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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.

The purpose of this study is to investigate the effect of cellulosic wastes and nanoscale zero-valent iron (nZVI) on the soil properties and the nutrient uptake by Quercus castaneifolia C.A.Mey see...

Dead trees, and particularly downed logs, play an important role in the dynamics of forest ecosystems. The contribution of decaying wood to the carbon and nutrient pool of forest soils depends on tree species and the degree of wood decay but the extent to which downed logs affect forest properties in temperate forests has rarely been quantified. In order to investigate the impact of decaying wood on soil properties, we carried out a study in a mixed beech forest of the Liresar district (Mazandaran province, northern Iran). We first investigated if and how the presence of downed logs affects soil quality and function by comparing soils underneath degraded logs and nearby soils of the two dominant forest species, beech and hornbeam. Then, we explored how these effects occur as downed logs decompose by comparing wood with four degrees of decomposition of both tree species. The decay degree of downed logs was classified in four classes (DC1 to DC4). Eight dead trees of each tree species were selected as the center of each sample plot and three composite soil samples under each decaying log and 100 cm near a decaying log (soil around logs) were collected at two soil depths (i.e., 0–15 and 15–30 cm) and then analyzed for main physico-chemical characteristics and microbial activity. Our study showed that downed logs affected physical (5% wetter than control soils), chemical (lower by 2% the pH, increased 100% organic C, and total N in the case of hornbeam and P by 2%) and biological (i.e., soil microbial respiration was enhanced by 10% and , microbial biomass of C 620 mg kg−1, 351.5 mg kg−1 and N 66.47 mg kg−1, 32.18 mg kg−1 by, respectively) characteristics of soils, thus resulting in downed tree soil microsites that strongly differ from those without downed logs. The presence of down logs increased soil microbial activity and soil fertility as wood decayed. Thus, the presence of downed logs should be considered as an important factor influencing forest soils and should be taking into account in forest management practices.

The objective of the study was to examine changes in microbial parameters have been used to monitor changes in soil quality under different land uses in north of Iran. The microbial parameters included microbial respiration (MR), substrate induced respiration (SIR), carbon availability index (CAI), microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), ratio of MBC/MBN, metabolic quotient (qCO2) and microbial ratio were determined under different land use/cover, i.e. virgin natural forest (VNF), degraded natural forest (DNF), alder plantation (AP), sequoia plantation (SP), improved fallow (IF) and home garden (HG) areas in northern Iran. Five composed samples per land use/cover were taken from the top 10 cm of the soil. MR and SIR (0.45 and 1.66 mg CO2-C g−1 day−1, respectively) were found to be significantly higher under AP land uses than in the other areas. CAI did not differ for the land uses; MBC (591 and 590 mg kg−1, respectively) had higher significantly under SP and VNF land uses than in the other areas. MBN (64.25 and 62.33, respectively mg kg−1) was significantly higher in AP and VNF land uses, ratio of MBC/MBN (17.02) was higher in SP land use than other areas, HG had significantly higher qCO2 (0.0012 μg CO2-C mg−1 MBC day−1) and finally microbial ratio was significantly higher under IF (599.16) in comparison with HG > AP ≈ DNF > VNF > SP areas. Overall, our results indicate that AP land use (Alnus subcordata C. A. Mey.) increase of soil quality and alder plantation is suitable for rehabilitation of degraded natural forests.

Microbial activity of top soils is directly linked with carbon (C) and nitrogen (N) turnover in terrestrial ecosystems, and thus is an indicator to identify hot spot areas of C and N cycling in forest habitats. The Hyrcanian forests are one of the last remnants of natural deciduous forests in the world and Oriental Beech (Fagus orientalis Lipsky) is one of the most abundant tree species of these forests. It has not been resolved which forest properties of Hyrcanian forests facilitate hotspots with high microbial process rates. We studied those primary causes (i.e. forest properties) of changes on soil characters and processes within old-growth Vaz forests, Northern Iran, and separately sampled different landform positions (i.e. catena, pit-mound and gilgai), single-trees, deadwoods and canopy gaps. Principal component analysis (PCA) of the 31 soil parameters resulted in two principal components that explained more than 60% of the total variance. The first component (PC1) explained the highest variance (48.13%) in the results; while second component (PC2) accounted for 13.68% of the variance. The obtained PCA results indicate a clear differentiation in selected soil properties among forest properties and thus, three groups of drivers for microbial activities were identified. Group 1 (foot and toe slope of V-shape catena, toe slope ofΛ-shape catena, pit structure of hornbeam, decay class 4 of beech deadwoods, small and medium canopy gaps) enhanced soil microbial process and enzyme activities. Group 2 (pit structure of beech, control or non-gilgai position, beech and hornbeam single-trees, decay class 3 and 4 of hornbeam deadwoods and large canopy gap) enhanced soil microbial biomass and greenhouse gas fluxes. Group 1 and 2 drivers were associated with high values of soil water content, organic C, total N, available nutrients, organic matter fractions, earthworm and nematode activities. Group 3 drivers (summit and shoulder slope of V- and Λ-shape catena, back slope of V-and Λ-shape catena, foot slope ofΛ -shape catena, mound of beech and hornbeam, position in a gilgai, decay class 2 and 3 of beech deadwoods, decay class 1 and 2 of hornbeam deadwoods and very large canopy gap) correlated with lowest microbial activities and was associated with high values of soil bulk density, pH, electrical conductivity and C/N ratio. Thus, distribution of microbial hotspot areas in the Hyrcanian forests can be considered as mosaic of pedons characterized by specific sets of key parameters, which depend on landform, especially the toe slope of V-shape catena, and stand characteristics (e.g. tree species or canopy gap).

International audience; The relationships between woody species, soil biota activity and soil quality were largely ignored in semi-arid areas. This study evaluated the influence of life form and seasonal variation on the mesofauna activity and soil chemical and microbial properties under three tree species (Quercus brantii (QU), Acer monspessulanum (AC) and Pistacia atlantica (PI), and three shrub species (Crataegus puntica (CR), Amygdalus scoparia (AM) and Lonicera nummularifolia (LO)) in a semiarid oak forest in western Iran. Soils were sampled beneath each individual woody species in spring and winter. Soil chemical and biological properties and soil mesofauna diversity were measured and soil quality index (SQI) was produced. The comparison of soil chemical properties under tree and shrub species showed that only soil total nitrogen (Ntot), available potassium (Kava) and soil organic carbon (SOC) were significantly higher under trees than shrubs (respective mean values for spring: 0.31 vs 0.19%; 1304 vs 1103 mg/kg, 3.94 vs 3.16%). In contrast, all of the studied soil biological characteristics including microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), basal respiration (BR), and substrate induced respiration (SIR) were significantly higher under trees than under shrubs (respective mean values for spring in mg/kg soil/day: 603.5 vs 431.2, 49.6 vs 35, 46 vs 35 and 57.6 vs 36.5). Besides, we found clear seasonal and species effects for most soil properties. Values were higher in spring than in winter and were the most similar for QU and AC for tree species (especially due to the higher content of SOC and MBN under these species in spring) and for AM and LO for shrub species. The Shannon-Wiener diversity index and richness of the soil mesofauna were significantly higher under trees than under shrubs (respective mean values for spring: 1.59 vs 1.09 and 6.5 vs 3.8). The Shannon-Wiener diversity and richness indices for soil mesofauna were positively linearly related to the soil quality index (SQI) in spring and winter. These relationships were weaker in winter than in spring and showed an increase of both indices from shrubs (LO, AM and CR) with low SQI values to trees (QU and AC) with higher SQI values. Based on these results, we conclude that these indices can be used as efficient soil bioindicators which can be helpful in restoration or conservation projects in semi-arid areas.

In temperate forests, oak (Quercus castaneifolia) is an important species that grows along an elevation gradient from the flood prone plains to high topographical positions of the landscape. This study was aimed to monitor the effect of oak plantation on the soil C and N cycles and dynamics in the north of Iran. We tested the following hypotheses: (i) reclamation of deforested areas, planting of oak can improve topsoil fertility via forest floor inputs in the long-term, (ii) soil C and N microbial indices can be enhanced under oak plantation, 25 years after planting. For this purpose, three afforested oak stands with 15, 20, and 25 years old, besides a site without plantation, were selected and thirty samples per each site were taken from forest floor and soil (20 × 20 × 10 cm) layers and their physicochemical, biological, and enzymatic properties were assessed. The acquired data demonstrated that forest floor quality, physicochemical and biological properties and enzymatic activities (i.e. urease, acid phosphatase, arylsulfatase and invertase) have been changed over time of oak plantation. Moreover, the microbial activity of soil C and N include basal respiration (BR), substrate inducted respiration (SIR), microbial biomass carbon (MBC), Metabolic quotient (qCO2), microbial entropy (MBC/C), carbon availability index (CAI), carbon management index (CMI), particle organic carbon (POC) and dissolved organic carbon (DOC) were significantly higher in the plantation areas than without plantation site. Oak plantation significantly improved the N microbial characteristics [NH4+, NO3−, N mineralization, microbial biomass nitrogen (MBN), particle organic nitrogen (PON) and dissolved organic nitrogen (DON)]. Under different land covers, soil microbial activities were more affected by variations in forest floor and soil chemical properties with higher ratio of C, N and available nutrients. Taken together, plantation with suitable native broadleaved species could be considered to rehabilitate degraded natural forests through improving soil quality. Findings also highlighted the importance of understanding C and N cycles in the plantation areas which could involve in global warming phenomena.

The characteristics of the faunal community in the soil are closely related to soil quality and function. Land degradation, which reduces vegetation cover, may affect the soil surface-active fauna because both the above ground and below ground invertebrates depend on complex plant communities. In this study, we evaluated the effect of land degradation/restoration and factors affecting soil fauna in northern Iran. The studied land uses were virgin natural forest (VNF), Alnus subcordata C.A.M. plantation (ASP), Quercus castaneifolia C.A. Mey plantation (QCP), Cupressus sempervirens var. horizontalis plantation (CSP) and degraded natural forest (DNF). VNF and ASP enhanced soil earthworm density (2.43 and 2.12 ind. m−2) and dry mass (27.44 and 23.39 mg m−2) with more ratio of epigeic. The activities of acarina (91,851.37 and 85,810.43 ind. m−2), collembola (83,009.50 and 74,996.18 ind. m−2) and protozoa [921.25 and 851.81 (× 102 g soil)] were increased under VNF ≈ ASP, respectively. Nematode population (650 in 100 g soil) significantly improved under VNF. In general, good quality forest floor, alkaline soil and accumulation of macro-element nutrients improved biological activities under the VNF and ASP sites, while low-quality forest floor, acidic soil, less macro-elements nutrients decreased biological activities imposed by the QCP, CSP and DNF sites. More activities of the studied soil fauna were found in autumn and spring. The findings of this study support the importance of preserving natural forests. In addition, employing N2-fixing and suitable native broadleaved species have been proposed in a bid to rehabilitate DNFs.

Temperate forest productivity and functioning may be explained by complex interactions among tree canopy composition, topographic conditions, climate, morphogenetic identification and classification of humus forms. In this study, we report the main morphological feature of humus profiles classified according to both American (AHCM) and European (EHCM) classifications under the six most common forest stands in northern Iran, i.e., Alnus subcordata (AS), Acer velutinum (AV), Fagus orientalis-Carpinus betulus (FO-CB), Carpinus betulus (CB), Fagus orientalis (FO), and Fagus orientalis-Carpinus betulus-Parrotia persica (FO-CB-PP). Organic and organic-mineral layers samples were collected in 61 permanent plots (20 × 20 m) within a 30 × 30 cm metal frame, for identification. Our result showed that Mull was the dominant humus system according to both classifications, whereas Mor (AHCM) and Amphi (EHCM) were the less frequent humus systems in the study area. Mull and Amphi (EHCM) were dominant at the lowest slope and altitude under AS canopy cover; Moder was usually present at intermediate slope and altitude under FO-CB and FO-CB-PP; while Mor was the dominant form at intermediate slopes and highest altitudes under FO and FO-CB. Due to the temperature changes and litter decomposition, altitude seems to be the best predictor of humus type and litter thickness. Our findings also indicate that EHCM could be preferred in the identification and classification of humus forms in temperate deciduous forests in Iran.

Our findings show the differential impacts of tree types (hornbeam–ironwood natural forest and plantations of ash, maple, cypress and pine) on soil physical–chemical characteristics and how dominant tree species regulate the size and activity of soil microbial and enzymes. Soil microbial and enzyme activities have an important influence on nutrient cycling. The variation in soil carbon (C) and nitrogen (N) microbial indices as well as enzyme activities were determined under hornbeam–ironwood natural forest and 25-years old plantations of ash, maple, cypress and pine in northern Iran. Four soil profiles were dug along the four parallel transects in the central part of each forest stand, resulting in 16 soil samples for each stand at a depth of 0–15 cm. The results showed significant differences in most of studied soil physico-chemical properties among different land covers. Soil microbial basal respiration (MR) and substrate induced respiration (SIR) were found to be significantly higher under natural forest than in the plantation stands. Microbial biomass C (MBC) did not differ for the forest stands, whereas natural forest had significantly higher qCO2 (MR: MBC), microbial entropy (MBC: Corg) and C availability index (MR: SIR) values. The establishment of plantations reduced the values of soil microbial biomass N, mineral nitrogen (NH4–N and NO3–N) and N mineralization with the least under coniferous stands of cypress and pine, while greater amounts were observed under natural forest. With replacement in the type of tree species from natural forest to plantations, acid phosphatase, arylsulphatase and invertase enzyme activities decreased significantly in the topsoil, whereas like natural forest, ash plantation improved urease enzyme. This research recommends conservation of natural forests for increase of soil quality and plantation of suitable native broad-leaved species for rehabilitation of degraded natural forests.

Context The process of establishing a mixed canopy composition by intermingling individuals of beech, hornbeam, and maple is an ongoing trend in adaptive forest management strategies. However, our understanding of the potential of these strategies to promote forest floor and soil quality remains limited. Aims Beech ( Fagus ) is one of the most valuable industrial species in Iran, which is present in combination with other tree species with different effects on soil fertility. This study measures the role of different canopy compositions of beech trees, including mixed beech (beech-maple-hornbeam), beech-hornbeam, beech-maple and pure beech on forest floor quality, soil features and C and N cycles of the Hyrcanian forest in Iran. Methods Five replicates are regarded for each canopy composition and a total of 20 permanent plots were considered in the forest. Four forest floor and soil samples, with an area of 25 cm × 25 cm, were taken from 0 to 15 cm depth under each canopy cover and a composite sample for each plot (for forest floor and soil separately) was transferred to the laboratory. Forest floor (C, N and thickness) and soil physico-chemical (water content, bulk density, aggregate stability, pH, EC, organic C, total N, available P, K, Ca and Mg), biological (earthworm biomass/density, nematode density, fine root biomass, N mineralization and basal respiration or BR), biochemical (NH 4 + and NO 3 − concentrations, substrate induced respiration or SIR, particulate organic matter C - N or POM-C and POM-N, dissolved organic C - N or DOC and DON), soil aggregate size (macro and micro) features and soil enzyme activity (urease, acid phosphatase, arylsulphatase and invertase) were measured. Results Mixed composition of canopy cover had the highest forest floor quality, with the greatest amount of N and the lowest of C. The highest amounts of soil aggregate stability, pH, total N and available nutrients were found in the mixed composition and the highest amounts of water content, organic C and C/N ratio, with the least of soil bulk density, were observed under pure beech. In general, higher values of earthworm density/biomass, nematode density, fine root biomass, N sequestration and mineralization, NH 4 + , NO 3 − , BR, SIR, POM-N, DON, macro aggregate, N in macro- and micro-aggregates and enzyme activity were observed in the mixed beech compared to the other canopy composition. The highest values of POM-C, DOC, C in macro- and micro-aggregates were found under pure beech canopy than in mixed beech composition. The lowest value of the C availability index (CAI) was found under pure beech canopy cover. C sequestration of different tree compositions did not show any statistically significant difference. Conclusion The influence of trees on forest floor and soil features is detectable even in a mixed stand and the soil landscape experience a mosaic of changes, reflecting the chemical characteristics of the various tree species present in the stand. Our results suggest that the composition of tree species can change the forest floor quality, soil fertility and microbial activities related to C and N in mixed forests. As a conclusion, increasing the soil quality by tree species composition – employing hornbeam and maple for amending the forest soils with accompanying beech can be suggested in pure beech stand.

Few studies have analyzed how tree species within a mixed natural forest affect the dynamics of soil chemical properties and soil biological activity. This study examines seasonal changes in earthworm populations and microbial respiration under several forest species (Carpinus betulus, Ulmus minor, Pterocarya fraxinifolia, Alnus glutinosa, Populus caspica and Quercus castaneifolia) in a temperate mixed forest situated in northern Iran. Soil samplings were taken under six individual tree species (n = 5) in April, June, August and October (a total of 30 trees each month) to examine seasonal variability in soil chemical properties and soil biological activity. Earthworm density/biomass varied seasonally but not significantly between tree species. Maximum values were found in spring (10.04 m−2/16.06 mg m−2) and autumn (9.7 m−2/16.98 mg m−2) and minimum in the summer (0.43 m−2/1.26 mg m−2). Soil microbial respiration did not differ between tree species and showed similar temporal trends in all soils under different tree species. In contrast to earthworm activity, maximum microbial activity was measured in summer (0.44 mg CO2–C g soil−1 day−1) and minimum in winter (0.24 mg CO2–C g soil−1 day−1). This study shows that although tree species affected soil chemical properties (pH, organic C, total N content of mineral soils), earthworm density/biomass and microbial respiration are not affected by tree species but are controlled by tree activity and climate with strong seasonal dynamics in this temperate forest., This work was done by financial support of Tarbiat Modares University, Tehran, Iran.

Water stress is one of the most important environmental stresses which can adversely affect soil fertility and plant growth in arid and semiarid regions. In this study, biochar was used as a type of soil amendment to improve the physiology of Chestnut-leaved oak (Quercus castaneifolia C.A.M.) seedlings and soil quality in water-deficit conditions. A randomized complete block design was conducted using three water regime treatments [100, 70 and 40% field capacity (FC)] and four application rates of produced biochar from hornbeam wood chips (control without biochar, B1, B2 and B3 with 10, 20 and 30 g kg−1 soil, respectively) in potted seedlings. The soil water-holding capacity in the 30 g kg−1 biochar was found to be higher than that in the non-biochar treatment under 100 and 40% FC. Water supply reduction to 40% FC decreased the soil total N, the available P and K, CEC, SOC and microbial respiration, as compared to the non-biochar soil used as the control; however, an increase in the B3 treatment was detected in the soil P and K at 100% FC. Severe water deficit (40% FC) induced a significant decrease in photosynthesis, transpiration, stomatal conductance and xylem water potential seedlings; even, in this case, the addition of the highest dose of biochar under the lowest water supply increased photosynthesis and stomatal conductance by 38% and 39%, respectively. Leaf nutrient concentration was also influenced by the treatment. The highest diameter and height growth and dry weight of the seedlings were observed in 100 and 40% FC under the B3 treatment. Plant biomass of the seedlings treated by B3 was increased by 55, 70 and 73%, in comparison with those attained by the control under 100, 70 and 40% FC irrigation, respectively. Generally, the use of the 30 g kg−1 biochar in the soil could alleviate the negative effects of water deficit and improve the growth of Q. castaneifolia seedling and soil quality with increasing the soil water-holding capacity, organic carbon and nutrient.

Tree influence on litter and soil features is detectable even in a mixed stand and the soil landscape may be considered as a mosaic of profiles reflecting the occurrence and chemical characteristics of the various tree species present. The forest soils can be strongly influenced by tree species. Many studies have addressed the effects of monocultures on soil features, but few have examined the effects of individual trees within a mixed stand. This work illustrates the differences of litter and soil characteristics in a coastal mixed forest stand in northern Iran. For this purpose, the Alnus glutinosa (AG), Populus caspica (PC), Ulmus minor (UM) and Parrotia persica (PP) species were examined; litter and soil samples were taken under tree canopy cover. Litter quality differed among the tree species, with the highest total N concentration (1.83%) and lowest organic C (38.38%) under AG species. Soil pH (7.19), EC (0.29 ds/m), total N (0.33%), available P (26.21 mg kg−1), available Ca (257.30 mg kg−1), available Mg (56.80 mg kg−1), earthworm density/biomass (4.00 n m−2 and 49.47 mg m−2, respectively), microbial respiration (0.49 mg CO2–C g soil −1 day−1), net soil ammonification (0.44 mg kg−1 day−1) and N mineralization rate (0.30 mg kg−1 day−1) were significantly higher under AG canopy whereas a higher content of available K (355.80 mg kg−1) and fine root biomass (95.02 g m−2) were found under the PC and UM tree species, respectively. Soil organic carbon and net soil nitrification were not significantly different among tree species. The results of this case study demonstrate that tree influence on litter and soil features is detectable even in a mixed stand and the soil landscape of such forests may be considered as a small-scale mosaic of profiles reflecting the occurrence and chemical characteristics of the various tree species present.

We examined the variation in woody plant species composition, regeneration and biodiversity in relation to topographic heterogeneity, specifically catena shape (V and Λ) and slope position (summit, shoulder, back slope, foot slope and toe slope). All research took place at the TMU Experimental Forest Station, located in northern Iran. Two sets of replicated quadrats were established along transects that encompassed the different catena shapes and positions. We recorded the density, height, and canopy cover of all trees ≥12 cm diameter at breast height within 30 quadrats (400m2), as well as the density of all tree regenerations within 120 quadrats (4m2). In addition, three measurements of biodiversity were calculated for both mature trees and regenerations. Mature tree species composition varied greatly with catena shape and slope position, as did that of regenerating trees. Despite differences in species composition, the various measurements of biodiversity were consistent across the landscape for...

Human activities, such as tree cutting and land-use change, have significantly altered the forests of Iran's Zagros Mountains. In plantation projects within these forests, maintaining soil structure and fertility is necessary for sustainable forest management. Ideally, the soil quality of tree plantations should be as good as that of natural forests. In this study, we investigated the long-term impact of land-use change, i.e. conversion of natural oak forest to tree plantations or cultivated fields, on soil quality (i.e., physicochemical, biological and biochemical soil properties) in the forests of the Zagros Mountains. We found that the conversion of natural oak forest to tree plantations (in this case Cupressus arizonica, Cedrus libani, Elaeagnus angustifolia, Quercus brantii (persica), Robinia pseudoacacia and Fraxinus rotundifolia) and agriculture caused declines in soil organic carbon content, especially in the cultivated fields where it fell by around 60%. Overall, the lowest contents of soil nutrients, except Cu, were measured in agricultural soils. Interestingly, the plantation of a non-native tree (Cedrus libani) sequestrated more atmospheric carbon and nitrogen than native Persian oak forests. The impact on soil biological activity remains unclear: the conversion of natural forests into cultivated fields reduced soil biological activity, while conversion from forest to tree plantations had little influence. Finally, the conversion of natural forest to tree plantations had less impact on soil properties than conversion to cultivated fields. In conclusion, to maintain soil fertility, forest managers should avoid forest conversion to agriculture. Moreover, we do not recommend plantation of Cupressus arizonica in the Zagros region for the purpose of carbon and nitrogen sequestration and the increase of soil productivity.

Foresters always emphasize the understanding of soil properties in evaluating site capacity to support productive forests. In order to conserve and improve soil quality and functions, sophisticated forest management systems are of particular importance. Hyrcanian forests of Iran have been harvested under different silvicultural operations such as shelterwood and selective cutting systems. So far, no studies have been conducted to explore the effects of forest management systems on soil properties in this ecosystem. Consequently, the present study aimed to investigate the impact of shelterwood and single-tree cutting systems on soil quality and functions (i.e. organic matter fractions, biota and microbial/enzyme activities), 10 and 20 years after employing these systems in Hyrcanian beech stands, compared to intact forests (control areas). A total of 60 soil samples (30 × 30 × 10 cm) including 30 samples in August 2008 and 30 samples in August 2018 from each site (i.e. control areas, shelterwood and single-tree systems) were transferred to the laboratory. In addition, topsoil water content, temperature and biological dynamics (August 2008, November 2008, August 2013, November 2013, August 2018 and November 2018) were monitored across the different forest management systems. Based on our data, the studied forest sites and soil properties could be separated by PCA output. The first and second axes, respectively, accounted for 38.59 and 10.95% of the explained variance. The control areas enhanced soil organic matter fractions, biota and microbial/enzyme activities. Between different silvicultural operations, the single-tree system, which is considered as a close-to-nature system, has provided better conditions for soil quality and functions as compared to the shelterwood management system. The understanding of ecological changes within widespread forest management systems can be helpful in forest management and plays a significant role in evaluating silvicultural systems.

Soil organic matter (OM) stratification and macro and micro fauna are both good indicators for the evaluation of soil ecological functioning, which is interrelated with nutrient cycles. To the best of the authors’ knowledge, responses of the degree of OM stratification with soil depth expressed as a ratio, and belowground biota to forest degradation and land cover changes have received little attention, particularly in northern Iran. In this study, five land covers were selected: virgin natural forest dominated by Carpinus betulus and Parrotia persica (natural forest), mono-species oak stand (plantation), land including Citrus sinensis and Citrus tangerina trees (garden), land dominated by Brachypodium pinnatum and Carex sylvatica (rangeland), and land including rice cultivation (agriculture) to examine soil OM stratification ratio, biological dynamics, and nutrients. The aim of this study was to evaluate the effect of natural and anthropogenic sites of Hyrcanian region on soil functions following 32 years of land cover changes. Four soil profiles (25 × 25 cm) were dug along four parallel transects in the central part of each land cover plot. Thus, 16 soil samples for each site were sampled at a depth of 0−10 cm for different soil properties and two depths of 0–10 and 10−20 cm to measure the soil OM and calculate OM stratification ratio (OM surface soil/OM subsurface soil). Seasonal measurements during one year were performed under studied land covers to find the temporal pattern of the soil biological activities. With a descending trend of OM with soil depth, OM stratification ratio was significantly enhanced under plantation and natural forest. Conversion of natural forest to anthropogenic sites significantly decreased the activities of different earthworm ecological groups (i.e., epigeic, anecic, and endogeic), Acarina, collembola, nematode, protozoa, bacteria, and fungi. Two-way ANOVA indicated that in addition to land cover, the season also affected the variability of soil earthworm activities. Compared to the other studied soil organisms, the role of land covers was nearly 1.5–2 times greater than that of the season factor. From the PCA output, the high soil biological activities, OM stratification ratio, and nutrients can be attributed to forest ecosystems (i.e., natural forest and plantation), while the low soil biological activities, OM stratification ratio, and nutrients were imposed by anthropogenic sites (i.e., rangeland, garden, and agriculture). The findings of this study support the importance of preserving natural forests for soil conservation and function.

This study focuses on the morphological and chemical development of humus forms as a function of altitude and forest type in the Northern Iran. Terrestrial humus forms related to European Humus Group proposal (EHGP) were evaluated under six common forest types, i.e. Alnus subcordata (AS), Acer velutinum (AV), Fagus orientalis - Carpinus betulus (FC), Carpinus betulus (CB), Fagus orientalis (FO) and Fagus orientalis - Carpinus betulus - Parrotia persica (FCP) stands with different topographic conditions. Within 61 permanent plots, organic (OL, OF, OH), organic-mineral (Ah) and mineral (soil A 0–15; first 15 cm under Ah) layers were collected for identification and chemical analyses. Our results support the idea that altitude and species composition were the two major factors controlling the presence of the different humus forms and their chemical characteristics. While mull was mainly observed at the lowest altitude under AS, moder was usually present at middle altitude under FC and FCP and mor dominated at the highest altitude under FO and FC. Moreover, organic layer thickness also increased with altitude and was higher in the case of mor. On the contrary, the organic-mineral layer thickness was higher at the lowest elevations in the case of mull. The chemical composition of humus layers also differed among forest types. PCA analysis showed that AS and AV forest types were closely related with mull and amphi humus forms, pH, macro nutrients and soil C and N, while FO, FC, and FCP forest types were closely related with moder and mor humus forms, C:N ratio, slope and altitude.

Labile soil organic matter, which is an important supply of energy for soil micro-organisms, has been suggested as a sensitive indicator of soil organic matter (SOM). In this study, the effects of forest vegetation on forest floor thickness and quality, labile SOM fractions and soil properties were examined in five different forest ecosystems, such as beech-hornbeam-alder, beech-hornbeam, beech-alder, beech-oak, and pure beech in the Hyrcanian region, northern Iran. Each forest type was replicated three times. In each plot, six forest floors and soil samples were taken in a 30 × 30 cm area. Pure beech had always a higher forest floor thickness than the other studied forest types. Increase in tree diversity in beech forest type reduced forest floor C:N ratio, more than three-fold, compared to pure beech. Based on our data, the influence of forest type on labile SOM was generally higher in the 0–10 cm soil layer than in the 10–20 cm layer. Beech-hornbeam-alder and beech-alder forest types, with high quality of forest floor and more values of N fractions in labile SOM, increased soil biological activities and fertility whereas pure beech and beech-oak forest types, with lower quality of forest floor and more values of C fractions in labile SOM reduced soil biological activities and fertility. Based on the result, the abundance of beech influenced nutrient cycling via forest floor quality. This led to an increase in labile SOM and subsequent soil fertility through the admixture of broadleaf species into beech forests.

Windthrow, i.e. the felling of trees by wind, occurs continually in forest ecosystems. The uprooting of old trees creates multiple microsites (e.g. pit and mound landscape) that are the main source of soil heterogeneity. To determine the impact of pit and mound landscapes on soil features, a beech forest of the Langa district (Mazandaran province, Northern Iran) was studied. An area of 25 ha was considered for this study wherein three microsites were distinguished, including pit bottom (pit), mount top (mound) and level areas (closed canopy). In this area, 22 uprooted trees were also found. Soil samples were collected at different depths (i.e. 0–15, 15–30 and 30–45 cm) from all microsites and analysed. Our study shows that windthrow events should be considered as an important factor in influencing forest ecosystem, as they affect physical (i.e. density, texture and water content), chemical (i.e. pH, organic C, total N, cation exchange capacity and available nutrients) and biological (i.e. soil microbial respiration and earthworm density/biomass) characteristics of soil, thus resulting in pit and mound microsites that may strongly differ with respect to the closed canopy.

Kooch Y, SM Hosseini, Hojjati SM, Fallah A. 2013. Variability of soil physical indicators imposed by beech and hornbeam individual trees in a local scale. Biodiversitas 14: 25-30. The objective of our study was to determine if soil physical indicators could be related to the influence of the individual trees in stands of mixed species growing on steep slopes in the Hyrcanian forests of Iran. Research was conducted in a forest dominated by beech (Fagus orientalis Lipsky) and hornbeam (Carpinus betulus L.) interspread with the other deciduous tree species. Due to, twenty hectare areas of Experimental Forest Station of Tarbiat Modares University was considered in northern Iran. The positions of trees with diameter at breast height more than 45cm were recorded by Geographical Position System (GPS). Three single-trees (trees with canopy cover separated from other trees and covered distinguished space) considered for soil sampling from every tree species and diameter class as three replications. All of soil samples were excavated in north aspect and at the nearest point to tree collar for more precision. Soil samples were taken at 0-15, 15-30 and 30-45cm depths using auger soil sampler with 81cm2 cross section. The result of this research showed that bulk density was significantly greater under beech than under hornbeam. This character tends to be less in 0-15cm depth than in 15-30cm and 30-45cm depths. Variable amounts of this character were found among diameter classes of beech and hornbeam also. Silt and clay were significantly greater under hornbeam than under beech. Moisture was significantly higher under beech than under hornbeam, whereas soil depths and diameter classes did not show any significant difference. Current research has shown that the influence of individual trees with different diameter classes can be detected in forest floors and upper minerals soil layers even under mixed stands in steepy sloping landscapes. This subject should be considered in natural forests management.

We conducted a study to examine the pattern of development of herbaceous plant species, woody species regeneration and soil physical characteristics after tree uprooting in 20-ha areas of Experimental Forest Station of Tarbiat Modares University located in a temperate forest of Mazandaran province in the north of Iran. Soil bulk density, soil texture and moisture from pit and mound (PM) were measured in the laboratory. Results show that the soil bulk density was most in soil deeper layers at mound top, and the soil moisture content was most in soil deeper layers at Pit bottom. Our study supports that the micro-topography of PM (pit and mound) topography 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. It is recommend that the fallen trees with PM structure should remain in the protected area without clearing as the best option for forest restoration. This information can be useful for forest management that attempts to emulate natural processes.

This study proposes a method for estimation of the size and monetary value of logging damage in forest stands and on regeneration. In order to perform economic assessment of damage on regeneration and stands as a whole, each damage factor was taken into consideration and its estimated impact was converted into a coefficient. The economic damage resulting from harvesting and timber extraction was estimated with the aid of mathematical models which converted quantitative into qualitative data. In a case study from northern Iran, felling and bucking resulted in 3.2% of the regeneration being damaged, and 0.16% could have been prevented. Furthermore, with winching and skidding operations another 4.8% of regeneration was damaged, out of which 0.38% could have been prevented. The total value of preventable damage on regeneration was US $5.14 ha−1 for each logging operation. The damage from felling and bucking operations amounted to 13.6% of residual trees in the stand, which was equivalent to $151 ha−1...

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.

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.

Gheibi F, Akbarinia M, Kooch Y. 2015. Effect of Alnus subcordata, Acer insigne and Sequoia sempervirens plantations on plant diversity in Hyrcanian forest of Iran. Biodiversitas 16: 10-15. Forest plantation is a common action in order to restore thedegraded forests in Hyrcanian forests of Iran. This study compares the plant biodiversity in four 25-year-old stands of plantation,adjacent understorey of alder (Alnus subcordata C. A. Mey.), maple (Acer insigne Boiss.), sequoia or red wood (Sequoia sempervirens(D. Don) Endl.) and mixed stand (maple and sequoia), located in Salmanshahr of Mazandaran Province, northern Iran. Research carriedout in, 10 sample plots with 20m × 20m area which taken by systematic-random in each plantation. All understorey species wereidentified, recorded and then the biodiversity indices (diversity, richness and evenness) were calculated. Our findings show that theplanted species had significant effects on understorey diversity. Statistical comparisons revealed that the highest and lowest diversity(Simpson and Shanon-Winer) and richness (Margalef and Menhinic) indices occurred in sequoia and alder stands, respectively. Theevenness indices (Camargo and Smith-Wilson) were significantly greater in maple, sequoia and mixed stands compared with the aldertype. As a conclusion, floristic change trends were different according to the planted tree species. A good understanding of thecomplexity of vegetation processes requires long-term monitoring of vegetation change.

Earthworms comprise a major proportion of the total invertebrate biomass in terrestrial ecosystems and they are often called "ecosystem engineers". Felling of trees by wind occurs continually in forest ecosystems. Many of trees are uprooted by windthrow, annually. The uprooting of old trees creates multiple microsites (e. g. pit and mound landscape) that are main source for soil heterogeneity. Efforts have been made in this study to determine the impact of pit and mound landscape on earthworm assemblages. Due to, the experimental forest station of Tarbiat Modares University studied that is located in Mazandaran province, northern Iran. For this purpose, twenty hectare areas considered and numbers of thirty four uprooted trees were found. Five microsites were distinguished including mound top, mound wall, pit bottom, pit wall and closed canopy. Soil samples were taken at 0~15 cm, 15~30 cm and 30~45 cm depths from all microsites using core soil sampler with 81 cm 2 cross section. Soil pH, water content, organic carbon, total nitrogen and carbon to nitrogen ratio measured in the laboratory. The earthworms were collected simultaneously with the soil sampling by hand sorting method. As a result, in this study soil characters changes had significantly impact on earthworm abundance at local scales. Earthworm's (epigeic, anecic and endogeic) density and biomass had more amounts in pit bottom whereas, no earthworms found in mound top and wall microsites. Principle Component Analysis (PCA) performed on earthworm population and environmental variables showed that water content and C/N ratio are potential indicators of earthworm abundance change.

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.

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.

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.