Investigating the vertical distribution of soil characteristics under canopy Haloxylon appyllum in Yahya Abad, Sabzevar

Haloxylone is a common shrub for stabilization sand dune in Iran.The objective of this research were to investigate the effect of Haloxlylon on the physicochemical properties of soil and the possibility of fertile islands formation in Yahyaabad, Sabzevar. Firstly, based on field observations and vegetation inventory, two regions with good and moderate Haloxylon coverage were identifies and 4 and 5 sampling sites in the good and moderate coverage were selected, respectively. To examine soil morphological and physicochemical characteristics, in each site, two soil profiles under and between plants canopies (totally 18 soil profiles) were described and sampled from genetic horizons. The results showed that the amount of Pa, Nt, and SOC in fertile islands are considerably higher than between plants, especially in surface layers in good coverage regions. Coordinated changes of HCO3- and SOC indicating their close relationship. Because of high mobility of Na, K, and Cl- and HCO3- the amount of these ions and consequently EC and SAR have increased in all soil layers under canopies in comparison to between canopies . The composition of Haloxylone leaves indicated that decomposition of falling leaves is the main factor of increasing the mentioned characteristics. The low amount of Mg2 and Ca2 in leaves explained insignificant changes of these ions under canopies. Among the physical properties, only the saturation percentage (SP) has been increased in surface layer due to close relation of this parameter to SOC. The results of this study confirmed the formation of fertile island under Haloxylon which extended with less intensity to subsurface layers.