Analyses of coarse woody debris impacts on soil organic carbon variations in the Hyrcanian Caucasian oak (Quercus macranthera) forests

One of the concerns for the executive organizations to introduce an alternative plan of rest of the Hyrcanian forests is to make decision regarding the exit of coarse woody debris (CWD) volume from the Hyrcanian forests. The research was carried out in the permanent plot with 400 m2 based on the protocols of the comprehensive research plan enacted by Agricultural research Education and Extension organization in Iran. Within each plot beneath the CWDs over than height of 1.5 m and dimensions of 7.5 cm, the organic accumulations resulted from the decay trend were sampled. Besides, the soils mineral layer up to 10 cm depth were sampled after removing the organic accumulations, and were transported to the laboratory. The results of PCA (Principal Component Analysis) showed that beneath the CWDs including higher organic accumulations, amount of the organic carbon and the nutrients were lower in the substrate soil mineral layer. Furthermore, the results of Spearman test indicated that amounts of organic carbon and nutrients in the organic and substrate mineral layers were independent of each other (P > 0.05), and amounts of the organic carbon with Nitrogen were significantly correlated (P < 0.01). Also, the results of two-way PERMANOVA test indicated that interactions of form, species and decay of the CWDs in the study sites were not significantly effective on the organic carbon under the CWDs.