Investigating the effect of dead trees on food cycle of the forest ecosystem in Chelir district, Kheiroud forest, Noshahr

Dead trees are considered as valuable nutritional resources in forests. By being a part of food cycles, providing nutritional materials, and keeping moisture, they prepare a desirable environment for seed germination and seedling growth. This study was carried out in Chelir district in Kheiroud forest — one of the four districts under the administration of the Department of the Natural Resources of the University of Tehran — for investigating the effect of dead trees on forest soil. To explore and compare tN, tC, pH, and C/N ratios at two different layers, i.e. the humus and the mineral (in 10 cm depth below humus) layers, samples were gathered in 12 replications from dead trees (with 4 decay degree) and the forest soil (without dead trees) as the witness group. The aforementioned factors were measured and their C/N ratio was estimated under the laboratory condition. The results of the T-test indicated that the tN of the humus layer in dead trees was significantly different from that of the witness group at P<0.05 and the tC, pH, and C/N of the humus layer at P<0.01. There was also a significant difference between tN, tC, and C/N of the mineral layer at P<0.01, but no significant difference was discerned in the pH of these layers. In addition, a review of the paired-group test showed that there was a significant difference between dead tree and forest treatments regarding tC. However, there was no significant difference regarding tN between the two treatments.