مجله پژوهش و توسعه جنگل
سال یکم شماره 3 (پاییز 1394)

The forests in Zagros vegetative area are important due to their geographical situation, ecosystem performance, and biodiversity. Green oak leaf roller (Tortrix viridana L.) is one of the most important pests which feeds on oak leaves and sprouts and damage them greatly in Zagros forests. Considering the fact that the larva of this insect has different reactions to feeding upon the leaves of Quercus infectoria and Q. libani in their individually and social lives, measuring its social and individual feeding behavior was investigated in the current study. Collected leaves of these oak species were transferred to laboratory and were stored under 25°C and suitable photoperiod conditions (with two individual and group feeding methods) and were given to the fifth instar larvae of the pest. In the group treatment, 20 replications (each replication with 10 larvae) and in the individual method, 40 replications (each repetition with 1 larva) were considered for each host. The indices of relative consumption rate (RCR), relative growth rate (RGR), efficiency of conversion of ingested food (ECI) and efficiency of conversion of digested food (ECD) were measured. The results of the conducted t-test indicated that the degree of larval biomass, RGR, ECI, and ECD are significantly higher in group feeding method compared to individual feeding (α=0.05). In fact, although larvae eat more when they are individually being fed (due to lack of competition stress), they produced more larval biomass in group feeding method despite they ate less (smaller RCR).

Today¡ poplar plantation is considered an important forestry practice for preservation of carbon pools and a major source for bioenergy and cellulose. Providing different allometric equations¡ this research presents a model that may improve the biomass estimation of P. deltoides in Talookola Nursery in Sari. A number of 25 cuttings with 25 cm length were planted in 2011 within 1*1 m plots with identical site condition in three-replication experiment. Saplings numbered 4¡ 12 and 18 were randomly selected in three diameter classes (0-1¡ 1.1-2¡ 2.1-3 cm)¡ respectively. The weight/wet weight ratios were measured after roots and stems were oven-dried at 85 ºC for 48 hours. Collar diameter and sapling height were chosen as variables for modeling allometric equations. The results showed that the logarithmic model related to above-ground biomass including collar diameter (D) and logarithmic models including product of diameter square and height (DBH2 × H) associated with below- and total ground biomass had the highest accuracy with the best goodness of fit data. Moreover¡ multivariate empirical models which did not have multicollinearity (VIF

Working in the forest always has been associated with accidents for employees and felling and bucking as logging components have a special role. In this study, felling and bucking accidents in a period of 20 years (1988-2008) in the forests under the management of the Shafaroud company has been analyzed. This information extracted from accident reporting scheme of safety office of this company. Components of felling cycle identified and the risks of physical factors and the worker error and their consequences were determined. Solutions needed to reduce the incidence of injury were suggested. The most common cause of injury was tree felling. The highest number of accidents occurred among 1993-1994. Most injuries were to the head and face area and more frequent among employees with 10-20 years’ work experience. Accidents were more likely to occur in late morning. The analysis of 194 reported felling and bucking injuries cases allowed identification of high-risk task elements and temporal and logger population injury patterns. Findings from the two analysis were produced a better understanding of key risk areas. The potential for injury between fellers was noteworthy, because felling safety was dependent upon appropriate assessment of hazards and good judgment in respect of decisions regarding the felling and bucking of trees. Safety analysis of felling and bucking and their related accident showed which components of the felling and bucking are more vulnerable and lack of safety could have a lot of potential risks also.

The green oak roller, Tortrix viridana is one of the most important pests of oak in Kurdistan province, west of Iran. According to this fact that chemical control of pests in natural ecosystems is very difficult or impossible, finding the safe ways to control of these pests are necessary. One of the most important methods, is using of natural enemies. The first step in this way is identification of these agents. Tortrix viridana has many parasitoids. In this investigation, we tried to identification of parasitoid flies (Dip.: Tachinidae) and determination effect of them on reduction of pest population. This project was conducted in Marivan and Bane regions during 2012 and 2013. By weekly visiting infested forests, 100 larvae and pupae were collected and transported to the laboratory and placed in containers and by regular visits of cages, parasitoids were collected and parasitism rate and kind of parasitoid in each stage and finally the percentage of parasitism were determined. Three tachinid species were identified: Nemorilla maculosa (Meigen, 1824), Eumea mitis (Meigen, 1824) and Pales pavida (Meigen, 1824).This is the first report of E. mitis from Iran. The results showed that these parasitoids attacked the old larval stages but abundance and parasitism rate of these flies were very low.

One of the main components of forest stand structure is spatial pattern and positioning of trees next to each other. Stand’s spatial patterns are measured and mapped by measuring tree locations in the stand and entering each coordinates into analytical frameworks. The aim of this study was to compare K-Ripley and distance indices in order to determine spatial pattern of Quercus Brantii in Choghasabz forests of Ilam. Using systematic-random sampling with 100×100m dimensions, 53 samples were selected. K-Ripley index and Hopkins, Hinez, Eberhart and C distance indices were used to analyze the spatial pattern in the area. Results of K-Ripley index showed that spatial pattern of oak trees in the study area are random pattern. But the results of Hopkins, Hinez, Eberhart and C distance indices showed a clumped pattern for Quercus brantii in the study area.

The aim of this study was to investigate the role of educational and promotional activities on the Poplar farmers (fertilizing, irrigation, weeding, pest control, pruning, plowing, selecting seedlings and spacing) in the city of Urmia. In this study, descriptive and causal-communication methods were used and poplar farmers in Urmia city were considered as statistical society. Based on random sampling 76 people were considered as statistically samples. Based on the obtained results in the profited by education and promotion activities, it was found that 31.6% of farmers in the field of manure, 50% in the field of fertilizer, 57.9% in the field of irrigation volume, 52.6% in the field of the irrigation frequency, 36.8% in the field of weeding out, 73.7% in the field of pest control, 73.7% in the field of pruning, 78.9% in the field of the plow and 52.6% in the field of spacing, profited by educational and promotional activities low or very low. The results of regression analysis showed that 66% of the variability of manure, 62% of the variability in chemical fertilizer, 61% of the changes in water volume, 81% of the variability in the frequency of irrigation, 67% of weeding out variations, 78% change in pest control, 49% of variability in pruning, 56% of variability in plowing and 89% of variability in spacing, were affected by educational and promotional activities.

Given the influence of number of species on the results of vegetation ordination, this study aims to evaluate how the removal of rare species will impact the results of Principle Component Analysis (PCA) in beech communities in the Hyrcanian Forests of northern Ian. Using random-systematic sampling method with 100*200 m network dimension, 26 sample plots were equally established in managed and control compartments. Percentage cover of each plant species was recorded using Braun-Blanquet scale. PCA was applied to determine the relationship between vegetation and environmental variables. Data were analyzed using Procrustan analysis in the R software. The results showed that the removal of rare species with less than 10% abundance in each sample plot will increases the variance but decrease the Eigen value and that there is a high correlation between the raw datasets and rare species removal. But no significant difference was seen for rare species having less than 5% abundance in each sample plot. It might therefore be concluded that the elimination of rare species with