulnerable to droughts and fire.  For instance, forests that have been logged or fragmented are drier and have much heavier loads of flammable slash than do pristine forests.

And as new roads proliferate almost everywhere, so do the number of human-caused ignition sources.  Even ecosystems where fire was once foreign — such as the world’s deep rainforests — now burn with increasing regularity.

All this means that it’s vital to understand how droughts will affect rainforests – the world’s most biologically diverse and carbon-rich ecosystems.

Big science for a big problem

As I detail in a recent article in Australasian Science (which you can download here), my colleagues and I have recently set up some 3,000 clear plastic panels to create a ‘raincoat for a rainforest’ – inducing an artificial drought over several thousand square meters of the famous Daintree region in north Queensland, Australia.

A big advantage of our experiment – one of the few ever to study rainforest droughts in this way – is that we have a 47-meter-tall canopy crane at the site, so we can assess plant and animal responses at all vertical levels of the forest, from the ground to the tops of the most towering trees.

Our study is comparative: we want to understand how different groups of plants, such as various functional groups of trees, vines, shrubs, forbs, and epiphytes, are affected by drought.

We are looking at the survival, growth, and physiology of these plants in a variety of ways, as well as at the forest soil and microclimate.  Others are studying how insects and other fauna are affected by the drought.

Among our key goals is determining whether big trees are especially vulnerable to droughts, as suggested by recent research.   If so, then this could have profound implications – because big trees store huge amounts of carbon and provide food and shelter for an entire zoo of animal species.

We also want to learn whether certain kinds of plants have strategies – such as special water-carrying vessels in their tissues or other physiological tricks – that allow them to better survive droughts.  If so, these ‘drought winners’ could increasingly dominate forests if droughts become more intense in the future.

Not easy – but worth it

This study has not been easy – in truth it’s been a logistical nightmare to steal the rain from a rainforest.  But the study is now fully set up, and in the end we think it will be worth all the sweat and hard work. 

Rainforests are the biologically richest environments on Earth.  And if we’re going to subject them to more Godzilla-like droughts, then we need to know how they’ll respond – and whether they can sustain their stunning biodiversity into the future.

Could disease be driving extinctions of Australian mammals?

Across the vast savannas of northern Australia, mammal populations are collapsing.  Areas that once sustained healthy populations of native mammals are now ecological deserts, virtually devoid of life.  Three researchers from James Cook University, Sandra Abell, Penny van Oosterzee, and Noel Preece, believe that deadly pathogens might be partly responsible for this ongoing calamity:

Brush-tailed bettong -- a critter we don't want to lose.

Brush-tailed bettong -- a critter we don't want to lose.

One third of all mammal extinctions worldwide have occurred in Australia.  Here, 24 mammal species have been wiped out since European arrival -- and that number is still rising.

Loss of habitat, altered fire regimes, and predation by feral cats are all implicated in the recent mammal declines. The role of disease, however, is an understudied but likely contributing factor.

Disease can be deadly for wildlife.  For instance, facial tumor disease is rapidly killing off populations of the Tasmanian Devil.  Trypanosomiasis, introduced by black rats brought by sailing ships, drove the demise of two native species of rainforest rats on Christmas Island, in the Indian Ocean.

Tasmanian Devil with facial tumors -- not a pleasant way to go.

Tasmanian Devil with facial tumors -- not a pleasant way to go.

Now key populations of the Northern Bettong, an attractive wallaby-like animal endemic to north Queensland, is crashing possibly to extinction.

And just this week, endangered Saiga antelopes in Uzbekistan in Asia were reported to have suddenly collapsed, due to the combined effects of climate change and normally harmless bacteria that have evidently become lethal pathogens to the stressed animals.

Saiga Antelope -- another victim of catastrophic disease?

Saiga Antelope -- another victim of catastrophic disease?

We and colleagues have formed a multi-disciplinary group to tackle these declines.  We call ourselves the North Australia Wildlife Decline Disease Investigators.  Our acronym, NAWDDI, rhymes with "naughty".

Our group combines top wildlife ecologists and experts in wildlife disease, including one of the world’s leading experts in wildlife pathogens, Dr Peter Daszak, Director of the EcoHealth Alliance.

NAWDDI is being guided by hard-won lessons learned from the front line of the battle to save imperiled species.

One example is the Brush-tailed Bettong.  Thought to be secure in southwestern Australia, 90 percent of its population has vanished alarmingly over the last decade.  Valiant attempts to understand and halt its decline are providing valuable new insights for conservationists.

NAWDDI is working on a variety of fronts -- from advising on global policy to developing field protocols to make disease investigation a standard practice in researching declines of wild populations.

Disease must be considered early as a potential cause of the rapid and severe mammal declines in northern Australia.  We know that virulent pathogens have caused widespread extinctions or declines of many species worldwide -- from frogs, to Hawaiian birds, to African ungulates and apes, to North American bats.

Pathogens such as the chytrid fungus have driven at least 200 frog species to extinction.

Pathogens such as the chytrid fungus have driven at least 200 frog species to extinction.

Early detection saves money and time -- and could help us avoid the anguish of having to watch helplessly as charismatic mammals like the Brush-tailed Bettong follow the path of three of its sister species to extinction.


Mysterious black leopards finally reveal their spots

Researchers have devised a clever technique to tell black leopards apart -- a trick that may end up saving their skins.  

Jet-black in color to the naked eye

Jet-black in color to the naked eye

The researchers have been studying leopards on the Malay Peninsula -- where almost all of the big cats are jet black. 

Elsewhere across its range in Africa and Asia, the leopard is pale colored with distinctive black spots.

Experts have no idea why the Malay leopards are black and, until recently, could not tell them apart, hindering research and conservation efforts.

But the researchers have now devised a simple method to solve the problem by manipulating the mechanism of automatic cameras.  Such cameras are increasingly being used to study animals in the wild.

“Most automatic cameras have an infrared flash, but it’s only activated at night”, said Gopalasamy Reuben Clements, an ALERT member and coauthor from James Cook University in Australia. 

“However, by blocking the camera’s light sensor, we can fool the camera into thinking it’s night even during the day, so it always flashes,” said Clements.

With the infrared flash firing, the seemingly black leopards suddenly showed complex patterns of spotting.  These spots could be used to distinguish different animals, and help estimate the population size of the species.

Automatic photos of black leopards without and with an infrared flash  (images (c) Rimba).

Automatic photos of black leopards without and with an infrared flash (images (c) Rimba).

The researchers tested this method in northeastern Peninsular Malaysia.  “We found we could accurately identify 94% of the animals,” said Clements.  “This will allow us to study and monitor this population over time, which is critical for its conservation.”

The researchers want to use their new method to study black leopards in other parts of Peninsular Malaysia -- where there is abundant prey but few leopards are seen. 

It’s thought widespread poaching is largely to blame. 

“Many dead leopards bearing injuries inflicted by wire snares have been discovered in Malaysia,” said ALERT director and coauthor Bill Laurance, also from James Cook University.

Laurance said that leopard skins and body parts are increasingly showing up in wildlife-trading markets in places such as on the Myanmar-China border.

At the same time, suitable leopard habitats are disappearing faster in Malaysia than perhaps anywhere else in the world, as forests are felled for timber and replaced with oil palm and rubber plantations.

“Understanding how leopards are faring in an increasingly human-dominated world is vital,” said Laurie Hedges from the University of Nottingham-Malaysia, who was lead author of the study, published in the Journal of Wildlife Management

“This new approach gives us a novel tool to help save this unique and endangered animal,” said Hedges.

Deadly Australian drop bears are much more abundant than previously thought

A new analysis in the respected journal Australian Geographer suggests that Drop Bears -- a predatory and highly feared relative of the Koala Bear -- are much more common and widely distributed in Australia than was previously believed.

(a) An adult Drop Bear; (b) A Drop Bear attacking its prey.

(a) An adult Drop Bear; (b) A Drop Bear attacking its prey.

The Drop Bear (Thylarctos plummetus) is known to favor dense forests and has been blamed in the past for the unexplained disappearances of several tourists and hikers in Australia.  It is predominantly arboreal and typically attacks by dropping onto its prey from above.

The study, conducted by Volker Janssen at the University of Tasmania, used sophisticated remote-sensing and spatial modelling techniques to estimate the geographic range of the Drop Bear. 

The species was formerly thought to be confined to just a few locales, but it now appears to be widely distributed across Eastern Australia and parts of the far north and far southwest of the continent. 

"I have to say this study makes me pretty nervous," said Miriam Goosem, a field biologist at James Cook University in north Queensland.  "I work in a lot of dense forests and if Drop Bears really are that common, then my job suddenly seems quite a bit more dangerous."

"People tend to think of the Saltwater Crocodile as our most dangerous species, and I suppose that's true if you're near the water.  But in forests, the Drop Bear is definitely the animal that scares me the most," said Dr Goosem.

"I think we need to get the word out to tourists, as many of them don't know about Drop Bears," said Goosem. 

"I'd say if you're coming to Australia and plan to go hiking in the forest, be afraid.  Be VERY afraid."

 

 

Momentous changes ahead for the tropics

The world's tropical regions will be the epicenter of change in global economies, population growth, and environment.  That's the take-home message of a groundbreaking report that forecasts massive changes this century in the tropics.

Huge changes ahead...  (from Mongabay)

Huge changes ahead... (from Mongabay)

The ambitious State of the Tropics Report was launched last week in Burma and Singapore, in a special televised event. 

The report was kicked off by Nobel Laureate and Burmese leader Aung San Suu Kyi with assistance from Sandra Harding, the Vice-Chancellor of James Cook University in Australia, and a panel of experts that included ALERT director Bill Laurance

Produced by a coalition of 12 universities and research institutes from the Asia-Pacific, Africa, and Latin America, the State of the Tropics report sees dramatic changes ahead for the world's tropical regions:

- by the latter part of this century, the population of tropical nations will swell by over 3 billion additional people, with Africa's population nearly quadrupling

- food demand in tropical and developing nations will double by mid-century

- by 2050, two-thirds of all children will live in the tropics

- land-use pressures will intensify sharply because of a dire need to increase food and biofuel production in the tropics

- as the century unfolds, tropical nations will increasingly be the centers of global economic growth and also rising geopolitical conflicts over land, water, and natural resources

- the tropics sustains 80% of all species, many of which will be imperiled by rising habitat loss, climate change, and other perils.

The State of the Tropics report is the first comprehensive effort to project change across the entire tropical region -- which will increasingly become a key driver of social, economic, and environmental change globally.