Journal of Environmental Resources Research
Volume:9 Issue: 1, Winter-Spring 2021

In the present study, the feasibility of planting ash (Fraxinus excelsior L.) and spruce (Picea abies L.) tree species was investigated for rehabilitation of the Toroq Watershed in the northeast of Iran. The estimated land suitability indices ranged from 23.95 to 71.05, and 22.47 to 69.38 for ash and spruce plantations by parametric approach, categorized into moderately suitable (S2) in the east to not suitable (N) in the middle and western parts of the study area. The values of land indices by the AHP approach varied between 35.45 to 94.09 and 34.67 to 83.98 for ash and spruce plantations ranging from highly suitable (S1) in the east to moderately suitable (S2) in the middle and scattered parts in the east and not suitable (N) in the north and southwest of the basin. The results showed that the most important limitations were climate, elevation, soil depth, and soil texture. The regression coefficient (R2) of land suitability indices between parametric and AHP approaches for the two spices was 0.894 and 0.866 respectively. The results of the two models revealed that the moderately suitable class S2 is dominant for ash and spruce plantations in the eastern parts of the basin, while the middle and western parts of the basin were not suitable for plantation of the trees. The findings of this study may help land-use planners to rehabilitate the watershed by expanding forest plantation which ecologically tolerates extreme conditions of the region.

This study was conducted in Jiroft rangeland, Kerman, Iran to assess the effects of different livestock grazing intensities (low, moderate, heavy) on ecological factors, soil properties, and root and shoot carbon and nitrogen pools. In each plant sampling site, five points were selected and five quadrates (a total of 75 quadrats) were investigated. Soil surface samples were taken in quadrats (75 samples). Data analysis was carried out by analysis of variance (SPSS18.0). Findings indicated that canopy cover (46.23%) had the maximum level in the low grazing site. The diversity index was maximum in the overgrazed site (1.63), while the low grazing site had the minimum species diversity (1.27). In the three sites, the nitrogen and carbon pools were higher in the roots compared to the shoots. In the low grazing site, the plants' nitrogen and carbon pools were notably more than the heavy and moderate grazing sites. Potassium (612.87 mg kg-1), nitrogen (3.30 g kg-1), and organic carbon (39.20 mg kg-1) were considerably higher under heavy grazing conditions. However, the low grazing condition resulted in notable enrichment of phosphorus (11.44 mg kg-1). The soil nitrogen and carbon pool in the overgrazed site were higher. In spite of the fact that the soil nutrients in the heavy grazed site were higher because of livestock manure; we could not interpret it as greater soil fertility. Our results suggest that low grazing can be effective for managing plant community and soil quality in arid ecosystems.

Forest ecosystems are complex dynamical systems described by attributes of composition, structure, and function. To understand and manage forest ecosystems, we are required to explain and classify their dynamic structure and spatial patterns. We investigated the spatial patterns of trees and their regenerations in a preserved area in Zagros forests of western Iran. We applied geostatistical methods to examine the spatial pattern in distribution of tree and regeneration density and diversity. Fractal analysis was also used to characterize the complexity of the spatial patterns. The results showed that the mean of tree density per plot was 10.56 (S.E. ± 0.29) individual with canopy cover being 18.1 (S.E. ± 0.96) percent per plot. The mean of regeneration density was 3.06 (S.E. ± 0.23) individual in plot.  We revealed spatially structured characteristics for tree density and diversity indices through the variograms that showed the presence of spatial autocorrelation. We also found that preservation favored density and diversity of tree regeneration in this area compared to unpreserved area. We also found that fractal dimension representing the unpredictability of spatial patterns, is high for trees and regeneration. This implies that although spatial dependence in semivariograms exists, it is generally fairly weak. These results revealed the scattered and homogeneous spatial distribution of trees and their regeneration in Zagros forests. It seems that the preservation action is not yet sufficient to effect on the spatial pattern of regeneration in this area. Therefore, conservation efforts must continue to complete the recovery of regenerated forest and flourishing of their spatial structure

Evapotranspiration after rainfall is the main component of the hydrological cycle that quantifies the amount of water lost. Since climate change directly affects the temperature and rainfall parameters, and the evapotranspiration rate is directly related to the air temperature, it is expected to have significant changes in the future. Therefore, in this research, the possible impacts of climate change on evapotranspiration changes under two RCP2.6 and RCP8.5 climate scenarios are investigated using statistical downscaling model (SDSM) and CanESM2 atmospheric general circulation model output for the future period 2030-2059. Reference evapotranspiration rate was compared with Hargreaves-Samani and Thornthwaite methods in monthly and annual periods for the base and future periods. The results showed a mean increase of annual maximum and minimum temperatures in both scenarios from 0.06 to 0.26 °C compared to the base period. The highest increase was in May by 2.61 °C under the RCP8.5 emission scenario. Overall, the trend of evapotranspiration has been increasing throughout the years. The evapotranspiration in the Hargreaves-Samani method in the RCP8.5 scenario had the highest mean change of 0.08 mm or 2.79%. Although annual changes were not perceptible, as evapotranspiration in the basin reaches its maximum in July, the changes increased by 0.45 mm/day in RCP8.5 scenario. The results of monthly survey can be used in surface and underground water resources management and watershed projects estimating the water needs of plants plus appropriate timing of useful irrigation.

Water as a major necessity of sustainable development is essential for agricultural production and food security. Increasing water productivity, especially in agriculture, is one of the key issues for optimum water resource management. The present study applied a Stochastic Metafrontier Model to estimate Technical Efficiency (TE) and Technology Gap Ratio (TGR) of agricultural production from selected countries. The frontier and metafrontier production functions of 27 countries from 2011 to 2016 were used for estimation of the TE. The results showed that the mean of group efficiency ranged from 0.32 to 0.83 and the mean of technology gap ratio based on water crisis indicator in three groups were 0.37, 0.39 and 0.44, respectively. Considering the global water scarcity mainly in arid and semi-arid environments, it is vital to seek appropriate policies directed towards the provision of technology for irrigation infrastructures that would enhance resource use efficiency

The purpose of the present research was Cadmium (Cd) and Lead (Pb) pollution assessment and monitoring the spatial distribution of soil ‎contamination around the municipal landfill site in southwest of Gorgan, Iran. Thus, in a systematic network with a distance of 250m, from 32 stations three samples of surface soil (0 to ‎‎20cm) were obtained and mixed together. In addition, three samples away from the landfill with similar ‎characteristics and geology were used as control. The concentration of heavy metals for the samples was determined using nitric acid and hydrochloric acid and atomic absorption spectrometry. Mean concentrations of Cd and Pb in the soil around the ‎landfill site were 0.37 and 17.31 mg/kg respectively. The total concentration of Cd and Pb was higher than the control areas. There was a positive correlation between Cd and Pb showing these elements in the soil are from the same origin. Based on our research, soil in the landfill area has a moderate ‎ecological risk index, which is about 120. The central parts of the study area have higher concentrations of Cd and Pb than southern parts due to the slope and runoff of the waste leachate. In general, there was an increase in the concentration of Cd and Pb in the sampling sites ‎compared to the control site.

In a majority of agricultural economics analyses, farmers’ economic welfare is highlighted while the environmental issues are largely ignored. Therefore, the purpose of the present study was to determine the optimal cropping pattern through an environmental approach in a case study in Kazeroun County, Fars, Iran. Data was collected from production costs statistics provided by the Statistics and Information Technology Bureau of Agriculture-Jahad Organization. The optimal cropping pattern was determined through the goal programming model with four goals of maximizing farmers’ net return, minimizing the amount of used water, chemical fertilizers, and pesticides under three scenarios. The results indicated that the third scenario which involved the environmental goals specified by the Islamic Republic of Iran’s 5th Development Plan, was the optimal one. In this scenario, the use of water, chemical fertilizers and pesticides decreased by 4.4%, 4.72%, and 8.33% respectively while the net return increased by 10%. According to the results of the study, it is possible to increase the profit and productivity of resources with regard to environmental issues.

Mining activity is one of the major sources of heavy metal pollution of soil. Most mines are abandoned without any remediation and cause contamination of soil and water. Phytoremediation is an environment-friendly technology for the remediation of contaminated sites. In this work, native plant species were identified that can tolerate high concentrations of heavy metals and are useful for phytoremediation in an abandoned Pb-Zn mine in the north of Iran. Twelve plant species and the corresponding soils were collected and analyzed for As, Cd, Co, Cr, Cu, Mo, Pb, Sb, Ni and Zn contents using inductively coupled plasma mass spectroscopy (ICP-MS). In order to measure the bioavailability of heavy metals for plants uptake, DTPA extraction of heavy metals were determined. Then, the physiochemical characteristics of the soil samples were measured and the translocation factors (TFs) and bio-concentration factors (BFs) were determined. The soil samples were alkaline, and exhibited low electrical conductivity, high cation-exchange capacity, moderate organic carbon content, and clay loam texture. All samples exceeded the soil toxicity thresholds for AS, Cd, Pb, Sb, and Zn. The results indicate that Stachys byzantina has the ability to accumulate significant amounts of Pb in its shoot. The average concentrations of Pb in the soil, shoot, and root were 15472mg kg-1, 1797 mg kg-1, and 371 mg kg-1,respectively, with TF value of 4.8 and BF value of 0.1. Therefore, S. byzantina may have the potential to function as a Pb hyper-accumulator and merits further investigation.

In order to evaluate soil water content and water uptake by corn plant roots (Single cross 260) under different soil moisture and water salinity stresses using the agro-hydrological Soil–Water–Atmosphere–Plant (SWAP) model, an experiment was conducted in 2015 at the green house of the Agriculture Research Center of Shahrood, Iran. The statistical model employed was a split plot based on a randomized complete block design with three replications. The main plots consisted of three levels of irrigation; 50 (I1) (full irrigation as the control), 75 (I2) and 100% (I3) of Total Available Water (TAW) depletion while the sub-plots consisted of three levels of salinity of irrigation water; 2 (S1), 4 (S2) and 6 (S3) ds.m-1. The results showed a good correspondence between the simulated soil moisture, water uptake and measured values. The normalized root mean square error (nRMSE) and the root mean square error (RMSE) values of the predicted soil moisture were 4.58 and 24.96 and for the water uptake by the roots were 23.37 and 35.48, respectively. The R2 of coefficient of simulation for water uptake by roots in different treatments were 0.38 to 0.8. The dataset of the predicted and measured values were close to the 1:1 scale line for both soil moisture and water uptake. This study indicated that the SWAP model can be used as a powerful tool to simulate field water cycle and evaluate irrigation practices. Accordingly, taking into account the existing conditions of the region such as weather and soil type and preparing scenarios based on possible management options, management strategies can be optimized according to the results achieved for the SWAP model simulation.

Land subsidence including downward subsidence with a horizontal displacement vector normally occurs in small amounts. In the present study, two pairs of Sentinel-1A descending and ascending images of 2014 and 2015 were used to survey the subsidence rate in Garmsar Plain. After ensuring the high correlation of the images, their interferogram was prepared and following removal of unnecessary phases, the displacement phase was calculated and converted to the vertical component. The InSAR analysis revealed that the Garmsar Plain witnesses an annual subsidence of 36 cm, which is very close to that of Tehran and Varamin plains. High-subsidence areas are generally located in the northern part of Garmsar, decreasing towards the southeast. The temporal and regional relationships of groundwater data and subsidence suggest that the general pattern of the subsidence in the Garmsar Plain is caused by overexploitation of groundwater that has led to widespread surface deformation. Since Garmsar is close to Tehran metropolis and the industrial boom in this city puts enormous pressure on water resources, there is an urgent need to curb extra groundwater extraction and manage water resources more wisely to decrease the speed of this unrepairable phenomenon in the area.