مجله جنگل ایران
سال نهم شماره 1 (بهار 1396)

Reducing the impact of harvesting on residual stand and regeneration is very important considering the application of close-to-nature forestry for Hyrcanian forest management and the low cutting volume distribution in this method. This research was carried out in two compartments no. 317 and 320 in Gorazbon district, Kheyrud forest, Nowshar, Iran. The objectives of this study were to determine the amount of damages on residual stand and express monetary cost of the damages in order to create incentives to better forest resources management in order to preserve these valuable resources. Considering the results of all felling areas in sample plots showed that most damages were on trees with DBH

The difference between subgrade and expected bearing capacity is compensated with pavement. Usually, due to budget constraints, local aggregate material is used for road construction and maintenance activities. Before using these materials, conducting mechanical tests is necessary, but unfortunately, these tests are neglected in forest management plans which may cause future problems for the road. In this study, mechanical tests were conducted on two source aggregate samples and the results were compared with standard values. The results showed that river gravel was better matched with standard particle size distribution but had low fine-grained particles than standard. Also the uniformity coefficient and coefficient of gradation for riverine mix represent a wide range of particle size and size distribution between D10 and D60. The results of Los Angeles tests for riverine and mine mix were 29.38 and 23.09%, respectively and broken face content was for riverine and mine mix was 94.73 and 63.26% respectively. The results showed that abrasion and broken face content were in the standard range but maximum dry density and CBR were lower than standard. Regarding available budget, some modifications like particle distribution modification or stabilization could resolve the disadvantages of the aggregate. If improvement measurements are neglected, the consequences and damages to the road will be expected, a phenomenon that many roads have due to lack of knowledge about the properties of used aggregate material.

Leaf area index (LAI) is an important feature controlling many forest ecological processes like gaseous exchanges between the atmosphere and forests, photosynthesis, evapotranspiration, water and carbon cycles. The aim of this study was to evaluate Landsat-8 OLI data to estimate LAI of forests in Zagros forests in Marivan region. To determine the relationship between LAI and OLI data, 60 sample plots were defined with a dimension of 45 × 45 m. The LAI value within each ground sample plot was determined using hemispherical photography and Gap Light Analyzer software. Suitable enhancement techniques such as vegetation indices, Principle Component Analysis (PCA), Tasseled Cap transformation and fusion were performed. The spectral values of corresponding plots were also extracted. Based on correlation analysis and contrary to expectations, negative correlation was observed between LAI, which represents the amount of greenness, and reflections in the infrared band. This could be due to the accumulation of dust on the leaves. The relationship between the spectral values and ground LAI were analyzed using stepwise multiple regression with 75% of the samples. Validation of resulted statistical models using the rest of control plots (25%) showed that the linear models are more efficient. The simple linear model of LAI and SR vegetation index (R2=0.682, RMSE% =22.6% and Bias% =-1.83) and the multiple regression model of NDVI, SR and SAVI (R2=0.722, RMSE % =20% and Bias% =-0.04) were the best ones for estimating the LAI from satellite data. Further complementary studies for determining the amount of LAI underestimation by hemispherical photography, capabilities of other remote sensing data and analysis methods are suggested to enhance this approach to estimate LAI.

Earthworm biomass is one of the most important quantitative indices of forests soil. Estimating the earthworm biomass in forest soils is often difficult due to changes in soil properties. This study aims at comparing the performance of multiple linear regression and regression tree models in estimating the earthworm biomass in different forest conditions. Earthworm biomass was sampled in 40 forest gaps and adjacent virgin forest. They were then separated from soil using hand-sorting method and weighted in 0.01 gr precision in compartment 32 Shastkolate forest. Physical and chemical soil properties were analyzed by using standard laboratory methods. The best fitted models were specified in multiple linear regression and regression tree models for estimating the earthworm biomass. The fitted models were then validated by using Mean Error (ME), Root Mean Square Error (RMSE) and Relative Error (RE) measures. Soil bulk density and total nitrogen explained 24% of total earthworm biomass variances in virgin forest while canopy area solely explained 66% of total variances in canopy gap. Multiple linear regression models overestimated the earthworm biomass while regression tree model underestimated the biomass in virgin forest but it was precise estimator in canopy gap. According to the results and due to heterogeneity in forest environment, it is recommended the research is done hierarchically for finding the important and effective variables (gap area and soil potassium in the current study) and after the site stratification based on these variables, the relationship between independent and dependent variables is studied.

Interaction between ecological and social functions of Zagros forest and traditional management reveals the importance of preemptive measures in spite of rapid socio-economic changes and consequences. Due to possible consequences (e.g. abandonment of forests and land-use change) of disruption of the interaction between people and forest, it is crucial to plan possible futures among socio-economic evolution. The main objective of this study was to structure forest management scenarios against future changes and to explain the state of traditional management in this context. The study was carried out in Armardeh forest, Baneh city, western Iran using foresight framework. In order to meet the objective a chronicle review of socio-economic situation is necessary. This study helps to distinguish the trajectory of social changes and their driving forces in relation to forest ecosystems. Thus trend of socio-economic changes was studied from 2003 to 2012 using literature review, face to face interviews and questionnaire. Weighted ranks of criteria and indicator which are effective on local livelihoods dependency on forest products were computed by using analytic hierarchy process (AHP) by participating 18 experts. Foresights were carried out with principles of Delphi method by collecting data from expert’s brainstorm and scoring. Results indicated socio-economic changes in the studied period including migration to the city, severe livestock reduction, constant trend of life expenses, reducing fuel costs, inconsiderable fluctuations of revenues, lack of social welfare and insignificant improvement of quality of life. Referring to expert’s assessment, socio-economic situation, service availability and communication are main criteria affecting the local livelihood system, respectively. Regarding to livelihood dependency on the forest resources, the Delphi analysis resulted in three management scenarios for 2023-time horizon in accordance with the vision of the Islamic Republic of Iran including (1) Business as usual, (2) Improvement of forests (favorable scenario) regarding to possibility, the scenarios were elaborated into feasible and impossible scenarios, and (3) Forest degradation (unfavorable scenario). Finally, Expert’s consensus indicated that forest degradation scenario, improvement (feasible), business as usual and improvement (impossible) have the most probabilities to happen, respectively.

Indigenous knowledge is an accumulated knowledge, skills and techniques of a specific communities derived from the direct involvement with the given environment. This study aimed to evaluate the knowledge of local communities on the use of forest trees in Arasbaran forests. The study areas were villages of Kalasour, Kharil, Khoinarud, and Balan located in Kaleybar city and Vayghan village located in Khoda-afrin city. The study was conducted by using ethnography methods and data was collected using semi-structured and un-structured interviews and participatory observation techniques. The results showed that the local knowledge in relation to the use of various parts of the forest trees was categorized in five types including fuel, fodder, medicinal, instruments, and construction materials. This knowledge used for making agricultural, animal husbandry and household instruments facilitated the villagers’ subsistence. The local people use 20 woody species for all categories and 8 woody species for medicinal uses. Rosaceae family and oak species have the highest uses in the communities. The knowledge available for mentioned practices are rich and diverse which is due to the availability of alternative sources for some applications and also the level of easy access to the different kinds of trees for different uses.

The spatial pattern of trees is one of the structural characteristics of forest stands that affects the efficiency of sampling methods. This study aimed at investigating the effect of spatial distribution of trees on the efficiency of distance and plot sampling methods. For this purpose, a dispersed Persian oak stand in Kohgilouye-Boyerahmad province (47 ha) and a clumped wild pistachio stand in Fars province (45 ha) were selected. Six distance and six plot sampling methods were applied on a 100 m × 100 m grid in the stands to estimate the density and canopy cover. The efficiency of methods was evaluated by statistical comparison of the results with true values, accuracy criterion, and root mean square error percent. The true density and canopy cover percent of wild pistachio and Persian oak stands were 19.4 trees ha-1 and 5.1% and 22.3 trees ha-1 and 17.1%, respectively. The results showed that between distance sampling methods, nearest individual (density: 19.5 trees ha-1, canopy cover: 5.2%) and nearest neighbour (density: 20.1 trees ha-1, canopy cover: 4.9%) methods in wild pistachio stand and line intersect method (density: 21.0 trees ha-1, canopy cover: 17.3%) in Persian oak stand were efficient. Moreover, all plot sampling methods were efficient in both stands (except square method). In general, the results showed that in contrast to plot sampling methods, the spatial distribution of trees influences significantly the accuracy and precision of distance sampling methods.

This study was performed in order to investigate the changes in vegetation in compartment No.317 (managed forest) and No.318 (control forest) of Jamand district of Golband forest in Nowshar, Mazandaran. The aim of this study is to compare the direct gradient analysis to express the basic structure of environmental data. For this purpose, random-systematic sampling method with regular grid of 100×200 m was used to locate the sampling plots. The plot size was 400 m2 considering to tree and shrub species and in the center of each main plot, one 100 m2 subplot was laid out for herb species. The cover percentage of each plant species was estimated by using Braun-Blanquet scale. The performance of two direct ordination techniques (CCA, RDA) were evaluated with different criteria like length of gradient, Kaiser-Guttman, eigenvalues greater than 0.4 and Procrustean analysis. CANCOO 4.52 and R software were used. Result of Procrustean analysis showed that the correlation between ordination methods were different. According to the length of gradient criteria, linear modal is proper and CCA and RDA analysis cover Guttman-Kaiser criterion with two axis. None of the analysis has more than 0.4 eigenvalue. Percentage of eigenvalue in Redundancy Analysis is more than Canonical Correspondence Analysis. Regarding to Jamand districtdataset, due to the linear structure of Redundancy Analysis, this analysis is a proper choice.

Despite the expense of construction and maintenance, forest roads are still essential to provide land accessibility and management. Quality of roads depends largely on the pavement conditions. The heavy machines directly induce stress on pavement as first layer of a road. The current study aims at investigating the equivalent axle load, the devastation wrought by the axis to the devastation wrought by the standard axis (8.16 tons), on pavement deterioration. To develop the equivalent axle load model, 50 km of forest roads, under management of Wood and Paper Company, was selected with respect to the trucks and cars and critical values and growth rates of pavement failures were identified using the log of changes failure to the equivalent axial load. The results showed that highest proportion of failure involves trucks 15 tons (growth rate 10.2), nine-ton trucks, Nissan truck and cars with the values of 5.77, 1.8, 0.64 and 0.45 respectively. According to the obtained results, less equivalent axle load vehicles with lower the volume of timber and wood out of the forest with enough time should be utilized.

Studying the effect of fire on hydrological properties, soil and surface features is important and essential to develop the methods preventing soil erosion for sustainable management of lands and water resources. In compartments within the study area, 15 burned sites and 15 unburned sites, in five sub-land units, hydrological properties, soil characteristics, water repellency and the amount of erosion were determined. Also, the status of soil erosion was evaluated using BLM method. The results of analysis of variance showed that total erosion, infiltration rate and water repellency had significant differences in burned and unburned sites. Only infiltration rate showed significant differences among sub-land units. The reversibility time for soil porosity and total erosion to conditions before the fire was about four to five years. The time reversibility for actual and potential water repellencies were also two to four and four to six years, respectively. The results also showed that canopy cover percentage, number of trees in hectare, height of tress, and soil porosity were the best variables to estimate the total erosion in study area.