Journal of Rangeland
Year:2009 | Volume:3 | Issue:2|Papers Count:21

High grazing pressure has been considered as the main reason for degradation of Iran's rangeland over past few decades. A key question for range management is therefore whether temporary exclusion from grazing would lead to spontaneous regeneration of the vegetation. If so, it is important to know how long this regeneration will take and whether the regeneration pathway is the same in all sites. A long-term exclosure experiment was established to assess effects of grazing exclusion on rangeland recovery in arid and semi-arid rangelands in Iran. The experiment was carried out in 17 rangeland sites in central Zagros region. At each site, an exclosure and inside each exclosure seven permanent plots (1.5 ´ 2 m) were established in 1983. After 19 years (2002), vegetation, including cover and density for each species, total vegetation cover, litter cover as well as annual forage production, were measured in these seven permanent plots and also in 10 randomly located plots (1.5 ´ 2 m) outside each exclosure. The comparison between inside and outside exclosures showed that after 19 years, total vegetation cover, litter cover, annual forage production, the number as well as the relative abundance of grasses and legumes, and the percentage of palatable plants were significantly increased inside exclosures. The overall similarity between different sites inside exclosures was also increased. In conclusion, 19 years grazing exclusion has changed the species composition of the vegetation in most sites. This study confirms convergence of vegetation development during the secondary succession.

The first step in ecosystem management is the determination of effective factors on species distribution and diversity. In this paper the relationship between species diversity of Taleghan rangelands and environmental factors has been investigated. For measuring vegetation data, according to sensitivity of species diversity parameter to plot number and area, the proper area of sampling plot was determined by least area method and the number of plot after the primary sampling was determined by statistical method according to vegetation variations. Then, sampling in each unit was done along three 150 meter transects. 15 plots (1 m2), established along each transect in 10 meter distances. The kind and the amount of existing species and the percentage of vegetation cover were determined in each plot. At the beginning and at the end of each transect, a profile was dug and soil. Sampling was done from 0-30 centimeter. Among soil properties, clay, silt, sand, organic material, lime, PH, EC, azote, phosphorous, acidity, Electrical conduction potassium, were measured, After collecting data, Shanon-Winer species diversity and Simpson indices were determined using Ecological methodology Software. To determine the major factors affecting species diversity variations, Principle component analysis was used. The results showed that among studied factors aspect, texture, lime, potassium and depth of soil had the most influence on species diversity.

A study was conducted to examine the relationship between litter weight and vegetation parameters including canopy and litter cover and biomass in steppe vegetation of Khabr National Park. According to the sample size equation, 90 plots of 1-m2 randomly were placed within study area. In each plot, the percentages of canopy and litter cover are estimated and the weight of litter is measured. The results indicate that the mean litter weight is 83.53gr/m2. For calculating standing biomass, double sampling method is used. According to this method, standing crops is harvested to the ground level in 35 quadrats of 90 plots. Air dry collected plant materials are weighted. By using regression equation, the amounts of biomass in other 55 quaderats are estimated. Correlation matrices and stepwise regression model were used to show the relationships. Finally, just canopy cover was remained in model which had linear relationship with litter weight and the correlation coefficient was 0.95. Therefore, canopy cover is an appropriate parameter to estimate litter weight in arid and semi arid shrublands.

Most species of Umbelliferae have medicinal and industrial values and also are used for forage production and soil conservation in Iran. Prangos ferulacea (L.) Lindly from Umbelliferae is the dominant species of Iranian Jashirzar. In local knowledge it is known as the best rangeland plant which aware of its qualitative changes. Jashir is collected by traditional rangeland managers when it is green and toxic for livestock and then dry them to feed livestock. This caused a disturbance on its reproduction and also the degradation of its habitats by ranchers. Therefore, conservation and sustainable use of this species depends on knowledge of environmental factors influencing its natural habitat and also utilization according to the ecological aspects. This study aimed to assess soil and topographic factors using canonical correspondence analysis (CCA) on five Jashir habitats (Timargon, Asopas, Khoram Bid, Simakan and Koh Bel) in summer rangeland of northern part of Fars province. Percentages of canopy cover and species frequency in key areas have been recorded and soil sampled in two depths (0-10 cm and 10-50 cm). Data were analysed using CCA in PC-ORDversion4.17 package. Results showed that the distribution pattern of Jashir was correlated with some edaphical factors such as the amount of N, P and soil texture as well as with some topographic factors including slope and elevation from sea level. Management and sustainable utilization of these habitats are possible under grazing systems compatible with ecological and climatic conditions and considering scientific framework of rangeland management.

Vegetation cover is one of the most important factors for sustainability of ecosystems and catchments; thus recognizing and understanding factors that affect growth and development of vegetation societies is necessary. The aim of this study is to investigate the relations between "Astragalus gossypinus" with some environmental factors (soil characteristics, slope, aspect and elevation) and identify the most important affective factors in mountainous rangelands of central Zagros. So, three elevation and slope classes and four aspect (skirt) classes have been determined in the study area. Flora and vegetation types were studied by physiognomic- floristic method in the field. The factors of vegetation were measured by transect using systematic-randomized method. Four transects (100 m) and 5 plots were used. Three soil samples (complex) in each area collected in 0-50 cm and parameters such as pH, EC, N, P, K, TNV, OC and texture were measured. Investigating of the relations between density and cover percentage of A. gossypinus (dependent variables) and soil and topographical factors (independent variables) has been done by multiple regressions. Statistical analysis of data showed that density and percentage cover of A. gossypinus have significant linear regression with soil and topographic factors. In topographic factors; southern aspect, 20%-30% slope and 2100-2300 m elevation and in soil factors; pH, K, sand and silt have -most relationship and significant role to anticipate of density model. For anticipation of cover's model, in topographic factors; southem and northem aspects, 20%-30% and 30%-50% slope and 2100-2300 m and 2300-2500m elevation and in soil factors; pH, K, sand and silt have most relationship and significant role.

Soil Erosion due to water is a major environmental problem in many parts of the world. Accurate estimation of water erosion is very important for the assessment of potential soil loss and storage capacity in reservoirs due to sediment deposition. The physically based Water Erosion Prediction Project (WEPP) model provides event-based runoff, erosion and sediment yield estimates. In this study surface runoff and soil loss simulated by the WEPP hillslope model were compared with measurements from two experimental plots containing rangeland vegetation. These plots were 12.5 m long and 2 m wide with slope gradient of 34%. Results showed, in general, WEPP hillslope model simulated fewer runoff events than measured data. The model tended to present better results when effective hydraulic conductivity was calibrated. Correspondence between measured and simulated runoff and sediment data were represented model efficiency coefficient 0.86 and 0.87, respectively.

The study examined the grazing systems in range management plans via a participatory evaluation. This research performed in 1386 in Semnan province. All of experts in natural resources offices and livestock manager that exploit/own selected ranches were whole/reference population in this study. Using stratified random sampling method and applying Cochran formula, the sample volumes 30 were estimated to select from Range management Plans. Result showed that grazing systems in range management plans for winter rangelands in this area was unsuccessful/failure (%77). Some important reasons of this unsuccessfulness is no participation of livestock managers(%33), no attention to special affairs of pastoral society (%25), no adaptation with natural conditions (%22) and no correct designing for grazing systems (%20).

Optimal intake of nutrients by grazing animals can be achieved if we were able to understanding and controlling their dietary habits and preference. Without understanding these behaviours, correct management of rangelands is not possible. Therefore, in desert rangelands in Qom province two fenced enclosures (1 ha. area) were constructed in which plants production and intake measured during grazing period. The feeding behaviour of three Zandi ewes (1, 3 and 5 years old) in free grazing system was evaluated considering the plant palatability and preference value based on close observation method (recording films by video camera) in each month of grazing season. Then diet composition and preference index for each plant species calculated and compared. Grazing cycle) distance and motivation speed and time spent for grazing, resting or walking) were assessed using a GPS mounted on the back of sheep. The results showed that during grazing season, Tamarix passerinoides And Alhagi camelorum- in first and second vegetation type - had the highest preference index, respectively. The highest diet composition was related to Halocnemum strobilaceum and Alhagi camelorum. Animal experience, plant's flavor, plant cover and composition were the most effective factors on sheep preference. In Houze sultan, sheep showed browsing behaviour. There were significant differences in diet selection (p<0.01) among three ewe ages. Considering to plants phenology and soil moisture conditions, Presence period of Livestock in Houze sultan range was suitable but a rest- rotating grazing system can be suggested in period of flowering of Tamarix sp.

Different plant species in different phenological stages don't have similar palatability. Therefore, in range management studying the palatability of forage species can help us select proper plant species with less palatability fluctuations in different stages and increase the potential of efficient utilization of rangelands. In this investigation, the palatability of 3 plant species from Gramineae in different phenological stages and its relationship with leaf: stem WP ratio was studied. The palatability of 3 grass species existence in 2 plant types was measured by camera for sheep and goat in 3 phenological stages. Then analysis of variance and mean comparison (Tukey's test) were done on data. The results showed that in 3 species there is relationship between palatability and leaf:stem WP ratio in second and third phenological stages and in both stages the grass species with the highest leaf:stem WP ratio had the most palatability. In growth stages, Dactylis glomerata was more palatable despite of having lower leaf:stem WP ratio than that of Bromus tomentellus. However, in mentioned stage, Agropyron trichophorum with the lowest leaf:stem WP ratio had the least palatability. Therefore, with conducting more studies, we can find the relationship between leaf:stem WP ratio and grazing time percent in different climates.

Rangeland health has defined as the degree to which the integrity of the soil, vegetation, water and air as well as the ecological processes of rangeland ecosystems are balanced and sustained. By determination rangeland health attributes we can judge about management practice effects. the present study was carried out in Meyghan desert of Arak in order to determine the most important ecological indicator to achieve suitable for rangeland health and condition assessment using LFA model. In this region by LFA model and 11 soils surface indicators were measured on four transects 50 m and effects of patch were investigated with functional characteristic including stability, infiltration and nutrient cycling. The Results showed that planted species (Atriplex canecence, Nitraria shoberi, Haloxylon persicum) had a higher function than endemic species (Artemisia sieberi). Also all species had significant relation with inter patch. Atripilex canecence had higher function than another species. 

Salsola rigida is one of the most palatable species of steppe and dispersedly semisteppe areas. The investigation of various features such as its reproduction seems to be essential for vegetation expansion projects in abovementioned regions. The objective of the present study was to compare effects of different treatments on promoting seed germination in Salsola rigida. This study was conducted to evaluate the effects of KNO3 (%0.2 and %0.1) and GA3 (100 ppm and 300 ppm). For this purpose, a completely randomized design with four replications in two forms of experiments was done: treatment irrigation during the germination period and presoaking. The results of analysis of variance showed that the effect of various treatments were significantly different. The treatment of 0.2% KNO3 in presoaking had the highest seed germination percentage. The result obtained from gibberlic acid 300 ppm influence was a little smaller than 0.2% KNO3. Totally, this research cleared that presoaking treatment was more effective on germination stimulation so that presoaking with 0.2% KNO3 increased germination up to 100%.

Ferula gummosa and Ferula asafoetida are species of flowering plants in the family Apiaceae. These plants have certain uses as industrial, medicinal and forage species. Due to seed germination problems, some seed dormancy breaking treatments were used. In this research used four breaking treatments with different levels. Treatments were as follows: Washing (Three levels), prechilling (Two levels), washing and chilling (Four levels) and chemical scarification (Four levels). The results showed that pre-chilling for 60 days period is the best treatment for breaking seed dormancy offerula gummosa, and washing plus chilling (14 days at +5°c) is the best treatment offerula asafoetida. The results showed that washing treatment has not significant effect on breaking species seed dormancy.

Endo-mycorrhizal fungi are useful soil microorganisms, which can be used as a biological fertilizer for providing nutrient requirements for plants (particularly phosphorus). Two field experiments were carried out in research farm of Shahrood University of Technology to investigate the effects of one species of arbuscular mycorrhizal fungi (Glomus intraradices) on growth and forage production of two annual medics (Medicago polymorpha and M. scutellata ) in different conditions of soil phosphorus. Each experiment was arranged in a factorial randomized complete block design with two treatments of mycorrhizae (with inoculation and without inoculation) and phosphorus fertilizer (0 and 65 kg P/ha) with 4 replications. The results were shown that inoculation of Medicago polymorpha and M. scutellata with Glomus intraradices had positive and significant effect on root colonization, shoot and root dry weight, but had no significant effect on root and shoot length, dry weight and number of sheath. On the basis of the results of this study, mycorrhizal inoculation increased 30% of forage production in both annual medic species Medicayo polymorpha and M. scutellata Application of phosphorous chemical fertilizer also increased forage production as the same amount as mycorrhizal inoculation, but it decreased root mycorrhizal colonization in both plants significantly. With due attention to positive effects of mycorrhizal fungi on forage production of Medicago polymorpha and M scutellata, it seems that mycorrhizal fungi can be used as a biological fertilizer instead of phosphorus chemical fertilizer, which have no environmental problems compared with phosphorus chemical fertilizer in sustainable agriculture.

Iran ranges have one of the most reach floras in the world that the main part of this flora is medical plants. Many compounds in essential oil of these plants can use in food and medical industries that should attend in multiple use of ranges. One of the medical plants in Iran ranges is Camphorosma monspeliaca L. This research to identification and detennination yield of essential oil composition of Camphorosma monspeliaca L. in three main habitat (Arak, Hamedan, Shahr-E-Kord) in two phonological stages including vegetative and flowering stages were done. The results show that the total yield of essential oil changes between 0.1% to 0.2%. Overall 114 components were identified of total essential oil of Camphorosma monspeliaca L. in three mentioned habitats the most components belong to Hamedan and the lowest belong to Arak in flowering stage (Hamedan=103, Shahr-E-Kord=78 Arak=55). Through identified compounds 10 common compounds had the most yields in flowering stage in three areas including: