Investigation of Beech Increment in Elevation Levels with Trend of Climatic Changes (Case study: Asalem basin)

Fagus orientalis as a climatic specie is under climatic varying condition and changing climatic elements has a direct impact on its growth and distribution. The present study was conducted in the Asalem forest, Guilan province, located in north part of Iran. 180 sample discs were selected in terms of different three elevation level with respect to climatic data in 38 years duration. Results revealed that the growth trend with 7-10 years period were different with diameter class. The growth trends index had no conformity with temperature and rainfall at winter and autumn; however there were conformity with temperature index in small diameter class and with rainfall index in large diameter class in the season of spring and summer.