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Extended Abstract Background: The complexity of the vegetation structure is an important feature of natural ecosystems, often associated with higher ecological performance. Studies have shown that plant communities that are structurally more diverse are also more complex. However, the shape and overall nature of this relationship, as well as the involved mechanisms, are not well known. On the other hand, the assets and services of forest ecosystems have significantly declined due to destruction and deforestation in some parts of Iran, particularly in mountainous landscapes. This study aims to evaluate the structural changes in forest stands affected by varying degrees of degradation in a mountainous ecosystem. The research focuses on analyzing structural indicators, such as abundance, species composition, density, diameter at breast height (DBH), tree height, and the regeneration status of woody species. The primary goal is to achieve a better understanding of the human disturbance process and its effects on forest structure. Additionally, the study emphasizes providing recommendations and strategies for the sustainable management and restoration of degraded forest stands based on the findings. Methods: This study was conducted in three forest stands within the Abr Forest, located in Shahroud, Semnan Province, each characterized by different levels of disturbance as well as distinct species composition and structural features. In each stand, three sample plots (100 × 100 m) were established along transects following a southern-to-northern direction, corresponding to the general slope and increasing elevation gradient. The transects were aligned parallel to each other. All woody species with a diameter at breast height (DBH) greater than 7.5 cm were measured and identified within each plot. The collected DBH and basal area data were used to calculate several structural parameters, including tree density (N.ha-1), the proportion of large-diameter trees, the Gini coefficient, the structural complexity index, and Doliucourt's diameter differentiation, to compare the stand structure among the different disturbance intensities. The forest structure triangle method was employed to further assess the forest structure based on disturbance intensity. For this purpose, trees were grouped into three DBH classes: small (< 30 cm) medium (30–50 cm), and large (> 50 cm) diameter classes .Regeneration of woody species was recorded within subplots measuring 2 × 2 meters (4 m²) established inside each main plot. Regenerating individuals were categorized into three height classes; less than 0.3 m, 0.3 and 1.3 m, and greater than 1.3 m. Species diversity, richness, and evenness across stands were evaluated using the Shannon–Wiener diversity index. Species diversity, composition, distribution of number and basal area in diameter classes, and regeneration characteristics were compared using the one-way ANOVA test and Tukey's multiple comparisons at the 5% level according to the type of stand disturbance. Results: In total, 2638 individuals belonging to 11 woody species were observed in the study area. The highest and lowest tree densities were recorded in moderately disturbed (346 stems per hectare) and severely disturbed (189 stems per hectare) stands, respectively. Furthermore, the severely disturbed stands exhibited the greatest mean DBH (DBH = 37.46 cm) and mean tree height (11.86 m) among the three stands. The analysis of biodiversity indices showed the lowest species diversity (Shannon index H' = 2.31) and species evenness (0.63) in severely disturbed stands, while the highest values for both diversity (H' = 2.97) and evenness (0.87) were observed in the intact (undisturbed) stand. The distribution of species abundance varied among the investigated stands. The structure of the stands exhibited a wide presence of young and small-diameter individuals (DBH < 30 cm) and alongside a decline in the number of large and old trees (DBH > 55 cm) in all three stands. The moderate degradation stand had the most diversity and abundant regeneration of woody species. The distribution pattern of the number in the diameter classes of the studied stands shows a decreasing or semi-hyperbolic trend, as well as Uneven-aged natural stands, so that their population distribution curve follows an inverted J shape. Carpinus orientalis and Quercus macranthera were the most prevalent in the three stands. In intact and severe degradation stands, these two species constituted 60.5% (667 and 440 individuals) and 22.7% (250 and 165 individuals) of the total investigated individuals, respectively. Moreover, the regeneration frequency of the studied stands was obtained with 335 ± 89 (mean ± standard deviation) seedlings and 132 ± 35 (mean ± standard deviation) saplings (in 4 m2). Conclusion: Human disturbances can significantly impact forest regeneration mechanisms. Certain species demonstrate persistence capacity through vegetative sprouting and asexual reproduction, while others lack this adaptive trait. In the study area, three species exhibited particularly high sprouting potential; Carpinus orientalis, Quercus macranthera, and Carpinus betulus. These species showed remarkable resilience to habitat degradation through vigorous vegetative regeneration, enabling effective site rehabilitation in disturbed conditions. The intensity of exploitation and harvesting was higher in the environment with moderate disturbance and degradation, while it was lower in the severely degraded stand. However, the results indicate that the harvesting and exploitation of trees by local communities and even recreational users do not seem to have adverse effects on the abundance, structure, and regeneration of the studied stands. Instead, other factors, such as illegal logging and trafficking, road construction, gas and electricity transmission routes, land-use changes, and possibly climate change, may play a significant role in the degradation of these valuable stands. Based on the research results, it is recommended to improve the natural regeneration status of native tree species through various afforestation methods. There is an urgent need for protection to ensure sustainable exploitation and management of the forest.

Extended Abstract Background: In dry ecosystems, especially in arid and semi-arid regions, which are fragile and vulnerable ecosystems, forest destruction and land use change are considered one of the most important factors affecting the variability of soil characteristics. In this regard, soil respiration, as the main carbon control process in underground processes, is correlated with soil microbial activity, availability of different substrates, soil nutrient content, root dynamics, soil temperature, and moisture, and is considered a good indicator to estimate the productivity of ecosystems. The long-term consequences of land degradation, soil properties, and microbial respiration, which significantly affect global carbon dioxide emissions, are not fully understood. Thus, this study aimed to investigate the effects of forest destruction and land use change on the physical, chemical, and respiration properties of soils in semi-arid mountain ecosystems. Methods: The current investigation was conducted in the mountainous area of Mikhsaz, Kajur village, which is a part of the Nowshahr City region situated in Mazandaran Province, Northern Iran. The altitude ranges from 1600 to 1700 meters above sea level, with a slope gradient of 10-20%. The area experiences an annual precipitation of 365 mm and a mean annual temperature of 11˚C. Soils are clay loam and are classified under the Alfisoils order according to the Soil Taxonomy (United States Department of Agriculture, 2014). The examined region has the potential for forests (including Carpinus orientalis Mill. and Quercus macranthera F&M.) and rangelands (including Artemisia aucheri Boiss. and Astragalus podolobus Boiss. & Hohen). The study area was predominantly covered with forests, but it has been transformed into three distinct uses, forest, forest-woodland, and rangeland due to human activities during the last 30 years. In each of the studied uses (forest, woodland, and rangeland), four sample plots with an area of four hectares (200 × 200 meters) were considered at a distance of 4-6 km from each other. The selected areas were similar in terms of bedrock (dolomite limestone), physiography (average height of 1650 meters above sea level, the slope of the area between 10 and 15%, and the dominant geographical direction northward), climatic conditions (cold mountains), and management conditions (without human intervention, fertilization, and livestock grazing). The soil was sampled (in an area of 30 × 30 cm from two depths of 0-15 and 15-30 cm) from four corners and the center of each of the sample pieces in summer. In total, five samples were collected in each sample plot, and a total of 20 soil samples were collected from each depth of 0-15 and 15-30 cm in each land cover. To investigate the difference or non-difference of the values of the studied characteristics in the studied habitats, a split-plot design was used for physical and chemical characteristics, and the one-way analysis of variance (ANOVA) was used for biological characteristics with SPSS version 20 software. To determine the relationship between vegetation and soil respiration, graphs were drawn using Excel software. Results: Examining the changes in the physical and chemical characteristics of the soil showed significant differences in the characteristics of micro-aggregate, macro-aggregate, soil stability, weighted mean diameter of soil aggregates, carbon in micro-aggregate, carbon in macro-aggregate, the ratio of carbon in micro to macro-aggregate, nitrogen in micro-aggregate, nitrogen in macro-aggregate, carbon to nitrogen ratio in micro-aggregate, carbon to nitrogen ratio in macro-aggregate, dissolved organic carbon, dissolved organic nitrogen, and dissolved organic matter among three land uses. Moreover, micro-aggregate, macro-aggregate, weighted mean diameter of soil aggregates, carbon in micro-aggregate, carbon in macro-aggregate, nitrogen in micro-aggregate, nitrogen in macro-aggregate, the ratio of nitrogen in micro to macro soil, and dissolved organic matter, carbon and nitrogen showed significant differences in the two soil depths. The results of the changes in soil elements in relation to soil carbon and nitrogen characteristics in three uses of forest, woodland, and rangelands showed that nitrogen in micro-aggregate (0.13, 0.09, 0.05 %), nitrogen in macro-aggregate (0.32, 0.16, 0.08 %), dissolved organic carbon (52.16, 38.05, and 18.41 g kg-1), and dissolved organic nitrogen (27.23, 17.85, and 12.9 g kg-1) showed significant differences (p < 0.05) between the three uses in the first soil depth. The results of soil microbial characteristics showed that the substrate-induced respiration in all the treatments used in forest land use was significantly (p < 0.05) higher than the other two land covers. Conclusion: The findings of this study indicate that the physical, chemical, and biological soil properties are influenced by above-ground vegetation, particularly in the topsoil layer. Therefore, the removal of vegetation can lead to significant deterioration of soil properties in semi-arid regions. Considering that the soil in semi-arid areas is highly susceptible to destruction, the reduction and destruction of vegetation play an important role in intensifying these effects and influencing the provision of ecosystem services in such areas. Furthermore, the relationship between soil respiration and carbon dioxide emissions is intrinsically linked to climate change. The results of this research also emphasize that the conversion of forest areas to other ecosystems has led to changes in the carbon and nitrogen cycle and soil microbial respiration. The results of this research can contribute to the development of sustainable management and restoration programs for degraded areas in similar climates because the high quality of the soil of these forests indicates the high potential of woody vegetation (especially Carpinus orientalis Mill. and Quercus macranthera F&M.) for soil protection and biodiversity. These findings can be the basis for designing educational programs for local communities to preserve natural ecosystems by preventing land use changes and rehabilitating degraded areas. In general, these studies can help improve environmental, economic, and social conditions in different regions. Finally, this study emphasizes the urgent need to use sustainable management practices to prevent further degradation and promote the implementation of restoration techniques in degraded forests.

Extended Abstract Background: Regarding the reduction of forests in the world due to the destruction of forests and fires and the adverse effects of drought and climate change, forest plantation is one of the strategic approaches for protecting and enriching forests. Forest plantations are a very small percentage of the global forest area. According to the estimates, half of the world's industrial wood is supplied by forest plantations. In addition to revitalizing areas, forest plantations moderate climate, prevent soil erosion and air pollution, and create recreational areas. It also prevents soil degradation in dry lands by planting compatible species. In the long term, it will also meet the needs of mankind and reduce the pressure of exploitation of natural forests, and performing some ecosystem services and making changes in the physicochemical properties of the soil and biochemical cycles are the other benefits. Nowadays, its importance has increased due to meeting the growing needs of the pulp and paper industry through afforestation with fast-growing species and limiting the harvesting of wood from natural forests, hence more studies in this field have become inevitable. Unlike many countries, Iran's forest plantation areas do not have production goals and are often in the form of projects with different goals, such as the development of existing forests, desertification and sand stabilization, green spaces on the edge of industries and factories, green spaces, forest parks, and urban forestry, and their collections are mentioned and reported as annual forestry works. Despite the great variety of species used in forestry according to the diverse ecological conditions in Iran, there is no integrated management for the forest plantations of the country. On the other hand, there is no documented information about the process of quantitative and qualitative changes in these forestry operations, and the studies conducted in academic and research societies have often been in the form of case studies and cross-sectional surveys using temporary sampling systems. In line with the strategic policies of the Forestry and Pasture Research Institute of Iran and to create up-to-date and accurate database of the state of forest plantations in Golestan province, forest plantations in the west of Golestan province, including the cities of Gorgan, Aliabad, Kurdkoi, Bandargaz, Aq-Qala, Bandar Turkeman, and Gomishan, were evaluated to investigate the current situation and challenges and present suggestions for improvement. Methods: At first, forest plantations in the west of Golestan Province (including Gorgan, Aliabad, Kurdkoi, Bandargaz, Aq-Qala, Bandar Turkeman, and Gomishan) were identified and analyzed based on the archival information of Iran's forests, pastures, and watershed management organization, the general departments of natural resources and watershed management of the province, and the natural resources departments of Golestan Province. Investigations were performed by recording a forest plantation form, including extracting information such as the history and area of afforestation, identification of the type of planted species, identification of compatible species, evaluation of restoration and reclamation operations, and finally, analysis of the forest plantation program, considering the principle of achieving predetermined goals. An initial database of the quantitative and qualitative characteristics of forestry in the west of Golestan Province was formed with the implementation of this project. Then, by preparing an initial database of the quantitative and qualitative characteristics of forest plantations in the west of Golestan Province, all the quantitative and descriptive information recorded in the ArcMap software was converted into a digital map of carried-out forest plantations separately for each city. Then, the data were summarized and presented in the form of a research manuscript. Results: The ratio of the forest plantation area to the city area in the western cities of Golestan Province was 0.05, and the biggest forest plantation area was in Bandargaz (0.02) compared to the area of the city. The ratio of the forest plantation area to the city area in the surveyed cities was in the order of Bandargaz, Aliabad, Kordkoy, Gorgan, Aq-Qala, Bandar Turkeman, and Gomishan. Compared to the west, most of the forest plantations were done in the east of Golestan Province (83%) due to the existance of more areas suitable for forest plantation. A greater area of forest plantation was carried out in the cities of Gorgan and Aliabad, and the area of forest plantation was zero in the cities of Aq-Qala, Bandar Turkeman, and Gamishan, which indicates the inappropriate distribution of forest plantations in the cities of the province. The main species of forest trees in the west of the province often included Cupressus sempervirens Horizontalis, Cupressus arizonica, Pinus brutia, Quercus castanifolia, Alnus subcordata, etc. Among all forest plantation projects in the west of the province, the Shast Kelate forest plantation project was more successful than all the projects due to the complete protection of this project, as well as the prevention of livestock and wood smuggling. Among the less successful projects was the Ghorogh forest plantation project, where most of the social problems were observed such that many damage to the trees was caused by native people and passengers. On the other hand, a large area of plantation forests has been lost due to its location in the vicinity of agricultural land, encroachment on plantation forest lands, and extensive smuggling. On the other hand, the presence of livestock in the field and the lack of forester have affected the success of this project due to the lack of monitoring and investigating forest plantation projects. Conclusion: According to the success of the projects and the study of their challenges, suitable management solutions recommended for forest plantation projects in the west of the province are to increase the social acceptance of the projects, continuous care and maintenance, and the necessity of pruning in many forestry plantations, the exit of coniferous species and entering broad-leaf species, employing more foresters, considering the ecological potential of the field in revitalization and reforestation, continuous monitoring of these forest plantation projects, proper management of the projects, and harvesting of hand-planted forestry to the useful age.

Extended abstract Background: Destruction of environmental resources is one of the serious challenges in today's societies. However, some of these resources seem to be more destructed in developing countries. Forests are constantly being destroyed as one of the environmental resources, especially in our country, and wood smuggling is considered one of the common methods for deforestation, especially in the forests of the north of Iran. The unauthorized cutting of forest timber and its smuggling phenomenon are among the complex problems of natural resources in Iran. Since forest destruction through wood smuggling has irreparable consequences for other parts of the environment, investigating the areas that lead to wood smuggling is of particular importance. However, considering the importance of wood smuggling and subsequent forest destruction, it can be concluded that this issue has cultural, social, and economic contexts, and knowing these factors and contexts paves the ground for proper planning to preserve and improve forest resources. In this research, therefore, an attempt was made to provide an analysis of the status and quantity of wood trafficking in the east of Mazandaran Province by emphasizing a hybrid approach while identifying the factors affecting wood smuggling in Mazandaran Province (eastern region). Methods: This research was carried out in the east of Mazandaran Province using a qualitative and exploratory method. The present study method is qualitative research based on the interpretive paradigm with an emphasis on thematic analysis. Based on thematic analysis, descriptive coding was first followed by interpretive coding, and finally, comprehensive categories were extracted from the data. The main categories included the organizational-administrative, legal-control, economic, cultural, social, and political context of wood smuggling. The core categories were prioritized after identifying the main themes, core categories, and sub-categories. The categories were scored using a five-point Likert scale, including items of very low importance (1), low importance (2), medium importance (3), high importance (4), and very high importance (5). Research information was obtained through unstructured and face-to-face interviews with the main actors related to the issue of wood trafficking. The sampling method in qualitative field research is qualitative sampling, which is also called purposive sampling or theoretical sampling. In this sampling method, the number of interviewed people, or in other words, the sample size depends on the theoretical saturation of the investigated questions. Research information was collected from four groups of stakeholders related to wood trafficking, including local communities (forest dwellers and ranchers), employees of the Natural Resources Organization, wood buyers and sellers (stockholders and smugglers), and environmental activists through semi-structured interviews. Data were analyzed through the thematic analysis technique. In the present study, various aspects were considered to achieve credibility. Three conventional techniques were used to reach the criterion of trustworthiness (Kval & Brinckman, 2009). After the interviews were implemented, the interview text was examined and evaluated by the participants (validation by members). Besides, the correctness of the codes and created themes was evaluated (analytical comparison) by constantly referring to the text of the interviews. Then, the supervisors and advisors acted as external inspectors in all stages of the research, and the final themes were evaluated by them (audit technique). Results: The sentences from the interviews were re-examined at the beginning of the analysis and the coding stage. At this stage, an attempt was made to extract key categories from the sentences. At first, 49 categories were extracted from the key propositions, and according to the points of commonality, they were placed next to each other and grouped into 22 core categories. These categories were finally classified into six themes related to wood smuggling, including organizational-administrative context, legal-control context, economic context, cultural context, social context, and political-political context. The results related to the prioritization of the key categories of the main themes of wood smuggling in the east of Mazandaran Province showed that the categories "low punishment deterrence", "profitable economic activity", and "economic and income problems" with the averages of 4.2, 4, and 3.9, respectively, in the first to third priorities were among 22 core categories. Moreover, the categories "increasing demand for land in forest areas", "sale of barren land", and "weakness of environmental socialization" were ranked among the 22 core categories with averages of 2.1, 2.2, and 4.3, respectively. Conclusion: In general, the results show that wood smuggling is affected by multiple factors, and all aspects must be considered to control and prevent it. The results of the current research provide detailed information in the field of policy and program adoption to managers and policymakers of the forest sector, which will have a positive result in the formulation and implementation of plans.

Extended Abstract Background: Renewable natural resources, such as forests, have played an important role in human life since the past. The principled and sustainable use of forests requires technical planning. Fundamental and technical planning requires data collection and analysis and obtaining useful quantitative and qualitative information. A data collection method in forest populations is 100% statistics, which is rarely implemented in large forest areas due to technical and economic reasons, and it is used in most cases to compare different sampling methods. Sampling methods with a fixed area are mostly used in the preparation of plans and studies of northern forests. Today, different forest sampling methods have been designed and presented, each of which has its own advantages and merits. The use of these methods requires examining and determining the most suitable ones in terms of ease of implementation, time, and accuracy. On the other hand, the industrial forests in the north of Iran have currently become heterogeneous stands due to exploitation in the past. For this type of forest, using the stratification method combined with sampling methods will be useful and effective. To plan to increase efficiency, speed of operation, and reduce costs, it is necessary to examine and use different sampling methods with fixed and variable areas, including multi-tree sampling. This study is aimed at the effect of forest classification and its combined effect with the fixed area sampling method and the PRODAN six tree variable area sampling method and comparing the accuracy of estimators. Methods: This study was conducted in the Safaroud forests with an area of 176 hectares in Mazandaran Province. The selected areas were measured and recorded using the statistical method of 100% of all the trees in the area (counting limit, a diameter at the breast of more than 7.5 cm). To avoid mistakes and make it easier to perform 100% statistics, the studied area was divided into square pieces with dimensions of 50 × 50 m, and 704 plots were placed in the field. Then, the trees in each of these parts were measured separately. Prodan's six-tree method was carried out in two stages. The first stage was measured in an unclassified area of 176 hectares with a grid size of 100 × 100 m. The second stage of the investigated forest area using the "Neyman" stratification method into three strata in terms of volume inventory, including less than 200 m3, 200-250 m3, and more than 250 m3 per hectare based on Prodan's six-tree method, was performed using new grid dimensions for each stratum. In this study, the effect of segmentation on accuracy and time was investigated using the criterion (E%2 × T). For this purpose, the time required to unload the sample plots for the necessary measurements inside the sample plot and the time required to travel the distance between the adjacent sample plots were also calculated and recorded using a stopwatch. Results: The results of the comparison of the statistical test between the average of the variables calculated with the 100% statistical method (true mean) and six-tree sampling (Prodan) in the first stage without stratification and in the second stage with the implementation of the "Neyman" stratification method showed a significant difference at the level of 0.05%. The results of this study in terms of accuracy and the cost index (E%2×T) show that the error and statistical error of the measurement characteristics in the standing forest with the six-tree sampling method with stratification was lower than the sampling method without grafting. This amount was calculated for the number of trees per hectare as 8811.81 and 5677.52, respectively. The estimated average of the examined characteristics was 35.56% closer to the real average and the error rate was less than the statistical standard with the forest stratification and Prodan's six-tree sampling implementation. The percentage of error reduction in sampling after seeding was calculated at 4.42% for number per hectare, 11.91% for breast cross-sectional area, and 18.48% for volume per hectare. Conclusion: From the results of this study, it can be concluded that it is possible to estimate the characteristics of the number, basal area, and volume per hectare of forests based on the classification and implementation of six-tree sampling methods (Prodan), with a relatively variable area. It is more accurate for planning heterogeneous forests in the north of the country.

Extended Abstract Background: In light of the considerable expansion of the Populus genus over recent decades, numerous researchers from across the globe have directed their attention toward investigating a range of topics pertaining to this genus. This genus is of great importance not only in the wood and paper industry but also in the context of expanding green space in arid and semi-arid areas, where the species of this genus are of particular significance. Euphrates poplar is a distinctive woody species that thrives in arid and semi-arid regions, where it can also serve as a sand stabilizer, enhancing the feasibility of afforestation in such environments. The findings of this study may contribute to greater awareness of Euphrates poplar afforestation using cuttings, particularly given the prevalence of arid and semi-arid regions in Iran, as well as sandy dunes, which are often reforested using cuttings of other species. Consequently, this study may facilitate an expansion in the utilization of Euphrates poplar for afforestation, particularly through cuttings. Methods: The objective of the present study was to evaluate the effects of length, diameter, and cutting position on the initial growth of Euphrates poplar seedlings. The study employed a completely randomized block design with five replications. The Euphrates poplar cuttings were procured from the riparian forests of the Maroon River, situated at a distance of 5 kilometers from Behbahan City. The cuttings were obtained from one to two-year-old woody branches of young to middle-aged trees with a breast height diameter of 15–25 cm, prior to the opening of the buds. The effects of the treatments on cutting length (at three levels: 15, 20, and 25 cm), cutting diameter (three levels of cuttings with diameters less than 0.1, 0.1-0.5, and 1.5-2.5 cm), and cutting position (three levels of the initial branch area (from 10 to 50 cm of the branch), the middle branch area (from 50 to 100 cm of the branch), and the terminal branch area (from 100 to 150 cm of the branch) were investigated on the characteristics of height, collar diameter, length of produced shoots, the number and length of secondary branches, the number and dry weight of leaves, dry weight of roots, dry weight of stems, and dry biomass of seedlings. Results: The results of the analysis of the effects of cutting length, cutting diameter, and cutting position on the height and collar diameter of the Euphrates poplar seedlings showed that only cutting length influenced the height of the seedlings. The 20 cm cutting length treatment exhibited the lowest seedling height. Conversely, the cutting diameter treatment exhibited a notable impact on the collar diameter of the Euphrates poplar seedlings. The lowest collar diameter was observed in seedlings subjected to the cutting treatment with a diameter of less than 0.1 cm. Additionally, the analysis of variance revealed that the number and dry weight of leaves in Euphrates poplar seedlings were significantly influenced by the cutting position, with the highest number of leaves observed in seedlings where the cutting position was located in the initial area of the branch (10 to 50 cm from the branch). The results indicated that the cutting diameter treatment had a significant impact on the dry weight of the leaves of the seedlings. Cuttings with a diameter of 1.5-2.5 cm exhibited the highest dry weight of the leaves. The results of the analysis of variance demonstrated that none of the treatments, involving cutting length, cutting diameter, and cutting position, exerted a significant influence on the length of the produced shoots and the number and total length of secondary branches in the Euphrates poplar seedlings. The analysis of variance revealed that the cutting length, cutting diameter, and cutting position treatments did not significantly affect the length of the produced shoots or the number and total length of secondary branches in the Euphrates poplar seedlings. However, the analysis did indicate that the cutting length treatment significantly affected the dry weight of the seedling roots. The highest root dry weight was observed in seedlings obtained from cuttings with a length of 25 cm. The analysis of variance revealed that the cutting length and cutting diameter treatments significantly impacted the stem dry weight of the Euphrates poplar seedlings. However, the cutting position exhibited no significant influence on the stem dry weight. The highest stem dry weight was observed in the treatment involving cuttings with lengths 25 and 15 cm. Additionally, the highest stem dry weight was measured in the treatment of cuttings with diameters 1.2-5.5 and 0.1-1.5 cm. The analysis of variance revealed that the cutting length, cutting diameter, and cutting position treatments significantly affected the dry biomass of Euphrates poplar seedlings. Conversely, the cutting position treatment did not significantly affect the dry biomass. The highest dry biomass was observed in poplar seedlings obtained from cuttings with lengths of 25 and 15 cm, while the cutting treatment with diameters of 1.5-2.5 cm exhibited the highest dry biomass. Conclusion: In this study, the optimal conditions for longitudinal and diametric growth were identified for cuttings with a length of 25 cm and diameters of 1.5-2.5 cm, which also exhibited the highest seedling stem dry weight. The results demonstrated that the cutting position had no discernible impact on the subsequent phases of longitudinal and diametric growth. However, the cutting position can significantly affect the number of leaves produced in the later stages of growth. Specifically, the closer the position of the cutting is to the connection point of the shoot to the mother trunk, the more leaves it will produce in the later stages. In general, the optimal Euphrates poplar cuttings exhibited diameters of 0.1-2.5 cm and a length of 25 cm. However, the cutting position was not a significant factor in relation to the cutting length and diameter as it did not have a notable impact on the root and stem biomass, leaf dry weight, number, and length of secondary branches. Given the plant's demonstrated resilience to drought and salinity, as well as its ability to thrive in high-temperature conditions, it can be considered a promising option for cultivation in arid and semi-arid regions, including sandy environments.

Extended Abstract Background: The height of trees is among the important components in the field of forest inventory and measurement. Over successive decades, estimating tree height has been a major concern in forest statistics and measurement. The height variable is used in estimating tree volume, classifying stand productivity, and estimating growth rates of trees. It is also one of the important variables in calculating biomass. Another essential characteristic at the individual tree level is canopy diameter, which plays a role in modeling and practical attribute estimation, such as forest canopy cover percentage, leaf area index, and biomass. Until now, the devices and tools introduced in forestry science have only been able to measure a specific component, e.g. tree height, and the need for different tools or techniques arises for measuring canopy diameter. The approach of this research not only leads to the development and use of software capable of measuring the mentioned components but also enables the recording of inventory in designed forms, recording of geographic coordinates of tree bases, storing images taken from the trees, and ultimately creating a data archive from the study area. To achieve these goals, the design and development of a software (application) called HCP, which stands for H: Height, C: Canopy, and P: Pixel, based on the Android operating system, will be considered the essence and necessity of this research. Methods: In this research, the HCP software based on the Android platform was designed and developed according to the devices with the Android operating system and with the Java language. HCP has three parts: database, image processing, and information display. Its user interface was presented in six activity pages, including Set Image, Set Data, Set View, Set Reference, Set Pin, and Set Final, with a SQL database structure. The entire coding, execution, debugging, and testing process was carried out based on API 27 (Application Program Interface) associated with the Android SDK (Software Development Kit), in the Android Studio development environment (IntelliJ). The initial testing process was also carried out with real images stored or produced by the device camera used. A total of 150 trees from Persian Oak species (Quercus brantii Lindl) were selected and their height and canopy diameter were measured to conduct tests and compare the measured height data using Vertex and HCP methods, as well as the measured canopy diameter data using laser meter and HCP. Descriptive indices independent of the distribution type, including the first quartile, median, third quartile, minimum, and maximum, were calculated for the height and canopy diameter components measured by the four methods mentioned above. The Shapiro-Wilk test was used to examine the distribution of the difference in the height and canopy diameter of all trees. Paired t-test was used to evaluate the accuracy of HCP. The HCP error was evaluated by the root mean square error (RMSE) and the Index of Disagreement, which is the result of dividing the absolute value of the difference of the estimated component from the actual value by the actual value. The accuracy of HCP was evaluated using linear correlation and the Index of Agreement. To further investigate the dispersion of the error distribution and to examine the accuracy and precision, the data were grouped into three levels: total trees, 75 tallest trees in terms of height (wider in terms of canopy diameter), and 75 smallest trees in terms of height (canopy diameter). All results were obtained using the R statistical software. Results: The result of the paired t-test at a 95% confidence level indicates no significant difference between the measured heights using the Vertex and HCP methods, as well as no significant differences between the canopy diameter measurements using the laser meter and HCP. The RMSE values were calculated as 0.07 and 0.065 meters for the height and canopy diameter, respectively. The values of the linear correlation coefficient and the index of agreement were reported as 0.999 for both the height and canopy diameter measured with the mentioned methods. The disagreement percentages were calculated as 1.068 and 0.963 for the height and canopy diameter, respectively. Conclusion: Modern methods of measuring tree height need to be improved before they can be widely used in forests, and once the shortcomings are addressed, a new chapter will open in measuring forest components, such as the canopy diameter and tree height. The following seven steps outline the general steps for measuring canopy diameter and tree height by using HCP photography. Finally, based on the examination of accuracy, precision, and error assessment test results, HCP can be introduced as an alternative method for measuring the height and canopy diameter of trees. Step 1: Design and develop HCP (other items include defining Java class file functions to determine tree number, recording time and date of photography, calculating the time difference between images, spatial positioning, copying the original image file to internal memory, resizing images for re-matching, and providing output in csv and zip format). Step 2: Taking pictures of the target tree (neighboring trees) and index. Step 3: Defining and determining the numerical value of the index used in the image. Step 4: Determining the lower points (tree trunk and index), upper points (tree tip and index), and the canopy diameter on the image. Step 5: Correcting all measured components, and Step 6: Starting and performing processing by HCP. Step 7: Automatically measuring all defined components for the target tree (neighboring trees), generating output file, and saving all information related to each image.

Extended abstract Introduction and objective: The creation of sequence mosaics in the forest ecosystem, which begins with the regeneration of life in the canopy, has a significant role in the spatial structure of forest masses and can also provide the possibility of establishment of regeneration by changing the characteristics of the soil. However, this relationship is two-way and awareness of it can be effective in the better understanding of natural processes. Therefore, this research generally aims to investigate and compare soil properties in the canopy and closed canopy of pure and mixed beech stands. Hyrcanian forests host critical habitats of oriental beech. Canopy gaps drive ecological succession by altering soil biogeochemistry. This study investigates variations of soil properties in pure vs. mixed beech stands. This study was conducted to evaluate changes in soil physical and chemical properties in open gaps and gaps under the canopy of pure and mixed beech stands in a series of sixty plots. Objectives: 1) Measuring changes in pH, organic carbon, total nitrogen, phosphorus, and available potassium; 2) analyzing the interaction between forest stands and sampling location; and 3) providing management strategies based on the findings. Materials and methods: The chemical changes in the soil layers of the canopy in the pure and mixed masses of beech were investigated by choosing seven sample plots of 25 hectares (500 × 500 m) inside the parcels 4, 5, 7, 15, 16, 17, and 18 of the series 1 sixty cleats, which were the same in terms of location. After selecting sample pieces, eight canopy and eight closed crowns in pure and mixed beech masses were selected for soil sampling. Soil was sampled from two depths of 0-10 and 10-20 cm using a metal cylinder (diameter 8 cm). The average depth of the organic layer was measured before taking the soil samples, and litter was collected at the site of each sample on a surface measuring 20 × 20 cm. The chemical properties of the soil, including acidity, organic carbon, nitrogen, absorbable phosphorus, and absorbable potassium, were measured after transferring the soil to the laboratory. The parameters were measured according to ISO and Olsen standards. Two-way ANOVA and Tukey’s test (SPSS v26) were used for statistical analyses. Findings: The soil properties, including acidity, total nitrogen, and absorbable potassium, at each of the two depths in different positions of the canopy between the pure and mixed masses showed significant differences, and the depth of the organic layer in the pure mass was significantly different in the openings of the canopy less than those of the closed canopy. Among the investigated variables in the organic layer, none of the measured properties, such as acidity, organic carbon, total nitrogen, and absorbable phosphorus and potassium, were significant in different situations of the canopy. The total nitrogen content in the mixed stand was 32% higher than the pure stand, the total nitrogen in the 0-10 cm depth of the mixed stand (0. 28% ± 0.03) was significantly higher than the pure stand (0.19% ± 0.02), and the potassium in the pure stand was 33% higher. The absorbable potassium in the 10-20 cm depth of the pure stand (180 ppm ± 15) compared to the mixed stand (135 ppm ± 12) showed a 33% increase. There was a 37% decrease in the thickness of the organic layer, and the thickness of the organic layer in the open spaces of the pure stand (3.2 cm ± 0.4) was 37% lower than the under canopy (5.1 cm ± 0.6). A phosphorus increase of 20% was seen in the gaps under the open canopy. The concentration of absorbable phosphorus in the open spaces of the mixed stand was 20% higher than in the under-canopy areas. Conclusion: Over time, canopy lighting creates significant changes in the light and microclimate conditions of the forest floor and changes the soil properties and the cycle of nutrients in the forest soil. The formation of a canopy increases both the complexity of the canopy and the diversity in the availability and cycle of the main nutrient elements in the soil, such as nitrogen, phosphorus, and potassium. These changes are very necessary for seed germination, survival, and growth of forest floor plants. Openings accelerate nutrient cycling by increasing microbial activity and canopy. The reduction of organic layering in these areas facilitates the establishment of canopy species. Increased activity of decomposing microorganisms was observed in open gaps (due to canopy and humidity). Litter accumulation and reduced mineralization were also observed under the closed canopy. The formation of gaps increases both the complexity of the canopy and the diversity in the availability and cycling of major soil nutrients, such as nitrogen, phosphorus, and potassium. These changes are essential for seed germination, survival, and growth of forest floor plants. Gaps accelerate nutrient cycling by increasing microbial activity and light transmission. The reduction in organic layering in these areas facilitates the establishment of light-loving species. Increased activity of decomposing microorganisms was observed in open gaps (due to higher light and humidity). Litter accumulation and reduced mineralization were also observed under the closed canopy. The formation of gaps accelerates the activity of decomposing microorganisms and improves nutrient cycling (especially nitrogen and phosphorus) by increasing light penetration by 30-40% and improving soil moisture. A 37% reduction in the thickness of the organic layer in these areas creates optimal conditions for the germination of light-loving species, such as wild barberry (Berberis vulgaris).The following management strategies are suggested based on the findings:Maintaining the natural dynamics of open stands in mixed stands, 2) selective exploitation of pure stands with priority given to areas with high regeneration density, and 3) five-year monitoring of nutrient concentrations in open stands. These measures will contribute significantly to the preservation of biodiversity and sustainability of Hyrcanian forest ecosystems.

Extended Abstract Background: Earthworms make up a significant portion of the soil's invertebrate biomass and play a vital role in enhancing the physical, chemical, and biological characteristics of the soil. Earthworms enhance ecosystem performance and boost primary production by altering the soil structure and decomposing organic matter. Earthworms are classified into different categories based on their behavior and feeding habits. The most important ones include epigeic, anecic, and endogeic earthworms. Additionally, some earthworms, such as arboreal and corticolous species, inhabit unusual environments. This study aims to investigate the effect of dead wood on the biodiversity and abundance of corticolous earthworms in the forests of the eastern Hyrcanian region. In this regard, earthworm species found beneath the bark of deadwood (four species) were identified and classified in this research. Additionally, an attempt was made to analyze the effect of different deadwood species and their degrees of decay on various indices of earthworm biodiversity and evenness. To evaluate the impact of different locations within the deciduous temperate forests of eastern Hyrcania, the abundance of earthworms was examined and compared under the forest canopy and in forest gaps. Methods: The study area is located in District-1 of Dr. Bahramnia Forestry Project, the eastern part of Hyrcanian forests. The research was conducted in parcels 1, 4, 7, 8, 31, and 32, which respectively include tree cover types of oak-hornbeam, ironwood-hornbeam, hornbeam-ironwood, beech-hornbeam, and beech-hornbeam. In this study, 119 samples of fallen deadwood from four species (beech, hornbeam, oak, and ironwood) were randomly selected from beneath the forest canopy and forest gaps at two elevations, 150 and 950 meters. These samples were classified into four degrees of decay based on their physical characteristics. After separating the bark with a sharp knife, the earthworms underneath were collected and initially stored in 15% ethanol, then transferred to 75% ethanol after one day, and finally to a 4% formalin solution. The earthworms were identified to the genus level using available identification keys. Their mass was measured after drying in an oven for 48 h, with an accuracy of 0.0001 g. Data analysis included the calculation of diversity indices (Shannon and Simpson), evenness (Pielou), and richness (Margalef and Menhinick) indices to investigate the diversity of earthworms. Diversity indices were analyzed using PAST (version 3.04) software. Statistical tests were conducted using SPSS to assess the diversity, abundance, and biomass of earthworms across variables. Results: In a study of four deciduous tree species (hornbeam, beech, oak, and ironwood), four genera of corticolous earthworms were identified: Eisenia, Dendrobaena, Dendrodrillus, and Apporecoeda, with respective abundance percentages of 32%, 20.46%, 45.94%, and 1.6%. Notably, Eisenia showed the highest abundance and biomass among corticolous earthworms, primarily in hornbeam trees. The impact of tree species was significant on corticolous earthworm biodiversity, though differences in earthworm abundance and biomass were not statistically significant. The highest Shannon and Simpson diversity indices were recorded for oak (0.16 and 0.23, respectively), while the lowest values were found in ironwood (0.02 and 0.03). The Margalef richness index was highest in hornbeam (0.14) and lowest in ironwood (0.01). Notably, the greatest abundance and biomass of corticolous earthworms were associated with hornbeam, followed by oak, beech, and ironwood. The Pielou evenness and Menhinick richness indices varied significantly across different stages of deadwood decay. The highest values for Shannon diversity (0.34), Menhinick richness (0.32), and Margalef richness (0.24) were found in hornbeam deadwood at decay stage 2, indicating that biodiversity indices differed significantly across decay stages in this species. ANOVA results also showed that the degree of decay significantly affected the abundance and biomass of corticolous earthworms, with the highest abundance and biomass observed at decay stage 3 and the lowest at stage 1. Conclusion: Among the study variables, including deadwood species type, decay stage, canopy cover (under the forest canopy or in canopy gaps), and altitude, only the degree of deadwood decay significantly influenced changes in the abundance and biomass of subcortical earthworms. This suggests that, unlike forest soils where earthworm distribution is highly variable both vertically and horizontally, subcortical earthworms exhibit a relatively uniform distribution. This uniformity points to the consistent, favorable conditions beneath deadwood bark for earthworm survival. Given the impacts of climate change and human disturbances, maintaining various types of deadwood at different altitudes and canopy positions can play a crucial role in supporting earthworm biodiversity.

Extended Abstract Background: Identifying and studying the plant species of a region, as a fundamental aspect of ecology, yield insights into biodiversity and the reactions of biological communities to prevailing environmental conditions while also providing a thorough understanding of the evolutionary history of plants and the ecological potential of that area. The Darabkla forest in the southeast of Sari City is one of the forests in the lower parts of the Hyrcanian forest zone. Despite the very high importance of studying the flora of plants, there has not been a detailed and focused study related to the flora, biological form, and geographical distribution of plants in this region and this altitude range of the Hyrcanian forest until now. Therefore, this research aimed to identify and introduce the plant species of the region, especially the floor covering this forest, for optimal management and protection of this natural ecosystem. Moreover, providing information on flora, biological form, and geographical distribution of plants can be a basis for conducting other studies, including plant sociology in the region. Methods: The present study was conducted in the Darabkola educational and research forest (area 2612 hectares) located in watershed 74 of the Natural Resources Organization of Mazandaran Province. This area is located in the southeast of Sari City. To identify and introduce the flora of the region, plant species were collected from the entire study area using the Braun-Blanquet method and 400 square meter sample plots with 400-meter grid dimensions, as well as the field survey method, from the beginning of October 2018 to the end of September 2019. The samples were identified with the Flora Iranica, and the biological forms of plants were determined based on the Raunkiaer classification. Results: In total, 141 plant species belonging to 122 genera and 60 plant genera were identified in the floristic study of the educational and research forest of the faculty of Natural Resources, Sari, Darabkola. The Asteraceae family with 13 plant species, the Poaceae family with 12 plant species, and Lamiaceae, and Rosaceae and Fabaceae families with 9, 8, and 7 plant species, respectively, were introduced as the richest plant families in the Darabkla forest. In total, they include 35% (50 plant species) of all species. The genera Carex with 4 species and Hypericum with 3 species were the most diverse plant genera regarding the number of species in the Darabkla forest. The study of the biological forms of the species in the region using the Raunkiaer method showed that cryptophytes (28% with 40 species), phanerophytes (26% with 36 species), trophytes (23% with 32 species), and hemi-cryptophytes (21% with 30 species) were respectively the main biological forms of the vegetation composition of the Darabkella forest. Chamaephytes were the rarest biological form in the region (2% with 3 species). The results of the geographical distribution of plant species in the region showed that most of the plant species belonged to the PL region (48 species) and the ES region (34 species), which is more than 58% (n = 81) of the species assigned to themselves. These were followed by the species of ES/IT/M (16 species, 11%), ES/IT (15 species, 11%), COS (15 species, 10%), and vegetation ES/M (11 species, 8%) . The vegetative regions of IT and IT/M, each with one species, showed the lowest presence in the region. Conclusion: As a habitat rich in biodiversity, the Darabkola educational and research forest provides a valuable opportunity for ecological research. The floristic study in this research showed the identification of 140 plant species belonging to 121 genera and 59 families, which shows the high diversity of this region. In particular, Asteraceae, Poaceae, and Lamiaceae were recognized as the richest plant families, which indicates the high compatibility of these species to the environmental conditions of the region. Morphological analysis shows that cryptophytes and phanerophytes, as the two dominant groups, play an important role in adapting to the ecological conditions of the Darabkla forest. These findings can be a sign of the stability of this ecosystem against environmental changes. The geographical distribution of plants also showed that more than half of the species belong to multi-zones and the European-Siberian vegetation zone. This geographical distribution can help better understand ecological patterns and ecological interactions in these forests. Considering the ecological and scientific value of the Darabkla forest, it is necessary to protect this habitat. The implementation of conservation programs to prevent forest destruction, reduce grazing pressure by livestock, and protect biodiversity should be considered the main priorities. These measures not only help preserve forest ecosystems but also provide an opportunity for future research in the field of ecology, forest management, and climate change. In general, floristic identification and analysis is an efficient tool for understanding the status and biodiversity of forests and can be the basis for deeper research in various fields related to ecology and natural resource management.

Extended Abstract Background: Quercus brantii Lindl., as the dominant species of Zagros forests, has a high ecological and social value. The study of genetic and phenotypic diversity is critical and necessary for understanding the adaptation of forest species to environmental stresses, such as climate change, and it can cause the preservation of genetic resources, restoration, and breeding of forest trees. A provenance trial, in which the seeds of mother trees from populations of different geographical regions are planted in the same experimental environment, is one of the ways to study intraspecific adaptive genetic diversity. Methods: Three provinces from northwest to southwest of Zagros, Baneh (north), Khorramabad (Middle), and Yasuj (South) were selected for research. The mother trees from Khorramabad province were selected from three different altitudes (lower, middle, and upper), and Yasuj provenance from two forest stands (Sapidar and Dehbaraftab). A total of 60 mother trees from all provenances were selected and their seeds were randomly planted in the same conditions in the Yasuj region in November. After the germination of the seeds in the spring of the next year, quantitative and qualitative growth traits, such as height, diameter, volume, the number of leaves, diameter, and height growth during summer, vitality, bending, the number of branches, and survival of Q. brantii seedlings, were measured and calculated in two times, June (before the dry season) and late October (the end of the growing season). Then, quantitative genetic parameters, such as the coefficient of additive genetic variation (CVg), individual narrow-sense heritability (h2), and the coefficient of quantitative genetic differentiation (Qst) of different traits, were calculated and compared in the total provenance and each provenance separately. Results: The variance components between the mother trees in different traits were from 4.7% in the number of branches and bending to 25% for the volume, vitality, and survival of the seedlings. The variance components percentage of traits in different provenances was less than mother trees. It was observed less than 5% in traits, such as bending, diameter, and height growth during the dry season, the number of branches, survival, and the leaf number of seedlings, respectively. However, the height and volume of seedlings, especially in October, had a higher variance in the provenance level (about 20%). The heritability ranged from 0.15 to 0.74 for different trains. The lowest and highest values of CVg were observed in the number of branches and survival percentage, respectively. However, the lowest (less than 0.05) of Qst was observed in qualitative traits, growth during the dry season, vitality, and survival, and the highest value was observed in the height of seedlings in October (0.6). The comparison between different provenances for genetic parameters also showed large differences in heritability, the genetic diversity coefficient, and yield in all the traits measured in the seedlings, except for the height in June. The heritability of vegetative traits increased from June to October in the low-altitude of Khorramabad and Sepidar-Yasuj, but it was the opposite in the rest of the provenances. Seedlings of Baneh showed the highest values of quantitative growth traits, such as height, diameter, and volume, among the studied provenances, while the performance, CVg, and heritability of this provenance for growth during the dry season, vitality, and survival were lowest compared to the other provenances, especially the low-altitude of Khorramabad. Among the studied provenances, the middle and upper altitudes of Khorramabad showed the lowest yield, genetic diversity, and heritability in most of the measured traits. Despite the low performance and survival rate of Dehbaraftab-Yasuj, it had high genetic diversity and heritability, while the Sepidar population of Yasoj showed higher adaptation due to a high survival percentage, but its genetic diversity was low. Conclusion: The results of this research revealed highly significant differences in the phenotypic and genetic variability of traits among provenances. Quantitative growth traits, such as the height, diameter, and volume of Q. brantii seedlings, can be used for the initial selection of seedlings due to their medium and high heritability values (more than 0.4) despite qualitative traits such as bending and the number of branches. Moreover, the low altitude of Khorramabad has higher adaptability to climate change due to the highest survival rate, heritability, and CVg of this provenance in the drier planting site (Yasuj). Therefore, it seems that this provenance has a higher adaptability to climate change, and collecting seeds of suitable mothers in this provenance can increase the adaptability of seedlings and reforestation in the face of global climate changes in the future. On the other hand, based on the results of this research, it can be concluded that the local population does not always have more chances to establish and grow, and factors other than geographical factors, such as climatic factors and rainfall, can be effective. Therefore, it is suggested to study the seeds of different provenances to determine the best provenance for reforestation in each region. Furthermore, since the results showed that the genetic difference between the mother trees is more than the provenance, and due to the high genetic diversity and adaptation of Dehbaraftab-Yasuj seedlings to the climate of Yasuj, the seeds of suitable mother trees in this provenance can be used for the restoration program of Yasuj.

Extended Abstract Background: In recent decades, the escalating impacts of climate change, coupled with increasing anthropogenic pressures particularly in forest ecosystems—have raised significant concerns regarding the degradation of vital natural resources, such as soil and water. Among these pressures, logging operations, especially timber extraction via skid trails, result in substantial physical disturbances to the soil structure and surface hydrological behavior. These activities, create conditions conducive to enhanced surface erosion and runoff generation through soil compaction, reduction of vegetative cover, and increased effective slope. Hydrological and geomorphological processes, such as the transformation of rainfall into runoff and sediment transport, are strongly influenced by soil properties, slope gradient, rainfall intensity, and land-use practices. Consequently, examining both the individual and interactive effects of these factors, particularly in ecologically sensitive forested regions, is essential for formulating sustainable land management strategies. This study aims to quantitatively and qualitatively assess the influence of soil properties and slope gradients on runoff generation, sediment yield, and rill erosion along skid trails in Compartments 106 and 107 of the Loohe Forest Management Plan in northern Iran. The research endeavors to enhance our understanding of the environmental implications of timber extraction and provide a scientific foundation for the sustainable management of soil and water resources. Methods: To meet the study objectives, the skid trails were categorized into five slope classes: less than 5%, 5–10%, 10–15%, 15–20%, and 20–25%. Three treatment types: (1) wheel track (machinery path), (2) trail centerline, and (3) undisturbed control area (natural forest without anthropogenic interference) were identified within each slope class. Soil samples were collected at three depths (0–10 cm, 10–20 cm, and 20–30 cm) from each treatment using steel cylinders. Physical soil parameters, including texture, bulk density, porosity, and gravimetric moisture content, as well as chemical properties (such as organic matter content and electrical conductivity), were analyzed in this research. To simulate hydrological processes, a rainfall simulator was employed to deliver precipitation at an intensity of 65 mm/h for 30 min, reflecting a 10-year return interval for the region. Hydrological and erosional variables, including runoff volume, time to runoff initiation, runoff coefficient, sediment concentration and yield, and rill dimensions (depth and width), were measured and recorded after simulated rainfall application. Statistical analysis of the data was conducted using the Analysis of Variance (ANOVA) and mean comparison tests at a 5% significance level to evaluate both main and interaction effects. Results: The results indicated statistically significant differences (p < 0.05) among treatments (wheel track, trail center, and control) and slope classes for most of the measured variables, including runoff volume, sediment yield and concentration, runoff coefficient, runoff initiation time, and rill erosion intensity. The highest values of runoff and sediment yield were recorded in the wheel track treatment, identified as the most compacted and disturbed area due to repeated machinery traffic, particularly on slopes exceeding 20%. In contrast, the control plots, characterized by natural vegetation and the absence of mechanical disturbance, exhibited the lowest values across all variables. Soil compaction in the wheel tracks, evidenced by increased bulk density and reduced porosity, resulted in a marked decrease in infiltration capacity, thereby promoting increased surface runoff. The interaction between soil properties and slope gradient significantly influenced the hydrological and erosional responses; steeper slopes amplified the negative effects of soil compaction on runoff and sediment production. Moreover, runoff volume demonstrated greater responsiveness to environmental changes compared to sediment yield, reacting more rapidly and directly to alterations in physical conditions. This suggests that runoff may serve as a reliable early indicator for identifying areas at risk of erosion in disturbed forest environments. Conclusion: The findings of this study underscore that timber extraction via skid trails significantly alters soil physical characteristics due to mechanical compaction and, when combined with steep slopes, exacerbates runoff, sediment generation, and rill erosion processes. The wheel track treatment emerged as the most vulnerable area hydrologically and erosively due to its elevated soil compaction. These results highlight the urgent need to reevaluate the planning and implementation of skid trails, advocating for protective measures, such as revegetation, mechanical soil stabilization, slope limitation, and designated routes for machinery movement. Ultimately, this research provides a scientific basis for the development of technical guidelines aimed at promoting sustainable forest management and conserving natural resources in mountainous regions. The outcomes may serve as a valuable resource for forest managers, natural resource engineers, and policymakers.

Extended Abstract Background: Forest fire is very common in all ecosystems of the world that affects both vegetation and soil and is also helpful in maintaining the diversity and stability of ecosystems. The effect of forest fires and prescribed fires on forest soil is very complex. It affects the organic matter, macro and micronutrients, and physical properties of soil, such as texture, color, pH, and bulk density, as well as soil biota. Fire is a natural factor in the forest that temporarily reduces the vegetation on the soil surface. After a fire, the soil can experience long-term, medium-term, and short-term changes, which are different depending on the type of soil characteristics, weather conditions, duration, intensity, and frequency of the fire. The Zagros forest ecosystem is generally in the coppice form, and these forests are not safe from fire, which constantly affects them. Considering that the long-term stability of these forests depends on maintaining the soil quality, it is essential to investigate the effects of fire on soil properties. This study aimed to investigate the effect of fire on Zagros forests in Kermanshah province, Gahvareh city in the Lerini region. Methods: The studied area is a part of Zagros forests in Kermanshah province, Gahvareh city, the Lerini region located at 34° 10' 35″ E and 46° 34' 28″ N, with an average height of 1468 m above sea level. In this research, the points were determined by measuring with a meter on transects, and they were sampled regularly in specific time intervals (October, November, February, April, and June). The distance between the samples in each row was 20 m and the distance between the rows was 50 m, and three rows were determined in each of the burnt and control areas. Some soil characteristics, such as pH, electrical conductivity (EC), organic carbon, absorbable phosphorus, soil respiration, microbial biomass carbon, substrate-induced respiration, and metabolic quotient, were measured in soil samples. The effect of the treatments on all measured variables was investigated by the two-way ANOVA. Means were compared by Duncan’s Multiple Range Test (DMRT). Data were analyzed using the Windows version of SAS (version 9.4, SAS Institute Inc., Cary, NC). Results: The soil pH decreased with the passage of time and a decrease in air temperature under the crown (unburnt and burned) and outside the unburnt crown. An upward trend in the pH of the soil in these three places occurred after the cold season. The soil pH ranged from 7.31 to 7.66 in all treatments from October to June. The results of the two-way ANOVA showed that the fire and sampling location did not affect the soil EC in different months of sampling. The amount of absorbable phosphorus increased with the occurrence of fire. The highest and lowest amounts of absorbable phosphorus occurred under and outside the burnt and the control crowns, respectively. The range of organic carbon changes indicates that soil organic carbon has increased over time in all treatments. The highest and the lowest increases were observed under the burnt (1.51%) and the control (unburned) crowns, respectively. Examining the changes indicates that the basic soil respiration was high at the beginning of the fire but decreased gradually, and then the initial value also increased in the last months of sampling. In this research, the amount of basic respiration in the soil of burned areas is not higher than that of unburned areas despite the occurrence of fire and the negative effect on soil organic carbon. According to the results, the amount of substrate-induced respiration decreases under and outside the crown (burnt and control) with the passage of time and the decrease in temperature. According to the ANOVA results, the effects of fire and the sampling location were significant on the microbial metabolic quotient of the soil, although no significant interaction effects on the microbial metabolic quotient were observed in February and June. The highest and the lowest microbial metabolic quotients were measured under (0.94 mg C/mg MBC.day) and outside (0.26 mg C/mg MBC.day) the unburned crown, respectively. With the passage of time and a decrease in temperature, the amount of this parameter decreased in the treatment under the crown of the unburnt area and increased in the three treatments under and outside the burned crown and outside the unburnt crown. At the end of the period, the highest and the lowest microbial metabolic quotients were measured under (0.72 mg C/ mg MBC. day) and outside (0.59 mg C/ mg MBC. day) the crown of the burned area, respectively. Conclusion: The results showed that the fire was superficial in both places under and outside the crown and did not significantly affect the soil’s chemical and biological characteristics. Therefore, no significant changes occurred in indicators such as soil organic carbon and EC, and the fire only increased phosphorus in the burned areas compared to the control. Due to the occurrence of surface fire, combustion did not significantly increase biological indicators. The results of this research demonstrate that the fire changes the soil’s chemical and biological characteristics when it occurs with a higher intensity and at a higher temperature.

Extended Abstract Background: The plant biodiversity of any ecosystem is directly affected by its vegetative characteristics and diversity of plant species, which always guarantees the ecosystem’s stability against variable environmental and biological factors. Biodiversity indices are measured to compare the biodiversity of different masses and estimate the changes in biodiversity over time at the mass level. The Hyrcanian forests of northern Iran are a legacy left from the third geological period, and today a large part of them has been destroyed in the plains due to destructive human activities. These forests have a special importance for the protection and management in the south of the Caspian Sea. Hyrcanian boxwood (Buxus hyrcana Pojark.), which belongs to the Buxaceae family, is the only species of boxwood in the Hyrcanian forests of Iran. It has unique values from various aspects, including economics, tourism, preservation of biodiversity, etc. This valuable species has been threatened by human and natural factors for a long time and its area has decreased in the country. The present research investigates the floristic-physiognomic status of boxwood habitats in Cheshme Bulbul, Sangdeh, Si-Sangan, and Shafarood regions. Methods: In this research, the important habitats of Hyrkanian boxwood were sampled from the protected area of Cheshme Bulbul, Bandar Gaz, Golestan province, as the easternmost distribution area of this species in Hyrkanian forests to Shafarood forests in Gilan province. In total, 125 sample plots of 400 m2 (20 × 20 m) were planted in the four identified areas (35, 30, 40, and 20 sample plots in Bandar Gaz (Cheshme Bulbul), Frame (Sangdeh), Si Sangan, and Shafarood, respectively). To measure the herbaceous cover of the forest floor in each sample plot, five small plots of four m2 (2 × 2 m) were walked in the center and four corners of each sample plot to harvest their herbaceous cover. Biodiversity indices, including Shannon, Simpson, and Fisher diversity, Margalf and Menhinik richness, and Pilou, Simpson, and Shannon uniformity, were measured for each of the sample plots. The plants were identified very carefully using the Persian Flora of Iran, the Flora of Iranica, the Flora of Türkiye, and the Flora of Europe. The biological form of any plant was determined and recorded based on the Rankier method. The range of geographical distribution was determined according to the mentioned flora. Then, the belonging of each species to the existing phytochorions was determined and the geographical distribution diagram of the regional plants was drawn using floristic data in the division of the vegetative regions of the earth's surface. Species diversity between habitats was compared with the one-way analysis of variance. Means were compared using the Tukey-HSD test in SPSS software. Graphs were drawn using Excel software (2013). Results: In total, 186 plant species belonging to 68 plant genera were identified in the studied regions. The hemi-cryptophytes (65 species, 34.94%), phanerophytes (40 species, 21.5%), geophytes (37 species, 19.90%), trophytes (36 species, 19.35%), and cryptophytes (5 species, 69.2%) dominated the vegetation composition of Hyrkanian boxwood habitats. Kamephytes were the rarest biological form in the region with a percentage (3 species). The results of the geographical distribution of plant species in the region showed that the entire flora was mainly of European Siberian (55 species) and multi-regional (38 species) elements, which accounted for more than 50% of the species (93 species). This was followed by Europe-Siberian/Turanian Iran/Mediterranean vegetation areas (25 species, 13.44%), Europe-Siberian/Turanian Iran (25 species, 13.44%), Turanian Iran (16 species, 60.8%), Europe-Siberian/Mediterranean (13 species, 6.70%), and cosmopolitan (8 species, 4.3%) species. The lowest presence in the region was observed for the vegetation areas of Mediterranean/Turanian Iran (5 species, 2.70%), considering that the northern forests are geographically located in the Auxin-Hyrcania state of the Pontic sub-region, which is a large vegetation area belonging to Europe-Siberia. The presence of species belonging to this geographical spectrum in the flora of these regions is not far from expected. Moreover, the presence of species in other geographical areas is a result of the natural patterns of the accidental presence of plant elements from other vegetation areas of the world. Conclusion: The results of this research show higher indices of diversity, uniformity, and species richness in Shamshad Frame and Shafarood habitats, which have a higher average height above sea level than Cheshme Bulbul and Sisangan habitats. The review of the sources shows that physiographic factors play an important role in the indicators of species richness and diversity. Changes in altitude above sea level often lead to changes in environmental conditions, such as temperature, precipitation, and soil characteristics. This diversity in habitat conditions increases its heterogeneity and allows a wider range of species to coexist. As a result, more habitat heterogeneity leads to higher species diversity, which is also reflected in the biodiversity index.

Extended Abstract Background: It is essential to investigate the depth, strength, and main mechanisms of edge effects and recreational activities to preserve species diversity in forest ecosystems. This study aimed to evaluate edge effects and recreation on woody and herb species composition, richness, and diversity in Hyrcanian broad-leaved forests. Methods: Two treatments (control and recreational regions) were determined in the Noor forest park, Mazandaran Province, to achieve research objectives. Five transects from the edge to the forest interior were established in each region. Measurements of herb and tree layers were collected at -5 (out of the forest stand), 0 (forest edge), 25, 50, 100, 150, 200, and 300 m along each transect. In total, 45 sample points were assigned to each treatment. To collect data on tree and shrub canopy cover, two rectangular sample plots of 200 m2 (20 × 10 m) were laid out perpendicular to the transect on the left and right sides at each point. The count, diameter at breast height (> 5 cm), height, and canopy cover percentage were the variables measured in the identified tree and shrub species. For sampling herbaceous species, 10 one-m2 (1×1 m) subplots, with five subplots on each of the right and left sides spaced one m apart, were determined at each sampling point. The type and abundance of herbaceous species were recorded. Using a light sensor device (model Lycor 250), the amount of light entering the forest floor at a height of > 1 m above the ground surface was recorded at each sampling point. The species richness and diversity of tree and herbaceous strata in the sample plots were evaluated using the total number of species present in each sample plot, the rarefaction method, Shannon-Wiener species evenness, and species diversity indices. The SHE method was used to determine the contribution of species richness and evenness to the measurement of species diversity. After calculating species diversity indices, GLM analysis and the Tukey test were used to compare means between treatments. The magnitude of edge influence (MEI) and DEI for all were calculated for species diversity indices and environmental variables. DEI for each variable was calculated using the randomization test of edge influence (RTEI). Data were analyzed with R software version 4.3.1. Results: The light near the edge was more than the interior in the study areas, and the edge positively affected the amount of light. Based on the results of the Rarefaction method and overlap of confidence intervals of the curves related to the study areas, no species richness differentiation was observed between the control and recreational areas. However, the non-overlap of the tree diagrams reveals the highest and the lowest tree species richness in the recreational and control areas, respectively. DEI values of light were -5, 0, 10, and 50 m in the control forest and -5 and 0 in the recreational area. The number of trees per hectare in distances from 10 to 150 m and the volume and basal area per hectare at a distance of 10 m were higher in the control area than in the recreational area. In general, a positive effect of the edge was observed on the species diversity indices of herb and tree layers. The results for the comparison of species diversity indices between the control and recreational areas showed that species richness and diversity of the herb layer were higher in the distances of 10-300 m of recreational areas than in the control area. In the tree layer, higher species richness was recorded in edges of 10-200 m of the control area than in the recreational area. For the evenness index, DEI values were 10 and 0 m in recreational and control areas, respectively. Moreover, DEI values of herb species richness and diversity were 0 and -5 m in control forests. Conclusion: Based on the results, the forest edge is considered an essential part of the forest landscape structure that significantly affects the structure, functions, and species diversity. Regarding the tourism and recreation industry as one of the largest industries in the world and its increasing importance, it is necessary to understand and improve the knowledge about its effects and the severity of its impact (due to the construction of roads) on different variables for better management and biodiversity conservation.

Extended Abstract Background: The leaf area index (LAI) is one of the structural indices of forests and a key variable in the state of forest ecosystems. This index is one of the major structural indices of forests that plays an important role in the processes of evaporation and transpiration and in monitoring the growth of trees. The role of LAI is very important in the changes in the structural quantitative characteristics of forest stands. There is a general relationship between the LAI and the quantitative characteristics of the mass. The leaf area of each tree can be estimated using allometric equations of quantitative characteristics. This research focuses on the effects of changes in the quantitative characteristics, such as tree density (n.ha-1), basal area (m2.ha-1), volume (m3.ha-1), mean height (m), mean diameter at breast height (DBH, cm), crown area (m2.ha-1), and crown volume (m3.ha-1) on the LAI and preparation of their allometric equations in the broadleaf forests of Golestan province. Methods: To collect ground information on LAI, 227 circular sample plots with an area of 1000 m2 with a systematic sampling method and a 100 × 100 m grid were dismounted in five habitats from west to east (Kordkoy, Shasat Kalathe, Zarrin, Gol, Sorkhdari, and Loveh). In the center of each sample plot, the LAI was measured using a leaf harvesting trap with dimensions of 60 × 60 cm. The geographic center of each sample was recorded using a Differential Global Positioning System device. The species type, breast diameter greater than 12.5 cm, the height of trees, large diameter, and small crown diameter are measured, then as tree density (n.ha-1), basal area (m2.ha-1), volume (m3.ha-1), mean height (m), mean DBH (cm), crown area (m2.ha-1), and crown volume (m3.ha-1) located in each sample plot were calculated in each plot. To calculate the LAI, it is first necessary to measure the specific leaf area of all species in the study area. To calculate the LAI, 20 trees were separated from each tree in each habitat and five leaf samples were separated from each tree in four geographical directions. In total, more than 15,000 leaf samples were analyzed and scanned in five habitats. The area of each leaf was measured using ImageJ software. The wet and dry weight and surface area were measured simultaneously using a digital scale with an accuracy of 0.01 and then scanned with a high-resolution scanner. After scanning, the leaves were dried in an oven at 72 °C for 48 hours to obtain their dry weights. Non-linear rational function, Gaussian, hyperbolic, heat capacity, and exponential models were used to investigate the relationship between LAI and the structural characteristics of the stand. Results: The results of the analysis of descriptive statistics showed that the minimum, maximum, average, and standard deviation of the LAI were calculated for 227 samples (1.86, 13.45, 6.33, and 2.33), respectively. The results of the analysis of descriptive statistics also showed that the mean and standard deviation for the characteristics of volume (m3.ha-1), tree density (n.ha-1), basal area (m2.ha-1), crown area (m2.ha-1), crown volume (m3.ha-1), mean height (m), and mean DBH (cm) were respectively (96.96) 298 and 18.205), (24.05 and 12.82), (24.05 and 12.82), (51.148 and 54.155), (2.781 and 05.95), (41.36 and 9.97), and (25.81 and 4.93). The results of the relationships between the LAI and the quantitative characteristics of the volume (m3.ha-1), tree density (n.ha-1), basal area (m2.ha-1), crown area (m2.ha-1), crown volume (m3.ha-1), mean height (m), and mean DBH (cm) of the coefficients of determination showed (36-0.96) R2 = 0.00 with a mean square error of MSE = 0.48-2.06. Among the investigated quantitative traits, the average height, crown volume per hectare, and volume per hectare gained the highest R2 values (0.36-0.96) and the MSE (0.48-2.06) with Gaussian, Richard, and heat capacity allometric models, and the tree density trait (n.ha-1). The lowest R2 (0.36) and MSE (2.06) in the study of LAI were obtained with the Gaussian model. The results also showed large changes in the LAI for the crown volume trait up to 400 (m3.ha-1), followed by a uniform trend. For the average height of up to 40 (m), many changes were found in the LAI. For the volume trait (m3.ha-1), the LAI increased up to 800 (m3.ha-1) and then showed a uniform and even downward trend until 1200 (m3.ha-1). Conclusion: The results of this research demonstrate that the three quantitative traits, viz. crown volume (m3.ha-1), mean height, and volume (m3.ha-1), have the greatest effect on the changes in the LAI. Thus, these three traits can better explain the LAI. The LAI can estimated using the three crown volume (m3.ha-1), mean height, and volume (m3.ha-1) traits. Based on these three traits, the LAI can explained on a large scale, and the estimated results can be used in climate models and the development of appropriate climate change policies.

Extended Abstract Background: Forests are one of the complex ecosystems of natural resources with an important role in the environment and multiple production capacities and functions. The benefit of different human societies from these resources in various forms has various effects and consequences. Without accurate and complete identification of all its stakeholders, logical and acceptable results cannot be achieved in decision-making and policy-making. Therefore, it is essential to fully understand the stakeholders (actors) and their identification criteria in line with basic policies for planning, decision-making, and success in this field. Because decision-making in the management of forest resources always faces challenges and is often associated with complexity, immutability, and uncertainty due to the multi-purpose nature of the benefits and services of these resources, the difficulty of monetary valuation of ecological services, and the great diversity of the stakeholders of their services. Therefore, the stakeholders in the fields of natural resources and forests are considered vital components, and their presence and activity in these fields are undeniable and provide a guarantee of success in cooperative management for the protection of forests. The advancement of the sustainable management goals of natural resources and forests is realized by identifying an active presence of key actors and the most important and effective groups involved, i.e. forest producers and users, along with other identified stakeholders. The primary purpose of identifying those involved is the names of all those who can and should have a role in the planning and management process, and their identification is an important part of the participatory planning process because it is considered a part of the prerequisite for participation. Therefore, identifying and determining the stakeholders make it possible to take advantage of their cooperation in a planned way in the implementation and management of forestry projects and to facilitate the implementation process of the programs. Methods: To identify, weight, and prioritize the stakeholders involved in the Hyrcanian forest ecosystem services using multi-criteria decision-making models, the stakeholders involved in the Hyrcanian forest ecosystem services were first identified and gathered based on the review of various studies. Then, the research questionnaire was designed to answer two important questions in this study: a) who are the people involved in Hyrcanian forest areas? and b) what is their priority? Therefore, the beneficiaries of the economy of Hyrcanian forests were identified by designing a questionnaire scored with a Likert scale, designing items with five priority options, and determining the individuals or groups of stakeholders. In this research, the opinions of 50 experts, academics, and experts of the Natural Resources and Watershed Management Organization at the provincial and regional levels were used to identify the beneficiaries of the ecosystem services of Hyrcanian forests. The questionnaire was validated and confirmed by experts, and its reliability was confirmed with a Cronbach's alpha statistic of α = 0.97. The stakeholders of the forest ecosystem services were weighted with the Step-Wise Weight Assessment Ratio Analysis (SWARA) method, the Simple Additive Weighting (SAW), and Additive Ratio Assessment (ARAS), and the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) was used to prioritize them. Results: By analyzing the findings of the questionnaire using experts' opinions, the Hyrcanian forest ecosystem goods and services stakeholders were identified in 19 groups and five levels, such as international, national, regional, stakeholders outside the forest, and stakeholders inside the forest. Based on the results of the weighting of the stakeholders using the SWARA technique, the forest dwellers and communities downstream of the forest edge are among the most important Hyrcanian forest ecosystem goods and services stakeholders with the highest weight, and other stakeholders were placed in the next priorities based on the received weight. The prioritization of the stakeholders of the goods and services of the Hyrcanian forest ecosystem in the TOPSIS, ARAS, and SAW models showed similar results in terms of the prioritization of the stakeholders of the surveyed services. Conclusion: The results of stakeholder prioritization models were compared using the slope of the service weight curve (R2) in three models. The slope of the relative closeness curve of the weights in the ARAS model was a descending exponential function with an explanatory degree of 0.93, which indicated an obvious difference between the stakeholders of Hyrcanian forest ecosystem services. The slope of the curve of the relative closeness of the weights is higher and closer to one in the ARAS model than in the other two models from different points of view. Based on this result and the consensus of some experts, the prioritization of stakeholders in the ARAS model is closer to reality. Therefore, the ARAS model was proposed as a suitable model for prioritizing the stakeholders of Hyrcanian forest ecosystem services. According to the results of this model, forest dwellers, downstream communities on the edge of the forest, and the off-site users of the forests are considered the major stakeholders of Hyrcanian forest services. Therefore, the role, presence, and influence of these stakeholders cannot be ignored in the management of natural resources and the environment, especially in forestry projects, and it is recommended to optimally use the presence of these communities in cooperative forest management. Furthermore, the human relationship with the natural ecosystem should be at the top of policies and comprehensive management of forest resources. It is necessary to support wood planting projects through subsidy policies and to grant facilities and low-interest loans to forest dwellers and communities downstream of the forest edge. Other necessary measures include efforts to reduce deprivations and increase the socioeconomic development of the villages on the edge of the forest, holding training entrepreneurship courses and classes, introducing handicrafts and non-wood products, identifying target markets, and strengthening the marketing network for the export of non-wood products to increase the share of the forest in the growth and economic development of rural communities on the edge of the forest. Employment programs should also be developed for local communities in the forest protection sectors.

Extended Abstract Background: Oriental beech (Fagus orientalis Lipsky) is one of the well-known industrial species of Hyrcanian forests that spreads from the west to east of these forests. Human activities have caused significant damage to Hyrcanian forests, and this issue highlights the importance of identifying factors affecting the structural characteristics of trees, especially beech, for the optimal management of these forests and the restoration of degraded areas. Considering the effect of environmental factors on the structural characteristics (the basal area and number per hectare) and the distribution of trees, the knowledge of their ecological requirements can be used to prepare programs for the protection and development of forests. Previous research about factors affecting the distribution of this species focused on topographical variables and the effects of climate change. Thus, No research has so far investigated the effect of the frequency of fog occurrence on the structural characteristics of this species. Therefore, the effect of topographical variables (height above sea level, slope, and direction), temperature, relative humidity, and fog on the number per hectare, basal area, and the presence of beech species was investigated in the present study using a generalized linear model (GLM). The results of this research and other studies on the future data from the forests of northern Iran can help predict possible changes in the distribution of species, especially beech species, under the effect of global warming. Methods: To carry out this research, beech species data were obtained from the forest inventory data bank in the north of Iran. Because no meteorological station was available for the whole region of Hyrcanian forests, meteorological data were obtained from the POWER project of the National Aeronautics and Space Administration of the USA. Since fog is defined as water droplets suspended near the earth's surface, which reduces horizontal visibility to less than one kilometer, the occurrence of fog was determined using the horizontal visibility index. After preparing the data, first the number of trees per hectare and then the basal area of trees were calculated in each sample plot. The collected data were separated based on the presence or absence of beech. Data were analyzed using GLM and cross-validation evaluation in R software and the caret package. Results: The results of the correlation between the independent variables showed that the amount of precipitation had a significant and high correlation with relative humidity, hence the precipitation variable was removed from the modeling. The GLM showed acceptable accuracy for predicting the number of trees per hectare (R2 = 0.16), basal area (R2 = 0.16), and the presence of beech species (AUC = 0.75). The fog, height above sea level, and relative air humidity variables had a positive relationship with all three traits (number per hectare, basal area, and the presence of beech species) while temperature was negatively related only to the presence of beech species. The aspect variable had a positive and significant relationship with the number of beech trees per hectare and basal area, respectively, but it was not significantly related to the presence of this species. The height above sea level was the most important variable for predicting the number of trees per hectare, the basal area, and the presence of beech species. Relative humidity was the second most important variable for predicting the number of trees per hectare and basal area while fog was the second most important variable for the presence of beech species. The temperature, slope, and aspect had a significance of less than 20%. Conclusion: The reason for the higher relative importance of the height above sea level can be attributed to low temperature and high rainfall as the optimal conditions for the growth of the beech tree; these conditions are directly related to the height above sea level. Our results also determine the importance of relative humidity and the occurrence of fog in the distribution of beech species. The high importance of the relative humidity variable may result from the fact that beech is generally described as adapting to full-shade to partial-shade conditions. Since the northern aspect (in the Northern Hemisphere) generally receives less direct sunlight and is usually cooler, this species usually establishes in the northern direction in the Hyrcanian forest. On the other hand, since relative humidity increases with decreasing temperature, it can be concluded that beech prefers higher relative humidity. In the forests of mountainous areas and near the coast, the number of fog occurrences is high due to high air humidity and altitude. Finally, this phenomenon leads to rain fog and increases the amount of water reaching the forest floor. Therefore, it can be stated that the occurrence and production of fog play a pivotal role in providing the water needs of beech trees due to the high moisture requirement of this species. The high importance of relative air humidity and the occurrence of fog in the distribution of beech species necessitate additional studies regarding the accurate estimation of the occurrence and amount of fog in Hyrcanian forests. Studies on fog and its effects on vegetation, particularly in temperate regions, can provide valuable insight into the potential benefits of fog for this species. Given the lack of studies, it is suggested to investigate the effects of other environmental factors, including soil properties, on the distribution of beech species.

Extended Abstract Background: Road construction in the forest causes changes in the microclimatic and biological conditions of the roadsides, which lead to positive and negative consequences. Forest fragmentation leads to the creation of smaller habitats and changes in the ecological reactions of the forest, which are different at the distance from the road. These types of changes are called marginal effects. Marginal effects on tree growth indices are different and have been reported from positive to negative in many studies. A review of research records indicates that a few Iranian studies have investigated the marginal effects of forest roads on chlorophyll and carotenoid contents in leaves. Therefore, the current research intends to determine the consequences of forest roads in a part of Zagros forests by examining the marginal effects of forest roads. The contents of chlorophyll a, chlorophyll b, carotenoids, and the specific leaf area index (LAI), as well as the relative humidity of leaves and pollution caused by traffic and the amount of chlorophyll lost in leaves, were evaluated in this research. Methods: To evaluate the positive and negative consequences of road construction, specific LAI, leaf relative humidity, chlorophylls a, b, and carotenoids in leaves, and the amount of leaf pollution caused by dust were studied in the Shoy Forest of Baneh City, Kordestan province. The climate of the region is semi-humid based on the Dumarten climate factor. To carry out this research, a forest road with heavy traffic passing through these forests was selected and three transects were made at a distance of 100 m perpendicular to the road on both sides. At different distances from the road (0, 50, and 100 m), samples of oak (Quercus infectoria Olive.) leaves were collected along the transects. In each transect, the first sample plot of 10 × 10 m was adjacent to the road, and the second and third sample plots were located at distances of 30 and 50 m from the road, respectively. In each plot, leaf samples were collected from all parts of the crown, including infected, damaged, and healthy leaves. The contents of chlorophyll a and b and carotenoids were measured by the Avon method. Oak leaves were taken to the laboratory immediately after collection and their fresh weight was calculated using a digital scale (accuracy of 0.001 g). The surface of the leaves was measured by a leaf surface meter, and the humidity of the leaves was calculated through the weight relationships of the dry and wet weight of the leaves. The total means were compared with the one-way analysis of variance (ANOVA), and the group means were compared using Duncan's test. All statistical tests were performed using SPSS software Ver. 22, and graphs were drawn with Excel software. Results: The marginal effects of road construction on the specific LAI showed that the value of this index decreased with increasing distance from the road, and the highest value was observed at distances of 0 and 50 m from the road. The highest leaf relative humidity was measured at a distance of 50 m from the road, and there was no significant difference at the edge and at a distance of 100 m from the road. No consistent trend was observed in the relative humidity changes, but this variable noticeably decreased on the roadside, which seemed probable. The results of the effect of road construction on the leaf chlorophyll a and b contents showed a decrease in thisvariable with increasing the distance from the road, and the maximum chlorophyll content was obtained at zero distance from the road. Moreover, the highest leaf carotenoids were recorded at distances of 0 and 50 m from the road, and the lowest amount was observed at a distance of 100 m. According to these results, the forest road construction has reduced the light competition between the trees, and those near the road contain more chlorophyll, which can lead to an increase in leaf photosynthesis. The highest contents of chlorophylls a and b were obtained at zero distance (2.01 and 0.97 mg/g of fresh weight, respectively), and carotenoids (0.15 mg/g fresh weight) were maximal at a distance of 50 m from the road, which was not significantly different from carotenoids in the zero distance (0.14 mg/g fresh weight). The results of dust volume caused by the traffic of vehicles showed more pollution of leaves (0.845 g) on the roadside while a leaf contamination level of 0.13 g was recorded at a distance of 100 m from the road. The present findings on the effects of road construction on the amount of chlorophyll lost in leaves showed a significant difference in this variable only at a distance of 0 m from the road, but these differences were not significant at distances of 50 and 100 m from the road. Conclusion: Overall, the marginal effects of forest roads in the investigated area were positive regarding the contents of chlorophylls a and b and carotenoids, as well as the specific LAI, while these effects were negative in terms of pollution. The lost amount of chlorophyll in leaves and the leaf relative humidity index demonstrate the negative consequences of road construction.

Extended Abstract Background: Human activities, climate variability, and environmental stress have strongly affected forest ecosystems worldwide. Forest fires are among the major factors of global ecosystem destruction. Fires in the forest, whether of human or natural origin, have been raised as a serious crisis in recent years. Hence, fire risk assessment plays an important role in forest fire management because knowing where the highest risk is essential to minimize threats to resources, lives, and property. Integration of spatial information from different sources using statistical analysis in the GIS environment is a suitable tool for managing and spreading forest fires, which is one of the main natural hazards in northern Iran. Therefore, it is necessary to prepare a fire risk assessment map for the planning and protection of forests. Methods: The current practical research concerning its nature is a combination of documentary, descriptive, and quantitative model-based methods regarding the research method. In this study, fuzzy and hierarchical (AHP) logic models were combined to investigate the risk of forest fire in Mazandaran province in five classes, very high, high, medium, low, and very low, respectively, using four main criteria and nine sub-criteria, namely topography (height, slope, direction, and rivers), climatic factors (peak temperature and precipitation), human factors (residential areas and the network of communication roads), and biological factors (vegetation). To obtain the net vegetation cover, the Normalized Difference Vegetation Index (NDVI) was applied to the Sentinel-2 satellite image set in a 5-year period (2017-2022) in the GEE web system. The height, slope, and slope direction maps of the study area were prepared from the digital elevation model (DEM) of 12.5 m from the ALOS AVNIR-2 dataset. The distance from rivers, residential areas, and the road network was calculated using the Euclidean distance tool in ArcMAP software. The geographic location of meteorological synoptic stations was obtained from the Meteorological Organization, and its information was used as meteorological input data. In the ArcMap environment, a map of average annual precipitation and maximum temperature was prepared from synoptic stations through interpolation for the period from 2007 to 2021. Based on this modeling method, experts' opinions were used for the relative importance and priority of criteria and sub-criteria in the risk of forest fire in the study area to obtain the fuzzy weight of criteria and sub-criteria. Based on the weighting coefficients applied in the present plan, the final weights of the criteria and sub-criteria affecting forest fire from the highest to the lowest weights belong to the topographical, biological, climatic, and human criteria. Among the sub-criteria, the highest and lowest weights belong to vegetation and slope, respectively. The consistency rate (CR) for the matrices of the affecting factors is equal to 6.25%, which is less than 10%, actually indicating that the weight of the criteria is proportionate and reliable. The highest weights were obtained for the vegetation cover and the slope direction, and the lowest weights belonged to the distance from the river and the slope. Finally, the fire risk assessment map was prepared by combining the fuzzy maps of the sub-criteria in GIS. Results: Overall, medium to very high fire risk potential was found in 72% of the studied area. From a total area of about 2373189 hectares, very low (8.4%), low (18.3%), medium (23.66%), high (25.62), and very high (24%) vulnerability rates were identified in Mazandaran province. Higher fire potential was detected in the East and Southeast parts than in other parts of the study area. The aforementioned fuzzy layers clearly show that the height, slope, and amount of precipitation are low and the density of residential areas and the network of communication roads are high in these parts, with high temperatures. In fact, these factors have increased the risk of fire in these areas. In the present study, the highest fire potential was observed at low altitudes, which could have resulted from the concentration of human activities at low altitudes. Moreover, most fires occurred on low slopes in the studied area. The distance layer from waterways also plays a dual role in the occurrence of fire. The results of the model show an inverse correlation between the distance from roads and fire potential. Based on the results of the fuzzy AHP model, the probability of fire increased with the decrease in precipitation and the increase in annual temperature. A decrease in the amount of precipitation causes a decrease in soil moisture and vegetation, elevating the possibility of fire. On the other hand, the increase in temperature causes the drying of vegetation and reduces humidity, thereby increasing the possibility of fire. Conclusion: It can be concluded that preparing a fire risk assessment map can help managers and planners in identifying areas with high potential and in crisis management in vulnerable areas. The obtained fire risk assessment map can be used as a decision-making support system to predict future fires in the study area.