effect of environmental and management factors on atriplex freshness and growth (case study: hossein abad hapeshloo, shahriyar, iran).

some of arid regions problems of iran are saline and sodic soils. in improvement and reclamation of iranian arid rangelands, some foreign species of atriplex had been imported and adapted for many years ago. the most adapted species was atriplex canescens. at the present research, some environmental factors, vegetative characteristics (na, ca, mg and k), soil properties (moisture, ec, ph, solute na and k, hard pan, caco3, caso4, etc), topography, climate (rainfall, temperature, frost) and management characteristics (pruning, enclosure, grazing, irrigation) were studied on atriplex canescens in two sites in hossein abad-e-hapeshloo of shahriyar, tehran province, iran. at first, field survey was done and proper sampling method was selected. based on distance between and within furrows, one hectare reference area was selected for each of low and high freshness sites, respectively. a random-systematic sampling method was used for vegetation and soil characteristics, along three transects with a length of 100 m vertical to furrows, nine plots were established. along each transect, three profiles were dug and samples were taken from two depths (0-30 cm and >30 cm). the wet and dried soil samples were weighted and soil moisture was estimated. then, some physical and chemical soil properties were evaluated. results of soil analysis showed significant diffrences between two sites for ph in lower depth, ec in the higher depth , caco3 and sand in the both depth, silt in the lower depth and clay in the higher depth. the amount of ec , esp, caco3 , clay and na were increased in lower depth of soil, in contrast, for silt, sand and k, the higher values were obtained in the above layer. for others yraits there was no significant difference between two sites. the mean of vegetation characteristics were more in high freshness site. it was concluded that physical (soil texture) and chemical soil parameters (lime, ph and others) had significant effect on shrub freshness. moreover, it was likely that management parameters including grazing, irrigation and environmental parameters including topography and water logging had important roles in improper growth of atriplex shrubs.