Agricultural Settlement and Land Use in Mountains - Mountain Geography: Physical and Human Dimensions - page 553

taking a collective toll. Incursions from corporate and private logging and mining op-
erations also play a role. Table 11.1 summarizes the active shifting cultivation farming
regions.
Terraced Agriculture
A second and very different strategy used to cultivate tropical mountains is the elabor-
ate terracing of mountain slopes. While shifting cultivation tries to mimic the rainforest
and requires little or no other field preparation, terracing permanently removes the
tree cover and alters the slope gradation. Constructing terraces is common in most Old
World mountains, particularly in the tropics, but also in drier mountain areas in Europe
and the Middle East. They form distinctive and mesmerizing cultural landscapes that
vary greatly in their dimensions, distribution, purpose, and the methods and quality of
construction (Fig. 11.9).
Terracing requires tremendous community organization, as an extensive network
supports numerous landowners. It also requires a well-coordinated cooperative main-
tenance schedule. In the Andes, a person working alone needs 610 days to construct a
3-ha (7.4 acre) terrace (Treacy 1989). In eastern Bhutan, it takes 1,320 worker days to
construct a 1-ha (2.5 acre) terrace on the steep slopes of the eastern Himalaya (Clark
1986). Such statistics explain why farmers may own all or part of an individual terrace,
but they maintain them cooperatively. The steeper the slope, the higher the riser wall
between terraces, and the narrower the terrace surface. Many simply consist of shallow
corrugations along the contour, whereas others involve construction of elaborate stone
walls or soil bunds several meters high, carefully engineered to support level areas on
their treads. For example, on broad alluvial fans such as above Dali, China, the riser
walls between terraces average less than 0.5 m (2 ft) high, while on steep slopes in Ne-
pal, the walls often exceed 2 m (8 ft). They often cover entire slopes, creating a land-
scape of giant stairways (Fig. 11.10). Terraces are built to allow efficient irrigation, to
prevent erosion, and to create more usable level land. All these functions are served
to a certain extent. The Nepalese build two types of terraces, depending on rainfall
and slope. In the wetter and steeper hillsides of the Middle Mountains, where monsoon
rainfall is abundant and irrigation is unavailable, wide bari (rain-fed) terraces angle
slightly out from the mountain slope to allow the excess to run off. This strategy pro-
tects against slope failure and prevents waterlogging of the maize, millet, buckwheat,
and other crops. In contrast, khet terraces angle into the slopes. Farmers often add a
soil bund (small narrow ridge) to trap both rainfall and runoff in these drier zones (Ives
and Messerli 1989; Barrow 1999).