Study area
The study was carried out in 2658 ha of desertic arid area in the
Abougovair region (extended form 32° 13ʹ 17″ to 32° 16ʹ 56″ N and 47°
43ʹ 16″ to 47° 48ʹ 30″ E), located in Dasht-Abbas town, in southern part
of Ilam province, Iran (Fig. 1). In this region, sand dune (1018.6 ha),
poor rangeland (1307 ha), non-rain fed (182.9 ha), and rain-fed (149.6
ha) are the main land uses, and agriculture and animal husbandry are the
main occupations of the people. The mean annual precipitation, potential
evapotranspiration, and temperature were 210 mm, 3857.5 mm, and 26.2 °C,
respectively. The altitude in the studied area varied between 60 to 220
m above sea level, and the slope is less than 8%. The soil type in the
study area is Inceptisols, based on USA classification.
The desertification in this arid region is mainly due to climatic
conditions, improper extraction of groundwater, population growth,
degradation of pastures and rangeland, increase in the number of
livestock, and expansion of agricultural lands. To combat
desertification, with the approval of the Forests, Range and Watershed
Management Organization of Iran, it was decided to stabilize an area
(about 400 ha) of this region using excess petroleum materials (i.e.,
oil-mulch). Therefore, in 2018, 8.2 ton/ha oil-mulch was sprayed to
stabilize sand dunes and facilitate plant establishment.