Study on Accuracy of Assessment of the Canopy Cover Density in a Pure Persian Oak Stand, by Using the Method of Terrestrial Photography

In order to study the accuracy of assessment of the canopy cover density of a pure Persian oak stand with mixed coppice and standard forms using terrestrial digital photography, 16 circular sample plots with an area of 4.9 in a grid with sizes of 25 m by 25 m, over as forest stand with an area of 1 ha, with was used. The method of vertical sighting with Same as Cajanus tube was considered as the method of control to record either present or absent of canopy cover in 195 systematic sample points in each of sample plots. 9 vertically terrestrial digital photographs that contained of an image in the centre of the sample plots, 8 images in line with the bout main and sub- main geographic directions were taken. By calculation of the percentage of the canopy component of the forest stand using these methods, the results of the Kruscal–Wallis statistical test showed that there were not statistically significant differences between the different methods of estimation of the canopy cover component. In terms of the superiority of the bias indicator over the other methods, the method of 5 digital images in the main geographical directions, the method of 9 digital photographs and the method of 5 digital images in the four sub directions were ranked from 1 to 3, respectively. The different methods of terrestrial digital photography would underestimate the canopy cover component in comparing with control method.