investigation of the fire effect on some edaphic factors in plain ecosystem (case study: winter rangelands of behshahr)

the fire as one of the ecological factor has positive or negative effects on ecosystems components. therefore, this study was evaluated the effect of fire on some soil physico-chemical properties in winter rangelands of behshahr. so that two burned sites were selected in rangelands and changed rangelands to wheat and barley with two control areas (unburned) in each of them. the soil sampling was done by three transects (100m) with ten sample points in random-systematic method (total 30 samples in each area). soil samples were taken in 0-15cm depth. the soil physico-chemical properties such as bulk density, moisture, texture, potassium, phosphorus, nitrogen, calcium carbonate, organic carbon, acidity and electrical conductivity were measured in lab. finally, the data was analyzed by paired t-test in spss19 software. the results showed that the fire in rangelands had significant effect on moisture (p≤ 0.01) and organic carbon (p≤ 0.05) reduction but p (p≤ 0.01), k, ec and ph (p≤ 0.05) have been increased. while k had significant increase (p≤ 0.05) and moisture had reduction (p≤ 0.01) in changed rangelands. generally the results showed that soil chemical characteristics in natural ecosystems had clear and more specific reaction against the fire in comparison to changed rangelands. also according to the results, it is necessary to manage intensity and time of fire to control the fire next effects.