Efficiency of LTS and LIS methods for wild pistachio (Pistacia atlantica Desf.) density estimates in Zagros forests, Iran

Density (i.e. number of trees per hectare) in a forest stand shows current status of the stand and its monitoring is important to assess the stand’s changes. On the other hand, application of distance methods is spread widely to estimate stand density, especially in woodlands. This research was aimed to apply and compare LTS and LIS methods, as important distance methods, to estimate wild pistachio density in Zagros forests, Iran. A 45 ha plot was selected in Wild Pistachio Research Forest in Fars province for this purpose. A pilot experiment showed that the effective length of transect was 167 meters in LTS method that was applied in 10 sampling points and the perpendicular distances of the wild pistachio trees less than 46 meters were measured in these transects. Also in LIS method, a preliminary inventory showed that the transects applied in LTS method was suitable for this method. The results showed that the density of wild pistachio trees was 21.1 with 95% Cl=16-26.2 and the mean density was not also different from the true density (19.4 trees ha-1) significantly. While density was 26 in LIS method with 95% Cl=18.7-33.3 and it was significantly different from the true density. Consequently, LTS method was more efficient for wild pistachio density estimate in the study area and it is suggested to assess this method in other parts of Zagros forests.