نشریه بوم شناسی جنگل های ایران
پیاپی 23 (بهار و تابستان 1403)

The Hyrcanus boxwood is the only type of boxwood in the Hyrcanus forests of Iran and one of the few evergreen broadleaf trees in the Hyrcanus forests. Today, boxwood is included in Iran's red list of endangered plants. On the one hand, a major part of the boxwood forests of the Hyrkani region have been destroyed due to the excessive exploitation of boxwood trees during the past decades. On the other hand, the occurrence of the boxwood leaf burn fungal disease and, more importantly, the outbreak of the boxwood moth pest have destroyed large areas of these forests (more than 80-90 percent of them). Due to the importance of the Caspian boxwood and its high value in terms of biodiversity, forest managers are trying to investigate factors affecting this pest in the forest ecosystem. The present study intends to investigate the effect of the boxwood moth pest on the above-below-ground vegetation in the two monitoring periods, namely 2010 and 2022 (before and after the boxwood moth pest outbreak, respectively) in the Buxus hyrcanus Pojark reserve in Sisangan.

The above-ground vegetation was studied with the Braun-Blanquet method at peak vegetation cover by the systematic-selective method in 200 and 400-meter grid dimensions by considering the indicator stand concept in 2010 (and 2022 (before and after the moth pest outbreak, respectively). First, a list of all plant species was recorded in each sample plot by the vegetative form, and then the abundance and predominance of plant species were recorded based on the Brown-Blanke scale. Then, they were accurately identified using the available resources, including Flora Iranica, Persian Flora Collection of Iran, and Color Flora of Iran. The biological form of plants was determined based on the Rankier classification, followed by drawing the biological spectrum. This classification of plants is divided based on the location of regenerating buds where new branches and leaves originate after an unfavorable season. To investigate the geographical distribution or chorology of the plants,  their distribution areas were first determined using the mentioned floral sources, and then the chorotypes of the species were divided based on the classification of geographical areas and toxic floristic areas. The geographical distribution spectrum of plants in the region was also drawn in the form of a histogram.

The results showed that 52 and 69 species in 2010 and 2022 were respectively identified in the Sisangan boxtree (B. hyrcanus Pojark) forest reserve. In 2010, Phanerophytes and Cryptophytes with 44% (23 species) and 19% (10 species) were the most present trees, respectively. In 2022, Phanerophytes and Trophytes with 38% (26 species) and 23% (16 species) were the most important biological spectrums, respectively. The results of examining species diversity, evenness, and species richness indices revealed a significant difference (P < 0.001) between the values of species diversity, evenness, and species richness indices in two monitoring periods (2010 and 2022). The indicators of species diversity, uniformity, and species richness of Rosemary cover were significantly different (P < 0.001/001) between the values of Rosemary species diversity, uniformity, and species richness indicators in two monitoring periods (2010 and 2022). In the examination of the degree of similarity between past and present vegetation of the Shamshad Sisangan Reservoir using Jaccard and Sorenson functions, the degree of similarity of Rosemary vegetation was small in the two monitoring periods. The occurrence of any natural disturbance in the forest communities causes a change in the sequence of vegetation and a decrease in the similarity between the vegetation before and after the disturbance. Therefore, the results of this research showed that species richness and diversity increased with the intensity of leaf-eating by the pest of boxwood moth and the opening of the canopy. Because the characteristics of the disturbance regimes strongly affect the dynamics and sequence of the forest, the use of a conservation management strategy can play an important role in reducing its effects.

This research demonstrates that species richness and diversity increase with the intensity of defoliation by the boxwood pest and opening the canopy. Additionally, because the aboveground in the infected areas is often covered with pioneer and herbaceous species, management strategies should be prioritized to direct the succession path in this reservoir toward the climax stages.

Forest harvesting operations, especially logging, are activities that cause interference and tampering with nature. Tractor-operated systems are the most common type of small-scale equipment used in the north of Iran. Due to the direct contact of wood with the forest soil, land logging has always been associated with a wide range of destructive effects on the forest ecosystem, including changes in the soil's physicochemical properties and damage to the natural regeneration and remaining trees. After logging, deep grooves are visible in the remaining logging roads, which can cause soil erosion, landslides, and soil fall due to the high longitudinal slope of these roads. Changes in the soil's physicochemical properties are among of the most important effects caused by the exploitation and removal of wood from the forest mass. Numerous studies report the long-term recovery of the soil's physicochemical properties. A major management goal in forest exploitation is the need to minimize the effects of vehicle traffic on the forest soil because these negative effects can be significant in the long run. The soil characteristics (appearance, compactness, and texture) and chemical properties in terms of soil elements, organic matter, and pH in two control and forest exploitation areas were studied to provide solutions to reduce these effects.

The Kohmian forestry project is located in the 89th watershed of the northern forests of Iran in the area of Natural Resources of Golestan-Gorgan province. This research was conducted in Parcel 27 of the Kohmian Azadshahr Forestry Project located in Golestan, Iran. To investigate the soil's physicochemical changes due to logging with agricultural tractors, soil was sampled in two control areas and on the crossing paths by metal cylinders at three depths (0-10, 10-20, and 20-30 cm) of the soil in a completely randomized design with three replications. These samples were dried in the laboratory in an oven at 105 °C for 24 h and then weighed using a digital scale (EK4000, Japan) with an accuracy of 0.1 g. After recording the soil dry weight, the physical properties (compaction, apparent specific gravity, moisture, and texture) and chemical properties (organic matter, cation exchange capacity, nitrogen, potassium, phosphorus, calcium, magnesium, iron, zinc, manganese, copper, and acidity) were studied using standard methods.

Logging with an agricultural tractor significantly impacted both the soil's physical and chemical properties. The most notable effect was observed in the soil depths sampled from 0-10 cm and 20-30 cm. The alterations predominantly pertained to physical changes in the soil, with no significant modifications detected in the chemical properties. Notably, soil compaction in the trafficked areas at depths of 0-10, 10-20, and 20-30 cm was respectively 46.2, 3.04, and 1.73 times higher than that of the control area. Furthermore, the increase in soil specific gravity at these depths ranged from 20% to 36% compared to the control area. Chemical properties such as cation exchange capacity and the concentrations of elements (e.g., phosphorus, nitrogen, and iron) exhibited reductions of 37.62%, 63.91%, 10.2%, and 73.05%, respectively, in the top 0-10 cm depth. At a depth of 10-20 cm, only organic matter was significantly impacted by tractor traffic, with a reduction of approximately 64% compared to the control area. Chemical properties at a depth of 20-30 cm remained unaffected by tractor traffic.

The study highlights the detrimental effects of using an agricultural tractor for primary forest plot transportation. The uneven contact surface of its tires, particularly the lower contact surface in the front tire, along with the absence of a winch, leads to soil disturbance along the logging path. This disturbance includes soil compaction, increased specific gravity, and alterations in soil texture, nitrogen, phosphorus, and iron content, reduced organic matter, and decreased soil exchange capacity. To mitigate these adverse effects, it is recommended to employ specialized logging machinery, such as skidders with rakes, instead of agricultural tractors. Other measures include implementing surface protections on logging paths, restricting logging activities to periods when the forest soil is dry and less prone to damage, and proper disposal of excess logs along the logging route.

Afforestation has been growing worldwide in recent decades and is expected to continue in this trend due to the increased use of wood. Therefore, the mass planting of pine trees and other fast-growing species for industrial wood production has intensified since the beginning of the 20th century. In Iran, with a low forest per capita (0.17 ha), per capita plans to create a forest and rehabilitate degraded forests to increase green space have been implemented with non-native species. For this reason, many non-native conifer species have been introduced to the country, which has not been successful in some areas. Therefore, for the success of afforestation with non-native species, it is necessary to select those that are suitable for the habitat conditions, adapt the ecological needs to the environment, and consider the effect of afforestation on the soil, understory plants, and living organisms. Ensuring sustainable management depends on knowing the effects of planted tree species on species diversity, structure, and ecosystem function. Since different tree species have different effects on soil characteristics in ecosystems, they can change soil properties with different mechanisms. In other words, the differences in litter quality, the state of nutrients, the performance of roots in nutrient uptake, the leaf structure, the crown of the tree, the microclimate under the crown, and finally the biological communities in different tree populations change the soil physicochemical properties. In general, the restoration of degraded forest lands through afforestation has a significant effect on the variability of soil characteristics, in which a major difference is observed between native and non-native species as well as broadleaf and coniferous species. Since broad-leaved tree species can positively affect the soil quality of conifer stands, this research aims to compare some soil physicochemical characteristics under the influence of pure and mixed Norway spruce (Picea abies L.) afforestation.

The studied area is in the southeast of section 101 of the Makarood series, watershed 36 (Kazemroud) in Kalardasht city and at an approximate height of 1200 m. It includes the afforested areas of pure Norway spruce (PS) (2 ha), mixed Norway spruce (MS) (2.5 ha) forestry areas, and barren land (BL) (3 ha). Three transects in each area were planned due to the smallness of the areas and the need to adopt a method that best describes the condition of the soil in each area. Then, on the 10, 50, and 90 m points of the transects, soil samples were taken in layers of 0-10 and 10-30 cm (in each area, nine soil samples for each layer). The texture, saturation percentage (SP), electrical conductivity (EC), pH, neutralizing substances or lime (T.N.V), organic carbon (O.C), nitrogen (N), phosphorus (P), potassium (K), and bulk density (BD) was examined in the laboratory.

The bulk density was lower in the 0-10 cm layer in the MS stand (2.28 g/cm3) than in the other two areas. The soil saturation was higher in the upper layer in the PS stand (85.77%) than in the MS stand (59.83%) and BL (51.07%). On the contrary, it was greater in the lower layer of the BL (94.40%) than in the two forest stands. EC values were lower in both upper (0.40 ds/m) and lower (0.38 ds/m) layers in the BL than that in PS and MS stands. The pH was significantly lower in the 0-10 cm layer in the PS (4.84) and MS (4.88) stands than in the BL (5.75). In each of the three areas, the amount of lime was zero in the upper and lower layers. O.C. in the upper layer was significantly higher in the PS (2.57%) and the MS (2.96%) stands than in the BL (1.45%), and the highest value was measured in the MS stand (0.94%) in the lower layer. Nitrogen was higher in the upper layer of PS (0.197%) and MS (0.270%) stands than that in the BL (0.143%). It was higher in the lower layer of the MS stand (0.09%) than the PS (0.02%) and BL (0.03%) stands. The C/N was highest in the upper layer in the PS stand (12.97), but this ratio was not significantly different in the lower layer of the three areas (10.82-11.50). The amount of P was highest in the upper layer in the MS stand (8.4 ppm), but no significant difference in P was detected in the lower layer among the three areas (3.57-5.60 ppm). K content was higher in the upper layer of the PS stand (203.43 ppm), but it was higher in the BL (193.50 ppm) in the lower layer than in the two forest stands. 

In the upper soil layer (0-10 cm), pH, C, and N values did not differ between MS and PS stands, but BD and C/N were lower in the MS stand; on the contrary, soil porosity and P and K contents were higher than those in the PS stand. From this research, it is generally concluded that afforestation with MS has a better effect on the optimization of physical and chemical characteristics in the soil layers than PS, which can provide the basis for more suitable growth of trees and a better balance of the forest.

It is important to research in the field of germplasm protection of native and medicinal tree species in northern Iran forests, especially blood hawthorn with many medicinal properties. Sexual reproduction of hawthorn is possible with apomixis due to the thick shell and two types of physical and physiological dormancy, and its asexual reproduction by rooting cuttings faces many problems. Bloody hawthorn (Crataegus atrosanguinea from the Rosaceae family) is considered one of the valuable species of the forests of the north and west of the country, which is very important due to its fruitfulness, very strong wood, and numerous medicinal properties. The medicinal properties of hawthorn have been proven in the treatment of blood pressure, arteriosclerosis, heart congestion, heart muscle weakness, and coronary insufficiency. Hawthorn contains many secondary metabolites such as flavonoids proanthocyanidin and glycosides. Optimizing the in vitro cultivation conditions of blood hawthorn as one of the natural species of Iran can be a suitable solution for its propagation. The present research was carried out to control pollution, control browning, and induce the callus of blood hawthorn (C. atrosanguinea) in vitro. Controlling the contamination of explants, seeds, and plant tissues is of great importance for the success of plant tissue culture. Since the enrichment of natural plant explants is a priority for tissue culture, this is usually associated with many problems with browning, especially for woody plants that have a thick and woody stem. Determining the type and concentration of the growth regulator of a variable factor is necessary for the growth of plants under in vitro conditions. After applying the growth regulator to the culture medium, the plant will show different reactions, but one of the appropriate ways to choose the correct path of plant regeneration is to determine the wet and dry weights of the callus, which is widely measured as a standard of callus growth. The callus growth curve can be obtained using the wet and dry weights of the callus. The results of past research indicate a wide range of changes in the type and concentration of growth regulators on callus formation and regeneration of different species of the hawthorn genus. A specific type and concentration of growth regulators should be applied according to the type of plant species.

Young and healthy stems of blood hawthorn were collected from Larijan in Amol, Mazandaran province, Iran, with geographical coordinates of 38' 58° N and 10' 52° E, at the beginning of the growing season. The collected stems were immediately transferred to the plant tissue culture laboratory of the Faculty of Natural Resources at Sari University of Agriculture and Natural Resources, Iran. Disinfection of natural hawthorn stems is very necessary due to surface and tissue contamination. For this purpose, explants of 0.5-1 cm size were cut from the stems. The infection control treatments included HgCl2, H2O2, NaClO, and AgNO3, and five treatments were designed to control the browning of explants. Browning control treatments included control, running water, ascorbic acid, polyvinyl chloride, and activated charcoal. In general, the culture medium consisted of substances including mineral salts (micro- and macroelements) as providers of maximum growth, amino acids and vitamins as nitrogen sources, sugar as a source of carbon and energy, growth regulators as growth and morphogenesis stimulants, agar as the solidifier of the cultivation medium, and water, which includes 90% of the cultivation medium. In this research, the culture medium was MS, which was first created by Driver and Koniaki (1984) and prepared according to Dufussard (1976). In this study, the pH of the culture medium was set to 5.8. For callus induction, IBA, NAA, 2,4-D, BAP, TDZ, and Kin treatments at three concentration levels of 0.1, 1, and 6 mg/L and a combination of NAA (6 mg-1) + BAP (1 mg-1), and IBA (6 mg l-1) + BAP (1 mg-1) were used in the MS culture medium. Stem explants were placed horizontally on the culture medium. Among different callus treatments, callus percentage, degree of callus, callus fresh and dry weights, and cross-sectional area of callus were measured to investigate callus induction. The best treatment was obtained by calculating the mentioned characteristics and that treatment was used for planting. It was transplanted approximately every 20 days and a total of 5-6 times. After callus cultivation in the reproduction medium, the explants were placed in a culture chamber and adaptation racks under 16 hours of light and 8 hours of dark treatment at 25 ± 2 °C with a humidity of 70%.

HgCl2 (0.5%, 16 minutes) with an average of 100% health was the most appropriate pollution control treatment. The control treatment with 98% health was observed as the most appropriate browning control treatment. Moreover, the type, concentration, and interaction effect of the type and concentration of the growth regulator significantly affected the callus induction characteristics of blood hawthorn (P < 0.01). The highest fresh and dry weights of callus, percentage and degree of callus formation, and cross-sectional area of callus were observed among auxin and cytokinin treatments, respectively, for 6 mg/L of NAA and 1 mg/L of BAP treatments. The highest levels of the studied callus induction characteristics were observed in the culture medium containing the combination of auxin and cytokinin (6 mg-1 of IBA+1 mg-1 of BAP).

In general, the results showed a 90% chance of controlling the browning of the explants of natural blood hawthorn branches in a normal state and without applying any treatment. It is recommended to use 0.5% mercuric chloride for 16 minutes to disinfect the explants. The combination of growth regulators in the culture medium was evaluated as very suitable for the callus induction of bloody hawthorn. The results of this research can provide laboratory instructions for the regeneration and mass reproduction of blood hawthorn.

The spatial patterns of trees, as the main components of a forest ecosystem, depend on their internal characteristics, interspecific relationships, and external environmental and habitat characteristics. The tree species that make up the forest types are among the major factors influencing soil characteristics through the production of litterfall, and they play an essential role in the quantity and quality of soil organic matter and the release of soil nutrients. Organic matter is one of the important parts of the soil, which includes tissue remains of plants and animals, their undecomposed to partially decomposed components, and dead microorganisms. The presence of organic matter, in addition to indicating the soil fertility and quality, is considered a suitable indicator for soil fertility, resulting from the interaction of physical, chemical, and biological processes. By improving soil granulation conditions, organic matter improves soil porosity and permeability; therefore, it has an important role in the stability of the ecosystem. For this reason, examining its various aspects is one of the main needs and the basis of studies on soil quality, carbon cycles, and climate change. Since there is very little information about the organic matter that can be extracted with hot water as a qualitative indicator of soil organic matter in forests, the need to pay attention to better understand the effect of different vegetation types on the soil leads to a more accurate prediction of the effect of species on ecosystems and their optimal management for managers and foresters. The present study investigates soil organic carbon and nitrogen with hot and cold water extraction methods as an indicator of soil material changes in two pure (Quercus infectoria) and mixed (Quercus libani- Quercus infectoria) types of North Zagros forests (Armardeh Baneh).

Different forest types were determined using the opinions of forestry experts and statistics in the study area. The forestry characteristics were measured with five random 400 m2 sample plots in each type. The topsoil of the studied types was collected using 10 mixed samples from a depth of 0-10 cm (after removing the litterfall layer). After transporting the soil samples to the laboratory with plastic bags, the soil samples were passed through a 2 mm sieve and divided into two parts. A part of the sample was immediately exposed to 4 °C to measure the microbial mass of carbon and nitrogen, and a part of the sample was placed in the open air to measure organic carbon and total nitrogen. After measuring the studied variables, the statistical comparison of the average variables in forest types was evaluated using the independent samples t-test, analysis of variance, and their correlations with Pearson's correlation coefficient. 

The contents of soil organic carbon and total nitrogen in the pure Q. infectoria and Q. libani-Q. infectoria types did not show significant differences. Although the amounts of hot and cold water extractable carbon and nitrogen, the microbial carbon, and nitrogen biomass were higher in Q. libani-Q. infectoria types, this difference was not significant, except for hot-water extractable carbon. There was a significant correlation between hot-water extractable carbon, microbial biomass of carbon, and cold-water extractable carbon. A significant correlation was also observed between hot-water extractable nitrogen and microbial nitrogen and carbon. Finally, there was a significant correlation between soil nitrogen with microbial biomass carbon and cold-water extractable nitrogen, but the correlation coefficient was lower than that of soil organic carbon with microbial biomass carbon and cold-water extractable carbon.

There is an interaction between trees and soil. The growth and production of trees are related to the soil characteristics; on the other hand, the trees with their leaves and unique characteristics affect the understory soil. Based on the study outcomes, it can be concluded that extractable organic matter with hot water can be used as a sensitive indicator of changes in organic matter quality in forest soils.

Sustainable management and fundamental planning of forest resources require efficient and high-quality information about the current and future states of forests. Investigating the current and future states of forest stands, describing the structure of the forest stand, and the response of the stand to tending operations are among the capabilities of statistical distributions in forest management. Frequency distribution modeling is the distribution of people in a population in different classes. Since natural phenomena include continuous and discrete types, their distribution will also be different and diverse. The use of statistical distributions in the forest has a long history, and some researchers have considered its history as long as two centuries. Zagros forests, as one of the most important vegetation areas of Iran, have a special importance from the socioeconomic and ecological points of view. The dominant species of these forests is the Iranian oak (Quercus brantii Lindl). According to geographical and environmental conditions, this species has various habitats in the vegetation zone of the middle Zagros. It is expected that this species has different probability distribution functions in different habitats. Therefore, the probability distribution functions of the characteristic height in habitats with different vegetative structures of Iranian oak in the forests of Khorramabad city were investigated in this research to select the best models in different habitats. This study also seeks to provide useful information on the authority of forest managers and planners to preserve and improve these valuable forests.

To carry out this research, two areas with different structures, including coppice with standard (Sefidkoh area) and standard with coppice (Qala-Gol area) were determined in the forests of Khorram Abad city through numerous excursions in the forest. A forest stand with an area of approximately 3 ha was selected in each of these areas. This forest stand was chosen in such a way to represent the forests of the region. The subsoil was semi-deep and north direction in the Qala-Gol forest stand at an altitude of 1850 m above sea level and with an average slope of 20%. In the SefidKoh forest stand, the subsoil was semi-deep and located in the north direction at an altitude of 1900 m from sea level with an average slope of 30%. In each of these two selected forest stands, the height of all Iranian oak trees, with a height of > 1.5 m, was counted 100%. In total, the heights of 458 and 348 Iranian oak trees were measured in the two SefidKoh and Qala-Gol regions, respectively. A TruPulse 360 laser device was used to measure the height of trees. To investigate the distribution of height classes, the most widely used continuous probability distribution models in biological research were used due to the continuousness of the height variable, including two-parameter Weibull, two-parameter gamma, normal, log-normal, beta, and Johnson. The goodness of fit of the data was also examined using the Anderson-Darling test, which has a higher power than other tests. Easy Fit 5.6 software was used to analyze all data and draw graphs.

The statistical errors were 4.45% and 2.82% in the Sefidkoh and Qala-Gol regions, respectively. The average height of trees was 6.76 m in the Sefidkoh region (between 1.8 and 18 m) compared to that of 7.54 m (between 1.53 and 14.04 m) measured in the Qala-Gol area. The values of skewness and Kurtosis were positive in the two forest areas, with higher values in the Sefidkouh region than in the Qala-Gol area, indicating the concentration of data in lower-height classes in the Sefidkouh region. The results of Anderson-Darling's goodness of fit test in the Sefidkoh area (coppice with standard) showed that the most suitable probability distribution functions (with a 5% error level) for modeling the distribution of trees in height classes were Johnson sb and beta, respectively. In the Qala-Gol region (standard with coppice), the most appropriate distribution functions were identified as beta and normal, respectively.

  The results of this research show that the forest has an uneven-aged structure in the areas where the oak forest has a coppice with standard form, according to the form of distribution (decreasing distribution). In contrast, the forest has moved toward a single-stemmed and even-aged forest in areas where the forest form is standard with coppice. This is mainly caused by the destruction through grazing, the cutting of branches for livestock and fuel consumption, and the indiscriminate use of byproducts that have occurred in this region. In the Sefidkoh region, the effects of destruction and less human intervention were observed at the regional level in field observations. According to the shape of the distributions obtained in the two sites, the vegetative forms of the trees affected the distribution functions of their heights, which can provide useful information for managers, planners, and researchers to maintain and control these valuable forests.

In the Hyrcanian forests, fine woody debris (FWDs) plays a significant role in providing ecological services. However, their importance is often overlooked in the management and executive sectors. Based on the sustainability indices of natural forests—considering changes in carbon stock and the value of wood products—these seemingly insignificant FWDs are predicted to serve as valuable carbon reserves. Both science and economics recognize their significance. To make informed decisions about forestry operations, especially in post-respiration conditions (the rest law of the Hyrcanian forests), it is essential to accurately assess the accumulation and volume changes of these sinks across different parts of the forest. Optimum management techniques, particularly in forestry, can enhance ecological services. Therefore, our upcoming research aims to analyze spatial statistics related to volume stock changes in FWDs within various sections of the Hyrcanian forests, with a focus on implementing optimal management strategies.

The study was conducted in Khairood-kenar forest using a cluster design at different altitude gradients ranging from 100-1800 m above sea level. To create the cluster design, three circular samples with a radius of 7.32 m were placed in the form of a triangle with azimuth angles of 0, 120, and 240 degrees. The distance between each sample was 36.6 m, and an additional sample of the same area was placed in the center of the design. Each cluster was randomly laid with three replications, resulting in a total of 12 samples across the altitude gradient from sea level. On each transact, the diameter of all dry wells, whose central axis was intersected by the transact line, was measured and recorded using calipers. After examining outliers upon the initial analysis, the volumetric observation variograms were fit using various models based on the distance and spatial correlation of variance. Based on the spatial structure, an optimal model, with the highest coefficient of determination (R2) and the lowest residual sum of squares (RSS), was selected for implementing the ordinary Kriging interpolation method. Based on the fitting of the models in different diameter classes, Kriging, and inverse distance weighting (IDW) methods were used for the interpolation and estimation of response variables that were not measured at different distances. Subsequently, the cross-validation method was used to validate the existing estimates of the FWD volume. The accuracy of both the estimation and the performed zoning was evaluated based on the fit between the estimated variable values and the observation values using R2and root mean square error (RMSE) indices.

The total volume of FWDs within the researched forest amounted to 24.3 m3/ha. The volume stocks of the first, second, and third diameter classes of the FWDs were 2.14, 6.01, and 16.23 m3/ha in the study forest. The variogram modeling revealed that the spatial variations in the volume of FWDs across different diameter classes exhibited an average spatial structure. However, the fit was not optimal when considering the R2 and RSS values. Interestingly, the kriging results were most accurate for the FWD first diameter class compared to the other diameter classes. Despite this accuracy, the overall estimated precision remained poor, with an RMSE of 6.32 and an R2 of 0.16. The result of the variography of the volume inventory of FWDs showed that their first diameter class was isotropic and the other diameter classes were anisotropic. Since the kriging method was not effective for estimating the spatial distribution of the FWDs in the second and third diameter classes, the IDW technique was used instead. The results obtained from the IDW technique for evaluating the spatial distribution of FWDs in the second and third diameter classes revealed no significant accuracy in the estimation. Therefore, it can be concluded from the results that the introduction of the volume of FWDs in the forest floor under the altitude gradient is not recommended for the study area.

Based on the results, the volume stock of FWDs for different diameter classes along the altitudinal gradients was independent of autocorrelation and spatial correlation. This means that the FWD volume stock variations in different altitudinal gradients of the study forest are influenced by silviculture, biological, and ecological items with no obvious commonality in this regard. Since the accumulation of the FWD volume in the studied forest is not considered auto-correlated variation, it is expected that the classic tests, such as parametric and non-parametric tests, can be reliably applicable to examine the response variables among the stand types and altitudinal gradients.

One of the basic parameters in forest management is the detailed knowledge of the trees’ growing stock for planning, which is operational by forest inventory. Excessive human interference and dependence on the forests have changed their natural structure. Although the circumstances of wood harvesting are not provided in these forests, their role is essential in soil and water conservation, the livelihood of local people, and environment improvement. Sampling methods must be accurate, inexpensive, and easily implementable in the wild. This study presents a new sampling method, called a branching transect, in the Iranian Zagros forests and similar forests. Features of the new method include proper accuracy, easy implementation in nature, simplicity of statistical calculations, and low cost. The number of trees per hectare (density) in a forest stand represents the existing situation, and its monitoring is very important to know the changes in forest stands. The use of distance sampling methods, especially in open forests, has grown in recent years due to the reduction of inventory costs and optimal accuracy. The research mainly aims to evaluate the efficiency of a proposed distance method (a branched sampling line) with easy implementation and good accuracy in a 100 × 100 m network and the GIS environment.

The studied area is located in the southwestern part of the Manshet and Qalarang protected area in Ilam County. First, 100% inventory was applied in a 90-hectare area of the studied forest, and then 10 and 20-m sampling lines with branches of up to a maximum of 20 m (90 sampling points) were used for this study. In this method, a transect is used that includes some sub-transects. The length of the main transect, sub-transect, the number of trees measured in each sub-transect, and the number of sub-branches in this method are changeable based on the homogeneity, heterogeneity, density, and structure of the forest and are determined according to the forest and expert opinions. In general, less numbers of sub-branches and trees can be considered when the forest is denser or more homogeneous. It is better to consider more sub-branches in dense forests, such as Zagros forests so that a wider area can be covered under inventory and an acceptable number of trees can be examined in transects. Due to the density and heterogeneity of the studied forest area, 20-meter transects with 2, 4, and 6 sub-branches were used in this study. To reach the study goal of the comparison among distance sampling methods, the results of these samplings should be compared to a real amount to have the final judgment on their benefits and weaknesses. Accordingly, the results were compared to 100% inventory in the study area. In 100% inventory, geographical features and the measured quantities for each tree were entered into the GIS environment. This research is the first to use the sampling method of a sample line with 2, 4, and 6 m lateral branches. To evaluate the methods, they compared with 100% inventory based on the accuracy rate and t-test.

The normality of data was tested through the chi-square test, and the unpaired Student`s t-test was used to compare the average numbers and canopy of trees in a hectare, resulting from real amount sampling (100% inventory). Based on the whole amount of trees in the area (12079( and the whole area of the canopy of trees (62.32 m2), the real average amount of trees per hectare and the real average value of the canopy area per hectare were calculated as 141 and 3704, respectively 12). The 6-branched two-tree sample line with 141 trees per hectare and the four-branched one-tree sample line method with a canopy of 3815 m2 per hectare showed the best results compared to the real mean. The analysis showed that most of the used sampling methods  (the branched sampling line with six different patterns 6b2t- 6b1t- 2b1t- 2b2t- 4b2t-4b1t) yielded acceptable results for the evaluation of open forests. However, the branched sampling line method in most networks showed a lower statistical error and was closer to the real value in terms of the mean number of trees per hectare.

Totally, the branched sampling line has an accuracy percentage within 10% to estimate the number of trees per hectare in most networks. In terms of the mean number of trees per hectare, this method was not significantly different from the actual value with a probability of 95% and was more accurate than the other distance methods tested in this research. Considering the low percentage of sampling errors, acceptable accuracy, and easy implementation in nature, the branched sampling line was evaluated as a more suitable method than the other approaches. Due to the novelty of the presented sampling method, there was no case for comparison, in other words, transect branching has not been applied in other areas that can be compared with the results of this study. Finally, the results of this review for the parameters of the number and area of canopy of trees per hectare and its comparison with the actual value and flexibility of this method (changeability of the number of branches, number of trees in each branch, and the length of the main and sub-transects) demonstrate that it is a proper sampling method in dense and even normal forests.

As a forest evolves, it undergoes various processes that lead to the creation of complex structures and diversity. The heterogeneity of the structural conditions and species diversity increase as living and fallen trees accumulate in population structures. These processes are mainly related to the growth and death of trees, which occur in stages starting from youth, progressing through maturity, and culminating in structural complexity. By examining the complexity of a forest, forest experts can manage and change the complexity and diversity of the forest. This study compares the index of structural complexity in managed mixed stands in Hyrcanian forests to determine the effect of management interventions on this index.

For this study, five one-hectare rectangular sample plots were selected in parcels 305, 306, 309, 310, and 311 located in the Grozbon section of Kheyrud forest situated 6 km east of Nowshahr in the Hyrcanian forest belt of Iran. The Gorzbon section has an area of 1001 hectares. The diameters of all trees above the counting limit were measured using complete inventory in one-hectare sample plots. In addition, we calculated the heights of the trees, the abundance of old trees, the abundance and volume of dry trees, the canopy gaps, the Mingling index, and the Gini coefficient. The structure complexity index was determined using a set of variables related to the most important structural features of forest stands. Single selection indices and the multivariate complexity index were calculated in four steps. Finally, the complexity index of the structure was determined between zero and 100 by adding up each variable. The numerical value of the index is close to 100 and zero in the forest stands with the highest and the least complexities in the structure, respectively.

The study examined 1836 trees in five sample plots across five parcels. The highest density of trees was 564 trees per hectare in plot 306. Mamrez was the dominant species in stands 306, 305, and 310  while beech was the dominant species in stands 309 and 311. The maximum average diameter, head volume, and height were 32.5 cm, 458 m3, and 41 m, respectively, for the sample plot 309. The distribution curve of tree abundance across different diameter classes showed a decreasing exponential distribution in the reverse J shape, with differences observed between the studied stands. The largest number of trees in small-diameter classes (15 and 20 cm) were found in cluster 306, with 283 and 137 trees, respectively. The lowest number of trees in the primary classes were 33 and 31 trunks in stand 309. Comparing the volume of trees in diameter classes showed that the volume distribution in all diameter classes was significant in parcel 309, where the volumes in thick and very thick classes were 296 and 83 m3 per hectare, respectively. Parcels 306 and 307 had no quantity of trees in the very thick class. The sample piece 309 had the highest value of complexity index, with a numerical value of 85 while the lowest value of this index (66) was found in the sample piece 305. The ANOVA test with a probability of 5% (P = 0.05) showed significant differences in the abundance and amount of tree volume, the abundance of old trees, the ratio of clear area to forest area, the abundance and volume of dry trees, tree height, and the Mingling index when comparing the studied characteristics to determine the structural complexity index among different populations.

The habitats that have been studied have an average complexity index of 0.75. The highest and the lowest indexes belong to parcels 309 (0.85) and 306 (0.66), respectively. The other habitats have an intermediate level of complexity, which indicates the presence of different evolutionary stages in the forest, ranging from young to old. To illustrate the contribution of different structural features to the complexity and diversity of a forest, imagine a hypothetical forest in both complex and simple states. The complex forest has a wider range of tree sizes and potentially ages, including large trees, while the simple forest has a large number of smaller trees and no large trees, potentially lacking old-age trees. The complex forest includes at least two tree species while the simple forest consists of only one species. The complex forest also has larger erect and decumbent angiosperms on the ground while the simple forest lacks large decumbent angiosperms. Finally, the distribution of trees and canopies, or conversely clearings, is spatially variable in the complex forest, leading to structural heterogeneity in the area. To increase diversity and complexity, measures such as thinning or leaving trees with habitat importance such as thick and old trees, and standing and fallen dry trees in selective cuts can be taken to preserve or restore structural complexity, species diversity, and heterogeneity.

Forests are one of the renewable natural resources and national capitals of every country that provide a wide range of goods and services. Since the lives of local communities and their livelihood are directly and indirectly dependent on forest ecosystems, the management and protection of these natural habitats is an important issue for planners and decision-makers. Today, these valuable resources are threatened by numerous human and natural factors. With the development of technology, industry, and significant population growth, the exploitation and destruction of these natural areas to provide raw materials, space, and food are increasing progressively, leaving irreparable damages in recent years. Accordingly, the present study was carried out to identify the type of use and the degree of local communities’ dependence on the Khamir-Qeshm mangrove forests. The study also seeks to analyze the relationship between the livelihood dependence of local communities and the exploitation extent of these forests. Khamir-Qeshm mangrove forests account for reserves, shelters, feeding and nursing places for many plants and animals. These natural habitats are also the main source of providing ecosystem services for local communities and residents of the edges of these forests. Thus, the ecosystem services of mangrove forests in the studied area are an important tool to show issues such as the livelihood dependence of communities living on the edge of the habitats, the importance of food security, income, health, and sustainable development of human activities. In this regard, the present study complements other studies in terms of the importance of the exploitation of natural mangrove habitats and the use of each of these services in the lives of local communities and residents of the edges of forests. In particular, the areas that are closer to the villages are not of good quality and need more protection.

In the current descriptive-analytical research, data were collected through questions and interviews with local communities. The statistical population of the research consisted of local communities, and a sample size of380 people was calculated in the studied area, which was sampled by the cluster method considering the population of each village. The validity of the research to measure the appropriateness of the questionnaires prepared by structural and formal methods was determined through the opinions of experts and specialists, and its reliability was measured using Cronbach's alpha in SPSS software. The result is statistically confirmed and acceptable, with α = 0.9.

According to the obtained results, the Khamir-Qeshm mangrove forests are mostly used for food consumption, including harvesting wild honey, catching aquatic and edible invertebrates (for home use, restaurants, and selling in the market), hunting birds, and harvesting fodder for feeding livestock (camels). On the other hand, the lowest amount of consumption belongs to harvesting wood from mangrove forests for the construction of pavilions and residential houses. According to the obtained averages, the highest priority in the use of Khamir-Qeshm mangrove forests is assigned to food consumption, followed by tourism, handicrafts, pharmaceuticals, fuel consumption, and construction from the highest to the lowest priority, respectively. In other words, food consumption, especially fishing and aquaculture, is the first priority in this region, and other activities such as tourism, due to the limited time suitable for tourists in the region, making handicrafts, pharmaceutical consumption, fuel consumption, and construction due to the low market demand and necessary facilities have lower efficiency and priority. In addition, the employment of the residents of the area shows the level of livelihood dependence of the local communities on the mangrove forests of Khamir-Qeshm, who exploit these natural habitats for their livelihood and daily needs. In general, the income of most local communities is provided by fishing, although they are also engaged in other activities such as boating, tourism, boat building, and creating ecotourism lodges and beach restaurants. The results of the analysis of the relationship between subsistence dependence and the amount of exploitation of these forests indicate a significant and direct relationship between these two factors. This means that the exploitation level of these forest habitats increases with the increased demand and livelihood needs of local communities. As one of the most important natural resources, mangrove forests have a direct relationship and an undeniable place in providing livelihood, welfare, and comfort to human societies. On the other hand, these forests should always be the focus of planners and decision-makers due to their essential role in strengthening the livelihood and development of human societies.

Considering the protection status and biological sensitivities of the studied area, ‎the continuation of this type of exploitation causes heavy damage to the forests of the area ‎and endangers their survival for future generations. Therefore, management policies and ‎arrangements should be considered to reduce the exploitation of mangrove forests by local ‎communities and to protect and sustain these natural habitats. In addition to this training, ‎informing and empowering local communities in the development of local businesses and ‎increasing their income can help reduce people's livelihood dependence on forests.‎

Extended Abstract

The genus Acer L. (maples) from the Aceraceae are mostly deciduous trees, almost all of which are distributed in the temperate regions of the Northern Hemisphere. This genus contains 148-150 species around the world, and the presence of 8-10 native species of this genus has been mentioned in different floras of Iran. Some species of maples in Hyrcanian forests have great commercial value, and the height of these trees reaches 40-45 m. Maples are the major vegetation elements in most forest ecosystems of Iran. Hyrcanian forests in the north of Iran contain the highest diversity of this genus. Despite the molecular and morphological studies on the taxa of the genus in the world, no comprehensive studies have been conducted on its micro-morphological characteristics. Therefore, the present research describes the taxonomic value of the anatomical features of the leaf epidermis and pollen morphology of the members of this genus in Iran.

Eleven maple taxa available in Iran (nine native and two introduced taxa), mainly from Hyrcanian and Zagros ecosystems, were collected and analyzed in the current study. The investigated taxa were A. hyrcanum, A. velutinum, A. platanoides, A. mazandaranicum, A. campesstre, A. cappadocicum, A. negundo, A. palmatum, A. monspessulanum subsp. cinerascens, A. monspessulanum subsp. turcomanicum, and A. monspessulanum subsp. ibericum. The leaf samples of each individual were prepared from the branches grown in the sun and dried with the herbarium sample method to prevent mold. Dried leaf samples were placed in boiling water for 3 min to prepare dissections. Then, thin slices were prepared from the dorsal and ventral epidermis from the middle of the leaf and in the vicinity of the midrib using a surgical blade. To remove the color of chlorophyll and make the samples transparent, they were placed in a sodium hypochlorite solution for 5 min. After washing with distilled water, they were photographed and studied under a light microscope. For electron microscopy, the dorsal and ventral epidermises and the pollen samples of the taxa were stabled on aluminum stubs. Then, a very thin gold layer was sprinkled on the surface of all pollen and leaf samples using a gold sputter coater and then photographed using a Philips Scanning Electron Microscope. The voltage intensity was 20 kV, and the image magnification was set to 2500-5100 x. Epicuticular waxes, trichomes, epidermal cell wall shape, stomatal type, pollen type, pollen morphological characteristics, and the stomatal density and index were classified and studied from the prepared microphotographs.

The morphology of epicuticular wax was absolutely unique in such taxa as A. velotinum, A. mazandaranicum, A. hyrcanum, A. platanoides, and even some subspecies of A. monspessulanum. The most structured type of epicuticular waxes was observed in A. velotinum, showing circular rosette-like structures formed around some stomata, which could not be seen in the other taxa. The dorsal leaf surface in A. platanoides was also uniquely covered with a completely smooth and uniform layer of wax. Certain wax structures were observed on the surfaces of A. monspessulanum subsp. cinerasens and A. mazandaranicum, making the surface of the epidermal cells appear prominent in the former and indented in the latter taxa. The highest stomatal index and the number of stomata per unit area belonged to two non-native species, namely A. palmatum and A. negundo, and these parameters were lowermost in A. mazandaranicum, A. monspessulanum subsp. turcomanicum, A. velutinum var. velutinum, and A. monspessulanum subsp. cinerascens. Many of the stomata are covered and buried under the thick layers of the epicuticular wax, and there are trichomes and wax crystalloids around other stomata to reduce the rate of evaporation and transpiration. Therefore, it can be acknowledged that the mentioned native taxa have higher drought resistance than others. The epidermal cell wall pattern of the taxa was classified into three different types, the most distinctive of which was seen in A. platanoides, having a completely wavy and puzzle-like wall. Relatively wavy wall was seen only in the epidermis cells of A. negundo. The other taxa showed smooth and straight cell walls. The arrange of subsidiary cells of the stomata was anomocytic in all taxa while the paracytic type was completely distinctive and dominant in A. mazandaranicum. Trichomes in all the owning taxa were simple and branchless, divided into two short- and long-size groups. None of the morphological characteristics of the pollen, such as pollen shape (isopolar prolate to spheroidal), exine ornamentation (striate), the form of pollen colpi, and even the number of pollen pores (Tricolporate), revealed a specific differentiation exclusive to a certain taxon.

The results of the current research reveal that the micro-morphological traits of leaves can help remove the taxonomical obstacles of the genus Acer while the pollen type and morphology do not provide such a capability for the genus. In general, the differentiation of epidermal characteristics among the studied maple taxa shows that the leaf dorsal has useful micromorphological characteristics, especially in terms of epicuticular waxes, which can play an important role in classifying, describing, and determining the boundaries of the taxa to be used as a useful tool in plant biosystematics.

Fire is one of the most significant ecological elements that can alter the functioning of natural ecosystems, as well as one of the most significant natural disasters that endangers the ecosystem of forests. The intensity and frequency of forest fires are increasing daily due to the consequences of global climate change and population growth in sensitive areas. This factor not only damages individuals and property but also poses a serious risk to environmental preservation and the well-balanced ecological conditions of vegetation. Worldwide, thousands of fires in natural areas result in unquantifiable and unfathomable calamities each year. For many years, this problem has been the subject of investigation. The investigation of the fire that occurred in 2021, the conditions of its creation, and its effect on the soil and vegetation characteristics of the Qara Qeshlaq Lagoon are the most important goals of this research.

An area of approximately four hectares of the Qara Gheshlagh Lagoon was burned twice on April 16, 2021, in two different time frames (hours) at 15:30 and 19:30. This area was chosen to investigate the effect of fire on the geological characteristics and vegetation of the wetland. Furthermore, a control area (unburned) was chosen to be close by, of the same size and at the appropriate distance from the burned region. The vegetation was sampled along a transect that ran along these regions. Given that the vegetation in both the burned and control areas is densely covered by Tamarix, 40 rectangular sample plots (a total of 80) with an approximate area of 10 m2 (5 ×2 m) and a distance of 20 m from each other were used to record the height, collar diameter, dbh, small and large diameters of the crown, the number of sprouts, and stem health traits. The percentage of grass cover was determined using a 1-m2 sample plot in the center of the sample plots. Additionally, five randomly selected sample plots were used from the center to measure the soil physicochemical characteristics, including its acidity, electrical conductivity, organic carbon, percentage of lime, percentages of clay, silt, and sand, and absorbable potassium and phosphorus. A soil sample was taken from a depth of 0-10 cm. After determining the normality of the data distribution with the Kolmogorov-Smirnov test, the Mann-Whitney and independent t-tests were used to compare the average quantitative characteristics of the vegetation cover and soil characteristics in the two burned and control areas. In addition, the principal component analysis (PCA) was utilized to explore the most essential fire-related elements in vegetation cover and soil.

At the 99% confidence level, the average collar diameter in the burned region was significantly higher at 4.41 cm than in the control area (3.17 cm). The average dbh (1.64 vs. 1.24 cm) and the number of sprouts (20.05 vs. 14.76) varied significantly in the burned and control areas, with a 95% confidence level. Additionally, a significant difference was observed between the average tree height (1.96 vs. 1.36 m), the percentage of grass cover (70.19 vs. 50.28%), and the stem health (all healthy stems versus all burnt stems) in the control and burned areas at the 99% confidence level. After about a year of the fire, there was a difference in pH characteristics (7.12 vs. 6.73) and sand (27.10 vs. 22.90%) in the two burned and control areas, with a significant difference at the 95% confidence level. A significant difference in the properties of organic carbon (2.86 vs. 1.71%), phosphorus (71.63 vs. 34.28 mg/kg), and potassium (921.40 vs 606.60 mg/kg) was seen in these two areas at the 99% confidence level.  The PCA results revealed an effect of fire on the organic carbon, phosphorus, and available potassium parameters. Among the vegetation cover characteristics, the most effects belonged to the dbh, the collar diameter, tree height, and the large and small diameters of the crown with a factor load greater than 0.8.

According to the current study, the quantitative features of the trees in the wetland were impacted in the burnt area, and changes occurred in vegetation and soil characteristics. As a result, all of the soil properties were significantly higher in the burned region than in the control area. Other than the collar diameter factor, other plant features in the burned region dropped dramatically. Thus, careful management and conservation of such areas following the fire is critical to restore the strength and potential of ecosystems to ensure the continuance of survival and sustainability. Therefore, it is advised to investigate the long-term impacts of fire on vegetation alterations and to accelerate the reconstruction process of the region by protecting such ecosystems and carrying out restoration operations.