mahdie mahmoodi; Ataollah Ebrahimi; Mohammad Hasan Jouri; pejman tahmasebi
Abstract
The evaluation of utilization of key species is cornerstone of decision-making in rangeland management. Measuring utilization is essential for regulating grazing intensity, grazing pressure and distribution of animals. utilization of two key grass species of Dactylis glomerata and Bromus tomentosus, ...
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The evaluation of utilization of key species is cornerstone of decision-making in rangeland management. Measuring utilization is essential for regulating grazing intensity, grazing pressure and distribution of animals. utilization of two key grass species of Dactylis glomerata and Bromus tomentosus, as two important rangeland species is determined using height-weight relationship. The research is done in two vegetative periods of prior to flowering and flowering stages in two region of grazing land and exclosure by 32 transects of 100-meter length. To do so, the height of species was measured and cut at 1-cm above soil surface and weighted freshly. The samples are clumped and moved to the laboratory and oven dried at 65°c after separating litter divisions Then, the whole individual plants were weighted and cut in 5-cm intervals and each part was re-weighted and recorded separately for each species. Height-weight relationships were analyzed by different regression models in SPSS v.18 software. Result shows that sigmoid model significantly illustrate the height-weight relationship of both species of Dactylis glomerata and Bromus tomentosus with R2=0.994 and 0.997 at prior to flowering stage in the exclouser respectively. Similarly, sigmoid model also elucidate the height-weight relationship of both species of Dactylis glomerata and Bromus tomentosus with R2=0.975 and 0.998 at the flowering stage in the exclouser, respectively. The sigmoid model also best fitted for depicting height-weight relationship of both species at prior to flowering stage in grazing land for both species with R2=0.996, too.
Javad Daeizadeh; MAHSHID souri; Ehsan Zandi Isfahan; javad motamedi
Abstract
Total Petroleum Hydrocarbons are toxic and persistent pollutants that are considered as fundamental threat to the ecosystem. Phytoremediation, the use of plants for remediation of contaminated soils, is an effective and affordable way to reduce soil pollution. In this study, the potential phytoremediation ...
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Total Petroleum Hydrocarbons are toxic and persistent pollutants that are considered as fundamental threat to the ecosystem. Phytoremediation, the use of plants for remediation of contaminated soils, is an effective and affordable way to reduce soil pollution. In this study, the potential phytoremediation of pasture plants i.e. Agropyron intermedium and Dactylisglomerata in soil contaminated with crude oil of different concentrations (20, 30, 40 and 50 percent) was scrutinized for 120 days under greenhouse condition. At the end of the study, changes in biological factors (shoot height, shoot dry weight and root dry weight) of each species and changes in petroleum hydrocarbons of soil were measured and results were analyzed using SPSS software. The process of decay kinetics curve of petroleum percent was used to calculate the time it takes for decomposition of petroleum hydrocarbons. Results showed that three main features of biological factors of both studied species in different treatments were significantly different compared to control group. Analysis of changes in petroleum hydrocarbons indicated that Agropyronintermedium reduced 79.81 percent of oil in the treatment of 20% and reduced 58.54 percent of oil in the treatment of 50%. Therefore, it has higher phytoremediation ability in comparison with Dactylisglomerata. The results of the analysis of petroleum in soil samples, fitted with zero-order kinetic model showed that the first order kinetic model is the best model for simulating the trend of changes of Petroleum hydrocarbon of the soil
ardavan ghorbani; ardeshir pour nematy; zohreh sadat ghasemi; aliakbar shokuhian
Abstract
The aim of this study was identifying the effects of environmental factors on the distribution ofDactylisglomerataand Thymus kotschyanusin rangelands of Khalkhal and Kosar counties in the southern part of Ardabil province. From 111 selected sites, random systematic sampling was done using five 1m2 plots ...
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The aim of this study was identifying the effects of environmental factors on the distribution ofDactylisglomerataand Thymus kotschyanusin rangelands of Khalkhal and Kosar counties in the southern part of Ardabil province. From 111 selected sites, random systematic sampling was done using five 1m2 plots along a 40 m transect. In all sites, land cover parameters including stone and gravel percentage, bare soil, litter, and density of selected species were recorded. Soil samples were taken from the 0 to 30 cm of soil surface of each transect. Soil parameters including pH, organic carbon, potassium, phosphorus, electrical conductivity, Sand, Clay, and Silt were measured. One way ANOVA was used to study the significance of relationship between the effective environmental factors on the presence and absence of the selected species.Duncan's test was used to compare the measured factors.To determine the importance of measured variables on the distribution of selected species and grouping of sampling sites, canonical discriminant analysis was used. Results showed that variables of elevation, slope, temperature, rainfall, stone, gravel, litter, electrical conductivity are significantly different when species exist in contrast to the time that it does not exist (p<0.01). D. glomerata is mostly distributed on north aspect, and on sloppy areas, and the areas with the high litter, clay and organic matter, and T. kotschyanus is mostly distributed on west aspect, and on the areas with the high amount of sand, stone and gravel, and silt that create a good condition for the growth of this species. According to the results of canonical discriminant analysis, two functions with 77.8 and 22.2% and they explained totally 100% of the variance of data, and generally 94/4% of grouped cases, were correctly classified. Overall, the results of canonical discriminant analysis show that electrical conductivity, litter, precipitation, temperature, elevation, potassium, silt and bare soil are the most important variables in the distribution of D. glomerata and T. kotschyanus. Considering these results, better decisions can be made about management, restoration, and reclamation of rangelands.
