Journal of Range and Watershed Managment
Year:2010 | Volume:62 | Issue:4|Papers Count:14

Two separated experiments were performed to evaluate the optimum hydro and osmopriming treatments affecting A. elongatum seeds. Hydropriming was conducted using distilled water based on five hydration time levels including 6, 12, 18, 24 and 30 hours in a completely randomized block designs with three replications. Osmopriming with PEG (6000) in time levels of 12, 24, 48 and 72 hours with concentration of -8, -10, -12 and -14 bars were also used. The experimental design for osmopriming factorial completely randomized block designs with three replications. The results showed that seed priming treatment significantly affected all of germination properties while the treatment for 12 hours of hydropriming had the highest effect compared to other levels of hydropriming. Meanwhile, treatment of 18 hours showed no significant difference with 12 hours expected to the percentage of germination. Treatment by -12 bars with 24 hours osmopriming showed highest effect but no significantly difference by -10 and -14 bars in 24 hours were shown. Totally, the results showed that 12 hours and -12 bar with 24 hours were best treatments in hydropriming and osmopriming compared to control, respectively. Therefore those seed treatments suggested as best treatment which improve the seed germination characteristics in A. elongatum.

Information is required for understanding of river suspended sediment for design and construction of water recourses management projects. Due to the importance of suspended sediment load and insufficient hydrometric gauging stations, this research was conducted in Glinak hydrometric station of Taleghan Rood basin in order to compare the sediment delivery yield based on hydrologic methods. It is necessary to determine the best method in the condition of deficit continuous data for the estimating suspended sediment from hydrological methods and evaluation of the sampling method to find out the best fitting amount on suspended sediment load. The results of this research showed that change in the absolute error in the methods has a direct relation with the variability of suspended sediment data. Also in some approaches, systematic sampling method and in the others methods combined sampling strategy showed the most appropriate results. Meanwhile the accuracy of randomized sampling method was the highest. Among hydrological methods, the "FAO" and the "Mean load within discharge classes” methods by MAE of 2170.9 and 2179.6 respectively had the most suitable results of the estimated suspended sediment for Taleghan Roud. Providing at least two sampling of instantaneous suspended sediment per week to increase the accuracy and precision of hydrological methods was as another result of current research.

Gully erosion is important due to connection of upstream to downstream, sediment transport and pollution, destruction of roads, huge damages of cropland, natural resources and infrastructures. In this research, the gully distribution map (1:25000) has been extracted through interpretation of aerial photographs (1:40000), field studies and topographic maps. General characteristics of the study area indicate that most of area consists of sedimentary rocks including marl, sandstone and mudstone which are related to Aghajari, Bakhtiyari and quaternary formations. In addition most of the gullies were founded in arable lands with deep and medium cores texture of hillslope soils (or regolite) with high or low salinity. Due to location of gullies in quaternary formations and no variation of climatic condition, the changes of gully morphology (U&V cross section) were attributed to the ground factors. Depth of gullies in rangelands compared to dry farming is half which reveals that gullies in rangelands are generating less sediment and the major explanation for this difference might be addressed to more capability of dry farming to runoff generation than rangeland. Results of statistical analysis between soil samples of U and V shape gullies illustrate a significant difference between Cl-, pH, Na+, and SAR. This difference was observed in whole of the soil profile as well as surface and subsurface horizons. Moreover, the regional analyses between gully erosion intensity (Y); and soil attributes as well as morphology parameters(X) indicate that silt and sand content, Ca2+ ,Mg2+, Na+, gypsum and slope gradient, depth, length and width of gullies have signification correlation with gully erosion intensity. It is remarkably emphasized that gullies process and evolution are a function of several factors. However, land use changing from rangelands to dry farming causes to decrease the topography and terrestrial thresholds and consequently increases the intensity of gully erosion.

Choosing the type, age, structure and ratio of grazing livestock is a primary decision in rangeland management. To find out the relationship between plant composition with sheep and goat grazing time, two plant attributes of canopy cover and forage yield were estimated in this study.  On the other hand, grazing time of sheep and goat were determined using video recording method. The relation between plant composition (based on canopy cover and forage yield) as the independent variable in the field were regressed against the grazing time of sheep and goat (dependent variables). The results indicated no significant difference (P£0.05) between grazing time of sheep and rangeland plant composition (not only based on canopy cover but also forage yield). Therefore, we can conclude that sheep is selective because do not graze based on frequency of plants in the field. A significant relation (P£0.01) was also found between grazing time of goat and rangeland plant composition (not only based on canopy cover but also forage yield). Hence, we concluded that goat is not selective due to the fact that goats grazed plants in proportion to their forage yield and canopy cover in the field. So, the optimum grazing can be achieved by common grazing of goat and sheep owing to different grazing time of plant life-forms and plant species.

Range condition identified as range health and compares the present status with the final potential status of ranges. Evaluation of range condition on the basis of clement theory is routine in Iran.  Capability of current range condition methods therefore, is the subject of this research. Two sites were selected one in sub-steppe and another in steppe regions in Ferydon shahr and Maimeh respectively. Two regions are located in Isfahan province. Vegetation type of sub-steppe is Grass-Astragalus and steppe Artemisia herba Alba. Looking through soil and vegetation status of the study sites they were put into three condition classes, good, fair and poor as benchmark. Within each class three replicates of five transects were places across environmental changes gradient. Data were collected from 1*1.5m and 1*2m plots on sub-steppe and steppe sites respectively. Having 25 plots alongside of each replicates totally data were collected during 2003 to 2004. Seven methods were selected to be tested namely 4 factors, modified 4 factor, 6factors, modified 6factors, vegetation and soil, African and finally observation and estimate. Taken the instruction of each method into account, the average score of range condition and its status for the time period of the study were calculated. Accuracy and precision were criteria on that, basis ability of the method, to evaluate range condition, were assessed. Results show that 4 factors as well as modified 4 factors methods are the most suitable ones for sub-steppe regions. None of the tested methods were producing accurate and precise range condition results in steppe regions. Low performance of the methods could be related to their origin, ecological differences, usage of unsuitable indicators, neglecting the site potential and the role of management. This study suggests revision of the methods in light of local (or national) site conditions. New method should have an ecosystem base and be able to discriminate between site potential and managerial effects.

Peak flow estimation is very important and challenging issue in hydrologic and socio- planning. Flood distribution methods are reliable methods for estimating hydrological events, but their application requires computer programs. Two well known equations for estimating annual peak flood are Chow’s regression method and stochastic method. These methods are simplified distribution methods which have not already used in Iran. In this research assessment of accuracy of these methods on basis of comparing their estimation with the best fitted distributions results was considered. Then for optimization of these methods, we defined the best coefficients in 20, 25, 30, 35 and 40 years return period using the Solver tools. In this program a cell determines a target that would has the highest value, and the coefficients of methods were placed in the changeable cells. In this research the Mean Absolute Error (MAE) was the target cell and determination coefficients of the methods were calculated on basis of its reduction. The results showed that the methods don not have significant difference with the best fitted distribution and the determined coefficients have no affect in reduction of MAE in return periods higher than 100 year.

This study was performed to test the effects of ascorbic acid, gibberllic acid and salicylic acid effects on germination and seedling growth properties of A. sieberi. For this purpose a factorial completely randomized design including three concentrations of salicylic acid (100, 200 and 300 mg/l), three levels of gibberllic acid (125, 259 and 500 ppm) and three levels of ascorbic acid (100, 200 and 300 mg/l) with four replications was conducted. The properties of germination percentage, germination speed, radicle length, plumule length, seedling length and seed vigor were evaluated under different treatments effect. The results of ANOVA showed that salicylic acid with 200 mg/l has the highest effect on germination percentage while initial growth characteristics were affected mostly under gibberllic acid application compared to other treatments. Totally, using salicylic acid and gibberllic acid with together could be resulted in suitable results in terms of A. sieberi germination and initial growth properties.

Land degradation and desertification in arid and semi-arid regions occur due to natural factors and human influences such as overgrazing, improper landuse and exploitation of groundwater resource. Salinity criteria might be due to geological conditions of the area. Due to the litologic diversity and the presence of saline formations including diapers, Hablehrood Drainage Basin was chosen for studying the effect of geology on salinization of the area. The objective of this research is to study the salinity index with geologic origin which is effective in degradation of some parts of Hablehrood Drainage Basin. First, by overlaying slope, land use and geologic maps of the area, working unit map was prepared as homogenous map of the area. Then sampling was performed randomly and top soil at the depth of 0-10 cm was sampled in each working unit. Then, chemical analyses were performed on each sample in the laboratory. It resulted the salinity map of the area having six classes and the relationship between salinity and geologic formations and rocks was then determined. The results showed that the order of formation having salinity problem from high to low are as follow: Lower Red Formation, Upper Red Formation, Qom Formation and Kond Formation.

Haraz watershed located in the north of Iran has high landslide capacity. However, the available information on landslides in this watershed is still limited. The purpose of this research is landslide hazard mapping using certainty factor, information value and AHP models in GIS environment in a part of Haraz watershed. For landslide susceptibility mapping, at first, landslides distribution map and effective factors map were supplied by field study, and then prioritization of effective factors was carried out using AHP. The investigation indicates that lithology, distance from road, slope, distance from drainage network, land use, elevation and aspect are the main landslide controlling factors in the area. In the next stage, landslide hazard map was provided using these factors as well as certainty factor, AHP and information value models. Evaluation of these models showed that certainty factor, AHP and information value models have the highest accuracy for landslide hazard mapping, respectively.