فهرست مطالب سید محمد حجتی

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

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

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

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

The study of soil property variability over time in forest stands to determine the optimal age range for various management purposes is a research topic that has received limited attention in Iran. This research aimed to investigate the changes in soil carbon storage according to age in reforested stands of Acer velutinum in the Neka-Zalemroud forests. Three age groups were selected: 10-20, 20-30, and 30-40 years. Statistical analysis was conducted using 20 × 20 m sample plots and a systematic-random method with 50 × 50 m grid dimensions. Five soil samples (in the center and square of the sample plot) were taken from the surface soil (0-15 cm) in each age class studied. The results showed that among the physical characteristics, the highest soil moisture (37.33%) was found in the 30-40 year age group, and the highest bulk density  (2.17 grams per cubic centimeter) was found in the 10-20 year age group. Upon examining the chemical characteristics of the soil, it was found that apart from acidity and electrical conductivity, the rest of the characteristics had significant differences influenced by the age of the stand. The highest amounts of absorbable phosphorus (7.81 mg/kg), total nitrogen (0.35%), and organic carbon (6.1%) were found in the 30-40 year old stand, and the highest amount of absorbable potassium (638.91 mg/kg) was found in the 10-20 year old stand. The carbon sequestration study showed that the 30-40-year-old stand had the greatest ability among the stands, with 305.89 tons of carbon sequestered per hectare. Therefore, based on the optimal age of carbon storage (30-40 years) for reforested Acer velutinum, the results of this research can be prescribed for different management purposes.

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

Although the exploitation of mineral resources is very useful for the country, it has a negative impact on human and plant life with its destructive effects. These destructive effects appear as pollution in the soil, which can lead to the imbalance of ecosystems and ultimately endanger human health. In addition, economic development and the expansion of industrial areas, especially coal mining mines, cause heavy metal contamination of the soil to become more severe and cause the destruction of soil resources and the deterioration of ecosystems in different regions of the world. The present study was conducted to investigate the contamination of the two elements Pb and Zn in the surface soil of the Komarzd mining area in Mazandaran province (Iran) due to coal mining.

Komarzd mines in Mazandaran province are one of the largest and oldest coal-producing areas in the central Alborz coal field. Komarzd mines are located 48 km from the southern district of Qaemshahr and 25 km from Alasht. Four indices, including CF, mCF, RI, and Igeo were calculated for 110 samples from surface soil prepared at a depth of 5-15 cm. After separating the rubble, the collected soils were kept in closed plastic bags with a unique code, and a GPS device recorded their location. The samples prepared in a dry environment were transferred to the laboratory. The ICP-MS method at 75 microns was used to analyze and measure the concentration of heavy elements in the collected samples. According to the presence of different elements measured in the region's soil and the compounds in it, two metals Zn and Pb were selected for evaluation and analysis. Sampling was randomly selected based on saved points and drilling tunnels. PCA statistical test is a type of multivariate analysis widely used in sediment, water, and soil pollution studies. Varimax Rotation is one of the most common types of PCA tests to interpret the results and contamination components of the method. This statistical method can be calculated using R and SPSS softwares.

The results showed that the ordinary kriging model is the most suitable model to show the region's concentration distribution of the two metals, PB and Zn. Also, the statistical status of the elements showed that the lowest amount of Zn for the Igeo index is equal to -0.53 and the highest value for the CF index is equal to 0.72. The amount of Pb concentration measured based on Igeo, CF, mCF, and RI indices equals 0.08, 1.03, and 213 mg/kg, respectively (RI<CF<Igeo). The results of the CF and mCF showed that the region has a low or moderate pollution status in terms of the concentration of the two determining elements; in other words, the value of this factor for Zn is less than 1 (CF<1) and the amount for Pb is (3 > CF> 1). The Igeo index showed that Zn with a concentration lower than zero is not polluted, but Pb with a value (0< Igo <1) has a non-polluted to slightly polluted state. The RI also showed that the concentration of the two elements is less than 150 mg/kg, so this index is also in the low-risk category of contamination (RI ≤ 150). By evaluating the graphs obtained from the PCA analysis, it was found that the two elements Zn and Pb in the correlation analysis graph have a good correlation and distribution, and the changes in the two axes show 47.9% and 24%, respectively, for the Igeo. This indicates the presence of environmental factors in the distribution of this element in the environment. The CF also showed that their distribution in region three negatively correlated with environmental factors. Its value for the two axes is 32.5 and 21.9 %, respectively. The correlation of the Zn element is less than -0.5, but the Pb element is more than -0.5. In general, the value of this variable is 8 and 20, respectively, based on the diagram of two minimum and maximum values. The mCF and RI indices showed that environmental factors influence the distribution of the two elements PB and Zn, and among the two elements, the distribution of the Pb element in the mCF and RI, results of 32.8 and 34.4 has the most influence from the distribution of the drilling tunnel and had environmental factors and has a lower correlation than Zn. The effect percentage of these two elements is 32.8 and 23.2%, respectively, and the two elements Zn and Pb have a good correlation and distribution with environmental changes and human factors.

According to the measurements and the results of four indices, the area is uncontaminated or has low contamination in terms of the concentration of two elements, PB and Zn. Therefore, mineral tailings and coal exploitation do not significantly affect the distribution of the mentioned elements. To improve the research results, other indices can be used to determine the role of environmental factors. Also, considering the agricultural lands and water resources of Talar River, it is better to use other elements that directly affect human health and analyze the region's conditions in terms of environmental pollution to achieve better results and accuracy. One of the main disadvantages of measuring the sources of pollution is the many problems in laboratory work and the preparation of laboratory materials. Still, with this research, it is possible to determine the existing doubts in the field of soil pollution for residents and show the impact of mining on the spread of pollutants. A suggestion to improve this research is to consider elements other than Pb and Zn in different environments such as water sources; In general, for a more detailed investigation, other elements that play a role in human health should be investigated.

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

Obtaining information and identifying the changes and dynamics of forest ecosystems in different developmental stages is necessary for optimal management, restoration and improvement of forests. The aim of  This research  was to investigate the effect of different development stages of the stand on tree regeneration and understory species in the mixed hornbeam stand in spring and summer (due to the beginning of vegetative activities until the optimal vegetative stage of herbaceous plants) in the forestry plan of Gorgan Shasat-Kalate district two was done.

In order to investigate development stages, after forest surveying, three rectangular half-hectare sample plots with dimensions of 50 x 100 meter for each development stage based on the characteristics provided by Leibundgut and Korpel in the field of the structure pattern of development stages and phases in natural forests were used. In order to study and investigate the vegetation cover, five small sample plots (20x20 meters), one of them in the center and four other in the four corners. In each sample plot, the percentage of herbaceous species cover and the tree regeneration frequency were recorded. To investigate and compare diversity in different development stages, use the diversity indices of Simpson and Shannon-Wiener, and to calculate the richness, use the richness indices of Margalf and Manhinik, and for evenness, use the evenness indices of Smith-Wilson and Evenness in PAST and R software (package Adiv software and specieseve function( were used.

The results showed that the number of plant species in the degradation stage is more than the initial and optimal stages. Diversity indices of understory species and tree regeneration species showed that the diversity of Shannon and Simpson in the two seasons of spring and summer in the optimal stage was lower than the initial and degradation stages. Also, Smith-Wilson and Evenness indices had the highest values in both spring and summer in the optimal stage. The highest value of the Menhinic richness index of understory species was determined in the optimal stage in the spring season, while no significant difference was observed between the different stages in the summer season. The highest value of Margalef richness index of tree species regeneration in both seasons was also observed in the degradation stage.

Based on the results of the present research, it can be stated that different development stages have an effect on the diversity of herbaceous species and forest regeneration. Therefore, there are significant implications of sustainable management on the vegetation layer, which should be considered in future of forest management strategies.

This study was conducted to investigate the potential of copper (Cu) absorption and accumulation and the effects of its contamination on the growth and mineral nutrient content of Artemisia absinthium and Silybum marianum under greenhouse conditions. This was done under factorial experiment based on a completely randomized design and Copper sulfate (CuSO4.5H2O) solution was added to the pots with three replicates at 0 (control), 100 and 200 mg/kg and then seeds of two plant species were sown. Plant harvesting was done after two months when growth was completed and then plant growth characteristics and mineral elements (Ca, Mg, K, P, Fe, Zn, Mn, and Cu) were measured for roots and shoots. The results showed that there was no effect of copper sulfate stress on roots and shoots of A. absinthium while shoot biomass and root volume, area and length of S. marianum were significantly reduced. The Cu accumulation in roots of both plant species and in shoots of S. marianum significantly increased by increasing the copper sulfate in soil. The highest level of Cu accumulation was found in shoots and roots of S. marianum with 53.50 and 168.72 mg/kg dry matter, respectively. A transfer factor less than one for both plants indicated their ability to copper accumulation in the roots. Potassium content in the shoot of S. marianum was significantly greater than that in A. absinthium at treatment of 200 mg/kg. There was no effect of copper sulfate stress on the micronutrients content of A. absinthium while it caused a significant decrease in Mn and Zn in shoot and root of S. marianum, respectively, and a significant increase in Fe in the shoot of S. marianum.

The locals' health in mining sites can significantly benefit from the protection of water and soil resources. These heavy metal sources can negatively impact human health and the amount and quality of goods produced in the area. For this reason, the concentration of two elements, cadmium, and arsenic, in the Savad Kouh mining area of the province was calculated using three indices: pollution factor, degree of pollution or modified pollution factor, and accumulation of land. Fifty-three samples from the area, including 45 samples of agricultural topsoil and eight samples of riverside sediment, were collected to analyze the site. The samples prepared in a dry environment were brought into the lab and subjected to ICP-MS analysis using a 75-micron sample size. According to the pollution factor, cadmium and arsenic levels in agricultural soil have low pollution, which has a CF value of 1. Cadmium has a low pollution status, and arsenic with a CF = 6 has a low to medium status, according to the concentrations of elements in the riverside sediment. According to the modified pollution degree index (mCd), the region's agricultural soil and sediment have extremely low or low pollution levels. In other words, the mCd values for the two elements cadmium and arsenic are in the very low degree of pollution (0≤mCd≤1.5). According to the findings of the soil accumulation index for two elements, agricultural soil has a non-polluted or low-pollution status. In other words, the index value is between 0 and 1. The area falls into the low to medium pollution category in terms of two elements, according to the principal component analysis (PCA) results.

This study investigated the influence of land-use change on soil quality in the Alandan area of Sari, with five different types of land-uses, namely pure beech stand and destructed forest stand, ash plantation, pine plantation, and arable land. Soil samples were taken from a soil depth of 0-10cm, using six plots (20×20m) in each site, which were selected by random systematic sampling network (50×100 m). The different physical, chemical, and biological characteristics of soil were measured in the laboratory. To calculate the soil quality index, characteristics such as field capacity, bulk density, geometric mean diameter, calcium, magnesium, and phosphorus availability, total nitrogen, ammonium, nitrogen microbial biomass and urease, acid phosphatase, and invertase enzyme were selected as the minimum data set by principal component analysis. In this study, additive and weighted indices were used to evaluate soil quality. The results showed that the higher amount of both additive and weighted index of soil quality were observed in ash plantation (0.76, 0.25), and their lowest amount was found in pine plantation (0.58, 0.16) and arable land (0.54, 0.15), respectively. It should be noted that the weighted index of soil quality in ash plantations was significantly higher than in different pine plantations and arable land. Also, the results of this study confirm that rehabilitation of degraded forests using coniferous species, which has led to a decrease in soil quality, such as soil condition in agricultural land, is not recommended.

The investigation of chemical, physical and biological soil properties in developmental stages could be an appropriate approach in low-altitude forest management concerning these ecological services. Investigating the changes in soil properties during the developmental stages of the low-altitude forest is of great importance in improving the ecological services. This research aimed to investigate the effect of different developmental stages of the mixed hornbeam stands on some physical, chemical and biological properties of soil in two seasons, autumn and summer (with a time interval of one year) in series number two of forestry plan of Shastkalateh, Gorgan.

35 half-hectare rectangular sample plots with dimensions of 50 x 100 meters were considered to identify the different developmental stages after the field visit. In each of the samples, the type of tree species, shrubs and the diameter at breast height were measured. Finally, using Feldman et al. (2018) index, three developmental stages of initial, optimal, and decay were determined for all samples and three replicates were considered for each stage. In each of these nine main sample plots of half a hectare, five micro-samples of 20 x 20 meters were selected; one of them in the centre and four others in the corners, then soil samples were taken from a depth of 0-15 cm in each micro-sample at summer and autumn. A total of 270 soil samples were analyzed.

The results of this study showed that there is no significant difference in the physical properties of the soil including sand, clay, silt and bulk density in the different developmental stages in the two seasons autumn and summer. But in both seasons, the soil moisture in the optimal stage was significantly higher than in other stages. Examining the chemical and biological properties of the soil showed that electrical conductivity, organic carbon, and the ratio of carbon to nitrogen, ammonium, and nitrate of the soil had significant differences between different developmental stages in the autumn. In the summer, acidity, electrical conductivity, percentage of organic carbon, total nitrogen, and microbial biomass of carbon, ammonium, and nitrate had significant differences between different developmental stages. The results of principal component analysis using the studied variables showed that, in general, the first and second main components accounted for 39.16 and 15.11 percent of the total changes, respectively. The acidity, electrical conductivity, and percentage of organic carbon, ammonium and nitrate had a high correlation with the first axis. Soil moisture, ammonium and nitrate had a positive correlation with microbial carbon biomass. While the variables of acidity, electrical conductivity and percentage of organic carbon had a negative correlation with microbial carbon biomass. Ammonium and nitrate also had a negative correlation with acidity, and electrical conductivity and organic carbon percentage showed a positive correlation with soil moisture.

Based on the results of the present study, it can be stated that in the low-altitude forest of the mixed hornbeam stand, the development stages had a significant effect on the chemical and biological characteristics of the forest soil. Although in other studies the significant effect of developmental stages on the physical properties of the soil has been reported, in the present study, the developmental stages had no significant effect on the physical properties of the soil. The results of this research contain valuable information about the seasonal dynamics of the soil characteristics of the low-altitude Hyrcanian forests in different developmental stages, which shows the relationship between the forest stands and the changes in soil characteristics over time.

Mining activities lead to the degradation of rangeland ecosystem structures and functions. Coal mining in rangelands generates substantial quantities of waste dumps, which serve as the primary environmental pollutants in the area and its surrounding ecosystems. Vegetation restoration in these mining areas can help reduce soil pollution and contribute to the overall landscape restoration. The aim of this study was to assess the physical and chemical properties of abandoned coal wastes in the rangelands of Kiasar, Mazandaran province, Iran. This information can be utilized to promote vegetation restoration on coal mine wastes by identifying the factors that limit plant growth and establishment on such substrates.

This study was conducted at the Kiasar coal mine in Sari, Mazandaran province, Iran. The mine site was established in 1983. The area is located at an elevation of 1030 m above sea level, with an average rainfall of 520 mm and a mean temperature of 13.2°C. A total of 10 coal waste dumps were abandoned in the area over the last three decades. Six age classes were identified based on the time since abandonment of these waste dumps in the surrounding area of the mine site. The identification process involved the assistance of experienced engineers and local workers. The age classes were categorized as follows: 4-6, 8-12, 15-18, 19-21, 22-24, and 25-27 years since abandonment. The control site consisted of natural rangelands around the mine, which are currently used for livestock grazing. Waste and soil samples were collected using a random-systematic method from a depth of 0-20 cm. The samples were then placed in plastic bags for subsequent chemical analysis. The soil samples were air-dried at room temperature, and various parameters, including texture, moisture, pH, EC, OC, CaCO3, N, P, K, Cu, Fe, Cd, Ni, and Pb, were measured in the laboratory. Data were analyzed using one-way ANOVA, and means were compared using Duncan multiple tests.

The analysis of variance indicated that all measured parameters of soil and coal, except nitrogen and potassium, exhibited statistically significant differences among the coal wastes and the nearby rangelands. The coal wastes had lower percentages of silt, clay, moisture, and lime compared to those in the surrounding rangelands. However, these properties did not show significant differences among the various abandoned coal wastes. Most of the abandoned wastes were characterized as neutral or alkaline, with an electrical conductivity (EC) less than 1.5 dS/m. An exception was found in the waste that was abandoned 22-24 years ago, which exhibited acidic pH

In conclusion, our study revealed that moisture availability is a crucial limiting factor for plant growth on coal wastes. This limitation can be attributed to the sandy and sandy-loamy texture, unstable slope of coal dumps, and high porosity of the substrate. Moreover, coal waste undergoing erosion and leaching exhibited high electrical conductivity (EC) and low pH levels. The levels of organic matter and available phosphorus were found to be insufficient for supporting optimal plant growth. However, the concentrations of heavy metals remained within the normal range, even after a significant period since the abandonment of coal wastes. We recommend the implementation of remediation treatments in similar restoration projects to enhance plant growth and establishment.

In this study, machine learning based models (linear regression, k-nearest neighbor, support vector regression, random forest) were evaluated to estimate carbon sequestration and soil respiration in the forests of eastern Mazandaran province. After identifying the sampling points, in each plot, the diameter and height of the trees were measured and the above-ground biomass of the trees was calculated using allometric models of Hyrcanian forest. Soil samples were taken from 0-20 cm depth and soil respiration was measured by CO2-port. Soil respiration was estimated using bulk density, moisture content, texture, soil temperature, total nitrogen, available phosphorus and potassium, organic carbon and above-ground trees biomass. Soil carbon sequestration was estimated using soil temperature and moisture and above-ground tree biomass. Random forest model (RMSE = 10.47 and R2 = 0.82) and support vector machine (RMSE = 0.77 and R2 = 0.90) had the highest performance in estimating carbon sequestration and soil respiration, respectively. Soil moisture had the highest relative importance in estimating carbon sequestration (random forest model) and soil respiration (support vector machine model). According to the obtained results, it is possible to estimate the amount of carbon sequestration and soil respiration in the forest with appropriate accuracy by having the above-ground biomass of trees and basic soil characteristics.

Soils are one of the largest carbon stores in the biosphere with the highest carbon storage potential to mitigate the effects of climate change. The aim of this study was to investigate different land uses on carbon storage and other physical, chemical and biological characteristics of soil in Shahriar. For this purpose, rangelands including 26-year-old, 16-year-old and 11-year-old Atriplex and 18-year-old Haloxylon, and agricultural lands including rainfed and irrigated cultivation, as well as control lands were selected.

 Soil samples from the depths of 0-10, 10-20 and 20-40 cm were randomly and systematically collected and analyzed. After drying, the soil samples were first passed through a 2 mm sieve and then the percentage of stones and pebbles was determined. Next, soil texture (percentage of soil constituents) by hydrometric method, acidity of saturated soil extract by pH meter, electrical conductivity in saturated extract by EC meter, soil lime by calcimetric method, nitrogen by Kjeldahl method, phosphorus by spectrophotometric method, sodium and potassium were measured by film photometric method, soil organic carbon content was measured by Walkly-Black method, and apparent specific gravity was measured by the clod method. Microbial respiration of soil samples was measured through a closed bottle, carbon and nitrogen of microbial biomass by fumigation-extraction method and metabolic contribution by dividing the released carbon dioxide (mg of carbon per gram of soil per hour) by the microbial biomass of soil carbon (gram of carbon) per gram of soil) was calculated. The microbial contribution was obtained by dividing the two parameters of soil microbial carbon (mg carbon/g soil) by soil organic carbon (g carbon/g soil). One-way analysis of variance (ANOVA) was used to compare soil data among different land uses. . Duncan's test was used to test the difference at the one percent level (p<0.01). All statistical analyzes were performed using the statistical software package SPSS, 19.       

The results showed that the physical, chemical and biological characteristics of the soil were significantly different (p < 0.01) between different land uses, so that the highest amount of carbon storage was related to irrigation treatment of 1.38% and the lowest rate was related to the control treatment of 0.14%. Also, the lowest bulk density is related to irrigated treatment of 1.36 gr/cm3 and the highest amount of basal respiration is related to 18-year-old Haloxylon treatment of 0.73 mg CO2 g−1 day−1. and Also the highest amount of microbial biomass carbon related to irrigated treatment of 124.55 mg g-1 soil. In general, agricultural lands have more potential for carbon storage than other land uses studied in this area. Finally, it should be said that different land uses have a significant effect on the physical, chemical and biological properties of the soil, and play a significant role in the long-term carbon storage in the soil.                                             

This research showed that success in restoring desert areas by using these species depends on knowing the relationship between soil and vegetation. The physical, chemical and biological properties of the soil affect the carbon exchanges between air and soil. The type of vegetation and land use are factors affecting soil properties. This research shows that the most appropriate ways to store carbon in the soil are preventing desertification and deforestation, also preserve and restore vegetation cover.

Quantifying the structure of forest stands by quantifying their different components helps to better understand for the management of different components of the forest ecosystem. One of the most important reasons for the structure quantification is that the forest structure is related to the habitat of many plant species, the modeling and reconstruction of the forest based on its structural characteristics, and the forest structure is an important source of information for forest dynamics, aesthetics and wood production. Therefore, in this research, the structural characteristics of two stands managed by single-selection and shelterwood methods were compared with the control stand.

In order to conduct this study, three plots including plot No. 3 with single-selection method, plot No.  13 with shelterwood method and plot No. 10 (control plot) were selected in Alandan forests, Mazandaran province. To study the structural features of forest stands, circular sample plots with an area of ​​1000 m2 were used (21, 14 and 25 sample plots in (In the plots of single-selection, shelterwood and control plot, respectively and a total of 60 sample plots). The inventory was conducted in a systematic-randomly method with a grid size of 200 × 150 m. To investigate the regeneration condition, a 1 m2 micro-plot in the center of the sample plot and its four main directions were used. In order to investigate the soil properties, sampling was performed by a combined method at a depth of 0-10 cm in the center of the large sample plot and the four main directions. Percentage of soil texture (including sand, silt and clay), moisture content, bulk density, pH, EC, percentage of organic carbon, percentage of organic matter, percentage of lime, total nitrogen, absorbable phosphorus and absorbable potassium were measured in the laboratory.

The results showed that the average number of trees per hectare was 206, 209 and 358 in the single-selection, control and shelterwood plots, respectively; which had a volume of 428.22, 477.14 and 373.3 sylve, respectively. The average percentage of moisture, percentage of organic carbon and percentage of organic matter in the single-selection was 49.4%, 4.7% and 8.2%, respectively; while, in the control and shelterwood plots they were 44.12 and 43.24%; 3.4 and3.28%; and 5.9 and 5.66%, respectively. The bulk density was 1.72 g/cm3 in the shelterwood plot; while, its amount in single-selection and control masses plots 1.22 and g/cm3, respectively.

In general, the results of this study showed that the implementation of different silvicultural methods such as the shelterwood and selection methods have different effects on the structure, regeneration, and physical and chemical properties of the soil.

The present study was conducted for investigation the trend of soil carbon, total nitrogen and soil aggregate stability changes with increasing depth under different land uses in Alandan area–Sari. The soil samples were taken from soil depths 0-10, 10-20, 20-30, 30-40, 40-50 cm using coring (8 cm diameter) and auger method in each site systematic randomly (n=6). The soil texture, soil pH, the percentage of CaCO3, organic carbon, total nitrogen and geometric mean diameter (soil aggregate stability index) was measured in the laboratory. The result showed that, soil carbon and nitrogen were significantly (p<0.05) affected by soil depth and land use change. However, the geometric mean diameter was only affected by soil depth. The compared means showed that, the amount of carbon, nitrogen and soil aggregate stability index is significantly reduced with increasing soil depth. In the surface soil layers, the highest carbon (4.6%) and nitrogen (0.31%) were found in ash plantation and theirs lowest (2.5 % and 0.15% respectively) were observed in pine plantation. Also, soil organic carbon is significantly (p<0.05) increased with increasing geometric mean diameter.

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

The dynamics of nutrients and their return to the soil through the litter is one of the most important pathways of the nutrient cycle in forest ecosystems. The aim of this study was to evaluate the dynamics of nutrients in pure beech, pure hornbeam and beech-hornbeam stands in Darabkola educational-research forest of Sari. For this purpose, in each stand, 10 sample plots with 1000m2 area were randomly established and by measuring the diameter and height of the trees, descriptive statistics of the studied stands were calculated. Then, litter traps with dimensions of 50 × 50 cm to measure the amount of litter fall per unit area and litter bags with dimensions of 20 × 20 cm (with a pore of 2 mm) with 10 replicated were installed in the studied stands for 360 days and at intervals of 60, 120, 180, 240, 300 and 360 days, the concentrations of nitrogen, carbon, phosphorus and potassium in the litter of the bags were measured. According to the results, the highest rate of litter falls with 1817 kg/ha was related to November and December in beech stands. In addition, the highest input of the studied elements was related to the pure hornbeam stand. The resultas also indicatedthe dynamics of phosphorus, potassium and carbon elements in pure and mixed stands are decreasing with a slight increase at the end of the period and increasing in the case of nitrogen and decreasing at the end of the period. The dynamics of the elements in the mixed stand showed more fluctuation than the pure stands. Also, the results of this study showed that the 200th to 300th days after litter fall is an important time range in the fundamental changes in the dynamics of litter nutrients.

This research investigated some physical and chemical characteristics of soil as well as quantitative and qualitative characteristics of trees in three stands of pure beech, pure hornbeam and beech-hornbeam mixture. In each stand, 25 plots of 400 m2 were selected by systematic-random method. In each plot, quantitative and qualitative characteristics were recorded. Also, litter and soil samples (up to 10 cm depth) were collected from each stand. According to the results, maximum DBH (54.47 cm), total height (22.31 m), basal area per hectare (82.03 m2) and volume per hectare (991.43 m3) were observed in pure beech while having the lowest number per hectare (314 tree per hectare). The highest C and C/N ratio of litter in pure beech were 33.16% and 13.52, respectively. Also, the highest quantity of N in litter was determined in two species of pure hornbeam (3.22%) and mixed beech-hornbeam (3.06%). In terms of soil characteristics, pure hornbeam stand showed the highest amounts of soil reaction (7.09), N (0.33%) and soil N sequestration (5.49 tons per hectare) compared to the other stands. However, the highest amounts of C (2.63%), C/N ratio (10.27) and soil C sequestration (77.16 t / ha) were observed in pure beech. The results showed that pure beech stand in terms of quantitative and qualitative characteristics and pure hornbeam stand in terms of soil fertility are in a more favorable condition.

Identifying morphoanatomica, physiological and biochemical responses of plants exposed to heavy metals is important for the vegetation restoration on coal mine sites. In this study, the effects of lead (Pb) were assessed on the growth and mineral nutrient content of Artemisia absinthium and Silybum marianum. A factorial experiment based on a completely randomized design was conducted with three replicates in a glasshouse using Pb(NO3)2 at 0 (control), 300 and 600 mg/L as treatment. After two months of the growth period, plants were harvested and their growth characteristics and mineral elements were measured for roots and shoots. The results showed that there was no effect of Pb stress on roots and shoots of A. absinthium while root biomass and volume of S. marianum significantly reduced under Pb treatments. The Pb content in roots of both plant species and in shoots of S. marianum increased. The maximum level of Pb accumulation was found in shoots and roots of S. marianum with 14.73 and 57.16 mg/kg dry matter, respectively. The Pb translocation factor was less than one for both plant species. Fe content in the shoot of S. marianum significantly increased under Pb stress. Mn concentration in the shoot of S. marianum was significantly greater than that in A. absinthium. According to the presence of these plants on coal mine waste and their abilities to grow and accumulate Pb in high concentrations, they can be used for soil remediation in a similar situations or in Pb-contaminated soils.

Mining activities causes substantial damage to the environment worldwide. Abandoned mine wastes from mining activities limit the growth of plants due to unfavorable conditions and the concentration of a wide range of heavy metals. Identifying plant species growing on mine waste and assessing their seed germinations are important for vegetation restoration on mining areas. This study aimed at assessing the germination characteristics of Artemisia absinthium, Lepidium draba, and Silybum marianum naturally growing on coal mine wastes in Mazandaran province under different concentrations of copper (Cu), lead (Pb), and cadmium (Cd).

Seeds were collected from plants growing in coal wastes during 2 years. Completely randomized design was conducted with three replicates. Treatments were CuSO4 and Pb(NO3)2 at 0 (control), 50, 100, 200, and 300 mg/L, and Cd(NO3)2 at 0 (control), 5, 10, 20, and 30 mg/L. In each replicate 20 seeds were placed in a Petri dish containing a layer of filter paper. Then treatments were applied and Petri dishes were taken to a germinator under controlled temperature, moisture, and light. Germinated seeds were counted daily and then germination percentage, germination rate, allometric coefficient, seed vigor index, phytotoxicity percentage and seed tolerance index were calculated.

The results showed that increasing the concentration of lead, copper, and cadmium significantly affected the seed germination of studied plants. S. marianum had better germination percentage and rate in lead, and copper while germination of A. absinthium, L. draba, was better in cadmium, and copper, respectively. The greatest reduction in germination percentage was found for A. absinthium in 20, and 30 mg/L Cd. As the concentration of metals increased, significant reduction in germination percentage and rate for A. absinthium started in lower concentrations than the other species. Root and shoot length of all species significantly reduced even in low concentration of metals and S. marianum had greater root and shoot length under all treatments. Reduction in seed vigor index was greater under Cu than that in Pb and Cd. High tolerance index was found for L. draba in response to cadmium and for S. marianum under the stress of lead and copper. In all treatments increase in metal concentration significantly increased phytotoxicity index. Under Cu and Pb S. marianum showed least phytotoxicity index while the lowest phytotoxicity index was found for L. draba under Cd stress. Copper and cadmium in high concentration were more toxic for A. absinthium than that for the other two species. Under similar concentrations of copper and lead, all species showed reduced germination in copper stress. Cadmium in lower concentrations were tolerable for plants but generally it had the greatest inhibitory especially on A. absinthium.

Overall the responses were different regarding to the plant species, metal and concentrations. All three species were able to germinate at high concentrations of heavy metals. The presence of these species in coal wastes and their ability to germinate in high concentrations of heavy metals makes it possible to use these plants in future restoration and phytoremediation programs.

Drought stress is the most important factor in the growth of plants in arid and semi-arid regions and plays an important role in the establishment of plants in these ecosystems. Russian olive seedlings were planted in environmental plan in the form of Complete Randomized Block Design (RCBD) with four replications and treat mental plan in the form of factorial with 2 factors in the greenhouse. The test factors were Arbuscular mycorrhizal inoculum (Rhizophagus irregularis, Funneliformis mosseae and control without inoculation) and four drought stress intensity (25, 50, 75 and 100% of field capacity (FC)). Seedlings growth rate include height, collar diameter, number of leaves, number of branches, weight of aerial and underground organs was calculated by comparison of the growth rate at the beginning and end of the experimental period. With increasing drought stress intensity, vegetative traits such as height, collar diameter, number of branches and leaves, root dry weight and shoot dry weight of Russian olive seedlings were decreased significantly. With increasing drought stress to 50% of FC, the main root length of seedlings showed an increasing trend, indicating an increase in root length under dehydration. The highest and lowest dry weights of seedlings shoot were observed in treatments of F. mosseae and control, 36 g and 18 g, respectively. Fungal species of F. mosseae in all morphological traits except root dry weight provided more favorable conditions for the seedlings, as well as the F. mosseae, showed more abundance and better coexistence with Russian olive seedlings.

Reforestation operations, recovery and acceleration of the regeneration and rehabilitation process of deforested areas are important to reach the pioneering forest. The current research aimed to study the effect of native broad-leaved species, redwood (Sequoi sempervirens) species and natural forest in Sardabrood forest, located in Mazandaran Province. For this purpose, four hectares from each studied forest stands (i.e. natural forest, redwood, maple, maple-alder and alder) were considered. In each of the stands, 16 sample plots (20 m ×20 m area) were taken to study of species diversity, richness and evenness indices in the term of plant biodiversity. Based on our data, the species of Carex sylvatica L. -Oplismenus undulatifolius (Ard.) P. Beauv- Pteris cretica L.- Viola alba L. - Microstegium vimenium (Trin.)- Ruscus hyrcanus Woron.- Rubus persicus Bioss. were found in all of studied stands. The highest diversity of forest floor belonged to the natural forest, so that the highest values of Simpson (0.94) and Shannon-Wiener (3.17), Camargo (0.49) and Smith-Wilson (0.24) were found in the natural forest. The greater amounts of Margalef (7.34) and Menhinic (4.78) were allocated to the redwood plantation. In the present study, monoculture plantation has led to the reduction of biodiversity. It is recommended to managing the degraded ecosystems. While maintaining the long-term quality and sustainability of forested areas, the maintenance of natural stands is prioritized and the reforestation with non-native needle-leaved species should be considered as next priority.

Fraxinus excelsior L. is a forest species with versatile biological and medicinal activities that its extracts are used as a model for making new compounds in the treatment of various human diseases. In this study, in order to investigate how the biochemical characteristics of this forest species are affected by environmental conditions, four habitats of Perchink, Amreh, Alandan and Qarnsara with an altitude of 200 to 1400 meters, were selected in Tajan and Siahroud watersheds located in Mazandaran province. In each habitat, skin samples were taken from 3 trees (repeated) in summer. Ethanol extracts were obtained by maceration and were analyzed by GC/MS and the physical and chemical properties of the soil samples were measured. The most important compounds of extracts were included:  benzeneethanol (30.33-51.35%), d-allose (6.20-31.72%), scopoletin (14.65-26.83%), tyrosol acetate (5.37-9.06%), carvacrol (0-4.93%), homovanillyl alcohol (3.84- 6.53%) which increased with increasing altitude. Also, there was negative relationship between the identified compounds and soil nutrients. Among them, only polyphenol tyrosol acetate behaved differently from the other compounds in a way that showed a negative relationship with the altitude factor and a positive correlation with the amount of carbon and absorbable phosphorus in the soil. Also, the chemical composition of d-allose was not observed in Perchink habitat. These results were showed that the chemical properties of this tree skin are affected by habitat conditions, which caused increases the species' resistance to pathogens. As a result, considering that the amount of active ingredients in this species was higher at higher altitudes and the presence of these compounds increases the resistance to pathogens, it seems planting this species is more productive at higher altitudes to achieve multiple goals in afforestation.

There had been no study about the effect of the plantations’ age on the properties of forest soils and soil carbon sequestration. Therefore, the aim of this study was to investigate the effect of an alder plantation’s age on some soil properties and carbon sequestration. Three alder plantation stands (25, 30, and 35 years old) located in Parcels No. 6 and 7 in Shastkolateh forest were selected. In order to investigate the quantitative characteristics of trees, the diameter and height of all trees were recorded using the full inventory method. In each stand, 20 × 20 m sample plots were considered using a systematic random method with a 50 × 50 m grid. A soil sample was then taken at the depth of 0-15 cm in each plot using the core method. The result showed that the 35-year-old stand had the highest soil moisture (45.49%±2.44) and the lowest bulk density (1.36 g/cm2±0.02). The highest pH (7.59 ±0.01) and the lowest EC (0.71±0.02 dS/m) were observed in the 35-year-old stand. The highest and lowest percentages of total soil nitrogen as well as carbon sequestration were observed in the 35- and 25- year- old stands, respectively. The results of component analysis showed that the 35-year-old stand was different from the other two stands; hence, it can be stated that alder plantation stands will have a high capacity for carbon sequestration at this age.