Journal of Range and Watershed Managment
Year:2011 | Volume:63 | Issue:4|Papers Count:10

Artemisia aucheri is a typical and dominant plant in semi-steppic rangelands of Iran.  In this study, the level and trend of changes in three essential minerals (phosphorus, potassium and calcium) were measured. These elements are the most effective factors in plant growth and have an important role in compliance of the animal needs. Sampling was done in three phonological stages (growth, flowering and seed production) and in three height level (2000, 2200, and 2400 m a.s.l.). The samples were analyzed in the laboratory and the amount of the elements was measured. Comparison of the obtained values was performed using statistical methods and the results indicated a significant decreasing trend in phosphorus and potassium content during the vegetative stages. However, amount of phosphorus and potassium changes with altitude showed no clear trend. Meanwhile, specific and significant changes in calcium content in different phonological and height levels were not observed.

Information on animal requirements for rangeland grazing capacity is essential. Therefore, animal unit equivalent (AUE) of each breed should be determined independently. In this research, live weight of Gharagol sheep based on average live weight of 3 and 4 years old ewes was determined. Then, two herds of Gharagol breed were selected. Within each herd, 15 three year old ewes, 15 four year old ewes, 5 three years old rams, 5 four year old rams, 10 three month old lambs and 10 six month old lambs have been selected. They were weighed two times including; at the time of end of grazing season in lowland and in winter. For determination of dry matter requirement, forage quality was taken in to consideration. According to the results; weight of Gharagol sheep (three and four years old ewe) was 53.53 ± 0.88 kg and weight of ram and lamb was 89.53±0.96 and 30.70±1.17 kg. Therefore, animal unit equivalent (AUE) for ewe, ram and lamb were 1.05, 1.55 and 0.69 respectively. According to MAFF equation (1984); daily metabolism energy requirement for maintenance condition of ewe, ram and lamb Gharagol sheep by considering condition of rangelands and distances from watering points and plant density was calculated 10.71, 15.81 and 9.15 Mj (including that multiplied by 1.5). Dry matter requirement based on forage quality for ewe, ram and lamb Gharagol sheep were calculated 1.50, 2.26 and 1.02 kg, respectively.

Knowing the number, area, and volume of landslides is important in order to determine landslide susceptibility and hazard to evaluate the long term evolution of landscapes dominated by mass wasting processes. Determining the volume of a landslide is a more difficult task that requires information on the surface and sub-surface geometry of the slope failure that, at present, can be achieved only by adopting empirical relationships to link the volume of individual landslides to geometrical measurements of the failures, chiefly landslide area. In this research, at first, the data of 442 landslides in Mazandaran province including area, volume and depth was provided. Then a new empirical relationship was calculated for prediction of landslide volume and this relationship was evaluated. Subsequently similar relationships in literature review were applied for the landslide observation data of Mazandaran province and were compared together. Results show that calculated volume values by new empirical relationship is in agreement with observed data (R2=0.823، Pvalue= 0.000) and some relationships which revealed applicability of presented relationship. Also for Mazandaran landslides, the relationships which were presented for large landslides in their study areas were more applicable than those presented for small landslides in their study areas. Regarding new relationship, the mean of landslide depth was determined 7.81 m that was close to mean of observed depth (7.38 m).

Results on evaluating habitats and forage quality of native range plants can be used for restoration of degraded rangelands and for determining proper time of livestock grazing. By doing field visits, natural habitats of three perennial grasses, Agropyron cristatum, Stipa arabica, and Stipa turkestanika were investigated in the rangelands of Northern Khorasan Province (NKP). Geographical distribution of each species was compared with the isoheights of average annual rainfall and temperature.  Main soil factors were studied in the selected habitats. Forage quality values were compared at the vegetative, flowering and seed ripening stages. The three grasses were found up to 1410 m.a.s.l, soil EC 0.96-1.2 mmohs, and slope degrees 0- >100%. Soil texture was loamy, with low salinity and weak alkaline condition, which contained low nitrogen, phosphorus and organic carbon. A. cristatum, S. turkestanika and S. arabica were respectively growing within the 8-12, <12, and 8oC; and their minimum rainfall was correspondingly limited by 240, 220 and 150 mm/yr. For the all species, crude protein was significantly higher than the critical level, during vegetative and flowering stage, whereas it reduced to the lower level during seeding stage. Metabolic energy was higher than critical stage, only during the vegetative growth. In conclusion, S. arabica had the highest tolerant to drought, A. cristatum had the highest palatability, as compared with the other two grasses. The proper time for grazing of all species is the flowering stage. However livestock also need to graze from other forage species, in order to compensate the deficiency of metabolic energy in their diet.

The study area is part of the north Gavkhouni Hole. This area is divided into smaller units named geomorphic facies because of variation in material, land cover, etc. The purpose of this study is to identify and separate the geomorphic facies of the study area. To achieve this goal, false color images obtained from the composite bands of red, green, and blue, six reflective bands of ETM sensor of Landsat 7, topographic maps 1:50000 and 1:25000, geological map 1:250000 and field observations were used. ArcGIS 9.2 and ENVI 4.4 were also used to process images and prepare thematic layers. In this research, operations related to remote sensing, including inserting of data, geometric correction and different methods of detection (making color combinations, enhancement of image, filtering and NDVI) were performed on satellite image of the study area. Then, the geomorphic facies were classified applying different methods. Visual interpretation method was selected as the best method for separating of the facies. In this method interpretation key was produced based on false color image (RGB: 741), then geomorphic map of study area was prepared. The results indicate the ability of RS and GIS techniques to identify units and produce geomorphic map. The map helps us to evaluate land suitability and environmental management of the study area.

Climatic factors and human activities can cause mass movements. Due to the risk of these movements to human communities, one has to control them. In order to control mass movements, different aspects of the movements should be studied in detail. The aim of this research is to evaluate the efficiency of a statistical model - logistic regression - and a probabilistic model - frequency ratio - in rockfall hazard mapping in the Salavatabad saddle in eastern Sanandaj, Iran. The study of 34 sensitive slopes and 34 stable slopes in the study area using field works, local interviews and the literature review showed that 8 factors including slope gradient, slope aspect, slope curvature, elevation above the sea, and distance from road, distance from faults, lithology and landuse are the most effective factors for occurring rockfalls. The relationships of rockfall and these 8 factors were studied by the logistic regression model and the probabilistic frequency ratio model and the generated rockfall susceptibility maps were compared. The results showed that both models work reasonably well for rockfall hazard studies; however, the logistic regression model has an accuracy of 85.09 percent of the Area under ROC Curve (AUC) in prediction of sensitive areas compared to the accuracy of 76.74 percent by the probabilistic frequency ratio model. Therefore, the logistic regression model can be used for rockfall hazard studies in the study area.

Determination of relative contributions of potential sediment sources is an important step in the development of management strategies in order to combat soil erosion. Many studies have attempted to quantify the sources of suspended sediment transported in river systems. A quantitative composite fingerprinting technique, incorporating both statistically multicomponent signatures and a multivariate sediment-mixing model, has been employed to determine the suspended sediment sources. This is done by comparing a selection of tracer properties of sediment, with the corresponding properties of the source materials within the catchment. In this study, the method has been applied at Abolfares Watershed, Khouzestan province. From 36 tracers, 10 tracers selected for distinct geology formations and 3 for landuse by statistical methods such as multivariate discriminate analysis and test of means comparison.  Then, portion of each source was determined by mixed models. The results have shown that Lahbari member of Aghajari formation, Aghajari, Quaternary, Gachsaran-Mishan, Ilam-Sarvak, and Pabdeh-Gourpi formations produces 29.3, 23.8, 19.3, 11.3, 9.3 and 6.9 percent of the watershed sediment yield, respectively. Also, agriculture and rangelands produces 56.3 and 43.7 percent of sediment, respectively. Low relative error, high model efficiency coefficient and field observations confirm the results. The fingerprinting approach to source ascription is appeared as providing valuable information regarding suspended sediment sources in the study catchments.

Rangeland’s ecosystems improvement through adapted exotic plants, in arid and semi-arid regions, needs deeply studies and investigations. Ecological positive or negative effects of exotic species must be studied before planting them in broad scale. This study was done for surveying probably effects of Atriplex canescens plantation on natural plant communities and soil of Abbas Abad area in Khorasan Razavi province. For this purpose, Atriplex species were planted and control areas were selected to be compared. In each area, five 50 meters randomized-systematic transects were placed. Measurements were done through point sampling method. Transects settled diagonal between Atriplex rows. Sampling data gained from Atriplex and control areas, then compared with t-test. Results shows there is no significant difference between Atriplex and control area both in species richness and diversity. But from qualitative view, Atriplex causes plant species to substitution so there is only 50 percent similarity between two areas. Soil samples data also compared through ANOVA and Fisher’s test. Results show significant difference in pH and EC between under the Atriplex shrubs soil, between shrubs row and control area. Atriplex caused soil to be more salty and alkaline.