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Application of probability distribution in order to fit the diameter and natural and man-made height of oak species in two stands in hyrcanian forests

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International Journal of Biomathematics 2016年第3期9卷 293-301页

作者： Farah Mohammadi Mir Mozaffar Fallahchai[ Seyed Armin Hashemi Department of Forestry Faculty of Natural Resources Lahijan Branch Islamic Azad University Lahijan Iran

In order to study the fitting of some characteristics like low diameter at breast height （DBH）, the height and height to the beginning of crown of the Oak species in two man-made and natural forests.of this species in north of Guilan＇s forests. Tooshi and Radarposhte forests.were selected. A 100% inventory was done on a one-hectare sample plot in Tooshi man-made forests.and on a two-hectare sample plot in Radarposhte natural forests. The results from this study showed that, in order to fit the diameter and the height of the Oak trees in man-made stands, Johnson＇s SB and normal statistical distributions have more capabilities and the three-parameter gamma and the three- parameter Weibull distributions are appropriate for diameters and heights of the natural Oak trees in Radarposhte forest, respectively.

关键词： Fitting diameter height Oak hyrcanian forests.

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Primary Host Tree Species of the Gypsy Moth Lymantria dispar （Lepidoptera： Lymantriidae）in hyrcanian forests

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Journal of Agricultural Science and Technology(B) 2011年第3期1卷 342-346页

作者： G. Hajizadeh M. Reza-Kavosi Department of Forest Ecology Faculty of Forestry Gorgan University of Agricultural Sciences ＆ Natural Resources Beheshti St. 386 Gorgan Golestan lran

Invasions by exotic insects and diseases are one of the most important threats to the stability and productivity of forest ecosystems around the world. Lymantria dispar （Lepidoptera： Lymantriidae） in Iran was observed for the first time in 1937 by Jalal Afshar in oak forests.of the Guilan state region. Since its introduction, gypsy moth has spread to the northern, western and south-western regions of Iran. The largest outbreaks of gypsy moth occurred in the Talesh Oak forests.of the hyrcanian zone in 1975. The gypsy moth is a highly polyphagous folivore species that feeds on over 300 species of woody plants. Among its most preferred hosts are oaks and aspens. Some trees are resistant to the gypsy moth including honey locust, black locust, silver maple, green ash, dogwood, sycamore, horse chestnut, firs, and tulip trees. Defoliation during severe outbreaks alters the appearance of forest habitats and leads to tree mortality and changes in stand composition. This study was conducted during 2008 and 2009 in an effort to determine the primary host tree species that the gypsy moth infests in the hyrcanian forests.of lran. For that purpose all egg masses in the area were counted and conclusively significant differences in defoliation levels among tree species were found. The primary host tree species of gypsy moth in Iran was Persian ironweed, Parrotia persica.

关键词： Gypsy moth Lymantria dispar host tree species Parrotia persica persian ironweed hyrcanian forests.

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