فصلنامه تحقیقات مرتع و بیابان ایران
سال بیستم شماره 3 (پیاپی 52، پاییز 1392)

Information on animal requirements for rangeland grazing capacity is essential. Therefore, weight and animal unit equivalent (AUE) of each animal should be determined independently. In this research, live weight of Torki Ghasghaei breed sheep grazing on rangelands of Fars Province was determined. For this purpose, two herds of Torki breed were selected. In each herd, 15 three-year-old ewes, 15 four-year-old ewes, 5 three-year-old rams and 5 four-year-old rams were selected. They were weighted two times including; at the time of grazing season in lowland and highland rangelands. In addition, 10 three-month-old lambs and 10 six-month-old lambs were selected in highland rangelands. According to the results, theweight of Torki Ghasghaei breed sheep was 49.32 ± 0.69kg. Therefore, animal unit equivalent (AUE) for ewes, rams and lambs were 0.98, 1.55 and 0.48, respectively. According to MAFF equation, 1984, daily metabolism energy requirement for maintenance condition by considering condition of rangelands and distances from watering points and plant density in lowland and highland rangelands was calculatedto be 9.42 and 10.10Mj. Dry matter requirement based on forage quality in vegetation stage in lowland (1.77 Kg) and in flowering stage in highland (1.83 Kg) rangelands were similar. These results show that the time of grazing is effective on daily requirement and it is necessity to determine animal requirement based on forage quality.

To assess clay mineral compositions and the possible effect of floodwater spreading on the change of clay mineral types in the Gachsaran floodwater spreading station, samples were first selected from the control and floodwater spreading fields. Subsequent to sample preparation through X-ray, the clay minerals were determined carefully. According to the results, a number of clay minerals including Illite, Chlorite, Kaolinite and also swelling Smectite were identified in this area. Regarding all the samples, there were no significant differences in abundance of clay minerals, while some negligible differences were detected in the value of Illite and Smectite in relation to the control field samples; In fact, the amount of Illite and Smectitein of all samples were five percent more and lesser than that of control, respectively. In addition, at least 30 percent of the clays were Smectite. Therefore, after each flood in shallow sections and even in deep ones, Smectite clays swell immediately; that it can severely affect the soil permeability and subsequently a double effect on reducing water penetration. Such phenomenon can result in a number of remarkable problems in achieving the goals of floodwater spreading systems. Significant amounts of Illite clay showed that soils of the region under study were somewhat youth and in primary evolution. Although the possibility of structural changes of minerals in the floodwater spreading networks is theoretically expected to take place potentially, Gachsaran floodwater spreading station appears to have no significant effect on creating new clay minerals.

This research was conducted to produce the map of vegetation cover percentage of Sorkh Abad rangelands with an area of 21717 hectares by using IRS-Liss III data. Images of IRS-LissIII were geo-referenced by digital topographic maps with a scale of 1:25000. Due to mountainous condition, for obtaining the high accuracy at the geometric correction process, elevation corrections were done on the images. In this study, in addition to main bands, vegetation indices, ratios and principle component analysis also were used.For field data collection, systematic random sampling method was employed. In each vegetation type, one key area was selected. In each key area, four vertical and horizontal transects with 100m length were established. Then along the each transect vegetation cover percentage was estimated in ten plots of 1m2. In the next step, correlation between vegetation indices, ratios and the field data was calculated. Then the indices that had stronger correlation with field data were used for classification with higher accuracy. Among the vegetation indices, RVI (0/74%) and NDVI (0/704%) had shown the highest correlation. Based on the obtained results, we may generally conclude that IRS-LissIII images have a good capability for cover percentage mapping in the study area.

This experiment was carried out in order to study the effects of intercropping and mono-cropping of legumes and grasses on quantitative yield of forage. The study was conducted in a factorial experiment with three replications at Saral Research Station of Kurdistan province during five years (1999-2003). In this research, the effects of the cropping type including mono-cropping of Alfalfa, Bromus, and Agropyron as well as intercropping of Alfalfa+Bromus, and Alfalfa+Agropyron with three seed densities of 569, 853 and 1138 seeds were investigated. According to the results, the forage yield of the fourth and fifth years were affected by cropping type and showed significant differences at 1% level of probability. Results showed that mono-cropping of alfalfa with 2706 & 2199 kg per hectare, in the fourth and fifth years, respectively, showed superiority to other cropping types. In the second year of growth, seed density and the interaction effect between seed density and cropping type affected this trait and the highest yield (1049 Kg per hectare) was obtained in high density. Alfalfa, under mono-cropping and high seed density conditions, was superior to other species. The results of combined analysis showed that mono-cropping of Alfalfa with an average forage yield of 1744 Kg per hectare was superior to other cropping types and the highest yield was obtained in the fourth year of growth (1769 Kg per hectare).

Spatial distribution of livestock grazing is an important issue in range management as it affects land degradation. The reason of increased grazing pressure is not always the number of livestock. Inappropriate grazing distribution may also lead to such a pressure. Therefore, livestock movement by experienced shepherds who know the principal of pasture's system leads to optimum use of rangeland resources. Although, many factors may be important to define a grazing distribution, after reviewing the literatures, four factors including slope, water resources, quality of vegetation and aspect were selected as the main criteria to define the spatial distribution of livestock in this study. Spatial multi criteria evaluation (SMCE) method was used in a GIS environment to model the suitability of rangeland for grazing over the study area of Sefid-dasht range in Jashlobar basin, Semnan, Iran. For each selected factor, a GIS layer was prepared, and then, standardized in a Fuzzy scale, ranged between 0 and 1. The importance of each factor was calculated using the pairwise comparison method. The rangeland suitability for livestock grazing and movement was, then, calculated using a weighted linear combination (WLC) method. Comparing this map with the GPS records of livestock movement during the grazing season showed that the livestock movement was compatible with the suitability patterns resulted from this study. The results showed that the shepherds had the optimum use of rangeland resources. It was also concluded that the basin shape as well as the water resources were the constraints to use of rangeland resources by livestock.

Plant species are considered as one of the important biotic components of rangeland ecosystems, having close relationship with other components. Protection, rehabilitation and sustainable development of natural resources require further understanding of these relationships. The selection of plant species for mining area in arid regions is a suitable method for mine land reclamation and its surroundings to protect the natural environment. Chadormaloo Iron Ore Mine is located in a desert area of Bafgh city of Yaz province. Plant species were selected on the basis of plant adaptation to climate and soil conditions and different criteria were considered including regional perspective, disease and insect resistance, strength and growth, availability of plant species, economic efficiency, soil and water preservation, and prevention of pollutants. And then, scores were identified using fuzzy TOPSIS method through comparing the criteria and options with the aid of expert's verbal judgments. According to the results, Artemisia sieberi, halophytes, Salsola yazdiana, and Zygophyllum eurypterum showed maximum adaptation to current conditions.

So far, several methods have been presented in different parts of the world to estimate reference crop evapotranspiration. The most popular and prestigious of them can be combined methods of Penman family, modified Blany-Criddle, Hargreaves - Samani and thornthwaite. Due to the lack of Lysimeter data in the most regions of Iran, providing regional equations based on local conditions with the appropriate accuracy is very important. The main purpose of this research was developing a new regional model to estimate ET0. Firstly, the main variables affecting ET0 were identified using three approaches of artificial neural network (ANN), factor analysis (FA) and multiple-regression in four main synoptic stations (Yazd, Kerman, Isfahan and Shiraz) in central Iran. The results showed that the average monthly temperature was the most influencing factor on the amount of ET0. The regression equation between monthly average temperature (Tmean) and ET0 was extracted (ET0 = -0.0118 + 0.263 Tmean) for the entire study area. The result of obtained equation was compared with FAO Penman - Monteith, Blaney - Criddle, Hargreaves - Samani and Thornthwaite methods. The extracted equation was tested and evaluated by the data of four main stations and also Tabas, Fasa, Naein and Bam stations in Central Iran. The RMSE, MAE and R2 statistics were applied to compare the methods. The obtained equation was only depended on the mean monthly temperature and had very good accuracy to estimate the ET0 in comparison with Hargreaves-Samani, Thornthwaite, and even somewhere Blaney-Cridle methods in Central Iran.

Using satellite data is considered as one of the influential tools in the field of rangeland science. In this study, satellite data were used in order to prepare the map of canopy cover percentage Mouteh wildlife refuge in Isfahan province during 1972 and 2007. Vegetation indices were produced using MSS sensors for 1972, TM for 1987, TM for 1998 and image of LISS III sensor for 2008. To make correlation between canopy cover percentage and satellite data, 290 plot data with appropriate distribution across the region were collected by stratified random sampling method. By using data and prepared vegetation indices, canopy cover percentage was estimated for previous years and corrections between field sampling and vegetation indices were estimated. With regard to data analysis, SAVI index had the highest correlation equal to 0.78 with canopy cover percentage. Therefore, using the produced model from SAVI index, the map of canopy cover percentage was produced in four classes for each year and the changes of canopy cover percentage were detected using post classification change detection method. Results showed that during 1972 to 2008 canopy cover percentage decreased in this period so that low canopy cover areas (0-10%) increased from 40162 to 95597 hectares along with a reduction of 10-20% in canopy cover percentage.

Soil and water are considered as the most important blessings of God, having fundamental role in the creation or elimination of different civilizations historically, and today are the most important factors in economic growth and prosperity. Soil erosion is a natural process which is intensified by human activities. Soil fertility decline and the loss of organic matter including nitrogen, phosphorus and potassium are the result of erosion. Reduced forest cover, reduced crop production, increased floods, reduced electricity production, reduced quality of drinking water, sedimentation and so forth are on-site and off-site effects of soil erosion. Since soil erosion is one of the most important issues in the context of sustainable development and environmental issues and in the future is considered as one of the major challenges facing the world (particularly in the natural resources and agriculture sector), this research was conducted to estimate the economic losses of soil erosion in the rangelands of Lorestan watershed using NRCM. The total erosion in the area was estimated to be 107500.6 tons per year using MPSIAC. Economic losses of soil erosion in the study area was calculated for four major elements (N, P, K) using NRCM. The results showed that direct costs of soil erosion of the watershed were 603047733550 Rial.

Knowledge on the effects of environmental factors affecting the distribution of plant communities provides information about ecological characteristics of species as well as the conditions of vegetation habitat. The current study was performed in Halejerd, west of Tehran to investigate the effects of environmental factors on the distribution of plant sites. This research was aimed to identify the most effective factors on the establishment of plant sites. After identifying the region, vegetation types were selected and sampling was done by random-systematic method. Minimal area method was used to determine the plot size. Five vegetation types were identified. Three soil profiles were dug in each vegetation type and two soil samples were taken from two soil depths. Soil characteristics including soil texture, pH, electrical conductivity, potassium, nitrogen, phosphorus, organic matter, organic carbon and TNV were measured. Result showed that the studied plant sites differed in terms of soil characteristics and the factors of each component were characterized. According to the obtained graph and considering variable coefficients, the content of silt and potassium increased in the first component while in the second component the content of sand and nitrogen increased. Also, soil chemical and physical characteristics are involved in the separation of vegetation types. Important and effective physical and chemical characteristics were sand, silt, potassium and nitrogen, respectively. In order to analyze the environmental factors (soil characteristics) associated with the distribution of plant sites principal component analysis (PCA) was used. Results showed that there was a special relationship between the distribution of different vegetation types and soil characteristics. Also it was found that edaphic factors including soil texture, potassium and nitrogen were more effective in species distribution.

Water in arid and semi-arid regions is the most important ecological factor, determining the growth and development of plant species. Therefore, for optimal growth of plants, effective use of water resources should always be considered. In order to investigate the crop water requirement and water stress effects on Fortuynia bungei Boiss, a Completely Randomized Design (CRD) with three treatments and three replications was implemented in the Natural Resources and Agricultural Research Station of Yazd Province in 2011. The treatments included 100, 50 and 25% of soil moisture field capacity (FC). Results showed that water deficit significantly (p<0.01) affected evapotranspiration and Water Use Efficiency (WUE) of Fortuynia bungei. The evapotranspiration rates in 100, 50 and 25% of field capacity were 4.8, 3.7 and 2.3 mm, respectively. The crop coefficients in 100, 50 and 25% of field capacity were 0.666, 0.519 and 0.325, respectively. The lowest water use efficiency was in the treatment of 25% FC with 0.3 gr. dry weight per 1 liter of water. The highest water use efficiency was in the treatment of 50% FC with 0.53 gr. dry weight per 1 liter of water.

Plants are affected by different environmental stresses including drought stress. Drought causes plant osmotic imbalance and inhibits plant growth and productivity. Also, it induces reactive oxygen species that damage plant cells. Some plants are able to regulate the concentration of ions and metabolites and so they can tolerate drought stress. Enzymatic antioxidant plays important roles in eliminating reactive oxygen and inhibition of damages. This research was aimed to study the effect of drought stress on peroxidase enzyme activity in sainfoin (Onobrychis sativa l.). A factorial experiment was conducted in a randomized complete blocks design with four replicates and four levels of field capacity in percent as treatment. Results showed that peroxidase enzyme activity increased by increase of drought level in leave and stem and decreased under severe stress (25 percent field capacity) and in root the changes of enzyme activity was against and by increase of stress level, peroxidase enzyme activity decreased in plants and only in plants under severe stress increased. Qualitative consideration of peroxidase enzyme activity showed, by increase of drought level, the number of isoenzyme bands increased thus in leave and stem treatments under 50 percent field capacity and in root treatments under 25 percent field capacity showed most number of bands that it was according to quantitative peroxidase enzyme data. According to obtained results, peroxidase enzyme in sainfoin plant is one of the antioxidant components, affecting the drought tolerance of this species by eliminating free radicals.

The evaluation of the amount of water requirement for afforestation, range improvement and forage production particularly in arid regions is considered as one of the essential needs of the executive departments in the country. In this article, the water requirement for Haloxylon was determined in three desert areas of Iran (Ahwaz, Bandarabbas, Chahbahar) using Cropwat 8- FAO Penman-Mnteith method. For this purpose, climate data were obtained from the nearest station to the plantation areas of Haloxylon. Soil texture, depth of root zone and other properties were evaluated from soil profile analysis where plant species were investigated. The phenology of the species was prepared through the available references and studies. After collecting all required metrological data, effective precipitation was derived from USDA method. Reference evapotranspiration (ETo) of each station and the amount of effective precipitation were then calculated at study areas for each individual stations. Results showed that effective rainfall in desert areas had a small contribution to plant water requirements, thus supplementary irrigation is needed during the growth season. This study also showed that the highest water deficiency for Haloxylon was recorded in July, June and May. It is also concluded that the annual reference evapotranspiration and the amount of effective precipitation in Ahwaz, Bandarabbas, and Chahbahar were calculated to be 2044, 1825, 1642 mm; 108, 93 and 59 mm, respectively. The highest annual-water requirement estimated by Crop-wat for Haloxylon species in above three stations was calculated to be 211, 112 and 77 mm, respectively. It also showed that although the three regions were located in areas with similar climatic and vegetative regions, the amount of water needed for supplementary irrigation in Ahvaz was almost three times higher than that in Chabahar and two times higher than that in Bandar Abbass.

In order to evaluate the forage production stability of rangeland species in Gavanbane Harsin, the production per hectare was estimated for eight species in a completely randomized design with five replications during four years. Combined analysis of variance for dry forage production indicated significant differences among the years and species at 0. 01 level of probability. The results of mean comparisons, at 5% level of probability, showed that maximum forage production was obtained for Bromus tomentellus, Festuca ovina and Poa bulbosa, compared to other species. The interaction effect of species×year was significant at 1% level of probability and parametric and non parametric statistics were calculated on the basis of average forage production during four years. Parametric statistics including CVi, S2di and R2i and non parametric statistic including)Si)1)Si) 2، (Si) 2، Si)3، (Si) 6، (NPi) 3 and NPi had an identical trend in introducing stable species. Based on these statistics the most forage production stability was recored for Acantholimon olivieri, Eryngium thyrsoideum and Poa bulbosa. Parametric statistics of bi، Wi2 and δi2, and non parametric statistics of NPi (1) and NPi (2) also showed similar trend in the expression of species stability and the most production stability was obtained for Astragalus flexilipes and Scariola orientalis. Our results were confirmed by group classification of species stability using cluster analysis and principle component analysis for species ranking according to the statistics of stability. In general, Bromus tomentellus and Festuca ovina had a desirable forage production while their production stability was poor. In contrast, Scariolaorientalis and Astragalus flexilipes had desirable production stability while their forage production was poor compared to other species. Acantholimon olivier, Eryngium thyrsoideumand and Poa bulbosa had relatively moderate forage production and relatively favorable production stability. The low stability of the species having favorable forage production indicated that in addition to considering the amount of production, the stability of production also should be taken into consideration as an important factor, affecting the range condition. In terms of production, production stability, and palatability class, Festuca ovina and Poa bulbosa could be introduced for range improvement programs.

One of the most important indicators of rangeland health is the diversity of their vegetation which is affected by different factors. In this regard, the physiographic factors can be pointed out in which the altitude is considered the most important. The present study was carried out to assess the changes in vegetation at an altitudinal gradient over a period of three months in part of Hamedan rangelands. For this purpose, three height levels including low altitude (1800-1900 meters), medium altitude (2200-2300 meters) and high altitude (2600-2700 meters) were selected and sampling was conducted 5 times with a 21-days intervals. The diversity indices of Shannon-Weiner, Simpson diversity, Simpson and the evenness index of Pylo were calculated to compare the vegetation varying along altitudinal gradient at different times. The results revealed that most of the estimated indices were varying along altitudinal gradient and with changing of the seasons (P<0.05), as the highest diversity and the evenness were recorded in the second harvest and at mid- and high-altitude respectively. An interaction between altitude and the season was also observed with all of indices (P<0.05), as from spring to summer, species diversity was declined after an early increasing at low altitude, but at higher altitudes this variation was accompanied with a delay. Evenness was increased with the season but this trend was moderated along altitudinal gradient.

Rangelands are composed of a variety of plant species whose different phenological stages are largely influenced by climatic factors. Therefore, considering the fluctuations of climatic conditions, each species is ready to be grazed in a particular time of growth period and also grazing should be stopped in a particular time. In this research, the phenological stages of Stipa barbata were investigated in five sites of semi steppe and three sites of steppe vegetative regions during 2007-2010. After determining the geographical characteristics of each site, 10 plants were selected and the growth stages including germination, vegetative growth, flowering, seed maturity, and dormancy period were recorded in 15-day and 7-day periods during growth stage and reproductive stage, respectively during four years. Also, meteorological data including daily tempreture, and monthly rainfall were collected from the nearest synoptic station. According to the results, the phenological stages of the studied species were more affected by GDD and rainfall index during the growing season. GDD (Growth Degree Days) in each phenological stage was almost identical from year to year with little difference. It is also not much difference among the studied sites.

Each species has a specific production during the grazing season and different years. Also, the grazing livestock consumes certain forage which is different in terms of different conditions and breeds. Planning and management of rangeland and livestock is not possible without understanding the production characteristics of plants and forage consumption of a rangeland during the grazing period. This study was implemented during four years in Urmia-Gharebagh rangelands to evaluate the vegetative characteristics and forage production and consumption by livestock at different phenological stages. For this purpose, with the start of the grazing season and livestock entry to rangeland, the remaining forage of each species was harvested with one -month intervals until the departure of livestock grazing and the consumption rate was calculated by subtracting it from the production inside the exclosure. Finally, in order to study the effect of years and months on the production and consumption of species, data were analyzed. The results of combined analysis of variance showed that, in most species, the highest forage production and consumption were obtained in the fourth year along with the increment of rainfall in this year compared to other years. During the six months (April to September), the highest forage production and consumption was recorded in May in all years of study. The lowest forage production and consumption was recorded in September and April, respectively. The highest production and consumption were recorded for Festuca ovina, Helychrism and Bromus tomentelus and Poa bulbosa, Astragalus effuses, Dactilis glomerata, Ziziphora clinopodioides and Koeleria cristataamong showed the lowest production and consumption.