فصلنامه تحقیقات مرتع و بیابان ایران
سال چهاردهم شماره 2 (پیاپی 27، تابستان 1386)

One of the halophyte plant species in the rangelands of Golestan Province is Halocnemum strobilaceum which grows in areas of saline and alkaline soils with shallow water table. It belongs to Chenopodiaceae family. It is named Cheraton by local people and covers 167,000 hectare of the province area. Five study sites which are named Gomishan, Sangar-tapeh, Soficom, Incheh-shoreh-zar, and Incheh-boroon were selected to conduct the study. A formula of L = 2D + d was used to calculate a proper size of measuring plots. Letter D represents the diameter of plant and letter d represents the distance between individual plants. For each site, three transects and thirty plots were used to measure canopy cover, density, frequency, and the proportion of this species in plant composition. Also the weight of above-ground production and roots were measured. The size of plots in Gomishan, Sangar-tapeh, Soficom, Incheh-shoreh-zar, and Incheh-boroon were 1, 2, 2, 2, 4 square meters, respectively. The results showed that, in terms of canopy cover, density, regeneration, above-ground production, and root production of this range plant, there are significant differences among different sites. This plant showed the most (%26) and the list (%6.46) canopy cover in Gomishan and Incheh-boroon study sites, respectively. It also showed the most (59300/ha) and the list (5250/ha) density in Gomishan and Incheh-boroon study sites, respectively. The frequency of plant was %86.6 to %96.6 in different sites. The plant formed %50.93 to %65.53 of the plant composition in different study sites. The most above-ground and root production were found in Incheh-boroon area.

Desertification is the ecologic and biologic reduction which may occur naturally or non naturally. Desertification process usually effects arid and semi arid region and reduce the land efficiency very rapidly. This study has been conducted to evaluate and classify desertification with the aim of geographic information system and remote sensing techniques. In this study, TM data of 25 shahriver 1369(16 October 1990) and ETM+ data of 16 shahrivar 1380 (7 October 2001) were used. Geometric, radiometric and sun height angle correction were carried out on the images. Supervised and unsupervised classification were used for both two images and 9 land uses were classified and compare quantitatively due to geomorphology and desertification attributes. Each main and partial desertification factor was input to geographic information database and scaled to make the map of desertification severity based on recommended method for Iran and FAO map of desertification vulnerability. The result of desertification severity which shows desertification condition, velocity and potentiality, showed that natural desertification occurs in 35 % of area with different medium, high and very high desertification severity. Anthropogenic desertification includes 65 % of study area with high and very high condition. But in desertification vulnerability map, very high desertification vulnerability was determined in 20 % of area with simultaneous human and animal effect and high desertification vulnerability was determined on 80 % area with only animal effect. According to the map, for arid region of north of isfahan, it was identified that range land use change to agriculture, improve agricultural patterns, over grazing, incident economic condition and ground water over exploitation are the most important anthropogenic factor, and drought and soil and water salinity are the most important natural factors. Desertification trend is enhancing to north west of the study area which will make trouble for rangelands, residential and industrial areas.

A vacuum system was designed for harvesting rangeland and grass seeds from the soil surface or the plant canopy including vacuum harvester head, thresher and cleaner units. System design was based on physical characteristics, mechanical and aerodynamic properties of Annual medics. This combine is designed as a full or half –mechanized seed harvester suitable for even and uneven ground levels. To work on uneven ground, the head is easily detached and seeds can be harvested using hoods operated by one or two workers. Combine design is so that with suitable adjustment is able to harvest many kinds of rangeland seeds. Suction capacity was 312 kg/ha for seeds having 40 % purity and 750 kg/ha at 60 % purity. Efficiency of the cleaning sieves and the air separator were 67 5 and 80 % respectively. Threshing efficiency on various thresher speeds was 75 % up to 90 %. System power requirement is 1.07 KW provided by tractor PTO shaft through a belt-drive system.

Remotely sensed data are able to monitor some characteristics of the environment and also their spatial structure. The latter one is the first and main step in field data interpolations. Therefore, spatial analysis of some field data is possible by employing of related satellite data bands. In this study, as an example, Landsat ETM+ thermal band (band 6) was acquired to determine the spatial structure of surface temperature distribution. For the purpose of evaluation and selection of the best interpolation model, the band 6 data was crossed with a regular sampling grid and therefore, a dataset was constructed. Using geo-statistical analysis, empirical semi-variogram was calculated and various mathematical models were fitted to its points (e.g. gaussian, exponential, circular and spherical). Afterwards, the fitted models were applied to generate different temperature distribution maps using kriging interpolation approach. Finally, the optimum model which could better predict temperature changes and distribution was recognized. Result of the study shows that the exponential model would be better to predict and estimate surface temperature in un-sampled locations in the area of studied. So, the model can be used for interpolation of field temperature data with a high confidence level. The represented method can be developed for all the other environmental factors which could better characterized by remotely sensed data, like minimum and maximum temperature, evapotranspiration and so on.

Autecology's studies on plant are conducted to investigate about the relationships between a particular plant and other components of ecosystem. Ecological knowledge about range plant species are essential for rehabilitation, and management of rangelands. This study was accomplished to provide information about ecological characteristics of range plant of prangos ferulacea from 2001-2004 in Kurdistan Province. In the survey, some topographic, climatic and edaphically aspects, as well as boundaries of the ecological habitats of this species were delineated. Phonological stages, root system, crown cover, density, reproduction, adequate depth for seed planting, preference value of this plant were evaluated. The results showed habitats from view point of crown cover not significant difference at ά ≤ 0.05, but from aspect of density and regeneration were significant difference between of them at ά ≤ 0.05 & 0.01. The highest average of plant density achieved in Daraki 16.7 in 4 square meter and lowest density in Ariz 6.5 plant in 4 square meters. The Daraki habitat’s from aspect of plant regeneration with 13.3 plants in 4 square meters was better than the other, and Shian has the lowest regeneration (3.1 plant). Phonological stages showed that this plant has a short period of growth and starts in April and continues still early August. Soil texture and soil depth were affected on root grow and development. In Khan and Ariz habitats, penetration of root were 140 & 177.5 centimeters, whereas this parameter measured in Shian and Daraki 146.7 & 77.75 centimeters, sufficient depth for seeding Prangos ferulacea was 4 centimeter. Average of thousand Seed weight 212 gram was measured. Plant mostly grows at 500 mm. rainfall, 1700-2300m.above sea level and northern slopes in Kurdistan. Test of soil texture indicates that this plant grows in different soils, especially clay soil texture. Finally this plant has an important role in rangelands by having forage production and soil conservation.

Understanding the relation between the plants,The environmental factors and the other living creatures is a necessary problem in preserving the constancy in all eco-systems.Man in order to cope his needs, has used the natural resources and during thousands of years using the eco-system had been effective in changing them. In this research having the vegetation map of this area which had been provided by Macgoven Australian co,The map of plant type in 1372 using G.I.S has been provided and the changes in plant cover during this period were evaluated. Comparing the two maps,The result was that among the 20 recognized types in 1352, 3 types because of grazing and other factors have been completely wiped out, and the other types have been changed into newer types or there are some changes in the variance of some other types. In plant coverage studying, in order to specify the range condition trend,the methods of: 1) Four factorial metuod. 2) clipping and weighing method. 3)trend method were used. Using Trend method and comparing the plant cover condition in 1352 and 1372, we came to the result that there is no positive trend in any types. In 8 types, the trends are constant and in 9, the negative trends have been reported. In order to explain the 17 trends in 1372,the map of range condition trend in G.I.S system has been drawn.

Wind erosion is one of the major problems in arid and semiarid regions, where the erosion and sand transport caused by wind can lead to serious problems for civilians live in those areas. The regions under wind erosion, includes the sources, transition and deposition areas. Amongst them, identification of the sources areas is significantly important, which affects our investigations, evaluation and control over wind erosion. It has been found that the application of Remote Sensing (RS) techniques and Geographical Information Systems (GIS) is considerably useful to find the sources of sand in wind erosion. In this study, a combination method based on Image Processing and Wind Analysis (IPWA) has been introduced and used to identify the sources of deposited sand in areas under wind erosion. The method is based on utilizing and composing of image processing techniques such as image enhancement, threshold, false color composition, filtering, and Spectral Profile Testing and Analysis. The results are compared with other investigations to validate the method. It was observed that the results of the present method are well comparable with those of previous researches which are highly based on field investigations. Without extensive field measurements, the method reduces the time and the cost of investigation and provides a basis for repeating the operation at any time and everywhere, which is required.

Whereas more than 90 % of Iran is located in arid and semi-arid area, water is one of the most important factors that can prevent from sustainable development in all of agricultural subjects. Thus, the water can play an important role in ecological condition changes especially for plants. In this research, it was attempted to survey the water harvesting and its spreading impact on plant composition changes in a flood spreader. The study area is located in the part of the Zanjan plain, in north-west of Zanjan city and between two rivers Sorhain and Qarecharian, which is include rain fed and released lands that, has been occupied by quaternary deposition. For this purpose, the amount of rainfall and diverted floodwater to the station monitored and measured during all flooding time. In order to evaluate the plant composition changes in three sites in spreading area and one in control site, totally 11 permanent transects (9 in spreading area and 2 as control) were stabilized and using Line Intercept Method, the canopy cover percentage of all species were noted and all species were distinguished. This study showed that some species under impact of floodwater spreading omitted, some increased or decreased, and some new species observed for first time. Increasing of the vegetation cover and appearance of palatable plants in last year showed that the floodwater spreading can improve the foliage production. Considering to life form of observed species, although perennial forbs increased, but the floodwater spreading in the case of establishment of perennial grasses did not operate successfully. Therefore, shortage of studying period (8 Years) and changes on amount of harvested floodwater make correctitude of these obtained results rather less valid.

In this research, to identify the functioning of the soil-landscape system and its effects on plant growth for native rangeland, we investigated the relationships between soil properties and Landscape Function Analysis (LFA) indices and between plant growth characteristics and LFA indices. The results interpreted based on statistical analysis and expert knowledge. This research was carried out for a semi-arid rangeland in the Lar aquifer in Iran. Land stratification allowed the study area to be subdivided into Land Units, according to specified criteria including landform attributes (slope, aspect, and altitude), and vegetation type. A factorial model on the basis of a completely randomized design was used to analyze the data collected from 236 land units. The landscape function indices including nutrient cycling index, Infiltration index, Stability index, and Landscape organization index were derived by various integrations of soil surface attributes. Landscape attributes differed from one another in their effects on the different landscape function indices. Increasing slope gradient significantly reduced all landscape function indices as well as soil organic carbon and total nitrogen percentages. Slope class exhibited highly significant interaction effects with vegetation type factors for stability, nutrient cycling, and landscape organization indices. Aspect did not significantly affect stability, infiltration, and landscape organization indices, but significantly affected the nutrient cycling index. The Duncan test indicated that north aspect (shady side) had the highest mean value (28.42) and south aspect the lowest mean value (25.57) for nutrient cycling index. These results are consistent with the effects of aspect on total soil nitrogen and soil organic carbon percentage for which the north aspect had the highest values. The values declined in the sequence east, west, and south aspects respectively. This research indicates that the nature of native rangeland plant communities and their measures of production are closely related to nutrient cycling index.

The effects of climatic factors on four dominant range land species of Markazi province, Iran, were studied. Species were Artemisia sieberi, Salsola rigida, Noaea mucronata, Stipa barbata and were monitored from 1998 to 2005. Site is located in steppe lands and called Nemati range, Akhtarabad of Saveh. Climatic factors were annual rainfall, rainfall of grazing season plus rainfall of previous year, temperature, solar radiation and wind velocity. Among the main indicators, as results shows, growing season plus previous rainfalls is the most effective indicator on forage production with high and significant correlation. Total yield have positive and significant correlation with growing season rainfall and previous rainfall as well as production of Artemisia sieberi, Salsola rigida. Soil and water regime in dry and semi-dry areas, in growing season, is in a way that plants are dependent on stored moisture. Shrubs, with their deep roots, are more capable of using this moisture. Therefore stored moisture could be known as an indicator of rain quantity. Result of this research showed that rainfall indicator in growing season and previous season is a variable that plays fundamental rule in production, showing a linear relationship. Negative correlation was shown between number of sunny days, total yield and yield of two species, Salsola rigida and Artemisia sieberi.

Composing multi criteria and factors and do right decision making in rangelands for Biological soil Erosion Control is very complicate and strongly need to apply computer and spatial decision support systems. With these and experience a decision maker can show the best solution fast. Hable Roud watershed had many spatial data that provided by companies and organizations. Rangelands in this watershed were selected. A model for compositing the natural suitable spatial factors (sediment discharge, slope, rainfall, Range Factors: animal unit month, range trend, range condition), economic (proximity to road, proximity to villages, proximity to rivers, proximity to wells, proximity to spring) and constraints (slope, land use, village, roads, rivers, and rainfall shortage) was designed for suitable biological soil erosion control planning. Then they were standardized in value range between 0 & 1. they were weighted by analytical hierarchical processing (AHP). Of course some cases were weighted by direct method. Compositing of these layers were done by spatial multi criteria evaluation (SMCE). Output was composite index map. This map was classified by its histogram, and identified in each class which measure should be done. Biological soil erosion control plan was recommended (manure spreading, seeding with manure spreading, seedling and enclosure).

Of the many Climatic events that influence earth’s environmental fabric‚ drought is perhaps the one that is most linked with desertification(WMO‚1997).This Investigation is an effort for assessment of acceptability about many of Climatic current Drought Indices in reagent and sample stations of Salt Lake Basin of Iran. These drought indices which are used in world active systems, are Percent of normal precipitation Index PNI, Deciles of precipitation Index DPI, Standardized precipitation Index SPI, and Z Score Index ZSI.The above mentioned indices were calculated first by average of monthly precipitation data for a 44 years period from 1957 to 2000 relate to 34 synoptic and climatological stations in their common time scales. Based on obtained results from one hypotheses, DPI and SPI indices in the contemporary with minimum occurrence, showed, extremely drought in the studied stations. These acceptability of indices in more than of other indices and according of this investigation,DPI index sit on the first place, SPI sit on the second place, ZSI index sit on the third place, and finally PNI Index, sit on the forth place. In next stage the Standardized Precipitation Index SPI, based on precipitation values from 34 monitoring stations around the Salt Lake Basin of Iran, is computed monthly and was performanced for climatic interpret and characteristic include assess drought relative frequency, intensity, expand and duration and calculated return period of the most intense drought and according to the point stations data, drew intense map. This investigation indicate the most intense drought in Salt Lake Basin of Iran belong to Hamadan(Nozheh) and the longest drought duration in Avaj ‚Dooshantappeh‚ and Kashan Stations with the highest relative frequency digit of drought (38/6%) and the lowest relative frequency digit of drought (18/1%) belong to Golpayegan. The most of severe year has occurred in 1973 and 1967 in 44 years period.