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Showing 3 results for hosseini

Ahmad hosseini,
Volume 1, Issue 1 (9-2014)
Abstract

Crown dieback is of the phenomena that mainly has affected Persian oak trees. In order to assess the crown dieback of trees in forest stands of oak trees and its relationship with the individual trees, tree origin and size of tree canopy, Shalam forested area in the northern half of the Ilam province was selected. After dividing the study area into topographic homogeneous units, the biggest unit was selected for assessing the research objectives. Within the selected unit, 6 parallel transects were laid and about relatively 60 healthy and dieback trees were recorded. Then crown dieback, position of tree in stand, origination of trees, minimum and maximum crown diameter and crown height were measured. Data analysis was performed by analysis of variance and linear regression. Results showed that individual trees had healthier crown than the rest of the trees. Standard trees showed less crown dieback than the coppice trees. Effect of crown size on crown dieback depended on the location of trees as single or group and tree form. Totally it can be concluded that oak trees would give different responses to drought in terms of their individual or social characteristics and also it was seen a range of crown dieback with different intensity/pattern within stand in individual to group trees.
Farhad Ghasemi Aghbash, Geshin Allah Veisi, Vahid hosseini,
Volume 3, Issue 1 (9-2016)
Abstract

Litter decomposition is the most important way of nutrient entering to soil and soil nutrient availability is highly related to dynamics of nutrients and litter decomposition in the forest ecosystems. This study aimed to evaluate the dynamics of nutrients and litter decomposition in the northern Zagros forests using litterbag technique for 180 days in the Khul Hoare forests located in Baneh city. The litter bags were collected at intervals of 30, 60, 120 and 180 days and the rate of leaf litter decomposition and chemical compounds such as nitrogen, carbon, phosphorus, potassium and calcium were measured. The results showed there was no significant correlation between the rate of decomposition and the initial composition of nutrients and also C: N and C: P ratios. Due to the qualification of leaf litter based on the amount of nitrogen in this study, the average amount of nitrogen in Quercus libani was 1.37%. So Lebanon oak can be classified in the average group and it can be considered as a soil improver species. In the studied litter, phosphorus and nitrogen had a similar performance and their concentration increased over time (7.27 and 30.38 mg/g respectively). While concentration of elements such as calcium, potassium and magnesium was decreased. The nutrient concentration of Quercus libani leaf litter was Ca>N>P>K> Mg.


Ahmad hosseini, Seyed Mohsen hosseini,
Volume 3, Issue 2 (3-2017)
Abstract

Background and objectives: Understanding the spatial pattern of tree species in their social life could have many applications from the standpoint of ecology and applied silviculture for their optimal management. For the purpose of studying the spatial pattern of Quercus brantii and Pistacia atlantica in relation to stand form and topographic factors, we selected the Manesht forested area in northern Ilam.
Materials and methods: In this research, 75 sample plots (with 2000 m2 area) were chosen, using systematic random sampling method within the study area. The variables in the plots comprised the number of tree species and topographic factors. The dispersion indices of interest included Morisita, Sstandard Morisita, Green, Lioyd and variance to mean ratio. The calculation of quantitative indices, by running the relevant computational formulas, was performed by Ecological Methodology Software. In addition, in terms of accuracy, the efficiency of quantitative indices was studied and compared. Statistical analysis of data was carried out using SPSS Software.
Results: The results showed that, for Q. brantii, the values of variance to mean ratio, Morisita and Lioyd indices and for P. atlantica, the values of Morisita, Green and Lioyd were higher in standard and coppice stands than the coppice and standard stands. For both species of Q. brantii and P. atlantica, all of the indices in question increased with increasing elevation, and the highest values of indices were obtained in 2100-2300 m a.s.l. For Q. brantii, the values of all of the indices increased with increasing slope, and the highest value was obtained in the slope class more than 60%. Moreover, for P. atlantica, the highest values of all indices were obtained in the slope class of 30-60%. The spatial pattern in classes of 0-30% and 30-60% was clumped and in more than 60%, it was regular. For Q. brantii, the values of all indices and for P. atlantica, the values of Morisita and Lioyd were the highest in the southern direction. The results of the precision study of the indices showed that for Q. brantii, the indices of Morisita and Standard Morisita and for P. atlantica, indices of Standard Morisita and Green had the highest precision.
Conclusion: It was concluded that the value of dispersion indices (especially more accurate indices) varies by environmental factors and thus changes in values could be used in forest dynamic studies and the interpretation of changes in forests.


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