Efficiency Investigation of Dot Grid Method in Estimating the Canopy Closure Percent in Forests by UltraCam-D Aerial Imagery and GIS

Considering the canopy closure as one of the main biometric parameters in forest management، it is important to find a suitable method to estimate it. Comparing to field measurements، studying this characteristic on the remotely sensed data is more precise and accurate because of its view from top. For this purpose، dot grid is among the most applicable methods applied on remotely sensed data. It was aimed to evaluate the accuracy and precision of this method on UltraCam-D aerial imagery. A 30 ha study - area was selected in Zagros forests in Kohgilouye BoyerAhmad province and it was fully callipered. Afterwards، different dot grids were obtained based on sampling error percents (5 to 20) and applied in GIS. The statistical comparison of the results showed that changing the number of points in the dot grids did not affect the accuracy of them and the results of all grids (except 9 and 14%) did not show statistical difference with the ground truth، although their precision increased by increasing the number of points. Generally، it can be concluded that dot grid has the efficiency of estimating the canopy closure percent but there is no logical relation between the precision and accuracy of it.