مجله مرتع
سال چهارم شماره 2 (پیاپی 14، تابستان 1389)

In order to study of phenological stages on forage quality, 19 species of vegetation were selected. These species are palatable and important in Rangelands of Saral Kordestan. Samples were collected in three phenoligical stages of vegetative growth, flowering and seed production. Plant samples were analyzed to determine N percentage as well as Acid Detergent Fiber (ADF). In order to analyze of data, using split plat statistical method with randomized complete design in 3 replication of 57 treatment for each location. According to the phonological stages of growth had a significant influence on forage quality. In all species, the amount of CP, DMD and ME decreased with progressing growth stages, while ADF contents increased. The results are important to determine suitable time for grazing and estimation of grazing capacity in rangeland of Saral.

Managing rangelands appropriately and efficiently requires sufficient knowledge about environmental factors and their effects on vegetation. This study is focused on applying multivariate analysis to determine the relationship between plant properties (vegetation cover and density) and physiological parameters of rangelands. Study area which is about 460 ha is located at Hezarjarib, Mazandaran province. Slope, aspect and elevation maps were overlaid using a GIS environment to reach almost homogenous land mapping units in which samples could be taken. Then by completely random sampling some range plants were sampled. Multivariate analysis showed that variation in percentage of canopy cover and density of the species were influenced by aspect, slope and elevation. Integration of the maps resulted that each plant species grows in special morphological conditions which is different from other vegetation types.

In this study, floristic composition and plant richness of saline plain of Aghghala and Ghomishan located at eastern border of Caspian Sea were investigated. Data on floristic composition of land units were collected so that species richness could be distinguished. For that the Whittaker's plot were placed on hills of Gharaghir, Inchehbroon, Sofikam, and saline plains of Gharaghir, Inchehbroon, Sofikam and protected area of Inchehbroon. Species richness of different units was compared by using group regression model. Results showed that in each of two units of plain and hill, forbs were dominant. Hills in different aspects have the same plant richness and among plains, Gharaghir has less richness comparing to the other plains. In general, annuals were dominant in hills and plains and their occurrences were due to winter and spring rainfall which causes temporary top soil moisture. These plants germinate very fast and will increase plant richness.

Rangeland species preference is important due to their role in forage production estimation, that is, available forage of rangeland depends on plants preference. In this study two methods of determination of the preference value, direct time observation (DTO) and bite count (BC) in semi-steppe rangelands of Fars province was compared in 2009. In each of DTO and BC methods, 3 sheep were used to do grazing at 9 and 11 A.M and 4 P.M in four grazing periods. Time of consumption and number of bites for plant species were recorded, respectively. Data were analyzed by factorial experiment in CRD. Comparison of two methods was performed by Anova. The results showed that preference values obtained from DTO and BC for grazed species by sheep were significantly different (p<0.01).

The Necessity of fast and cheap assessment of grassland yield is evident and it is vital for it to be introduced as the best method. The aim of this research is to study the efficiency of grassland yield assessment by the Dry Weight Rank (DWR) method. This study was accomplished in Chaharbagh cold season rangeland. By way of this research, DWR was combined with the Binary Visual Estimated method and the Comparative Yield method and the two method’s efficiency compared to the Clipping and weighing method (witness) was evaluated by the T-Test analysis. The dry weight and time spent were calculated for the three combined methods of DWR and Estimation, DWR and Comparative Yield, and finally DWR and Clipping and Weighing. The difference shown between these three methods for grass life form were proved statistically insignificant. Never the less, the combined methods of DWR were not useful for some forb and shrub species.

In this research, vegetation of a part of Khabr National Park, located in Halil Rud basin, was studied. This area is approximately 18,000 hectares. 213 plant species from 47 families were identified. Vegetation types were determined based on dominant species included 9 types of Artemisia, Artemisia–Ebenus, Artemisia-Amygdalus, Ephedra, Pistacia, Pisatcio-Amygdalus, Acer-Pistacia, Juniperus-Acer, Juniperus. The vegetation types were ordination based on separation method (Bray & Curtis) and Sorenson similarity index in a two-dimensional space. It seems that ordination is affected by some environmental factors such as altitude, rainfall and slope percentage. Some vegetation types were more similar to each other in view point of ecological demands and could be placed under one management unit.

Employing a vast variety of information and complexity of analyzing thematic and spatial data، simultaneously together، are the main reasons to use Geographical Information systems to solve land allocation problems. Multi-Criteria Evaluation is a method to compromise relative importance of participating factors and to integrate the factors according to their importance in decision-making. Current research employed MCE techniques to solve one of the most important problems in natural resources management; allocating land for cultivating forage. The main hypothesis is to use MCE and AHP techniques in GIS to allocate land for cultivating forage. The Study area، Zakherd Watershed، is about 8222 ha، located in north-western part of Shiraz، Fars Province. The Research method is based on integrating AHP and MCE in GIS for location-allocation problem solving. Two Strategies of weighted linear Combination (WLC) and Ordered Weighted Averaging (OWA) selected for combining thematic maps. The results indicate WLC is a more Conservative method the OWA. However; the Overall Agreement of the Comparing the results، derived from the strategies، is about 95%، the strategy WLC is more conservative than OWA. It allocated more lands in the 2nd and 3rd classes of suitability. It allocates much more lands to the second level and the third of suitability. The results derived from the strategies have been compared to the result of ecological land suitability evaluation. It indicates that the area، ecologically suitable for cultivating forage could be classified into 3 sub-classes of land suitability، which provides watershed managers with more decision options. It seems it is a critical step to determine weight of importance of the factors than integrating method in decision-making so the cultivating limitations caused an intendancy of the results، to be same.

The aim of this study was to evaluate the results of a 5-year field study of the effects of season growth- fire on succession and vegetation changes in Zagros mountainous rangelands in Hamadan province. Burning occurred in summer-2004 and vegetation characteristics were measured for 5 years after burning every June. The effects of fire were studied by comparing plots and transects located at 6 burned sites with a nearby 6 non-burned sites (as control). Size and number of plots determined by “minimal area” and “statistical” methods، respectively. Vegetation types were determined by physiognomic-floristic method in the field. Vegetation sampling was performed based on systematic-randomized method. The measured vegetation characteristics during the study period included cover and density of shrubs، perennial and annual grasses، species diversity، forage production، litter and bare soil percentage. Forage production was measured using clipping method، Shannon-Weiner method was used for species diversity evaluation. Four transects (with a length of 50 m) were located in each of burned and unburned sites and 5 plots were put along each transect. To compare burned and unburned sites understudy properties، paired T-test was made while to compare the years changes، One Way ANOVA was used. To compare the means Duncan test was applied. Our results demonstrated that in burned sites density، cover percentage and forage production of perennial grasses significantly increased while، in contrast density and cover percentage of shrubs and annual grasses decreased. Percentage of bare soil increased in burned sites. The Species diversity reduced in initial years after burning but a gradual increase was observed at the end of study period.

Range management involves the study of rangeland ecosystem components and the interrelationships among them specially soil and vegetation. The aim of this study is to investigate the relationship between soil physical and chemical properties and a rangeland species، Artemisia aucheri. This was done at a site dominated by A. aucheri in Vavsar rangeland in Kiasar، Mazandaran. Systematic-randomized sampling was done using four transects with 100m length. In each transect samples were taken on 10 plots (2×1 m). Then cover percentage and density of A. aucheri were estimated in each plot. At 20 individuals of A. aucheri soil was sampled on four directions and three distances from plant including near basal area، canopy edge (50cm) and outside of plant canopy (80cm). Soil samples were taken from 0-15 cm and 15-30 cm depths. Soil organic carbon، total nitrogen، EC، water (%)، CaCo3 (%)، pH and soil texture were measured. Analysis of variance was done with factorial design based on completely randomized design، and then means comparison by Duncan. The relationship between cover and density of A. aucheri and soil properties were assessed using correlation and multiple regressions. Result showed that percentage of soil humidity، OC، TN، and EC significantly decreased in outside of plant canopy. Caco3 (%) and Clay (%) significantly increased with distance from plant canopy. Density of A. aucheri showed significant correlation with OC (%)، Caco3 (%) and sand while the cover significantly correlated with OC، EC، percentage of sand and silt.

The effects of managements policies i. e. grazing، enclosure، harvesting on production and plant composition of Saral rangelands located in Kurdistan''s، Iran، was investigated. Two rangelands were selected; Baharestan within which grazed and non grazed sites could be found. The second، Mangahol- Zardavan، has a harvested site and a grazed site. Samples were taken from 172 plots of 1 m2 that were established through a systematic-random design. In each plot، plant material، including aboveground biomass، standing dead، litter، and canopy of each species were measured. The comparison between inside and outside exclosure (non-grazed and grazed sites)، and between harvested site and grazed site showed that standing dead، litter and total aboveground biomass have significant difference; but there was no significant difference in aboveground live. Excluding increases standing dead، litter and total aboveground; harvest increases standing dead and total aboveground and decreases the litter. Perpetual grazing، excluding and harvesting practices have changed the vegetation composition. Grazing exclusion and harvesting significantly increased canopy cover of grasses، forbs and consequently their total canopy cover، but significantly decreases shrubs. Results also shows that palatable species were increased in harvested and grazing excluded sites.

The main goal of all ecologists is to preserve the ecosystems stability، this will not achieved unless with preservation of biodiversity. Plant communities، as primary producers، are perseveres of biodiversity in natural habitats. In conclusion for ecosystem management and biodiversity assessment in large scale، it is essential to study plant communities distribution. Current study was done in mountainous rangeland of Behrestagh of Amol in Mazandaran province. Vegetation was sampled in homogenous units with random-systematic method. To do study a total of 140 plots (1×1 m) were placed. In each homogenous unit، 1 to 3 soil samples were taken and topography properties were recorded. Using cluster analysis، the plots with the same species compositions were grouped in unit sub-association. Vegetation was separated to 9 sub-associations. The result of multivariate analysis showed that there was significant correlation between environmental factors (soil and topography) and vegetation. Soil and topography factors together accounted for 30% of vegetation changes. Also، the results showed that soil factors were more effective than topography factors in communities distribution.

Atriplex lentiformis and Nitraria schoberi potted seedlings were planted in green house in the college of natural recourses، Isfahan university of Tecnology by the end of summer of 2003. After 6 months establishment period the experiment began with 3 levels (20، 50، 80 percent) of cuttings in 2 forms as foliage and leaves in 5 consecutive harvest times. Two levels of irrigation; as normal and stressed were also applied. Plants production and performance were investigated and data were analyzed as a factorial design. Significant interaction effects indicated that: 1- Atriplex lentiformis is more tolerant to heavy grazing and is also more drought tolerant than Nitraria schoberi. 2- Productivity of both species declined after second harvest but water stress caused more rapid decline and Nitraria schoberi was more affected by moisture deficiency. Moderate harvesting in all cases resulted in higher production in each cutting and in total for both species. Second harvest had highest production in both species and production declined sharply after that in consecutive harvests. In normal moisture condition mean plant production was higher than stressed condition. Cutting foliage resulted in higher production than cutting leaves. Atriplex lentiformis had significantly higher production، higher digestible protein and better preference by sheep and goat. Sustainability، of vegetation is the most important factor in harsh environments therefore in spite of better performance of Atriplex lentiformis، both species should be planted in rehabilitation programs، since Nitraria schoberi is native of Iran and it can naturally be propagated.

In rangelands، drought and salinity are the two preventive factors for foliage production، due to their effect on seed germination and seedling emergence. In this study we evaluated the effects of salinity and drought stress on Trifolium alexandrium L. germination properties based on a completely randomized design (CRD) with four replications in water- soil and plant laboratory of Sari Natural Resource Faculty. Salinity treatments included 0، 100، 200، 300، and 400 Mm NaCl and the treatments of drought were 0، -0. 3، -o. 6، -0. 9، and -1. 2 Mpa. Salinity and drought treatments were provided from NaCl and Polyethilenglychol (PEG) 6000، respectively. Results showed that salinity and drought stress had a significant reducer effect (p<0. 05) on percentage and speed of germination، vigority index، stem and root length. Germination stopped at 300 Mm NaCl while in drought stress significant difference was observed in all understudy characteristics. Results of this study indicated that Trifolium alexanderium is a sensitive species to salinity and drought stress.

In this research the allelopathic effects of Artemisia sieberi on germination and initial growth properties of Stipa barbata was investigated. The samples wre collected from Anjedan rangeland، Arak. The study was carried out based on a completely randomized design (CRD)، including four replications and five treatments. The treatments consisted of extract of root and aerial parts of A. sieberi with 25% and 75% (W/V) concentration and control (distilled water). The results showed that extracts of root (25% and 75%) had positive effects while extracts of aerial parts showed negative effects on seed germination properties of S. barbata. The difference in root and shoot extracts effects on germination may be is due to different allelochemicals or their concentrations in mentioned tissues of A. sieberi.

Studying the interaction between range plants increase our knowledge on the ecosystem functions. The balance between competition and facilitation was studied between a semi-shrub (Artemisia Khorassanica Podl.) and a perennial grass (Bromus kopetdaghensis Drobov.) in Baharkish rangelands، Quchan، Iran. Sampling was carried out where both species were growing alone، or the perennial grass was growing under canopy of the perennial shrub. Measurements were conducted at the early growth، full vegetative or flowering stages of A. khorassanica. In the early growth season، higher soil moisture، and lower MDA and H2O2 were found for the understory than open space، indicating facilitative effects of shrub on the grass. The reverse results were found during summer times، which were interpreted as competitive interaction. The grass individuals also could affect soil moisture and physiological performances of the nurse shrub، with their effect being negative during both early and late growth season. In conclusion، results of this experiment suggest a tradeoff in the positive (facilitation) and negative (competition) interactions between A. khorassanica and B. kopetdaghensis. The type of relationship between the nurse shrub and its understory grass depends on the soil moisture availability during different times of a growth season.

Sediment yield mirrors the resultants of interaction among many different watershed components. It therefore can be studied for better understanding the governing situations on a watershed system. Annual based estimation of soil erosion and sediment yield cannot be supposed as a proper basis for designing hydraulic and watershed management structures. Estimation of suspended sediment load on storm basis is therefore necessary. Studying temporal variation of suspended sediment is an important tool for soil and water resources management of a watershed. However، the development of sediment graph under real conditions is very time and money consuming task and derivation of synthetic sedimentgraph has also been rarely considered. The present study was thus conducted in Tarbiat Modares University Forest Watershed [it needs address] with an area of 13263 ha to analyze accuracy of Time-Area Method (TAM) in sedimentgraph development. The TAM was then applied to the study watershed after providing necessary input data viz. isochrone area curve، input variables of the USLE and soil erosion routing with considering areal distribution of rainfall. The applicability of the TAM was then assessed for eight storm events occurred during October to December 2008. The results of analyses of application the TAM verified inapplicability of the model in simulating study sedimentgraphs.

Soil erosion is the most serious threat for environment، agriculture and food production in the world. It has deleterious effects on natural and human-managed ecosystems. These impacts are related to land use and management. Soil erosion starts as vegetation degraded. This study aimed to assess the effect of plant life form and cover on soil runoff and sedimentation. It was carried out in three major life forms (grasses، forbs، and shrubs) in mountainous rangelands in Savadkooh، Mazandaran province in Iran. For grasses 10 plots of 100 m2 and for other two life forms 7 plots of 100 m2 were established and then in each 100 m2 plot a number of 6 microplots (30 x 30 cm) were selected randomly. Different amount of vegetation cover was made in each microplot by clipping. These were 100%، 50% and bare ground (0%) each with two replicates. Then we applied rainfall simulator in each microplot to measure runoff volume، sediment concentration، sediment yield، runoff initiation threshold and runoff coefficient. Results showed that both life form and vegetation cover significantly influenced the amount of runoff and sedimentation. Greatest runoff was found for forbs while grasses had lowest amount of runoff. Also bare ground and 100% cover showed the greatest and least amount of runoff، respectively. The concentration of sediment for shrubs was significantly greater than grasses and in 100% cover it was significantly lower than 50% and bare ground.