kiomars sefidi

Investigating forest structure is an important and necessary topic, especially in line with the goals of close-to-nature silviculture. This research aimed to quantitatively analyze the complexity of stand structure during the transformational phase of understory formation in the oriental beech (Fagus orientalis Lipsky) forests of Kheyrud, Nowshahr. After field inspections, three one-hectare sample plots in the transformational phase of understory formation were selected, and a full inventory of all stand parameters, including tree diameter at breast height, natural regeneration, size and distribution of gaps, and deadwood, was carried out. To analyze the structural complexity in forest stands, the structure complexity indices, Cox coefficient, coefficient of variation, and Gini coefficient of tree diameter were used. According to the research results, in this evolutionary phase, the highest frequency is in small diameter classes, while the lowest frequency is in large trees. The distribution curve of trees forms a decreasing exponential with a steep slope in small diameter classes. The average deadwood volume was 30 m³, and the average gap factor of crown coverage was 6.4%. Additionally, the mean Gini coefficient and diameter change coefficient were 0.7 and 6, respectively. These values, along with the Cox coefficient, indicate optimal complexity in the stand structure during this phase. In the understory, the average abundance was 306 stems per hectare, with beech being the most abundant species. Based on these results, to maintain heterogeneity in the managed forests while preserving large trees in the stand, it is suggested to implement operations to increase the complexity of the forest stand structure and perform thinning from below.

Rangeland plants undergo continuous changes due to various disturbances, with fire being a significant environmental factor impacting plant communities. In many rangelands, the frequency and extent of fires are increasing, altering the composition and structure of vegetation communities in fire-prone environments. However, limited studies have focused on the effects of fire on the quantitative analysis of shrub plant stands in rangelands, hindering our understanding of fire's impact on structural changes in these plants. This study aimed to analyze the quantitative structural changes of Astragalus microcephalus Willd. over an 8-year period following a fire.

One control area and eight fire-affected areas, each covering one hectare and sharing similar environmental conditions and plant communities, were selected. Vegetation sampling was conducted along six 30-meter transects, with 24 points spaced 5 meters apart selected using a systematic-random method. Structural characteristics of the stands were measured by completely harvesting all shrub plant bases using the distance method. Spatial distribution patterns were investigated using Johnson and Zimer's indices, C index, Hopkins, Eberhart, uniform angle, Clark and Evans indices, Mingling index for species admixture, and Berger-Parker index for crown differentiation.

The results revealed a clustered distribution pattern in both the control area and the fire-affected area, as indicated by the Clark-Evans indices and uniformity angle. The C index and Hopkins distribution pattern indicated uniformity, which remained consistent between the control and fire-affected areas, suggesting no alteration in distribution pattern due to fire. The Johnson and Zimer's Index showed varying values for the control and fire-affected areas across different years. The Mingling index indicated weaker mixing in the fire-affected area compared to the control area. The Berger-Parker index indicated increased dominance of Astragalus microcephalus after the fire. Crown differentiation analysis revealed a greater difference in crown size between the control and fire-affected areas in the early years following the fire. One-way analysis of variance showed significant differences between different years after the fire in terms of Clark-Evans, Johnson and Zimer's, and Berger-Parker indices at a confidence level of one percent (p<0.01).

The clustered distribution pattern of Astragalus microcephalus Willd. in Khalkhal rangelands remains unchanged after 8 years following a fire, likely due to factors such as post-fire regrowth from the collar surface, seed distribution type, and reproductive strategy. Fire has led to increased dominance of Astragalus microcephalus and reduced vegetation composition. Understanding changes in structural characteristics of shrub species is crucial for assessing disturbance impacts, studying spatial distribution patterns, species dominance, and dimension differences following disturbances in mountain pastures, and planning for habitat management and restoration.

In forest management, it is essential to maintain soil performance. Forest soils control and support many forest ecosystem services and tree growth. So, maintaining soil health is critical to sustainable forest management. Forest management practices, such as converting degraded forests into man-made forests, lead to a wide range of adverse effects on soil performance and microbial communities, including negative impacts on organic carbon, nitrogen, bacterial biomass, fungal biomass, microbial biomass carbon, and fungi-to-bacteria ratio. It is possible to achieve the appropriate method of forest management by considering the biological stability of the soil. Therefore, in this stduy, it has tried to gain a better understanding of the relationship between soil biological conditions and forest management methods and their application in sustainable forest and soil management by evaluating the effect of different forestry methods on soil biological characteristics.

To influence forest management practices on soil biological properties, three study areas with different management histories in the Asalem forest, Guilan province were selected and soil sampling using a random systematic method was collected. The selected plots included 1) control, 2) a plot with a history of project implementation in the medium term of maximum 20 years under selective management and 3) a plot with a history of long-term plan implementation, which was under the management of shelterwood method for more than 50 years. There may be effects of the implementation of past plans in the forest for many years. The number of 15 samples in each plot was collected from the nearest tree to the center of the intersection of the sides of the sampling network, from a depth of 0-30 cm, and transported to the soil laboratory at a temperature of 4°C in the winter of 2016. Sampling from all plots in the forest area was done only in the pure type of beech, so in this study, the effect of the type is constant. In this study, micro-scale habitat conditions considered to investigate microbial activities were homogeneous. In this research, three parcels with an area of ​​about 132 ha were selected. In each sample, the biological characteristics of the soil, including basic respiration, stimulated respiration, microbial carbon dioxide, and the population of microorganisms were measured, and indicators of microbial benefit and metabolic benefit were calculated. Some soil characteristics including soil organic carbon, electrical conductivity (EC) and pH were also measured. The normality of the data was checked using the Kolmogorov-Smirnov test and the homogeneity of variances was checked using the Levene's test. Due to the fact that the data had a normal distribution, one-way analysis of variance test was used for totla mean comparisons, Tukey test was used to compare the average indicators in the studied parts, and the relationship between chemical indicators the Spearman correlation test was also used for soil biology. In some cases, due to the impossibility of normalization and other assumptions, the non-parametric test has been used. Statistical analysis was done using SPSS version 22 software. Excel was used to draw graphs.

The results showed that there was no significant difference between the three components in terms of organic carbon, microbial quotient, electrical conductivity, and acidity. But baseline respiration, exhaled breath, microorganism population, metabolic rate, and carbon microbial degradation showed a significant difference in the three parts. The highest basal respiration rate (46.8 mg of carbon dioxide in one day in one gram of dry soil), substrate-induced respiration (42.77 mg of carbon-dioxide in one gram of dry soil in six hours) and microorganism population (1.09 x 108 in one gram of dry soil) and carbon microbial degradation (16.5 mg of carbon in one gram of dry soil) were obtained with a patchy management method and the lowest in the selective portion. The highest metabolic quotient (1.2 mg of oxidized carbon in basic respiration per kg of dry soil per day) in selective fraction and the lowest in solitary incremental part were calculated. The soil texture is sandy-loamy in most of the three plots and loamy-sandy in some areas. EC was in the range of 0.629-3.83 dS m-1 and soil acidity was also in the range of 5-6.5 in all three plots. There was no significant difference in soil organic carbon in three plots. Correlation analysis results of forest soil biological indicators show that soil microorganisms have a significant positive correlation at the level of 1% probability with microbial biomass. In addition to soil micro-organisms, microbial biomass carbon showed a significant positive correlation with basal respiration at the 1% probability level. Basal respiration also has a significant positive correlation at the probability level of 1% with the amount of substrate-induced respiration, soil microorganisms, and microbial biomass carbon, and besides that, the organic carbon has a significant positive correlation at the probability level of 1% with soil microorganisms, microbial biomass carbon, basal respiration, and substrate-induced respiration.

The control plot has a higher quality soil compared to the plot under shelterwood management due to the least human interference (although illegal harvests have been observed in the forest, but compared to the other two plots, human interference was minimal). According to the results, it can be acknowledged that the plot under shelterwood's management has better conditions in terms of soil biological characteristics. Knowledge of the effectiveness of the biological characteristics of the soil from the application of different methods of forest silviculture and human interventions, provides the possibility of choosing suitable methods with the habitat conditions. At the same time, it will be very beneficial to determine the intensity of breeding interventions in forest stands based on the prediction of its effects. The stability of the forest does not depend only on increasing the biological quality of the soil. Hence, it is recommended to implement silviculture operations in sheltered plots and to increase the mixture of forest stand and support species with fast decomposition of litter such as horbean in selective plots.

Given the importance of measuring tree volume and the potential for selling standing trees, as well as the time-consuming and costly nature of measuring the actual volume of trees, this study aimed to find an alternative method that is more economical in terms of time and cost for predicting the standing volume of poplars (Populus deltoids) using an artificial neural network (ANN) method for harvesting and sales management. In this study, the diameters and heights of 416 randomly selected trees were measured. The tree diameters ranged from 10 to 15, 15 to 20, 20 to 25, 25 to 30, 30 to 35, 35 to 40, 40 to 45, and 45 to 50 centimeters. Their standing volumes were then predicted using both simple and multiple ANN models. In this study, diameter at breast height and height were considered predictor indices for the input data, while the standing volume of the tree was the output data. The number of input, hidden, and output layers was kept uniform at one layer. The number of hidden layer neurons was determined to be 10 using trial and error. The results showed that the simple ANN model using the diameter index yielded MAPE and R-squared values of 10.22 and 0.9785, respectively, while the model using the height index produced MAPE and R-squared values of 35.43 and 0.8004, respectively. Due to the simple model's ability to predict volume with an error of approximately 10% using the diameter predictor, the simple model with the diameter index was suggested as the best model overall, considering its ease of implementation and superior accuracy.

In order to understand the impacts of watershed management (WM) measures and their effect in solving the socio-economic and environmental problems of region, it is necessary to evaluate these measures to improve future activities in watersheds. One of the important aspects in the watershed management decision making (DM) is to consider the stakeholders participation in the planning process. On the other hand, the participation of stakeholders is not same and their opinions on the issue are varied.

Therefore, stakeholders in the mentioned watershed were divided into six main groups, and the values of the social network ratios of stakeholder groups regarding the issues discussed during face-to-face interviews were calculated.In this study, the Social Profile Ratio (SPR) method was used to determine effective stakeholder groups in decision-making and implementation of watershed management activities in the Emamkandi watershed in the northern province of Urmia in 1999. The social profile ratio, as a tool for introducing the characteristics of society and stakeholders, plays an important role in informed decision-making by the Watershed Planning Committee, and is calculated based on the scores of components including the position, power, and salience of stakeholders in relation to the issue. Therefore, stakeholders in the mentioned watershed were divided into six main groups, and the values of the social network ratios of stakeholder groups regarding the issues discussed during face-to-face interviews were calculated.

According to the results, stakeholders placed more importance on the "importance" component compared to the "position" and "power" components. The social network ratios for all stakeholders were calculated to be greater than one, indicating their agreement with the issue.

Overall, based on the results of the study, it can be said that the group of managers and experts from the Agricultural Jihad organization had the highest agreement with the issues raised compared to other groups. The use of local knowledge to create motivation for better participation had the highest social network ratio, and the lowest agreement was related to the issue of the impact of decisions made by institutions and executive organizations on improving the income of watershed residents. The results of the social network ratios for the issue of using local knowledge to create motivation for better participation in watershed management projects showed that three groups of managers, biological experts, and agricultural Jihad experts agreed with the issue raised, and the numerical value of this ratio for managers (equal to 33) indicates the agreement of most managers. In all participating groups except for managers and Agricultural Jihad experts, the social network ratios indicate their disagreement with the issue of involving watershed residents in practical watershed management decisions.

The indigenous knowledge of shepherds about the different components of the plant fuel, ways of their classification and their contribution to fire behavior helps range managers to understand fire and effective management of the rangelands. The present research aims to document the indigenous knowledge of shepherds in this regard. For this purpose, a semi-structured interview in 2020 with 17 shepherds of semi-steppe rangelands of Khalkhal in northwestern Iran was performed and data were analyzed by the note-taking method and the categorization method. Given the knowledge of shepherds, plants were categorized into three groups of carriers, retardant, and burnable. They consider the morphological traits, type and composition of vegetation, climatic factors and physiography to be effective in creation and spread of fire. Shepherds' controlled fires are carried out with the aim of removing thorny plants to increase the length of the green period of the plants, to graze more livestock, to increase the income, to destroy the old seedlings and to rejuvenate the rangeland. Uncontrolled and deliberate fires are conducted with the aim of destroying state property, protesting against fines, unhealthy competition and conflicts between individuals, which reduce the winter forage of livestock and land grabbing. The time required for the rehabilitation of the rangelands was expressed after 6-7 years after fire. Practical suggestions could be used in participatory management system (shepherds and officials from natural resources management) for controlling fuel density using different grazing systems.

In close to nature silviculture, dead trees have great importance because of their essential role in the conservation of biodiversity in forest ecosystems. In this regard, the amount (volume) of dead trees in pristine natural forests can be a guide for its maintenance in managed forests. One of the most important questions in recent years is how much dead trees can be recommended to retention in the managed natural forests. Related resources show different results for this variable. Therefore, in a meta-analysis, studies in Hyrcanian forests were collected and analyzed. This is the first meta-analysis for important structural factor in close to nature silviculture, dead tree volume, in the Hyrcanian forests.

This study includes design and search strategy, collecting articles and extracting data from them, include and exclude criteria and finally statistical analysis of extracted data. Dead tree related research was searched in national and international data base, including SID, Science Direct, Web of Science, Scopus, Google Scholar and IranDoc until May 2022. In this study, after review of several articles, data (mean, standard deviation and sample size) of 16 original studies related to the dead tree volume variable in Hyrcanian forests were collected that had 163 samples and the total area of the sample plots was 92.44 hectares. After extracting the data, Cochran's Q test and I2 index were used to evaluate the heterogeneity the studies and select the appropriate model for data analysis. To find the source of heterogeneity between studies, subgroup analysis was performed based on geographical areas (province) and tree composition. In this study, Beggs and Egger tests were used to investigate the publication bias. Data analysis was done with Comprehensive meta-analysis ver. 3.7.

The mean of dead tree volume was estimated to be 35.293 m3/h (Confidence interval 95%: 24.769 - 45.817) for Hyrcanian forests according to the significance of Cochrane Q test (p = 0.0001) and I2 index (99.735) based on the random effects model. Subgroup analysis showed that the highest dead tree volume was estimated based on a random model in the Golestan province forests as 50.520 m3/h (95% CI: 45.669 - 55.372). In this study, the publication bias test was not significant (p-value for Egger and Beggs tests was 0.28 and 0.24, respectively).

The average of dead tree volume in the Hyrcanian forests was estimated to be "average". Accordingly, the maintenance of at least 35 m3/h of dead tree in Hyrcanian-managed forests can be a guarantee for the preservation of the biological functions of these trees.

Due to rapid population growth and increasing demand for forest resources, large areas of forest have been subjected to different degrees of degradation, and this degradation is increasing at an alarming rate. Large areas of forest have been varied by various degrees of degradation, and this degradation is increasing with an alarming rate due to rapid population growth and increasing demand for forest resources. Only 15 percent of the world's forests are undegraded, 20 percent have been destroyed and 28 percent have been deforested. Forest degradation is a global phenomenon that destroy10.6 million hectares of the world's forests each year. Therefore, studies focus on the effects of forest degradation impacts on the structure and composition of forests around the world. The goal of this study was to compare the structure of oak-hornbeam stands in different degradation intensities in Arasbaran forest.

The distance method was used to calculate the structural diversity index in Arasbaran forests, using three indicators, including uniform angle, tree diameter differentiation, and mingling indices. Within the study area with the different intensity of human interventions, three one-hectare sampling areas were selected. In order to select the study points in the regular systematic way 25 *25 m grid was laid out and the nearest tree to the intersection point of gird as reference tree was selected and measured with the four nearest neighbor trees. the diameter at the breast height (DBH), distance, and angle between trees in structural groups were measured.

The results of calculating the uniform angle index showed a change in the distribution pattern of stands due to the increase in the intensity of destruction from random to clump and uniform distribution. The diameter diffrentation index of trees showed that the value of this index was the lowest (0.12) in the moderate and was the highest (0.38) in the severe degradation intensity. The results of the study of the mingling species index showed that the highest value of this index was in the low degradation intensity (0.61) and the lowest value was in the moderate degradation intensity (0.08). Statistical analysis showed a significant difference (p≤ 0.05) between these indices in all stands. Calculation of the structural diversity index also showed that the highest structural diversity was in the stands with low degradation intensity (0.5) and the stands under medium degradation intensity had the lowest amount of structural diversity index (0.14).

Planning to reduce the human interference should be prioritized considering the effects of human degradation on the structure of the Arasbaran forest.

The aim of this study was to investigate the woody and herbal frequency and species diversity in the mountain forests of northern Iran, Poudeh village of Roodsar, over time and as a result of traditional exclosure of these forests.

The study area is located in the forests of Poudeh village, Roodsar, Guilan province. According to the traditions of the region, people protected the spots of the destroyed forest areas near their hazelnut gardens for flood prevention and personal exploitation. They do this by using stones and placing shrubs on it, or using wooden stems and barbed wires. In this area, there are many of exclosure forest spots that have been protected and enclosed by the native people. Three exclosure forest spots were selected for this study. For this purpose, plots with different conservation history including low-term enclosed forest area (Less than 40 years), middle-term enclosed forest area (More than 40 years) and reference forest area were selected and the indicators of relative frequency, relative ecological importance value and species diversity were calculated.

The results showed that with increasing the duration of forest protection, the relative abundance of beech in both strata levels increased the relative abundance of hornbeam and the amount of species diversity also decreased. The highest and lowest differences in relative abundance of beech between the two strata were observed in reference forest area and low-term enclosed forest area respectively. The ratio between the abundance of beech in the upper story to the understory for low-term enclosed forest area and middle-term enclosed forest area was 1.18 and 1.24, respectively. In the control area where the highest relative abundance of beech species (80%) was recorded in the upper floor (tree), there is a moderate relationship between the two floors (r = 0.61, p <0.001) and in short-term protection, this relationship is significant (r = 0.72, p <0.001). In the middle-term enclosed forest area (more than 40 years) with increasing the relative abundance of beech in the upper story, its relative abundance in the understory also increased significantly (r = 0.88, p<0.001).

The process of species change is a complex and time-consuming process. The results show in the evolution of the stand structure in the affected areas, medium-term protection can facilitate the formation of understory. It is recommended that middle-term enclosed forest area along with silvicultural treatment be applied to formation of understory.

Grazing intensity should follow the management roles to prevent the soil compaction. Soil compaction decreases plant root penetration so that at 2 MPa the root extension and above ground biomass will stop. In this research, digital penetrometer was used to assessment the soil compaction level in Sabalan region in Ardabil province caused by livestock. Grazing intensity and distance from village were evaluated as independent variables. The results show that the grazing intensity and distance from village have significant effect on soil compaction at 1 percent of probability level. Grazing intensity at closer distance (200 m) increases the soil compaction and reduce the soil penetration. Modeling of different grazing intensities was made by ANFIS approach at MATLAB software. For assessment of models’ operation, root mean square error (RMSE) and correlation coefficient (R2) were used and the best model was determined. The results of best ANFIS model for prediction of soil compaction (RMSE=7.223 and R2=0.967) was compared with the result of regression model (RMSE=11.518 and R2=0.918). The results show that the ANFIS model had more R2 and less RMSE consequently more accuracy than the regression model.

The Arasbaran vegetation community is an important source of biodiversity and one of the biosphere reserves in the northwest of Iran, which is influenced by different climates and special importance due to variations in altitude. Since an altitude is an environmental characteristic that affects the habitat of plant species, this study aimed to investigate the ecological role of altitude on the quantitative characteristics of caucasian oak trees (Q. macranthera Fisch. & C.A.Mey. ex Hohen.) and determine the best range for the natural growth of this species in Arasbaran forests. Three oak stands were selected in three altitude ranges including low (1200-1400 m a.s.l.), middle (1400-1600 m a.s.l.) and high (1600-1800 m a.s.l.) altitude. At each altitude, three plots were sampled with one-hectare area, and the quantitative characteristics of all trees, including diameter at breast height, basal area and trees canopy diameter were measured. Normality of data was verified by the Kolmogorov-Smirnov test, and the comparison of the mean of the characteristics was done using one-way ANOVA at a probability level of 0.05 and Duncanchr('39')s test. The results showed that there was a significant difference in diameter of the trees, the height of the trees and basal area per hectare among the three altitudes, but density per hectare had a significant difference between the first and second altitudes.  In addition, the canopy coverage had no significant difference among the three altitude ranges. The middle altitude was more favorable condition stand in terms of its quantitative characteristics. Therefore, the results of this study indicated that the middle altitude (1400-1600 m a.s.l.) is a more suitable habitat for caucasian oak species in Arasbaran forests, and doing more protection of the stands in this altitude can be created a seed bank for the production of high quality seedlings and forest plantations in the region.

Forest structure is a key factor in growth, yield and how changes occur in the forest stands, and evaluating the structure of plantations can play an important role in improving afforestation and timely implementation of forestry treatments in each stand. This study aimed to evaluate structural characteristics of plantation forests in the Saib Tabrizi forest park located on Tabriz, after 25 years of planting have passed, and abandon its management.

For this purpose, after initial field surveys, three one-hectare plots were selected and based on quantitative indicators, the structure of each plot-sample was investigated. In each plot, structural characteristics of all trees (species type, diameter at breast height, tree height, canopy height, and canopy diameter) were measured and the distance method (based on nearest neighbor’s) were used to quantify stand structure. In order to study of stand structural some index including nearest neighbors distance index (density of trees), uniform angle index and Clark and Evans index (variety of location), Mingling index (species mixture), diameter and height differentiation indices (dimensional differences of trees), and complex structural diversity index (tree diversity) were used.

Based on the results, the average density of trees was 448 per hectare. In the studied sample plots, the average DBH was equaled to be 12.9 cm, the average height of the trees was 5.1 m and the average basal area was calculated to be 0.013 m2 per hectare. The highest abundance among the species belonged to the species of Pinus nigra with 50.4% and Robinia pseudoacacia 32.4%, respectively. The results of the uniform angle index showed that a cluster pattern in spatial distribution of trees, however Clark and Evans index showed a regular pattern. According to the Mingling index, the studied stands have relatively moderate mixing. The height and diameter differentiation indices showed that the dimensions of the trees had a slight difference, and have a homogeneous structure. According to complex structural diversity index, tree diversity was obtained at the low level.

In conclusion, it can be said that after nearly three decades of planting trees in this park, tree communities have maintained the homogeneity of their structure, and trees have moderate mixture. Therefore, it can be stated that the development of forest structure in the research area is slow. Hence it is recommended to increase the biological sustainability, silvicultural treatments are needed to increase mixture and heterogeneity of structure. The results of this study can provide objective justifications for the importance of consciously creating forestry strategies in the country's forestry as a missing link in the forest management.

The forest structure and stand composition are controlled by several physiographic factors, because these factors play an important role in control the physical and chemical conditions of the environment, including access to light, soil moisture, and nutrients. In this study, the physiographic characteristics indices of the study area including landform index, terrain shape index and aspect slope index and the stand structural characteristics including density, basal area, canopy coverage, and the species important value index using the Detrended Correspondence Analysis and Redundancy Analysis studied in Arasbaran forests. The results showed that the highest altitude range (1600 to 1850 m a.s.l) had the highest amount of physiographic indices value. The Redundancy Analysis showed that the LI index had a positive correlation with the first axis and TSI and AS indices had a negative relationship with it. In addition, Caucasian oak was the most important species in terms of importance value index. Detrended Correspondence Analysis between species and sampling units showed that Caucasian oak had the smallest distance with sample units and followed by hornbeam. Correlation analysis of structural characteristics and physiographic factors showed that stand density had no significant relation with physiographic factors (p≤0.05), but the correlation of the canopy coverage area with the direction of slop in the first and second altitude ranges and basal area with the landform shape in the third altitude was significant (p≤0.05). This study showed that the trees structural distribution in the study area affected by the physiographic properties. Therefore, it suggested that the effect of other environmental factors to be investigated such as soil and climate on the forest structure.

Wildfire as a natural hazard is a major problem for forest and rangeland ecosystems of the world. In the Semi-Steppe Rangelands of Ardabil Province, severe wildfires can account for the adverse impacts on the ecosystems. These fires are the result of the combination of weather conditions, dry fuels, and topography effects. The Ghasre Dagh Yeylagh fire is an example of a severe wildfire that occurred with extreme environmental conditions, which was ignited on August 16, 2015, in the Meshgin Shahr municipality. In this study, weather conditions, fuels, and topography factors that strongly affected the fire will be accurately analyzed. The fire spread and behavior data including the observed final fire perimeter and fire arrival to the northern border of the fire perimeter (firefighting point) collected during the event will be also compared with the results of fire simulation obtained by FARSITE model. The average simulation accuracy for the burned area, as measured by the Sorensen coefficient and Cohen Kappa Coefficient was 0.84. Simulation overestimation of flanking fire spread areas was expected and observed, since suppression activities that contained the fire spread were not considered in the model, due to the lake of this information. The main goal of this paper is to thoroughly study the behavior of a recent fire, to learn from it, and lessen the potential mistakes or hazardous fire-fighting operations in similar environmental conditions. Furthermore, a crucial point is to teach the fire crews not to be threatened by severe or abrupt fire behavior under extreme environmental conditions.

Evaluating the diversity and ecological value of habitat trees is an indicator for assessing biodiversity in forest ecosystems. This research was carried out to assess the ecological diversity and ecological value of microhabitats in the beech forests in the parcel 405 of Shir-Ghala, east of Guilan province. Three plots with an area 1-ha were selected, and in each plot, all live trees and standing deadwood to explore each microhabitat, and their characteristics included the diameter at breast height, tree height as well as the number and type of microhabitat trees were recorded. To analyze the status of microhabitat diversity, alpha, beta and gamma diversity indices, Margalef richness index, Shannon-Wiener, and Simpson diversity indices, and Pielou's evenness index was calculated. In total, microhabitats were identified on 87 habitat trees (equivalent to 24.2 microhabitats per 100 trees). The most and rarest form of microhabitat was woodpecker cavities and miocrosil, respectively. Trees with the holes comprised of woodpecker cavities, trunk cavities, main branch cavities, and buttress holes account for more than half of the total microhabitat (53%), and often located on live trees (68.6%) of oriental beech (77.3%). s found in the DBH class of 10-20 cm. In conclusion, it can be explained that the conservation and maintenance of habitat trees more than one meter in diameter is recommended to provide the microhabitat and preserve biodiversity in the forests.

This study was conducted to assess the effect of soil physical and chemical properties on diversity and structure of tree cover in oak forests with an area of 275 hectares in Qamyshlh city of Marivan Kordestan, Iran. For this purpose, a total of 90 samples, each 10 yards, randomly laid out on a regular gird network were selected and in the center of each plot, soil samples were taken at the depth of 0 - 30 cm. Results revealed that the average diameter of trees had a significant positive correlation with phosphorus, potassium, organic matter and carbon to nitrogen ratio in the soil. The results also showed that there is no significant relationship between the most measured soil characteristics and richness, evenness and diversity indicators. However, soil pH with Pirlo and Simpson indexes and phosphorus with Margalef index had a significant negative relationship. Correlation between the percentage of tree species and soil characteristics showed that among the studied species, Q. branti were more sensitive to changes in soil properties compared with other species. However, the analyses of ordination methods showed that there is no direct relationship between species distribution and soil properties. In addition to the soil effects, due to the proximity of the forest land to rural residential areas, it can be said that the most influential factor in shaping the composition, diversity, and structure of Qamyshlh tree species are human factors.

Biodiversity estimation is one of the key issues in the management of the forest as one of the most sustainable and complete ecosystems and trees are considered the main members of forest ecosystems. Therefore, the aim of this study was to investigate the influence of the elevation on the changes of tree species biodiversity in a part of the Arasbaran forest. For this purpose, species richness, Simpson and Smith-Wilson uniformity indices, and diversity indicators included Shannon, Simpson, N1, and N2 were calculated by using the data obtained from sampling plots in different elevation classes and measurement of various tree species. The results showed that species richness decreased with an increase in elevation but uniformity increased. Also, the Shannon and N2 indices in low elevation and the Simpson and N1 in high elevation showed the most diversity in the study area. The final results of the present study indicated that elevation is effective on a variety of indicators of diversity, richness, and uniformity and will reduce them. Therefore, this is recommended to the study of environmental factors affecting this reduction.

Colutea persica is one of important and valuable species in Kandiragh forest reserve of Khalkhal. This study aimed to determine the relationship between Growth properties of Bladder Senna with soil and physiographic factors in Kandiragh forest reserve. in three land forms (ridge, valley and slope) and in four aspects (north, south, east and west) from lower to higher distribution areas sample plots, each 500 m2, were selected. Overall, 32 sample plots were used for measuring Growth characteristics; soil characteristics were studied in 12 sample plots including soil texture (clay, silt and sand), pH, Ec, N%, OC% and Caco3%. The results showed that the distribution range of Bladder Senna varies from 1350 to 1980 m.a.s.l. In general, slopes and ridge forms with south and east-facing slopes are suitable sites for this species. The highest figures of Bladder Senna individuals including height (1.75m), crown diameter (1. 81 m) and regeneration (169.N/h) on valley form and the highest number of shoot (13/11) on slope form were measured. Soil of Bladder Senna habitats is deep to semi- shallow with pH (7.4 to 8.1), Ec (0.21 to 0.39 ds/m) and with soil texture of loam to loam- sand. The PCA analysis showed that the physical properties of soil (sand, clay and silt) and Ec have an important impact on the presence of this species. So that, the presence of Bladder Senna in the southern and eastern slopes has more correlation with silt percentage.

Assess the diversity of the understanding of ecosystem function; maintain genetic resources, checking environmental changes, and success or failure will help natural resource management programs. Over-grazing and uncontrolled usage of rangelands are the most common and the most important factor of rangeland degradation which causes a reduction in species diversity.

In order to investigate the effect of different grazing intensities on species diversity and uniformity in the rangelands of the southeastern slopes of Sabalan, three habitats with different grazing managements including light, medium and severe grazing were selected and one square meter plots along three 200-meter transects were sampled. In each plot, the list of available species, canopy percentage and number of individuals of each plot were recorded. Simpson, Shannon and Brillon diversity indices and Camargo, Simpson and Smith-Wilson uniformity indices were calculated.

The results showed that the area with medium to light grazing intensity has the highest diversity and uniformity compared to the area with heavy grazing intensity which indicates favorable conditions for the establishment of several species. 

Discussion and Conclusions

Due to the significant effect of grazing intensity on diversity and richness indices, it is necessary for rangeland managers to control grazing intensity through management methods to maintain the diversity of rangeland ecosystems. Therefore, it is enough to target the management based on moderate grazing and bring the areas with intense grazing to the conditions of moderate grazing so that the good and tasty species gradually replace the woody and poor species. Desirable species and plant species and woody species are poor.

Forest decline is an important and complicated phenomenon that happened in most world oak forests. This research aims at the determination of mortality rate, the volume of deadwood, and also the designation of the ecological factor affecting these mentioned parameters in Tange Alamdar, Behbahan. To do so, a 50 hectares oak forest was selected and 30 systematic randomized sample plots (25 Are) were established in this site. Within each sample plot, mortality rate, deadwood volume in different classes (coarse and fine dead wood), slope, elevation, landform, and terrain shape indexes, and aspect were recorded. Pearson’s correlation coefficient and one-way ANOVA were used for data analysis. The result indicated that standing dead tree, fallen dead tree, and fine woody debris volume were 7.01, 15.21, and 0.039 m3 ha-1, respectively. Persian oak mortality rate in the studied site was 57 percent and the highest rate belonged to the 10-15 cm d.b.h class. The high rate of mortality had no correlation with elevation and aspect. Also, deadwood volume and number in the different studied groups had no significant correlation with physiographical features. A high level of mortality rate in all of the diameter classes might imply that mortality is not the result of aging but some kind of disturbances. One of the possible reasons for low fine woody debris volume could be related to human disturbances. Overall, reforestation should be considered in the studied site to decrease the mortality rate.

This study aimed to evaluate the structural characteristics of Quercus macranthera forests in the Arasbaran region, Hatam Mashe Si, Meshgin-Shahr. To achieve this, all trees and shrubs were full calipered in three one-hectare plots. Additionally, the structural characteristics were measured using the nearest neighbor’s method. To measure intensity of trees, several indices like nearest neighbor distance index (density of trees), uniform angle index and Clark and Evans index (variety of location), Mingling index and Shannon-Wiener index (tree diversity in diameter classes), diameter and height differentiation indices (dimensional differences of trees), and complex structural diversity index (tree diversity) were used. The results showed that Q. macranthera represented a relatively homogeneous structure in its main site, and the mean of distance to the neighbors was 2.59 m. The results of uniform angle and Clark and Evans indices showed that the spatial pattern of trees was regular. Mingling and Shannon-Wiener indices showed a low tendency of Q. macranthera to mix with other tree species so that the majority of trees were Q. macranthera. The height and diameter differentiation indices illustrated that the dimensions of the trees had a slight difference. According to complex structural diversity index, tree diversity was at the medium level. It can be concluded that the Q. macranthera communities have a homogeneous structure in a study region with a low mixture and single canopy layer. The information can provide the opportunity to monitor future changes in Q. macranthera communities in this region. To promote ecosystem stability, it is suggested to create heterogeneity of stand structure and support other tree species in this area.

Knowledge of the decay trend of dead trees and site factors affecting their functions, plays an important role in the development of conservation management plans in forestry projects. This research was conducted in Asalem beech forests in northern Iran to assess the impact of physiographic features of the site on the process of dead trees decay. A total of 90 sample cuts of dead beech stumps were randomly selected and studied. For each sample, species, diameter and decay classes were recorded. The effect of aspect Slope Index (ASI), Terrain Shape Index (TSI) and Landform Index (LI) on the physical properties of dead wood (density, weight, moisture content) and biochemical components of wood (lignin, cellulose and hemicellulose) on the process of decay were investigated. The mean decay rate of dead beech stumps calculated 0.061 and the mean of beech was 0.32 that varied between 0.05 and 0.62 grams per cubic meters. The results revealed decay process requires about 46 years and the four classes decay showed significant difference in terms of wood density, lignin and cellulose. Meanwhile, the LI was the most important physiographic factors influencing the decay rate of dead trees. The lignin content of the deadwoods was significantly influenced by the form of land. Accordingly, it can be concluded that maintenance certain volume of dead tree in the forest stand structure need to taking account into the dynamics of dead trees, as well as the effects of geomorphological characteristics of site, especially land form conditions

Habitat trees provide diverse microhabitat for various organisms in forest ecosystems. Old-growth phase is one of the determined developmental phases of beech stand dynamics in the north of Iran. This research was carried out in Shafaroud forest in the west of Guilan province to assess the habitat and dead trees in this developmental phase, qualitatively and quantitatively. For this purpose, three one-hectare areas were selected and in each area, quantitative characteristics of habitat and dead trees including abundance, tree diameter, and height were recorded. Results revealed that from the different types of habitat trees, crack trees were the most frequent in the study area (31.7%) while other frequent types were cavities, burr and fork-spilled tress (29.3, 24.4 and 14.7%, respectively). The most frequent tree-related microhabitats were observed on the beech trees. The mean of dead volume in this phase was 37.1 m3 and Shanon and Simpson diversity indices were calculated as 1.9 and 1.7, respectively. Meanwhile, the Margalef and Pielou evenness indices were 0.8 and 0.9, respectively. The findings demonstrate that very thick beech trees (with the diameter of 70 cm and more) show the highest number of microhabitats as well as the most diversity. The presence of tree-related habitat trees in different forms should be considered in the planning and implementation of silviculture.

The most current way for measuring the soil fragmentation is determination of mean weight diameter (MWD). In this study, the adaptive neuro-fuzzy inference system (ANFIS) was used to predict of range soil fragmentation affected by different grazing intensities, distance from village and sampling depth. Present study conducted at 2015 in 3 adjacent rural areas (Alvars, Aldashin and Asbe marz) in Darvishchai watershed in Ardabil County. The studied parameters on the soil fragmentation including different grazing intensities in 3 levels (low, medium and high intensity), distance from village in 3 levels (200, 400 and 600 meters) and the soil sampling depths in 2 levels (0-15cm and 15-30cm). Obtained data were transferred to MATLAB software for the development of ANFIS models. For evaluating the models operation, mean squares error (MSE) and correlation (R2) were used. The result of best ANFIS model in prediction of soil fragmentation was compared with results of regression model. The results show that different grazing intensities, distance from village, sampling depth and their combinations had significant effect on the soil fragmentation. Increase of grazing intensity resulted in increment of soil fragmentation. With increment the distance from village from 200 to 400 meters, soil fragmentation decreased but with increment of distance, increased. Soil fragmentation in all conditions was higher at depth of 0-15 cm than depth of 15-30 cm. ANFIS model had more precision in prediction of soil fragmentation (R2=0.96) relative to regression model (R2=0.76).

One of the most important conservation actions that can be taken in disturbed forests is the development of enclosed areas that can substantially impact the structure and composition of vegetation. The main goal of forest management plans is to maintain the natural structure of stands. Yew is one of the most important and threatened tree species in the Arasbaran region in northwestern Iran.

In this research, we assessed the structural characteristics and composition of yew forest communities using the nearest neighbor and full callipering methods at three sites with different management histories. Within a one-hectare sampling area, tree species identity, diameter, height, and crown diameter were measured. In each of these sampling areas, 56 sample points were surveyed in a 25 m × 25 m grid for trees species identity, diameter, height, and distance from reference to neighbor trees. To quantify the structural characteristics in areas of different conservation status, some indices calculated including mingling, distance to neighbor, diameter and height differentiation, uniform angle, and Clark Evans.

The average height of yew trees at the long-term sites SKA and SVA was 5.1 and 4.8 m respectively. These trees were located in the lower layer. In the short-term site (SKU), however, yew trees (4.04 m) had approximately the same height as other trees (4.3 m). Results revealed that four species – hornbeam (68%), maple (8%), yew (7%), and oak (5.2%) composed 88% of tree species. The majority of trees had a low distance (2–3 m) between neighbors. Due to the high density of trees in the sites with a long-term conservation period (SKA and SVA), a low percentage of trees had mean distance more than 5 meters. Mean of distance to neighbor (Di) index for long-term and short-term sites were 3.8 and 5.14, respectively. The mean TDi for long-term and short-term conservation areas was 0.59 and 0.06, respectively. The uniform angle index showed that there was no class value 1 at all three sites. In the long-term enclosed area, Clark Evans index was 1.18. In short term-enclosed areas, it was less than 1 (0.82). At all sites, yew trees were in the least vital class.

Reducing tree density and basal area of other species will lend strength to yew trees in the studied sites. However, because yew trees need moderate light conditions, excessive decreases in the tree density can be detrimental. In order to optimize the management of forest resources, it is essential to get the correct information about the structure of forest stands. It is important to obtain enough information about the forest stand structure and changes in various indicators of stand to offer new approaches to forest management. The results of this research can show the conservation effects on yew stands in long-term and short-term conservation periods. It helps provide effective and useful conservation solutions.