Habitat fragmentation is having "terrifying" effects on ecosystems

A global surge in habitat fragmentation is simply "terrifying", according to two dozen of the world's top ecologists. 

A forest elephant... not many places to hide anymore.

A forest elephant... not many places to hide anymore.

The authors make this assertion in a paper (which you can download free here) in the leading journal Science Express
 
The paper was led by Nick Haddad from North Carolina State University, and includes ALERT members Thomas Lovejoy and Bill Laurance as coauthors.

The study contrasts all of the major experimental studies of habitat fragmentation that have ever been conducted -- including the Biological Dynamics of Forest Fragments Project in central Amazonia, which was founded by Lovejoy in 1979 and is the largest and longest-running of all the experiments.

The study concludes that, almost inevitably, fragmentation has a severe effect on species diversity and ecological functioning -- in ecosystems ranging from rainforests to woodlands to isolated patches of moss.

One of the key drivers of change in ecosystems is edge effects -- physical and biological changes associated with the abrupt, artificial edges of habitat fragments.  For instance, you often see more tree mortality, fires, microclimatic stresses, and invasive species near edges.

The study concluded that 70 percent of all the world’s forests are now within one kilometer of a forest edge, and 20 percent is within a football field of an edge.
 
“There’s really only two big blocks of forest surviving on Earth today,” said Professor Haddad.  “That’s the Amazon and Africa’s Congo Basin.”
 
And even those great forests are under assault.  For example, loggers have bulldozed more than 50,000 kilometers of new roads into the Congo since the year 2000.  As a result, the forests have been invaded by poachers with modern weapons, who have killed off two-thirds of the world’s forest elephants for their valuable ivory tusks.
 
The study was highlighted in an excellent article in the famous New Yorker magazine.  It underscores that fact that roads really are the biggest danger.

Once a road cuts into a forest, we often see an influx of illegal colonists, loggers, poachers and miners, especially in developing nations where the rule of law is often limited.
 
In the Amazon, for instance, 95 percent of all deforestation occurs within five kilometers of a road

The take-home message is obvious: If we’re going to preserve parts of wild nature for future generations, we simply must keep the roads out.
 

ALERT confronts US Ambassador about roads

U.S. Ambassador Kenneth M. Quinn loves roads.  He sees them as the salvation for many of the world's ills.

If only we had more roads, he argues in a recent essay in National Geographic Online, then rural communities worldwide would be happier, healthier, and wealthier -- and even less likely to be harassed by extremist groups that prey on isolated communities.

In truth, Ambassador Quinn has a point -- but he is only telling half of the story.  Roads are often good for people but can also be devastating for the environment.  The trick is to decide when roads are environmentally 'good' or 'bad'.

ALERT director Bill Laurance has written an opposing essay in National Geographic Online -- one that tries to bring a bit more balance to the issue of roads.  It's worth two minutes to read this rebuttal.

Laurance argues that roads should generally be avoided in wilderness areas, parks and other protected areas, and places with concentrations of endangered or locally endemic species.

Sadly, roads are expanding explosively today, and far too many roads are 'bad' -- opening a Pandora's Box of environmental problems, such as poaching, illegal deforestation and forest burning, illicit gold mining, and predatory land speculation.

We are living in the most dramatic era of road expansion in human history.  It is estimated that, by 2050, we will have another 25 million kilometers of roads -- enough to encircle the Earth more than 600 times.  Nearly every surviving wilderness area on Earth -- from the Amazon to Siberia, and New Guinea to the Congo Basin -- is under assault from roads. 

From an environmental perspective, we are blazing along a road to ruin

Let's hope that road enthusiasts like Ambassador Quinn start to get the message.  Roads are, at best, a double-edged sword. 

And far too often, the sharp edge of the sword is pointed at nature's throat.