فصلنامه تحقیقات جنگل و صنوبر ایران
سال بیست و پنجم شماره 4 (پیاپی 70، زمستان 1396)

The objectives of study were to compare different types of wood loss including breakage, split, slab, and high stump and also to investigate cut components such as, height and depth of undercut and back cut, notch, and width of hinge wood between the two groups of workers. Parcels no. 138 and 139 in Asalem Nav series 1 were chosen as the study area. 150 felled trees by workers paid by piece and day work method were selected randomly. The mean stump loss between the two groups was compared by Independent- Sample T- test and the comparison between the size of each components of felling and the standard felling was made by Paired Sample T-test. There was a significant difference between felling values in different groups compared with standard values except the depth of back cut in the second group (33.41 cm) and the width of hinge wood in the first group (6.78 cm). The average high stump loss for the four groups was 0.035, 0.0355, 0.0498, and 0.0438 m3, respectively. The average loss per felled tree among the four groups was 0.2915, 0.2286, 0.3775 and 0.4637 m3, respectively. There was a significant difference between mean value losses of wood in the four groups; the day work paid group had fewer losses compared the piece work paid group. The largest volume of loss in all groups belonged to breakage damage. Regarding the price of different products fabricated from the wood cut, results showed that the greatest decrease in price belonged to the groups paid by piece work contract.

Now a day, due to applying the close to nature forestry method to manage the Hyrcanian forests and harvest distribution in this method, reducing damage to the residual stand gains more important. The aim of this study was to determine and compare the resistance of the various diameters of tree species against scars or created during logging operation considering to the size, intensity and different locations as well as to study the change in the wound (healing and wound closure) in the species over time. The research was carried out in the Patom and Namkhaneh district in the Kheyrud Forest. The results showed that there were significant differences among scar healing in the tree species. By increasing the diameter of the trees, the healing rate was significantly reduced, while by increasing the size of the wound (the primary area of the wound), scar healing rate was significantly decreased. Also, by increasing the scar height along the bole, the rate of wound healing has been changed significantly. By the increasing severity of the wound, healing rate was significantly reduced. The results showed that scar age has significant effect on the healing rate, but traffic intensity hasn’t significant effect on wound healing rate. Tree position along the skid trail has positive effects on the amount of residual damage trees. Due to the fact that wounds are made in one meter height of the trunk, which is the most valuable part of the tree, trying to control the damage of trees is essential in the ground skidding operations.

Effects of anthropogenic disturbances through livestock grazing, wood harvesting, and direct utilization by local people plus spatial heterogeneity on the regeneration of forest tree species and forest health have been recognized worldwide. In this research, effects of disturbances and site features (Aspect, slope percent, altitude, and soil) were investigated on tree species regeneration in Khyrud forest-Nowshahr, north of Iran. Indicators pertaining to saplings, large sapling and trees were measured in 100 plots, 10 m2 each, for disturbance and spatial constructs of Structural Equation Modeling- Partial Least Squares method. Results showed disturbance has a significant (α = 0.01) effect on regeneration. Effects of sapling on large sapling and large sapling on tree constructs were significant (α = 0.01), too. The moderating effect of spatial construct on disturbance to sapling path (α = 0.01) and disturbance to large sapling path (α = 0.05) was significant. We conclude that disturbance and spatial attributes have high influence on sapling and large sapling in the study area, respectively which affect trees indirectly.

Topography is recognized as one of the effective drivers in spatial pattern of trees scattered on steep slopes. Topography influences spatial distribution of trees by changes in light availability, soil moisture and microclimate. This study was aimed to analyze spatial pattern of Montpellier maple (Acer monspessulanum L.) located on steep slopes in Zagros vegetation zone. For this purpose, a 200 m × 200 m plot was selected in Montpellier maple site close to Firoozabad, Fars province, with the minimum and maximum altitude of 1470 and 1540 meter above sea level, respectively. The spatial location of 288 maple trees with dbh ≥ 5 cm were registered by Leica TS06. Spatial pattern of trees was then investigated by structurally different summary statistics (pair correlation function, nearest neighbour distribution function, spherical contact distribution function). Spatial pattern analysis of the trees regardless of slope caused biased results. While the spatial pattern of maple trees in the study plot with slope of 35% was significantly clumped up to 29 m distance and the largest distance to nearest neighbour was 16.3 m. The largest empty space among the trees was observed at 40.8 m spatial scale. In general, it was concluded that spatial pattern analysis of Montpellier maples scattered on steep slopes should be investigated by summary statistics that consider distances among trees on slope instead of their distances on plain surface.

Canopy gaps play an important role in the dynamics of temperate forests. The present study aimed to evaluate the effect of canopy gaps area on soil biochemical activities in Khanikan region of Nowshahr. In this study, 32 canopy gaps with small (195-205 m2), medium (397-406 m2), large (593-604 m2) and very large (792-807 m2) areas, 8 replications for each, were considered. Five points were selected within each canopy gap; soil samples were taken and mixed due to transferring to laboratory for analysis of physico-chemical, biological and biochemical properties. According to findings, whole of soil physico-chemical (except for silt content) and biological properties were significantly affected by different canopy gaps areas. The highest urease activity was found under medium and small (22.97 and 22.54 µg NH4–N g−1 2 h−1) canopy gap areas, respectively. Medium gaps showed the most values of acid phosphatase (633.75 µg PNP g−1 h−1), arylsulfatase (153.38 µg PNP g−1 h−1) and invertase (273.25 µg Glucose g−1 3 h−1). Greater amounts of dissolved organic carbon (94.73 mg/kg) and dissolved organic nitrogen (34.66 mg/kg) were found under very large and medium canopy gap areas, respectively. Creation of very large canopy gaps was due to increasing of fulvic (454.62 mg/100g) and humic (888.88 mg/100g) acids in the studied forest ecosystem. As a general conclusion, based on forest sustainable management, it is proposed to avoiding of large and very large canopy gaps creation.

Oriental beech (Fagus orientalis Lipsky) is one of the most valuable tree species that covers 17.6% of the area and make up 30% of the stand volume in the Hyrcanian forests. This study aimed to update the form factor and to improve the volume table of this species. For this purpose, we applied random sampling method to collect field data from 150 beech trees in different diameter at breast height (D.B.H) classes (30-135 cm) based on inventory and marking list of 2015-2016. The sample trees were distributed in five forest management plan area including Livan, Vatana, Kordkuy, Shamushak, and Dr. Bahramnia. In each tree, D.B.H and diameter at 0.1, 0.3, 0.5, 0.7 and 0.9 of tree height, as well as diameter at two tops of 2 m long logs were measured. Finally the tree volume, true, natural, artificial and Hohnadl form factor for each tree was computed. The results showed that true, natural, artificial, and Hohnadl form factor value were 0.503, 0.464, 0.407 and 0.454, respectively. There were significant statistical differences between the true, artificial and natural with Hohnadl form factor (α = 0.05). The difference between true and natural form factor was not significant. Also, the results showed that there was significant difference between the computed volume and the volume driven from volume table (tariff); the greatest differences between the mentioned volumes estimated was mainly in the large D.B.H classes. According to the results, we can conclude that the natural form factor can be applied to determine the beech form factor.

The aim of this study was identification of ecosystem units in Arasbaran forests and determination of effective environmental factors and biodiversity indices on their distribution. For this purpose, 130 circular plots with an area of ​​314 m2 were examined in a random - systematic design with 300 × 300 m dimensions. Tree and shrub species in the original sample plots were measured. Species, canopy cover and vegetation cover were considered as basic measurement criteria. Herbaceous species were studied in micro sample plots, each 3.14 m2. Six ecological groups were classified using two-way analysis of indicator species (TWINSPAN) and comparative analysis (RA) methods. Analysis of groups was performed by applying analysis of variance and discriminant analysis based on topographic and biodiversity index. The discriminative analysis showed that altitude and gradient-direction as two topography variable, and the Margalef richness index, evenness indices of Smith - Wilson, Sheldon and Simpson, and heterogeneity (diversity) indices of Simpson, Hill (N1) and Shannon-Wiener were the five important indices which were significant (α = 0.01) which confirmed the accuracy of the classification at 83.8%. Therefore, it was concluded that topographical characteristics had more influence on the formation of ecosystem units than plant biodiversity indices. We also concluded that the ecological classification system can present a suitable prediction of environmental characteristics.

This research was carried out in Sirachal Research Station in order to identify the best method for Greek juniper (Juniperus excelsa M. B.) afforestation as one of the most important forest species in Iran. Three year-old juniper saplings were transported to Sirachal and were planted in a Split-Plot Randomized Block Design with water harvesting (in 5 treatments including using organs of native plants and shrubs at the bottom of pits, using 1×1 m plastic film at the surface of pits, using Aquasorb polymers mixed with the pits soil, semi-circular bonds and control) as main factor and shading (in 2 level of using tree sprouts as artificial shading and control) as secondary factor in 3 replication and 16 saplings per replication. Measured variables were survival, collar diameter, height, and crown area and sapling vitality at the end of growing season of 2015 and 2016. Results showed that rainwater harvesting had significant effect on survival juniper saplings for both 2014 and 2015 years and current annual increment of collar diameter. The highest value of these parameters was noticed for plastic film treatment though the highest decrease of survival from 2014 to 2015 was noticed for this treatment too. Both rainwater harvesting and shading had no significant effect on height, crown area, vitality and their changes during the studied years. Overall, results confirmed the possibility of rainfed afforestation of Greek juniper in high altitude of Southern Alborz Mountain. To achieve this goal, usage of nylon at the surface of plantation pits is recommended. There is no need to use artificial shading for planted saplings.

The aim of the present study was selection of adaptable species with proper growth and wood production and resistant to cold with the aim of wood production and cultivation in the urban green space and infertile lands of Saveh. Seedlings of Eucalyptus suggrandis ssp. Suggrandis, E. microcarpa, E. suggrandis ssp. Alipe, E. camaldulensis 41-sh, E. camaldulensis var. camaldulensis, E. rubida 166-sh, E. viminalis 168-sh, E. sargentii and E. camaldulensis 41-ch were planted in 3×3m spacing on late March 2010 in three replications with 25 seedlings based on Randomized Complete Block design (RCB). Also, some physic-chemical properties of soilwere examined. Results of the data analysis showed that the maximum total height, crown diameter and trees quality were observed in E. camaldulensis 41-sh. While E. viminalis 168-sh showed maximum diameter at breast height and E. camaldulensis 41-ch the heigheststanding stock volume, volume increment and quality in compare to other species. Eucalyptus suggrandis ssp. Suggrandis, E. camaldulensis 41-sh and E. microcarpa were most resistant to cold. The maximum rate of survival was measured in E. sargentii and the lowest in E. rubida 166-sh. Total height was found to be the most important factor in extraction data variance. E. camaldulensis is recommended for wood production and E. sargentii is suggested for soil and water conservation in infertile lands of Saveh.

The aim of this study was to estimate the biomas of loblolly pine (Pinus taeda L.) using allometry method in compartment 10 of Chobar-Shaft plantation with an area of 61 ha. For this purpose, 30 circular sample plots, each 500 m2 were established. In each sample plot, the diameter of the stump, diameter at breast height (D.B.H), crown width and height of all trees were measured. Totally, 12 trees in different diameter classes were selected and cut about 10 cm above the ground. Fresh weight of different sections of trees was measured. Samples of each section were transferred to the laboratory and get dried in oven and percentage of dry weight was calculated. Modeling of biomass and independent variables was performed using non-linear regression. Normal distribution of data was assessed by Kolmogorov-Smirnov test. For accessing the best result, several models were tested. The results showed that the model of E(YT) = 0/045D2 H0/864 was the best model for estimation of total tree biomass (R2 = 0.952). Results of our research confirmed the value of allometric equations for estimating of stand biomass.

The conservation value of Coarse Woody Debris (CWD), as critical microhabitat component, in forest ecosystems led to increasingly expand interests in researches about it. The scientific CWD information had gradually considered by decision-makers for implementing forestry planning. In this study, due to evaluate qualitative and quantitative characters of CWD and its proportion to live standing trees, full callipering method was applied. Data were collected from an unmanaged parcel (parcel no. 37, Gorazbon district, Kheyrud forest) situated in southern slopes of Caspian beech forests. The study site has never been under wood exploitation. The data of CWD (middle diameter ≥ 10 cm) and stand (D.B.H ≥ 7.5 cm) were measured using full calipering method. The results of this study illustrated the average number of live standing trees, snags, and fallen trees were 357, 8, and 26 per ha, respectively. Between all species, hornbeam had the highest volume proportion both in live standing trees and CWD. One fifth of total CWD volume was accounted to sangs and stumps and about half of the total volume was exposure in low degree of decomposition. CWD volume amounted 3.5% of total yield of site study. In summary, total CWD volume is lower than optimal value considered for CWD in temperate forests which sets alarms that any removal of CWD could bring irrecoverable consequences in site study.

Cold stratification is widely used to break dormancy of ash (Fraxinus excelsior L.) seeds. In this study, two groups of seedlings produced by two treatments of ash seeds, one and two-years cold stratification of seeds were investigated with three replications in a completely randomized design in samples of one m2 per plot. Some quantitative characteristics of seedlings including collar diameter, leaf area, stem length, root length, crown height and its biomass and leaves chemical characteristics including organic carbon, nitrogen, phosphorus, potassium and relationship between carbon to nitrogen are examined. The results showed that seedlings density from the two-years old seeds (average of 157.67 seedlings per m2) was significantly higher than that of one-year treatment seeds (average of 61.67 seedlings per m2). Also significant difference between two stratification treatments was recognized for collar diameter, crown diameter, crown height, total height, root length and leaf area index; which were higher values in two years’ cold stratification treatment. Among the chemical characteristics of leaves, only potassium content showed significant difference which was higher in the two years’ cold stratification treatment. In general, we conclude that cold stratification on seed of ash for two years ensure the successful production of ash seedlings in nurseries.

Mycorrhizal symbiosis increases micro and macronutrients especially phosphorous. Ectomycorrhizal symbiosis is kind of mycorrhizal symbiosis, which occur between the roots of some forest trees and ectomycorrhiza fungi. In this symbiosis, energy transfers from plant to fungus and nutrient elements from fungus to plant. In order to study the amount of phosphorous uptake in leaves through the symbiosis of ectomycorrhizal fungi with Brant`s oak (Quercus brantii Lindl.) seedling roots, we plant one year oak seedling in hydroponic culture system (Johnson complete solution) and then inoculate these seedlings with ectomycorrhizal fungi of Inocybe rimosa (Bull.), Amanita crocea (Quél.) Singer, Boletus comptus Simonini, Tricholoma sp.According to the results, after symbiosis the structure and shape of the symbiotic roots changed into the short, thick and different shapes. Inoculum of these fungi affected significantly (α = 0.01) on phosphorous uptake by oak seedlings. Mean comparison showed that phosphorus uptake has increased 2.5 and 4.4 times in inoculum treatments than control treatment. Application of ectomycorrhizal fungi (biological fertilizer) can help tree roots by increasing water and nutrient elements uptake resulting from increasing oak seedlings survival in forest ecosystem.

Today, concern about environmental degradation and conservation is a priority. In this regard, the impact of trade on the environment is an important and growing issue in current politics. International trade affects the quality of the environment with respect to the three dimensions of scale, composition and technology. The carbon dioxide emission index is used to demonstrate environmental quality. The purpose of this study was to investigate the effects of the liberalization of the wood industry on Iran's environmental quality in relation to the 16 main wood trade partners within 1995-2015. In this study, the data panel method and the Stata software were used to estimate the model. The results of the model showed that the effect of the scale of 0.08 units and the effect of the combination of 0.427 units were overcome by the technical effect. Also, the results showed that due to the liberalization of the wood industry of Iran in relation to its wood partners, the combination of the three mentioned factors amounting to 0.424 units would reduce the quality of the environment.

Earthworm population, as a biotic factor, affects health and productivity of forest ecosystems. Earthworm density and biomass indicates biological activities and quality of soils. In order to get the benefit of earthworm ecological potential in Zagros forest management, the current biological activities as well as environmental factors impacting of this invertebrate have to be understood. This study aims at determining the density and biomass of earthworm and investigating their relationships to environmental factors including seasonal variability, soil depth and the tree canopy in Brant’s oak (Quercus brantii Lindl.) high forest of Darber area (Khoram Abad, Lorestan). Thirty two single-stem trees of Brant’s oak were sampled. Earthworm’s density and biomass were measured in spring and autumn, under and away from the canopy, using soil profile. Soil profiles were 50 cm deep and samples were taken from layers at 0-10, 10-30, and 30-50 cm depth. Means of earthworm’s density and biomass were compared using one way ANOVA and independent t-test at the 95% probability level. The results of this study showed that seasonal variation, soil layers depth and tree canopy had significant impacts on earthworm’s density and biomass. Earthworm’s density and biomass were decreased in autumn and also in spots away from tree canopy. Minimizing topsoil disturbance and expanding canopy coverage in managing Zagros forest resources could optimize the environmental conditions for earthworm biological activity, which would improve soil quality and ecosystem health.

The vegetation ordination and classification based on conservatism species can be better able to analyze the ecological relationships between vegetation and environmental factors. This study aimed to investigate changes in herb layer vegetation of Quercus brantii, Q infectoria, and Pyrus glabra forest types based on conservatism species, at different environmental factors. Tree and herb layer was surveyed using 24 main plots (500m2) and 3 sub-plots (4m2) randomly distributed in each main plots, respectively. Crown canopy, physiographic features, and some edaphic factors were measured in each main plot. Species richness and species frequency were recorded in sub-plots as an abundance index. The relation between environmental factors and herb layer dynamic were investigated by ordination (CCA, PCA & DCA) and classification (TWINSPAN) methods after determining conservatism species. Based on the results of ordination and classification, herbaceous layer in Q. brantii type was significantly different in species composition and physiographic and edaphic factors from Q. infectoria and P. glabra types. Herbaceous layer in Q. brantii type showed a positive correlation with high levels of nutrients and the effective main components were OC, N, K, sand, altitude, and saturated humidity in top soil. The Q. infectoria and P. glabra types were observed in calcareous and heavy soils low elevation with nutrients deficiency. The herbaceous layer and soil in Q. brantii type seems to be more evolved due to climax tree layer.