عنوان مقاله [English]
Background and objectives: One of the main problems in Zagros forests is oak trees dieback. What is certain and important is that the tree dieback crisis caused the declining of oak in oak forest of Zagros. Oak decline is characterised by crown thinning, foliar necrosis and progressive death of primary leaf-bearing branches and the emergence and subsequent decline of foliage. A range of biotic and abiotic factors has been shown to contribute to the decline. However, no satisfactory investigation has been established to explain the distribution.
Materials and methods: The aim of this study was to investigate the spatial variability of Oak decline and it’s relation to tree properties in Zagros Forest of Kermanshah (Gahvareh). In this order, 150 hectares of Gahvareh forest was selected and then 67 sample plots (400 m2) were used in a 100 × 100 m sampling grid. In each of the plots the the number of healthy trees and their canopy cover, the dieback and trees with dieback features including diameter, height, crown diameter, average canopy cover, the number Search trees were recorded. Then the spatial continuity, using geostatistics (variogram) were described.
Results: The results of the Pearson correlation coefficient indicates that dieback has a significant positive relationship with the feature tree dieback including diameter ،height, crown diameter, canopy cover is a significant and positive relationship between the number of sprouts. As well as between the dieback and features healthy tree such as the number of trees and average canopy cover and there is a significant negative relationship variograms of variables revealed the presence of spatial autocorrelation except for the number of shoots have the spatial structure.
Conclusion: Overall analysis of the spatial structure of healthy and dead tree dieback and features show that the structural component of the variance components of random variance prevails. The variables studied occurred in a relatively large area, indicating the spatial structure of large, uniform distribution and continuity in the desired location in variable amounts. The similarity in the effect of dieback and features trees with dieback (collar diameter, height, crown diameter, average level of cover and canopy cover) and also a significant positive correlation between them, represents the close spatial relationship between the dieback and trees have been dieback features. Given the significant negative correlation between the dieback and characteristics of healthy trees (number of trees and average level of cover), it can be stated that the spatial variability characteristics of healthy trees, the dieback affects as photos.