Evaluation of different plot shape, size, and number for sampling in middle Taleghan rangelands

During recent decades، many rangelands have suffered degradation. To preserve these valuable resources، monitoring and evaluation is important. A proper assessment requires a precise sampling of the study area. In this study، different methods of sampling in terms of accuracy and time were analyzed in three sites in Taleghan rangelands. The optimum number of plots were investigated by evaluating different equations and determined the ideal plot shape and size according to the percentage cover of dominant species. Our data showed that the formula is the most appropriate method for determination of suitable plot numbers in estimation of canopy cover in terms of accuracy and saving time. According to this formula، use of 40 plots for Thymus kotschyanus، 30 plots for Astragalus microcephalus، and 40 plot for Bromus tomentellus give the best results for canopy cover estimation. The most appropriate plot shape and size were determined quadrate (2 × 2 m2) for T. kotschyanus and A. microcephalus and quadrate (1 × 1 m2) for B. tomentellus.