Journal of Rangeland
Year:2010 | Volume:3 | Issue:4|Papers Count:20

Topography is one of the most important factors that affects on vegetation cover. Land units are the homogeneous units which are classified using the topographic and soil factors. In this research, the species richness and life form species in key area of two land units (with the same vegetation type) of Hossein-Abad winter rangelands at Qazvin province were studied by using Whittaker's plots. After determining of key areas on land units, two Whittaker's plots of 0.1-ha were established in land units. In each of Whittaker’s plots, from 0.1 to 1000 m2, the name and the number of each species and their life forms were recorded. Applying PCA ordination method, four Whittaker’s plots were grouped. By using linear regression models, two appropriate regression equations were calculated for each of land units. In order to comparing the regression coefficients, the group regression model was used. The results showed that the species richness in land unit of 2.1 has a significant different in comparing to land unit of 3.3 (P<0.05) and the species richness in the first unit is higher than the second unit. Comparing of life forms composition in 2.1 and 3.3 land units implied that the utilization rate in the first unit is less than the second unit.

Collection of data on vegetation is a necessary task for range managers. Vastness of the rangelands plus variation in plant communities requires sampling plant vegetation. The question of “How many samples should be placed to get enough data while spending the least money and time” stands as a mainstay of these types of data collection. This research investigates the efficiency of different statistical formula for determining optimum sample in steppe range lands of North-East of Golestan province.  In sake of sampling uniformity alongside with four 50 m transects we placed 200 quadrates to provide totally 1600 samples from all 8 geographical aspects. The canopy cover of total plants was recorded. Total canopy cover percentage of 10-100 primary quadrates of dominant plant[this part is not understandable either], average of these samples, average of samples of community and the ratio between average of samples and community in acceptable error levels (a= 1, 2 ,2/5 ,3, 5, and 10 percentage) calculated separately. The results of this research showed that number of samples could be determined through N= (CV/E)2 equation at (a=2 percentage) and number of 30 rimary plots had the most accuracy ratio among other formula.

Autecology of Eurotia ceratoides was studied. Study area is located in Nodooshan, Yazd, Iran. selected sites were within three different elevations, i.e. 2200, 2300 and 2450. Sampling was done in a random-systematic way in these elevations: 2200, 2300, and 2450. In each elevation, in 5 points, Eurotia ceratoides bushes were selected, that they hadn't been changed through the examination. Sampling was executed in three stages of growth, flowering and seeding of the bushes. In laboratory, calcium, phosphorus, nitrogen and potassium were evaluated. For examination, analysis of variance and Duncan were used. Results showed that this species is distributed with a desirable ecological range in mountains with 7.8-8 pH, 0.2-0.12 EC dc/m in 1500-2500 meters elevation. According to 10-year statistics, the average rate of rain fall in this habitat is 98.3 millimeters and average annual temperature is 14.4 centigerad. This plant grows as a shrub with the height of 25-40 centimeters. Examinations showed that density, coverage percentage and production are directly related to height increase. Vegetative growth begins at late February, flowering occurs in April and May. Seeding happens at late May to mid June. Results also showed that the highest amount of plant protein exists in flowering time.

Rangelands of Kabotar koh village of Gonabad city, Razavi Khorasan was selected to study. Its dominance vegetation type is Artemisia sieberi. Cover, density and distribution pattern are three quantities that was used as the indices[for what?]. Two places under different management behaviour , seasonal(SG) and continuous grazing (CG) were selevted to look through their vegetation cover.Thus other factors like relief, climate and soil was more oe less the same.with respect to landform and geology identical sites were selected on CG and SG by use of ARC GIS9 software. In 5 of the sites, 40 Transect with 30 meters length established and in every Transect, cover, litter, number of Legs, rock, gravel and bare soil were calculated. For analysis of cover data, Independent Samples T Test, for density, spatial indices of nearest neighbourhood and nearest person and for distribution pattern, spatial indices of Hopkines Index, Johnson and Zimer's Index and Ebrhardt's Index were used. Results showed that elongation of grazing period does not make any changes on cover percent of A. sieberi but would decrease the density..

Grazing is one of the most common land uses of the world’s rangelands, and has the fundamental potential to alter C and N storage in these ecosystems. Gazinant period is an import factor to this alternation. This research focused on the influence of grazing on carbon and nitrogen storages in ecosystem of arid shrubland of Iran that covered by Artemisia sieberi species on the Semnan Province. To estimate C and N stored in biomass and their distribution in plant compartments, simple biomass equations were extended for each treatment. Carbon and nitrogen storage and their distribution in different treatment, main stores where organic carbon accumulates as biomass (above ground and belowground), in soil (0-25, 25-50, 50-75 cm) and through litter were sampled in November 2008. Result show that C and N in aboveground, belowground biomass, and Litter were decreased significantly with grazing in both regions in comparison with non-grazing treatment. The most decreases was occurred on the aboveground biomass in both regions, Ghooshe and Peyghambaran. Although there was a significant decrease in content of C and N sequestrated in Ghooshe region, it was not any significant difference in C storage in Peyghambaran region in response to grazing. There was the significant difference in soils C and N storages in Ghooshe region, but there was no significant deference in the soil of Peyghambaran region. However soil N contents were decreased significantly (P<0.05) by grazing in all regions. Soil has the highest amount of ecosystem’s C and N in all treatments. In generalthe effect of grazing on C storage in Ghaooshe region was remarkable and there was not any significant difference in C storage of ecosystem in Peyghambaran region. Grazing has a proven effect on ecosystem elements such as C and N storages but response stringency of ecosystem to grazing and its magnitude is depended on some factors that the most is intensity of grazing.

Range capacity is based on amount of forage production. One of major goals in natural resources management is describing yield of rangelands for determination of range capacity. Estimation of range capacity via clipping and weighting method is very time and money consuming. Selection of methods that are accurate, simple, fast and cheap therefore, is a wise action. In this study, evaluation of yield of tree grass species, Stipa barbata, Bromus tomentellus, and Dactylis glomerata, was done by netted plate in Minavand sub-basin of Taleghan catchment with 30 replication and camera distance from frame of netted plate was between 50 and 75 cm. At first, the equation between yield, as independent variable (Y) and number of squares that covered with plant twigs in netted plate as dependent variable (X) was determined and considered different methods of squares or nets counting and statistical analysis. Utilization for every 3 species in 3 levels (25%, 50% and 75%) was also, determined. Because the linear equation between yield and number of squares in all cases was not significant, exponential equation was used. The most observed correlation (r2) was for ¼ squares and more, then for complete squares and after that for ½ squares and more, and the least r2 was for the squares that completely covered with plants. For estimating utilization, we used the independent sample T test and we observed significant relation for Stipa barbata in 75% level for complete squares and ¼ squares and more, but for other species and methods for counting were not significant. Consequently, the netted plate (grid) method is suitable method for evaluating yield in grasses, but is not suitable for determining utilization.

Fire is one of the effective ecological factors influencing the growth, development and evolution of plant communities especially in arid and semi arid areas. Knowledge of the effects of fire on different components of an ecosystem is important for post-fire vegetation management. Changes in vegetation due to fire can cause changes in the amounts of seeds in the soil. Seed reserves in the soil seed banks play an important role in vegetation dynamics after fire. In this study, the effects of fire on species composition and subsequently on soil seed bank were studied in Bamoo National Park in Shiraz. The study was carried out on two sites (Chah Sorkh and Palayeshgah), each with a control area (unburned) and two burned areas 1-year and 5 years old after fire. Soil samples were collected from two soil depths, 0 to 5 cm and 5 to 10 cm. Samples were put in greenhouse for seed germination and seedling identification. A total number of 1747 and 1482 seeds/m2 was found in Cah Sorkh and Palayshgah, respectively. About 73% seeds in Cah Sorkh and 79% seeds in Palayshgah were germinated from upper soil layer (0-5 cm). Most seeds in the soil seed bank of two sites belonged to Aegilops triuncialis. Also in both sites Gramineae, Compositae and Papilionaceae were abundant in soil seed bank. Fire in both sites changed the seed bank composition and density in comparison with control area. There were few species common between burnt areas and control area. Other species were restricted to either burnt or control areas. We also found different specie composition in the soil seed bank of two areas with differing age since fire in two sites. Few species were found in both standing vegetation and soil seed bank and most species in vegetation were absent from soil seed bank.

The purpose of the present research is to investigate some soil characteristics (texture, EC, S.A.R, organic matter, gravel percentage) in 35 habitats of Calotropis procera L. in southern rangelands of Fars province. Selective sampling for choice habitat. In this regard variance analysis was made use of. The results indicated that only texture (clay, silt and sand) was significantly different in all the 35 habitats when Duncan test was used. Regarding results of this research, Calotropis procara L. could be available on vast ranges of edaphic condition such as surfaces with gravel up to 50%, EC to 10 (ds/m), SARto 8.65, all texture and soils with poor organic matter (0.07).

More than 90% of 165 millions hectares of Iran's surface area are located at Iran plateau and nearby seven millions hectares are salty and desert region. There are 60 playas in Iran embracing different geological structure. Most researches on these playas are inthe field of geology and meteorology. Marginal region of playa shows clear environment gradients. Analysis of relationships between vegetation and environmental conditions in the playa of Kashan region is the aim of this study. Vegetation samples were taken from 35 modified Witthaker plots and cover, density, frequency of all species were recorded in the plots. Soil samples also were takenat the same time from the plots and some chemical and psychical properties of soil were indicated through common methods. sixty species from 16 families were collected. The largest families were Chenopoiaceae, Graminaceae and Compositae, representing 16.6%, 15%and 13.3% of the total flora, respectively. Vegetation was classified via two-way indicator species analysis (TWINSPAN) techniques and six vegetation groups were recognized. Ordination techniques as detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA) were used to examine the relationship between the vegetation and environmental parameters. Classification of TWINSPAN was confirmed by results. Analysis with DCA and CCA, suggesting that there is a relatively strong correspondence between vegetation and environmental factors. CCA axis 1 was highly associated with carbonate, EC, bicarbonate, K/Na, Ca/Na; lime Ca/Mg, Cl and pH while CCA axis 2 showed significant correlation with pH, calcium, gyps, clay and bicarbonate. These gradients were related closely to the first two canonical axes, and accounted for 24.8% of the species–environment relationship in the study sites.

Rangeland ecosystems have approximately half of the worldsٰ land area and they store over one third of terrestrial biosphere carbon. Effect of exclosures, grazing abandon, on soil carbon sequestration and plant biomass, in addition to distribution and potential of carbon sequestration was studied at Sisab research station in semiarid rangelands of north Khorasn province. The site has been closed to grazing for 22 years. As a control results were compared with grazed neighbouring areas. The content of above ground and under ground biomass carbon, litter carbon and soil organic carbon (in two depths 0-15 cm, 15-30 cm) was determined. The result showed that the total carbon sequestration of ungrazed and grazed area were 39.79 ton/ha-1/year-1 and 28.97 ton/ha-1/year-1 respectively The results of carbon distribution showed that the soil organic carbon content was more than 97% of total carbon sequestration. In addition the carbon content in underground biomass was higher than above ground biomass. It was concluded that the exclosure management increased the carbon sequestration by approximately 0.5 ton/ha-1/yr-1. result of the study also suggests that soil is the most important sink for organic carbon storage in these rangelands.

Continuous use of the semi-arid Ghareh Aghach rangeland in Isfahan province is not only detrimental to animal production and vegetation cover, but also reduces the stability of the soil and increase soil erosion which ends up with range degradation. . The goal of this study was to present a model for range management based on grazing capacity and vegetation value by which the problem of range degradation is mitigated. For the model an index of classification management (IRC), was designed to determine the range suitability for livestock grazing. In this model, rangeland is classified into three suitability classes. The first is conservation rangelands, which is not suitable for livestock grazing, due to degradation problem. This rangeland is mainly devoted to conservation, ecological and social values; the second class is moderately productive rangelands, which is dedicated to multiple rational land uses and the third is intensively productive rangeland, focusing on maximum economic effect. The results of this study showed that, from 7158.81 hectares of semi-arid Ghareh Aghach rangelands, conservation range type occupies 4695.92 ha, accounted for 65.6% of rangeland area. In these range types, grazing should be eliminated to allow restoration of degenerated areas and to further improve the environment. Also, agricultural application, such as dry farming, planting, seedling and inter-seeding, should be used to enhance the productivity of these range types. Moderately production range type covers 2462.89 ha, accounted for 34.3% of rangeland area. Livestock grazing should be allowed based on grazing capacity. For improve potential yield of this range areas, some application such as rotational or deferred grazing system could be applied. If desirable species in plant composition is limited, range should be kept a way from grazing. Continuous use of Ghareh Aghach rangeland has led to low available forage and low frequency of desirable species in plant composition. In semi-arid Ghareh Aghach region, no productive rangeland was available.

Allelopathic compounds play important role on biological diversity and productivity of ecosystems. In this study seeds of A. sieberi were treated with its foliage extracts. Whereas in previous works effects of foliage extracts of this species were investigated on other species seed germination and growth. Seeds were collected from mature plants of A. sieberi in Kolah Ghazi National Park located in 20 kilometers southeast of Isfahan. After pre chillig treatment seeds were put in petri dishes and treated with 10, 20 and 30 percent foliage extracts and compared in a completely randomized factorial design. Four seed populations were used in this experiment. Percentage and rate of germination shoot and root lengths as well as allometric ratios were determinated. Data were analysed with SAS Statistical program. Results indicated that increasing level of extract caused reduction of percent and rate of germination as well as shoot and root lengths. As a consequence of extracts increase levels of alometric ratio also increased, showing more pronounced effects of extracts on root growth. Negative effects of A. sieberi extract on seed germination and seedling growth of this species is probably a mechanism for plant density regulation according to site potential of natural vegetations.

Importance of Rangeland as a source of feed for livestock and natural ecosystem preservation is inevitable. Investigation of effective factors on their preservation and development toward sustainability of the production is important In this study effect of economical-social factors in range management projects in Ghaemshaher, Mazandaran province, Iran is studied. For the task 50 questionnaires were given to Najarkola, Osbukola and Gardanesar people. The result of regression Logit model showed that variables of income, number of livestock, rangeland square, extensional training and education have positive and significant effect in acceptance willingness to accept of project. Also variable of age has negative and significant effect. The variable of income has most elasticity. If this variable is increased equal to one percent, probability of willingness to accept is increased equal to 0.3 percent. Also the variable of age has most marginal effect. If this variable is increased equal to one unit, the probability is decreased equal to 0.055 units. At the end, some policy suggestions to increase willingness to accept of Rangeland Management Projects.

Application of remotely sensed data for estimation of surface temperature is a new method, tremendously reduces the cost of current temperature measurement techniques. These data prepare distributed data with a high spatial resolution for the users. Sebal algorithm is a new method to determine evapotranspiration and other thermal parameters, which has satisfactory results. In this research, Sebal algorithm has used to process the ETM+ data in Vardin watershed, Ahar city, Eastern Azarbayejan province, Iran. The hypothesis of this research is the reliability of remotely sensed estimation of temperature in comparison with observations. The main objective of this research is to reveal the accuracy of this method and to find the best method. Existing temperature observation in meteorological station used simultaneously. The result has shown the differences between observed and simulated temperature values are negligible.