The Appropriate Sampling Method for Estimating Density and Crown Canopy of Declined Oak Stands in Dinarkooh Protected Forest, Abdanan, Ilam

Oak decline as one of the most important environmental problems of Zagros forests, requires proper management to decrease trees dieback and mitigate its effects. This study aimed to find the best sampling method for estimating density and crown canopy of declined oak trees in Zagros Forests. All declined trees in an area of 100 ha of Dinarkooh protected forest were surveyed and trees density, geographical coordinates and their canopy covers were measured and recorded. Then digital map of all trees were made and in order to assess alternative sampling methods with a constant sampling intesity 3% three alternative adaptive cluster, systematic random and random sampling were mapped using 30 sampling 10 Ar plots and the above mentioned data on trees were measured on the map.Results of accuracy criterion, showed superiority of adaptive cluster sampling method to the other methods, for estimating the density and canopy cover of declined trees (5 and 4.76% error of estimate for density and crown canopy respectively). Since adaptive cluster sampling method is designed for sampling of the populations with clump distribution it can be concluded that declined oak trees follow cluster distribution and this sampling method can be recommended as a proper method for estimating declined oak trees in Zagros forest.