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

Traditionally constructed wetlands face significant limitations in treating tailwater from wastewater treatment plants, especially those associated with sugar mills. However, the advent of novel modified surface flow constructed wetlands offer a promising solution. This study aimed to assess the microbial community composition and compare the efficiencies of contaminant removal across different treatment wetlands: CW1 (Brick rubble, lignite, and Lemna minor L.), CW2 (Brick rubble and lignite), and CW3 (Lemna minor L.). The study also examined the impact of substrate and vegetation on the wetland systems. For a hydraulic retention time of 7 days, CW1 successfully removed more pollutants than CW2 and CW3. CW1 demonstrated removal rates of 72.19% for biochemical oxygen demand (BOD), 74.82% for chemical oxygen demand (COD), 79.62% for NH4+-N, 77.84% for NO3−-N, 87.73% for ortho phosphorous (OP), 78% for total dissolved solids (TDS), 74.1% for total nitrogen (TN), 81.07% for total phosphorous (TP), and 72.90% for total suspended solids (TSS). Furthermore, high-throughput sequencing analysis of the 16S rRNA gene revealed that CW1 exhibited elevated Chao1, Shannon, and Simpson indices, with values of 1324.46, 8.8172, and 0.9941, respectively. The most common bacterial species in the wetland system were Proteobacteria, Spirochaetota, Bacteroidota, Desulfobacterota, and Chloroflexi. The denitrifying bacterial class Rhodobacteriaceae also had the highest content ratio within the wetland system. These results confirm that CW1 significantly improves the performance of water filtration. Therefore, this research provides valuable insights for wastewater treatment facilities aiming to incorporate surface flow-constructed wetland tailwater enhancement initiatives.

IntroductionSoil, as habitat substrate, helps to regulate important ecosystem processes, including nutrient absorption, organic matter decomposition. Water availability and the well-being of humanity are directly linked to soil functions. On the other hand, vegetation with different species and ages have significant effects on the status of the surface soil layer through the creation of diverse environmental conditions and the production of different organic substances. However, few studies have been conducted in relation to the effect of the age of afforestation and the type of vegetation on the soil status. Considering that a practical, complete and effective assessment of soil condition should be the result of simultaneous measurement of physical, chemical and biological indicators, hereupon, the present study aimed to investigate the effect of 20-year old poplar stand, 20-year old maple stand, 10-year old poplar stand, 10-year old maple stand and rangeland cover, in plot 3 of Delak-Khil series of wood and paper forests in Mazandaran province, on the organic layer properties and physical, chemical and biological (including microbial activities, enzyme activity, earthworm population and biomass, the number of soil nematodes and root biomass) properties of the surface soil layer. Materials and MethodsFor this purpose, some parts of the study area were selected which are continuous with each other and have minimum height difference from the sea level, minimum change in percentage and direction of slope. Then, in order to take samples from the organic and surface layer of the soil, three one-hectare plots with distances of at least 600 meters were selected in each study habitats. From each of the one-hectare plots, 5 leaf litter samples and 5 soil samples (30 cm × 30 cm by 10 cm depth) were taken to the laboratory for analysis . In total, 15 litter samples and 15 soil samples were collected from each of the habitats under study. One part of the soil samples was passed through a 2 mm sieve after air-drying to perform physical and chemical tests, and the second part of the samples was kept at 4 °C for biological tests. One-way analysis of variance tests was used to compare the characteristics of organic layer and soil between the studied habitats. In the following, Duncan's test (P>0.05) was used to compare the average parameters that had significant differences among different habitats.Results and DiscussionThe results of this research showed that afforested stands with different ages and pasture cover had a significant effect on the characteristics of the organic and surface soil layers. The results indicated the improvement of most of the characteristics of the organic and surface soil layer in the afforested stands, especially the 20-year old afforestation compared to the rangeland cover. The organic matter produced in 20-year old afforestation, especially with poplar species, had a higher quality (high nitrogen and carbon content and low carbon-to-nitrogen ratio) compared to organic matter produced in 10-year old afforestation and pasture cover. Most of the physicochemical characteristics of the soil under 20-year old afforestation were in a better condition than the other studied habitats. Also, according to the results of this research, the highest values of biological characteristics such as microbial activity, enzyme activity, and the population of earthworms and nematodes were observed in the subsoil of 20-year old afforestation especially with poplar species. Based on the results obtained from the principal component analysis, the higher values of nitrogen, phosphorus, calcium, magnesium and potassium content of the organic layer led to the improvement of soil fertility characteristics, microbial activities, enzyme activity, earthworm population, the number of soil nematodes and root biomass, respectively, under poplar and maple plantation for 20 years, meanwhile, 10-year old plantation, especially with maple species, and rangeland with the production of organic materials with high carbon content and carbon to nitrogen ratio, resulted in the reduction of organic matter decomposition (greater thickness of organic layer), and consequently the reduction of the mentioned properties of the surface soil layer. ConclusionAccording to the findings of this research, it can be concluded that plantation with poplar species, especially after 20 years, had a higher ability to improve the soil condition compared to maple, which can be considered by managers in future afforestation. Also, with the passage of time, the presence of tree covers (poplar and maple) had a higher priority than rangeland cover in improving the fertility status and suitable edaphological conditions of the soil.

Abstract The Hyrcanian forest in northern Iran is threatened by human use and encroachment and has suffered degradation in some areas. The forest has been declared a World Heritage Site and management in the region is shifting from timber production to conservation. There is considerable interest in developing a greater understanding of these diverse forest communities to inform forest management and multiple use plans to maintain the diversity and resilience of these forests. The Hyrcanian forest is characterized by a complex topography of catenas ranging up mountain slopes. Topographic gradients greatly influence microhabitat conditions which in turn impact tree distribution. To date there has been limited research on the impacts of this diverse topography on the spatial distribution of tree species and tree diameters in Hyrcanian forests. Such information is necessary to better understand the regional traits of tree diameters in these natural mixed temperate forests before forest management occurs. We examined the influence of the area’s catena topography on the spatial pattern of tree species and on species stand structure in terms of tree diameter distribution. To quantify these dynamics, we conducted a complete enumeration inventory of all trees with dbh >12 cm within a 7.947 ha study area that included three C-shaped (concave) and three V-shaped (convex) catenas. Geostatistical variogram analysis and Clark and Evans aggregation index were utilized to study the spatial distribution of tree diameters. Beech, alder, hornbeam, linden and Persian maple exhibited clustered patterns, and sour cherry, ash, and oak exhibited random patterns. Geostatistical analysis clearly revealed the substantial influence of catena topography on the diameter distributions of alder and linden, more subtle influence on the diameter distributions of beech, and a possible influence on Persian maple, providing valuable insight into stand structure over neighborhood-based indices alone. Alder and linden both exhibited strong spatial structure in their diameter distributions (56% and 86%, respectively) where their diameter was strongly correlated with trees within 108 m and 83 m, respectively, sharing more similar diameters to each other than trees beyond that distance. Beech, maple, and hornbeam exhibited very weak if any spatial structure over short distances. These findings can be used to support the alignment of forest management practices in managed Hyrcanian forests with goals of protecting and maintaining biodiversity and sustainable forest ecosystems, and to inform geospatial modeling of species diameter distributions in areas where a complete stem-map is not feasible.

Aggregate Stability Index (ASI) and particulate organic matter (POM) are strongly influenced by land use and management. This work illustrates the effects of plantations on ASI and POM-C and POM-N in northern Iran. Three plantations of P. deltoides (PD), T. distichum (TD), A. subcordata (AS), and a fourth site ‒ adjacent abandoned lands (BL, as control) were selected. Soil samples were taken within 16 quadrats of each plantation and BL from the two depths of 0-15 cm and 15-30 cm during the summer. Soil C was significantly higher under TD (2.10%) than under BL (2.02%) > PD (1.61%) > AS (1.30%). Soil N was found in ranked order of AS (8.99%) > TD (7.82%) > PD (5.30%) > BL (3.68%) (P < 0.019). The significantly higher ASI was found under TD (57.49) in comparison with PD (53.10), BL (51.23), and AS (36.57). The POM-C was as follows: TD (0.209%) > PD (0.141%) > AS (0.139%) > BL (0.075%) (P = 0.020). The highest POM-N was found under TD (0.035), followed by AS (0.0284%), PD (0.0288%), and BL (0.007%). The results indicate the positive effect of afforestation on soil ASI and POM-C and POM-N, especially in the surface layers of soil.

Measurement(s) earthworm communities • Abundance • organic material • Diversity • environmental properties Technology Type(s) digital curation Factor Type(s) location Sample Characteristic - Organism Lumbricina Sample Characteristic - Environment soil Sample Characteristic - Location global Machine-accessible metadata file describing the reported data: https://doi.org/10.6084/m9.figshare.13399118

The present study aimed to assess the effect of canopy combination of beech trees and mixed species (beech-hornbeam-maple, beech-hornbeam, beech-maple and pure beech) on microbial indices and soil nutrient stockscharacteristics in Mazandaran Province, north of Iran. Leaf litter sampling was done by using litter traps and soil samples (30 × 30 × 30 cm) were taken in each of the stands with five replicaties under the canopy of beech trees. Characteristics of litter (organic carbon, total nitrogen, carbon to nitrogen ratio, phosphorus, potassium, calcium and magnesium) were measured. The physical, chemical, biochemical and microbial properties of soil (bulk density, Sand, silt, clay, pH, EC, organic carbon, total nitrogen, carbon to nitrogen ratio, sequestration of organic carbon, total nitrogen, phosphorus, potassium, calcium and magnesium, ammonium, nitrate, microbial respiration, metabolic and microbial quotient) were also investigated. The results showed that beech-hornbeam-maple stand had the highest pH, nitrogen sequestration, phosphorus, potassium, magnesium, microbial biomass of carbon and nitrogen, and microbial respiration. Also, the highest amount of soil carbon, carbon to nitrogen ratio, carbon sequestration, metabolic and microbial quotients were allocated to pur beech stands. In addition, the highest ammonium and nitrate levels were also observed in beech- maple and beech-hornbeam stands. According to the present study, beech-hornbeam- maple stand improved the litter quality, nutrient storageand microbial indicators of the soil, followed by beech-hornbeam, beech- maple and pure beech stands. The practical results of this research indicate the positive effects of tree species diversity on improvement of soil qualitaty and health.

Soil plays an essential role in providing ecosystem services, especially in mountain ecosystems which are often considered as fragile and sensitive systems and commonly consist of a mosaic of forest and rangeland plant communities. The relationship between above-ground plant cover and the properties of soil organic and mineral layers in mountain areas are rarely studied. This research aimed to assess the effect of different land covers (i.e. forest, forest-rangeland ecotone, and rangeland) on soil functional indicators, i.e. fertility and biological activities, in the Hyrcanian region of northern Iran. We hypothesized that (i) the presence of tree cover enhances soil fertility and biological activities and creates hot spots (islands) of soil functional indicators especially in the topsoil, (ii) litter quality and organic matter fractions are the drivers for activities of soil organisms, nutrient cycles and transformation processes in mountain ecosystems. Litter (O-horizon including L, F and H layers) and mineral soil samples (in two separate depths of 0–10 cm and 10–20 cm) were taken using iron frames (30 × 30 cm). In total, 45 litter and 90 soil samples were transferred to the laboratory. Soil characteristic especially in the 0–10 cm depth, litter carbon (C), nitrogen (N) and C/N ratio were significantly affected by different land covers showing the maximum of soil organic C and microbial activity under forest. Our findings showed that the studied land covers, as well as litter and soil properties can be separated by PCA output. The first and second axes, accounted more than 50% of the explained variance in each of the studied soil depths. Soils with a better quality of litter (i.e. lower C/N ratio), higher values for organic matter fractions, soil fertility indicators and soil biological activities can be attributed to the forest. In contrast, positions of low soil fertility indicator values and biota abundance were imposed by forest-rangeland ecotone and rangeland. Although each land cover plays a prominent ecological role and takes its place in the evolutionary process, forests are essential because of their capacity to store and transform carbon and nutrients and to create hotspots identified by functional soil indicators. Based on our findings, soil functions decreased ranked in the order forest > forest-rangeland ecotone > rangeland, which can be assigned to the lower density of trees, and the amount of litter mass and litter quality. It can be concluded that tree covers have a prominent role in increasing soil functions, which should be given special consideration in the restoration of degraded mountain ecosystems.

Humus systems are the largest part of organic carbon stock and play an important role in forest ecological processes. Elevation by influencing on the biological and non-biological properties of the forest ecosystem is an important factor for assessing the changes in the trees and distribution of humus systems. In this study, the morphological and chemical characteristics of humus forms in three altitudinal levels (500, 1000, and 1500 m.a.s.l.) and three transects which were 1000 meters apart were investigated. In each transect, 3 plots with 400 m2 area were sampled, and in each plot 5 profiles of humus (in total of 135 profiles) were examined in the central Hyrcanian forest. Humus and samples were taken and transferred to the laboratory for chemical analysis. The results showed that the presence of Iron wood (Scientific name??) and ash (Scientific name??) trees mull humus forms and soil nitrogen stock decreased by elevation increasing. Hornbeam (Scientific name??) and maple (Scientific name??) trees, organic layers' nitrogen, mesomull and leptoamphi humus forms demonstrated strong correlation with the 1000 m elevation. The number of beech trees, carbon in soil and organic layers, organic layers' thickness and humus Amphi forms showed a strong relationship with each other as well as with elevation increasing. The effect of elevation on the composition of the trees coverage is accompanied by the variability in morphology and chemical characteristics of humus forms, so that by identifying tree species in every altitude, we can recognize the quantitative and qualitative properties of humus and soil.

The present study aimed to assess four forest stands, Fagus orientalis Lipsky-Carpinus betulus L.-Acer velutinum Boiss. (FO-CB-AV), Fagus orientalis Lipsky-Carpinus betulus L. (FO-CB), Fagus orientalis Lipsky-Acer velutinum Boiss. (FO-AV), and Pure Fagus orientalis Lipsky (FO) on basis of some soil quality indices in Mazandaran Province, northern Iran. Five samples per stand were taken (0-30 cm), the physical, chemical, and biological characteristics of soil were determined. Nine criteria were selected according to Principal Component Analysis as Minimum Data Set. According to the results, the highest value of litter Ca, density and biomass of earthworm, and C microbial biomass were found in FO-CB-AV. After applying the analytical hierarchy process, the calculated overall priority based on nine criteria showed that the FO-CB-AV stand had a higher ecological potential compared to the other stands. Therefore, the FO-CB-AV stand had more of appropriate conditions for improving soil quality in degraded forest regions compared to the other stands under current conditions.

Draught stress is the most important abiotic stress significantly affecting plants’ growth, development, and performance. This study was carried out to determine the effect of perlite, as a modifying element of soil, on growth and physiological responses of Queues castanifolia seedlings under water deficit stress. A factorial experiment was conducted as randomized complete block design under greenhouse condition of the Agricultural and Natural Resources Research Center in Gorgan, 2015. Perlite treatments at 4 levels (0, 15, , and 35% (V/V)) were added in soil and water stress at 3 levels (40, 70, and 100% irrigation at field capacity) were applied in the pot experiment for 5 months. Some parameters including gas exchange (photosynthesis, stomatal conduction, and transpiration), leaf water potential of seedlings, diameter and height growth, and dry weight of root, stem, leaf, and seedlings were measured in different treatments at the end of the experiment period. Results showed that all parameters were affected by different levels of irrigation and perlite. Water deficit by 40% FC reduced 51% and 68% of photosynthesis and stomatal conductance, respectively. The highest diameter and height growth and dry weight of the seedlings were observed in 25% and 35% (V/V) perlite application under normal and stress conditions, respectively. The use of perlite alleviated the negative effects of water deficit and ameliorated seedling growth. The findings suggest that perlite application in soil is suitable for the production of desirable seedlings under water deficit condition.

Mining activity could affect forest ecosystem health by impact on soil quality. Therefore, the purpose of this study was to investigate effects of mining activities on soil properties in series No. 2, Lavij forest. After field visiting and determining the location of the mine, a square area (4 ha) was laid out with a systematic random sampling (60 × 60 m grid) and 16 plots (20 × 20 m) were systematic randomly considered. Then, an area adjacent to the mine, which was not affected by mining activities, was selected and considered as the control area and plots were also considered as the mentioned method. To study the physical and chemical properties of soil in the two areas, a sample was taken from the upper soil layer (0-10 cm) in each plot. In the laboratory, bulk density, moisture, texture, pH, EC, concentrations of nitrogen, phosphorus, potassium, percentage of organic carbon, lead and cadmium concentrations of soil samples were measured. Results showed that mining caused significant decrease in moisture content, soil pH, and EC, nitrogen and potassium concentrations. The concentration of Pb and Cd in the mining area was significantly higher than the control. According to the results of this study, based on the negative effects of mining activities, it is necessary to consider reclamation of contaminated soil in these areas in the agenda of related Organization.

Earthworms are considered as the most important characteristics in assessing the quality and soil health of forest ecosystems. Earthworms were identified according to their shape and appearance, and their biomass was measured at the laboratory. In order to study the earthworm's biodiversity, Simpson diversity and Margalef richness indices and Camargo evenness were employed. A total of 5 different types of earthworms were identified in the studied habitats. According to the results, all of the earthworms identified were belonged to a family (Lumbricidae), four genera (Lumbricus, Dendrobaena, Aporrectodea and Octolasion) and three ecological groups (Epigeic, Anecic and Endogeic). The Dredrobaena octaedra earthworms from the Epigeic ecological group in all studied habitats were observed in this study and have the highest frequency. The earthworm species belonging to the Anecic and Endogeic ecological groups were not found in the oak, cypresses and degraded areas. In general, ecological groups of earthworms under less degraded natural forest and alder habitats were the most frequent and they had positively significant relation with litter and soil nitrogen and also soil pH, whereas they were negatively related to litter and soil carbon and carbon to nitrogen ratio. As a conclusion, the degradation of forest habitats has reduced the frequency and diversity of earthworms, while the reforestation of degraded forests, especially alder plantation, has increased diversity and abundance of earthworms.

The activity of terrestrial organisms and their populations is an appropriate index for assessing the quality and health of the soil in forest ecosystems, which related to the fertility, and reproduction of the habitat. Current research studied the effect of four forest stands with different composition of Fagus/Carpinus/ Alnus/Diospyros (600 -700 m), Fagus/Carpinus/Alnus (1100 - 1200 m), Fagus/Carpinus (1600 -1700 m) and pure Fagus (2100 - 2200 m) located in Golband district of Noushahr, on litter and soil qualitative characters. In each of forest stands, eight organic and mineral samples (25×25 area to 30 cm soil depth) were taken and transferred to the laboratory. To investigate the difference and or non-difference the studied characteristics among different forest stands, one-way ANOVA and the Duncan multiple tests were employed. The litter (carbon and nitrogen contents) and soil (water content, pH, organic C, total N, earthworm density/biomass, nematode density and microbial activities) properties were measured. According to results, the maximum of soil earthworms (with higher ratio of epigeic) and nematodes recorded under Fagus mixed with Carpinus, Alnus and Diospyros. In addition, tree diversity in mixed stand of Fagus/Carpinus/Alnus/Diospyros improved microbial activities (i.e. basal respiration, substrate induced respiration, microbial biomass C and N, microbial and metabolic quotients and carbon availability index) compared to the other studied forest stands. PCA is indicating the outstanding effects of soil organic and mineral layers on the variation of soil biological properties. The result of this research shows the positive role of tree species diversity in improving qualitative and soil health.

Canopy gaps play an important role in the dynamics of temperate forests. The present study aimed to evaluate the effect of canopy gaps area on soil biochemical activities in Khanikan region of Nowshahr. In this study, 32 canopy gaps with small (195-205 m2), medium (397-406 m2), large (593-604 m2) and very large (792-807 m2) areas, 8 replications for each, were considered. Five points were selected within each canopy gap; soil samples were taken and mixed due to transferring to laboratory for analysis of physico-chemical, biological and biochemical properties. According to findings, whole of soil physico-chemical (except for silt content) and biological properties were significantly affected by different canopy gaps areas. The highest urease activity was found under medium and small (22.97 and 22.54 µg NH4+–N g−1 2 h−1) canopy gap areas, respectively. Medium gaps showed the most values of acid phosphatase (633.75 µg PNP g−1 h−1), arylsulfatase (153.38 µg PNP g−1 h−1) and invertase (273.25 µg Glucose g−1 3 h−1). Greater amounts of dissolved organic carbon (94.73 mg/kg) and dissolved organic nitrogen (34.66 mg/kg) were found under very large and medium canopy gap areas, respectively. Creation of very large canopy gaps was due to increasing of fulvic (454.62 mg/100g) and humic (888.88 mg/100g) acids in the studied forest ecosystem. As a general conclusion, based on forest sustainable management, it is proposed to avoiding of large and very large canopy gaps creation.

After 20 years, the effects of five plantations of Acer velutinum Boiss., Cryptomaria japonica D. Don., Cupressus sempervirens L. var. horizontalis (Mill.) Gord., Pinus taeda L.and mixed stand on soil fertility and quality of the stands were investigated and compared with natural forest to determine the appropriate species for planting in low land of Hyrcanian forests. Five 400 m2 plots were selected randomly- systematic in each stand. Quantitative and qualitative characteristics were recorded. Also, within each plot soil in 0-15, 15-30 and 30-45 cm depths were sampled. The results showed significant effect of reforestation on pH, EC, bulk density, organic carbon, total nitrogen, phosphorus and carbon sequestration in the soil. According to the result, P. taedahas the highest pH (4/6) while A. velutinum has the lowest pH (5.5), natural forest stand has the highest (18/0 ds/m) whereas C. japonica has the lowest (06/0 ds/m) EC. Pinus taeda has the highest organic carbon content (1.29%) and total nitrogen (0.36%) but the natural forest has the lowest amount of organic carbon (1.03%) and total nitrogen (0.08%). The mixed stand has the highest phosphorus (1.9 g/kg) and C. japonica has the lowest one (1.8 g/kg). The A. velutinum has the greatest (292830 Mg/ha) while the natural forest has the lowest (223920 Mg/ha) amount of carbon sequestration. The results showed the conifer stands have been more successful in terms of tree quality characteristic while broadleaf stands were more successful in the quantitative characteristic. Finally, it can be claimed that broadleaves stands were more successful in compare with conifer stands.

Different plant covers have various effects on ecosystem litter and soil characters. This research aims to study the effect of different forest covers (Alnus subcordata C. A. Mey., Quercus castaneifolia C. A. Mey. and Cupressus sempervirens L. var. horizontalis (Mill.) Gord.) on litter, soil and CO2 emission characters in the forest management plan of Nowshahr Neirang-Khanikan. Soil samples were taken from the organic (litter) and mineral (0-15cm) layers using randomly systematic method. Litter quality characters (carbon and nitrogen), soil bulk density, texture, water content, pH, organic carbon, total nitrogen and CO2 emission (in different water content and temperature regimes) were measured in the laboratory. Results showed that the highest values of litter nitrogen, silt, pH were found in alder plantation, whereas greater amounts of C/N of litter, water content, organic carbon, C/N of soil and CO2 emission were found under cypress stand. The highest amount of sand was detected under oak stand. The maximum of CO2 emission were occurred in field capacity moisture regime and higher temperature in whole of studied plantations. The results of this research indicate that afforestation with needle-leaved species, Cupressus sempervirens var. horizontalis, can be effective on the increasing CO2 emission from soil that must be considered in ecosystem management from the global warming point of view.

In forest ecosystems, canopy gaps play an essential role in soil nutrient cycling. In this study, the relationship among different areas of canopy gaps (200, 400, 600 and > 600 m2), biological (e.g., earthworm biomass, microbial respiration, N mineralization, C microbial biomass, N microbial biomass and particulate organic matter of C and N) and also physico-chemical (e.g., bulk density, texture, moisture, pH, organic C, total N and available P, K and Ca) properties, from the top 15 cm of soil, was studied in Beech forests of Sardabrood located in Kelarabad. Three points were considered in center of each canopy gap and also closed canopy, soil samples were taken and mixed due to transferring to laboratory for analysis. According to findings, whole of soil physico-chemical properties (except for silt content and available Ca) were significantly affected by different canopy gaps areas. Also, the highest earthworm's assemblage was under closed canopy and the population was decreased with increasing of canopy gap areas. The characters of microbial respiration, N mineralization and particulate organic of C and N showed ascending trend with increasing of canopy gap areas. Carbon microbial biomass was significantly higher under closed canopy than in different canopy gap areas, whereas the highest amount of N microbial biomass was found within 400 m2 gap areas. According to our data, the highest values of soil chemical and biological properties were related to 400 m2 gap areas. In larger canopy gap areas, soil nutrient elements are decreased due to high decomposition and leaching.

The present study examined the effect of land covers on some of soil quality properties. For this purpose three plantation stands (i.e., Alnus subcordata L., Poplus deltoids L. and Taxadium distichum L. Rich) and an uncultivated land (control area) were considered. Soil samples were collected at two different depths (0-15 and 15-30 cm) and characterized with respect to water content, pH, texture, total organic carbon and nutrient stocks (N, P, K, Ca and Mg). Our findings showed that the highest values of sand, clay and total organic carbon were detected in Alnus subcordata L., Poplus deltoids L. and Taxadium distichum L. Rich, respectively. Whereas the highest of pH, water content and silt were observed in the control area. Measurements of soil nutrient stocks showed that fertility decreased in relation to increased soil depth, with significant differences depending on soil depth. As a conclusion, the broad-leaved species were more successful about most of nutrient stocks than needle-leaved stand and control area.

In temperate forests, formation of canopy gaps by windthrow is a characteristic natural disturbance event. Little work has been done on the effects of canopy gaps on soil properties and fauna, especially earthworms as ecosystem engineers. We conducted a study to examine the reaction of earthworms (density/biomass) and different soil properties (i.e., soil moisture, pH, organic matter, total N, and available Ca) to different canopy gap areas in 25-ha areas of Liresar district beech forest located in a temperate forest of Mazandaran province in the north of Iran. Soil samples were taken at 0-15, 15-30 and 30-45 cm depths from gap center, gap edge and closed canopy using core soil sampler with 81 cm2 cross section. The earthworms were collected simultaneously with the soil sampling by hand sorting method. Our study supports that the canopy gap will create a mosaic of environmental conditions. Earthworm's density and biomass tended to be higher in small canopy gaps compared with the other canopy gap areas. Earthworm's population showed decreasing trend from closed canopy to disturbed sites (gap edge and gap center). The top soil was more appropriate to presence of earthworms although ecological groups have occupied different soil layers. As a conclusion, earthworms can be introduced as good bio-indicator of environmental changes that occur by disturbance.

Traditionally constructed wetlands face significant limitations in treating tailwater from wastewater treatment plants, especially those associated with sugar mills. However, the advent of novel modified surface flow constructed wetlands offer a promising solution. This study aimed to assess the microbial community composition and compare the efficiencies of contaminant removal across different treatment wetlands: CW1 (Brick rubble, lignite, and Lemna minor L.), CW2 (Brick rubble and lignite), and CW3 (Lemna minor L.). The study also examined the impact of substrate and vegetation on the wetland systems. For a hydraulic retention time of 7 days, CW1 successfully removed more pollutants than CW2 and CW3. CW1 demonstrated removal rates of 72.19% for biochemical oxygen demand (BOD), 74.82% for chemical oxygen demand (COD), 79.62% for NH4 +-N, 77.84% for NO3--N, 87.73% for ortho phosphorous (OP), 78% for total dissolved solids (TDS), 74.1% for total nitrogen (TN), 81.07% for total phosphorous (TP), and 72.90% for total suspended solids (TSS). Furthermore, high-throughput sequencing analysis of the 16S rRNA gene revealed that CW1 exhibited elevated Chao1, Shannon, and Simpson indices, with values of 1324.46, 8.8172, and 0.9941, respectively. The most common bacterial species in the wetland system were Proteobacteria, Spirochaetota, Bacteroidota, Desulfobacterota, and Chloroflexi. The denitrifying bacterial class Rhodobacteriaceae also had the highest content ratio within the wetland system. These results confirm that CW1 significantly improves the performance of water filtration. Therefore, this research provides valuable insights for wastewater treatment facilities aiming to incorporate surface flow-constructed wetland tailwater enhancement initiatives. [ABSTRACT FROM AUTHOR]