نشریه مهندسی اکوسیستم بیابان
پیاپی 3 (زمستان 1392)

Climate change and increase of global warming is one of the most important challenges in sustainable development, which is due to increase of concentration of greenhouse gasses and CO2 in atmosphere. Rangelands have approximately half of the worlds land area and store over third of terrestrial biosphere carbon. Therefore they have a large potential to sequester carbon. In this order, considered the percent of carbon accumulation in two vegetation types (Stipa barbata and Salsola rigida) in Akhtar Abad of Shahre yar in Tehran province. Content and distribution of aboveground, underground biomass, litter and soil carbon was determined. Sampling of plant and soil performed using Random-systematic method and samples transported to laboratory. Soil samples were taken from depth of 0-30 in 15 profiles. Results showed that all of soil properties except to lime and P were significantly different in Stipa barbata and Salsola rigida types. Organic carbon amount in S.rigida soil (33.25 t/ha) was more than organic carbon in S. barbata soil (30.48 t/ha). Control soil organic carbon was smaller than both types (25.52 t/ha). Despite the mentioned amounts of soil carbon, there was no significant difference between S.barbata and S. rigida soils carbon storage. Also no significant difference was observed between control area soil and S. barbata soil carbon accumulation while carbon storage of control and S. salsola soils was significantly different.

Biomass is a key factor in dynamics evaluation of ecosystems, biodiversity level and their stability. Biomass measurement is performed every year to evaluate range ecosystems (investigating the trend of changes), range management (suitable browsing systems) and cover assessment in rangelands. As direct biomass measurement is time-consuming, has costs and destroy rangelands non-destructive methods by modeling can be taken into consideration. On the other hand, introduction of a suitable non-destructive method for biomass estimation that has high speed and precision and low sampling costs has been of importance according to wide areas of range ecosystems in dry parts of Iran, low vegetation cover and sensitivity to destruction. This study was aimed to estimate the biomass of three range species of Polygonum salicornioides, Astragalus ebenoides Boiss, and Astragalus coluteopsis Parsa by an ecological model using a non-destructive method in Sepidan, Iran. The studied species were perennial. Parameters of mean diameter of canopy cover, perimeter and height were used to determine the ecological equations to estimate biomass. About 30 samples of each species were selected for this purpose and measurements were performed in their blooming season. After the measurement of these parameters for each species in the range, their biomass was determined by cut-and-weight method and the ecological equations were constructed. The results showed that the obtained equations were precise enough to estimate biomass due to their correlation coefficient. Between the parameters of mean diameter of canopy cover, perimeter and height mean diameter of canopy cover had the highest correlation with biomass. In all three species, perimeter had the highest correlation after diameter. In general, the results showed that biomass of each species can be estimated by measuring its mean diameter of canopy cover and using the obtained equations for the studied species.

Selecting an optimal interpolation method to estimate characteristics of an area of sampling points is not an important role in data management. One of the important indicators of quality of underground water is the electrical conductivity. Purpose of this study to select a suitability interpolation method from to evaluate and analyze the groundwater salinity SARKHON plain. To this appreciate with use ARC GIS software result of interpolation deferent such as conventional (OK), simple Kriging (SK), and certain procedures such as inverse distance weighted (IDW), radial basis function (RBF), estimated (LPI) and (GPI) was used. The results showed that the specific methods for mapping changes in the EC, (RBF) due to higher R and lower RMSE and MBE are more suitable than other methods determined by the method of by Kriging, ordinary Kriging (OK), the RMSE and MBE having higher and lower R is better than other methods. Conclusion Comparing RBF and is OK with the OK method due to the higher and lower RMSE and MBE ratio RBF method was therefore preferred as a method for mapping changes in salinity, SARKHON plain selection is final. The results show that the quality of drinking water, groundwater SARKHON plain on the diagram in its class (41/5 percent), poor (25/31), Bad (22/5%) and temporary potable (10/89 percent) is located. Plain dark gray and quality of groundwater for agricultural use in two class, the problem of low to moderate (64/8%) and (35/2%) severe problem.

Differences between plant biodiversity and grazing pastures grazed under improved management of rangeland habitat is of particular importance. The purpose of this study was to compare semi-steppe rangeland vegetation of Prdanan in the city of Piranshahr in the field under grazed and enclosed sites were considered. Sampled in both grazed and systematic random pastured five 40 meters transects were done in each study and a total of 40 plots per square were harvested. The results obtained indicate that in enclosed area, 44 species belonging to 35 genera and 14 families and in the grazed area 26 plant species belonging to 24 genera of 11 families were seen, and the greatest cover of the species in the enclosed area is related to the family of Poaceae and Asteraceae respectively with 11/34 and 64/13 percent and in the grazed area is related to the family of Asteraceae and Apiaceae with 74/30 and 08/23 percent. Uniformity and diversity of species richness and index of diversity using Shannon - Wiener, Simpson, alpha Fisher, McIntosh, and Margalef Mnhynyg was calculated by applying EstimateSWin 752, PAST AND BIO-DAP software. The results of the analysis of species richness in both areas claimed that the numerical richness, evenness and diversity of the enclosed area was greater than the under grazed area. The test results showed statistically significant differences between the two arenas by the Shannon index, and Margalef alpha Fisher.

In this survey, the performance of aerial photographs and satellite imagery in determining sand dunes morphology was studied in the Erg of Gavkhouni international wetland located in the southeast part of Isfahan province. Aerial photographs (scale:1:20000) and the panchromatic bands of ETM+ and IRS-P6 sensor were acquired and geometrically corrected using topographic map of the region (scale:1:25000) with RMS error less than one pixel. After this stage, the morphology of sand dunes was extracted from the mosaic of aerial photographs and also panchromatic bands using vector tools in ArcGIS environment. According to the results, five sand dune morphology were determined including transverse dunes, star dunes, silk, seif and reversing dunes. Comparison the morphology and area of dunes extracted from the aerial photographs and IRS_P6 panchromatic band showed that they were mostly similar and this means that satellite panchromatic bands due to their repeatability, cost effectiveness, broad coverage and high spatial resolution can be used as an alternative or complement to aerial photographs for studying sand dune morphology.

In this study, the amount of carbon storage in a Haloxylon aphyllum stands in road edge were measured Garmsar - Eyvanakey highway is a one of the most important and high traffic roads in Iran that adjacent to the Capital, and it's caused air pollutions. We collected 11 plots 500 m2 from the road edges (60 meters on each side from axe) for measurements of vegetation and soil parameters. The results showed that the cumulative carbon sequestration in forest soil profiles in H.aphyllum afforested is equal to 47.72 tons per hectare. The Duncan test results showed no significant difference between the mean layer of 10 to 30 and 30 to 90 cm However, between the two mentioned layers with surface soil (0 -10 cm) have a significant differences (p<0.05). The carbon percentage in the aerial organs included leaves, and steam in compare with below ground biomass have been significant differences. The total amounts of carbon storage in the both of aerial and below ground organs are equal 582.2 Kg per hectare, and also the cumulative carbon sequestrations in soil and plant parts of this afforestations are equals 53.54 tons per hectare. We should consider the potentials of the width of highways, and network roads for carbon sequestrations. The advantages of the establishments of vegetation cover are: decrease and controlled the erosion, make up the ecologically corridors, general landscape, decrease of noise pollution, as well as make up the new microclimate.

Today, the role of soil and water conservation in increase the vegetation and decrease the soil degradation due to its effect in stabilizing soil has a special place. Vegetation can act as a buffer between the land surface and raindrops or prevent the direct impact of raindrops on the soil surface to prevent the phenomenon of disintegration of soil particles and eroding disperses. The purpose of this study was the effect of Biomechanical modifying practice on the soil properties in the dasht kalpush of North Khorasan Province. Sampling In practice area and control area were done by systematic and random method in five slope position. In each slope position, soil sample were taken in practice area from between atriplex and under atriplex that are in contour farrow and in control area in every five slope position soil samples were taken in five repeat and in 0-15 depth. Soil characteristics like bulky density, organic carbon, nitrogen, porosity, carbon sequestration, Na, Ca, Mg, K, and CEC were measure. For analysis of data was used ANOVA and LSD test. Result showed, nitrogen, organic carbon and carbon sequestration in control area were more than two other treatments. Cations in under atriplex are more than two other treatments. Na has increase in under atriplex because of the atriplex effect in absorb sodium from soil.

The optimal management of water resources needs to learn exact and up to date, of how the conditions governing the resources and the status of their future forecasts. one of the methods of management of water resources use methods of the multi criteria decision making. The purpose of this research to choose the best place for the purpose of the earth-fill dam found to develop sustainable water resources. findings and the results of the research indicates that in the above seven large ELECTRE zekr, large (3, 4, 5) with 4 times the domination and 2 times the defeated with (2) points in the first rank, and have been the most appropriate levels for the earth-fill dam, in front of a large (1) with 6 times recessive and without fluency with (6) points in the final ranking and the direction of the earth-fill dam is not appropriate and a large (2, 6, 7) respectively with (2, 2, 1) time mastery and (4, 4, 5) was defeated with rates (1-, 2-, 4-) in the next category. levels of (1, 2, 6, 7) due to the fact that the number of times the one in which the number of non-dominant one in which more and negative points are earned should be deleted.