The Efficiency of the Aerial Photos and IKONOS Images in Estimating the Canopy Cover of Street Trees (A Case Study in Region 1 of Thehran)

Information about the structure of the urban forest such as the compoition of species and the density of canopy cover is prerequisite for planning, designing and managing of the urban vegetation on a local and regional scale. So in this syudy, different methods of inventory, including 100% inventory with 15 meters transect and aerial photos (with 1:8000 scale) and IKONOS images (with 1 meter spatial resolution) were compared in order to find the optimum and most appropriate method in estimating the canopy cover of street trees in one kilometer in Shahrivar 1386. In 100% inventory considered as the basis for comparing with other methods, the canopy cover of trees is estimated in every 15 meters transect. The results of paired t-tests analysis showed that there were not significant differences between the 100% inventory, aerial photos (df=38, t=0.709, and p=0.48) and IKONOS images (df=38, t=0.887, and p=0.38). The results of regression analysis also indicated that the aerial photos (R2=0.87), and IKONOS images (R2=0.62) were suitable for estimating the canopy cover of street trees. The expenses spent in 100% inventory for estimating the canopy cover of street trees were respectively 6.5 and 34 times greater than those spent in estimating that with the aerial photos and IKONOS images as the expenses spent in the aerial photos were also 5 times more than those in the IKONOS images. Therefore, based on the results of the study, we can suggest that the satellite images with high spatial resolution such as IKONOS and Quickbirds images with lower times and expenses can be used for estimating the total canopy cover of street trees, and the better management of them in metropolises and to be aware of changes in these valuable resources in short periods of time.