The relationships between the rate of oak trees decline and forest types, soil characteristics and topographic conditions in Ghalaje Forests of Kermanshah, west of Iran

In order to investigate the decline of oak trees in Zagros forests in relation to forest soil characteristics and topographic conditions, Ghalaje Forests with an area of 500 ha in Kermanshah province were selected. For forest classification, systematic-random sampling was used with a 200×150 m grid by 50 m transects. Work units were specified based on the land form, aspect, altitude, slope degree and rate of oak decline. Soil samples were taken within work unit to analyze soil texture by hydrometer, soil nitrogen by Kjeldahl, bulk density by clod method, organic carbon by Black and Walkey method and lime percentage with Calcimetri method. The results of analysis of variance showed that the number of dieback trees was significant (P