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Northern forests of Iran are among the most important plant communities in Iran due to their dynamic and diverse vegetation composition and fertile soils. There is little information about carbon stocks of these forests. In the present study, above- and belowground carbon stocks of trees, litter, herbs and soil organic carbon stock at three selected sites of these forests were calculated using random plots and non-destructive sampling. The FAO method was used for carbon estimation of trees and Walkley-Black method was used for soil carbon stock and carbon coefficient was estimated directly. The results showed that both the tree carbon stocks and soil carbon stocks increased from east to west with increasing altitude, showing significant differences. The results also indicate that these forests have a high carbon sequestration potential as a green belt across the northern slopes of the Alborz Mountains, when the contribution of the aboveground section was greater than that  of the belowground section (soil and roots) at all sites.

Introduction: People with stutter, like other people, are prone to suffering from fears, stress, anxiety and anxiety. Aim:The purpose of this study was to compare cognitive flexibility, cognitive avoidance and mood in male students with and without stuttering in high school language in Tehran. Method:The method of this research is comparative causative research. The statistical population of this study was all male high school students in Tehran during the academic year of 2017-18. Out of the education districts, District 18 was randomly selected from among all schools in the educational area, a sample of 30 male students with stuttering disorder was selected through stratified sampling and 30 students without stuttering by cluster sampling as sample size. In order to collect the research data, Dennis and Vander Wall Cognitive Flexibility Inventory, Sexton and Dugas Cognitive Avoidance Questionnaire, Toronto mood nougat and Riley Stutter severity were used. Results:The results of the analysis of the research data showed that the mean scores of stuttering students in comparison with normal students in cognitive flexibility were lower, but in cognitive avoidance and alexithymia were upper (p<0.05). Conclusion:The results of this study showed that people with stuttering disorder are weaker in cognitive flexibility variables than in their normal students, and in cognitive avoidance and alexithymia compared to normal students.

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