فصلنامه تحقیقات مرتع و بیابان ایران
سال هفدهم شماره 2 (پیاپی 39، تابستان 1389)

Determination of forage quality is one of the fundamental factors for sound management of rangelands. Nitrogen and phosphorus fertilization of rangelands causes increasing forage quality.In this study, forage quality of Eruca sativa in three years (2004, 2005 and 2006) weremeasured in flat and northern sloppy rangelands in Maravehtapeh. In this study, 0, 50 and 100 kg N/ha and 0 and 25 kg P/ha fertilizer rates were applied. Forage quality index such as crude energy, crude protein, crude fiber, crude nitrogen and ADF (Acid Detergent Fiber) were measured in this study. Results showed that, nitrogen fertilizer increased the crude nitrogen, crude protein and crude energy and decreased the crude fiber and ADF. Phosphorus fertilization had few effects on forage quality. Nitrogen fertilization with 100 kg/ha increased forage quality.Forage quality rates increased in 2006 owing to optimum weather condition in this year. Forage quality rate is same in each flat and northern sloppy rangeland was the same. Interaction effects between two fertilizers in northern sloppy rangeland was significant.

Concepts of animal equivalent has been developed to express different kind and classes ofgrazing animal in common form. This concept is not fixed and usually determine on the basis of live weight and metabolic weight. More than 27 sheep breeds with different body size have been adapted and grazing on rangelands in different climatic zones of Iran. So it is not correct to use the same animal unit weight for all. Therefore it is necessary to determine animal unit for each breed. In this study, two herds of West Azarbayjan Makoii breed were selected, 3 and 4 years old ewes, 3 and 4 years old rams and 3 and 6 months lambs were weighted in two stages in each herd. For determination of dry matter requirement forage quality was taken into consideration.Daily requirement of animal for maintenance condition was calculated using NRC (1985) tables and MAFF (1984) equation. On the basis of results; animal unit was obtained 45.36 ± 2.75 kg which is near to animal unit weight calculated for whole country based on weight of all breeds.Daily requirement of animal was obtained 9.50 Mj metabolisable energy equal to 1.77 kg dry matter of available forage.

Dust storms are common climatic events in arid, semi arid and desert regions of the world.These events impact human resources by foundation losses, every year. Accurate prediction of these events can be effective for decision support in environmental, health, army, and other related fields. An artificial neural network is a method which can predict nonlinear problems. In this study we attempted to predict dust storms and low visibility in Zabol city using synoptic data. Result indicates that this method is somewhat successful and appears that via identification of much more dust storm occurrence process, we can do more accurate prediction.

In order to recognize, find and use applicable information in range management and forage production, surveying of ecological characteristics of Astragalus brachyodontus were carried out. The method of studying was as following. At the first step, we used a map of vegetation cover and surveyed range ecosystems to determine the habitats of this species in Ardebil province. Then, in every region, considering area and vegetation cover, we selected about six sites to study different ecological characteristics of the plant. In each of these areas, The factors related to total canopy cover, species frequency and amount of forage yield were measured.Also some qualitative characteristics such as root system, stem, seed quality, regeneration,preference value and chemical composition of the plant were studied. Results showed that this species is found between 1100 m to 2200 m above sea level in Ardabil province. Generally, the individuals of this species are distributed in mountain hills. Slopes of the habitats are 5 to 30 percent with south and south eastern aspects. Mid-term average of annual precipitation is 385 millimeters and average annual temperature is 17 degree centigrade. This species grows on soils with pH of about 7 and soils textures of sandy lome to clay lome. In terms of canopy cover, this species includes 5 to 15 percent of the vegetation. Depth of root system in soil vary form 30 to 80 centimeters. In habitats with 1500 meters elevation, vegetative growth starts in mid April. Completion of vegetative growth is in late May. Full flowering, seed ripening, and seed dissemination occurs in early June, early July, and late July, respectively. For this plant species, seed production and regeneration is relatively high in exclosure areas which are protected against grazing. In grazed areas, however, regeneration is low. Based on feeding minutes, preference value of this range plant species is very high. Considering forage digestibility and theamount of crude protein for this species, the best time to graze it is the time of flowering stage. The important pest of this species is a kind of small wasp from Eurytomidae family that feeds from the kernels of seeds and causes hollowness in them.

Flood water spreading projections have been done with many objectives. One of theseobjectives is increasing vegetation cover. Flood water spreading leads to the increasing of soil moisture and as a result increasing forage production. In this study the effects of flood spreading are evaluated. This assessment is done in aquifer of Mayhem district of Ghorveh state. In each rainfall that results into flood, 6 areas are flooded and 2 areas are not flooded. Therefore, 6 areas considered as the flood water spreading and 2 areas considered as the control site. The samplings of vegetation properties were performed in these eight areas. For this purpose, in each district, 5 transects each with a length of 100 m with 10 m interval from each other were situated and along each transect, 10 quadrates with an area of 1m2 were established. In each area, the characteristics of canopy cover percentage, forage production and species density were recorded. Analysis of data was performed using of un-paired T-test. Obtained results from Ttest indicated that there is significant difference between canopy cover percentage (p≤ 0/1) andforage production (p≤ 0/05) while no significant difference was observed for species density in flooded and non-flooded areas. The results showed that the canopy cover increased from 41/91 percent in the control site to 62/18 percent in the flood spreading area. The forage production increased from 467/17 kg/ha in the control site to 632/17 kg/ha in the flood spreading area. Also the species density increased from 1/18 in the control site to 1/59 in the flood spreading area.Some of the plant species that are in the III classes from palatability aspect, decreased in the flood spreading area rather than control site.

It is important to know soil propoerties, particulary its chemical aspects, for the propermanagement of rangeland ecosystems. The aim of this study is to find the impact of grazing on vegetation and some soil chemical properties, in three areas, the key, reference, and critical, Sisab rangelands, Bojnord. The vegetation cover data was collected from 30, 1m2 quadrats in each area through random –systematic method. The soil data was sampled from two depths 0- 15, 15-30 cm and five composite samples were collected (each sample was mixed of six samples) from each depth in the each area. Some factors such as the organic carbon, the percentage of soil organic matters, total nitrogen, absorbable phosphorus, pH and EC were measured. The results showed that carbon, nitrogen, soil organic matters, phosphorus, and EC were been decreased by grazing, but pH was increased. According to results, forbs were the dominant life form in the reference site. Shrubs cover percentages were been increased as grazing increased. In addition, reference site had species that are more palatable and invaders were more abundant in critical area. It was concluded that heavy grazing intensity cause todecrease of vegetaton and conversion of composition of the species cause to negativeconversion in alimentary mineral of soil, sustainable of ecosystem would be endangered.

Recently there is a great deal of interest in the quantitative characterization of temporal and spatial vegetation patterns with remotely sensed data for the study of earth system science. One of important methods for extracting information from satellites image is use of indices. In this study for enhancement of land cover in region of northwest Tehran near Hashtgerd some indices such as BI, MIRV2, GREENNESS, TVI, VNIR, MND، NIR, OSAVI, RA, NDVI, IR1, MSI IPV, MSAVI, SAVI, TSAVI, PD322, BI, INT1, INT2, PVI, SI1, SI2, SI3, GEMI, WDVI Are used. Most of study area covers by density of vegetation (such as irrigation farming and vegetation cover around streams) and bare lands. The results have shown that TSAVI, DVI, IPVI, RA, NIR, IR1 Indices have the most effective efficiency for vegetation enhancement and SI2, BI, TVI, PVI, INT1, SI3, SI2 indices have the most effective efficiency for salinity surface. This study addressed that all of vegetation indices except DVI have correlation more than 0. 8 and DVI has correlation around 0. 4 with others. Meanwhile all of salinity indices have more than 0. 9 correlations with each other. As conclusion, this study has shown that IRS satellites image have high accuracy for providing land cover map by use of vegetation indices, also use of salinity indices having high capability for salinity surface can be used for providing salinity maps, meanwhile vegetation indices with high correlation can be used instead each other for providing vegetation maps.

In order to study the possibility of growing four annual desert halophyte species includingKochia scoparia, Suaeda dimorphestegia, Salsola crassa and Atriplex arcuata in desertenvironments, irrigating with saline ground water, a research project comprising of threeseparate experiments was performed during three successive years, 2002-2003, 2003-2004 and 2004-2005. Field experiment carried out in a split plot design in which three levels of saline irrigation water (1.5, 9.5 and 26.0 dS/m) were arranged as main and four halophyte species as sub plots with three replications. There were high significant differences in ground covering, electrolyte leakage, dry matter accumulation and plant hight among halophyte species. Suaeda produced at least twice of dry matter as any other species at any level of salinity. The average dry matter production of this species in three years and at three levels of salinity was 11850 kg/ha, while this amount was 4725, 5136 and 3616 kg/ha for Kochia, Salsola and Atriplex, respectively. Ratio of leaf to shoot weight was varying from 39% in Atriplex to 56% in at full flowering stage. In conclusion, germination and plant stablishment of these four annual halophytes should be explored for domestication. High dry matter production of these species in watering with saline waters of more than 70% of seawater, make them capable for production invery high saline lands, as well as irrigation with high saline waters.

The study of plant diversity dynamic on grazed and enclosed rangelands is important inrange management. The effect of enclosure was studied on plants diversity dynamics on two ange condition sites of Dishmook area in Kohgiluyeh & Buyer Ahmad province. Randomsystematic ampling was done in two range sites using 220 (2×2 m2) quadrates along 6 transects ith the length of 100 m. Vegetation canopy cover percentage was recorded simultaneously in oth range sites. Diversity, richness and evenness were determined by using plant diversity ndices (Shannon, Simpson, Berger parker & Mc intash). Results show a higher species ichness, evenness and species diversity indices in enclosed rangeland. Statistical T-Student Test showed significant differences between two sites in 5 percent level of probability

This research was studied in order to determining grazing intensity effects on soil moistureand vegetation in Khabr region of Kerman province for two years. Natural sites under three grazing pressures (heavy, moderate and non grazed) with same ecological factors were selected from Khabr National Park and near rangelands. After determining sampling area, soil moisture factor was investigated monthly (on grazing period) in 0-15 and 15-30 centimeters depth of each site with 5 replication and canopy cover sampling was conducted in three temporal stages (before, middle and after grazing) using line transect method in three replication for each site. SPSS package was used for statistical analysis. Result showed that heavy grazing reduced total canopy cover, specialy perennial grass and shrubs, than non grazed site in the end of grazing period. Also heavy grazing reduced the soil moisture content with decreasing rate as 16.87% and 25.07%, than moderate and non grazed sites, respectively. Harmful effect of drought in 2006 was severly affected on heavy than moderate and non grazed site. According to results, non and moderate grazed sites occure in state condition (due to more canopy cover of Artemisiasieberi and other species such as prennial grass) and heavy grazed site occure in transition to downward state condition (due to one dimentional dominant of Artemisia sieberi andemergence of undesirable species such as Marrobium vulgaris and Peganum harmala) in state and transition model of Iranian Artemisia habitat. Thus, without management plan, we will observe dominance of undesirable species and rangelands degradation.

Growth of plants species in an area is affected by biological and environmental factors ofthat region. It is necessary to study some ecological requirements of species and alsoenvironmental characteristics of the study area in order to determine site potential and plant growth needs. this study performed to determine potential habitat of Haloxylon persicum and Haloxylon aphyllum in Sistan province by using Geographic Information System (GIS) technique. In this way sampling from habitats carried out for recognition of ecological requirements. Also thematic maps of area provided and digitized for attainment data layers which were needed. Then various sections of area were investigated and were compared with ecological requirements of these two species. Finally, the different layers of information were put together for every species. Base on our results, 3.18% and 3.52% of the studied area was suitable for growing H. persicum and H. aphyllum respectively. Assessment of accuracy of model was 93.3%.

Prangos ferulacea (L.) Lindly as one of the best Iran`s range plants, is the dominant species of Iranian Jashirzar. Competitive harvesting, lack of attention to vegetative conditions and their habitats caused a disturbance on its reproduction and also the degradation of its habitats. Since the regeneration of the plant is only done in the natural habitats and through its seeds _when having in mind its deep dormancy as a member of umbelliferae family, it seems necessary to study and investigate the methods of breaking the seeds dormancy in order to protect the species. In this research in order to determine the best methods of the breakage of the seeds dormancy, the effect of some factors such as darkness, lightening, coldness, washing and temperature on the breakage of the dormancy of Prangos seeds_ collected from Fars Province pastures _is analyzed. For this purpose, a completely randomized design with three replications and five treatments was done. The results showed that treatments of coldness, lightening and 10°C temperature in compare to other treatments have significantly influenced the breakage of the specie's seed dormancy. Meanwhile these methods are more important when we remind that, they are more economical and safe for the embryo in compare to other treatments such as using chemicals (specially acids). All of these together make these treatments practical methods.