Variation in soil carbon stock and nutrient content in sand dunes after afforestation by Prosopis juliflora in the Khuzestan province (Iran)

Abstract

Prosopis juliflora is one of the suitable tree species used as vegetation cover for sand dunes fixation. The objectives of this study were to determine the effect of P. juliflora afforestation and its canopy coverage classes on soil carbon (C) stock and nutrient status in sand dunes after 22 years since afforestation. We hypothesized that increasing the canopy coverage would result in higher soil C stocks and nutrient content. We selected two 10-ha afforested sand dunes with 25-50% and more than 75% canopy coverage, respectively, and a 10-ha non-afforested dune (control). At each site, 15 soil samples were taken at two depths (0-5 cm and 5-50 cm). The results indicated a strong increase in the topsoil C stock (from 0.54 to 4.49 tC ha-1 in control and afforested sites, respectively), while a lower change in subsoil C stock was detected (3.0 and 4.6 tC ha-1 in control and afforested sites, respectively). Although, different canopy classes resulted in no significant differences in soil C stock, significant differences were observed for all the soil physico-chemical properties that were studied.