Huangaro Trees are Peru Desert Keystone Species
Collapse of Nazca Civilization Linked to Deforestation for Crops
Nov 11, 2009
When the term keystone species is mentioned, most people think of mammals, and often specifically of top level predators.
But in the Peruvian desert, the loss of a species of tree, the huangaro (Prosopis pallida), resulted in the collapse of an ecosystem and a civilization. Reforestation with huangaro trees is helping the region to recover.
The Role of the Huanagaro in the Collapse of the Nazca Civilization
1,500 years ago the Nazca disappeared from Peru. It was long thought that flooding during a severe El Niño event led to their downfall. New research indicates that the Nazca had been clearing huarango trees to make way for agricultural development. The removal of huarango trees, a keystone species which stabilized the land and provided food, likely resulted in increasingly severe flood impacts during the El Niño events.
Archeological Find Indicates the Importance of This Keystone Species
Using pollen dug from deep in the soil of the Ica Valley in Peru, an archeological team from University of Cambridge in the UK was able to piece together a picture of the changes that took place which resulted in the disappearance of the Nazca people.
As more and more huangaro trees were removed to make way for corn and other cultivated crops, the soil became less stable. When El Niño floods occurred the crops were washed away. The next thing the archeologists found was an increase in weed pollen, mostly of salt adapted plants which can live in the Peruvian desert as it exists in the area today.
Restoration of Huarango Forests Helps Local People and Wildlife
Today, efforts are underway to return the huarango tree to Peru’s Ica Valley. The huarango develops very deep roots, allowing them to tap into aquifers 50 or more meters underground. In an area where there is only seasonal water flow from the Andes and no significant rainfall, the huarango tree thrives.
The trees were once a source of food for the local people, one that was available even in drought years. Huarango fruit is highly nutritious and the trees also provide wood for building and cooking. Their nitrogen fixing ability helps improve the soil for other crops as well.
As with the Maya nut tree in Central America, restoration of huangaro trees will provide food and other necessities, not only for the people of the area, but the wildlife as well. Endangered species including panther, guanaco and a variety of birds are returning to the wildlife corridors of huarango trees being planted around some of the Ica Valley farms. The restoration process, which is being done in partnership with the Royal Botanical Gardens at Kew, is the first of its kind in fragile desert habitat. If it is successful, it will provide a model for similar projects in other parts of the world where deforestation is causing severe environmental damage.
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