مجله مرتع
سال هشتم شماره 3 (پیاپی 31، پاییز 1393)

This study aimed to evaluate the effects of various levels of drought stress on the growth of Agropyron podperae. A factorial experiment in the form of completely randomized design was used to evaluate the effects of four different levels of osmotic potentials resulted from PEG 6000 including 0, -3, -6 and -9 bar on the species seedling condition in hydroponic environment. Three genotypes of Agropyron podperae including Tehran (63), Shiraz (7.5) and Lorestan (11.4) and four water stress levels were used in this experiment. The root, shoot and seedling lengths, root to shoot rate, seedling dry weight, seedling fresh weight, dry to fresh weight rate, sprouting rate and seed health index of the species in the all treatments were measured. The results showed that increasing the drought stress levels resulted to increase the root to shoot rate, seedling dry weight and dry to fresh weight rate of the species, but other measured attributes were reduced significantly. The measured plant attributes changed considerably in the -9 bar treatment. In general, Arak (3755) genotype had better sprouting percentage under the drought condition in compare with the other studied genotypes. The results indicated that the drought stress had significant effects on the seedling length and seed health index of the species.

The aim of this study was to investigate the effects of some heavy metals concentration (Cu, Pb, Zn and Mn) in shoots of Artemisia aucheri and Artemisia sieberi in the surrounding rangelands of Darreh Zereshk copper mine. The study area was stratified based on the wind direction, sub-catchments, distance from mine and etc. into 10 relatively homogeneous sites, and 10 samples were then collected from each site randomly. After acid digestion of the collected samples, the metal concentrations were measured using ICP-OES instrument. The one way analysis of variance (ANOVA) was used to compare the metal concentrations in the studied sites. According to the results, the average concentrations of Cu, Pb, Zn and Mn in the area were 8.34, 5.96, 36.67 and 49.82 respectively. The heavy metals concentrations across the sites differ significantly. The results indicated that the observed metal concentrations in the area were in the normal range for plant species; however the Pb concentration was slightly higher than the normal range due to high transportation activities in the area and the effects of Yazd-Shiraz road.

Soil conservation projects are required in most parts of Iran due to the severe vegetation removal and accelerated soil erosion. Vegetation as a bio-engineering tool has been used for erosion and sediment control in many ecosystems around the world. Vetiver grass is a highly valuable bioengineering technique that offers various benefits to the ecosystems. This species can be used for soil erosion control in sensitive areas such as Loess of East Golestan province. This study aimed to study the effects of ecological factors on the survival of the species. The result of this study can be used as a guide to large-scale cultivation of Vetiver in the area. The effects of topographic factors (three elevation ranges, two slopes, and two different directions) on the survival and some vegetation characteristics of Vetiver cuttings were studied in the Kechik catchment. Factorial analysis of variance was used to evaluate the effects of altitude and direction on the species survival, and independent T test was also performed to study the effects of slop on the species characteristics. According to the results, topographic factors did not have any significant effects on survival of Vetiver grass in the Kechik catchment. The results indicated that the elevation ranges had significant effect on the mean of height, crown, and root length of Vetiver grass (p< 0.05), while other studied topographic factors did not have significant effects on the measured plant characteristics (p> 0.05).

This study aimed to evaluate the effects of topography, soil, and climatic factors on the distribution of Artemisia fragrans Willd. in southeast faced slopes of Sabalan located in Ardabil province. 151 range places with various six vegetation types were selected to collect the data. One m2 plot with 5 replications along a 40 meters transect with 10 meters intervals were established in each site, and the presence and absence, density, canopy cover and production of the species were recorded. Litter, stone and gravels, bare soil and total canopy cover percentage were also recorded in the plots. Soil samples were collected along the established transects and pH, electrical conductivity, clay, silt and sand percentage, potassium, phosphorous, organic materials and calcium carbonate of soil samples were determined in the lab. Elevation, slope, aspect, rainfall and temperature maps were produced and these data for the range places were extracted. Independent-samples T test, cluster analysis and discernment analysis were used to analyze the data. Results showed that the studied variables had different influence on Ar. fragrans distribution. According to cluster analysis results, Ar. fragrans prefer range places characterized by low elevation and rainfall, and high temperature. It prefers saline and alkaline soil with moderate to light texture. The soils with low amount of organic matter and phosphorus and high potassium and calcium carbonate contents are appropriate for the appropriate growth status of Ar. fragrans. According to the discriminant analysis, elevation, rainfall, temperature, slope, organic materials, clay and silt percent, stone and gravels, sand percent, soil phosphorus, potassium and calcium carbonate contents, pH, electrical conductivity, aspect and litter percent were key environmental variables influencing Ar. fragrans distribution in the study area, arranged in importance order. Result of this study can be used to identify the appropriate areas for cultivation of this species in rangeland improvement plans.

Semi-circular bunds are widely used as a water harvesting method to improve rangeland condition in arid and semi-arid areas. This study aimed to evaluate the effects of semi-circular bunds on the structural and functional status of Naron-E- Khash rangelands in Sistan & Baluchistan province. The length and width of all patches, inter-patch lengths were recorded along the 10 established 50 meters transects in treated and reference sites. Eleven soil surface indicators with three replications were measured in each patch and inter patch area to calculate the stability, infiltration and nutrient cycling of the studied sites. The functional indices of treated and control sites were compared using independent t test. The functionality of various patched were compared using analysis of variance and the Duncan's multiple range test. According to the results, all structural and functional indices in treated and control sites varied significantly (α= 5 %). The functionality of soil surface covered by Zygoghyllum atriplicoides were more appropriate than soils covered by Artemisia sieberi, area influenced by semi-circular and inter-patch area (bare soils). Although this study indicated that semi-circular bunds can improve the structural and functional status of rangelands, biological restoration with endemic shrub and woody species is also effective to improve rangeland condition.

The effects of management practices on the status of rangeland conditions can be assessed by soil surface and functional indicators of rangelands. This study aimed to investigate the effects of enclosure on ecological index of rangeland health in Jbalbarez enclosure (Jiroft) using landscape function analysis. A control site (grazed site) next to enclosure was also selected to evaluate the effects of enclosure on the soil and vegetation characteristics of the area. Three transects of 50 meters length were established in each site. Eleven soil surface indicators were assessed to recognize three functionality indices including stability, infiltration and nutrient cycling. The results showed that the average ecological patches length (0.73m) was less than the control (0.87m). The results indicated that the average inter-patches length of control site was approximately 1.5 times more than the enclosure site. Organization index was also higher in enclosure site (1) compared to the control (0.39). The comparison of functional properties in patches and inter-patches in both areas showed that the patches had more contribute to the functionality of the sites in compare to the inter-patch zones. Although the stability (54.87), infiltration (29) and nutrient cycling (17.40) indices in the enclosure area were more than the control site, no significant differences were observed between the two areas (p‹ 0.05). Regression model analyses suggested that soil surface roughness, stability of natural soil fragments to the rapid wetting and perennial vegetation cover had more influence in the functionality indices of enclosure site. Perennial vegetation cover, resistance to disturbance and crust brokness had more influence in the functionality indices of the control site. This study indicated that the enclosure can enhance the functionality of the rangeland ecosystems considerably.

Evaluating the ecological capability and determining the natural capacity as well as appropriate planning and management actions ensure the sustainable utilization of the ecosystems. The aim of this study was to assess the ecotourism potential of the middle Taleghan located in the Alborz province. According to the importance of the ecotourism potential criteria, two groups of highly important factors (distance from attractive places, accessibility and path and topography) and less important factors (vegetation, soil erosion, distance from water resources and temperature) were determined. The spatial variables were classified, rated and overlaid for the whole studied area using geographic information system (GIS). According to the results, 3936/1 hectares (10/36%) classified as S1 class, 12309 hectares (32/42%) classified as S2 class, 14797/52 hectares (38/96%) classified as S3 class and 6934/5 hectares (18/26%) categorized in N classes. Results indicated that distance from attractive places, road and paths availability and vegetation in some vegetation types were the main limiting factors. Temperature, distance from water resources, topography and soil erosion were identified as the important factors to enhance the ecotourism capacity of the studied area.

The purpose of this research was to investigate the effects of different land uses on organic carbon distribution in soil size fractions. The sites with 18 years cultivated by Atriplex canescens with high, moderate and none (exclosure) grazing intensities were selected in Shahryar. The sites with 3 years after the cultivation of Atriplex canescens, barely field and control (natural non cultivated lands) were the other studied treatments. A systematic random sampling method was used to collect the soil samples from 0-10, 10-30 and 30-100 cm depths of soil surface with 3 replications. Soil samples were divided to five size fractions using different Sieves, and the carbon content of each fraction was then measured. Results showed that soil organic carbon contents were increased by reduction in fraction size in the all treatments. The highest amount of carbon contents were observed in F4 and F5 fractions. The carbon contents of fractions of 250µ were more than average soil carbon content, and in the fractions of 250 µ were less than soil average carbon content. Although the carbon contents of the studied treatments were different, but the ratio of fractions carbon content to total soil carbon content in the fractions did not varied significantly. This ratio for 1-2 mm fraction was decreased in the all treatments. This ratio for 250 µ fractions was increased in the barely field and 18 years cultivated by Atriplex canescens sites with high grazing history. The land management types that increase the carbon accumulation in the fine fractions can be considered as an effective step to sustainable soil carbon sequestration.