Autecological study of Acantholimon olivieri (Jaub. & Spach) Boiss. in mountainous rangelands of Hamedan province, Iran

In this research, the autecology of žAcantholimon olivieri, a perennial-spiny-tragacanth shrub from Plumbaginaceae, was investigated in Hamedan province. First, its habitats were detected throughout the province. All of these habitats were located in mountainous regions. Three of these habitats (Malayer, Gonbad, Asadabad) were selected and four sites were chosen for each habitat. Then, the climatic features and soil characteristics of the habitats, the root system, phenology, reproduction, and the vegetation factors were assessed. The vegetation and soil factors were measured applying the systematic-randomized method. Six composition soil samples were collected at the base of the shrubs in each site and were analyzed at the laboratory. The average annual rainfall of the habitats was 315 mm, and the average annual temperature was 12 0C. This species endures temperatures between -230C and �. It appeared on soil with sandy clay texture, a pH of 8.03–8.31 and electrical conductivity of 0.44 mmoh.cm-1. A. olivieri has a 1.13 m direct and vertical root system penetrating as deep as 1.13 meters in the soil. The average canopy and frequency of žA. olivieri in each of the habitats were 15 and 38.4%, respectively. Also its density and reproduction were 2957 and 26 shrubs.ha-1. The vegetation growth stage, flowering, seed ripening and dormancy of žA. olivieri started in late April, mid-August, late September and late December, respectively. Since this species is not grazed and is highly resistant to undesirable environmental conditions, it can be used in conservative and management programs in mountainous regions.