فصلنامه تحقیقات مرتع و بیابان ایران
سال شانزدهم شماره 2 (پیاپی 35، تابستان1388)

Fall planting of forage legumes normally is not successful in central Zagross mountain region because of possibility of germination after autumn rainfall and mortality of seedling by early frost during fall season. For planting legumes in the spring there are limitations since seed planted after early spring rainfalls cannot be successfully established. During early spring rainfall period high soil moisture does not allow planting operations. Therefore government projects for rehabilitation of abandoned dry farming lands can not use seeds of forage legumes such as Medicago sativa (Me. sa), Onobrychis viciaefolia (On. vi) and Vicia villosa (Vi. vi) with good quality forage and proper yield with high adaptability to soil and environmental conditions of the region. To solve the problem، this research was conducted to evaluate the effect of seed treatments with germination inhibitors and hydrophobic materials as well as seed pelleting in Shahid Fozveh research station in germinators and green house. Caffeine, vanillin and extract of Eucalyptus leaves were used as inhibitors. Poly ethylene glycol 6000 (PEG) and Di- manitol (DM) were used as hydrophobic substances. Seed pelleting was achieved by using a coating drum device. Treated seeds were put in germinator with 25ºС constant temperature. Velocity coefficient of germination, percent germination, germination commencement delay and alometric ratio were determined. Data were analyzed as complete random design and Duncan’s test was used to determine significant differences. Results indicated that vanillin caused 18 and 14 days germination delay for Me. sa and Vi. vi respectively. Vanillin and extract of Eucalyptus leaves delayed germination of On. vi unshelled seeds for 21 and 22 days respectively and proved to be best materials for this purpose. Caffeine reduced germination percentage of all seeds. PEG and DM delayed germination only for 3 to 7 days, not long enough to be useful for practical purposes. Pelleted seeds without inhibitors and hydrophobes showed 9 to13 days germination delay. Pelleting along vanillin treatment caused 20 and 16 days delay in germination of Me. sa and Vi. vi respectively. Pelleted unshelled seeds of On. vi treated with vanillin and extract of Eucalyptus leaves had germination delays for 26 and 22 days respectively. With rapid decrease of temperature during fall season in central Zagross region it seems reasonable to consider a delay of more than 15 days to be practically effective to reduce or eliminate mid fall germination of these species and increase success of fall seeding considerably. Further investigations with field planting is recommended.

Range management needs to accessing data by fast and suitable methods for planning. Satellite data and geographic information systems (GIS) can be used for planning and integrating field and remotely sensed data. Landuse map is one of the most important information in range management plans. This requires overlaying, retrieve and analysis detailed information about the rangelands in GIS. Land use map provided using Landsat7 ETM data (15 Apr. 2004) for the study area (middle catchment’s of Taleghan) in the Tehran province. Based on histogram of bands and statistical analysis, bands 4, 3, 2 were selected for color composite in unsupervised classification method. We identified 4 classes land use type of study area in the fieldwork. Ground data was collected using systematic with random start point, from 86 plots (250*250m), using unsupervised map as a primary map. Overall, with combining the ETM data and the field data using supervised classification method, boundary of the landuse types were put in four classes (Rangeland, Farm land, Dry farming and Bare soil). The classification accuracy assessment showed that the overall accuracy 70.64 percent and accuracy rates of the rangeland, farm land, rain fed carping and bare soil were 81, 54, 61, and 81 percent, respectively. So it is possible to use Landsat 7 ETM+ data for landuse mapping which is essential in range management and range suitability classification.

In the present paper, trends of rainfall, runoff and temperature in the Kordan sub-basin which is one of the sub-basins of Qazvin basin were investigated for period of 1966-95. This sub-basin with 360 km2 area is located in the north eastern part of Qazvin basin with a different range of elevation from 1410m to 4108m. Results show although there is not any change in the trend of annual rainfall, but a significant increase and decrease in total amount of precipitation in the second half of year (cold months) and in the first half of year (warm months) and increase in the monthly temperature in most of months were observed. Also trend of moving average of ratio runoff/rainfall (coefficient of runoff) shows significantly a sharp increase annually and also for seasons of spring and autumn. A comparison for coefficient of runoff between first and third decade of period shows different amounts of increase annually and also for seasons of spring and autumn as 58.9%, 12.9% and 5.1% respectively. Increasing of coefficient of runoff in spring is related to general increase of temperature and also precipitation increase in winter season. Increasing of coefficient of runoff in autumn is related to precipitation increase in this season and also occurrence of mismanagement in plant, soil and water resources. Therefore the volume of runoff in this sub-basin which is evacuated and wasted more than before, reaches to 9.4 million m3 per year.

30% of lands earth are considered as arid ecosystems with around 44.7 mil km2. About 39% of the latter with an area of 17.4 mil km2 are considered as semi-arid regions. Around 90% of semi-arid area are located in 27 countries which has a 20% population of the world. About 86% of Iran area is considered as dry areas which greatly affect the various functions of human population. Delicate conditions of ecosystems and human invasion to natural resources in these areas has provided a national warning. Analysis of historical situation would provide a good stance to monitor the desertification condition in these areas. In this study we have tried to compare the historical situation with present condition and analyze the desertification trend. Our results showed that 76.7% of Khorasan province area are impacted by various desertification mechanisms. Our analysis revealed that desertification of vegetation cover together with water and wind erosion (first order process) with 44.7 percent of the area are the dominant factor. Water and wind erosion together with vegetation cover destruction in 24.3 percent of the area is the second order process and finally salinization is the third order process.. In terms of desertification order, 36.6% are under extreme desertification impact, very hard, medium, and delicate are with 14.4, 13.1 and 12.6% accoridingly.

In this research, first of all the key and important species as well as associated species of rangelands were recognized, then morphological and seasonal changes and preference value were determined on the selected species such as Artemisia aucheri, Kochia prostrata, Bromus tomentellus, Asperula glomerata and Buffonia cf.koelzii. In this research phonological stages of plants divided into 3 main stages including vegetative, flowering and seed maturity. Species preference values were studied with the method of time measurement. Effective factors on species palatability such as morphological characteristics, phonology, and chemical factors (Carbohydrates, Hemi cellulose, Protein…) of the species also were investigated. In the final step, data obtained in measurement time method were compared with environmental and morphological characteristics of the species as well as forage quality. The palatable species such as Bromus tomentellus, Asperula glomerata, Buffonia cf.koelzii and annual grasses were severally grazed in early time of the season. Rate of the grazing of, the species As. glomerata, Bu. cf.koelzii, Br. tomentellus and Ar.aucheri were 56, 59, 74 and 43 percent respectively. The laboratory analysis of forage quality also showed that there are positive correlation between moisture, protein and soluble sugar percentage with rate of forage use percentage. The regression equation showed that the amount of humidity, protein and soluble sugar with 56, 21 and 10 percent respectively shared in this model and high correlation of these factors showed their important role.

Accessibility to a major portion of basic information about vegetation function of rangeland ecosystems is provided via autecologcal study of range plant species. These information are required for proper management of related rangelands. This research was conducted to examine the autecology of Cenchrus ciliaris in Khuzestan Province of Iran. Some topographic, climatic, and edaphic characteristics, as well as the boundaries of its natural habitats were determined. Also, the phenological stages of the plant were observed. Results showed that the habitats of this plant species are mainly located in south western and south eastern sections of the province, with east and south topographic aspects and altitudes ranging from 60 to 420 meters above sea level. This range plant generally grow on sandy loamy soils of the province. The soils of these habitats are slightly to moderately accompanied with debris and sandstones. Average annual precipitation at its habitats is 233-341 millimeters. Fall vegetative growth of this species began earlier than accompanied native species.

The superabsorbent polymers absorb and retain large quantities of water when applied into the soil. This capability is due to its physical and chemical properties. The objectives of this study were to investigate the effects of soil salts on polymer and manure water uptake ability under repeated wetting and drying cycles. The results showed that 1.0 g polyacrylamide made of Iran, had ability to uptake 184.4g distilled water for the first time absorption. It was much less than the same material that had reported in foreign publications. The ability of water retaining for the same polymers was dramatically decreased to 31, 79 and 83 percent than control treatment(distilled water) for waters with 160, 1000 and 2000 mg/l salt concentration, respectively. By 9 times repeated wetting and drying cycles, the ability of polymer had decreased to 22 percent of the first times absorption. As consequently, the amounts of water uptake had also decrease to 72, 81 and 88 percent of distilled water in the same salts after 9 times repeated wetting and drying cycles. At the hottest times of the summer, drying of poly acryl amide super absorbent had take 6 and 2.3 days for distilled and salty water, respectively. The results showed that the negative effects of Na+ were less than those for Ca2+ and Mg2+ on polymer water absorption. For completely decayed animal manure, the retaining of distilled water was 2.3g for 1g dry manure. For water having 4000 mg/l salts concentrations, the uptake ability of manure was not significantly different than distilled water. The drying period of manure had taken the 17 and 18 days for distilled and salty water, respectively.

Regeneration of black saxual (Haloxylon aphyllum) is an important project for sand dune fixation in desert area of Iran. Success of this project is largely depending on climate conditions and soil physical properties. In order to determine some inhibitor factors of black saxual growth, a project were conducted in a 2 ha black saxual site in Semnan, Iran. Morphological traits as: plant height, canopy cover, collar diameter and collar first sympodial interval and growth index were recorded on 5 year old shrubs. At the mean time soil properties as: EC, pH, SP and Texture (silt, clay, sand), were measured. The relationships among plant growth indices and soil properties showed a negative correlation (P0.05) between growth index and saturation percent (SP). It was concluded that SP factor was the most important factor to inhibit black saxual growth in Semnan province, Iran.

The major part of Qom province areas have involved arid and desert conditions. Immethodical expansion of human acts with no attention to environmental affairs, caused intensifying desertification phenomena. In this paper, trend of desertification was studied with emphasis on land use changes and as well as water quality and quantity resources. For assessment land use changes, satellite data (TM, 1985 and ETM+, 2002) and for evaluation of water quality and quantity resources changes, the hydrometric and climatic data were used. Comparison between land use maps of TM and ETM+, by using visual interpretation method, showed that areas of agriculture lands, rangelands, forest lands, sand dunes and salt lakes, have been decreased in 6.5, 4.14, 70.4, 24.2 and 15.8 percent respectively, whereas, another classes such as saline lands, urban and rural lands have been increased 26.6, 12.78 and 35.6 percent respectively. The output water of 2 main rivers of Qom province (Qomroud and Qarehchay) before establishment of Panzdah-e- Khordad and Saveh dams were 261 million m3, whereas it decreased to 66 million m3 after obstacle foundation. Before construction of Panzdah-e- Khordad dams, The fall of underground water level was 0.5 meter per year in Qom plain, which increased in averages to 1.4 meter per year after establishment of the dam. In addition, balance sheet of underground water, reduced remarkable. Totally, it seems that the human activities and retouching environment by him (especially construction of 2 dams on Qom rivers) are two main factors which have changed (with decreasing plant covering, salinization of major areas et cetera) and reduction of quality and quantity of water resources which could lead to aggravation of desertification in Qom province.

Recognition of the autecology of plants and understanding their importance in soil protection, as well as forage production for livestock, is a proper strategy for management, conservation, and development of renewable natural resources, specially vegetation. This investigation was carried out on autecology of Stipagrostis pennata in Yazd province. For this plant, ecological characteristics such as geographic distribution, climatic properties, topography, and soil were studied. Also phenology and root system of the plant were examined. For this purpose, three study sites of Mansoorieh (in Tabas area), Masjed-e-shokr (beside Yazd-Tabas high way), and Bafgh were determined. The results showed that Stipagrostis pennata is a psammophyte plant with standing stems and branches. This plant grows in low-height sand dunes and sandy hills. Elevation range for areas in which this plant grows is 700-1600 meters above sea level. Measure of soil acidity (pH) is 8.25-8.53 and electrical conductivity (EC) is 0.48 to 1.2 ds. This species starts its vegetative growth at the end of February and flowers in early May. Its seeds ripen in mid June. During summer and autumn, the plant is in dormancy stage. Due to high aerial organs, Stipagrostis pennata has a good resistance against sandy storms and winds. So it is highly recommended for mobile sand dune stabilization and control of soil erosion in desert areas. It also produces a fairly good amount of forage for livestock and wildlife.

Salinity is one of the increasing problems in the world which include the wide area of our country. Regardness to increment in salinity lands and shortage in desirable soils for cultivation, recognition of range plants that are salt tolerance is very important. In order to study the effect of different salinity levels on germination of Haloxylon phyllum, Seidlitzia rosmarinus, Haloxylon persicum, Pteropyrom aucheri, Zygophllum euryypterm, Sueda fruticosa, and Atriplex lentiformis species, the experiment was conducted in germination stage as a factorial experimental based on CRD with three replications. Salinity levels applied were zero (control), 100, 200, 300, 400 and 500 mM NaCl. The results showed that with increasing salinity level, germination rate and percentage of germination were decreased. This decrease was different among the studied species. There was very significant difference between levels of salinity. Among the studied species, Haloxylon aphyllum and Sueda fruticosa had the maximum and minimum percentage of germination respectively. Seidlitzia rosmarinus and Pterophyrum aucheri had the maximum and minimum of germination rate respectively. Ability of germination in different concentrations of salinity describes rate of seeds resistance. There was very diversity for germination responses of the studied species.

The present study firstly sets out the procedure for the generation of climatic files for localities with climatic records and secondly, The process of obtaining maps of the climatic zones for all of the localities in the Salt Lake Basin of Iran. For the generation of the climatic records such as rainfall periods and intensity, provided by the 34 climatology stations for a total of 44 years data from (1957-2000), was used as a source of information. These data was then subjected to a statistical analysis, using SPI method for the calculation of the frequency, intensity and duration of drought process. Finally for the mapping drought zoning in all localities of the Salt Lake Basin for the long term period, the Inverse Distance Weighted Method(IDV) was used in the Arc view software environment. The results showed that the study area is very sensitive to climatic drought.