مجله جنگل ایران
سال هشتم شماره 4 (زمستان 1395)

According to the importance of regional differences in the country’s strategic plans and also direct role of urban forests in sustainable development of cities, this research at identifying the regional differences from the perspective of urban forestry indicators. For this purpose, initially, six indicators have been identified and their related data has been gathered for nine urban districts of the Tehran from Tehran Municipality and Park and Green Spaces Organization. In order to weight the indicators for providing Tehran urban forest’s structural indicators, the factor analysis method has been used and structural indicators for the districts have been calculated and categorized. Dividing by the average method was used to remove the differences in scales. The sum of squared rotated loadings and sum of squared extracted loadings showed three components totally can reveal 87.60% of the variances. According to the results, Tehran districts 4 and 22, have been mainly ranked first and second from the aspect of urban forest’ indicators and have better conditions compared with other districts. While district 11, 16 and 10 in Tehran are ranked among the last. For the first time, in this research, providing structural indicators for Tehran urban forests was done, with the aim of more alignment of approved projects with the needs of citizens and improving their quality of life.

Judas tree (Cercis siliquastrum L.) is a suitable species for improving the soil nitrogen fixation and creating the natural landscape in parks and roadsides. This study was aimed to investigate the growth, development and drought resistance of Cercis seedlings by applying different irrigation periods. First, the seeds of Cercis were treated to germinate and reach to seedling phase (30 cm in height) for 90 days. Then, the seedlings were examined in a completely randomized design with four irrigation periods (4, 8, 12, and 16 days) and three replicates for 70 days. Irrigation significantly affected all morphological characters whereas stem length, root length, specific leaf area, shoot dry mass, leaf dry mass (p≤ 5%) and other characters (p≤ 1%) were different among the irrigation periods. The highest stem length, collar diameter, leaf number, leaf area, shoot dry mass, leaf dry mass, collar diameter growth, height growth and survival rate were observed in 4-day irrigation period. Seedlings with 8-day irrigation period had the greatest root volume, root dry mass and plant dry mass. This is while that, the 8-day irrigation period induced the greatest root length, specific leaf area and root/shoot ratio. The results revealed that the 4-day irrigation period was suitable for raising the Cercis seedlings; however, due to the satisfactory survival and growth, as well as the low cost and easy maintenance of seedlings, the 8-day irrigation period can be a good alternative for seedling production of this species.

Air pollution has advers impacts on human beings, animals and plants. Leves and flowers are the most sensetive part of plants which are used as bioindicator under air pollution stress. Reactive Oxygen Species (ROS) increases in stress conditions, subsequently, plants have various changes in their physiological and biochemical properties in response to air pollution. The present study was conducted to investigate the effects of air pollution on superoxide dismutase (SOD), ascorbate peroxidase (APX), and guaiacol peroxidase (GPX) activities as well as chlorophyll and carotenoid contents of Pinus eldarica and Platanus orientalis leaves in Tehran. Results showed that SOD activity of Pinus eldarica in unpolluted area was less than that in polluted area, and also this value for Platanus orientalis in unpolluted area was less than that in polluted area. The highest and lowest APX activity was found in Pinus eldarica of polluted area and Platanus orientalis of unpolluted area, respectively. In addition, GPX activity of Pinus eldarica was more than that of Platanus orientalis and this value in polluted area was more than unpollluted area for both species so that its maximum and minimum was respectively found in Pinus eldarica of polluted area and Platanus orientalis of unpolluted area. chlorophyll a, total chlorophyll, and carotenoid in polluted area was more than that in unpolluted area, while this value was not statistically significant for chlorophyll b. In general, free radicals are increased under stress conditions. Hence, the activity of antioxidants has significan impacts on alleviating the damages of ROS. Enzyme activity was increased, while chlorophyll and carotenoid content were decreased in both spices under pollurtion stress. It can be concluded that Tehran has high concentration of pollutants which can change biochemical and physiological properties of tree leaves.

Yellow mistletoe (Loranthus europaeus) species is a semi-parasitic plant threatening the Zagros forests, hence idendification of infectious areas are important for its control and management. For this purpose, a forest patch ca 37 ha with different intensities of yellow mistletoe was selected in Ilam province. In order to classify the yellow mistletoe, worldview 2 satellite image dated November 14, 2010 was used. After radiometric and geometric corrections, the image was segmented by NDVI and PCA as thematic layers with different band weights and 29 scale parameter. Different algorithms such as K Nearest Neighbor (with different K parameter), Support Vector Machine (with different C parameter), and Random Forest (with different number of trees) based on object-based approach with 18 spectral and shape features were then compared by using 312 ground truth points. The overal accuracy for K Nearest Neighbor, Support Vector Machine and Random Forest algorithm were obtained 85.1%, 87.4% and 92.9%, respectively for infection classifaication into four categoreis (non, low, mediom and severe infections). Random Forest algorithm with 1000 trees was the best one in indentifying the various intensities of infections. It is concluded that identification of yellow mistletoe in Zagros by using worldview 2-satellite image and object-based classification is possible.

The certainty of forest resources evaluation regarding to emission of atmospheric carbon dioxide could be increased by estimating the organic carbon pool of forest floor. This research aims at exploring the relationship between plant diversity in the different stories pertaining to forest physical characteristics, and variation of carbon sinks of forest floor. The current research was done in control compartment located in the third district of Glandroud forests. The sample plots with 400 m2 area were sytemetically established in the study area which were separated by a distance of 100 m from each other. Four 1 m2 and 50 × 50 cm2 plots were marked at the center and corners of the sampling plot to measure and collect the herbal plants and litter, respectively. 80 g of each herbal and litter sample was separated after weighing in the field and the all samples were oven-dried at 65ºC for 48 hours. Carbon content of each sample was measured and calculated by placing each sample in the heat oven. The results showed that the tree diversity indices are independent of physiographic changes in the studied forest. However, abundance and dominance of herbal coverage were significantly different at altitude and aspect classification, respectively. Among all the studied carbon sinks, carbon sequestration of litter was significantly different at slope classification. The final result indicated that there was no significant correlation between plant biodiversity and amount of carbon sink in grass coverage. In other hand, the significant correlation was found between carbon stock of litter and indices of Shannon, richness, and importance value of tree storey.

Studying the relationship between site productivity, as a key indicator in forest management, and environmental variables is an important issue in forestry. In the past, studying such a relationship was done using linear regression model, but nowadays ensemble techniques like random forest are used. A stratified random sampling method based on landform was used to locate 114 0.1 ha circular sample plots in beech dominated forests. The height of five largest diameter beech trees within each plot was recorded as dominant height along with elevation, azimuth, and slope of the ground. In addition, at the center of plot, soil samples from first layer (0-10 cm) were taken for analyzing several soil variables. Evaluation of site productivity by using random forest technique showed that about 90% of variability in oriental beech productivity could be justified using environmental variables. Phosphorous and percentage of nitrogen, as edaphic variables, and slope and altitude, as physiographic variables, are among the most important variables affecting the beech forest productivity. Using criteria including R squared and adjusted R squared showed random forest technique had very good performance in assessing beech forest site productivity. These analyses underscore the importance of ensemble techniques in forest ecology studies and furnish framework for future modeling of beech forest productivity in relation to environmental predictors.

By examining the forest structure not only the forest conditions such as species composition, story and succession are determined, but also the future of forest in relation to growth, species diversity changes, canopy cover and basal area could be predicted. The purpose of this study was to quantify the stand structure and forest stands dynamics through triangle structure method. The current survey was carried out in compartments 305, 306, 309, 310 and 311 about 150 ha in Gorazbon district of experimental Kheyrud forest. For this purpose, two full calipering periods were used. The frequency and stocking volume at each diameter class were then obtained. The results showed that there was not significant differences between two inventory periods about beech, hornbeam, and maple individuals and their volume by using paired t-test. Generally, due to subtle changes, it is concluded that a 10-year period is not appropriate to examine the considered factors. Therefore, it is necessary the changes monitoring is done by repeated inventories in successive 10 year periods. Therefore, it is suggested the monitoring methods and control of forest structure dynamics over times through reliable data, as a solution for the forest management practices to increase the quality and quantity of forest stands by management interferences in the nature oriented silviculture context are specially considered.

Abiotic environmental stress is an important factor in the limitation of plant growth and production. At the same time, environmental stresses such as drought and salinity become more widespread globally. One of the resistance mechanisms against the stress is symbiosis with soil microorganisms, including arbuscular mycorrhizal. In order to evaluate the effect of water stress on the growth and antioxidant enzymes activities of Pistachio mycorrhiza seedlings (Pistacia vera L.) inoculated seedlings with mycorrhizal fungi with Funneliformis mosseae produced. In this study the vases irrigated for two years to complete establishment seedling for (three time in weeks), then drought stress was imposed in during nine days. After measuring growth factors, the effect of the fungus growth factors such as stem length stem diameter, branch length, branch diameter and leaf area index was statistically significant different in mycorrhizal seedlings ( P

The oak leaf-roller moth (Tortrix viridana L.) damages the Zagros forests greatly by feeding upon leaves and sprouts of different species. The current study was carried out in 2015 in order to investigate the influence of cardinal directions on quantity features of oak tree and on the demographic changes of oak leaf-roller moth in Ghabr-e-Hosein area (Piranshahr) located in oak forests of west Azerbayjan. In every main geographical directions 30 gall oak trees (Quercus infectoria) and 30 Lebanon Oak trees (Q. libani) was measured using transect method and the pest larvae were counted from the branch tip inward and also quantity features of the host trees were recorded. Results showed that the maximum crown diameter was on the east while the minimum was on the south and north. The highest and lowest diameters at breast height (DBHs) were on the south and north, respectively. In addition, results showed significant differences (p

In forest ecosystems, canopy gaps play an essential role in soil nutrient cycling. In this study, the relationship among different areas of canopy gaps (200, 400, 600 and > 600 m2), biological (e.g., earthworm biomass, microbial respiration, N mineralization, C microbial biomass, N microbial biomass and particulate organic matter of C and N) and also physico-chemical (e.g., bulk density, texture, moisture, pH, organic C, total N and available P, K and Ca) properties, from the top 15 cm of soil, was studied in Beech forests of Sardabrood located in Kelarabad. Three points were considered in center of each canopy gap and also closed canopy, soil samples were taken and mixed due to transferring to laboratory for analysis. According to findings, whole of soil physico-chemical properties (except for silt content and available Ca) were significantly affected by different canopy gaps areas. Also, the highest earthworm's assemblage was under closed canopy and the population was decreased with increasing of canopy gap areas. The characters of microbial respiration, N mineralization and particulate organic of C and N showed ascending trend with increasing of canopy gap areas. Carbon microbial biomass was significantly higher under closed canopy than in different canopy gap areas, whereas the highest amount of N microbial biomass was found within 400 m2 gap areas. According to our data, the highest values of soil chemical and biological properties were related to 400 m2 gap areas. In larger canopy gap areas, soil nutrient elements are decreased due to high decomposition and leaching.