نشریه خشک بوم
سال سوم شماره 1 (بهار و تابستان 1392)

Finding an appropriate land to implement an activity in a particular geographical region became a significant phase of project implementation process especially in regional and national levels. One of the most useful tools in finding the susceptive locations of desert revival is utilization of computerized models. Finding the locations using Fuzzy Logic and Geographical Information Systems has been utilized in various special fields. This research aimed to determine the appropriate locations of desert revival with the risk degree by using of this model. This research adopted a method based on inspecting and grouping of environmental parameters affecti on preventing desertification. The method is accomplished using available parameters in the region and mapping of these resources were done by using Kriging and IDW methods; and ultimately specifying a simple model by valuation of Fuzzy Logic. Results showed that the Fuzzy model Gamma 0.8 had the best compatibility for recognizing the deserts and the susceptive places for combating desertification with high success rate or desert revival risk.

Management of animal nutrient and stocking rates depend on nutritive value and nutrition requirements of grazing animal. Determination of nutritional value of forages is one of the necessary factors in grazing capacity. In this study، seven plant species including Seidlitzia rosmarinus، Stipagrostis pennata، Salsola richteri، Halathamnus glaucus، Astragalus squarasus، Salsola arbuscula and Reaumuria fruticosa as considerable components of rangelands vegetation in the region، were collected during three phonological stages (vegetative growth، flowering and seeding stage) in 2008. Then، forage quality index including Crude Protein، Acid Detergent Fiber، Dry Matter Digestible and Metabolism Energy were determined and compared with their critical levels. In order to data analysis، split plot statistical method with randomized complete design in 3 replication of 21 treatments for each location، was used. In order to find the sources of variations within groups، Duncan test was employed. Results showed that mean crude protein amounts at vegetative growth and flowering stages are higher and at seeding stage are lower than its approximate amount of critical level (7%) for supply the daily requirement of animal unit. Mean amounts of digestibility at different growth stages are higher at all phonological stages than its critical level (50%) for one animal unit maintenance. Metabolism energy amounts at vegetative growth and flowering stages are higher and at seeding stage are lower than its approximate amount of critical level (8 Mj) for supply daily requirement of animal unit. Results also showed that، in active growth and flowering stages، forage contain metabolism energy، crude protein and dray matter digestibility، were more than critical levels. Which provied، daily requirement of grazing livestock in maintenance provide. But in maturing stage، their values were low than critical levels and daily requirement of grazing livestock can not be provided. Therefore، live animal weight and economical performance will reduce. So it is recommended that according to range condition and costs، of feed schematization and nutrition supplements are used for reaching animal favorite performance.

This study aimed to investigate the Baluchi camel age and the kind of plant species on preferences of plants for grazing by the Baluchi camel in Zarrindasht، south of Fars province. For the evaluation of preference values، firstly plant communities were distinguished and 10 plots 2m × 2m were then established in each community in the key areas. Cover percentage of each plant species was visually estimated in each plot. Preference indices (for 5، 10 and 20 years old camels) were estimated for the all plant species through direct time observation method. Factorial design was used to determine the effect of Baluchi camels age، plant species and their interactions on preference value. In the case of the significant interaction between plant species and camel age، for determining the camel age and plant species effect on preference value of plants، one-way ANOVA and Duncan test were performed. The results showed that Ziziphus spina-christ،Tamarix aphyllaandSeidlitzia rosmarinus had the highest preference value for all three camel ages and the lowest values were related to spiny species of pycnocycla spinosa andRhamnus alaternus. In general، hort trees were more preferable than shrub species for camel. Oldest camels (20 years old) consumed highest time for browsing. The results of this study revealed that it is necessary to have different strategies to manage the grazing of different camel ages. Since Ziziphus spina-christ is being browsed by all three different ages، it is suggested that management activities plan preserving and restoring this species.

In our country، agriculture has been introduced as independence and sustainable development driven. So، special attention should be paid it. Growing population and increasing need for natural resources has caused to reduction soil erosion and sustainable agricultural development have became considered issues in recent decades. Water and soil are two essential inputs in agricultural production. In this Study، two methods including contingent valuation and experimental choice were used to valuation the area. The required data was collected by filling 121 questionnaires by the area citizen who were chosen randomly. Then conditional logit model was estimated. The results indicated that total social values temporary were 0. 518 to 1. 546 Milliard Tomans and per acre almost are 14000 to 41000 Tomans respectively to reduce soil erosion out-of-field effects. Also high-income، higher education and Marital status desire paying for improvement environment quality، but this is vice versa for old and employed people. According to results، it is very important to perform soil conservation projects for improvement of environmental situation for citizens. Thus it is necessary to extension and culture making for more understanding the soil conservation by farmers and establishes grant-in-aid water and soil quality improvement.

Restoring high value medicinal and industrial plant species requires identifying habitat potentials of the target species. This study aimed to generate Astragalus verus potential distribution map in Fereydunshahr rangeland، Isfahan Province. First، soil maps were obtained from 70 soil profiles and climatic maps were produced from 10 climatic stations data. Geostatistical methods were used to convert the obtained data to digital maps with 90 by 90 meter resolutions. Finally potential distribution map of the species in the study area، was produced using presence-absence data of 100 sites and performing Logistic regression method. According to results، annual mean precipitation، clay، mean temperature of warmest season and slope were the most important environmental factors influencing the distribution of the species. According to model output، 21 and 27 percent of the whole study area had excellent and fair habitat condition for the species، respectively. The produced species distribution model had good accuracy as calculated Kappa coefficient and ROC area under curve plots were 0. 75 and 0. 5، respectively. This modeling approach enables to allocate appropriate areas to protect and restore valuable native plant species such as Astragalus verus.

Mapping Land use from satellite images facilitate to reveal changes over a period. There are different methods to detect the changes. In this study، Landsat satellite images have been used for the 1988-2007 periods، and six techniques were applied to detect changes in desert areas of Mehran in Ilam province with an area of 146،265 hectares. Changes detection techniques used in this study are Including of image differencing، principal components analysis، the normalized difference land cover index، conventional components analysis، difference Tasseled Cap (light) and post-classification method. In this study the threshold in the methods that requier the threshold were determind statistically. On this basis، it is known that the threshold change in the region is ±1 standard deviation from the mean. After detecting the change threshold، areas with decrease and increase in changes and no change were identified. In order to assess the accuracy of the changes detection techniques ground truth map and field data were used and overall accuracy and Kappa coefficient wewre calculated. Based on the results it was found that the difference method of infrared band with overall accuracy and Kappa coefficient of، respectively، 95. 66 and 0. 94 was the most accurate، and difference method of CCA2 with overall accuracy and Kappa coefficient of، respectively، 29 and 0. 16 was the least accurate method in detecting changes in land use in the area under the study.

Zygophyllum atriplicoides is a native species in Iran and grows in the large part of the country. One of the main habitats of this species is semi-arid regions of Isfahan province. In the present study، three Zygophyllum atriplicoides habitats were identified in Isfahan province. Process of collecting vegetative information was accomplished using staratified random sampling. Statistical analysis were done on laboratory data and field such as comparing mean، simple correlation، regression and ordination. Relationship between soil، climate and physiographic factors with vegetative parameters (Canopy cover، plant density and average height)، were studied. Results showed that all three regional climates، were semi-arid based on Demarton classification method and average precipitation in these areas is 140 mm. The most important factors affecting growth of Zygophyllum atriplicoides includ magnesium، calcium and soil saturation. The most adverse parameters are sodium، sodium absorption ratio، exchangeable sodium percentage، lime and gypsum. Altitude shows a direct relation with the average height of Zygophyllum atriplicoides.

Drought is a natural phenomenon which may happen everywhere and cause remarkable damages to human and natural structures. In this study، two types of artificial Neural networks; multilayer perceptron، radial basis function، as well as time series models have been used to predict the standardized pereipitation drought index. To this end، the amount of standard precipitation index was calculated firstly in the selected stations of Khuzestan province in three، six، nine، and twelve months periods. Finally، the amount of standard precipitation index was predicted using the artificial Neural network and time series models. The results showed that the time series models have better performance in predicting the amount of standard precipitation index in all of the mentioned time periods in comparison to the artificial Neural network. In addition، the results indicated that the multilayer perceptron could better predict the amount of standard precipitation index in all periods comparing to the radial basis function.