h. jahanbazi

Oak trees are hosts of diverse gall-inducing parasites, but the information about the leaf gall is poorly understood. This study aims to examine the weight of leaf galls on oak trees (Quercus brantii Lindl.) in different crown directions with different growth forms (high-forest and coppice) on different geographical slopes in healthy and dry stands of Kohgiluyeh and Boyer-Ahmad province, Iran. For this purpose, two sample plots with a one-ha area involving decline traces of trees (dry) and two sample plots without dieback (control) on the northern and southern slopes in forest sites of Boyer-Ahmad and Dena counties of Iran were selected by field survey. After recording the quantitative variables (DBH, mean diameter of sprout-clump, height and canopy cover), we collected 20 leaves from each direction of the crown of each tree sampled. In the laboratory, the galls were removed from the leaves and weighed. The results showed that there was no statistical significance between the different crown directions of the sample trees in both growth forms, although, in most sites, the northern direction of the trees had more galls. Leaf samples from the south decline site were found to have significantly more gall weight than samples from the other sites in both growth forms. Also, high-forest trees had significantly more leaf galls on their leaves than the coppice trees did. Monthly average temperature and altitude seem to be two determining factors in leaf gall development of the oak trees.

In forest ecosystems, forest production, storage and carbon flow are calculated based on biomass measurements. The aim of this study was to compare the biomass and carbon stock of the above-ground, litter and soil in the oak decline and control plots in Chaharmahal and Bakhtiari province. Four one-hectare sample plots were selected in the healthy (control) and declined stands of oak. Then quantitative information of all trees were measured. Allometric equations were used to calculate the above-ground biomass and carbon stock. Ten microplots were established in each sample plot and all litters were collected. Wet and dry weights and carbon content of the litter samples were measured. To measure soil organic carbon, five soil samples were taken in each sample plot. The results showed that above-ground biomass in the control and decline sample plots were 31.4 and 15.8 tons/hectare respectively. Also, the average of the above-ground carbon stock in the control and decline plots were 15.1 and 7.7 tons/hectare, respectively. The mean of litter carbon in the control plots was 1584.1 kg/ha and in the decline plots was 1148.6 kg/ha. The amount of carbon, nitrogen, phosphorus and soil moisture content showed a significant difference between the control and decline plots. The results of this study indicated significant changes in biomass, carbon stock and soil in declined stands of oak which may cause irreparable damage to the Zagros forest ecosystem, in the long term. This issue highlights the need for the attention of managers and decision makers of natural resources, regarding the provision of management solutions to control this phenomenon.