Exploring Desert Ecosystems

• Deserts are ecosystems defined by the interactions between organisms, the climate, and other non-living influences.
• Deserts are large, extremely dry areas with sparse vegetation, supporting distinctive plants and animals adapted to harsh environments.
• The dry conditions in deserts promote the concentration of minerals like gypsum, borates, nitrates, and potassium as water evaporates.
• Desert regions hold 75% of the world's known oil reserves.
• Students should be able to explain organism adaptations, characterize desert ecosystems, and illustrate structural adaptations of desert organisms.

Characteristics of Deserts

• Deserts are arid regions associated with warm temperatures but cold deserts exist.
• Desert surfaces are covered by sand, rock, snow, or ice, with sparse plant cover.
• Desert ecosystems cover approximately 25-30% of the Earth's land.
• High daytime temperatures and persistent winds accelerate water evaporation and transpiration.
• High evapotranspiration and low rainfall result in sparse perennial vegetation of widely spaced shrubs.
• Deserts are found in bands near 30° north and south latitude or in continental interiors, such as the Gobi Desert.
• Precipitation is low and variable, generally less than 30cm per year.
• Temperature varies seasonally and daily; hot deserts can exceed 50°C, while cold deserts may fall below -30°C.
• Deserts are dominated by low, scattered vegetation with a high proportion of bare ground.

Desert Flora and Fauna

• Desert plants include succulents (cacti, euphorbs), deeply rooted shrubs, and herbs that grow during moist periods.
• Desert plants have adaptations such as heat and desiccation tolerance, water storage, and chemical defenses.
• C4 or CAM photosynthesis is common among desert plants.
• Common desert animals include snakes, lizards, scorpions, ants, beetles, migratory birds, and seed-eating rodents.
• Many desert species are nocturnal and conserve water, with some obtaining water from breaking down carbohydrates in seeds.

Additional Facts

• Deserts receive less than 10 inches of rain per year and can be either hot or cold.
• Hot deserts have extremely hot days and cold nights.