Efficiency of Cokriging Method to Map the Biometric Characteristics of Wild Pistachio (Pistacia atlantica Desf.) Woodlands in Fars Province

The aim of this study was to assess the efficiency of cokriging method in comparing to kriging to map biophysical properties of wild pistachio trees in Zagros forests. A 45 ha stand, covered with wild pistachio trees was chosen in FiroozAbad wild pistachio research site in Fars province. 87 circular plates with 800 m2 area were selected based on a 72 × 72 m2 grid. Biophysical properties (height, diameter at breast height, trees per ha, and canopy cover percent) of all wild pistachio trees were measured in each plot. Kriging and cokriging methods were then used to map each biophysical property. The results showed that mean error and root mean squared error of height, diameter at breast height, and trees per ha of cokriging method were less than kriging method. The regression coefficients of height, diameter at breast height, and trees per ha of cokriging method were also greater than the kriging method that showed the efficiency of the cokriging method in the improvement of estimation of trees’ biophysical properties. The amount of root mean squared error and regression coefficient were slightly better for canopy cover percent in kriging, though, they were not significant. In general, it was concluded that the maps of biophysical properties can be obtained with suitable accuracy and precision using Cokriging method.