LAUSR

Oak decline is an expression describing death and drying up of oak trees. The present research evaluated the relationship between various geographical directions and altitude and some factors predisposing Persian oak (Quercus brantii Lindl.) decline, such as charcoal disease and oak wood boring insects in a 100 hectares area of the Shurabad forests in Lorestan Province of Iran. A 200 by 200 m sampling network was first designed on a regular-random (systematic) basis, and the trees were sampled from 1500-m2 circular plots. Information including hillside direction, altitude, infection site (on tree crown or on trunk), type of infection (charcoal disease or wood borers), crown vigor, and heights of the infection sites on the trees was recorded in each sample plot. Results indicated the significant relationships of infection type and severity with altitude, geographical direction, slope, and location of the sample plot at the significance level of 5%. Wood borers were the most common cause of infection. There was very little attack by charcoal disease in the study area. Most diseased trees were in the valley, in a northerly direction, at the 1101–1150 m elevation class and the 41–50% slope class. There were very few healthy trees in the study area, and most of them were on the ridges, in a southwesterly direction, at the 1151–1200 m altitude class and the 11–20% slope class.