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Extended Abstract Background: In contemporary times, the increasing population growth in large urban areas, industrial development in these cities, and the need for expanding urban green spaces and green belts have drawn the attention of managers to the use and cultivation of multipurpose tree species more than ever before. In many advanced countries, the use of chemical fertilizers has been discontinued in urban green spaces, parks, agriculture, and horticulture. The major reasons for this include undesirable environmental effects, disruption of soil chemical balance and structure, disruption of the ecology of plant and animal communities, and pollution of freshwater bodies. For this reason, the utilization of various organic fertilizers has been highlighted as one of the important strategies in improving horticultural and agricultural production and reducing the risk of environmental pollution, especially pollution of surface and groundwater resources. Humic acid (HA) is among the main types of organic fertilizers and a type of stabilized organic acid derived from the main compounds of humus, considered one of the most abundant organic compounds in nature. The use of HA for plants can directly and indirectly promote better plant growth, thereby increasing production levels and improving crop quality. Therefore, the present study aimed to assess the possibility of enhancing the growth and viability components of white mulberry seedlings as the most commonly used tree species for planting in the green belt of Mashhad using HA fertilizer and animal manure. Methods: For this research, two-year-old and uniform-sized mulberry seedlings were prepared as bare-root. Then, they were transferred to prepared beds in the green belt nursery of Mashhad for planting in pits with planting distances of 1.5 × 1.5 m in a completely randomized design. In five separate experimental plots, the nursery soil was thoroughly and uniformly mixed with animal manure. Subsequently, HA fertilizer in liquid form (at 50 and 300 mg/l) was mixed with the soil in two plots in addition to the animal manure. In the other two plots, foliar spraying at 50 and 300 mg l-1 on the leaf surfaces of the seedlings was carried out at the beginning of the growing season. Only animal manure treatment was considered for the seedlings in the fifth plot. Ten seedlings were selected for each treatment as replicates for examination. The seedlings were irrigated uniformly throughout a six-month growing period for measurement purposes. The growth and physiological characteristics of the seedlings, including plant height, collar diameter, root length, leaf and branch numbers, dry weight of aerial and root parts, gas exchange rates, photosynthesis rate, and seedling survival, were measured and statistically compared after 6 months of applying the treatments. To measure biomass, the seedlings were carefully removed from the soil, and the soil was washed from around the roots, followed by counting the number of branches and leaves. Each seedling was then divided into two parts of roots and stems, which were dried at 70 °C for 48 h and weighed using a digital scale. Finally, the data were analyzed in a completely randomized design, and their means were statistically compared using Tukey's test. The gas exchange rates (stomatal conductance) and photosynthesis rate in outdoors and under natural conditions of temperature, light, and relative humidity were measured using a portable device for gas exchange measurements. For this purpose, 3-6 mature leaves were selected from each replicate. All measurements were conducted between 9 am and 12 pm on a sunny day with a light intensity of 1400 µmol m-2 s-1. Results: The HA treatment added to the soil at a concentration of 300 mg/l resulted in the highest average values of the variables, namely the highest values of radial growth (3.2 mm), sapling height growth (35.1 cm), number of leaves (45), number of branches (16), dry root weight (31.3 g), and shoot weight (38.1 g). A comparison of physiological variables, such as photosynthesis intensity (14.5 μmol m-2 s-1) and stomatal conductance rate (0.23 mol m-2 s-1), revealed that the treatment with 300 mg/l of HA added to the soil led to the highest values. Subsequently, the treatment of 50 mg l-1 of HA added to the soil and then foliar spraying with an HA solution of 300 mg l-1 showed better effects than the other treatments. Overall, increasing HA in the soil resulted in better performance than foliar spraying on the leaf surface of white mulberry seedlings. Animal manure created the lowest averages in all evaluated variables. Conclusion: The positive effects of HA on plant growth and biomass are attributed to its ability to increase water and nutrient absorption by plants, as well as its pseudo-hormonal effects on plants. Based on the results of the present study, HA application positively influenced growth characteristics, photosynthesis intensity, and biomass increase (variables such as leaf number, branch number, sapling length growth, radial growth, root growth, and aerial parts growth). Therefore, adding HA fertilizers to the soil during mulberry planting is highly recommended in urban green spaces, horticulture, and urban green belts.

Extended Abstract Background: 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. Methods: 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. Results: 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. Conclusion: 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.

Iran’s Hyrcanian forests are part of the temperate forests and have survived since Tertiary. These forests have experienced severe damages in recent decades because of socio-economic issues such as overgrazing. This study aimed at investigating the Nurse-protégé interaction and the impact of understory shrub species on the regeneration of the Hyrcanian main tree species in Kheyrud Forests. Filed sampling was carried out using the random-systematic method. Regeneration and their features under and outside of the canopy of shrub species, as well as some environmental variables were recorded in strip plots. According to the results, the canopy cover percentage of 25-50% provides the best regeneration protection efficiency for the six nurse shrub species. Overall, regeneration density was found to be higher outside the canopy area of the shrub species than beneath their canopy area; however, regeneration under the shrub species caused higher mean height and age. Moreover, the mean cover and the depth of the litter under the shrub canopy were significantly higher than that of outside the canopy area. Although the shrub species allow more durable and complete development of seedlings by providing protection against grazing, suitable conditions for seed germination and seedling growth may not be provided because of high litter depth and insufficient sunlight due to the massive canopy of trees as well as nurse shrubs’ dense foliage (especially, evergreen understory species).

Canopy gaps play an important role in forest ecology helping to preserve biodiversity, influence nutrient cycles, maintain the complex stand structure, and also they substantially contribute to regeneration of forests. To survey the characteristics of canopy gaps in the Hyrcanian forests of Iran, three main old-growth and intact stands were studied. For each canopy gap, two parameters were measured: the length (L) as the longest distance within the gap and the width (W) as the largest distance perpendicular to the length. The gap maker (DBH≥20 cm) was considered to be a tree from the upper tree layer whose death caused an opening in the canopy. A total of 89 canopy gaps were studied in three old-growth stands (48 gaps in hornbeam-ironwood, 21 in hornbeam, and 19 in beech-hornbeam stands). The given canopy gaps cover 5.4% of the land area with an average of eight gaps per hectare. The mean size of the canopy gaps were 291, 353 and 565m2 for hornbeam-ironwood, hornbeam, and beech-hornbeam stands, respectively. Frequency distribution of the gap sizes the mentioned three forest stands showed a lognormal distribution. The number of gap makers ranged from one to eight with a median of 4.5. Amongst the studied 261 gap makers in all canopy gaps, 61.2% belonged to hornbeam-ironwood stand. Also, there were canopy gaps formed by one to four gap makers within the three forest types, while gaps formed by five, six and eight gap makers were only observed within hornbeam stand. The results showed that the characteristics of the canopy gaps were different in terms of the composition, complexly of structure, environmental characteristics, size, number and species of gap makers in different forests. As a whole, hornbeam-ironwood stands present in lower altitudes, are more susceptible to wind-throw and create smaller gaps but more gap makers.

Oriental beech (Fagus orientalis Lipsky) is the most important and valuable industrial wood species in the Hyrcanian forests in the north of Iran mainly used for furniture, veneer, composite, and papermaking industries. The present research was conducted in 2014 aimed at investigating the physicochemical changes of the felled oriental beech stumps over a 2-25 year period, and likewise the feasibility of using the given stumps as an alternative resource for wood pulp production. To do so, the effects of in-situ decay of beech stumps on their physical (wet and dry weights of wood, wet apparent density, and dry apparent density) and chemical (cellulose, hemicellulose, lignin, extractives, and total mass of carbohydrates) properties over a 2-25 year felling period were studied. The effects of the given decay period were also studied on the obtained Kraft pulp yield and Kappa number. The results indicate that the wet and dry apparent densities as well as the wet and dry weights of the wood samples decreased over the study period. Also, the results show that approximately 30% of the total mass of carbohydrates was degraded by the ambient fungi over the initial two years of felling, whereas the same property was reduced by 60% after 25 years. The Kraft pulp yields obtained from 2- and 25-year decayed stumps were 22.5% and 8.4%, respectively. The fungal degradation of wood chemical compounds could considerably reduce pulp yield and Kappa number by 62.8% and 74.2%, respectively. The results of a stepwise multivariate regression model evidence that cellulose not only affects the Kappa number but also owns a greater share (vs. lignin) in modelling the Kappa number. This reveals that the intensity of cellulose degradation, due to fungal exposure, is significantly higher than that of the other components of beech stumps in the studied forest area.

Introduction: The diversity and abundance of soil fauna in the forest have an important role in nutrient cycle, and destructive factors (e.g., fire) would cause a disturbance in the balance of soil communities. In the current study, the effect of fire on biodiversity, richness, abundance, fresh biomass and trophic levels of soil-dwelling invertebrates in Galandroud forest were investigated and discussed. Material and methods: This research was conducted in districts 20 and 21 of series 11 from watershed 48 of Natural Resources and Watershed Management Department of Nowshahr. Ten 30×30 cm quadrates with 30 cm depth were randomly placed in both fired and control forests (20 quadrates in total) across two distinct using hand-sorting methods. The soils were collected into a pan, and transferred to the laboratory for identification and measuring the fresh biomass after separating the fauna into plastic bags. Then, the fresh biomass of soil animals was separately measured using a digital balance (with an accuracy of 0.0001 g) and then identified at family and order levels. The PAST software was used to calculate the dominance, biodiversity and richness indices of the soil fauna. Statistical comparisons were done with independent sample t-test using SPSS software. Moreover, the trophic levels of the soil fauna were determined and the abundance and biomass of each five main trophic groups were investigated within two fired and control forests. Results and discussion: Among the identified macrofauna, the earthworms were the most abundant. The abundance of almost all species was more in the control forests rather than the fire-burned ones, except for coleopteran beetles and the ants. The total biomass of trophic levels did not show any significant difference between the two forests, while it’s amount in the burned and control forests was 2.35 and 1.70 g.m-2,respectively. Among detritivore biomass, the biomass of earthworms and coleopteran beetles increased, while it decreased for millipedes, slaters, and Diplura in the burned forests compared to the control. According to the similar studies that have been done so far, most faunal assemblages have shown a negative response to the fire in the short term, and then their populations revived or even increased compared to the control area. Conclusion: The results revealed that almost all indices did not show a significant difference between fired and control forests after 5 years, with an exception for evenness and dominance. These findings reflect the restoration of the forest and soil fauna communities and return to the conditions before the fire. However, comparison of the faunal population at trophic levels showed that detritivores in the burned forests experienced the most reduction among all groups and damaged the most from the fire.

Canopy gaps are amongst the most important small-scale phenomena in many temperate, old growth forests, and play a fundamental role in composition and structure of stands. Their occurrence in Hyrcanian forests is associated with numerous effects, including the establishment of species regeneration and increasing forest biodiversity. Due to the importance of in-depth information on canopy gaps, a number of their characteristics were studied in an intact mixed broad-leaved stand in Shast-Kalateh experimental forest Golestan province. We investigated 82 canopy gaps (with a size larger than 40m2) in the compartments 3, 4, 5 and 7 of the forest. For each canopy gap, two parameters of length (L, as the longest distance within the gap) and the width (W, as the largest distance perpendicular to the length) were measured. In addition, data on natural regeneration was sampled within all gaps by species-specific measurement of individuals with DBH 2, with average and median gap size of 470 and 278.6 m2, respectively. The most frequent canopy gaps were those < 400 m2 (71.95%). We observed only few gaps >1000 m2. Most gaps were formed by tree mortality, where hornbeam trees were responsible for 51.45% of gaps. In this study, the increase of gap size to 400 m2 led to increasing the regeneration of tree species. In contrast, the regeneration of main species decreased when gap area increased by more than 500 m2. Hornbeams were the most frequent regenerations in canopy gaps. Finally, the results showed that canopy gaps are crucial factors for regeneration and restoration of forest trees. Therefore, this study calls for increased attention to the different aspects of canopy gaps in order to achieve sustainable management objectives in forestry plans.

Ground skidding damages the marginal trees of the skid trails and may decrease their growth increment at long period. In this research the effects of ground skidding on decay development and extent of the beech trees (Fagus orientalis Lipsky) adjacent to the skid trails, at four age classes, including: 0-5, 5-10, 10-15 and 15-20 year were investigated. After classifying the skid trails to three traffic levels, including: low, moderate and sever, depending on their distance to depot location and trails intersections, the time required for wave transit across the marginal trees at three directions, consisting of: wound direction, wound cross and stem longitudinal direction, was measured, using a stress wave velocity apparatus. After data correction by the apparatus correction coefficient, the tree’s stress wave velocity at the three directions were calculated then statistically analyzed. The results showed that more than 75% of the trees located at 1.5 m. distance adjacent to the skid trails, were wounded by the skidders which resulted in 25% decay. There was also not any decay in the unwounded trees adjacent to the skid trails. Therefore the decay extended when the age of the skid trails increased. Most of the decays were found at trees located at the skid’s trails curves and t down slopes. The results of this research demonstrate an irretrievable, but preventable damage to the standing trees within the skid’s activity extent.