Do soil properties and ecophysiological responses of oak (Quercus brantii Lindl.) correlate with the rate of dieback?

Abstract

The physical and chemical properties of soil are not a determinant of oak decline. Under stress, trees keep their vital activities by changing their physiological performance. The phenomenon of oak decline has been reported widely in various regions in the world. Although, many studies have addressed this problem, further studies are required to accurately identify the influencing factors. In this regard, we measured and analyzed some physiochemical properties of soil and some ecophysiological attributes of oak trees in different classes of dieback in Zagros Forest. We also used the Standardized Precipitation Evapotranspiration Index (SPEI) to determine the occurrence of drought in the study site. The findings indicated that dead trees and trees with a high rate of dieback were mostly present in soils with heavy texture. Besides, a significant difference in malondialdehyde (MDA) was found in various dieback classes. Moreover, with increasing dieback, the content of Ca in the leaf increased and the N/P ratio decreased. In these conditions, oak trees change their absorption and consumption of required elements.