The Andean cordillera is made up of many interwoven mountain ranges, which include high intermontane plateaus, basins, and valleys. The Northern Andes contains several broad ecosystems falling into four altitudinal belts. Its northern subregion is distinguished from the rest of the region by higher relative humidity and greater climatic symmetry between the eastern and western flanks of the range. The Central Andes are characterized by a succession of agricultural zones with varied climatic conditions along the mountains’ flanks and by large, high-altitude plateaus, variously called puna or altiplano, which are not present in the Northern Andes. The soil fertility of the northern altiplano is generally good. The western Central Andean ranges are relatively arid with desert-like soils, whereas the eastern ranges are more humid and have more diverse soils. The eastern slopes of the Central Andes in many ways are similar to the wet forests of the Northern Andes. Unlike the Northern Andes, however, these slopes have a dry season.

Extreme topography and climate make regional weather projections in the Andean cordillera difficult. For example, while air temperature generally decreases with increasing altitude, variability of mountain topography can produce much lower than expected air temperatures. Vegetation can also be unpredictable, although certain general patterns are discernible. At the regional or macroscale level, vegetation patterns in the Northern and Central Andes tend to reflect climatic zones determined by latitude and altitude. At the local or mesoscale level, however, this correspondence becomes less precise, as local variations in soil type, slope, drainage, climate, and human intervention come into play.

1. Based on the passage information, which of the following characterizes the northern part of the Central Andes’ high-altitude plateaus?

(A) high relative humidity
(B) fertile soil
(C) a succession of agricultural zones
(D) extremes in air temperature
(E) an arid climate


2. Based only upon the information in the passage, which of the following is a characteristic of the Central Andean cordillera that clearly distinguishes it from the Northern Andean cordillera?

(A) an arid climate
(B) a sparse human population
(C) wet forests
(D) a humid climate
(E) a dry season


3. Which of the following statements about vegetation patterns in the Andean cordillera is most strongly supported by the passage?

(A) Local vegetation patterns are determined by the same factors as regional vegetation patterns.
(B) Vegetation patterns vary more widely at the macroscale level than at the mesoscale level.
(C) Vegetation patterns are affected by more factors at the mesoscale level than at the local level.
(D) Some factors affecting vegetation patterns have only a local impact, whereas others have a broader impact.
(E) Human intervention has a greater effect than either altitude or latitude upon vegetation patterns.