The relationship between Iranian oak decline (Quercus brantii Lindl.) and some properties of soil and determining the ecophysiological responses of this

To study the relationship between some physico-chemical properties of soil and ecophysiological properties of oak trees on dieback, Meleshabanan area in Lorestan Province was selected. Using the geographic information system (GIS), the landform map of study area was prepared. In this forest, 30 square sample plots with 2500 m2 area, in a random systematic grid (200*200) were selected. The percent dieback was measured and recorded. In each sample plot, soil and leaves of oak trees were sampled. Some soil properties such as texture, electrical conductivity, acidity, bulk density, porosity, organic carbon, organic matter, and concentrations of calcium, magnesium, nitrogen, phosphorus, potassium, and sodium were measured. Also peroxidase, catalase, and ascorbate peroxidase enzymes, MDA, proline, chlorophyll a, b, carotenoid pigment, and concentrations of calcium, magnesium, nitrogen, phosphorus, potassium, and sodium in leaves were measured. The results showed that there was a significant difference in clay, sand, soil texture, Ca content, N/P ratio, and, MDA concentration between different dieback classes. Leaf Ca concentration with increasing dieback increased, while MDA first increased and then decreased. Also, the results of canonical correspondence analysis (CCA) showed that the frequency of trees in high dieback classes and the number of dead trees were directly related to bulk density and %clay and inversely related to %porosity, %sand, Mg, K, and N content.