1Department of Forestry, Natural Resources and Marine Science Faculty, Tarbiat Modares University, Noor, Mazandaran, Iran
2Department of Forestry, Natural Resources and Marine Sciences Faculty, Tarbiat Modares University, Noor, Mazandaran, Iran
3Department of Forestry, Research Institute of Forests and Rangelands, Peykanshahr, Tehran, Iran
4Department of Forest Ecology and Silviculture, Forestry and Wood Technology Faculty, Gorgan University of Agriculture Sciences and Natural Resources
*Corresponding Author Email: hosseini@modares.ac.ir
Online published on 6 December, 2013.
This research carried out to study the relationship between tree competition and Persian oak (Quercus brantii) dieback and mortality in different site conditions and stand structures in Shalam oak forest which located in north of Ilam province, western Iran. We divided study area into 20 homogenize units based on topography using GIS. Then we established 6 transect with a length of 100 m in each landform unit and determined 5 random points with interval of 25m on each transect and marked the closest live and dead tree to them. To each focal tree we measured the distance, species, Diameter at breast height, crown diameter, height and crown dieback percent of neighbor trees. Competitive condition of focal live and dead trees was computed by Hegyi index. The results showed that the amount of tree competition varied among units. Also the results of correlation and Principal component analysis (PCA) showed the significant positive and direct relationship between competition and tree dieback amount. The lowest and highest amount of tree dieback was found respectively in units those had the lowest and highest amount of tree competition. Also the amount of tree competition had inverse relationship with crown diameter of focal tree and direct relationship with crown diameter and height of neighbor trees and crown dieback percent of focal trees.
tree competition, tree mortality, Persian oak, Zagros
