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.
 

The blight of illegal gold mining

If you want a shock, take 30 seconds to watch this video--filmed from a airplane flying over the Peruvian Amazon.  The narration is in Spanish but it won't matter...

Gouging the earth for gold... illegal miner in Suriname (photo by William Laurance)

Gouging the earth for gold... illegal miner in Suriname (photo by William Laurance)

if this were just happening in Peru it'd be one thing, but 'blood gold' has turned into a global crisis.  Especially in developing nations, the combination of high gold prices and too many poor people is creating almost unstoppable pressures for miners to invade parks, wildernesses, and anywhere else that alluvial gold occurs.

Mining moonscape... illegal gold mining in Sumatra, Indonesia (photo by William Laurance)

Mining moonscape... illegal gold mining in Sumatra, Indonesia (photo by William Laurance)

Completely unregulated, the environmental impacts of illegal mining are many--destruction of riparian habitats, massive increases in river sediment loads, and toxic mercury pollution among them. 

And that's not to mention the human toll that the miners take on indigenous groups and rural communities trying to survive in areas ravaged by mining, when the fish are gone and the only source of drinking water is now tainted.

The take-home lesson: Too much of the gold we buy comes with a big, hidden price tag...