Upper Colluvial Zone (UCZ)

This zone is located in the higher elevations, on exposed erosional surfaces of the Taraco Formation. Though it was originally said to exist from 3975-4100 m.a.s.l., my own elevation distribution places it as low as 3860 m.a..s.l. (Table 2.1). The zone is dissected by deep, steep-sided quebradas, normally running from south to north, as discussed above. The ground in these areas is extremely rocky, and the soils are thin. Nevertheless, they are used for agriculture, though less so than lower and less rocky areas (contra [Albarracín-Jordan and Mathews 1990]: 16). Principal crops seem to be cereals, including barley (Ordeum spp.), wheat (Triticum spp.), quinoa (Chenopodium quinoa), and cañawa (Chenopodium pallidicaule); the Andean tubers seem to fare less well here than at somewhat lower elevations. Vegetation is sparse, and consists mostly of brushy shrubs. These include khoa (Menta pulegiur, Satureja boliviana), añahuaya (Adesima spinossisima), khanlla (Tetraglochin cristatum) ([Albarracín-Jordan 1996a]: 11). Bunch grasses are also present in low densities.

Table 2.1: Sector count by micro-environmental zone and elevation

Elevation	Springs and Grass Zone	Lower Colluvial Zone	Upper Colluvial Zone
3800	95	140
3820	11	301
3840	1	135	5
3860		78	7
3880		10	23
3900		2	13
3920			1
3940
3960
3980			2
4000