Deforestation led to demise of Nasca in Peru
November 2nd, 2009 by Jim JustThe Nasca people, best known for giant geoglyphs etched into the surface of a vast desert plain, once flourished in the valleys of south coastal Peru. About 500 AD their civilization collapsed into a bloody resource war and then vanished.
Photograph: Kevin Schafer/Corbis, published in the UK Guardian
What happened? Archaeologists from Cambridge University say the Nasca brought about their own demise by ruining the fragile ecosystem that supported them. Their study was published in the journal Latin American Antiquity.
Over the course of many generations, the Nasca cleared areas of forest for agriculture. The huarango tree, which once blanketed what is now desert, was gradually replaced by crops such as cotton and maize.
But the short-term agricultural gain came at a high price because the trees were the critical component of the ecosystem. Dr. Beresford-Jones explains what happened:
The huarango is a remarkable nitrogen-fixing tree and it was an important source of food, forage, timber and fuel for the local people. Furthermore, it is the ecological ‘keystone’ species in this desert zone, enhancing soil fertility and moisture, ameliorating desert extremes in the microclimate beneath its canopy and underpinning the floodplain with one of the deepest root systems of any tree known.
In time, gradual woodland clearance crossed an ecological threshold – sharply defined in such desert environments – exposing the landscape to the region’s extraordinary desert winds and the effects of El Niño floods.
In the absence of huarango cover, when El Niño did strike, the river down-cut into its floodplain, Nasca irrigation systems were damaged and the area became unworkable for agriculture. Infant mortality rose, while average adult life expectancy fell. The crops that had been cultivated by the Nasca for generations disappeared, and the area fell victim to a severe drought.
There are now no undisturbed ecosystems in the region, and what remains of the old-growth huarango forests is being destroyed in illegal charcoal-burning operations.