Vegetation and Soil Properties of a Sandy Desert Affected by Shrub (Haloxylon aphyllum) Plantation and Oil Mulching

Planting shrub seedlings under oil mulches has frequently been used for stabilizing mobile sands in Iran over the last three decades. Sandy desert of Samad Abad, Sarakhs, northeast Iran, has been fixed by cultivating seedling of Haloxylon aphyllum under oil mulches. This study was designed to investigate the effects of the sand fixation project on soil and vegetation properties. Vegetation samples were taken in a randomized-systematic method from representative areas of the rehabilitated and control sites. At each site, nine transects, 50 meters long, were established. Canopy cover and density of two dominant shrub species (Astragalus squarrosus and Convolvolus hamadae) as well as the total canopy cover of understory plants were measured, along the line transects. In each area, 220 individuals of the two shrub species mentioned above were selected and their total and living aerial foliage volumes were measured. Moreover, in each area, four soil samples were taken from 0-20 and 20-80 cm depths. The percentage of organic matter was measured in soil samples. Data analysis was implemented using independent T-test. According to the results, oil mulch and Haloxylon plantation caused a significant reduction in the percentage of total canopy cover of A. squarrosus and density of A. squarrosus and C. hamadae but these practices increased the living aerial foliage volume of A. squarrosus and C. hamadae.