katayoun haghverdi

Destruction of vegetation and land use change can have significant effects on the variability of soil characteristics. Based on this, the present research was conducted to study the change of land covers on the characteristics of the soil surface layer in Kohpar Nowshahr, Mazandaran province. For this purpose, different soil characteristics in land cover (Carpinus orientalis Miller.), Crataegus (Crataegus microphylla C. Koch.) and barberry (Berberis integerrima Bunge.), Rangeland with the dominance of Agropyrom longyaristatum species, Rangeland with The dominance of Cousinia commutate species, has been studied in Kohper research station. Therefore, three plots of one hectare (100 m x 100 m) were selected in each of the studied habitats. In each of the plots, 4 samples were taken from the surface layer of the soil (surface 30 cm x 30 cm, 10 cm depth) and a total of 12 soil samples from each of the studied habitats were taken to the laboratory for analysis. The results indicated the significant effects of different land uses on most physical, chemical and biological characteristics of soil; So that the highest values of the characteristics of soil stability, clay content, pH, nitrogen, phosphorus, calcium, potassium, magnesium, fine-root and corse-root biomass, fulvic and humic acids and earthworms, acarina, nematodes, protozoa, fungi and bacterial populations and microbial characteristics were observed in the soil of Carpinus, Crataegus and barberry vegetation.The results of this research confirm that land cover Carpinus, Crataegus and barberry vegetation can lead to the maintenance of soil quality indicators in the semi-arid mountainous regions of the north of the country.

Soil, as habitat substrate, helps to regulate important ecosystem processes, including nutrient absorption, organic matter decomposition. Water availability and the well-being of humanity are directly linked to soil functions. On the other hand, vegetation with different species and ages have significant effects on the status of the surface soil layer through the creation of diverse environmental conditions and the production of different organic substances. However, few studies have been conducted in relation to the effect of the age of afforestation and the type of vegetation on the soil status. Considering that a practical, complete and effective assessment of soil condition should be the result of simultaneous measurement of physical, chemical and biological indicators, hereupon, the present study aimed to investigate the effect of 20-year old poplar stand, 20-year old maple stand, 10-year old poplar stand, 10-year old maple stand and rangeland cover, in plot 3 of Delak-Khil series of wood and paper forests in Mazandaran province, on the organic layer properties and physical, chemical and biological (including microbial activities, enzyme activity, earthworm population and biomass, the number of soil nematodes and root biomass) properties of the surface soil layer.  

For this purpose, some parts of the study area were selected which are continuous with each other and have minimum height difference from the sea level, minimum change in percentage and direction of slope. Then, in order to take samples from the organic and surface layer of the soil, three one-hectare plots with distances of at least 600 meters were selected in each study habitats. From each of the one-hectare plots, 5 leaf litter samples and 5 soil samples (30 cm × 30 cm by 10 cm depth) were taken to the laboratory for analysis . In total, 15 litter samples and 15 soil samples were collected from each of the habitats under study. One part of the soil samples was passed through a 2 mm sieve after air-drying to perform physical and chemical tests, and the second part of the samples was kept at 4 °C for biological tests. One-way analysis of variance tests was used to compare the characteristics of organic layer and soil between the studied habitats. In the following, Duncan's test (P>0.05) was used to compare the average parameters that had significant differences among different habitats.

The results of this research showed that afforested stands with different ages and pasture cover had a significant effect on the characteristics of the organic and surface soil layers. The results indicated the improvement of most of the characteristics of the organic and surface soil layer in the afforested stands, especially the 20-year old afforestation compared to the rangeland cover. The organic matter produced in 20-year old afforestation, especially with poplar species, had a higher quality (high nitrogen and carbon content and low carbon-to-nitrogen ratio) compared to organic matter produced in 10-year old afforestation and pasture cover. Most of the physicochemical characteristics of the soil under 20-year old afforestation were in a better condition than the other studied habitats. Also, according to the results of this research, the highest values of biological characteristics such as microbial activity, enzyme activity, and the population of earthworms and nematodes were observed in the subsoil of 20-year old afforestation especially with poplar species. Based on the results obtained from the principal component analysis, the higher values of nitrogen, phosphorus, calcium, magnesium and potassium content of the organic layer led to the improvement of soil fertility characteristics, microbial activities, enzyme activity, earthworm population, the number of soil nematodes and root biomass, respectively, under poplar and maple plantation for 20 years, meanwhile, 10-year old plantation, especially with maple species, and rangeland with the production of organic materials with high carbon content and carbon to nitrogen ratio, resulted in the reduction of organic matter decomposition (greater thickness of organic layer), and consequently the reduction of the mentioned properties of the surface soil layer. 

According to the findings of this research, it can be concluded that plantation with poplar species, especially after 20 years, had a higher ability to improve the soil condition compared to maple, which can be considered by managers in future afforestation. Also, with the passage of time, the presence of tree covers (poplar and maple) had a higher priority than rangeland cover in improving the fertility status and suitable edaphological conditions of the soil.

Nowadays the effective role of organic matter has been proven in improving soil productivity. Regarding to sensitivity of sustainable organic matter component to different land use practices in addition to the organic matter, investigation of changes in its compound is important. Determining the evaluation of organic matter and amount of carbon stabilization in soil system, and their quality and quantity will be varied according to the type of land use.

Due to extensive land use in the north of Iran, present study focused on effect of these uses on the content of organic matter and its humic components. In this regard a study was carried out in five land use including: beech forest, Fraxinus plantation, black pine plantation, degraded forest and agriculture in Tajan watershed. Eight points were selected in each site and soil samples were taken at a 25 × 25 area to a depth of 15 cm.

Highest of organic matter (4.68 %), fulvic acid (668.750 mg/100 gr soil) and humic acid (976.620 mg/100 gr soil) were observed in agriculture land cover. Some soil physical, chemical and biological features were also measured. Whole of studied soil characters were significantly different among land covers, except silt content.

Though as for the results, highest contribution of organic compounds were observed in agriculture land, according to the PCA analysis, soil nutrition condition and microbial activity were more appropriate in forest stands. More quality of debris along the favorable environmental condition and presence of microbial activity can be attributed to a reduction in rate of accumulation of remains following the process of organic matter decomposition and mineralization in forest stands. The findings of this study suggest that protecting of natural forest is very important. In addition, in degraded areas of northern Iran, planting of Fraxinus excelsior species can be considered due to improvement of soil quality and health.

The purpose of this study was to investigate the composition and biodiversity of herbaceous cover and regeneration in natural forest (dominated by hornbeam-iron tree), plantations (pure and mixed alder and maple) and degraded forest areas (without tree cover) in the Kelarabad of Chalus. A total of 16 large sample plots (20 × 20 m2) to record the vegetative characteristics of the trees and 144 small sample plots (1 × 1 m2) to record the number of regenerated woody species, type and percentage of herbaceous species. The variety of indices were used to compare biodiversity. The highest percentage of herbaceous species belonged to the Brachypodim pinnatum L., while in the degraded area the percentage of Rubus caesius L. was dominant. Among the understory herbaceous plants, hemicryptophytes and cryptophytes were the most abundant biological form. Also, according to the results, the highest percentage of regeneration species was related to the dominant tree species in each forest stands, and among regeneration species, Phanerophytes were the most abundant biological form. Investigation of biodiversity indices in both herbaceous and regeneration layers indicates the negative effects of forest degradation as well as the positive role of natural forest in the study area. As a general conclusion, the present study demonstrates the protective role of temperate broadleaf mixed forest stands for the richness and diversity of herbaceous plant species and the sustainable regeneration and conservation of understory communities.

The study of the litter quality and soil enzymes activities are used as indicators for soil quality and soil health assessment. The aim of this research was to investigate the effect of different vegetation types of Vaz forest of Noor-Mazandaran Province (i.e. Fageto-Carpinetum, Fageto-Aceretum, Fageto-Quercetum and Fagetum) on litter quality and activity of some of the most important soil enzymes. For this, eight samples of litter and soil (0 to 15 cm) were collected within the forest types in growing season. The ANOVA of litter, soil physio-chemical and enzymes activities rate indicate a significant statistical difference among forest types. The highest amounts of litter thickness (15.15 cm) and C/N ratio (79.08) were allocated to the Fagetum type and the least amounts of litter thickness (8.09 cm) and C/N ratio (42.15) were found under Fageto-Carpinetum type. The results showed that the highest activity rate of urease (23.14 µg NH4+–N g−1 2 h−1), acid phosphatase (521.12 µg PNP g−1 h−1), arile sulfatase (129 µg PNP g−1 h−1) and invertase (210.37 µg Glucose g−1 3 h−1) were significantly observed under Fageto-Carpinetum forest type. Based on findings, the soil of Fageto-Carpinetum forest type has better quality compared to other studied types. The results of this research can be helpful for prioritizing of forest stands based on plant residual and soil quality.

Decrease in natural forests area in north of our country due to various factors has caused the importance of reclaimed forest in this area which is carried out with the aim of developing forest surface and wood production. Therefore, study the nature of plantations can play an important and effective role in creating forests with better quality and quantity in the future. The forest plantation stands can effect on different litter and soil indicators. Various researches showed different types of broadleaves and needleleaves trees that are widely used in forestry have very different characteristics in the quality of the soil organic inputs. However, the role of Fraxinus excelsior, Quercus castaneifolia, Picea Abies and Pinus nigra species on litter and soil characteristics from the perspective of the quality indices and labile organic matter fractions, have not been studied. The purpose of this research was to study the litter quality and labile organic matter fractions in the forested areas of the Hyrcanian region, which is affected by the effect of Fraxinus excelsior, Quercus castaneifolia, Picea Abies and Pinus nigra on the characteristics of organic and mineral layer of soil. For this purpose, 40-years-old afforestation stands including Fraxinus excelsior, Quercus castaneifolia, Picea Abies and Pinus nigra species were selected and 8 litter and soil (25×25×15cm) samples were collected under each of stands. Collected samples of litter and soil were transferred to the laboratory for analysis, and the physical, chemical and labile components of soil organic matter were investigated. of the most litter nitrogen content (1.37%) and the least of litter carbon content (40.51%), C/N ratio (33.10) and litter thickness (8.05%) were found under Fraxinus excelsior. Soil physical and chemical properties (except for bulk density, silt and clay contents) were significantly differencesbetween tree species. Results showed that the soil under Pinus nigra had the highest values of particulate organic C (4.52 g/kg) and dissolved organic C (125.36 mg/kg). Greater amounts of particulate organic N (0.36 g/kg) and dissolved organic N (28/66 mg/kg) were belonged to Fraxinus excelsior soil. Soil N mineralization was significantly higher under Fraxinus excelsior (39.97 mg/kg) and Quercus castaneifolia (35.40 mg/kg) than in Picea Abies (26.85 mg/kg) and Pinus nigra (19.53 mg/kg). The findings of this research are indicating that the characters related to C are enhanced by needle-leaved trees, while broad-leaved stands improved the features related to N content. Result showed broadleaved species increased soil fertility regarding to better quality of litter

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

Soil physical, chemical and biological properties can be considered as the most important features of soil quality indices related to land cover and also climate changes. Afforestation with native and non-native species were employed for rehabilitation of natural degraded lands. Usually due to the study of soil quality, some properties are regarded that are more sensitive to environmental changes. Soil biological and biochemical properties are the features that response to environmental changes and ecosystem management in the short term. Soil as the site bed is affected by selected species type. Regarding to species type and its effect on soil quality properties is as management algorithm that is due to quantity preserve and long term stability of afforested areas.
To aim studying the effect of different land covers (Robinia pseudoacacia, Fraxinus excelsior, Cupressus arizonica and Pinus elderica) on soil physical-chemical, microbiological and CO2 emission characters, the present research was regraded in the Chitgar park. Sampling was done from the organic (litter) and mineral (0-20cm) layers using of the randomly systematic method. Litter quality properties (carbon and nitrogen), soil bulk density, texture, water content, pH, organic carbon, total nitrogen, nitrate, ammonium, carbon microbial biomass, nitrogen microbial biomass, CO2 emission (and their fluxes in different temperature and moisture regime) measured in the laboratory.
Results is indicating the afforested stands had significantly different effects on the whole of the physical-chemical properties of soil and litter (except carbon content). According to our findings, the highest amount of CO2 emission (1 mg CO2 m-2 d-1), microbial biomass of carbon (510.31mg kg-1) and nitrogen (0.13 mg kg-1) were belong to Robinia pseudoacacia stand. In addition, the maximum of CO2 emission was occurred in field capacity moisture regime and higher temperature.
The change of degraded land covers, afforestation with needle leaved and broad leaved species, improved the fertility indices, especially biological indices of soil quality in the study area. The highest amount of microbial respiration, microbial biomass of carbon and nitrogen were found under afforested site with broadleaved species and the least amount were detected in bare land. The results are indicated that the land use change and destroying of ecosystem plant covers is due to a severe reduction of mentioned indices in Chitgar region. So, land use change is a treat for soil health and quality in study area that must be considered in management of degraded natural ecosystem

The aim of this research was the studying influence of endemic and exotic afforestation on biodiversity of plant species and woody regeneration in Qaemshahr Chai-Bagh district, located in Mazandaran Province. Due to, 2 hectare area were considered in afforested stands of Acer velutinum, Alnus subcordata, Cupressus sempervirens, Pinus nigra with control area. To doing this research, 15 sample plots with 20m × 20m area were taken in each plantation and also control area. We recorded type and individual of woody regeneration with covering percent all of herbal species in micro sample plots with 1m × 1m area. For biodiversity analyses; Simpson, Shannon Wieners, McIntosh diversity; Margalef, Mechanic's richness; Pit and Hill's evenness indices were employed. Analyses of variance whole studied indices (for plant species and also woody regeneration) were significantly different among afforested stands. About plant biodiversity, the control area showed the most values of Simpson, McIntosh, Margalef, Mechanic, Pit and Hill's indices whereas the maximum of Shannon Wiener was detected in Pinus nigra stand. But, about the woody regeneration the greater amounts were observed in Acer velutinum for all of biodiversity indices. According to these findings, it is recommended that broad-leaved has more priority compared to needle-leaved for afforestation due to biodiversity (especially woody regeneration) development and conservation. Planting of need-leaved species should be considered in especial condition and with especial purpose beside precision studies of region ecosystem.