Comparison of accuracy assessment of canopy cover density using a device similar to Cajanus tube and line intersect sampling in a Persian oak stand

The accuracy assessment of canopy cover density in a Persian oak (Quercus brantiiLindl) stand, using vertical sighting from terrestrial points toward canopy of treesto determine the presence or absence of canopy cover in grids with 195, 102, 49 and 23 points with a similarly made device of Cajanus tube were compared with together and with a line intersect sampling method. For this reason, in 0.49 ha sample plots, grids with mentioned number of points were laid out, and the method of 195 points was considered as control. Because of the nature of the data, Non-parametric Kruskal–Wallis statistical test was used to compare the ranked averages of methods. Moreover, accuracy values including RMSE (%) and Bias (%) were calculated for each of the methods. According to the results, there were no statistically significant differences between the used methods to estimate canopy cover. The least amount of Bias was related to grid with 102 points, line intersect sampling method, grid with 49 points and finally grid with 23 points, respectively.