Scubaben/flickr The Nazca Lines Called The Dog

An article in the Telegraph says events induced by the Nazcas led to their demise around 500 A.D. These ancient Native Americans cleared huarango forests to make room for agriculture, eventually replacing the forests with cotton and maize plantations. The study, published in Latin American Antiquity, found the huarango kept moisture in the narrow plains and helped the soil remain fertile, thus keeping the Nazca’s narrow irrigation channels in place. Cambridge University’s Dr David Beresford-Jones explained why cutting down the native trees was so serious:

These were very particular forests. The huarango is a remarkable nitrogen-fixing tree and it was an important source of food, forage, timber and fuel for the local people. 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.

Explaining how human intervention changed the ecology, Beresford-Jones added:

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 Nino floods.

Beresford-Jones also pointed out that the study showed that Native American peoples did not always live in harmony with nature in pre-Columbian times, as popular perceptions had it.