Habitat Types of Desert Dunes

Abstract

The wide ecological range of desert dunes should be divided into two climatic types. (1) Dunes of extreme deserts where mean annual precipitation is less than 50mm. There is insufficient water stored in such dunes to support perennial plants. Perennials growing on these sands (such as stands of Haloxylon persicum in the southern Negev or the Arava Valley) use water in the substrates below the sand. Annual plants may briefly cover such dunes in years of sufficient rainfall. Under these conditions, plant impact on dune morphology is mostly negligible. In these extreme desert areas, nonsandy soil types may support vegetation in the contracted pattern (i. e., plants restricted to dry water courses; mode contracte, Monod 1931; Danin 1983). (2) Dunes in deserts with more than 70–90 mm mean annual rainfall do support perennial plants, and these form and modify the dunes. An attempt is made, in Section 8.3, to delimit the boundary between extreme and nonextreme desert areas, using the ecomorphological traits of plants.