بومشناسی جنگلهای ایران (Aug 2023)
Estimation of Biomass and Its Reduction in Forests Affected by Decline in DadAbad Region, Lorestan Province
Abstract
Extended Abstract Introduction and Objective: The forests of Zagros, as the most extensive and at the same time as the most damaged forests of the country, have been affected by the extensive decline of oak trees in recent years, and in this sense, they are in a critical conditions. Decline of oak trees is described as a wide and complex phenomenon that causes a decrease in growth and physiological weakness followed by the attack of pathogenic agents. As sustainability of these forests is now facing a serious problem, proper management strategies are required to deal with the decline phenomenon, before these valuable ecosystems are completely destroyed. The implementation of such strategies necessitates collecting basic information, including map of the decline distribution and the extent of the lost biomass of trees as a result of decay. The purpose of this study is to estimate the amount of biomass on the above-ground in dead oak trees as a result of the decline of Zagros forests, which was carried out in the forests of Dadabad region of Lorestan province. Material and Methods: The present study was conducted in Dadabad forests located in the southwest of Khorramabad, Lorestan, Iran. To achieve this purpose, 40 dried trees were randomly selected and biometric parameters including diameter at knee height, diameter at breast height, as well as height and crown diameter were measured. Different parts of the tree were fragmented, dried, and weighed. Using regression analysis, the biomass of different parts was modeled against the independent variables of diameter at knee height, diameter at breast height, crown height, and diameter. Finally, at the area of 32 hectares of the forest stand, a 100% inventory was conducted, and different characteristics of all Iranian oak trees were measured. Results: The results of the research declared that strong relationships can be established to estimate the biomass of Iranian oak trees. The result of fitting linear and non-linear models to estimate the biomass of this tree species showed that if the average diameter of the tree crown was used as an independent variable, the more suitable model was the power model with an explanation coefficient of 0.857. Also, the validity results of the model or the value of RMSE% for the obtained equation was 9.082%. The total biomass in the study area was 389.994 tons, of which 39.54%, i.e. 154.226 tons, of the area's biomass was lost under decline phenomenon. Conclusion: The results indicated that in the comparison between linear and non-linear regression models, the best model for estimating the biomass of this species was the power model based on the average diameter of the crown with R2=0.857. In general, using the average diameter of the crown as an estimator variable for the Iranian oak species can suggest a better and more appropriate assessment of the above-ground biomass of these trees.
