مجله پژوهش و توسعه جنگل
سال نهم شماره 2 (تابستان 1402)

One of the main destruction factors of oak forests is the oak leaf roller Tortrix viridana L. which causes a lot of damage to these woods by feeding leaves and buds of oak trees. The purpose of study was to investigate the population changes of this pest in different altitudes. This research was conducted in 2018 in Perdanan and Mirabad. In each region, in three elevation classes, transects with 100 meters’ intervals, and in each elevation class, 30 individuals of Quercus infectoria Olivier, which were located along the specific transect and in terms of appearance approximately similar, measured. In each tree, four branches were selected in four main directions (each direction of a length of 50 cm) and the pest larvae counted and the diameter of the branches were measured. Data were analyzed by SPSS 18 software and comparison of means was performed using Duncan's multiple range test. Results showed that according to the climatic diversity of two regions, the number of T. viridana larvae in the Perdanan was higher than Mirabad. Also, the number of larvae was recorded for both areas in the 1200-1300 meters’ elevation, which shows that the favorable conditions for larvae activity. The elevation class had no effect on distribution of pest in directions of the tree crown. The highest number of larvae in all three elevation classes was recorded in the eastern direction of the tree and its lowest amount were recorded in the west direction.

Dust particles can cause disturbance in photosynthetic activities by passing through the openings and thus reduce plant growth. The present study examines the effect of cement dust pollution on the characteristics of leaf stomata in two important tree species of Hyrcanian forests in northern Iran. For this purpose, the leaves of oak (Quercus castaneifolia C.A.M.) and common hornbeam (Carpinus betulus L.) were sampled in two polluted and control sites around the Mazandaran cement factory. The characteristics of density, width, length, perimeter, and area of stomata and guard cells were measured. The results showed that the average stomatal density for oak and common hornbeam in the polluted site (36.1 and 6.6 stomata per mm2, respectively) is significantly higher than the control site (24.3 and 2.5 stomata per mm2, respectively). Based on the results, the characteristics of stomatal width and length as well as guard cell width and length in oak did not show any significant difference between the two polluted and control sites. In common hornbeam species, the average width and length of the stomata in the polluted site (40.5 and 75.2 µm, respectively) were significantly lower than the control site (46.8 and 90.4 µm, respectively). Also, in the oak species, the ratio of stomatal length to width in the polluted site (3.5) was significantly higher than in the control area (3.1), but no significant difference was observed in the common hornbeam species. Finally, the oak species showed better resistance than the common hornbeam species by increasing the stomata density without a significant change in the characteristics of the length and width of the stomata and the guard cell.

Despite progress in full mechanization, motor-manual logging technologies still dominate in many countries, including in North plantation forest of Iran. Motor-manual timber harvesting is considered to be one of the most dangerous working operations. The physical demands of work are still one of the crucial workload factors in most jobs in the forestry sector, especially those connected to manual loading. The aim of the study was to investigate the physiological workload of a worker during manual loading in a poplar plantation stand in the north of Iran. Physiological responses were assessed on a sample of 12 workers manual loading during a normal working shift. Polar heart rate monitors were fitted over a period of a week in order to record ‘working’ heart rates. The collected data were used for the calculation of heart rate indices that determine the strain of the subjects. The average mean heart rates during work time, rest time, and maximum heart rate were 132.42, 79.42, and 175.16 bpm respectively. The results showed that the mean level of physical workload was 55 which correspond to very heavy work. The study results also showed that age and body mass index of workers is significantly effective on HRw and weight of workers on HRw and HRmax, respectively. The results revealed high physiological demands of manual loading. Increasing the mechanization level with investment in modern equipment may be proving beneficial in enhancing workers health and safety.

Current study reviews effect of the Darabkola forest plant communities on Carbon sequestration in soil and Above Ground Biomass (AGB). It compared five natural communities, including Parrotio persicae-Carpinetum betuli, Zelkovo carpinifoliae-Quercetum castaneifoliae, Solano kieseritzkii-Fagetum orientalis, Aceri velutini-Parrotietum persicae, Euphorbio amygdaloidea-Fagetum orientale, and one Maple plantation stand. Sampling was done using systematic randomized with 400×400 meters dimensions. After removal of marginal points, soil samples were collected from center of 163 plots with 20×20 meters dimension. Results of ANOVA, mean comparison, and PCA showed that the highest soil Potassium belongs to the plantation stand (336.96±18.97), while the least one, belongs to Solano kieseritzkii-Fagetum orientalis (160.25±10.75). On the other hand, soil Phosphorus was the highest in the Aceri velutini-Parrotietum persicae (4.65±0.55), and it was the lowest in Solano kieseritzkii-Fagetum orientalis (1.95±0.14). Aceri velutinid-Parrotietum persicae (34.80±2.08) and Solano kieseritzkii-Fagetum orientalis (22.73±1.22) had the highest and the lowest soil moisture content, respectively. However, the study proved that different communities did not affect soil sand percent and carbon sequestration. Zelkovo carpinifoliae-Quercetum castaneifoliae (242.82±23.22) had the highest, and plantation stand (54.78±5.55) had the lowest carbon sequestration in AGB.

One of the most important goals of the ecological management of forests is to enhance the complexity of the structure of the forest stands. Also, despite the recommendation to increase mixing, the consequence of the presence of rare tree species on the forest ecosystem functions has not been well clarified. This research was conducted to analyze the presence and abundance of rare tree species on the structural complexity index in beech stands. the number of 12 one-hectare study areas with the presence of rare tree species was selected and after measuring the structural features, the multivariate complexity index was determined in each of the plots. We employed ten variables including stem per hectare, mean diameter at breast height, coefficient of variation of dbh, diameter Gini coefficient, number of trees with a diameter larger than 100 cm at breast height, the ratio of the number of trees in different stories, the faction of canopy gaps, amount and volume of dead woods and tree size variation to the calculation of this index. Comparing the correlation between the relative importance value of beech, Maple, and other rare tree species with the structural complexity index revealed the differences in complexity variation toward the rising in the abundance of tree species. Accordingly, beech and hornbeam, as the two dominant tree species with the highest relative value, are weakly correlated with this index. While the maple and other rare tree species including alder, elm, and lime positively correlated with increasing complexity in the structure. According to the positive effect of the presence of rare tree species on the complexity of the structure of forest stands, it is recommended to the retention of rare tree species in stands to increase the complexity of the forest stands structure.

Forest structure is a key element for assessing the ecological functions and services in forest ecosystems, which can be described and quantified using forest structural indices. This research was conducted with the aim of quantifying the structure of pure beech forests using spatial indices of forest structure in the Hyrcanian forests of Iran. For this purpose, 90 permanent sample plots of 1000m2 area in three pure beech forests (30 samples in each forest) were established based on a systematic-random grid of 150×200m and the variables of DBH, total height, species and spatial coordinates of all trees greater than 7.5cm in the sample plots were recorded. Then, the structural characteristics of the forests were quantified using O-ring statistic and indices of diameter and height differentiation, diameter and height dominance and Mingling. The results showed that the distribution patterns of trees in the pure beech forests is mainly random, the degree of diameter and height differentiation is average, the degree of species mixing is low, the top height is about 33.5m, the forests are two-storied, trees in terms of dominance indices are co- dominant and the average tree to tree distance is less than 3m. These spatial and quantitative indices of the forest structure can be used for management, planning and silvicultural interventions in the forests. Furthermore, by using these indices with permanent sample plots and assessing their changes over time, it is possible to long-term monitoring and comparing the forests.

In this study, Shafarood watershed, in Guilan province, was investigated in terms of the implementation of value chains ecotourism, timber harvesting, and wood farming based on the prioritization of criteria and sub-criteria. To collect data observations, interviews and questionnaires were conducted with experts (55 people) selected based on their expertise and experience. Questionnaires were analyzed the pairwise comparison method. The results show for the ecotourism value chain, criteria vegetation diversity, distance from the spring, and distance from urban centers, as well as the sub-criterion, maximum 5 km distance from urban were important with a final score of 0.026, for the timber harvesting value chain, the number of trees per hectare, altitude above sea level, and volume of forest stand and the sub-criterion of terms and conditions, were important with a final score of 0.040, for the value chain of wood farming, criteria of soil structure condition, precipitation and erosion rate, and the sub-criterion of humid climate were chosen with a final score of 0.036. According to the results, 18.21 percent of the total area (6637.59 ha) was suitable for implementing the ecotourism value chain, 31.08 percent of the total area (11321.98 ha) was suitable for the timber harvesting value chain and 0.57 percent of the total area (210.63 ha) was suitable for the value chain of wood farming, which is recommended to be taken into consideration for the economic prosperity and dynamism of the area.

Iron wood (Parrotia caspica (D.C) C.A. Mayer) is one of the endemic tree species of Iran that is widely distributed in Hyrcanian forests from west to east. Due to the fact that climatic factors in the northern forests are variable, the relationship between the ecological conditions of the habitat and the leaf stomata of Iron wood tree species was investigated in this study. For this purpose, leaves of 10 populations were collected from three provinces of Guilan, Mazandaran and Golestan and the morphological characteristics of their surface, density, length and width of the stomata were investigated. Also, habitat characteristics of diameter equal to tree trunk, altitude of habitat, temperature and rainfall were used for climate modeling. The results showed that with a 99% probability there was a significant difference between the stomata characteristics of Iron wood trees in different habitats (P<0.001). The trend of stomata density changes from west to east of northern forests was decreased, but stomata area increased from west to east. The predicted model showed that altitude and temperature had a significant effect on stomatal density (P<0.001). Temperature and rainfall had a significant effect on the stomata area (P<0.001) but the effect of altitude and diameter at breast height on the stomata area was not significant. In general, it can be said that the characteristics of the stomata are closely related to the climate conditions prevailing in the habitat.

Soil microbial respiration in forests constitutes a significant share of carbon dioxide emissions in terrestrial ecosystems and is very sensitive to environmental changes such as soil temperature and moisture and the type of vegetation. In this study, soil microbial respiration and two environmental factors including temperature and soil moisture were conducted in five forest types in four seasons. Soil microbial respiration was measured by the closed bottle method, soil moisture in the laboratory and soil temperature with a thermometer simultaneously with soil sampling in areas of surface soil (0 to 10 cm depth), and the relationships between soil microbial respiration and environmental variables were analyzed. The results showed that the soil microbial respiration rate is significantly higher in the wet period (spring). The pure Quercus libani types with an average of 0.090 throughout the year had the highest amount and the pure Q. infectoria types with an amount of 0.078 mg/g of soil per day had the lowest amount of microbial respiration. Also, no significant difference was observed in soil microbial respiration between forest types.