Plants in Deserts

Introduction

Desert is the biome classification for terrestrial regions of Earth that are climatically arid and have low vegetation cover. Additionally, the climate of such regions is often highly variable across seasons and years. While there is no single index that is used universally to define deserts, a simple one, proposed by Miegs (1953), is based only on precipitation, whereby extremely arid regions experience at least 12 months without rainfall, arid regions receive <250 mm rainfall annually, and semiarid regions receive 250–500 mm rainfall annually (Fig. 1). Boundaries based on this index do a good job delimiting deserts across the globe and correspond closely to boundaries used in other classification systems (e.g., Ezcurra 2006). But aridity is not simply based on the amount of water derived from precipitation; it also depends on the loss of that water, which affects its availability for plant productivity. A more inclusive definition of aridity comes from the comparison of...