Yahya Kooch
Dead tree is an important ecological factor for changes and heterogeneity creation of soil characters that attracts different livings. Due to investigation the decay degree effects of downed tree on soil characters and earthworms ecological groups, the Sardabrood forest of Chalous studied that is located in Mazandaran province, northern Iran. For this purpose, 306.2 ha areas considered at 700 - 1300 m altitude range and twenty seven downed trees of beech and hornbeam species were found. Decay degree of downed tree classified in four classes (DC1, DC2, DC3 and DC4). Whole of dead trees selected as the center of sample plots and mixed soil samples were taken from theirs besides and along at 0 -10, 10 - 20 and 20 - 30cm depth. Soil acidity, water content, total carbon, total nitrogen and carbon to nitrogen ratio measured in the laboratory. The earthworms were collected simultaneously with the soil sampling by hand sorting. The maximum of acidity and water content considered in DC4 of dead trees and significant differences were found. But, soil depth had no significant differences for these characters. Also, the most amounts of soil carbon and nitrogen found in DC4 of dead trees and upper layers of soil. DC1 of dead trees and soil lower depths devoted the maximum of carbon to nitrogen ratio. Principal component analysis (PCA) showed that the most assemblage of earthworms were around of dead trees with high decay degree (DC4). Number and biomass of earthworms group in dead trees positions indicating endogeics are due to creating significant statistical differences between beech and hornbeam downed trees.
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