The role of rainfall and light interception by litter on maintenance of surface soil water content in an arid rangeland (Khabr National Park, southeast of Iran)

Abstract The impact of rainfall and light interception by litter on maintenance of surface soil water content is determined in an arid rangeland in Khabr National Park in south-east of Iran. Litter weight sampling is done by 90 square plots, each 1 m2, that are randomly placed within site. After determining the intensity of a typical storm of the region (20 mm/h), the rainfall duration required to saturate the litter from dry-weight to constant-weight is determined from the litter wetting curve. To plot the wetting curve, an outdoor rainfall simulator is used to wet the litter. Then drying curve of litter moisture content is determined from obtained field data with four replications. For measuring soil water content, three treatments are tested i.e. bare soil, soil with wetted litter and soil with dry litter. Average of the measured interception loss of four samples was 0.64% of this specific simulated rainfall (5.2 mm). This study clearly showed that rangeland litter decrease evaporation of the soil water content and light interception by litter have more important role in decreasing evaporation from the soil water content than the rainfall interception by litter.