Soil characteristics and leaf nutrients of healthy and declined Brant`s oak (Quercus brantii Lindl.)

Nowadays, the oak decline phenom in the Zagros region of Iran has converted into a serious crisis that needs more attention and research to provide forest managers with solutions. The aim of the study was to understand the soil quality and leaf nutrients of declined oak stands (Quercus btantii) in the Kohmareh Sorkhi region. To do so, soil samples were taken from the under of the healthy and declined trees’ crowns and then soil characteristics including moisture content, pH, electrical conductivity (EC), organic carbon, nitrogen, phosphorus, potassium, gypsum, calcium carbonate, calcium, and magnesium contents were measured and compared. Morover, NPK content was measured on taken leaves from each trees. The results indicated that soil moisture, EC, gypsum, lime, P, K, Ca, and Mg contents had significant differences. Although gypsum and lime contents were higher in the declined stands compared to the healthy ones, moisture content, EC, P, K, total Ca, and Mg content were higher in the healthy stands. The leaf nutrient statistical analysis demonstrated that the dieback individuals suffer phosphorus shortage, but N and K content were the same as the healthy ones. Given that some shortages were observed in the nutrient elements such as P, K, Ca, and Mg in soils under the crown of declined trees and P in their leaves, it seems that the nutrient shortage has an important role in the oak decline since the greatest shifts were recorded for which.