DESERT ECOSYSTEM ENGINEERING JOURNAL
Year:2017 | Volume:6 | Issue:16 |Papers Count:12

Astragalus podolobus is a native species of Turkmen Sahra and is used in rangelands in arid and semi-arid hilly loess soil located in north of Gonbad-e Qabus. For cultivation and establishment of this species, different propagation methods for the experiments had been used in pastures of Dashli Borun. In this study, 4 treatments for propagation and 6 treatments for establishment of this species were considered. For propagation of this plant, 4 treatments, including NAA and IBA hormones, were applied for cuttings and reproduction of plants by seeds. The experiments were conducted as completely randomized design. SPSS software was used for statistical analysis. The results showed that propagation by seed is the most appropriate method for A. podolobus plant. Thirty percent of seedling survived when seeds were used for propagation in plastic pots. In the cultivation and establishment of seedlings in rangeland in March, 91% survival rate was observed and in December, survival rate was recorded as 65%. Growing plants from seedlings cultivated in December showed more vigorous growth than the winter cultivation.

Plant species distribution, composition and diversity in deserts of arid and semi-arid areas, especially saltland; depend on soil physical and chemical gradients. The aim of this research was to investigate changes in the plant species diversity and richness along a soil salinity gradient in the margin rangelands of Petregan Playa. After vegetation zoning in relation to soil salinity, random-systematic sampling within each zone was taken. Within each zone, three stands were selected, then, within each stand, plant vegetation cover, density and species diversity indices were measured. For ordination vegetation along the soil salinity gradient, Detrended Correspondence Analysis (DCA) method was used. The results showed that there were significant differences in the plant total cover, annuals and perennials plant cover between different soil salinity zones. Also, the soil salinity gradient has a significant effect on the species richness and diversity, as the first zone (high salinity) has the lowest species richness and diversity. It can be concluded that, in general, only high salinity level has a significant effect on the plant species diversity.

Based on the importance of runoff harvesting method in arid lands, effect of these systems on vegetation production and cover and soil moisture was evaluated. Soil and vegetation were sampled in three sampling areas (Control, Curved pits, Catchment ponds) using randomly-systematic method and in each site (50 hectares), 98 plots were sampled with intervals of 70 m within plots of 1*2 m and in total, 294 plots were used. Yearly growth of the vegetation was cut within 25% of the total plots (294) and was dried and its weight was considered as vegetation production. Twenty percent of total plots related to vegetation cover in each site were selected and two soil samples were sampled in each plot to evaluate soil moisture variation in two depths. The results revealed that the cover percentage as well as vegetation production increased at about 2 times in catchment ponds site and 1.5 times in curved pits site in comparison to the control site. According to the results, it seems that catchment pond method has better performance in comparison to the curved pit for increasing soil moisture and vegetation production and therefore priority of these systems can be advised for rangeland improvement and reclamation in arid lands.

Fire can influence the stability of many natural habitats via changes in biological, chemical and physical properties of soil. The aim of the present study was to investigate the effects of fire on some chemical properties and nutrients availability in a rangeland soil. To perform this research, a fired area with a five-month history and a homogenized area close to it without fire were selected. Thirty samples of surface soil were collected by establishment of 15 plots in each area. Soil properties were analyzed using SPSS software via independent t-test. The results revealed that the rate of organic matter (2.15 folds), cation exchange capacity (21.65%) and electrical conductivity (3 folds) of fired soil were increased and the content of calcium carbonate equivalent (27.2%) and pH (4.5%) were decreased significantly. Also, the amount of total nitrogen (2.2 folds), available phosphorous (100%), potassium (66.5%), manganese (17 folds) and zinc (2.92 folds) were significantly increased in fired soil. The magnitude of available copper and iron didn’t change as influenced by fire significantly. In general, the results showed that the fertility of soil was promoted as affected by short-term fire; however, long-term effects of fire must be evaluated and compared.

Due to the drought in recent years and the need to increase the efficient use of water in agriculture, the abiotic windbreak appears to be more suitable than biotic. In order to investigate the effects of lattice brick patterns in protection of the windbreak on the back, an experimental study was carried out in a wind tunnel. For this purpose, five lattice brick patterns with different densities, with density of 100% for the control in a randomized complete block design with four replications were studied. The results revealed that with increasing porosity in the windbreaks, while reducing wind speed and keeping the area protected; flow lines become parallel and vortex currents are not observed. While with reduced porosity, the wind streamlines the flow and becomes turbulent and reduces protection in the desired area. Also, results showed that the construction of windbreaks with a height less than the height of the protection structures (like a greenhouse), especially in high-density windbreaks, not only protect against winds not retained, but also with the formation of more rapid and vortex flows behind the windbreaks, the damage increases. Thus, attention to create optimum density with the use of appropriate lattice patterns is important in establishing abiotic brick windbreaks.

The operation of sand transport by erosive winds and its sedimentation around the obstacles such as plants leads to the appearance of the eco-geomorphologic phenomenon of nebka dunes in dry seasons of Golestan province. This study aims to identify the physicochemical characteristics of nebka sediments and compare its results with adjacent lands. Hence, the grain size distribution and morphometric characteristics of particles were determined for 30 samples in Sufikam plain in the Eastern border of Caspian Sea. Then, the relationships between the physicochemical properties were compared using Wilcoxon and T-test at 95%. Results showed that the prevailing wind direction is west to east which in our case is from sea to land. Analysis of sand rose graph indicates that the winds in spring and summer blowed the sediments from soil surface. Results showed that there were no significant differences between sorting of particles, fraction of very fine sand, silt, clay, EC, pH and organic carbon of nebka's head samples and its adjacent land. However, results of skewness index, mean diameter of fine sand, medium sand, coarse and very coarse sand, SAR and ESP proved to be statistically significant. Therefore, it can be concluded that the source of sediments is local.

Dust emission and sand mobilization are the common natural hazards in desert roads of Iran, which originate from geomorphological facies of road margin. In this study, the geomorphological units of Yazd-Meybod road margin were distinguished, and the samples were taken from these facies as origin area while roads sediment as the transition area of sediments. The samples were analyzed using morphometric indices and microscopic mineralogy; then, its results were compared using cluster analysis method. The results showed that the median and mean of road sediment grain is 208 and 224 μm, respectively which according to the relationship between transportation distance and diameter of grains in deposition area prove that the origin area could be close to sedimentation area. The skewness index of grain size distribution tends to show coarser grains and poor sorting for road sediments which revealed the local transportation area of sediment particles. The results of mineralogy between road sediments and geomorphological facies around the road showed that the aeolian sediments crossing the road were more similar to sand sheets and sand dunes which can be introduced as the source area of aeolian sediments on the Yazd- Meybod road.

Ecosystems are degraded through human activities and a healthy ecosystem sustains the requirements of human and natural environment, as well as the conservation of economic and social values. Various indicators are required to assess the health of ecosystems. This study evaluates the factors affecting the overall ecosystems health including: vigor, structure, and resilience in the Iiril watershed, Ardabil province. The values of vigor (NDVI, erosion and runoff), structure (continuity, degree of division, patch density and edge density) and resilience (landuse classes, the largest patch index and aggregation index) were quantified and then results were compared at sub-watershed scale. According to the results of vigor component, the S8 and S1 sub-watersheds had the highest scores of 0.89 and 0.13, respectively. The S7, S2 and S3 sub-watersheds had favorable structure conditions, having 0.73, 0.63, and 0.63 scores compared with other sub-watersheds. The resilience index values of S1, S3 and S8 sub-watersheds were in a high health level. In summary, the highest variability is related to resilience component over the study area. The average value of the vigor, structure, and resilience components were calculated to be 0.40, 0.55, and 0.55, respectively, and the S1 sub-watershed had the highest average value of calculation indices.

One of the most important issues in watershed management is to determine priority for implementing managerial activities. According to the management and decision-making for selecting appropriate locations to implement watershed management projects and also, due to the cost and duration of watershed operations, using decision making methods are very useful. In this study, by using fuzzy SAW and AHP decision models, Parchin’s sub-basins of Tehran province have been prioritized based on eight criteria including area, average slope, form factor, time of concentration, average CN, drainage density, t average annual precipitation and elevation. The obtained results showed that according to the above-mentioned methods, the highest priority is for basin 7 among all the sub-basins. In Fuzzy SAW method, sub-basin 7 with 1.86 has the highest score while sub-basin 9 with 1.69 was in the second order. Likewise, in AHP method, sub-basin 7 with the score of 0.2102 has the first weighted priority and sub-basin 9 has the second priority. According to comparison of two methods, it can be said that the first and second priorities of both models are similar in the study, but in other sub-basins, priorities are varied.

Climate change and drought have negative consequences, including the spread of deserts. In this research, the impact of climate change on some climatic variables (temperature and precipitation) of Firoozkooh and Garmsar synoptic stations in the period 2030-2011 and 2065-2046 using LARS-WG model under scenario A2, B2 and A1B and finally desertification hazard and risk using ESAs model in Hablehroud basin due to ecological sensitivity of this area were assessed. The results revealed that the precipitation in the near future will increase from 0.23 to 4.80 mm and in the middle future will decrease from 0.80 to 0.15 mm. The minimum and maximum temperatures will increase for both future periods. Most changes in desertification classes in the near future are related to scenario B1 and scenario A1B in the middle future, in which we can consider transition and change of hazard classes (F2, F3 and C1) to the critical classes (C3 and C4). In both future periods, the percentage of the risk classes area of IV and V (critical) will increase. Therefore, this increase for the middle future will be from 15.49% for scenario B1 and class IV up to 77.50% for scenario A2 and class V.

Presently, significant growth of ecotourism is due to its special place in scientific and economic communities as well as the positive impact on environmental attitudes, sustainable development and revenue. The aims of this study are to develop a method based on field studies and questionnaire, to evaluate the ecotourism development potential in Abbas Abad wildlife refuge. According to field surveys and experts’ opinion, ecological value of the biosite was estimated using sum of scientific and supplement criteria. Then, its management value was achieved using sum of protection and efficiency criteria. Results revealed that Abbas Abad biosite with a value of 15.6 has high potential for development of sustainable ecotourism. Mean values of ecological and management criteria are9.05 and 6.01, respectively, and supplement criteria with amount of 93.55% has the highest value. In the scientific criteria, indices of the rare species of animals and plants, and the biological attractions and geotourism phenomena introduced in magazines, respectively, with values of 1 and 0.5 have been allocated the maximum score. Therefore, with the introduction of the ecology and management values of Abbas Abad wildlife refuge and planning according to its capabilities, the biosite can become a top destination for tourists and nature lovers.

Fars province is regarded as one of the important poles of tourism in Iran, because it has enormous potential in terms of natural, historical and cultural attractions. Such cases can be noted in arid areas and deserts and can have very high potential in attracting tourists. In this research, with an emphasis on the desert areas of tourism, the tourism potential in three playas: Shiraz, Neyriz, Meydane Gel were evaluated using both tourists, expert, and data knowledge comparitively. Thus, first, in order to investigate the potential of the three playas, questionnaires from the perspective of tourists and experts were used, and ArcGIS software was used for preparation of layers in data knowledge. Then, TOPSIS model was used to rank the deserts in the form of three scenarios. The results showed that in all three scenarios, Shiraz desert with an average score of 0.95 was ranked first, and then Neyriz deserts and Meydane gel with mean of 0.71 and 0.14 were prioritized in the second and third orders. Therefore, in the development of ecotourism desert in Fars province, Shiraz desert has the highest priority which is prone to develop ecotourism desert.