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.

Bizarre story in the Washington Post

Sometimes truth is weirder than fiction.

Loggers in the Congo... timber harvest in Gabon  (photo by Bill Laurance)

Loggers in the Congo... timber harvest in Gabon (photo by Bill Laurance)

Two days ago (21 November 2014) the Washington Post ran a story entitled "Deforestation vs. daily life: The logging industry in Nigeria is fueling both", by Nicole Crowder, a staff photo editor.

The story was odd for two reasons.  First, via a tapestry of photos shot by Akintunde Akinleye of Reuters, it portrayed Nigeria's rainforest loggers in a remarkably sympathetic manner. 

This is understandable and forgivable.  Loggers are human beings, and like all of us are struggling to survive in an increasingly populous, hard-edged world.  While readily conceding that much forest harvesting in Nigeria is illegal, the images portrayed the loggers as humble battlers, scrabbling to make a living by carving great trees into sawn timber.

Second, and far more remarkably, the story grossly misstated the impact of logging and deforestation in Nigeria.  It claimed that Nigeria lost "just over 2 million hectares of forest annually between 2005-2010 due to agricultural expansion, logging and infrastructure development". 

That figure is massively wrong.  According to data compiled by Professor Matt Hansen from the University of Maryland and Global Forest Watch, forest loss in Nigeria from 2001 to 2012 ranged from a low of around 40,000 hectares per year to a peak of about 150,000 hectares per year.  

One doesn't have to be a math whiz to see that the actual deforestation figures -- or at least the best-available scientific estimates -- are a tiny fraction of those reported in the Washington Post

I was initially bemused by the story because the reported deforestation numbers, if true, would have put Nigeria on par with the Brazilian Amazon in the mid-late 1990s and early 2000s, when that region had the dubious distinction of being the overwhelming epicenter of global forest destruction

I lived and worked in the Amazon for much of that period, and it was a time of catastrophic forest loss and burning -- with palls of smoke from massive fires forcing airports to close and causing sharp spikes in cases of respiratory distress.

If forest destruction in Nigeria was happening as fast as the Post reported -- at a pace that rivaled that in the Amazon -- Nigeria's forests would have vanished in a heartbeat.

At ALERT we pride ourselves on our scientific stripes, but even we make mistakes from time to time.  However, we are not professional journalists.  When a legendary newspaper like the Washington Post gets its reporting so badly wrong, it does give one pause. 

-Bill Laurance