Journal of Rangeland
Year:2010 | Volume:4 | Issue:3|Papers Count:14

The nature of plant communities is one of the issues that have been always debated by ecologists and plant scientists. In fact, theories such as individualism and community units that included two main poles of these discussions are partly developed by mentality or problems such as sampling, calculation, analysis and conclusions. It seems that the use of new techniques such as remote sensing (RS) and geographical information system (GIS) can largely help to solve the above problems. In any case, it seems that a regional view of the above and survey that how the plants have been distributed by more advanced tools such as satellites sensors and computer besides of field observations can be more effective in comparison with traditional methods. In this study we used Landsat ETM+and IRS LISS III satellites data to verify that how plant groups distributed in Goloul va Sarani protected area. Field data included 143 training samples that were polled in homogeneous areas in each plant type. Then the samples were analyzed on the satellite images using the index of resolution and error matrix. The results showed that the highest resolution is related to the fields of pure alfalfa. Evaluation of training samples resolution about of the other vegetation classes also presented good results. Meanwhile, the plant communities maps that produced by classification of each satellite images showed clear differences with the other. These differences are likely related to differences of satellite sensors to detect of transition zones (ecoton).However, in this study it was confirmed homogeneous areas of vegetation that exist among of them the vague areas created by Tangled mixed communities.

More than 27 sheep breeds graze on Iran's rangelands. For estimation of grazing capacity in each region it is necessary to determine size and body weight, animal unit equivalent (AUE) and daily requirement for each breed. In this research, animal unit equivalent (AUE) and daily requirement energy for Kordi Khorasan breed was investigated. For this purpose, two herds of Kordi breed were selected. In each herd, 15 three years old ewes, 15 four years old ewes, 5 three years old rams, 5 four years old rams, 10 three month old lambs and 10 six month old lambs were selected. They were weighed three times including; in winter rangeland, when grazing from pasture and house keeping feeding period. According to the results; animal unit weight for herds (three and four years old ewe) was weight 45/9±0.76 kg. Therefore, animal unit equivalent (AUE) for rams, ewes and lambs were 1.42, 0.89 and 0.53 respectively. Two seasons grazing, two herds, two sexes two age and alternate affects herds*season grazing, herd*sex, season grazing* sex and sex*age were significant differed on average animal weight. According to MAFF equation, 1984; daily metabolizable energy requirement for maintenance condition by considering condition of rangelands and distances from watering points and plant density in lowland and highland rangelands was calculated 8.95 Mj (including that multiplied by 1.4). Dry matter requirement based on forage quality in lowland rangelands was calculated 1.47 kg. This amount based on 2 percentage of body weight (Holchek, s equation), is 0.92 kg that the different between amount, show that considering of forage quality for determinate of animal requirement is important.

The threshold concept of vegetation changes has an important role in natural plant ecology, but there is little information about the nature of threshold response of vegetation to grazing in rangeland ecosystems. The objective of this paper is to introduce thresholds based on vegetation changes of grazing gradient. In order to define the threshold concept at Zygophyllum eurypterum shrublands of cold season rangeland in Kerman province, two linear models and three nonlinear models (exponential curve, a piecewise regression and a sigmoid logistic) have been monitored on vegetation data of this area. The best models are two nonlinear models (piecewise and exponential) for plant vegetation of this ecosystem. The Plant Functional Types have been changed by nonlinear model. Based on water point distance, the changes in the trend of plant functional types of scrub forests, shrubs and perennial grasses that are palatable, have increased but the annual and perennial forbs were in decline. The results show that the sigmoid logistic model is not suitable for this area. On the other hand, two nonlinear models (piecewise and exponential) are better suited for these kinds of grazing management.

Karkas hunting prohibited region has 92100 ha area and is located at the central part of Isfahan province. This area is a part of arid and semi-arid ecosystem of Iran. The aim of this study was to investigate the relationships of dominant species of Karkas region with environmental factors including physiographic and climatic factors. Primarily, the vegetation types were distinguished at the filed with physiognomic-floristic-ecologic methods. The species data were gathered with stratified random sampling method using 10m×10m quadrats with recording percentage of the species cover, litter, bare soil and gravel within each quadrat. The physiographic factors including elevation and slope in addition to climatic parameters such as temperature and amount of precipitation were studied. Using Canonical Correspondence Analysis (CCA) Species relations with the environmental factors was studied. The results of study confirmed the drastic effect of environmental factors on dominant species establishment in Karkas region. It was shown that environmental factors interactions was the main factor on species establishment. The results of PCA showed that the most important climatic characteristic on the distribution and establishment of dominant species are precipitation and temperature, while elevation was the most important characteristic of physiography. Results revealed that increase in elevation leads to occurrence of cushion species. In general it could be concluded that in addition to the studied parameters, some other environmental factors play role in plants distribution of Karkas region.

Due to climatic and ecological factors impact, desertification is expanding in Iran. Therefore, identification of the effective factors on desertification is necessary. This study was conducted in a part of Qom catchment to find causes of desertification. Needed maps were prepared and using MPSIAC model, the rate of sediment was estimated. In addition, the environmental effective factors in desertification were determined. The results of geomorphological studies revealed the existence of seven dominant formations in the study area which are important in desertification.Formations included badland, Reg, Kalot, Sabkha as source area, rough land and the humid region.The soil is salty-sodic and due to clay abundance, the texture is heavy with low permeability. The annual sediment yield was estimated about 60944 tones. Analyzing different parameters through weighting method cleared that the arrangement of factors based on their priority in desertification is as follow, vegetation destruction, water resources and soil disturbance and climate. These factors lead to very severe desertification in the study area.

Determination of forage quality is one of the fundamental factors for sound management of rangeland. There are spatial and temporal variations in the nutritive quality of range species. In this study, forage quality of two salt tolerant grasses Aeluropus littoralis and A. lagopoides were measured at two phenological stages: vegetative and seed ripening. Study area was located close to Hamoon lake, Iran-Afghanistan border. Plant samples were collected at two growing stages and were chemically analyzed in laboratory. Data were analyzed by using ANOVA and Duncan’s test.The results showed that the forage quality of both species were higher in vegetative growth in comparison with the seed ripening stage. In both phenological stages, for all factors, A. lagopoides had higher forage quality than A. littoralis (p<0.05).

In this research the most effective factors of soil on plants distribution was investigated in Kuhe- Namak rangelands of Qom Province. For this purpose sampling was performed based on randomized-systematic method with 90 plots along six transects.15 plots (4 m2), established along each transect and vegetation characteristics were recorded. At the initiating and at the end of each transect, a profile was dug. Soil samples were taken from 0-20, 20-40 and 40-80 cm. The properties of clay, silt, sand, organic mater, lime, gypsum, magnesium, calcium, sodium, chlorine, potassium, carbonate, pH and EC were measured. To determine the major factors affecting plants distribution, principle component analysis (PCA) was used. The results showed that among studied edaphic factors texture, EC, magnesium, chlorine and sodium had the most influence on plants distribution of the study area.

Autecological study ofVicia villosa was performed in Kohgiluyeh and Boyerahmad province from 2002 to 2004. At first, geographical distribution of V. villosa was determined on province map. Then three habitats namely Firooz Abad, Maleh Shureh and Dali Beigi were selected as study areas. Climatic, topographic and edaphic properties of mentioned areas were studied. Seed properties, root structure and different animals preference for grazing from V. villosa was evaluated. Phenological studies were done for two years. Results showed that this species distributes in elevation ranging from 900-2500 m asl. Its habitat climate is semi arid and temperate to cold Mediterranean with annual mean precipitation and temperature of 870 mm and 14.8 Co, respectively. There is no limitation in view point of slope aspect while suitable slope for its occurrence ranges from 5-15%. Germination percentage was obtained 11%. Vertical and horizontal root depths were recorded 150 and 75 cm, respectively. Exploitation by goat was more than sheep and cow. Vegetative growth initiates in March and seed falling occurs in July.

Seeding is an important methods of range improvement practice in the world. Optimum seed quantity is a challenging issue worthwhile to be studied. These studies are looking for a balance between the amount of seed and quantity of forge they can attain. The principle goal of this study is to searchfor appropriate amount of seed to produce satisfactory amount of forage and seed through cultivation of Agropyron elongatum and Agropyron desertorum. Factorial random design total black was used for the experiment with four frequencies. Two species: A. elongatum, A. desertorumand three level of seed amounts (2.5, 3, 3.5kg/ha) were used for the study for two years. Rows were 5×3m distanced 1 meter from each other. Seeds were cultivated on rows on every 50cm. Results showed that A. elongatum, seed and forage production were significantly in consistent with the increases seeding intensity from 2.5 to 3 and 3.5 kg/ha. This suggests that usage of more seeds, i.e. more than 3.5 kg/ha may increase the forage and seed production. In A. desertorumlevel of 3 and 3.5kg seeds per hectare doesn’t show a significant effect on seed and forage production. For levels of 2.5 and 3kg seeding per hectare the result showed significant effect on seed and forage production. Hence, 3kg seed per hectare for this species can be an optimum amount for an acceptable function in terms of seed and forage production.

Land as one of the integral parts of production inputs, not only, plays a critical role in agriculture and natural resource management but also is important part of national economy. Landuse changes as a function of environmental and human driving force has caused serious impacts on environment, economy and society over the past decades. Thus, having knowledge on the type of landuse and its changes over the time is one of the main issues for planning and policy making. Current research was conducted to investigate the trend of land use changes in Taleghan throughout remote sensing and GIS. For this purpose, based on multi-temporal data of TM (1987) and ETM+ (2000), land use maps were extracted by digital image classification and maximum likelihood procedure. The extracted maps with the field observation data were imported into GIS and the amount and type of changes were calculated using change detection extension. According to the results the trend of landuse changes in range and abandoned lands was considerable. Abandoned lands have been increased from 8% to 16%, while rangelands showed the major reduction of 11%. The amount of reduction is very low fpr orchards, agricultural lands and rainfed lands. Due to spectral similarities between abandoned areas and rangelands the necessity of application of more accurate method for land use change detection is needed. On the other hand, because of close relationship between landuse changes and human driving force it can be concluded that such a landuse changes pattern are related to population status that calls for more researches.

Salt and drought stress are of high importance in seed germination and seedling establishment.Priming has been successfully demonstrated to improve germination and seedling emergence in seeds of many crops, particularly seeds of vegetables and small seeded grasses.Agropyron cristatum (L.) Gaertn provides thin and sensitive seedlings. This species could be considered as a suitable plant for seeding plans in arid and semi-arid regions as well as saline soils of Iran. The objective of current research was to evaluate priming methods for increase of germination properties and initial growth parameters under salinity and drought stress. For this purpose factorial experimental completely randomized design in three replications were performed. First factor was priming treatments, the second third factors were Iso-osmotic solution and the stress levels, respectively. The results showed that the effect of main treatments and their interactions (pretreatment, levels of stress) was significant on germination speed (P £ 0.05). Increase of stress levels resulted in decrease of germination so that in -8 bar germination stopped. Totally, it was found that applied treatments were not affective for improvement of germination and initial growth properties under stress conditions.

Seed priming could be as a way to improve seed germination behavior under moisture stress conditions. This experiment was carried out to determine priming effects on seed germination of tall wheat grass (Agropyron elongatum) under control and drought stress (Y=-0/8 bar) conditions. Two 3-replicated factorial experiments based on CRD design were carried out in 2009. In control experiment, seeds were primed in -4, -8, -12, -16, -20, -23, and -25 bar polyethylene glycol (PEG) and urea as well as distilled water (hydropriming) for 8, 12, 16, 20 and 24 hours at 25oC. Seed priming increased germination percentage, germination speed, seedling length, seedling dry weight, root/shoot ratio while decreased mean germination time. In this study, increasing priming duration and osmotic potential of priming solution had negative effects on measured characteristics. The most promising control seed treatments including urea and PEG with -4 and -8 bar as well as hydropriming for 12 and 24 hours were advanced to drought stress experiment. Also, it was shown that priming with urea had better results compared toother treatments. It is concluded that seed priming treatments with fertilizers may serve as an appropriate treatment for advancing germination under optimum and drought stress conditions.

More than 53 percent of Iran area is covered by rangelands. The economy of noticeable number of families depends on rangeland ecosystems. Therefore, the participation of ranchers in rangeland improvement and reclamation projects is needed. The purpose of this study was to analyze and determine the effective social factors on ranchers participation in range management plans in Ghaemshahr county using X2 correlation test and Logit regression. In this study factors such as age, job, education, land ownership and knowledge about range management plans were used. Based on simple randomized sampling, 50 ranchers from 29 traditional (common) units were selected from summer and winter rangelands of Ghaemshahr county. The findings of this research showed that among understudy social factors degree of knowledge of ranchers about range management plans was the most graceful one to absorb their participation in mentioned plans. Results revealed that 1 percent increase in degree of knowledge leads to 3.04 percent increase in ranchers participation. In other words, ranchers participation would increase by 0.58 units if their knowledge about range management plans increases. It was cleared that age had a significant negative effect on ranchers participation. Despite their high experience in range management, this may be is due to their physical disability for participation.

Land degradation, soil erosion and sediment yield are important problems in developing countries. Towards this, different managerial treatments are being used to alleviate consequent impacts. How even, evaluated of effectiveness of study treatments in controlling after said resultants has been take in to account. The result study was therefore formulated to study the role of free grazing and short term exclosure treatments on sediment yield in a part of Kodir summer rangeland located in south eastern of Nowshahr, central Alborz highlands, as a representative for Iranian Northern summer rangelands. The sediment yield was measured in 0.25 m2- square plots by applying rainfall simulators with 1.6 mm.min-1 intensity. The results were them compared on storm basis with the help of ANOVA and Tukey test. The results of the study verified the significant difference (p<0.005) in mean values of sediment yield and concentration. The results also revealed that the rate of sediment yield and concentration in free grazing was almost 1.62 times more than these reported for short term exclosure treatment.