What characteristic defines a desert ecosystem?

A desert ecosystem is primarily defined by its very hot temperatures and minimal water availability. Deserts are regions that receive less than 250 millimeters (10 inches) of rainfall per year, resulting in dry conditions. This lack of moisture creates a harsh environment where organisms must adapt to survive, often leading to specialized physiological or behavioral traits.

The extreme temperatures in desert ecosystems can cause rapid evaporation of water, further emphasizing the scarcity of this vital resource. Plants and animals in deserts have evolved various adaptations; for example, many cacti store water in their tissues, and animals may be nocturnal to avoid daytime heat. This fundamental characteristic of minimal water and extreme heat distinctly sets desert ecosystems apart from other types of ecosystems, where water is more plentiful and temperatures are more moderate.