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Reforestation has long been the best practice to restore degraded forests due to human interventions. In this paper we investigated the effect of forest degradation (DNF) along with reforestation using 4 endemic species (Alnus subcordata, ASP; Acer velutinum, AVP; Cupressus sempervirens, CSP; Quercus castaneifolia Mey, QCP) on forest’s soil chemical and biological indicators compared to a close-to-virgin natural forest (VNF). For this study, a total of 24 physico-chemical and 25 biological and microbial indicators were measured in soils of all 6 forest stands along with the litter properties. Results showed that the lowest soil quality was observed under DNF, CSP, and QCP which was the result of forest cover degradation in DNF and low litter quality, especially low pH and high C:N, in CSP and QCP. Soil fauna communities were significantly affected by tree species. We found two times higher density of earthworms in VNF compared to ASP, but in DNF the density was 5 times lower than VNF. We found no epigeic earthworms in QCP, CSP and DNF and no endogeic earthworms in DNF. Acarina and Collembola density was high in VNF and ASP, but they showed significant differences (VNF>ASP), and their density sharply decreased in other stands, especially in CSP (3 times lower than VNF) and DNF (8 to 10 times lower than VNF). Nematode density was statistically equal in VNF, ASP, and AVP, but significantly lower in other stands. Protozoa, bacteria and fungi densities were significantly higher in VNF and ASP (VNF>ASP) compared to each other and other forest stands. Basal respiration, substrate induced respiration, microbial biomass N and P, and carbon availability index was also higher in VNF and ASP compared to other stands. Although VNF has the best condition because of old forest cover and high diversity, ASP soil showed significant improvements, demonstrating the importance of litter quality in soil restoration. Restoration effectiveness ranking of the four tested species on soil improvement are therefore ASP>AVP>QCP>CSP. The significant improvement of soil quality under ASP compared to other reforestated stands, only after 3 decades, emphasizes the importance of tree species selection and litter quality on soil chemical and biological restoration.

The rehabilitation of heavy metal-contaminated lands is a challenging issue worldwide. The application of effective eco-friendly techniques and materials is necessary for amending the contaminated soils, and the in-situ results should be examined. The present study investigated the effect of zero-valent iron-nanoparticles (Fe0-NPs) and cellulosic wastes (CW) on the lead (Pb) and cadmium (Cd) uptake and nutrients’ (N, P, K) concentration of maple seedlings in contaminated soil. First, one-year-old seedlings were planted in pots containing unpolluted soil (volume = 3 Kg), and then the soil was contaminated by adding Pb (0, Pb100, Pb200, and Pb300 mg kg-1) and Cd (0, Cd10, Cd20, and Cd30 mg kg-1) solutions. The CW (0, 10, 20, 30 g/100g soil) and Fe0-NPs (0, 1, 2, 3 mg kg-1) treatments were applied to the soil before and after Pb and Cd addition, respectively. The biomass of seedlings and the concentration of nitrogen, potassium, and phosphorus in leaves were measured. Leaves, stems, and roots were digested to measure the Pb and Cd concentrations. Results showed that CW and Fe0-NPs improved N, P, and K concentrations in leaves at all levels of contamination. The lowest concentration of Pb and Cd in all organs and treatments was observed in the highest level of Fe0-NPs. The cellulosic waste and Fe0-NPs (the highest level only) significantly increased the soil pH at all levels of contamination. Our findings suggested that the use of Fe0-NPs (3 mg kg-1) and CW (30g/100g soil) could be appropriate for reducing the bioavailability of Pb and Cd in contaminated soil and improving the growth of maple seedlings.

Introduction Forests, encompassing approximately 30% of the Earth's land area, hold significant ecological importance due to their rich biodiversity and the multitude of environmental services they provide. These ecosystems outperform other terrestrial habitats, making them invaluable to all life forms on our planet. The destruction of forest habitats and changes in land use patterns exert significant impacts on the variability of soil quality indicators. The consequence of forest degradation encompass various adverse consequences, including the destruction of wildlife habitats, climate change, global warming, diminishing plant and animal biodiversity, and reduced water conservation capacity. Extensive research has been conducted to investigate soil quality in diverse land uses within temperate regions. However, there is a noticeable scarcity of studies focusing on semi-arid regions. It is imperative to note that a comprehensive and practical assessment of soil condition necessitates the simultaneous measurement of physical, chemical, and biological indicators. Such an integrated approach ensures a thorough and effective evaluation of soil quality. The primary objective of this study was to assess the impact of various land uses, namely natural forest (C. betulus - P. persica), plantation (Q. castaneifolia), garden, rangeland, and agricultural lands (rice), on the physical, chemical, and biological properties of the organic and mineral soil layers. Specifically, the investigation focused on the evaluation of fauna and flora, microbial communities, and enzyme activities. The study was conducted in the semi-arid region of Kajur Nowshahrmourd. Materials and Methods To achieve this objective, contiguous sections of the study area were carefully chosen, ensuring minimal variations in height above sea level, percentage and direction of slope. Subsequently, three slice of one-hectare dimension plots (100 × 100) were selected within each study habitat, with a minimum distance of 600 meters between them. From each one-hectare plot, four leaf litter samples and four soil samples (30 cm × 30 cm, 10 cm depth) were collected and transported to the laboratory for analysis. In total, 12 litter samples and 12 soil samples were collected from each of the habitats. The soil samples were divided into two parts: one part was air-dried and then passed through a 2 mm sieve for subsequent physical and chemical testing, while the other part was stored at 4 degrees Celsius for biological assessments. One-way analysis of variance tests were employed to compare the characteristics of the organic layer and soil among the studied habitats. Furthermore, Duncan's test (P>0.05) was utilized to compare the average parameters that exhibited significant differences among the different habitats. Results and Discussion The findings derived from this investigation underscore the substantial variability in organic layer characteristics across different vegetation types. Natural forests emerged as the most prominent in terms of thickness, nitrogen content, and calcium concentration, whereas agricultural areas exhibited the lowest values. Grassland areas displayed the highest carbon content and carbon-to-nitrogen ratio, while agricultural and natural forest areas demonstrated comparatively lower values. Agricultural lands demonstrated elevated bulk density and sand content, whereas natural forests exhibited the lowest values. Notably, natural forests showcased the highest porosity, aggregate stability, silt percentage, and macro- and micro-aggregate quantities, while agricultural areas presented the lowest values. Chemical analysis of the soil indicated that natural forests recorded the highest values for most chemical characteristics, while agricultural lands displayed the lowest values. Biological attributes generally exhibited the highest levels in natural forests and the lowest levels in agricultural areas. Specifically, the abundance and biomass of epigeic and endogeic fauna did not exhibit significant differences among different land uses during the summer season. Managed forests demonstrated the highest values for moisture content, basal respiration, substrate-induced respiration, and microbial biomass carbon. Conversely, agriculture exhibited the lowest values in these regards. The microbial biomass carbon-to-nitrogen ratio was highest in agricultural areas, while natural forests displayed the lowest value. Natural forests displayed the highest values for most nitrogen transformation characteristics, whereas agricultural areas exhibited the lowest values. Nitrogen nitrification and mineralization showed a decreasing trend across different land uses during the summer and autumn seasons. The type of vegetation cover also significantly influenced the variability of soil ammonium and nitrate levels. Conclusion Based on the results obtained from this study, it can be inferred that the preservation and conservation of natural forest cover should be given utmost importance. Additionally, in degraded areas, the establishment of woody vegetation can serve as a viable approach for the restoration of ecosystems with similar ecological conditions. Furthermore, the presence of tree covers, specifically C. betulus and P. persica, is of greater significance compared to rangeland and agricultural land uses in enhancing soil fertility and creating favorable biological conditions. As a result, this research provides valuable insights into the impact of different land uses on the characteristics of the organic and mineral soil layers in mountainous habitats. The information obtained can be instrumental in guiding natural resource managers and offering practical assistance in decision-making processes. [ABSTRACT FROM AUTHOR]

Introduction Soil, 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 Methods For 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 X 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 Discussion The 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. Conclusion According 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 FROM AUTHOR]

The present study aimed to examine the impacts of small (85.12 m²), medium (325.21 m²), large (512.11 m²) and very large (723.85 m²) gaps on soil properties in a mixed beech -- hornbeam stand of northern Iran. As well as the value of pH, organic matter and carbon, total nitrogen, cation exchange capacity (CEC), phosphorus, potassium, calcium, nitrogen mineralization, microbial respiration, earthworms density and biomass of soil samples (0 - 15, 15 - 30 and 30 - 45 cm depths from gap center, edge and closed canopy positions) were measured in laboratory. Significantly effects of gaps size were found on soil properties as the highest values of CEC, density and biomass of earthworms observed in small gaps. The highest values of carbon to nitrogen ratio, phosphorus, potassium and calcium were detected in medium gaps. The most amounts of organic matter and carbon, nitrogen mineralization devoted in very big gaps. Greater amounts of pH, total nitrogen and microbial respiration were detected in big and very big gaps. It was found that gap position had a profound effect on soil characters as the highest values of pH, organic matter and carbon, total nitrogen, phosphorus, potassium, calcium, nitrogen mineralization, microbial respiration observed in gap center. The greatest amounts of carbon to nitrogen ratio, CEC, density and biomass of earthworms were detected in closed canopy. According to the results, soil upper layers showed the highest values organic matter and carbon, soil nutrition elements and biochemical activities, whereas the highest amounts pH, carbon to nitrogen ratio, CEC and density and biomass of earthworms were observed in deeper soil. It is concluded that opening areas of canopy cover should be less than 400 m² in beech forests of northern Iran with considering of soil properties. [ABSTRACT FROM AUTHOR]

Vegetation degradation in natural environments leads to considerable fluctuations in soil function indicators, particularly in the sensitive and delicate habitats of semi-arid regions. In this study, the dynamic of both litter and soil properties was examined in northern Iran, in sites with Crataegus melanocarpa and Berberis integerrima dominance. The chosen sites have been degraded in 1993 due to exploitation for fuel production. Litter and soil (0-10, 10-20 and 20-30 cm depths) samples were collected in sites that have been degraded [i.e., 10-years post-degradation (2003), 20-years post-degradation (2013), and 30-years post-degradation (2023)]. A site not to exposed to degradation (year 2023) was also included as a control. In total, 48 litter samples (4 study sites × 12 samples) and 144 soil samples (4 study sites × 3 depths × 12 samples) were collected. Our findings showed a significant reduction of approximately 60-70% in the chemical characteristics of the litter, such as phosphorus (P) and magnesium (Mg) after 10-years post-degradation (2003) compared to the control site. Soil fertility indicators were also reduced 2-6 times as a result of habitat degradation. Aligned with this, the biota population in the 10-year post-degradation site showed a decrease of 70-90% with respect to the control. Moreover, the densities of fungi and bacteria decreased by approximately 30%-70% and 45-80% respectively compared to the 30-year post-degraded site. The peak activation of soil enzymes including urease, acid phosphatase, arylsulfatase, and invertase was found in the site that was not subjected to degradation, being 3.5, 5.8, 6.7 and 6.7- times higher in comparison to the 10-year post-degradation site. Overall, the results showed that in the non-degraded ecosystems, the input of plant-based organic matter was accompanied by an increase in soil fertility, organism population and soil function. This pinpoints the importance of protecting plant species in these areas, while in degraded areas planting native species adapted to the region's climate and fertilization could significantly contribute to restoring these areas., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Landfills pose a global issue for soil functionality and health, especially in underdeveloped nations where limited resources impede the adoption of comprehensive waste management policies, such as waste processing and sorting techniques. Leachate emissions from waste landfills are a cause for concern, primarily due to their toxic effect if left uncontrolled in the environment, and the potential for waste storage sites to produce leachate for hundreds of years after closure. Few efforts have been made to improve waste collection and disposal facilities in the world, especially in developing countries. This research aims to investigate the influence of waste leachate on soil health indicators in natural woodland and rangeland ecological systems in a semi-arid mountainous region in the north of Iran. Based on results, forest unpolluted sites (2008) exhibited the highest values of nutrient elements in litter and root components. Landfills led to a rise in soil bulk density and a simultaneous decrease in soil organic matter (SOM), porosity, aggregate stability, particulate organic carbon and nitrogen (POC and PON), as well as available nutrients, ammonium (NH 4 + ) and nitrate (NO 3 - ) levels. Additionally, microbial parameters (respiration and biomass) and enzymes (urease, acid phosphatase, arylsulfatase and invertase) experienced a decrease in areas affected by the landfill sites over time of 2008-2023. Forest and rangeland landfill sites (2023) sites had lower density and biomass of the three earthworm groups. Acari, Collembola, nematodes, protozoans, fungi and bacteria were also reduced in landfill sites (nearly 1-2 times more in uncontaminated forest and rangeland sites). Lumbricus terrestris earthworms exhibited a clear presence in all the studied sites, and this demonstrates the ability of this earthworm species to be active in severe pollution conditions. The spatial pattern of soil cadmium and lead changes indicates the high variance of these characteristics under the influence of landfills in the study sites. Finally, the soil health indicators (according to soil physical, chemical, and biological parameters) decreased from forest unpolluted sites in 2008 to rangeland landfill sites in 2023, which is linked to the release of landfill leachate. These results are noteworthy for all countries and governments that rely on natural ecosystems for waste management without engineering operations or technical intervention. Furthermore, both governments and stakeholders must implement effective waste management systems. The research offers valuable information that can assist decision-makers engaged in sustainable solid waste management in Iran and comparable areas. Besides that, it is highly recommended to prioritize recycling and phytoremediation processes. Ultimately, worldwide efforts to achieve environmental sustainability need a significant focus on the effective management of hazardous waste. Consequently, investigations covering this topic should be continued, as they allow the evaluation of the environmental effects of the gradual accumulation of pollution in soils surrounding uncontrolled municipal solid waste landfills., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

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 NH 4 + -N, 77.84% for NO 3 - -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., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Ali, Min, Yu, Kooch, Marnn and Ahmed.)

In natural habitats, especially in arid and semi-arid areas that are fragile ecosystems, vegetation degradation is one of the most important factors affecting the variability of soil health. Studying physicochemical and biological parameters that serve as indicators of soil health offers important information on the potential risk of land degradation and the progression of changes in soil performance and health during recovery periods. This study specifically examines the impact of vegetation degradation on soil health indicators and the duration needed to improve the physical, chemical, and biological parameters in a semi-arid mountainous area site types with the dominance of Quercus macranthera Fisch & C.A. Mey and Carpinus orientalis Miller in northern Iran. In different years (2003, 2013, and 2023), litter and soil samples (at depths of 0-10, 10-20, and 20-30 cm) were collected in different types of degraded sites. Additionally, in 2023, a non-degraded site was chosen as a control and similar samples were collected. A total of 48 litter (12 samples for each of the study site types) and 144 soil (4 study site types × 3 depths × 12 samples) samples were collected. In order to investigate the spatial changes of soil basal respiration (or CO 2 emission), which is involved in global warming, from each site type, 50 soil samples were taken along two 250-meter transects. The findings showed that litter P and Mg contents in the non-degraded site were 1.6 times higher than in degraded site types (2003). Following vegetation degradation, soil fertility indicators decreased by 2-4 times. The biota population was lower by about 80 % under the degraded site types (2003) than in the non-degraded site, and the density of fungi and bacteria in the degraded site types was almost half that of the non-degraded site types. Geostatistics showed the high variance (linear model) of CO 2 emissions in areas without degradation. In addition, vegetation degradation significantly reduced soil carbon and nitrogen mineralization. Although soil health indicators under the degraded vegetation have improved over time (30 years), results showed that even thirty years is not enough for the full recovery of a degraded ecosystem, and more time is needed for the degraded area to reach the same conditions as the non-degraded site. Considering the time required for natural restoration in degraded site types, it is necessary to prioritize the conservation of vegetation and improve the ecosystem restoration process with adequate interventions., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

A degraded forest is the outcome of a degradation process that has adverse effects on ecosystem functions and services. This phenomenon results in alterations of soil physicochemical and biological properties, which serve as valuable indicators for assessing soil health that has been recognized as a crucial component of soil quality. For several decades, the conversion of forested areas into rangeland has been documented in specific regions of the world. There is a widespread lack of global understanding regarding the lasting consequences of land degradation on soil health indicators. The present study aims to investigate the impact of forest degradation on soil health indicators in a mountainous semi-arid region located in northern Iran. The study area was predominantly forested, but due to human activities over the past 30 years, it has been transformed into three distinct land uses: forest, forest-rangeland ecotones and rangeland. In each of these land covers, a total of 20 litter (O-horizon) and 20 soil (from two depths of 0-15 and 15-30 cm) samples were collected in the summer (August 2022) season. According to our results, the highest litter thickness, P and Mg were in forest ecosystem, the lowest in rangeland ecosystem. The findings indicated that following the conversion of forest to rangeland, there was a decrease in soil aggregate stability, porosity, soil organic matter, POC, PON, NH 4 + , NO 3 - and nutrient levels, while soil bulk density increased. The forest ecosystem showed notably higher C and N stocks (45 and 5.21 Mg ha -1 ) in comparison to the rangeland (38 and 3.32 Mg ha -1 ) ecosystem. In addition, P, K, Ca, and Mg exhibited elevated levels within the total root of the forest ecosystem (2.12, 1.23, 0.71, and 0.38 %, respectively), whereas the lower values (1.29, 1.01, 0.43, and 0.23 %, respectively) were found in the rangeland ecosystem. Following the shift of land cover from forest to rangeland, soil fauna, microflora populations, soil enzymes and microbial activities decreased (about 1-2 times higher in the forestland). This research emphasizes the urgent need to advance sustainable management practices to prevent further degradation and promote the implementation of restoration or rehabilitation techniques in degraded forests. Despite being conducted in a semi-arid region situated in northern Iran, the findings of this study have considerable value for the sustainable management of soil and land conservation in various other semi-arid regions around the world., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

There are contrasting reports about whether and how vegetation types influence litter and soil properties. Accurate and comprehensive assessment of the complex relationship between vegetation types, litter and soil characteristics in semi-arid mountain landscapes is almost unknown. Thus, the purpose of this research was to study the effects of (1) Carpinus orientalis Miller., (2) Crataegus melanocarpa M.B., (3) Rhamnus pallasii Fisch. and C.A.Mey, (4) Agropyron longiaristatum Boiss, (5) Bromus tomentolus Bioss. and (6) Hordeum vulgare L. on litter properties and soil physical, chemical, biochemical and biological features in northern Iran. A sampling of the organic layer (litter) and mineral soil (30 × 30 cm) from a depth of 0-10 cm was done for all characteristics in the summer season and for soil microclimate and biological characteristics in the summer and fall seasons. A total of 90 litter samples, 90 soil samples in summer and 90 soil samples in fall (6 vegetation types × 2 seasons × 15 samples) were taken from the area and transferred to the laboratory. Results showed that the Carpinus improved litter properties, soil organic matter contents, total N and available nutrients (P, K, Ca and Mg) and enzyme activities (urease, acid phosphatase, arylsulfatase and invertase). In addition, the population of earthworm groups (epigeic, anecic, and endogeic), acarina, collembola, nematodes, protozoa (especially in the fall season) and bacteria and fungi (especially in the summer season) under Carpinus significantly increased. Data analysis demonstrated higher soil fertility and biological activities in the woody vegetation, which can be assigned to the higher litter input and nutrients. Overall, the findings of this study showed that woody vegetation, especially Carpinus, can improve soil properties at high altitudes of mountainous, semi-arid sites that are often considered as especially fragile and sensitive ecosystems., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Soil quality and function in forest environments are influenced by the interaction of soil-forming parameters and silvicultural systems. Hyrcanian forests were recently accepted as a UNESCO World Heritage Site, which extends across an area of approximately 1.8 million hectares and ascend to an elevation of 2800 m above sea level (m.a.s.l). In these woodlands, Oriental Beech (Fagus orientalis Lipsky) is the predominant tree species and could be observed at 700-1500 m.a.s.l., and occur on different parent rocks. Shelterwood and single-tree selection techniques have been the primary management methods for beech forests for the past forty years. Studies investigating the impacts of silvicultural systems have not yet been done on soil and forest floor features on different bedrock geology and altitudes. Therefore, in this study, we examined the influence of single-tree selection and shelterwood methods, 25 years after employing those methods, on soil quality and function compared to control areas (intact forests) in Hyrcanian beech stands. For this purpose, 15 forest floor (30 × 30 cm) and topsoil (0-10 cm depth) samples in each silvicultural systems (i.e., single-tree selection and shelterwood methods and control zones) × 4 regions (including Rasht, Nowshahr, Sari and Gorgan) × 4 altitude levels (with averages of 800, 1000, 1200 and 1400 m.a.s.l.) were considered. According to our findings, the investigated forest regions, forest floor and soil characteristics across various locations spots could be separated by principal component analysis output, and more than 85% of the variance was explained by the first and second axes. The structural equation model showed that the region, altitude and silvicultural systems had an effective role in the changes in soil biological activities by influencing the forest floor, and the soil physicochemical features. Based upon the network model, the C/N ratio, the sand content, the soil aggregate stability, the available K, the fulvic acid, and the Acarina density were found to be prominent factors with regard to soil function. In the control sites, increased soil organic material fractions, microbial/enzyme and biota activities were detected, particularly at the lower altitudes of the Nowshahr site, which had geological formations of dolomite and calcic layers. Taken together, it seems that the single-tree method, commonly referred to as the close-to-nature technique produces more suitable conditions for soil functioning compared to the shelterwood management approach. Silvicultural systems, bedrock geology and altitude can have major detrimental effects on soil function and fertility, over the long-term, impacts may increase with harvest intensity., Competing Interests: Declaration of Competing Interest The authors declare that they have no conflict of interest., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The storage of municipal solid wastes in unengineered landfills poses a severe threat to soil functions and health. Wastes seriously threaten human health and the terrestrial ecosystem, especially due to heavy metals. There is a general knowledge gap about the long-term impacts of storage wastes on the soil health indicators which are effective on soil functions. This investigation focuses on the examination of landfill leachate on soil health indicators from different years in the Hyrcanian forest region in northern Iran. For this purpose, soil sampling was done in the summer of 2012 and 2022 (from three depths of 0-10, 10-20, and 20-30 cm and on a surface of 30 cm × 30 cm). Soil samples were randomly collected from a polluted forest used as waste storage and a nearby unpolluted protected forest. In addition to the general soil physical, chemical and biological parameters, the amounts of cadmium (Cd) and lead (Pb) in the soil were also measured. Simultaneously with soil sampling, earthworms (from a depth of 0-30 cm) were collected and identified. Also, the concentration of Cd and Pb in the earthworm's biomass were measured in the laboratory. We found that unpolluted sites had maximum values of N, K, P, and Ca than the polluted sites. In addition, a decrease of soil aggregates stability, nutrient contents, microbial and enzyme activities, and also fauna and microflora abundance were found in the polluted sites in the period 2012-2022. Soil Cd and Pb contents were more in the polluted site in 2022 compared to the unpolluted site. Lumbricus rubellus and Lumbricus terrestris earthworms had significantly higher population in the polluted sites and higher accumulation of Cd and Pb in biomass. According to our results, soil health decreased in the order unpolluted site 2022 > unpolluted site 2012 > polluted site 2012 > polluted site 2022, which corresponds with the reduction of soil health during the release of landfill leachate. This investigation contributes to understand landfill pollution derived from leachate and its effects on soil physical, chemical and biological parameters to help managing landfill leachate. Therefore, the main issue is choosing a landfill system that minimizes the risk of pollution, installing a leachate collection system and constructing a landfill with engineering principles that can reduce the effects of urban waste pollution on soil health. We emphasize that landfilling is dangerous for the environment, so the government should implement sanitary landfilling to prevent further contamination of surface and underground waters, as well as soil in the precious Hyrcanian forest., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The temporal and spatial dynamics of soil fauna in many terrestrial ecosystems are still not fully understood, while soil fauna is one of the most critical characteristics in assessing soil quality. Therefore, the effects of native [Quercus brantii (QP) and Amygdalus scoparia (AMP)] and non-native [Cupressus arizonica (CUP) and Pinus eldarica (PIN)] plantations and natural trees [Quercus brantii coppice trees (QNC), standard (QNS), and Amygdalus scoparia (AMN)] on diversity and abundance of macro- and mesofauna were done in the semi-arid forest of Zagros, Iran. Samples were collected beneath the canopy of woody species and the outer edge of the canopy in spring and summer seasons. For this purpose, soil samples [(7 samples per woody species + control) × 2 seasons × 3 replicates] were taken from 0 to 20 cm depths. Each soil sample was a mix of three soil cores. For the macrofauna, 15 species belonging to four families (in spring) and 17 species in nine families (in summer) were collected and identified. For the soil mesofauna, 14 species belonging to 14 families (in spring) and 13 species in 13 different families (in summer) were identified, respectively. The fauna diversity indices under the canopy of studied species were higher in summer season than in spring. The result showed that the macrofauna diversity was affected by tree species, while mesofauna was affected by seasonal changes. Macrofauna biodiversity was higher under the canopy of PIN and CUP than other trees. Principle component analysis showed that the diversity of the macrofauna was higher under the canopy of PIN and CUP, and influenced by soil characteristic properties, soil properties did not influence them. Yet the diversity of the mesofauna was affected by soil characteristics and was higher in areas with higher organic carbon, nitrogen, substrate-induced respiration, basal respiration, microbial carbon biomass, and alkaline phosphatase. In addition, mesofauna biodiversity had a significant positive correlation with the soil quality index (SQI). SQI was higher under the canopy of natural stands, especially the QNS. Conservation of native species (QNS, QNC, and AMN) and plantation with native deciduous species (QP and AMP) seem to moderate environmental conditions and increase soil macro- and mesofauna diversity and SQI., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Mountain landscapes are highly heterogeneous due to topography, notably positions along slope and slope shapes, which control ecosystem mechanisms. We hypothesized that tree dieback is controlled by topography, selecting productive and less diverse communities in lower slopes, and stress-resistant and more diverse communities on upper slopes. Understanding how this heterogeneity drives vegetation patterns should provide benchmarks for ecosystem management of mountain forest dominated by Quercus brantii. Woody communities were sampled along convex vs concave topography (i.e., ridge vs talweg), and with measurements of tree dieback severity, environmental variables (litter depth, soil quality, rock outcrop), stand structure (canopy cover, mistletoe infestation, tree diameter and height, diameter and height differentiations, oaks' number from sprout-clumps or seed-origin), and biodiversity. Slope position was the most significant driver that affected all variables, excepted evenness. Dieback severity was higher on slope shoulders and summits, and lower in lower slopes where trees were the most productive: taller, larger, more homogeneous, and mostly seed-origin. Catena shape affected the diversity and dieback severity, both higher in talwegs, but had no effect on environmental variables and little on stand structure. Outputs indicate that the higher diversity of woody plants is on upper slopes supporting stress-resistant community associated with more severe dieback and mistletoe infection probably because frugivore birds attracted by the shrubs' fruits. Semi-arid forest management must consider the shaped-slope ecosystem heterogeneity by preserving ridges that are more susceptible to tree dieback, and naturally support biodiversity. Restoration measures on lower fertile slopes could be carried out by oak planting or seedlings under the cover of shrubs to counter dieback effects and environmental stresses. In addition, forestry measures can be taken in lower positions for the conversion of coppice to high oak forest to potentially consider a moderate forestry., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Soil function refers to all the roles and services that the soil performs, and can be assessed by measuring physical, chemical and biological properties. In any case, studies on the state of fertility and biological activities are now emphasized as indicators of soil functions. Degradation of rangelands and their conversion to agricultural land is one of the most common land use changes in different parts of the world, with significant impacts on soil functions. Not much is known about the effects of land use change (especially rangeland to orchards of different ages) on soil function indicators in semi-arid areas. In the current study, the following five types of land covers were considered in a semi-arid region of northern Iran: (1) enclosured rangeland, (2) 10-year-old apple orchard, (3) 25-year-old apple orchard, (4) 10-year-old walnut orchard, and (5) 25-year-old walnut orchard. Results showed that the apple orchards (25-year-old) had a more fertile soil and a higher biological activity than the other land uses studied. Based on heat plots of soil properties under different land uses, the apple orchards (25-year-old) formed hot spots of soil functional indicators in the study area, followed by the walnut orchard (25-year-old) > enclosured rangeland > apple orchard (10-year-old) > walnut orchard (10-year-old). Although the conversion of natural lands (i.e., rangelands) to anthropogenic ones (i.e., orchards) is generally associated with negative feedbacks, tree species can be used (by creating forested rangeland or a combination of rangeland-agriculture) in areas with low soil function to improve soil conditions (in the long term)., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Soil quality can be assessed by measuring its physical, chemical and biological properties. In terrestrial ecosystems, the knowledge of the status of soil quality under different land use/cover can increase our understanding of processes related to soil functioning and help to properly managing ecosystems and increase their services. Conversion of the forest to rangelands is one of the most common forms of land use change having a significant effect on soil quality indicators. Here, we addressed the following objectives: (ii) to study the current status of soil physical, chemical and biological characteristics after more than thirty years of land use change from forest (dominated by Carpinus betulus and Parrotia persica) to rangeland, and (ii) to provide an overview of the spatial distributions of soil properties in forest and rangeland covers using a geostatistical method. For this, two sites (i.e., forest and rangeland) were selected in northern Iran. Within each site, 50 soil samples were collected at 0-10 cm depth along two sampling lines (250 m length) with a total of 100 soil samples for each site. Results showed that following the change of land use from forest to rangeland soil porosity, aggregate stability, pH, electrical conductivity and nutrient (i.e., total N and available P, K, Ca and Mg) contents increased, whereas soil bulk density and C/N ratio decreased. In addition, the population of soil biota (i.e., earthworms, acarina, collembola, nematode, protozoa, bacteria and fungi), microbial and enzyme activities decreased after more than thirty years of land use change from forest to rangeland. Principal component analysis confirmed that forest site had a more fertile soil and a higher biological activity than rangeland cover. Based on heat plots of soil properties, forest ecosystems created hot spots of soil quality indicators in the study area. Based on the geostatistical approach, most of the soil variables in the rangeland site followed a linear model, while in the forest site, most models were exponential and spherical. The fractal dimension values of the soil properties in the forest (1.62-1.99) had larger variations than in the rangeland (1.75-1.99) site. As a general conclusion, soil quality was not improved after more than thirty years of land use change from forest to rangeland, suggesting that degraded forest habitats should be restored by native tree species rather than converted to other land uses., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Vegetation degradation can have significant effects on organic matter fractions as well as various soil characteristics. All these can lead to the changes in soil microbial communities, which are main drivers of nutrient cycles. This is especially important for mountainous ecosystems that are very sensitive and fragile habitats due to their climatic conditions, but less attention has been paid to them. Thus, Mirkola mountainous region (northern Iran) with semi-arid climate and vegetation being dominated by Crataegus and Berberis shrubs were investigated in this study. Sites with different intensities of vegetation degradation [light (60-70 % coverage), moderate (30-40 % coverage) and heavy (0-10 % coverage)] and also non-degraded control sites (90-100 % coverage) were selected. In order to avoid pseudoreplication, three plots, each with an area of 1 ha (100 m × 100 m), were used for each of the four studied habitats. Soil (in three soil depths at 0-10 cm, 10-20 cm and 20-30 cm) samples were collected from the corners and also the center (n = 5) of the plots using iron frames (30 × 30 cm). A total of 180 soil samples (4 habitats × 15 sample × 3 depths) were transferred to the laboratory. Labile and non-labile contents of soil organic matter (SOM) (C and N in soil particles and aggregates, C and N stocks, particulate and dissolved organic matter, hot-water extractable carbohydrate, C and N mineralization) were measured in each of these sites. Results showed that vegetation degradation might result in both labile and non-labile SOM losses. SOM and its associated properties were highest in the non-degraded sites, whereas, lower values were common under degraded areas. Based on the obtained data, vegetation cover can enhance the amount of organic matter entering the soil (especially in the surface layers) and formation of fertile islands in ecosystems. Accordingly, vegetation protection is emphasized to maintain stability and provide ecosystem services in mountainous semi-arid regions., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Soil biological properties are good indicators for the evaluation of soil quality, introduced as key indicators in soil health, which is in line with the nutrient cycles in terrestrial ecosystems. To the best of the authors' knowledge, responses of belowground biota to habitat degradation have received little attention. The present study aimed to study the effect of different intensities of vegetation degradation [heavy (0-10% coverage), moderate (30-40% coverage) and light (60-70% coverage)] and non-degraded sites (as control; 90-100% coverage) in lands covered by Crataegus and Berberis shrubs on soil fauna, microbiota and microbial activities in the north of Iran. From each of these sites, 45 soil (30 × 30 cm area) samples were taken from 0 to 10 cm, 10-20 cm and 20-30 cm depths and 180 samples were transferred to the laboratory. According to principal component analysis, the studied habitats can be distinguished based on soil health and functional characteristics. In this regard, due to the more fertile soil in ecosystems without degradation, highest soil biological activities belonged to these areas. Following the increase in the intensity of degradation, the population of soil organisms and microbial activities are suppressed due to reduction of organic matter inputs, unsuitable soil microclimate, increase in soil erosion and finally depletion of soil nutrients. The results of this study indicate the dependence of soil quality on aboveground vegetation cover, especially in the topsoil, so the vegetation degradation can cause severe damages to soil health in semi-arid regions., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2022 Elsevier B.V. All rights reserved.)

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., (© 2022. The Author(s).)

Earthworms are an important soil taxon as ecosystem engineers, providing a variety of crucial ecosystem functions and services. Little is known about their diversity and distribution at large spatial scales, despite the availability of considerable amounts of local-scale data. Earthworm diversity data, obtained from the primary literature or provided directly by authors, were collated with information on site locations, including coordinates, habitat cover, and soil properties. Datasets were required, at a minimum, to include abundance or biomass of earthworms at a site. Where possible, site-level species lists were included, as well as the abundance and biomass of individual species and ecological groups. This global dataset contains 10,840 sites, with 184 species, from 60 countries and all continents except Antarctica. The data were obtained from 182 published articles, published between 1973 and 2017, and 17 unpublished datasets. Amalgamating data into a single global database will assist researchers in investigating and answering a wide variety of pressing questions, for example, jointly assessing aboveground and belowground biodiversity distributions and drivers of biodiversity change.

The type of vegetation cover affects the contents of organic matter and other soil features that can lead to variability of soil microbial processes, which play a key role in the nutrient cycle. This issue is especially important in mountainous semi-arid ecosystems, which have been introduced as fragile and vulnerable habitats. In the present study, labile contents of soil organic matter (SOM), microbial and enzymatic indices under the influence of forest and rangeland cover [i.e. natural forest with dominant species of Zelkova carpinifolia (Pall.) K. Koch. And three rangeland covers, converted form forest site almost 30 years ago, with dominant species of Festuca ovina L. Dactylis glomerata L. and Stachys byzantina K. Koch.] in Northern Iran have been considered including seasonal changes. The study aimed to investigate i) the effect of forest conversion to rangelands on SOM fractions, (ii) temporal dynamics of soil microbial processes and enzyme functions in different vegetation types, and (iii) determining the relationship between indices related to the content of organic matter and the size of microbial population in mountain ecosystems. Results showed that Zelkova tree type enhanced the levels of SOM contents, carbon and nutrient (nitrogen, phosphorous, potassium, calcium and magnesium) pools, and also with higher values in the summer season, the size of microbial population and processes. Additionally, the SOM turnover and microbial efficiency were almost suppressed in order to Zelkova > Festuca > Dactylis > Stachys vegetation types, respectively. Based on the obtained results, it can be concluded that the presence of tree cover in mountain ecosystems can strengthen soil function and create fertile islands. Therefore, the protection of natural forests is emphasized for the proper management and sustainability of habitats in semi-arid regions., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The objective of the present study was to evaluate how altitudinal gradients shape the composition of soil bacterial and fungal communities, humus forms and soil properties across six altitude levels in Hyrcanian forests. Soil microbiomes were characterized by sequencing amplicons of selected molecular markers. Soil chemistry and plant mycorrhizal type were the two dominant factors explaining variations in bacterial and fungal diversity, respectively. The lowest altitude level had more favorable conditions for the formation of mull humus and exhibited higher N and Ca contents. These conditions were also associated with a higher proportion of Betaproteobacteria, Acidimicrobia, Acidobacteria and Nitrospirae. Low soil and forest floor quality as well as lower bacterial and fungal diversity characterized higher altitude levels, along with a high proportion of shared bacterial (Thermoleophilia, Actinobacteria and Bacilli) and fungal (Eurotiomycetes and Mortierellomycota) taxa. Beech-dominated sites showed moderate soil quality and high bacterial (Alphaproteobacteria, Acidobacteria, Planctomycetes and Bacteroidetes) and fungal (Basidiomycota) diversity. Particularly, the Basidiomycota were well represented in pure beech forests at an altitude of 1500 m. In fertile and nitrogen rich soils with neutral pH, soil quality decreased along the altitudinal gradient, indicating that microbial diversity and forest floor decomposition were likely constrained by climatic conditions., (© The Author(s) 2020. Published by Oxford University Press on behalf of FEMS.)

The effect of vegetation types at mountainous sites on the relationships between soil biota and environmental variables applicable for the evaluation of soil quality and functions are barely studied and remain almost unknown. With the aim of studying the effect of shrubland and grassland plant coverings on soil fauna and flora activities, a mountainous semi-arid site in northern Iran (Diakooh) was selected for this research. Six vegetation types were selected with dominance in shrub and grassland coverage, i.e., (1) Crataegus microphylla CK. Koch., (2) Berberis integerrima Bunge, (3) Ribes uva-crispa L., (4) Prunus spinosa L., and with dominance in rangeland cover, i.e., (5) dominant Lecokia cretica (Lam.) DC., Orchis mascula L., Cardamine bulbifera (L.) Crantz, and (6) Fragaria vesca L. A total of 15 soil samples (30 × 30 × 10 cm) from each vegetation type were transferred to the laboratory. In addition, seasonal measurements (i.e. summer and autumn) were considered to achieve the temporal patterns of soil fauna and flora activities. Higher populations of soil earthworms (especially epigeic groups), acarina, collembola, nematode, and protozoa were found in the Crataegus site compared to other vegetation types with higher activities in the autumn season. Shrublands, especially with Crataegus cover, had increased activities of soil bacteria and fungi with higher abundances in the summer. Soils with higher fertility indicators and increased biota activities were attributed to the Crataegus and Berberis vegetation types by PCA. Overall, the findings of this study showed that shrubs can improve soil quality at high altitudes of mountainous, semi-arid sites that are often considered as especially fragile and sensitive ecosystems., (Copyright © 2019. Published by Elsevier B.V.)

Soil organisms, including earthworms, are a key component of terrestrial ecosystems. However, little is known about their diversity, their distribution, and the threats affecting them. We compiled a global dataset of sampled earthworm communities from 6928 sites in 57 countries as a basis for predicting patterns in earthworm diversity, abundance, and biomass. We found that local species richness and abundance typically peaked at higher latitudes, displaying patterns opposite to those observed in aboveground organisms. However, high species dissimilarity across tropical locations may cause diversity across the entirety of the tropics to be higher than elsewhere. Climate variables were found to be more important in shaping earthworm communities than soil properties or habitat cover. These findings suggest that climate change may have serious implications for earthworm communities and for the functions they provide., (Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

This study investigated the interactions between tree-herb layer diversity and some physico-chemical and eco-physiological characteristics of soil in natural oriental beech stand in western Guilan, Iran. The data were collected from nine research sites (50 m × 50 m) which were described as a gradient from pure oriental beech (Fagus orientalis Lipsky) stands to mixed stands with up to nine deciduous tree species (n = 27) in Hyrcanian forest. Herbaceous plants were sampled within ten 1 m × 1 m sub-plots in two plots of 400 m 2 which were installed randomly in each research site. Composite soil samples were taken at five positions in each research site. We found that the increase in tree diversity in mature oriental beech stands brought about an increase in microbial biomass carbon, soil carbon content, and the ratio of microbial biomass carbon to the organic carbon (C mic /C org ). Increased soil organic carbon raised microbial biomass carbon through creating suitable environment for microorganisms. The findings also indicated that the ratio of microbial biomass carbon to the organic carbon (C mic /C org ) increased as a quantitative indicator of soil carbon dynamics that finally benefits soil fertility of mixed oriental beech stands compared to pure oriental beech stands. The results showed that humus layer and litter thickness were negatively correlated with tree layer richness. Generally, it can be stated that maintaining a mixture of tree layer species in natural oriental beech stands results in an increase in richness and diversity values of herb plants as well as carbon content and microbial biomass carbon of soil.

Conversions of land use/cover are associated with changes in soil properties and biogeochemical cycling, with implications for carbon (C), nitrogen (N), and trace gas fluxes. In an attempt to provide a comprehensive evaluation of the significance of different land uses (Alnus subcordata plantation, Taxodium distichum plantation, agriculture, and deforested areas) on soil features and on the dynamics of greenhouse gas (GHG) fluxes at local scale, this study was carried out in Mazandaran province, northern Iran. Sixteen samples per land use, from the top 10 cm of soil, were taken, from which bulk density, texture, water content, pH, organic C, total N, microbial biomass of C and N, and earthworm density/biomass were determined. In addition, the seasonal changes in the fluxes of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) were monitored over a year. Our results indicated that the different land uses were different in terms of soil properties and GHG fluxes. Even though the amount of the GHG varied widely during the year, the highest CO2 and CH4 fluxes (0.32 mg CO2 m(-2) day(-1) and 0.11 mg CH4 m(-2) day(-1), respectively) were recorded in the deforested areas. N2O flux was higher in Alnus plantation (0.18 mg N2O m(-2) day(-1)) and deforested areas (0.17 mg N2O m(-2) day(-1)) than at agriculture site (0.05 mg N2O m(-2) day(-1)) and Taxodium plantation (0.03 mg N2O m(-2) day(-1)). This study demonstrated strong impacts of land use change on soil-atmosphere trace gas exchanges and provides useful observational constraints for top-down and bottom-up biogeochemistry models.

The effects of soil pedoturbation (i.e., pit and mound microtopography, PM) on development of herbaceous plant species and woody species regeneration were examined in a temperate beech forest (Fagus orientalis Lipsky) in northern Iran. We recorded the vegetation in 20 pairs of disturbed and adjacent undisturbed plots and established a chronosequence of PM ages to study the effect of time since microsite formation on cover percent of herbaceous plants and woody regeneration status. According to our findings, Carex acutiformis L., Sambucus ebulus L., Brachypodium pinnatum L., and Cyclamen coum L. are found only in the PM microsites, whereas the Equisetum ramosissimum L. is recorded only under closed canopy. The coverage percent of Rubus caesius L. increased in PM microsites compared to closed canopy intensively. In addition, Albizia julibrissin Durazz. is detected in PM microsite, whereas the Acer cappadocicum B. and Prunus persica L. species were recorded only under closed canopy. We found significant differences in understory species diversity between different ages of PM, and disturbed and adjacent undisturbed plots. Our study supports that the PM complex will create a mosaic of environmental conditions. This environmental heterogeneity could be responsible for the diversity of herbaceous plant species and regeneration of woody species.

Following the ratification of the Kyoto Protocol, afforestation of formerly arable lands and/or degraded areas has been acknowledged as a land-use change contributing to the mitigation of increasing atmospheric CO(2) concentration in the atmosphere. In the present work, we study the soil organic carbon sequestration (SOCS) in 21 year old stands of maple (Acer velutinum Bioss.), oak (Quercus castaneifolia C.A. Mey.), and red pine (Pinus brutia Ten.) in the Darab Kola region, north of Iran. Soil samples were collected at four different depths (0-10, 10-20, 20-30, and 30-40 cm), and characterized with respect to bulk density, water content, electrical conductivity, pH, texture, lime content, total organic C, total N, and earthworm density and biomass. Data showed that afforested stands significantly affected soil characteristics, also raising SOCS phenomena, with values of 163.3, 120.6, and 102.1 Mg C ha(-1) for red pine, oak and maple stands, respectively, vs. 83.0 Mg C ha(-1) for the control region. Even if the dynamics of organic matter (OM) in soil is very complex and affected by several pedo-climatic factors, a stepwise regression method indicates that SOCS values in the studied area could be predicted using the following parameters, i.e., sand, clay, lime, and total N contents, and C/N ratio. In particular, although the chemical and physical stabilization capacity of organic C by soil is believed to be mainly governed by clay content, regression analysis showed a positive correlation between SOCS and sand (R = 0.86(**)), whereas a negative correlation with clay (R = -0.77(**)) was observed, thus suggesting that most of this organic C occurs as particulate OM instead of mineral-associated OM. Although the proposed models do not take into account possible changes due to natural and anthropogenic processes, they represent a simple way that could be used to evaluate and/or monitor the potential of each forest plantation in immobilizing organic C in soil (thus reducing atmospheric C concentration), as well as to select more appropriate species during forestation plan management at least in the north of Iran.

Earthworms are considered as soil engineers because of their effects on soil properties and their influence on the availability of resources for other organisms, including microorganisms and plants. However, the links between their impacts on the soil environment and the resulting modification of natural selection pressures on engineer as well as on other organisms have received little attention. Earthworms are known to have a positive influence on the soil fabric and on the decomposition and mineralization of litter by breaking down organic matter and producing large amounts of fasces, thereby mixing litter with the mineral soil. Therefore, they play an important part in changes from one humus from to another according to forest succession patterns. Consequently, they are also expected to be good bio-indicators for forest site quality and are thus useful when planning forest production improvement. Earthworm's populations are as indicator that in exploited regions is destruction indicator and reclamation plans is nature return indicator. In this study we summarized the current knowledge in relation to earthworm's ecology in forest soils as ecosystem engineers.

A TWINSPAN classification of 60 sample plots from the Khanikan forest (North of Iran) is presented. Plant types were determined from field observations and sample plot data arranged and analyzed in association tables. The types were defined on the basis of species patterns of presence, absence and coverage values. Vegetation was sampled with randomized-systematic method. Vegetation data including density and cover percentage were estimated quantitatively within each quadrate and using the two-way indicator species analysis. The objectives of the study were to plant type's classification for Khanikan lowland forest in North of Iran, Identification of indicator species in plant types and increase our understanding in regarding to one of Multivariate analysis methods (TWINSPAN). Five plant types were produced for the study area by TWINSPAN, i.e., Menta aquatica, Oplismenus undulatifolius, Carex grioletia, Viola odarata and Rubus caesius. Therefore, at each step of the process, the program identifies indicator species that show strongly differential distributions between groups and so can severe to distinguish the groups. The final result, incorporating elements of classification can provide a compact and powerful summary of pattern in the data set.

This research was conducted in Khanikan forests located in lowland of Mazandaran province (North of Iran). Eighteen profiles were dug and several chemical, physical and biological soil properties were investigated. The soil properties evaluated were soil pH, bulk density, saturation moisture content, electrical conductivity, organic carbon, total nitrogen, cation exchangeable capacity, available phosphorous, soil texture, calcium carbonate content, number and biomass of earthworms, litter carbon and litter nitrogen. Principal Component Analysis (PCA) was used to identify the variation of soil properties. PCA, a technique which reduces the dimensionality of multivariate data by removing Interco relations among variables, has a number of useful applications in forest researches. The results showed significant relationships between some soil factors with PC1 and PC2 axes, also, among different soil factors, the distribution of forest types was most strongly controlled with some soil characteristics such as acidity, bulk density, texture, phosphorous, organic carbon, total nitrogen and cation exchangeable capacity.

In order to make the sampling procedure more efficient and more accurate to study the tree species richness and canopy cover, the appropriate plot size was calculated in the this study. The sampling was carried out using 48 four-hectare plots, each with 13 sub-plots of different plot sizes and 7 one-hectare plots, each with 7 sub-plots. The result of this study showed that 300 ARE plot size was determined as the best area for 1-5% density class, 125 ARE plots for 5-10% class, 150 ARE for 10-25% class, 100 ARE for 25-50% class and 75 ARE plot size to sample >50% density class, in 95% confidence level. Consequently, using 100 ARE sampling plots is suggested for all density classes in central Zagros forests.

Zarbin (Cupressus sempervirence var. horizontalis) with its unique characteristics is one of the worthiest species which can be found in the central area of Alborz in the North of Iran. Especially in the Roodbar-manjil area, Chaloos-Hassanabad valley as well as it extends from Zarringol area to Gorgan. Although the distribution areas of this species have been protected, these forests have been invaded by the villagers who use this useful wood. For this reason in the Roodbar area, trees with DBH>30 cm are extremely rare. To recognize and to be aware of the stand quantity, the current research tries to calculate the species volume table in Roodbar area, to be the basis for any calculation of the volume of stand in the region. For this purpose, trees have been sampled using the line sampling method. After estimating the form factor, Tarif table have been prepared. In this study, a new method for measuring tree height is presented, in which, instead of measuring slope distance from observer to tree (which is difficult in young conifers because of existence branches in lower height) distance between the eye level of observer to tree butt is measured. Which doing of it is easier, time of field work is decreased and accuracy of measurement and calculation is increased.

Primary transportation is an upper time, expensive and hard labour. The most skidding are with using of rubber wheel of Timber jack 450C in Iran country that has devoted 60% of utilization expenses. In order to, investigate of slope and loading volume effects on time of loaded traveling had used time study for Timberjack 450C. In one of strip roads in parcel eleven of district two of Langa management plan forest (Kelardasht region in North of Iran) determined 5 and 3 different slopes classes and volumes classes, respectively. Then, time study was performed in slope classes with different loading volume in downward skidding. The first, collection of data have noted in special form and then have converted to uniform unit of m sec(-1). Descriptive statistics for each data set were calculated using the SPSS software. With presupposition that loading volume and slope are effective on the obtained time, these parameters have analyzed. ANOVA and Tukey test were used for loading volume factor. For investigation slope factor had used of Mann Whitney non-parametric test in order to comparison of loaded traveling speed in different slopes. Results of present research had showed that influence of loading volume on the loaded traveling time is insignificant, but loaded traveling speed in different slope classes is significant (in slopes >30%) as, speed of skidder machine is decreased with increase of slope variable.