An investigation on relationship between morphometry of sand dunes on the establishment of Haloxylon aphyllum (A case study: Yazd Erg

Sand dune is one of the most important features of wind erosion developed in arid and severe arid regions. Generally the angel of leeward section (20-35°) is more that windward slope. Due to strategic position of Ashkezar, in yazd province, the project of combating sand dunes movement was conducted in 1983 through implanting of Haloxylon aphyllum by Yazd natural resources office. The main aim of this paper is to investigate the effect of dunes high and morphology on establishment of Haloxylon in the Ashkezar Erg. The morphology map of Erg was extracted through interpretation of aerial photos and Google Earth satellite images and field observation. Vegetation sampling were done through 48 transects (30×20m) to inventory of vegetation cover on the surface of different sand dunes type. In this study vegetation density, cover and vitality index of established trees were estimated. Results indicate a significant difference (P<1%) between lower one-third and upper two-third of windward dunes high. Moreover field observation revealed that no vegetation have being established on the crest and upper part of sand dunes which can be addressed to wind velocity on the crest of sand dunes. On the lee ward side of dunes, the Haloxylon could fix the lower one-third part. According to the results it should be mentioned that to increase the efficiency of sand dunes and decrease the irrigation and supplementary cost of fixing projects the morphology of sand dunes should be taken into account.