Encyclopedia of the Incas

Chile of any plant life. The physical geography on the east side of the eastern
cordillera is completely different. There, moist air from the Amazon rising along
the mountain front releases high amounts of rain that supports a low but dense
forest with tree ferns and epiphytes. Away from influences emanating from the
east or the west, highland precipitation is heavily seasonal with frequent
thunderstorms from November to April. Clear skies and cold nights dominate the
period from May to October.
Central Andean ecology is exceptionally diverse. Referring here only to Peru
and the standard classification of the so-called Javier Pulgar Vidal model, 84
possible ecological distinctions can be collapsed into eight zones. Two of them
are at low elevations, the dry coast (chala) and the forested plains (omagua) of
the Amazon Basin to the east. From east to west, six are arranged attitudinally,
beginning with the rupa rupa (high jungle), yunga (semitropical), quechua
(temperate), suni (cold temperate), puna (microthermal), and janca (perennial
snow). How the Incas characterized their diverse ecology cannot be known for
certain, but the practice of moving colonists to similar environments from which
they came suggests a nuanced view of their multilayered habitat.
Extreme environmental heterogeneity and an array of domesticated plants as
well as some animals (see Animals, Domesticated; Foodstuffs, Domesticated)
gave rise to certain practices that survived the Spanish invasion. In one form of
vertical land use, farmers grew crops and kept llamas and alpacas at different
elevations to reduce subsistence risk. Alternatively, different social groups, such
as puna herders and valley agriculturalists, set up an exchange system based on
resource complementarity. The great staple of the high Andes above 3,300
meters (10,827 feet) has been the potato, a crop that falls into several different
species and many cultivars. In the southern half of the Central Andes, Andean
people learned to preserve potatoes in the form of chuño by exposing them to
daytime sun and nightly freezes that broke down the cell walls of the tubers
thereby extracting the moisture. Camelid meat was also salted and dried.
Dehydrated food was storable and light in weight, which facilitated the food
needs of the Inca armies. It is perhaps significant that Inca expansion began in
southern highland Peru where, unlike in northern Peru, the climate permitted the
manufacture of chuño.
Maize became a staple in temperate Andean valleys hundreds of years before
the Incas arose. By fertilizing and irrigating, the Inca achieved maize surpluses.
By constructing stone-faced terraces and irrigation canals, they created more
arable land, much of it devoted to maize. Other indigenous adaptations assured