فصلنامه جنگل و فرآورده های چوب
سال هفتاد و چهارم شماره 4 (زمستان 1400)

Zagros oak forests have changed considerably because of irregular and diverse usage of local people. Sacred groves in northern Zagros forest have almost remained undisturbed, due to their social and religious values for local people. In this study, we attentively investigated and compared soil properties in these stands, as stands that show the less disturbed Zagros oak forests, with surrounding oak woodlands that have been pollarded and utilized for centuries as pastures. Five sacred groves and five adjacent pollarded (Galajar) stands were selected. Five composite soil samples were randomly taken by use of 2×2 m microplots from 0-15 cm soil depth. Paired independent t test was used to compare all five sacred groves individually with surrounding oak woodlands and also to compare all data from both areas altogether. The results showed that there are significant differences between all soil properties but calcium content. Soil organic carbon, total nitrogen, phosphorus, C:N ratio, potassium, electrical conductivity and sand decreased significantly in the pollarded area compared with sacred stands while clay and pH increased. The results also revealed that pollarding (Galazani, Galabori) and long-run exploitations of the conventional ownerships in these forests have significantly reduced soil quality and it will be less fertile if this process continues. High soil quality in the sacred groves indicates the importance of conservation in these stands to improve forest habitat quality in the northern Zagros forests. We conclude that, it is critically important to pay more attention to protecting sacred groves in Baneh County.

One of the causes of instability of sloping hillsides is the construction of forest roads, which leads to soil erosion and its effects. The purpose of this study was to study the effects of litter cover and residuals on runoff and sediment in the cut slope and fill slope of forest roads in the forests of Guilan province. For this purpose, four cut slopes and fill slope were selected and in each of them, four plots (2 m2) with four litter cover and residuals including without cover, 30%, 60% and 90% and with a fixed slope of 30% was measured. Samples were measured after each rainfall with an approximate intensity of 80 mm/h. The results showed that the mean of runoff in the cut slope were 759.3, 748.6, 372.6 and 196 ml/m2, in the fill slope were 216.6, 156.6, 77.1 and 69.5 ml/m2, respectively. Mean of sediment in the cut slope were 1.08, 0.96, 0.13 and 0.07 g/l, in the fill slope were 1.51, 1.06, 0.27 and 0.08 g/l, respectively. The results of analysis of variance showed that there was a significant difference between the amount of runoff and sediment created in the litter cover and residuals classes (P<0.05). The mean of runoff produced in the cut slope was significantly (P<0.05) higher than their mean in the fill slope in all cover percentages. Results of the study showed that litter cover and residuals had a significant effect on reducing runoff and sediment in forests roads.

The forests of the Caspian region are one of the most important forest resources in Iran, but what is seen as a large gap in research is the need to pay attention to the structural dimensions, especially to maintain the structural connectivity of these forests. The aim of this study was to assess and compare the indicators of forest landscape in the Caspian Sea watersheds. At first, the forest layer was extracted from the land cover map and 25 large watersheds were selected to study and compare the connectivity indicators. The connectivity of the terrestrial landscape was analyzed using landscaping metrics and graph theory indicators, by Fragstats and Conefor softwares respectively. Finally, by standardizing the calculated connectivity indicators, a final connectivity score was obtained for each watershed. The results showed that the indicators of forest patches connectivity in the whole Caspian catchment are very low, so that 80% of the watersheds are in the category of very low and low connectivity. Watershed 9 (Sardabroud, Shalmnroud) and 7 (Chalous) are in a very unfavorable situation, and only two watersheds of 14 (Chalav, Panjab) and 4 (Pasikhan), in the area of Chalav and Punjab, in the Haraz River, and the Shakharz, Pesikhan rivers, are in a better situation in terms of connectivity indicators. Considering the importance of preserving the structure and connectivity of forest patches, the results of this study show the need for special attention to the management and restoration programs of these forests.

One of the strategies to promote the survival and growth of forest seedlings in rehabilitating damaged habitats is to identify arbuscular mycorrhizal fungi that symbiosis with the roots of the plants in that habitat and then propagate and inoculate them to enable the productive seedlings. The aim of this study was to identify arbuscular fungi coexisting Greek juniper (Juniperus excelsa M.Bieb.) of Chahartagh habitat (Chaharmahal and Bakhtiari province), and to evaluate the role of these fungi in increasing the viability and vegetative components of mycorrhizal juniper seedlings in three consecutive years. The roots and soil around the rhizosphere of nine juniper trees were sampled completely randomly and transferred to the laboratory in cold conditions (in the icebox). After identifying five species of symbiotic fungi, using identification keys in authoritative articles, the inoculum produced with maize was given to germinated juniper seeds, after 4 months. According to the results, the symbiotic effect of identified and inoculated arbuscular fungi including Ambispora gerdemannii, Funneliformis mosseae , Glomus hoi, Septoglomus constrictum, and Rhizophagus intraradices was positive on root length, shoot height, root collar diameter, and seedling survival. At the end of the third year, about 50% of the control seedlings were destroyed, however, the losses for inoculated seedlings ranged from 17 to 40%. A. gerdemannii and R. intraradices had the most positive effect on plant survival. The growth factors under R. intraradices treatment had the highest amount.

The aim of this study was to develop the Mixed-effects model and compare it with nonlinear models for estimating beech (Fagus Orientalis Lipsky) and hornbeam (Carpinus betulus L.) heights in the Shast-kalateh forests (district 1 and 2) of Gorgan. We applied a systematic sampling method to collect the field data within a 150×200 m network (308 circular plots) and in each plot, tree species were identified and height and diameter at breast height (DBH) of all trees were measured. Model fitting was done in two stages: Fixed-effect approach was used in the first stage wherein candidate models where height (dependent variable) and DBH (independent variable). These were refitted in the second stage using a mixed-effect approach. The adjusted coefficient of determination and root mean square error, were used to assess the models. The results of fitting nonlinear models showed that for the beech, Curtis and Naslund models had the highest coefficient of determination of 0.76 and the lowest root mean square error of 3.35 and 3.40, respectively. For hornbeam, Naslund and Michailoff models with the coefficient of determination of 0.40 and the root mean square error of 2.95 and 2.90 were selected as the best models. The results of nonlinear mixed effects model showed that the R2 for beech and hornbeam species increased by 10% and 30% respectively, and the RMSE improved about 0.65 for beech and 0.6 for hornbeam.

This investigation was carried out to study the effect of wastewater on performance of three clones of Populus nigra. A pot experiment was done in a completely randomized design (CRD) with two factors 1) soil in two levels (soil under wastewater irrigation and soil under well water irrigation) and 2) poplar clones in three levels (P. nigra 62/154, P. nigra 62/127, P. nigra 17/13). After two growing seasons, in three poplar clones, the effect of the treatment of soil affected by wastewater was significant (P ≤ 0.01) on growth properties (plant height, stem diameter, leaf area, biomass of roots, shoots, leaves and total) and uptake and accumulation of micro and macro (NPK) nutrients and also heavy metals in plant tissues compared with control treatment. In three poplar clones, the highest uptake and accumulation of Fe, Cu, Ni, Cr, and Pb took place in the roots and Zn and Mn in the leaves. The three poplar clones did not show significant differences in terms of uptake and accumulation of nutrients and heavy metals in plant tissues; however, the effect of clones on biomass was significant (P ≤ 0.01). The highest values of biomass of leaves, shoots and total were observed in P. nigra 62/154 plants experiencing wastewater. The results of this study demonstrated that wastewater could be used as an important alternative source of water and nutrients for afforestation and wood farming. On the other hand, poplars as a phytoremediator in soil polluted with heavy metals could be useful ....

Plant seeds are the main sources of natural reproduction. Lack of natural reproduction in the Zagros forests is due to lack of healthy, ripe and quality seeds. In addition to the genetic characteristics of trees, environmental factors are also effective in producing healthy and quality seeds. This study wasis performed in order to investigate the effect of above sea level on the quantitative characteristics of Pistacia atlantica seeds in Kolahanokan reserve, which is one of the pistacia atlantica reserves in West Azerbaijan province. Unlike other similar researches, in order to Investigate the effect of sea level, the reservoir is divided into 5 classes with a height difference of 100 meters, including 1550-1650, 1650-1750, 1750-1850, 1850-1950, 1950- 2050 meters more ever, in order to increase the height, the reserve area was divided into 77 sample plots of one hectare (100m × 100 m). In each sample plot, three seed-giving trees including the thickest, smallest and one middle diameter were selected under the same conditions (slope factor, slope direction and soil). A total of 150 trees were selected and 5 clusters from each rootstock were randomly collected in the north, south, east, west and center of the crown collection and physical characteristics of seeds including: cluster length, ‌ number of fruits per cluster, fruit length, fruit width, fruit weight, grain weight and seedlessness percentage in each altitude class were evaluated. Analysis of variance and comparison of means were performed using F test, Duncan multiple comparison test and Kruskal-Wallis test, respectively.s

Structural properties of forest stand affect forest soil and soil characteristics. The purpose of this study is to investigate the changing of soil physical and chemical properties under different forest structure in Kurdistan province. At first, four one-hectare (with dimensions of 100 × 100 m) plots were selected in Baneh (two stands), Marivan and Sarvabad (one stand) and structural characteristics of stands were determined. Seven soil samples were taken from a depth of 0-10 cm in each site (a total of 28 soil samples) and the physical and chemical were measured. Results of one-way analysis of variance test show a significant difference in most of the physical and chemical properties of soil (except nitrogen and electrical conductivity) in the four stands. The results showed that forest stand with young coppice structure (with higher canopy percentage ) increased organic carbon (3.15%), absorbable potassium (5.37 mg/kg), absorbable phosphorus (10.5 mg/kg), electrical conductivity (483 d s m-1) and soil moisture content (9.95%) in compere of another site. The results of principal component analysis showed that the first and second components account for 90.27% of site changes and the first component includes electrical conductivity and potassium variables and the second component includes absorbable phosphorus, organic carbon and weight moisture. Considering the positive effect of forest stand with young coppice structure (with higher canopy percentage and higher tree density) on the forest soil, it is recommended to regenerate and develop the forest in coppice stands with a density of less than 150 tree in hectare.

Densification of biomass materials such as briquette improves the management properties of materials for transportation, storage, and so on. This study aimed to determine the optimal conditions of the briquette production process using a hydraulic press from the combination of bagasse and walnut shell using response surface methodology. The effects of independent variables including bagasse particle size (PS), process temperature (PT), bagasse moisture content (MC), and the composition ratio percentage of the walnut shell to bagasse (CR) were evaluated at three levels on the response variables of the density and tensile strength. The calorific value of the briquette was determined through validated linear and nonlinear equations of the high heat value using the proximate analysis of volatiles, fixed carbon, and ash. The results showed that by decreasing the moisture content of bagasse particles, the density and tensile strength of the briquette increased. Adding walnut shell particles to the briquette produced with the size of fine particles reduces tensile strength. The briquette production significantly reduced the percentage of volatile materials relative to their biomass and increased the percentage of fixed carbon. The calorific value of the raw material sample relative to the briquette produced increased from 16 to 22 MJ/kg. The optimal values of the density and tensile strength of briquettes were equal to 867.847 kg/m3 and 1.356 MPa, respectively at the CR of 5%, PS less than 1.18 mm, MC content of 7%, and PT of 360 °C. At this condition, the calorific value of 22 MJ/kg was obtained.

This study aimed to predict water absorption (WA) and swelling of heat-treated silver fir wood (Abies alba) at 180, 200, and 220 oC by simple regression, multiple linear regression, as well as multiple non-linear regression models. ∆E (total color difference), ∆L (lightness difference), contact angle (CA), and mass loss (ML) were used as predictors. The results showed that WA, volumetric swelling (SV), swelling in longitudinal, radial, and tangential directions (SL, SR, and ST) decreased with the increase of heat-treatment temperature, but the values of ∆E, ∆L, CA, and ML increased. The lowest mean absolute percentage error (MAPE) for the prediction of WA with the simple regression models was related to the Cubic model based on ML equal to 6.22. The lowest MAPE for the prediction of SV, SR, and ST were related to the Cubic model based on ML equal to 3.01, 3.55, and 4.2, respectively. The MAPE values for the prediction of WA, ST, SR, and SV by the multiple linear regression model were 6.11, 3.9, 3.89, and 2.7, respectively. Their corresponding values for the non-linear regression model were 5.76, 3.86, 3.6, and 2.61, respectively. Since MAPE below 10% is satisfactory for predicting, the studied models have predicted WA and their corresponding swelling of heat-treated wood with acceptable accuracy. The best time and cost-efficient regression model is the simple model, and the best predictor in terms of time, cost, and the ability to measure in line is the color index.