نشریه مهندسی اکوسیستم بیابان
پیاپی 11 (تابستان 1395)

Syrian bean caper (Zygophyllum fabago L.) grows in dry and uncultivable wastelands. Because of high tolerance to adverse conditions, an experiment was designed and fulfilled to investigate the effect of two environmental factors, light and temperature, on Syrian bean caper seed germination. Experiment was performed in a completely randomized design with two levels of light (light and dark) and two levels of temperature (22 and 28 ᵒC) in three replicates. Sterilized seeds were placed in light or dark under 22 or 28 ᵒC temperatures. At 7th days of germination, root and shoot lengths, fresh and dry weights and seed vigor were measured. Analysis of variance showed that germination percent, root and shoot lengths and seed vigor were, significantly, affected by the main effect and interaction of light and temperature. The highest percentage of germination was scored at 28 ᵒC and dark. The light at 22 ᵒC had a positive effect on germination of seeds. The results suggest that light at low temperature and dark in high temperature increased, considerably, syrian bean caper seed germination. The results can be used for culture and make up the vegetation cover by Zygophyllum in aired and desert regions.

Grazing of Livestock is one of the factors having influence on the structure and dynamics of the range land vegetation. Grazing management is a vital factor to control the intensity of the rangeland ecosystems degradation. In this study, plant functional traits and diversity and richness properties were used to assess the vegetation response to different grazing intensities. This was done in Nodushan Rangelands in Yazd province. Vegetation cover was recorded under three grazing intensities (heavy, moderate and light rates grazing). Results showed that the cover percentage of Compositeae and Papilionaceae, significantly showed a negative response to grazing intensity while Gramineae was not significantly affected by different grazing pressure. Some functional groups such as annuals, Geophytes, Chamaephytes, Shrubs and Forbs significantly reduced from light to heavy rates. On the other hands, Therophyts and hemicryptophytes were increased. The other findings of this study showed that decreaser plants significantly had less cover under heavy grazing whereas increaser plants had greater cover under heavy grazing. Also diversity and richness had no significant response to grazing intensity. The results of this research showed that plant traits may change under grazing intensity. In conclusion, we recommend using these traits that show the highest response along the grazing as intensity gradient in the arid rangelands.

Arid ecosystems and deserts cover much of the Iran’s land. These areas are exploited by local communities. Considering the importance of the conservation and development of natural ecosystems in the arid regions, a study was done to assess factors influencing usage of rangeland conservation practices by exploiters through combination of survey methods and case study in arid rangeland of Bardaskan County. Data were collected using existing documents, focus groups, semi-structured and structured interviews by questionnaires filled by 222 rural exploiters chosen through a randomized multi stage sampling technique. Finally, data were analyzed using SPSS software for Windows. Findings shows that exploiters have a vast knowledge regarding the role, importance and affecting factors on rangeland degradation but their actions about mechanical operations are in a low level. The results also showed that exploiters action in the field of biological and grazing management operations have significant positive relationship with the implementation of rangeland management plans, interaction with external organizations, participating in the extension courses, increasing education and increasing levels of farm and garden area. Based on path analysis, 37% changes of farmers actions regarding the rangeland conservation explained by variables of restoration actions, the knowledge regarding the conservation operations, interaction with external institutions, education, number of taken courses. It can be concluded that educational activities and interaction with external institutions can be effective in increasing exploiters’ knowledge, their actions and sustainable exploitation of rangelands.

The aim of this study is evaluation the effect of soil, sludge and wastewater on growth characteristics (height, number of leaves and fresh weight) of and plant. For this purpose, 3 sludge treatment, 2 type of soil and 4 levels of irrigation and SPSS 18 were used. The results showed that in all three characteristics of plant growth, increasing height in crop soil is more than the Sejzy soil. In the Haloxylon pp plant, with increasing levels of waste water and sludge, reduced height. And in plant varies according to soil type. Some of branches in the Haloxylon pp plant by increasing sewage sludge levels is decreasing and it shows different effect in different wastewater levels. But in the Nitraria schoberi plant different wastewater levels in both of soil type hadnt significant impact. Increase sludge levels in crop soil; increase the number of branches and Sjzy soil showed an insignificant effect. Effect of different sludge on fresh weight in Haloxylon pp plant is decreasing and different effect in different wastewater levels. But in the Nitraria schoberi plant, effluent impact is not significant. In the Sejzy soil, increasing of sludge levels due to decreasing of fresh water and in crop soil is opposite

In order to evaluate the intensity and stage of drought stress on agronomic characteristics and drought tolerance of common bean (Phaseolus vulgaris L.), a split plot factorial experiment was conducted in a randomized complete block design with three replications at Shahrekord University in 2013 and 2014. Drought stress treatments and levels of irrigation regimes were considered at vegetative growth (V4), flowering (R5) and pod filling (R7) stages and 60, 80 and 100 percent of full irrigation. The results showed that the maximum number of seeds per pod in Talash cultivar was related to 80 percent water deficit conditions. The maximum 100-seed weight for Talash and Daneshkadeh cultivars was belonging to 80 percent of irrigation. The maximum 100-seed weight was obtained from pod filling drought stress stage. The maximum number of pods per plant was belonging to Talash cultivar with 100 percent of irrigation at vegetative stage while the minimum number was obtained from Daneshkadeh cultivar with 60 percent of irrigation at flowering stage. The maximum grain yield was belonging to Talash cultivar with 80 percent of irrigation at pod filling stage. Also, in case of drought resistance in two bean cultivars, the tolerance and stress susceptibility indices (TOL and SSI) showed significant differences.

One of the important factors affecting on the erosion is lithological characteristics in the watershed. Due to the characteristics of the watershed can be considered reaction of rock to the process of weathering and erosion in the study. In the research of erosion and soil conservation investigate the lithological characteristics of the study area is very important. According to the study area (north of the Darab city) is located in arid and semi-arid and it is able to water erosion, the aim of the study area is investigation the characteristics geological formations, determination of sensitive the area to water erosion in the northern of Darab city. Also in the research, relationship between lithological characteristics and Normalized Difference Vegetation Index (NDVI) was determined. After preparing the geology map and determining the type of formations in the region, based on resource was obtained sensitivity of formations in the study area. Finally, relationship between NDVI and sensitivity of geological formations to water erosion using Landsat 8 images in 2015 was determined. Also for preparing the landform map used topography position index (TPI) in the study area. The inputs data for preparing the TPI was slope, min curvature, max curvature, plan and profile. The results showed that there were 4 classes of sensitivity that consist of low sensitivity, medium sensitivity, high sensitivity and very high sensitivity in the study area. So that 40.22, 26.81, 20.11 and 13.41 km2 were in classes of low sensitivity, medium sensitivity, high sensitivity and very high sensitivity to water erosion respectively in the study area. Also the results showed that EMas-ja with low sensitivity had the highest NDVI (0.457). So the EMas-ja was suitable for growing of vegetation and had low erosion in the study area. The results showed that the study area was classified ten classes that consist of canyons, deeply incised streams, midslope drainages, shallow valleys, upland drainages, headwaters, u-shaped valleys, plains small, open slopes, upper slopes, mesas, local ridges/hills in valleys, midslope ridges, small hills in plains, mountain tops, high ridges. The highest area of landform was canyons, deeply incised streams (44.36%) and mountain tops, high ridges (33.38%). While the lowest area of landform was plain small (0.12%)

Nowadays, desertification is one of the ecological crises of the world. To control Desertification, having a clear understanding of its factors and processes is necessary. KALMAND Protected Area region of Yazd with area of 71269.37 Hectares’ was considered to evaluate current Condition of desertification using ICD. Iranian Classification of Desertification (ICD) was presented by M. Ekhtesasi and S. Mohajeri in 1995. First of all, available data were collected and basic studies were done. The data were entered in GIS and basic maps were produced through interpretation of aerial photos and satellite images using Arc view software. Ten desert homogenous units were separated according to the studies and by overlaying Geomorphology, land use and vegetation cover maps. In next stage, effective factors in Desertification including three environmental factors, three anthropogenic factors, soil erosion Index, resilience potential and reconstruction of ecosystem were scored in a range of 0-10. Afterward, according to the sum of scores and comparing with table of desertification severity Index, final desertification map was produced. The result showed that based on ICD models, the areas is classified into low and moderated desertification. The environmental factors were determined as the main factor in desertification. Most main criterion in desertification of this region was Soil Degradation

Widespread and long-term effects of droughts has caused it to be known as the worst natural disaster that causes water and food deficiency in affected areas. One of the popular indexes in recognizing and monitoring of drought is Standardized Precipitation Index (SPI) that its efficiency has been approved in the world. Trend detection is very important to manage water resources. The Mann-Kendall estimator non-parametric tests are used in climatological factors trend. The SPI has been extensively applied for spatial drought analysis in various regions. Central Iran has been located among the Alborz Mountains in the north, the Zagros Mountains in the south and west, and the scattered mountains of Khorasan in the east. Because of special conditions the average annual rainfall within this area is less than 300 mm. In this study, the monthly precipitation data were obtained from Iran Meteorological Organization and after calculating SPIs in different time series (1, 3, 6, 9, 12, 24 and 48 monthly) precipitation and drought trends were investigated in all station. An investigation of precipitation and SPI drought trend was done in central Iran using Man-Kendal. The results show a significant negative trend in all station except in two stations, so it can be said that aridity in Central Iran has been increased during past five decades. Also based on achieve result in this study, long term time series can show more significant trend rather than short ones.

Drought and overexploitation of groundwater should control the aquifer properties (e.g. storage coefficient and transmisivity). The role of stress factors is identified when the performance of aquifer hydrodynamic coefficients be studied. Since in the most aquifers, allocation and utilization management is based on the pumping test in the past, it would not be expected the optimal management. In order, in this study, the condition of occurrence of groundwater drought periods was investigated using SGI Index. Afterward, two periods of drought in late 1990s and late 2000s which had the severe and very severe drought status was selected as entered stresses to aquifer system. In these periods, the results of pumping tests in exploitation wells (that had the conditions of complete wells) were used to determine the hydrodynamic coefficients of the aquifer. Estimating of hydrodynamic coefficients in the exploitation wells was done using Moench Model. This model is considered the errors caused by instantaneous drainage, wellbore storage and the lack of compressibility unconfined aquifer. Coefficients obtained were compared with the pumping tests and Geoelectric studies (at the beginning of the study period (in early 2000s)). The Results showed that in both drought periods, the aquifer hydrodynamic coefficients had a reduction in comparison with baseline period. In case of transmisivity of aquifer, most its value has been occurred about 100 to 320 m2/day in late of 2000s in different places of plain. This is indicative the reduction of permeability and decrease of saturated zone thickness of aquifer due to drought and overexploitation. In this period, the results also showed that storage coefficient have been reduced from 3 to 10 percent to initial period. For both parameters investigated (storage coefficient and transmisivity), the results of compare means using t test in confidence level 95% showed that there is a significant discrepancy between values of each parameter during stress period to primarily years. In general, with increasing of drought severity and overexploitation of groundwater, different sections of the Aleshtar plain have been experienced lower hydrodynamic coefficients in wider areas.

Drought is one of the most important natural hazards that should affect Agriculture and water resources. The frequency of its occurrence, especially in arid and semi-arid areas of Iran is very high. Therefore simulation and drought forecasting is necessary more than ever. This factor is importance in the planning and management of natural resources and water resources. In this study seasonal drought over the 5 next years (from winter of 2015 to autumn of 2019) in Tehran station was evaluated using RDI drought index, time series models and ITSM software. In this research climate data of Tehran station from 1967 to 2014 was analyzed (with average precipitation of 239.67 mm/year). Based on Hannan-Rissanen MA (5) model method was the best model fitted to the data. According to results coefficients of model (Z(t-1)) at 3 and 4 lags are insignificant (at the 95% level), therefore this coefficients set zero. According to p-value of Ljung - Box test (0.894) in different lags that is significant in 95% level can be said that the prediction is Reliable. Based on results seasonal drought condition in 50% of predicted seasons will be normal, in 45% of predicted seasons will be near normal and in 5% of predicted seasons will be moderately drought.

In arid and semiarid regions, water demands of different sectors are related to groundwater resources. Therefore, the assessment of its changes is very important to achieve sustainable development and optimal management of aquifers in the future periods. The aim of this study was to evaluate the effects of climate change on Islamabad aquifer. For this purpose, the output of general circulation climate models was used. For the generation of future weather data in the region, LARS-WG model was calibrated using meteorological data and then, HADCM3 model was applied and its results was downscaled using LARS-WG model in Islam Abad synoptic station for period of 2011 to 2030. The impacts of climate change on groundwater resources were analyzed based on A2 scenario in the period of 2011 to 2030. Then, optimization of these resources was done using LINGO software. Results of LARS-WG model indicated that the monthly rainfall, minimum and maximum temperatures and radiation will change to 2.04, 2.31, 13.66 and 0.4 %, respectively, compared to the baseline period. These conditions affect water demand and available water volume. Moreover, the benefits of optimizing agricultural production in terms of climate change to the current situation dropped to 3.9%.