DESERT AND XERIC SHRUBLAND
Present in 6 of 8 biogeographical realms (Nearctic, Neotropic, Afrotropic, Palearctic, Indo-Malay and Australasia.) Outstanding ecoregions belonging to this biome are the Namib-Karoo deserts of southwestern Africa, the Chihuahuan and Sonoran Deserts, and the Carnarvon Xeric Scrub of western Australia. The Deserts and Xeric Shrublands biome is composed of 101 ecoregions.
Evaporation exceeds rainfall, usually less than 10 inches (250mm) per year. The temperature variability is very diverse with some areas remaining hot all year long and others becoming frozen and receiving snow in winter. Daily temperature variability is a characteristic in most deserts since there is no cloud cover to provide insulation. During the day the temperature and evapotranspiration is high and during the night the temperature drops allowing most of its fauna to go out of their shelters and look for food. Flora and fauna species are adapted to low water availability and show remarkable evolutionary adaptations to minimize water loss among many other strategies. Some arid areas in the planet have been overgrazed in the past, including the Middle East, Southwest US, Northern Mexico, China and Mongolia. Some areas are still poorly managed by ranchers and herders. Since goats can survive with poor diets and low water supply, they are abundant in arid areas with scarce resources. This contributes even further to the depletion of the biomass and the consequent erosion of the soil.
There is a large diversity of forms and types of vegetation, including woody stemmed shrubs, succulent tissues, seasonal herbs, and many others. The Chihuahuan Desert and Central Mexican Deserts are the richest Neotropical deserts and hold the most diverse desert for cacti. Deserts are very rich in flora types and reptiles. In some regions, the number of endemics is very high.
KEY DESIGN CONSIDERATIONS
Protect soil from water and wind erosion
Prepare for and allow flash flood events
Manage grazing intensity to avoid overgrazing and depletion of vegetal cover
Protect from prevailing winds at night, which are the primary cause of heat loss
Leverage the strong sun radiation during the day with mineral mass to radiate heat during the night to the interior
Promote water infiltration and rain water harvest