RT - Journal Article T1 - The Role of Topographic Factors and Land Formation on the Severity of Forest Crown Dieback in the Zagrossian Sector of Ilam Province JF - IJAE YR - 2022 JO - IJAE VO - 10 IS - 4 UR - http://ijae.iut.ac.ir/article-1-1079-en.html SP - 53 EP - 66 K1 - Altitude K1 - Ilam province K1 - Crown dieback K1 - Western oak forests K1 - Slope K1 - Hillshade AB - The purpose of this study was to investigate some environmental factors of Zagros forest dieback. In this regard, raster layers of elevation, slope, aspect, hillshade, toposhape and the land formation of Zagros forests in Ilam province were prepared. The distribution map of live and dieback forest cover were also prepared, using Landsat 8 panchromatic images. Then, the percentage of dieback forest cover in each specific class of the studied factors was calculated, using geographic information system (GIS). Results showed that 2.37% of the forest cover area is dieback canopy. The difference in the percentage of dieback forest cover between landforms was negligible. Maximum and minimum dieback areas of forest cover were in southern aspects (2.7%) and northern aspects (1.73%), slope class 0%-20% (2.6%) and more than 80% (1.52%), elevation less than 1300 m (3.36%) and more than 1700 m (0.52%), hillshade class 0-102 (2.56%) and 255-204 (0.82%), Gachsaran formation (5.08%) and Asmari-Shahbazan formation (0.96%), respectively. As a result, the amount of dieback in the southern slopes was 35.9% higher than the northern, in low hillshade was 68% more than high hillshade and in low elevations was 84.5% higher than high elevations. It seems that the higher ratio of crown dieback was occurred in the less hillshade and at low elevations, due to higher temperatures and lower soil moisture in these areas, which indicates the effective role of recent droughts in intensifying the process of forest dieback. LA eng UL http://ijae.iut.ac.ir/article-1-1079-en.html M3 10.47176/ijae.10.4.13631 ER -