Introducing the improved Forest Canopy density (FCD) model for frequent assessment of Hyrcanian forest

Mapping of forest extent is a prerequisite to acquire quantitative and qualitative information about forests and to formulate management and conservation strategies. forest canopy density (FCD) model is one of the useful RS methods for forest mapping using satellite images. One of the most serious challenges in FCD model is the weakness in the calculation of canopy density in low density forests as well as plain forests. Due to the existence of chlorophyll in croplands, shrubs, pastures, etc., FCD model has difficulty to determinate the forests areas from the other mentioned land cover. Hence, this paper is focused on improving the performance of FCD model to overcome this limitation. This improvement yield by adding a new forest color composite index (FCCI) and removing non-forest vegetation using the average kernel and DEM regard to standard forest definition. In this study, in order to implement and evaluate the performance of the improved model, time series of Landsat images acquired from USGS Landsat standard level-2 products archive. In this study, Landsat time series images acquired from USGS Landsat standard level-2 products were used to estimate forest canopy density in Hyrcanian forests of northern Iran. The results indicated the higher accuracy of the proposed model. Moreover, overall accuracy and kappa index of the model were 10% and 24% superior to initial model, respectively. As a second objective, in order to implement and evaluate the performance of the improved model, canopy changes of the Hyrcanian forests were also examined. In general, the results of this study showed that the total area of Hyrcanian forest increased from 154,272 hectares from 1987 to 2017. Mazandaran, Gilan and Golestan provinces contributed 75,070, 47,615 and 31,567 hectares respectively. In addition, the results showed that the area of Hyrcanian forests decreased by 17,631 hectares between 2009 and 2017.