Relationship between Dead Trees with Soil Physico-chemical Properties and Earthworm in Mixed Broad-leaved Forest Stand (Case study: Sarcheshmeh Forest, Chaloos)

Dead trees protection, has a key role in structural and biogeochemical processes in forest ecosystems. Some aspects of dead tree dynamics have been carefully studied, but the kind and decay degree of dead trees and forest soil properties have not received enough attention. The aim of this research was to study the effect of a kind and decay degree of dead trees on soil mineral properties in the Sarcheshmeh Forest, Chaloos. For this purpose, the dead trees were investigated by strip transects with 10 m width and 80 m distance between transects. 71 dead trees were identified. In addition to determining kind of species, dead trees were categorized into four decay classes consists of a new dead tree, decay beginning, advanced decay, and perfect decay. The Soil sampling for estimating total nitrogen (%), available phosphorus (ppm), K (%), pH, soil moisture (%), carbon (%), C/N, and biomass of earthworm (g) was carried out in the closest position to the dead tree in 0–30 cm depth. Principle Component Analysis (PCA) method and analysis of variances were used to compare the relationship between dead trees and soil properties. The results showed that there was a strong relationship between carbon and C/N values with oak dead trees. Soil nutrients, pH and soil moisture (%) have displayed a significant relationship at the 5 percent probability level with alder and hornbeam dead trees. The fourth decay class had the most values of N (0.76%), P (15.53 ppm), and earthworm biomass (26.61 g), whereas there is no significant difference between first and secondary decay classes. The K (%), pH, and soil moisture (%) values were increased from first to fourth decay classes. Based on the findings current study on the key role of dead trees in forest soil richness, the dead trees should be protected during forestry operations in each forest ecosystem to sustain soil productivity.