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Hojat Alah Omidi, Javad Mirzaei,
Volume 2, Issue 1 (9-2015)

Natural regeneration is the most important principle to maintain and sustain of vegetation in each region, therefore, doing the research about the relationship between natural regeneration and environmental factors can be useful for conducting a better management in these regions.Therefore, this study aimed to investigate the effects of physiographic factors and soil parameters on natural regeneration of trees and shrubs species in the forest of Baye Mountain in Eyvan city, Ilam province. Using systematic random sampling, 27 plots were implemented in the area with a total area of 900 square meters. Then environmental factors (physiographic and soil) and the number of natural regeneration were studied and measured. Correlation analysis showed that Cerasus microcarpa regeneration had positive correlation with OM and Ca and negative with EC. Regeneration of Acer monspessulanum L. had negative correlation with clay, and Amygdalus lycioides regeneration had positive correlation with silt, while there was no significant correlation between other species and other soil factors. The results showed that elevation had significant effects on natural regeneration of Cratagus pontica and Amygdalus lycioides, while the slope of gradient hadn't any significant effect on regeneration. Only, aspect had significant effects on Cerasus microcarpa regeneration, and regeneration of this species in the eastern and northwestern direction was more than other aspects.

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

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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