حامد اسدی

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.

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).

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.

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.

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.

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.

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%.

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.

Nitrate (NO-3) is an important compound in plant nutrition. However, the leaching of large amounts of it can reduce soil fertility and endanger environmental health and quality of life.

This study was conducted to investigate the effect of rice husk biochar and different types of pure and mixed fertilizers on nitrate leaching from the soil of one-year-old potted saplings of Acer cappadocicum Gled (with an average collar diameter of 17.3 mm and a height of 19.72 cm). This research was conducted in Lajim nursery, north of Iran, using 19 treatments with three replications in a completely randomized design. The treatments included rice husk at 0.5% and 1% by volume, biochar of rice husk at 0.5%, 1%, and 2% by volume, cow manure at 0.75% and 1.25% by volume, and chemical fertilizer at two levels: 1) triple superphosphate 25, ammonium sulfate 18.75, and potassium sulfate 18.75 mg per kilogram of soil and 2) triple superphosphate 50, ammonium sulfate 37.5, and potassium sulfate 37.5 mg per kilogram of soil. The soil treatment of the planting bed (control) and the combination of treatments were also included. To collect drainage water for measuring the amount of nitrate leaching, potted seedlings were irrigated 20% more than the normal irrigation amount, and samples were taken in five stages (from April to September, once before adding ammonium nitrate fertilizer and four times after its addition). In the laboratory, nitrate concentration was measured by the spectrophotometric method. Statistical analysis was performed using R software, and a comparison of means was performed using Duncan's test.

According to the results, in the first stage of sampling, the highest concentration of nitrate in drainage water was observed in the chemical fertilizer level 2. In the second and fourth stages, it was observed in the combination of chemical fertilizer level 1 and 0.75% cow manure by volume, and in the third stage, it was observed in the treatment with 0.75% cow manure by volume. The highest pH value of the drainage water in the first stage of sampling was observed in the combination of chemical fertilizer level 1 and 0.5% biochar. In the second and third sampling stages, the control showed the highest pH value. In the fifth stage, the result was the same as the first stage. Also, the combination of chemical fertilizer level 1 and 0.75 percent cow manure caused an increase of 204, and 0.5% biochar caused a total decrease of 39.4 mg/liter of nitrate leaching.

The results of this research showed that the application of biochar causes a decrease in electrical conductivity and nitrate concentration and an increase in the pH of drainage water. Therefore, considering the beneficial effect of biochar in reducing nitrate leaching and soil salinity, which will definitely bring positive environmental effects, it is recommended to use rice husk biochar to produce seedlings in forest nurseries.

Soil is the largest source of carbon in the biosphere and more than half of its carbon is stored in forest ecosystems. Considering the importance of the soil carbon, the purpose of this research is to investigate how different species of broadleaf and coniferous species affect forest carbon storage in soil, considering their different ability to store and use soil nutrients in the forest Kolet.

In this research, first, three stands of Acer velutinum Boiss, Alnus subcordata C.A.M, and Cupressus sempervirens var horizontalis, as well as one natural forest stand were selected in the study area. Ten samples of 400 square meters (20Î20 meters) were selected in each cluster. Also, soil samples were collected from the four corners and the center of each plot from a depth of 0-15 cm; Then the soils were mixed and a combined sample was separated for the laboratory analyses (40 samples in total), which was used to study the physical and chemical characteristics of the soil (bulk density, soil texture, soil reaction, electrical conductivity, organic carbon, total nitrogen, phosphorus and absorbable potassium). SAS statistical software was used for soil data analysis related variables, and the Vegan R software package was used for principal component analysis (PCA) to identify the most significant factor and differentiate between the studied populations.

Based on the obtained results, soil reaction rate, absorbable potassium, relative humidity, organic carbon, clay and soil carbon storage had significant differences among the four stands (P < 0.01). Alnus subcordata and Acer velutinum showed the highest amount of carbon storage compared to Cupressus sempervirens and natural forest stand. The difference observed in the amount of soil organic carbon in the studied stands depended on the different capabilities of tree species in restoring the soil ecosystem. The planting of broadleaf species resulted in more carbon storage in the short term than coniferous species, because broadleaf tree species increase litter production and nutrient return, making them more effective in restoring degraded forest soils. This is due to faster leaf decomposition, higher nitrogen content and lower C/N ratio, while the presence of resinous and phenolic substances in coniferous leaves negatively affects the decomposition of their litter.

In summary, this research showed that reforestation with broadleaf species in various areas of the region significantly impacted the soil carbon stock and carbon storage potential based on the type of tree species. Particularly, broadleaf species such as Alnus subcordata and Acer velutinum played a crucial role in increasing the amount of carbon stored in the soil of the studied region.

Plant leaves react to environmental changes with high adaptability. This study investigated the morphological characteristics of Persian oak (Quercus brantii) and wild pistachio (Pistacia atlantica) leaves from 15 forest sites in Ilam province at an elevation range of 1000 m (from 1111 to 2048 m a.s.l.). At each site and for each tree species, five healthy individuals and five healthy and mature leaves were collected from the outside and middle of the crown. The leaf area index, petiole length, main vein length, leaf circumference, blade length, blade width, and the number of leaf margin dentations were measured. The data were analyzed based on the nested research design, and the means of the studied traits were compared using the LSD test. In the Persian oak trees, the results showed that the petiole length (1.72 cm), leaf circumference (20.23 cm), leaf length (8.17 cm), leaf width (4.43 cm), and leaf area (28.16 cm2) at higher elevations had higher averages than at lower elevations. However, the number of leaf left and right dentations were 12.26 and 12.47, respectively, indicating higher average weight at lower altitudes. In pistachio, all measured characteristics like petiole length (0.46 cm), leaf circumference (13.98 cm), leaf length (5.53 cm) and leaf width (3.29 cm), and leaf area (12.31 cm2) at higher elevations had higher averages than the lower elevations as 0.24 cm, 12.26 cm, 5.18 cm, 3.0 cm, and 10.85 cm2. The significant intra-population changes strengthen the idea of intra-population morphological diversity for oak species at the regional level and even in Zagros to some extent. Among the studied features, those that are less sensitive to environmental changes can be used as distinguishing features for species separation.

Different fertilizers such as green, animal, chemical, biological and biochar are used in different nurseries to improve germination and growth. The purpose of this research is to investigate the effect of soil conditioners on the germination rate and percentage of Fraxinus excelsior seeds in forest nurseries. This experiment was carried out in Nursery Lajim, located in Sarjangalbani Kaslian, General Department of Natural Resources and Watershed of Swadkoh city. In this research, 20 soil conditioning treatments include rice husk to amount of 0.5% and 1% of soil volume, rice husk biochar to amount of 0.5%, 1% and 2% of soil volume, 150 and 300 grams of cow manure, minimum and maximum chemical fertilizer (minimum chemical fertilizer for super triple phosphate 0.6 grams, for ammonium sulfate 0.45 grams and potassium sulfate 0.45 grams and chemical fertilizer for triple superphosphate 1.2 grams, for ammonium sulfate 0.9 grams and potassium sulfate 0.9 grams) and the control treatment was considered with three repetitions. The seeds selected for the experiment were cultivated in the appropriate soil depth, by observing the first young seed on the 10th of April, counting of seeds has started. The quality of seed germination was leaf emergence. For statistical analysis, after checking the normality of the data and the homogeneity of variances using the Shapiro Wilk and Loon tests at the 95% probability level, one-way analysis of variance was used. If the data were significant, comparisons were made using Duncan's test. The results showed that the effect of soil conditioners on the speed and percentage of seed germination has a significant effect. The highest germination rate and percentage were observed in the treatments of 1.25% cow manure and 1% rice husk, 1% maximum chemical fertilizer and rice husk, 2% rice husk biochar and 1% rice husk biochar, and in general, the use of these materials had the greatest effect on seed Fraxinus excelsior. it is suggested to use organic materials such as rice husk and cow dung to increase the germination of Fraxinus excelsior seeds in forest nurseries.

Current study reviews effect of the Darabkola forest plant communities on Carbon sequestration in soil and Above Ground Biomass (AGB). It compared five natural communities, including Parrotio persicae-Carpinetum betuli, Zelkovo carpinifoliae-Quercetum castaneifoliae, Solano kieseritzkii-Fagetum orientalis, Aceri velutini-Parrotietum persicae, Euphorbio amygdaloidea-Fagetum orientale, and one Maple plantation stand. Sampling was done using systematic randomized with 400×400 meters dimensions. After removal of marginal points, soil samples were collected from center of 163 plots with 20×20 meters dimension. Results of ANOVA, mean comparison, and PCA showed that the highest soil Potassium belongs to the plantation stand (336.96±18.97), while the least one, belongs to Solano kieseritzkii-Fagetum orientalis (160.25±10.75). On the other hand, soil Phosphorus was the highest in the Aceri velutini-Parrotietum persicae (4.65±0.55), and it was the lowest in Solano kieseritzkii-Fagetum orientalis (1.95±0.14). Aceri velutinid-Parrotietum persicae (34.80±2.08) and Solano kieseritzkii-Fagetum orientalis (22.73±1.22) had the highest and the lowest soil moisture content, respectively. However, the study proved that different communities did not affect soil sand percent and carbon sequestration. Zelkovo carpinifoliae-Quercetum castaneifoliae (242.82±23.22) had the highest, and plantation stand (54.78±5.55) had the lowest carbon sequestration in AGB.

This study was conducted with the aim of investigating the effects of fire on the vegetation in Shanderman forests (Guilan province). For this purpose, 60 sampling plots of 400 m2 were taken in a random-systematic Method in the areas of burned and control. The plant species present at the level of the samples were collected and identified, and their Life forms determined based on the Runkaeir's method. The results showed that 60 plant species were identified in the studied forest, 13 species (22%) only in the fire area, 5 species (8%) only in the control area, and 42 species (70%) were observed common in the both regions. The highest frequency belonged to Rosaceae and Poaceae families. In the study of the life forms of plant elements in the burned and control area, phanerophytes and hemicryptophytes were the most present in both regions. The results of the investigation of plant biodiversity indicators showed that the values of species diversity indicators in the burned area were higher than in the control area. DCA analysis showed that the composition of the vegetation in the burned area is not significantly different from the control area. Therefore, it can be concluded that after 12 years of the fire, the vegetation composition of the area has been restored and has become the same as the control area.

One of the most important causes of disability in the elderly is skeletal-muscular disorders. The present study was conducted to determine the prevalence of musculoskeletal disorders (MSDs) and their relationship with some related factors in the elderly.

This cross-sectional study was conducted on 232 elderly residents of a nursing home in Rasht, using convenience sampling based on the inclusion criteria. The research instruments included demographic information, developed Nordic questionnaire, and visual pain scale. Data analysis was performed with SPSS 16 and using descriptive and analytical statistics.

The findings showed that 51.72% and 48.28% of the samples had mild and moderate musculoskeletal pain, respectively. All samples (100%) had MSDs in multiple areas of the body. The most disorders were related to the neck (51.72%) and knees (40.51%), and the least to the elbows (20.68%) and heels (25.86%). The prevalence of these disorders was higher in males, illiterate and low educated individuals, with an agricultural history, deceased spouses and obese individuals than others. There was a significant relationship between the prevalence of MSDs with age (P=0.018, X2=0.245) and body mass index (P=0.02, X2=0.935) (p<0.05).

The results of the present study may be of interest to managers and health officials to plan and take necessary precautions to reduce pain and MSDs and improve the quality of life of the elderly.

One of the consequences of destruction and fragmentation of forest ecosystems in the north of Iran is the creation of an edge effects and changes in the composition and biodiversity of the understory cover. Therefore, the purpose of this study was to investigate the edge effects due to rural roads, forest roads, rural development and recreational areas on the composition and biodiversity of understory cover in the Zarin Abad forests of Sari City. In order to conduct this research, in each of the four mentioned areas, three transects were considered in parallel with a distance of 100 meters. On each transect at intervals of zero, 50, 100 and 150 meters, sample-parts of 400 square meters were landed and in each sample plot, a list of all plant species and their abundance (percentage of canopy cover) were recorded. The results showed that the sample plots in the distances of 50,100 and 150,100 had higher Jaccard index and the 0,150 sample plots had lower Jaccard index. DCA analysis indicates that the sample plots at zero and 150 m distance from the road were different from other distances. The results of the present study showed that all the studied edge effects had significant effect on the richness, diversity and composition of vegetation, which these effects increased with the distance from the edges. Among the studied edge effects, the forest road had the least effect and the recreation area had the most effect.

The aim of this study was to investigate the effects of rice husk, rice husk biochar, cow manure and chemical fertilizers on the morphological and physiological characteristics of coliseum maple (Acer cappadocicum Gled.) and ash (Fraxinus excelsior L.) seedlings. A total of 60 pots were considered for nine modifying treatments and nursery soil with three replications in a completely randomized design in Lajim nursery located in Savadkuh county, north of Iran. Results showed that different treatments had significant effects on some morphological characteristics of ash. The highest diameter, height, stem length of this species were observed in 150 g of cow manure treatment and the highest dry leaf weight was observed in 300 g of cow manure treatment. Different treatments had significant effects on the height of first stage, leaf area, volume, cross section and length of roots, leaf dry weight and stem volume of coliseum maple seedlings. The highest height in first stage of this species was observed in the control and the highest root volume was observed in the treatments of 300 and 150 g of cow manure and 2% of rice husk treatments. The highest root cross section, root length, leaf dry weight and stem volume of coliseum maple seedlings were observed in 300 g of cow manure treatment and the highest mean leaf area was observed in 150 g of cow manure treatment. In addition, no significant difference was observed in chlorophyll content and photosynthesis of different treatments. In general, the obtained results show that the use of cow manure compared to chemical fertilizers and biochar has a better function in increasing the growth of Fraxinus excelsior and Acer cappadocicum seedlings during a period of plant growth in the nursery.

The root of trees is one of the most important living materials for stabilizing and reinforcing the cut and fill slopes of forest road. This study was conducted to investigate the tensile strength of tree species according to changes in lignin, cellulose and root extracts content.

Darabkola forest in the southeast of Sari-Iran was selected for this study. To determine the tensile strength of tree roots, root samples from tress including the beech, hornbeam, alder, Zelkova carpinifolia, Persian Ironwood and oak were collected by soil profile trenching method and then the test of tensile strength was performed. The amount of lignin, cellulose and ash for the roots of different tree species was also measured in the laboratory. One-way anova was used to compare the means of roots tensile strength and also multivariate analysis was used to classification of species based on cellulose, lignin, ash and other extracts content.

The results showed that in beech, alder and Persian Ironwood, the measured rates of lignin were higher than cellulose levels. While in the Zelkova carpinifolia, the amount of cellulose was higher than others parameters, in beech and alder species (with higher lignin rate) the means of tensile strength was recorded less than other species, and for oak and hornbeam with higher cellulose levels, tensile strength was recorded higher than other species. The results of multivariate analysis based on tensile strength and numerical values of root decomposition showed three groups with high adaptability percentage (alder-beech, hornbeam-Zelkova carpinifolia and Persian Ironwood-oak).

According to the results, investigating the amount of lignin and cellulose in roots of different species as well as discriminant analysis with consideration of different factors can be a scientific method to select best species for soil bioengineering projects.

Reforestation stands can effect on diversity of plant species and soil characteristics of an area. In this study, the effects of 25-year-old reforestation stands with Acer velutinum Bioss., Alnus subcordata C. A. M. and Cupressus sempervirens species on plant biodiversity, understory vegetation and some physico-chemical of soil properties were studied compared with natural forest (Carpinus betulus and Fagus orientalis) in the Kolet forests of Mazandaran province.

In each reforested stands and natural forest, ten plots (2020 meters) were selectively sampled in transects which were 100-m stretches systematically. Then, the list of all herbaceous species and their abundance (cover percentage) was recorded. Also, in each sample plot, a soil sample was taken from the four corners and its center at a depth of 0-15 cm, then these samples were mixed together and a composite sample were taken to study the physic-chemical characteristics of the soil (bulk density, soil texture, acidity, electrical conductivity, organic carbon, total nitrogen, absorbable phosphorus and potassium). The indices of richness (Margalf and Menhenic), evenness (Shannon-Wiener) and diversity (Simpson and Shannon-Wiener) were also studied.

The results showed that reforested stands were significantly different from natural forest (control) in terms of soil reaction rate (P <0.05), potassium, clay and relative soil moisture (P <0.01). Also, the amount of acidity and absorbable potassium reaction in Acer velutinum Bioss mass (6.99, 904.51 mg kg-1) was the highest and lowest in natural mass (6.18, 557.57 mg / kg). It was observed that the highest percentage of clay in natural mass (43.57%) and the lowest percentage in Alnus subcordata mass (39.32%) and the relative moisture in Acer velutinum Bioss mass (40.78%) was the highest and It has the lowest value in Cupressus sempervirens mass (20.12%). But other soil variables did not show significant differences with natural forest. Margalf and Manhenic richness in the four reforestation stands was significantly different (P <0.05). The diversity indices (Simpson, 0.58 and Shannon-Wiener, 1.26) and the richness (Margalf, 2.00 and Mannick, 1.57) were higher in the natural forest than four reforestation stands and the evenness index (Shannon-Wiener, 0.82) showed the highest value in the Cupressus sempervirens stand. Multiple regression of soil variables with the first and second axes of DCA analysis indicates that only potassium has been effective in the separation and differentiation of vegetation in the area and the four studied stands can be distinguished in terms of understory vegetation.

In general, the results of the present study showed that the richness indices of understory vegetation species as well as the characteristics of moisture, soil reaction and adsorbable potassium changed under the influence of reforestation and according to DCA analysis is the most important component in mass segregation. Potassium is an absorbable plant. Also, the study of biodiversity indices showed that the diversity and richness indices were higher due to the fusion of species in the natural massif (Carpinus betulus and Fagus orientalis) compared to the reforested massifs of conifers (Cupressus sempervirens). In other words, the results show a greater protective role of broadleaf stands (Acer velutinum Bioss and Alnus subcordata C.A.M) and natural stands (Carpinus betulus and Fagus orientalis) than needle stands (Cupressus sempervirens) for richness and diversity of understory vegetation species and sustainable maintenance of communities the underside is in the Kolet area.

Species diversity is a combination of two interrelated components of species richness and evenness. The first component is the species richness, which is related to the number of species in the sampling unit; The second component is evenness, which refers to the distribution of species in the site. One of the important problems of these indicators is not determining the contribution of these two components in the diversity index value. An effective method that has been developed for this purpose is called SHE. The aim of the was to investigate the contribution of diversity of understory species in four natural stands, Acer velutinum Boiss, Alnus subcordata C. A. M. and Cupressus sempervirens. var horizontalis afforestation in Colet forest.

In this research, using 40 square plots with an area of 400 square meters, which were selectively sampled in the study area. Then, the list of all herbaceous species with its cover percentage were recorded by Vandermarel criteria. Woody species were counted in each sample plot. The grass and wood cover data were organized in Excel and PAST software for analyzing of richness (number of species, Margalf richness and Menhenick richness), evenness (Shannon-Wiener), diversity (Simpson and Shannon-Wiener). The normality and homogeneity of the data was evaluated using Kolmogorov-Smirnov and Leven test, respectively. SHE analysis was used to determine the contribution of each component of richness and evenness.

The results of comparing the mean of different diversity indices related to herbaceous species showed that the four studied stands (natural, Acer velutinum Boiss, Alnus subcordata C. A. M. and Cupressus sempervirens. var horizontalis) have significant differences in terms of richness (Margalf and Manhenic) (P <0/01). The results of classification of plants in terms of biological form by Raunkiaer method also showed that hemicryptophytes have the highest abundance in the study area. Also the SHE analysis of richness and evenness components for woody regeneration species in the Colet area showed that the evenness of the trend is constant between the four stands and the richness index in the Cupressus sempervirens and natural stands were fluctuating and its trend has an increase shape. In the Alnus subcordata stand, the evenness and richness index had the same contribution in determining the diversity of herbaceous species and woody regeneration in this region. In addition, SHE curve showed that the richness curve (LnS) and the uniformity (Ln E) do not change with each other, and the change in the richness curve is greater than the evenness. This indicates a greater contribution of richness than evenness in contribution of determining the diversity of data related to herbaceous species and woody regeneration. In fact, this showed that with the increase in the number of samples, only rare species were being added to the list of herbaceous and woody species.

In general, the results of the present study showed that the diversity of herbaceous species due to species composition in the natural stand had the highest value in this region. Also, richness and diversity of woody species in natural stand and broadleaves reforestation stands were higher than coniferous reforestation. Therefore, reforestation with broadleaves species has a positive effect on the diversity in the region. Also, the effective factor on the diversity indices in the four stands was the richness component (Ln S), which means that severe changes and fluctuations in plant species and their composition have been observed.

This study focused on vegetation classification of Darabkola forest in the middle part of Hyrcanian forests in north of Iran. For this purpose, 139 releves were sampled using systematic- selective method in 400 m grid dimensions by the consideration of indicator stands concept. Based on modified TWINSPAN method and Braun-Blanquet phytosociological method, five associations (Parrotio persicae-Carpinetum betuli, Zelkovo carpinifoliae-Quercetum, Solano kieseritzkii-Fagetum orientalis, Aceri velutini-Parrotietum persicae and  Euphorbio amygdaloidae-Fagetum orientale) and four sub-associations (Zelkovo carpinifoliae-Quercetum castaneifoliae subasso a typical subasso Quercetosum, Zelkovo carpinifoliae-Quercetum castaneifoliae subasso Fagetosum orientale, Aceri velutini-Parrotietum persicae subasso Carpinetusum betuli and Aceri velutini-Parrotietum persicae subasso Pteroetosum fraxinifoliae) were distinguished. Demonstration of plant communities along the first two axes of detrended correspondence analysis (DCA) showed that these associations had almost distinct pattern. Also, results of multiple regression of topographic factors with the two first ordination axes of DCA indicated that elevation was the most important topographic factor in distribution of the associations in the Darabkola forests. In addition, the results of this study can lead to the more efficient management and better protection of Darbakla forest.

The goal of this study is to evaluate the quality of numerical methods (Phi fidelity and indicator value indices) and non-statistical (constancy ratio and total cover ratio indices) in determining the indicator species of Beech plant communities in the eastern Hyrcanian forests. For this purpose, six ecological groups were first classified using two-way indicator analysis or TWINSPAN. Then, by using sum of the indicator value/association indices or TFVI, as a similarity index for assignment of the plot to the plant communities, with emphasizing the result of species and plant communities association (based on 10 algorithms), the groups were reclassified. Evaluating the compatibility of the results of each classification algorithms with the initial plant communities which have been classified by Braun-Blanquet synoptic table showed that reclassification of sample sites by using TFVI when is derived by group-equalized and incidence-based phi index (84%) and constancy ratio method (82%) showed the highest adaptability with the initial plant communities respectively. Totally, the results of this research revealed that group-equalized and incidence-based phi fidelity and constancy ratio indices have the most priority in assessing the association between species and groups of sites or in determining the diagnostic species of plant communities than the other association indices.

Theoretically, graphene quantum dot (GQD) has proved to feature in severalimportant applications during recent decades. Generally, quantum dot, which isof nano-scale size is comparable to the size of atoms and molecules, havingdifferent properties from the bulk of the same materials. In Nano scales, theelectrical, optical, thermodynamic, and mechanical properties of samples aredirectly related to the number of atoms constituting the sample, regarding sizeand shape (type of edge, forms, and dimensions). In this paper three differentstructures of GQDs with zigzag edges (Benzene, Coronene, andCircumcoronene) have been considered and simulated using the DFT theory byapplying PBE functional in order to extract the thermal energy, electronicenergy, heat capacity, polarizability, and entropy of each structure. Themodification of each property with respect to the number of atoms in the GQDare investigated, linear and nonlinear variations of these properties with respectto the atom number are observed. Comparative study of Raman spectroscopybetween PBE and B3LYP functionals is studied for each size of the consideredGQDs. Also, revolution of the G peak in each case has been separatelyinvestigated. All calculations are done by using the Gaussian 09W softwarepackage based on 3-21G Gaussian basis sets.

The Increase in studies of beta diversity has led to several measures and methods. The variety of theses indicators cause their use in confusion. The aim of this study was to evaluate and determine the relationships between 18 different beta diversity indices based on presence and absense data. For this purpose, Buxus hyrcana database in Golestan and Mazandaran provinces was used. Clustering results showed that these 18 indices classified into 4 distinct groups with similar performance. Evaluation of clustering results by Detrended correspondence analysis (DCA) analysis showed that the indices of the four groups of cluster analysis can be separated into three distinct groups. From basis of combined results of discriminant analysis and Braun-Blanquet method, three vegetation units were recognized, which had 64.1 percent coincide with phytosoicilogical plant communities in Braun- Blanquet method. Also, among of 18 beta diversity indices included in the discriminant analysis, only Bm, Bc, B-2, Brlb, Bco, BI and Be were added in three functions. Among these 7 indices, them, Bm, Bc, BI and Be had a high canonical correlation with the three discriminant analysis functions. totally, the results of this study showed that many beta diversity indices based on presence and absense data have similar performance, and the numerical values of beta biodiversity indices are a good criterion for identifying Buxus hyrcana plant communities, provided that species turnover in these plant communities being high.

In this paper, we evaluate quality of several similarity indices for assignment of new releve to vegetation units, using geometric and non-geometric based evaluators. For this purpose, Buxus hyrcana dataset (437 releves) that belong to Mazandaran and Golestan provinces in Hyrcanian forests was used. 11 vegetation units as a primary groups produced by combination results of TWINSPAN, Modified TWINSPAN and cluster analysis. All of 437 releve were re-assigned to 11 primary groups by six similarity indices indices that consider Phi fidelity index. With the exception of Calinski and Uniqueness evaluators, classification resulting from TPFI similarity index had the highest values of evaluators. Results of PCA analysis showed that ISA evaluator as a non-geometric evaluator with two geometric evaluators consist of PBC and PARTANA are the most important evaluators. Totally, the results of this study revealed that among six similarity indices, TPFI to be an effective one for assignment of new releve to vegetation units.

Cold stratification is widely used to break dormancy of ash (Fraxinus excelsior L.) seeds. In this study, two groups of seedlings produced by two treatments of ash seeds, one and two-years cold stratification of seeds were investigated with three replications in a completely randomized design in samples of one m2 per plot. Some quantitative characteristics of seedlings including collar diameter, leaf area, stem length, root length, crown height and its biomass and leaves chemical characteristics including organic carbon, nitrogen, phosphorus, potassium and relationship between carbon to nitrogen are examined. The results showed that seedlings density from the two-years old seeds (average of 157.67 seedlings per m2) was significantly higher than that of one-year treatment seeds (average of 61.67 seedlings per m2). Also significant difference between two stratification treatments was recognized for collar diameter, crown diameter, crown height, total height, root length and leaf area index; which were higher values in two years’ cold stratification treatment. Among the chemical characteristics of leaves, only potassium content showed significant difference which was higher in the two years’ cold stratification treatment. In general, we conclude that cold stratification on seed of ash for two years ensure the successful production of ash seedlings in nurseries.

Aboveground vegetation were sampled by 30 plots of 400 m2 during two periods of March and June. Seed bank flora was studied using seedling emergence method from basis of 240 soil samles (30 plot×4 replication×2 depths of 0-5 and 5-10 cm) which had been hammered by a hollow 400 cm2 metal frame. The floristic results in aboveground vegetation revealed 66 plant species belonging to 58 genera and 38 families, while a total of 103 species, 90 genera and 48 families were represented in the soil seed bank. Lamiaceae, Rosaceae, Poaceae (6 species) and Asteraceae (4 species) in the extant vegetation but in seed bank part Poaceae (11 species), Asteraceae (8 species), Lamiaceae (6 species), Scrophulariaceae, Cyperaceae and Fabaceae (5 species) were the most important families. Results also showed that Phanerophytes (33%) and Euro-Siberian (34%) were the most important biological spectrum and phytochorion respectivly in the aboveground vegetation, whereas therophytes and pluriregional regions elements (31/5%) were the most in the seed bank floras. From total of 119 plant species, the proportion of species that presented only in the aboveground vegetation, only in soil seed bank and in both of them were 16, 53 and 50, respectively. This condition confirms low similarity between above-ground vegetation and persistent soil seed bank and it also reiterate the importance of soil seed bank study for introducing more accurate capacity of plant biodiversity.

This study was investigated the above-ground vegetation and soil seed bank flora in three site of Albizia julibrissin Durazz. In Hyrcanian Lowland Forests (including Haloomsar, Anjilisra forests and Sisangan Box tree (Buxus hyrcanus Pojark) reserve). Aboveground vegetation was sampled by 68 plots of 400 m2 during late June and seed bank flora was studied by seedling emergence method. The result showed that there were 66 plant taxa belonging to 59 genera and 38 families in the extant vegetation of the studied eareas, while a total of 93 species, 82 genera and 48 families were represented in the soil seed bank.Lamiaceae, Poaceae and Rosaceae with 5 species (7.6%) were the most frequent families in the above-ground vegetation while in soil seed bank Asteraceae with 12 species (12.9%), Lamiaceae with 6 species (6.5%) followed by Cyperaceae, Fabaceae and Poaceae with 5 species (5.4%) were the most important families. Results also showed phanerophytes with 37.9% (25 species) and Euro-Siberian with 42.4% (28 species) in the Above-ground Vegetation floras and Hemicryptophytes 32.3% (30 species) and pluriregional regions elements 28% (26 species) were the most important biological spectrum and phytochorion in the seed bank floras, respectivly.From total of 118 plant species, the proportion of species that presented only in the above-ground vegetation, only in soil seed bank and in both of them were 25, 52 and 41, respectively. This condition not only explains low similarity between soil seed bank and above-ground vegetation and it also showed the importance of soil seed bank study for introducing more accurate capacity of plant biodiversity. our result also showed that Albizia julibrissin Durazz with the average seed density of 270 seeds/m2 are attending in 61% of total seed bank samples which it emphesizes the role of its seed bank as a suitable source for natural restoration of Albizia julibrissin in the Hyrcanian Forests

This study intends to assess the application of Cocktail method in the classification of large vegetation databases. For this purpose, Buxus hyrcana dataset consisted of 442 relevés with 89 species were used and by the modified TWINSPAN. For running the Cocktail method, first primarily classification was done by modified TWINSPAN, and by performing phi analysis in the groups resulted five species were selected which had the highest fidelity value. Then sociological species groups were formed by examining co-occurrence of these 5 species with other species in the database. 21 plant communities belongs to 6 variant, 17 sub associations, 11 associations, 4 alliance, 1 order and 1 class were recognized by assigning 379 releves to the sociological species groups by using logical formulas. Also, 63 releves by the logical formula were not assigned to any sociological species groups, by FPFI index were assigned to the sociological species groups which had the most index value. According to 91% classification agreement with Brown-Blanquet classification and Cocktail classification, we suggest Cocktail method to vegetation scientists as an efficient alternative of Braun-Blanquet method to classify large vegetation databases.

After over five decades of establishing plantations in Chitgar Forest Park in Tehran, no study has yet been carried out on the soil seed bank in this region. This study aimed to investigate the composition of above-ground vegetation and soil seed bank. Therefore, 30 releves were established with 450m2 area each. For sampling soil seed bank within each releve, two samples were randomly collected by hammering a 400 cm2 into the soil to a depth of 5-10. Following this, the soil seed bank was estimated using the seedling emergence method. All in all there were 22 families and 62 species in above-ground vegetation and 29 species from 13 families were identified in the seed bank. All species in the soil seed bank were present in the above-ground vegetation. The results also showed that the above-ground vegetation included a higher species richness than the soil seed bank. High similarity of the soil seed bank and above-ground vegetation showed that the soil seed bank has the potential for reclamation of above-ground vegetation, but the lack of tree species in the soil seed bank hampers the practicability of the reforestation with an emphasis on seed germination of the soil seed bank. Furthermore, because of the structure and the type of the previous above-ground vegetation across the test site, the natural tendency of the area is towards the non-forest species.

There are several available indices to assess the group associations between species and sites in order to identify diagnostic species. In this study, we introduced 11 indices of species-site groups and evaluated their quality by means of a TFVI model and four numerical criteria, including average positive fidelity, sharpness, uniqueness and crispness based on of 168 releve of Buxus hyrcana habitats. We used a modified TWINSPAN classification of 168 releve (Nine vegetation community/site groups) to determine the species fidelity value. The results showed that new classification obtained from assigning releve using TFVI model based on IndVal, UbinB and Ochiai indices returned the highest values of the fourfold criteria in evaluating classification quality. Moreover, they achieved higher qualities compared to other indices. Also results of cluster analysis and PCA diagram showed that 11 species-site groups’ association indices can be divided into four groups. The scatter plot of association indices along two first axes in PCA (eigenvalues 0.556 and 0.365, respectively) explained 92% of total variation, and species fidelity values based on IndVal and Ochiai indices were similar and noticeably different with other indices. Finally, the results of this study revealed that IndVal and Ochiai indices have the most priority in determining diagnostic species of vegetation communities compared to the other examined association indices.