Factors influencing the relative recovery rate of dunes fixed under different sand-fixing measures in southwest Iran

Abstract

The present study was conducted to determine the responses of sand dunes, using different restorative measures on different decadal time-scales in desert lands of southwest Iran. The study was carried out using a factorial experiment with a completely randomized design which was replicated three times. Factors consisted of restoration measures (PM-BF: petroleum mulching-biological fixation, PM: petroleum mulching, IP-BF: irrigation practices-biological fixation), history of fixation (<5, 5–10, 10–20, 30–40, and 40–50 years), and depths (<3, 3–10, and 10–40 cm). The physical, mechanical, and chemical properties of sand dunes were measured. Furthermore, vegetation cover parameters included Shannon’s diversity index, and spectral indices were determined. The relative recovery rate (Rr) of sand dune properties for different decades after fixing sand dunes was investigated. The results of this research disclosed that all three measures of PM, IP-BF, and PM-BF led to the improvement of sand dune properties. However, no significant differences were noticed between the effects of different measures of fixing sand dunes on the properties of the sand dune ecosystem. The Rr coefficient of parameters such as Shannon’s diversity index (3.58), organic matter (4.08), clay (2.8), silt (1.78), electrical conductivity (5.78), sodium absorption ratio (5.38), cation exchangeable capacity (1.48), penetration resistance (11.14), and cohesion (4.12) increased over the time period of 30–40 years compared to the initial years of sand dune stabilization (<5 years). The Rr of sand dune properties decreased from the east to west of sand dunes in this study due to a drop in precipitation as well as mismanagement, including deforestation and overgrazing. Therefore, socioeconomic factors play an important role in the recovery of ecosystems in this region.