Why does the desert around Lima have so little natural vegetation?

The desert surrounding Lima experiences minimal natural vegetation primarily due to its extremely arid climate, where annual precipitation rarely exceeds 2 inches (50 mm). This severe dryness is caused by three main factors:1

• The Andes Mountains: The range acts as an orographic barrier, blocking rain-bearing winds from the Amazon Basin and creating a rain shadow effect.23
• Atmospheric Pressure: High-pressure air masses from the South Pacific create stable, subsiding air conditions that inhibit rainfall.23
• The Peru (Humboldt) Current: This cold ocean current flows northward along the coast, cooling the surface air and stabilizing the atmosphere, which prevents the formation of rain-producing clouds.234

While the region is generally barren, the lack of consistent moisture limits plant life to a few hardy shrubs and terrestrial bromeliads. Some areas receive enough humidity from garúa—a dense, persistent winter sea mist—to support lomas, a temporary growth of grasses and herbaceous species. More diverse vegetation is found only in the Andean foothills or along river valleys where water from the mountains is available.512