Effect of grazing intensity on soil and vegetation characteristics using Principal components Analysis

Different grazing intensities change the chemical and physical properties of soil and plant composition of rangelands. Accordingly, effect of livestock grazing intensities on soil and vegetation characteristics were investigated in the southeastern of Hashtgerd using Principal Component Analysis. Principal Component Analysis is a statistical method for defining new variables based on a linear combination of original variables. Three 5-ha areas were selected in the study area under treatments of no, moderate, high and continuous grazing intensities. Afterward, vegetation and important physical and chemical soil characteristics including moisture, specific gravity, soil porosity, infiltration, mechanical resistance, nitrogen, phosphor, potassium, pH, EC, soil texture and organic matter were measured in three grazing treatments for two years (2004 and 2005). According to the results, increase of grazing intensity increased forbs while grasses and shrubs decreased. Among soil properities, soil porosity and Mechanical resistance decreasid and pH, EC and K had the highest relationship with grazing intensity.