نشریه خشک بوم
سال هشتم شماره 1 (بهار و تابستان 1397)

Effect of SiO2 nanoparticles on rangeland plant of Bromus kopetdaghensis Drobov organs is accomplished through factorial test in a completely randomized design with four replications at Ferdowsi University of Mashhad, in 2014. Treatments included two levels of application (spray and impregnated with seeds), 5 concentrations level of SiO2 nanoparticles (1, 2, 10, 50, and 80 mg/l), and control (no SiO2 nanoparticles). Results showed that increase in concentration of nanoparticles, the plant organs such as height and weight parameters were decreased. However, SiO2 nanoparticles at low concentrations at the application of SiO2 nanoparticles method impregnated with the seed at a concentration of 10 mg/l and spraying nanoparticles at a concentration of 2 mg/l were increased plant height and weight, compared to treatment the control. Application of SiO2 nanoparticles are coated with seed treatments with a concentration of 10 mg/l was shown 24, 66 and 34 percent incensement, respectively for shoot dry weight, root dry weight and height compared to the control treatment. Application of spraying nanoparticles treated with 2 mg was shown 27, 68 and 35 percent incensement respectively for shoot dry weight, root dry weight and height compared to the control treatment. According to Bromus kopetdaghensis D. yield, it is suggested the method of SiO2 nanoparticles application impregnated with seed at a concentration of 10 mg/l due to lower consumption of nanoparticles, ease of nanoparticles use and being economical at natural lands.

Detection and prediction of changes in landscape, is necessary for the maintenance of an ecosystem, especially in developing countries with rapid changes and without planning. The object of this research, is monitoring landscape changes in past and it’s simulation for future using Markov chain Consolidated and automated cells (CA-Markov) in arid and semi-arid region of Meymeh Dehloran, Ilam. Landsat satellite images of (TM) 1985, Landsat (TM) 2000 and Landsat (ETM) 2016 were used. Change detection maps were prepared in seven classes of agriculture, Forest, fair range, poor range, rocky protrusions, residential land and salt land using supervised classification ARTMAP FUZZY neural network. Accuracy of the classification landscape maps for 1985, 2000 and 2016, are 93, 95 and 93 percent, respectively. Changes in landscape were predicted for 2030, using Markov chain model and automated cells. Predicted matrix results based on 2001 and 2016 maps showed that in span of 2016-2030, it is likely that 13% of agricultural land, 54% of Forest, 48% of the fair range, 82% of poor range, 55% of rocky protrusions, 52% of the residential land, 93% of salt lands and marsh land converted to other land uses. To validating the model, simulated landscape map of 2016, were compared with satellite image classification of the same year. Kappa coefficient was 87%, which shows the high capabilities of CA-Markov model to simulate landscape changes in arid and semi-arid region of Meymeh Dehloran.

This study aimed to investigate effect of saline water stress on growth and physiological characteristics of Calotropis procera seedling in greenhouse conditions. Experiment was performed at six salinity levels (0, 5, 10, 15, 20 and 25 dS/m) in a completely randomized design for 5 months. Survival percentage of milkweed seedlings at salinity levels of 0, 5, 10 and 15 dS/m was 100, 100, 64/6 and 22/6, respectively; however, at 20 and 25 dS/m seedlings did not survive. Maximum rate of root length and volume were observed at control treatment. Maximum rates of photosynthesis, stomatal conductance, transpiration, shoot and root dry weight, seedling height, collar diameter and number of leaves were belonged to control treatment. Maximal level of leaf temperature and root/shoot ratio were observed at salinity 15 and 25 dS/m, respectively. Totally, findings of this study revealed that five month seedlings of milkweed have poor viability at salinity conditions of 15 dS/m, although at salinity of 10 dS/m showed fairly well adaptation from the many growth and physiological characteristics, and also survival point of view.

This research was conducted in Yazd- Ardakan plain to determine biomass of Saxaul shrubs. Twenty shrubs were selected randomly for cutting down. Standing attributes include diameter at root collar (DRC), height, stems number and crown diameters were measured. Stem and leaves were separated and weighted and some samples were taken to determine dry/wet weight ratio. Above-ground biomass of the shrubs was calculated according to dry/wet weight ratio. Linear regression analysis was conducted for predicting biomass of the shrubs. Results indicated that there was strong correlation between above-ground biomass and diameter at root collar. The best models were detected for trunk dry weight- DRC (R2=0.82), Above-ground biomass- DRC (R2=0.84) and branch dry weight-crown area (R2=0.75). Models based on crown diameter and height were significant and could predict 60 to 70 presents of variations in biomass. Finally, it can be concluded that diameter at root collar is the best predictor of biomass in saxaul plantations. Also age-specific equations provide better predictions of biomass with lower error, provided that sample size is sufficient.

Nowadays, the development of green space with ornamental species of cypress is a common in different dry areas of Iran. Regarding the limitation of water resources in dry areas, study on the response of cypresses to drought is essential. This study was carried out to recognize the responses of survival, growth, gas exchange and water relations in seedlings of two cypress species (Cupressus arizonica and C. sempervirens var. fastigiata) under water deficit condition in greenhouse. The experiment was conducted as complete randomized block design with different watering levels (3, 6 and 9 days) in three replicates. Results showed that water deficit had a significant effect on most of the traits measured in seedlings. Survival of C. sempervirens at 9-day irrigation was decreased about 50.2% but in C. arizonica seedling no mortality was detected in each watering level. During drought application, shoot growth and diameter growth in both species prominently decreased, while at 6- and 9-day irrigation, shoot growth in C. arizonica was 43-47% greater than that in C. sempervirens. With increasing drought, photosynthesis activity, stomotal conductance and water potential decreased but intracellular CO2 concentration (Ci) and leaf temperature did not change. Transpiration rate and relative water content (RWC) of leaf were significantly decreased in both species, but in C. arizonica the decrease of transpiration rate at 6- and 9-day irrigation was 12-32/3% less than that in C. sempervirens. Generally, it can be stated that C. arizonica seedling is more tolerant than C. sempervirens seedling under drought stress.

Evaporation is one of the most important sensible losses from water resourcese, especially in desert areas that humans have the lowest level of intervention. Climate is the most important index at the amount of these losses in different areas. Different methods has been presented for reducing of water evaporation rate . In this study, in order to evaporation reduction from tailing dams and open water resources of Sarcheshmeh copper complex investigated performance of three types balls as evaporation reducing coating for the first time. Used balls are different in the mechanism of action, size and material. They are including two types of polyethylene balls, mono-aperture and multi-aperture, with a diameter of 8 cm and a type of small polypropylene white ball with a diameter of 1 cm. For evaluating of performance of these coatings, several small ponds with an area of 1m2 in the vicinity of Sarcheshmeh tailing dam were built and evaporation losses were measured for a month from 03.04.2016 until 03.05.2016 in each covers with two repeats. Based on the Tukey and Duncan multiple comparison tests, there are significant differences between covers, in 5% significant level. Results showed, the mono-aperture balls with performance of 65.1%, had the greatest impact on reducing evaporation, while multi-aperture balls and small balls with 51.7% and 38.8% respectively were in the next priorities. Finally, the mono-aperture balls were identified as the best evaporation reducing coating, because these types of balls had the most roughness on the surface and amount of empty spaces was constant in during time.

More than 75% of Iran is located in arid and semi-arid areas. These areas have intensive and irregular distribution rainfall. Most rainfall exit from these areas as flood waters. Exact estimation of flood-water peak discharge and prioritizing the flooding potential in necessary in every subwatersheds although because of economic restriction, watershed restoring is not practicable in all subwatersheds. This study was done in Sarkhoon watershed of Bandarabbas in south of Iran that located in arid areas in Iran. For flooding prioritizing in subwatersheds we used of Electre III method (that is one of multicriteria method( and flood flow coefficient formula. For enter the information, based the viewpoints of experts and references review, 7 criteria was selected that includes: Basin mean weight slope, gravilus coefficient, permeability, runoff coefficient, shape coefficient, vegetation cover and rainfall intensity. Then the criteria weights was calculated using AHPmethod and for select the best hierarchy and function of electret and flooding coefficient, we used of spearman correlation (r=0.85) so using of ElectreIII method can be a good method for flooding potential in these subwatersheds, finally for final ranking we used of combination method. Results showed that suwatersheds 18-1-1, 14 and 18-1-2 are under severe flooding in comparison with other subwatersheds.

One of the most important international issues is increasing of global warming and global climate change. Global warming and temperature peaks in recent decades, especially in the 1990s, have increased, and recorded the world's warmest year in the last 150 years in 2016. Changes in temperature and precipitation are in line with the changes in the large hydrological cycle and have caused wide variations in climate, such as atmospheric changes, changes in rainfall patterns, and extreme temperatures.
The aim of this study was to investigate temperature and precipitation changes in the Yazd-Ardakan basin and ten stations were used to study temperature and precipitation during the period 1975-2005.
The results indicate a rise in temperature of 0.5 °C in the Yazd-Ardakan plain in the 30 year period of 2016-2045 The result is consistent with the IPCC forecast that global warming is set at 0.2 °C per decade. Also the results of the model output show that the average rainfall variation of stations is 8.8 percent lower than the average observation period. The monthly precipitation of stations indicates a decrease in winter rainfall and an increase in precipitation in the spring, a subject that confirms the rainfall data of the stations in the current situation.
Future climate change in the environmental issues of Yazd province, especially in the field of water, can affect the future and its sustainability.