Investigating the accuracy and precision of sector sampling in juniper forests of Amin Abad, Firoozkooh

In this research, with the aim of investigating the capability of the sector sampling method in juniper forests and comparing it with the fixed area plot (FAP) method, a 12.5 hectare district was first taken continuously and point map of the trees was prepared. Seven parts were identified based on land physiography (crest and valley). For the sector sampling method, four sectors of 45 degrees were determined systematically and density was calculated. A network of circular plots in a 50×50 m grid was also specified and the density for each district was calculated. As actual density was determined in the whole forest, the accuracy and precision of estimates were calculated and compared. Estimates of the density were compared together using paired-samples t-tests and with actual data using one-sample t-test. The results showed that there was no significant difference between methods and with actual values. The sampling error was lower in FAP method, but sector sampling was obviously superior in accuracy. The root mean square error (NRMSE) of the estimates in FAP method was more than the sector sampling method, but the variance of the error values in the different parts of the region was less than the sector method, which indicates a more consistent sampling method.