جستجوی مقالات مرتبط با کلیدواژه « گونه ی مرتعی » در نشریات گروه « آبخیزداری، بیابان، محیط زیست، مرتع »

The rangeland ecosystems of arid and semi-arid regions play the most important role in the distribution and density of vegetation in these areas due to the specific environmental conditions governing the soil, which is the bridge between living and non-living parts of ecosystems. Soil enzymes play important biochemical roles in the decomposition of organic matter at all stages in the soil system. These enzymes play an important role in the stability of the soil structure, the decomposition and formation of organic matter, the cycle of elements and the activity of soil microorganisms. Environmental stresses, such as drought, have negative impact on plant growth and soil microorganism's activity. Therefore, evaluating the effect of flood spreading on soil quality indicators can be a useful step in improving knowledge in this field. Therefore, this research was conducted during 2018 and 2019 to investigate the effect of flood spreading, plant types and characteristics on biological soil in the Kowsar floodplains located in Gareh-Bygone, Fasa.

Sampling of the soil around the roots of Artemisia sieberi Besser, Dendrostellera lessertii (Wikstr) Van Tiegh. and Heliantemum lippii (L) Pers, in two situations: with flood spreading and without flood spreading (control area) in spring and autumn from a depth of 0-20 cm and in three repetitions. After ensuring the normality and homogeneity of the variance of the data by the Shapiro–Wilk and Levene tests, the data were analyzed using the two-way variance method and mean comparison were made using Duncan's test at the 1% and 5% level and using the R software.

The results of soil fertility characteristics showed that there was no significant difference in the amount of phosphorus and potassium in the three pasture species studied under flood spreading and the control areas. However, the amount of carbon and nitrogen in all studied species was significantly higher in the flood spreading area (containing 0.3% organic matter) than the control area (with 0.15% organic matter). In addition, the results of this research indicated that the highest activity of acid phosphatase enzyme was observed in the rhizosphere of D. lessertii species and in the spring season, and on the contrary the lowest activity was observed in the rhizosphere of H. lippii species under the flood spreading condition. Alkaline phosphatase activity in all species was significantly higher in spring than in autumn season. The highest activity of this enzyme was observed for A. sieberi in the spring season with an average of 186 (µg p-nitrophenol g-1 soil h-1) in the flood spreading area and the lowest level was observed for H. lippii in the control area with an average of 57 (µg p-nitrophenol g-1 soil h-1) in the autumn season. In general, the level of phosphatase enzyme activity for the A. sieberi species in the spring season was approximately 89% higher in the flood spreading area than in the control area. The dehydrogenase enzyme activity was higher in spring than in autumn. Also, the highest activity of this enzyme was observed in the spring season for the D. lessertii  species with an average of 8.5 (µg TPFg-1 soil 24 h-1 ) in the control area, and the lowest level was observed in the autumn season for the A. sieberi species in the flood spreading area with an average amount of triphenol formazan was 1 (µg TPFg-1 soil 24 h-1 ) .In other words, the amount of dehydrogenase enzyme activity in the spring season was approximately 66% higher than that in the fall season in both areas (control and flood spreading). The results of this research showed that the activity of urease enzyme under flood spreading conditions in both seasons (autumn and spring), with an average of 270 and 300 (µg N/g.dm.2h) is more than the control area with an average of 173 and 250 (µg N/g.dm.2h). Also, the soil quality indices in all three studied species in the two (control and flood spreading) areas have a significant difference, so that the flood spreading operation has upgraded the value of these indices for the H. lippii species and the A. sieberi, while which has reduced the soil quality index of D. lessertii.

The results of this research showed that the flood spreading system is a desirable method for improving soil organic carbon, and its efficiency increases with the plant planting. The increase in moisture and the amount of organic matter in the flood spreading area can be a reason for increasing the activity of enzymes in the flood spreading area, so that in both autumn and spring, the activity of soil enzymes is more in the region. Considering the important role of organic matter in improving biological indicators and soil quality and health, the restoration of floodplains with native species can play an important role in providing these conditions. In addition, it is recommended that these tests be repeated with more samples and in different areas and the nitrogen, carbon, sulfur and phosphorus cycles and its relationship with the activity of other soil enzymes related to this cycle should be investigated.

Heavy metals are major soil pollutants due to their toxicity and persistence. Mining activities are a significant source of pollution in natural ecosystems. With its numerous mines, the Khaf region is a case in point. Identifying plants capable of absorbing metals from contaminated soils is crucial for phytoremediation efforts. This study investigated the phytoremediation potential of three plant species – Artemisia sieberi, Salsola richteri, and Scariola orientalis – in the iron mine area of Khaf city, Razavi Khorasan province, Iran.

All plant species were first surveyed at distances 500, 1000, and 3000 meters from the mine to determine the dominant vegetation type. Three species belonging to this dominant type were then selected for heavy metal analysis. Plant samples were collected from different parts (leaves, roots) of these dominant species, along with soil samples from around their roots, at varying distances from the mine and in the direction of the prevailing wind. A total of 36 plant and 36 soil samples were analyzed for copper, iron, and lead using inductively coupled plasma (ICP) to determine metal contamination levels. Plant remediation potential was assessed using various phytoremediation indicators.

Significant differences in phytoremediation indicators were observed among the plant species. Salsola richteri exhibited the highest bioconcentration factors (BCF) for lead (1.38), iron (1.37), and copper (1.99), and the highest bioaccumulation coefficients (BAC) for lead (1.55), iron (1.72), and copper (1.95). This indicates Salsola richteri's strong ability to accumulate these metals.The highest lead soil pollution index (2.64) was found around Artemisia sieberi, signifying moderate lead pollution exceeding natural levels in this plant's habitat. The highest iron contamination was observed in the soil around Artemisia sieberi and Scariola orientalis.

Metal concentrations in shoots, roots, and soil were highest at 500 meters from the mine and decreased with increasing distance. Soil analysis revealed higher average concentrations of the studied elements compared to global soil values. Notably, high concentrations of copper (490 mg/kg), lead (343 mg/kg), and iron (49000 mg/kg) were observed.At 500 meters from the mine, Salsola richteri displayed BCF values of 1.4, 1.5, 1.45, and 1.02 for lead, iron, copper, and BAC values of 1.7, 1.8, 1.4, and 1.34, respectively. Based on these results, Salsola richteri shows promise as a suitable plant for decontaminating soils in the Khaf mine area.

Marl lands are very sensitive to erosion in arid and semi-arid regions and are one of the most important sources of sediment production. Research has shown that there is a relationship between the geological characteristics of marls and different forms of erosion. In some marl formations, rangeland plant species have grown and stabilized which causes erosion control and soil stability. In order to better understand the status of these ecosystems, this study was conducted to identify the established plant species on marl lands and investigate the relationship between vegetation and physical and chemical properties of marl soil in three types of surface, rill and gully erosion in Semirom region.

Semirom is one of the marl regions that was selected for the current study in the classification and determination of marl erodibility indices of Isfahan province. In order to evaluate the erosion condition in three forms of surface, rill and gully erosion, BLM (Bureau of Land Management) form was completed in the same marl units and areas without vegetation cover. In the next step, three soil samples were collected from 0-20 cm depth in three repetitions in marl units including three forms of erosion. Physical and chemical soil properties including texture, EC, N, P, K, SAR, OC, CEC, CaSO4, pH, T.N.V and CaCO3 were measured. For vegetation studies in the study area, after preparing the floristic list of plant species, vegetation characteristics including canopy cover percentage and density per plant species, as well as the percentage of gravel and litter were measured and recorded. The statistical analysis of the data was done as a completely random design using SAS software and the averages of soil properties were compared according to the Least Significant Difference (LSD). Correlation analysis between soil and vegetation characteristics was also done by R statistical software.

Results and Discussion:
The results showed that in terms of erodibility, Marl lands with vegetation cover, had a better condition than without vegetation. The soil in the gully erosion was in better conditions in terms of nitrogen, phosphorus and organic matter and had better vegetation than the other two types of erosion. The results of correlation between physical and chemical soil properties and vegetation showed that the canopy cover factor was 95% and 86% correlated with the percentage of gypsum and the percentage of sand, respectively. The dominant species which showed the most protection capacity against erosion in surface, Rill and Gully erosions were Astragallus cephalantus, Cousinia cylindracea and Elymus gentry with 34.2, 33.3 and 22.05 percent of the highest combination of density and canopy cover, respectively. In terms of growth form, in all three types of erosion, forbs had the highest percentage of density and canopy cover.

The results of current research could be considered as a novel achievement in order to prevent soil erosion through establish appropriate species in marl lands with similar climatic conditions.

Marl formations are one of the most important sources of sediment production in arid and semi-arid regions. Marl lands are highly susceptible to erosion, causing an increase in drinking water treatment costs, reducing the useful life of dams, and significantly decreasing the permeability of floodwater spreading areas.  Different forms of erosion have been shown to have a relationship with the geological characteristics of marls, as evidenced by research. The results of the study of the effect of the physical and chemical properties of marl sediments on erosion in Latshore-Pakdasht showed that the amount of Na+, SO4-2 and silt in the marl lands increased, while the percentage of clay decreased from surface to gully erosion. The form and intensity of water erosion are greatly influenced by changes in soil texture. Gully erosion can be developed by increasing the amount of sand compared to the finer particles of silt and clay. Despite the difficulty of vegetation establishment on marl lands, in some areas, surprisingly, a relatively dense cover of rangeland species can be observed, which can cause erosion control and soil stability. The results of the systematic survey of plant species and their protective role in the marl lands of Ilam, Yazd and Gilan provinces all indicate that rangeland species are one of the most effective and suitable methods to prevent soil erosion by creating a stable vegetation cover on marl formations. The relationship between the physical and chemical properties of the soil with vegetation characteristics including distribution, canopy cover and density is inevitable. In the marl lands of Borujen, the research revealed that vegetation type named Astragalus brachycalyx-Daphne mucronata-Cirsium bracteosum can be established in neutral marl lands, with medium CaCO3 content and minimal presence of Na+ and Cl-. On the other hand, the vegetation type named Astragalus susianus-Daphne mucronata-Amygdalus elaeagnifolia can be established in alkaline and calcareous marl lands with very high amounts of Cl- and can be effective in controlling water erosion in marl lands. Considering arid and desert climate and the occurrence of surface, rill and gully erosions in the marl lands of Kashan region, as well as the importance of protecting and controlling erosion in the marl formations of the region and the lack of detailed vegetation studies in this region, accurate identification of the vegetation of the marl lands and prioritizing native and resistant plant species is necessary for the rehabilitation management of vegetation and biological protection of soil in these areas. Therefore, the aim of the current research is to identify rangeland species and investigate their role in erosion control in the selected marl formations in Kashan. In addition, the physical and chemical soil parameters of marl lands and the vegetation characteristics of plant species in different types of erosion are investigated.

Kashan is one of the marl regions chosen for the current study on the classification and determination of marl erodibility indices in Isfahan province. Two vegetation types named Anabasis setifera-Artemisia sieberi-Salsola tomentosa and Pteropyrum aucheri-Pteropyrum olivieri-Artemisia sieberi have been identified in the selected Marl lands of Kashan. In order to evaluate the erosion condition in three erosion forms of surface, rill and gully, BLM (Bureau of Land Management) form was completed in the same marl units and control areas without vegetation cover. In the next step, three soil samples were collected from 0-20 cm depth in three repetitions in marl units including three forms of erosion. The physical and chemical soil properties including texture, EC, N, P, SAR, OC, CEC, CaSO4 and CaCO3 were measured. For vegetation studies in the study area, after preparing the floristic list of plant species, three 100 m transects were established in a random-systematic method. In each transect 10 plots of 2 m2 were placed and vegetation characteristics including canopy cover percentage and density per plant species, as well as the percentage of gravel and litter were measured and recorded. The statistical analysis of the data was done as a completely random design using SAS software, and the averages of soil properties were compared according to the Least Significant Difference (LSD). Correlation analysis between soil and vegetation characteristics was done by SPSS statistical software.

The results showed that in terms of erodibility, Marl lands with vegetation cover had a better condition than those without vegetation. Based on analysis of variance, the physical and chemical parameters of soil and vegetation characteristics in three types of erosion had significant differences at level of 1% and 5%. In gully erosion, the amount of N, P, SAR, OC, litter and canopy cover were in better conditions compared to other types of erosion. The results of correlation between soil properties and vegetation characteristics showed that the canopy cover had significant correlation with the percentage of sand (r=0.92) and a negative correlation with the amount of CaCO3 at (r=0.97). In terms of the type of dominant plant species, in surface erosion Ephedra strobilacea Bunge. with canopy cover of 1.71%, in rill erosion Anabaisis setifera Moq. with canopy cover of 1.24% and in gully erosion Artemisia sieberi Besser. with canopy cover of 12.3% were identified as the most suitable species for soil protection. In all three types of erosion, bushes had the highest percentage of density in terms of growth form. In surface erosion and gully erosion, shrubs occupied the highest percentage of canopy cover.  In gully erosion, due to better conditions of soil moisture and organic matter, bushes and shrubs were successful in competition with annual and herbaceous plants. They established well due to deep and extensive root system. The results of current research could be considered as a novel achievement in order to prevent soil erosion through establish appropriate species in marl lands with similar climatic conditions.

More than other biological and environmental factors, the water crisis reduces the production of plant ecosystems, especially in dry climates. For this reason, the evaluation and measurement of rain becomes more important, especially in arid and semi-arid regions where soil moisture is a limiting and effective factor on plant production (Sadeghi and Attard 2014). The proportion of precipitation which is converted to precipitation depends on three major parameters. It includes: plant characteristics, precipitation characteristics and evaporation conditions (Grits et al. 2010). The aim of the current research is the effect of the amount and intensity of precipitation and the percentage of the canopy density of the Calligonum comosum and Haloxylon persicum leaves in the climatic conditions of Birjand in the period (October 2018 to June 2019).

This research was conducted from October 2018 to June 2019 in Faculty of Agriculture and Natural Resources, University of Birjand. This area is located at 59' 63' 21 º East and 21' 43 º 32 North. The average annual rainfall of this area in the 50-year period was 170.8 mm (Derakhshan et al., 2014). In this research, the rate of canopy rainfall interception of H. persicum and C. comosum were measured. For this purpose, four replications with low to high crown cover density were selected. Taking into account the large and small diameter of the shrub, the percentage of the mass of the crown were measured. To collect rainwater under each species, tray-shaped containers with dimensions of 30 × 30 cm were used. Also, in order to calculate the effective area of the canopy of the species during autumn to spring, the surface of their canopy was photographed vertically. In order to analyze the data, correlation tests, analysis of variance and one-way analysis of variance (ANOVA) were used. All statistical tests were performed by SPSS software and graphs were drawn by Excel software.

comosum is a drought resistant species and it is spread in sandy hills in deserts. The results show that the highest amount of canopy rainfall interception belongs to spring season with the amount of 15.6 mm. Also, based on the Pearson correlation coefficient, there is a significant positive correlation between the amount of precipitation and the amount of rain at the level of 0.01 (R2=0.93). There is a significant positive correlation between the intensity of precipitation and the amount of interception at the level of 0.05 (R2=0.79) and there is a significant positive correlation between the intensity of precipitation and the percentage of interception at the level of 0.01 (R2=0.87). H. persicum has a high ability to absorb soil moisture due to its low osmotic potential. The results revealed that there is a significant positive correlation between the amount of precipitation and the amount of interception and the percentage of canopy mass with the amount of interception at the level of 0.05 (R=0.78 and R=0.71, respectively). Also, there is no significant relationship between the percentage of interception and any of the precipitation characteristics.

Conclusion and Suggestions :

 The highest amount of interception belongs to C. comosum with a value of 15.6 mm and the lowest amount of interception is related to the H. persicum with 1.2 mm. The highest percentage of H. persicum is in February with 46% and the lowest percentage is 10% in December (p ≤ 0.05). Due to the density of leaves, H. persicum is more suitable for preventing floods and soil erosion, since more water is absorbed by the canopy and less water reaches the ground.

Soil contamination by heavy metals is a significant environmental problem worldwide. Human activities, including mining, are a source of pollution to natural resources. In this study, the phytoremediation potential of rangeland species including, Artemisia sieberi Besser, Zygophyllum atriplicoides Fisch. and C.A. Mey for the absorption of heavy metals of Ni, Co, As, Cr and V was investigated around the bauxite crusher of the Jajarm alumina mine in the direction of the prevailing wind. Soil sampling was performed at the distances of 450-700, 800-1200, 1400-2000 and 2500-5000 meters from the center of the bauxite crusher, and the control site. For this purpose, the seeds were planted in pots with a 3:1:1 ratio of sand, fertilizer and soil. Two-months later, they were transferred to pots with soils sampled from target distances. After completing of a vegetative period, the phytoremediation potential of the species was performed a factorial experiment in a completely randomized block design with three replications in greenhouse conditions. Results indicated that As, Ni, Cr, and Co absorption in above/underground of A. sieberi tissues were higher than Z. atriplicoides. But V absorption in above/underground of Z. atriplicoides tissues were higher than that for A. sieberi and between the vanadium accumulation in the aerial and underground organs of the target species and distances a significant difference was observed at the level of 1%. The amount of heavy metals transfer factor for A. sieberi and Z. atriplicoides was more and less than one in turn. Therefore, in terms of the transfer factor, A. sieberi has a potential for phyto-extraction and Z. atriplicoides has a potential for phyto-stabilization. The results also showed that A. sieberi and Z. atriplicoides were recognized as hyper-accumulating of nickel and cobalt metals. These species can therefore be recommended for the ecological restoration of soils polluted by heavy metals, especially nickel and cobalt in similar regions.

Agropyron pectiniforme and Elymus hispidus var hispidus are important and palatable species in Mazandaran province rangelands. This study aimed to select top populations for forage production and use them in rangeland breeding and rehabilitation programs. Seeds of native populations of Agropyron pectiniforme and Elymus hispidus var. Hispidus was planted in reticulated plastic trays and operated after emergence for a short period. In early spring, in the area of Poshtkuh research station in the southeastern altitude of Sari, were planted on two lines (repetitions) with a length of 20 meters so that 40 plants of each accession were placed on the planting line. Their distance on planting rows was 0.50 m, and the distance between the lines was considered one meter. The experiment was conducted during the years 2011-2015. In the first and second year, no plant data were recorded because of plant establishment. Evaluation criteria for plant selection were plant height at the time of cluster emergence, canopy cover, survival rate, forage production and seed production. Different phenological stages including vegetative stage, flowering, seed formation and fall regrowth were recorded in 7-10 days. The obtained data were statistically analyzed in SPSS16 software. The results of combined analysis of variance of data related to the performance of the evaluated factors showed that there was a significant difference at the (p < /em><0.01) between the populations of the studied species in terms of forage production yield, longitudinal growth, canopy cover, survival percentage, seedling strength, and seed production. There was no significant difference between different years in terms of the studied factors. There is a difference between some populations of the studied species in terms of phenological stages and these populations; the phenological stages have a delay of about seven days. Therefore, to produce and strengthen forage vegetation, the seeds of these populations can be used in the mountain rangelands of Mazandaran province.

In this research, the preference value of rangeland species in Sahand rangelands of East Azarbayjan province was studied for four years (2007-2010). The preference index method was used for this purpose. After determining the amount of production and consumption of each species selected in the grazing season (June, July, August, and September) and calculating the share of each species in the forage production of the region and livestock feed, and calculating the preference index, the data analyzed in split-plot design based on the completely randomized design in SAS software. The results showed that the effect of the year in three species, the effect of the month in four species, and the interaction of year and four species at (p≤0.01) were significant on the preference index. The preference index is a very important factor in determining the preference value of plant species for livestock. The species of Festuca rubra, Tanacetum chiliophyllum, with an average preference index of 1.4 to 1.6 during four-year, has a relative preference and is a relatively benign species and was placed in the palatable class I. Tanacetum chiliophyllum, with the highest average preference index, was ranked first among all herbaceous species. The species of Bromus tomentellus, Festuca ovina, Alopecorus textilis with an average preference index of 0.7 to 1.2 were of moderate preference and were classified as moderate in palatability and classified in the palatability class II.  Astragalus aureus, with an average preference index of about 0.3, had a relative preference, and this species was almost non-chewed and ranked in the palatable class III. Overall, the results of this study showed that the preference value of Festuca rubra and Tanacetum chiliophyllum was more than the other species, and the sheep preferred the forbs, followed by grasses and shrubs for sheep grazing.