مجله پژوهش و توسعه جنگل
سال ششم شماره 3 (پاییز 1399)

In order to strengthen and stabilize the soil masses in the range of soil till optimum, it should be used appropriate stabilization methods. The purpose of this study was to evaluate the effect of excess ash as an additive to soil and improve soil properties. To do this, 15 soil samples from the forest road fill slope were randomly selected combined with 3, 6, 9 and 12 weight percent logging residual ash. In order to investigate the effect of addition of stabilizing agents on the chemical and mechanical parameters of soil in the studied area, the experiments Atterberg limits, California bearing ratio, moisture as well as acidity, electrical conductivity, phosphorus, nitrogen, organic matter and carbon were carried out on control and treated soil samples. Data were analyzed using one-way ANOVA and Tukey tests were used to compare the averages. The results of the experiment show that the addition of logging residual ash increased plastic limit and California bearing ratio and reduced liquid limit and plasticity index. Also, the results of one-way ANOVA showed that the mean difference in moisture, acidity and nitrogen were not significant (P>5%) while electrical conductivity, phosphorus, potassium, organic matter and carbon showed significant differences.

In this research, which was done in Ramsar forests in Mazandaran province, the forest increment was estimated using artificial neural network and compared with the actual increment of the forest which was directly measured in 20 sample plots of 1 hectare in 2002 and 2012. The annual volume growth of beech was 4.52 and 4.35 m3 in hectare for direct inventory and estimation by artificial neural networks. Then regression analysis was performed to compare the results, stepwise, and the best models were selected. After selecting the best model for forecasting growth, the sensitivity analysis of inputs was investigated.The results showed that the neural network with relatively good accuracy can estimate the annual growth and cutting. The value of R2, RMSE and MAE were 0.75, 17 and 13.6 (for 20 sample plot of one hectare) respectively in the multi-layer perceptron network. Results also showed that the MLP neural network had the highest accuracy in predicting and estimation. In the analysis of multiple linear regression, the coefficients of detection were 0.610 and 0.679, respectively, and RMSE was 1.5 and 1.42, respectively, for the first and second models respectively. The volume at the beginning of the period and the diameter at breast height had the greatest impact on the amount of wood produced. Comparison of the models showed the use of neural network can predict the growth rate with proper accuracy.

This study was conducted to investigate the effect of fire on some soil chemical properties in Northwestern oak forests of Iran. The study area was selected 30 km from Sardasht city in West Azerbaijan province which was burnt in September of 2017. The control or unburned area was selected with the same conditions adjacent to the burn area. After surveying forest conditions in each area, 9 plots, each with an area of 500 m2 and a total of 18 plots were sampled using systematic random method and 100 × 100 m grids. Soil samples were collected at the center of each plot at a depth of 0-10 cm at three times: 1 - immediately after the fire 2 - three months after the fire and 3 - six months after the fire. The pH, EC, K, P, OC, Mg, N factors were measured. The results showed that the soil elements in the burned area were slightly higher than the unburned soils but these increases were not statistically significant. The results of repeated measures analysis showed that the effect of time on the acidity (pH), calcium and magnesium in the burned and unburned area was statistically significant. The largest change in the value of the three above mentioned variables was observed three months after the fire. Overall, the low intensity of surface fire in the area did not have a significant effect on soil chemical properties, so that six months after the fire, most of the elements returned to their pre-existing levels.

The aim of this study was to evaluate the performance of local users on pollarded oak stands. For this purpose, biometric indices (total height, trunk height, crown height, crown area and crown height to total height ratio) of Quercus libani Oliv. trees were used. Three pollarded stands with similar physiographic conditions and the same pollarded age (four years after pollarding) under the traditional management of three different local users were selected. In the selected pollarded stands, using 100% inventory, collar diameter for all trees (collar diameter ≥ 5 cm) were measured. For the Quercus libani trees, in addition to collar diameter, total height, trunk height and two small and large crown diameters in the two perpendicular directions were measured. The results indicate a significant difference in terms of biometric indices (i.e. total height, crown height, crown area and crown height to total height ratio), which confirms the different behavior of local foresters in performing pollarding and the possibility of using these biometric indices to evaluate the performance of local users.

The aim of this study was to investigate the effect of environmental factors and stand properties on changes of humus forms in the managed and old growth forest of Gorgan. First we superimposed geological, soil, topography and tree type maps to producing homogeneous units. In each unit, three sample plots (20 × 20 meters) were selected and five humus profiles were described in each plot. Main and secondary humus forms were identified based on new European classification. Environmental factors and stand characteristics were investigated in each sample as factors influencing the changes in the humus form. Kruskal-Wallis test and random forest algorithm were used based on the Gini index for analysis. Three main humus forms and eleven secondary forms were identified in the research area, so that the main humus of the MULL (49%) and the secondary humus of the Oligomul (26%) were the most abundant humus forms. There was a significant difference between the main (p<0.01) and secondary (p<0.001) humus forms between the managed and old growth forest. The effect of most environmental variables and stand characteristics were significant on the changes of humus forms. The effective important variables in the main and secondary humus forms classification were thickness of H horizon, altitude from sea level, geographic direction and tree basal area.

The aim of this research is to determine the optimal stock level in Hyrcanian forest of Iran. In this study, a goal programming techniques was used in order to estimate the optimal stock level of different tree species considering economics, environmental and social issues. Multiple objectives in the process of decision making were considered to maximize the net present value, carbon sequestration and labor. Regression analysis was used to develop a forest growth model. In addition, an allometric function was used to determine the amount of carbon sequestration. Expected mean price is estimated using wood price and variable harvesting costs to determine the net present value of forest harvesting. The fuzzy analytic hierarchy process is applied to determine the weights of goals using questionnaires filled by experts in order to determine the optimal stock level. Results showed that the optimal volumes were 256.2 m3⋅ha-1, 61.2 m3⋅ha-1, 38.8 m3⋅ha-1, 20.4 m3⋅ha-1 for, and 20.4 m3⋅ha-1 for beech, hornbeam, oak, alder and the other species, respectively. Furthermore, the results indicated that the total optimal volume is 397.005 m3⋅ha-1.

Monitoring of land use changes in forest areas provides acceptable information for better planning and management on forest resources. In this study, to assess the changes of the forest cover in the central part of Boyer-Ahmad County in Kohgiluyeh and Boyer-Ahmad Province in southwest of Iran, satellite imageries of two different Landsat time series including Landsat 5, TM satellite data (30.6.1987), and Landsat 8, OLI-TIRS data (23.7.2013) were used. Supervised classification was carried out by applying the Maximum Likelihood Algorithm and LMM model (Matrix Multiplication pictures). Moreover, Logistic regression and Geomod model were used to provide validation map and prediction of forest cover changes in 2039, respectively. Land cover maps achieved from the study area showed that there is a reduction of about 8395 hectares in the forest area during the past 26 years (1987-2013). Moreover, it is predicted that the forest area will decrease around 9938 hectares during the coming 26 years. The results showed that the kappa coefficient obtained from the supervised classification on the satellite imageries in 1987 and 2013 were 0.89 and 0.88, respectively. Moreover, the results of Logistic regression with pseudo R2 and ROC were 0.24 and 0.73, respectively, which indicate that the obtained model is relatively adapted to the real changes and there is an appropriate ability for the model to estimate the forest changes in the last 26 years. Results of simulation of the forest cover changes in 2013 reveal that the Geomod model is a good tool for forecasting the forest cover changes. The accuracy and precision of the obtained forest cover maps is about 90 percent.

This study aimed to investigate the antioxidant enzyme activities such as catalase, superoxide dismutase, ascorbate peroxidase in Calotrope seedlings (Calotropis procera Ait) inoculated with mycorrhizal and Rhizobacterial microorganisms affected by drought stress under greenhouse conditions during a six-month period. Experiment in three inoculation levels (non-inoculated or control, Rhizophagus irregularis mycorrhizal fungi and Pseudomonas putida Rhizobacterial) and with three levels of drought durations (3, 6, and 12 days irrigation) in a completely randomized design with three replications was conducted. Results revealed that inoculation of mycorrhiza and Pseudomonas Rhizobacterial under drought stress significantly increased the activity of antioxidant enzymes. Maximum activity of catalase (1.57 units of enzyme per mg of fresh weight), superoxide dismutase (17.43 units of enzyme per mg of fresh weight) and ascorbate peroxidase (4.56 units of enzyme per mg of fresh weight) in mycorrhizal seedlings under drought stress for 12 days and also highest amount of peroxidase activity in mycorrhizal (11.96 units of enzyme per mg of fresh weight) and Rhizobacterial (12.9 units of enzyme per mg of fresh weight) seedlings under drought conditions for 12 days were observed.

This study was conducted with the aim of classifying the Box tree forests of the plant communities in Bandar Gaz Golestan. For this purpose, Vegetation releves, 97 numbers, were made at peak vegetation cover by systematic-selective method in 200 meter grid dimensions with an area of 400 square meters by using Braun-Blanquet and consideration indicator stands concept. In each releves, all vascular plant species were recorded, and their percentage cover was visually assessed using a modification of the ordinal van der Maarel cover-abundance scale. The classification of plant communities was done using the combined results of two modified TWINSPAN methods and a Braun-Blanquet table synthesis method. Determination of diagnostic types was also done using the qualitative index of correlation coefficient. The results showed that in the area of the region, there are five plant communities in the form of two communities: Danae racemocii Buxetum hyrcanae and Parrotia persicae-Buxetum hyrcany and five subspecies of Quercos castaneifolia, Acer cappadocicum, Cornus australis, Ficus carica and Zelkova carpinifolia. The results of this study, while introducing Box tree Syntaxons in the eastern part of Hyrcany, indicate the high sociality of the Box tree species in the formation of distinct herbaceous communities with high denominability of the forests due to the absence of herbaceous species in the foraminous.

Joint-point method is one of the distance sampling methods for forest inventory. For estimation of tree density with joint-point sampling method two estimator suggested by Batcheler and also Engeman et al. that biased in nonrandom spatial pattern. Aim of this study was presentation a new unbiased and most efficiency estimator for this method. Forty-four sample size for each of six sampling methods: Circle plot (10ar as true value), Nearest individual method, nearest neighbor method, Compound method, second nearest neighbor method and Joint-point method in forests of Sorkheh dizeh Dalahoo of Kermanshah province with systematic random design (100m*100m) carried out. After that trees density of forest stand calculated with 10 estimators of above methods and new estimator. Then calculated density with new estimator compared with Batcheler and Engeman et al. estimators and other estimators in different spatial patterns (regular, random and aggregate) by precision and accuracy criteria. The results showed that this new estimator was not only most efficient than Batcheler and Engeman et al. estimators but also was best than other estimators.

Process of natural regeneration in uneven-aged stands is one of basic issues for sustainability in close to nature silviculture approach. The present research started form 2009 in four intact oriental beech stands of the Hyrcanian forests. Twelve, one ha sample plots have been established in three development stages containing five micro sample plots of 4 m2. Three gap sizes (small, medium and large) with five micro sample plots of 4 m2 have been selected within the development stages and characteristics of saplings have been studied. Relative light intensity (RLI) and leaf area index (LAI) have been studied as well. Results showed that the stands in the initial and optimal stages were pure, while decay stage was mixed. The least RLI was observed in the optimal stage and small sized gap while the highest amount of RLI was in the decay stage and large gap. The lowest amount of LAI was calculated in the optimal stage and small gap size. The maximum mean height increment was measured in the initial stage and small gap, maximum length of uppermost internode and annual shoot in optimal stage and large gap and the widest crown width was calculated in the initial stage and small gap. The proportion of saplings with favored quality was highest in the optimal stage and medium gap size while the highest proportion of twig and broom shaped saplings was observed in the large gaps. Overall, small and large gaps can negatively affect the saplings, whereas medium sized gap creates better condition for saplings.