نشریه مهندسی اکوسیستم بیابان
پیاپی 29 (زمستان 1399)

Wind erosion is a phenomenon that causes severe environmental changes in arid and semi-arid climates. As surface soil texture is very effective in soil erodibility, identifying soil erodibility index is important and efficient. Mismanagement greatly contributes to the development of wind erosion. The velocity that makes the first particles of soil move from the surface is called the erosion threshold speed. Measuring the factors involved in wind erosion has always been difficult and costly. Therefore, using wind tunnels is suggested as an alternative method. This study investigated the physical and chemical properties of soil and their effects on wind erosion.

The Meybod wind canal is located at 32° 07ʹ 00"- 32° 11ʹ 00" and 35° 56ʹ 00"-54° 06ʹ 00". Using satellite images derived from Google Earth and the GIS software and the data gathered via field visits, a study border was designated for the region. Based on the area’s characteristics and the existing facies, a forty-points sampling network was randomly applied to the study area. As for the threshold speed test, first the wind erosion measuring device was placed on the desired point, and the wind speed was increased slowly to reach the erosion threshold speed; then the intended samples were collected from the surface soil (0-5 cm of soil surface). The soil’s physical and chemical properties including sodium, calcium, magnesium, organic carbon, organic matter, salinity, sodium absorption ratio, sand, clay and silt, gravel percentage, as well as soil moisture and texture were measured in the laboratory. In the next step, the Weka 3.8 software was used to determine the role of each physical and chemical parameter on the erosion threshold speed.

 Land use Using the decision tree algorithm, the relationship between land use characteristics of all points with threshold speed was investigated and the results were extracted. The effect of each parameter on the velocity of the erosion threshold was also obtained. Data mining results showed a high correlation between land use parameters and the erosion threshold speed. It was also found that the land use characteristics had a greater impact on the secondary threshold speed.  Physical parameters The results of data mining indicated a significant correlation between physical parameters and the threshold speed. According to the obtained statistical results, it was found that physical properties had the greatest effect on the secondary threshold speed. Therefore, the secondary threshold velocity had been used to examine the correlation and trend.  Chemical properties: The results of data mining suggested a high correlation between chemical parameters and the threshold speed. According to the obtained statistical results, it could be found that chemical properties had a greater effect on the secondary threshold speed; Therefore, to investigate the correlation and the effect of each parameter on the threshold speed, the secondary threshold speed was used. Based on the significant correlation between threshold velocity and erodibility index, it was found that the erodibility index had an effect on the erosion threshold speed. It was also found that the threshold speed decreased with an increase in erodibility index.

This study investigated the effect of physical and chemical properties, and land use on erosion threshold speed using data mining with decision tree algorithm. Moreover, the SPSS software was used for discovering the correlation between those factors and erosion threshold. The results of land use data mining showed that land use characteristics, including surface pavement, cultivation status, and canopy status affected the threshold speed. The results of physical properties’ data mining indicated that soil saturation percentage, Special Weight and sand and silt percentage, soil texture, surface gravel percentage, and moisture were respectively effective up to 40%, 20%, 90%, 30%, and 100% on the threshold speed. On the other hand, the results of chemical properties’ data mining suggested that the sodium adsorption ratio could be effective up to 90% on the threshold speed. It was also found that organic carbon and organic matter were 100% effective on the erosion threshold rate. However, calcium and magnesium were found to affect the erosion threshold only by 10%. This study’s findings are consistent with those found by Lee (2007), Lee et al. (2008), Mahmoudabadi and Rajabpour (2017), Azimzadeh et al. (2002) and Nourozzadeh Haddad and Bahrami (2015). Physical parameters’ statistical results showed that parameters such as the percentage of gravel, silt, and sand had the greatest effect on the velocity threshold, and that the special weight and clay percentage were least effective in this regard. These findings are consistent with those found by Zare Arnani (2014), Azimzadeh et al. (2004). Furthermore, the statistical results of soil’s chemical parameters suggested that sodium and magnesium had the least effect on wind erosion threshold speed, while the highest impact belonged to the percentage of organic carbon and organic matter, which could be attributed to the high adhesion of soil particles in the presence of organic matter and organic carbon. These findings are consistent with those found by Ekhtesasiet al. (2003), Azimzadeh et al. (2004) and Zahrabi et al. (2019).

As a valuable asset that play a key role in the environment, natural resources, and the production of agricultural products, soil provided an appropriate ground for plant growth and vegetation development. Therefore, any disregard to the preservation of such a valuable capital may result in food shortages, soil erosion, and degradation of natural resources. From among different indices offered for land degradation, soil saturation and salinity are regarded as the main factors involved in desertification. According to the estimates presented by the US Environmental Protection Agency, about 20 percent of the worldchr('39')s agricultural land is under salt stress, and soil salinity is a major constraint on the use of arable land. Meanwhile, soil salinity has rendered many parts of different regions unusable and inappropriate for agricultural activities and natural resources and it is considered as a major problem in arid and semiarid regions. Thus, as more than one-third of the worldchr('39')s soils and much of Iranchr('39')s soils are located in arid and semi-arid regions, it is necessary to take soil salinity into account. In this regard, assessing the environmental potentials could be used a solution for optimal use of soil and water facilities with the least environmental consequences.  Using laboratory methods for estimating salinity is generally time-consuming and costly. Also, due to high spatial variability of soil salinity, it is better to use remote sensing data to determine and monitor saline soils. Considering the importance of the subject and the capability of remote sensing, this technique has been extensively used for studying salinity inside and outside Iran. However, few studies have ever been conducted with eight Landsat images and all salinity indices.  

this study sought to summarize and study all salinity indices used in remote sensing for soil salinity zonation. To this end, using modern remote sensing and GIS software is inevitable. Therefore, as the first step in applying the remote sensing method, spectral indices were used to extract the soil salinity map. For this purpose, after studying salinity indices such as BI, DVI , NDSI, IPVI, SI, SI1, SI2, SI3, SI5, SI6, SIA, SIT, the brightness value of the sampling points was extracted. Based on satellite images, the study region was classified into urban areas (class 1), low salinity areas (class 2), high salinity areas (class 3), mountainous lands (class 4), agricultural lands (class 5). Considering the ability of each of these indices in presenting soil salinity maps, the data were analyzed by SPSS software. Except the EC parameter which was normalized via logarithmic transformation, all other parameters were found to be normal. Having assured of the normality of the data, the correlation between the maps derived from these indices and actual data collected from the area were compared and contrasted.  

Having examined the correlation between the obtained data, it was found that that NDSI and SI3 had the highest correlation with field study data, and that they were the best method for preparing salinity maps without any need to sampling. Moreover, from among the indices investigated in terms of effectiveness, DVI, IPVI, and SI2 were found to have the lowest accuracy in revealing salinity.

The findings of this study indicated that remote sensing techniques were much more useful in preparing soil’s salinity maps than other methods in terms of accuracy and costs. Generally, it could be said that remote sensing is a very powerful tool in soil salinity mapping. Considering the sensor’s low resolution and radiometric accuracy, the fact that salinity changes are not very sensitive and detectable, and that salinity, unlike vegetation, indirectly reveals the waves’ reflections, it should be noted that achieving the best index requires higher resolution images in a wider region so that more significant results could be obtained for defining a regional index. According to the study’s findings, the electrical conductivity of the intended region ranged from 6/11 to 5/5. Ds/m. Moreover, based on soil salinity maps, the southeast lands were found to have more salinity, and that all twelve indices used for identifying the salinity of the region could also be used to distinguish the saline lands. Researchers such as Darwish Sadif et al. (2000), Chitaz (1999) and Abdi Nam (2004) have produced salinity maps using correlation coefficients of spectral values ​​of images and electrical conductivity. Akhzari and Asadi (1395) introduced the NDSI index with 88% correlation as the most appropriate index and identified SI1 and SI2 as inappropriate indicators for soil salinity examination in their study area. The findings of the current study indicated that NDSI and SIT were the best indices in the study region. Moreover, DVI, IPVI, SI2 were found to be the least efficient indices in salinity detection, and that the largest saline area belonged to NDSI and SIT.

Wind erosion results from desertification in arid and semi-arid regions and is intensified by any decrease in rainfall and vegetation. Sistan region, located in southeastern Iran, has been exposed to severe wind erosion and dust storms for about 23 years as a result of frequent and prolonged drought in the region and desiccation of Hamoun lakes. Therefore, finding appropriate methods for reducing wind erosion and controlling dust storms is essential. Using local vegetation is the most efficient method in this regard. This study investigated the reduction rate of wind speed and aeolian sediments within a fourteen-row windbreak in Niatak.

The study windbreak is located in Niatak area in eastern Sistan region. Being located in a dusty corridor, the region is always exposed to severe dust storms. Therefore, to reduce wind erosion and control sediment movement, the area has been re-vegetated. The windbreak is actually one of those revegetated areas. Having been located perpendicular to the prevailing wind direction, it consists of 14 rows of Tamarix tress with a distance of 21-32 m between the row and 1.5 m between each tree on the row. The windbreak’s mean height and porosity were obtained as 4 m and 39% respectively. Moreover, wind speed and aeolian sediments were measured at seven heights and three points, namely upwind (x = -100), within (x = 256), and downwind (x = 448) of the windbreak. Wind speed was monitored during three wind speeds of 14, 16 and 19 m/s and aeolian sediments was assessed throughout three dust storms. Seven anemometers were mounted at the heights of 20, 35, 80, 200, 360, 450, 570, and 700 cm, and seven sediment samples were installed at the heights of 20, 35, 80, 140, 300, 550, 570, and 700 cm. The sand samplers were installed before each event and were collected after the event. They were, then, emptied into labelled plastic bags, taken to the laboratory, and weighed with an electronic balance with a precision of 0.001 g. Standard deviations were measured for aeolian sediments at each point and height.

The study’s findings indicated that wind speed and aeolian sediment were decreased within the windbreak, and that the reduction rates were the same in all wind speeds and dust storm events. This reduction was roughly 30% for wind speed and more than 50% for aeolian sediment at all heights from the ground surface (0.2 m) to about two times the windbreakchr('39') height (7 m). Moreover, the rate of aeolian sediment was higher at downwind (x = 448) than within (x = 256) the windbreak, but less than the rate for the upwind of the windbreak (x = -100). It was also found that the horizontal pattern of aeolian sediment changed from upwind to within and downwind of the windbreak in according to the wind speed variations in all events. Similar to wind speed, a significant breaking was observed in the aeolian sediment patterns, indicating that the windbreak considerably affected wind speed and aeolian sediment in all heights, even in heights higher than its own one. The aeolian sediment’ standard deviation within the windbreak was reported as being less than its value downwind and upwind of the windbreak. Moreover, the standard deviation values at different heights close within the windbreak were found to be close to each other and far from each one upwind of the windbreak. These findings suggested that the deviations of the aeolian sediment values were less within the windbreak than its upwind.

This study investigated the effect of a multi-row windbreak on wind speed and aeolian sediment in three dust storm events and three wind speeds. The study’s findings could be used for designing windbreaks. Moreover, the results of wind speed and aeolian sediment distribution at different heights are applicable to validating wind erosion models, assessing wind erosion and its control. The study’s findings indicated the critical role of vegetation in reducing wind speed, aeolian sediment, and aeolian erosion. It was also found that windbreak reduced wind speed and aeolian sediment in all dust storms and wind speeds, suggesting effectiveness of the windbreak which results from its multi-row structure. Generally, the study’s findings showed that windbreak was able to reduce wind speed and aeolian erosion in various dust storms and different wind speeds. Therefore, it could be argued that multi-row windbreaks are applicable for other regions of Iran that are engaged with severe wind erosion and dust storms.

Desertification is the process of ecological and biological reduction of land potential in a natural or unnatural way, mainly affecting arid regions. Moreover, it decreases land efficiency with increasing acceleration. Land resources and human populations exposed to desertification and land destruction are prone to various threats, including loss of land productivity, food insecurity, water scarcity, economic problems, social deprivation, and health risks. Therefore, the complex and important dimensions of this issue prompted the international community to state at the Rio Environment and Development Conference that one of the goals of sustainable development is to fight against desertification, and to stop and reverse land degradation.   Subsequently, the important role of appropriate and appropriate local measures in dealing with global threats, desertification, and land degradation was emphasized at the United Nations Convention to Combat Desertification (UNCCD). Therefore, considering the limited resources and inputs, the sensitivity of ecosystems in desert areas, increasing success in implementing control plans and reducing the effects of desertification and restoration of destroyed lands, today the evaluation of desertification alternatives is considered as a determining factor in executive projects. Thus, it is necessary to design optimal methods for controlling and reducing this process. Therefore, this case study which was carried out in the Ardekan-Khezrabad plain sought to systematically evaluate optimal alternatives via a group decision model.  

To analyze and present effective alternatives, this study used Delphi method within the framework of multi-criteria decision-making method so that it can consolidate group opinions and use a pairwise comparison questionnaire, followed by a qualitative identification of the most important and prioritized criteria and alternatives. Then the significance of the criteria was estimated via special vector method. Finally, Bernardochr('39')s decision-making method was applied to finalize the alternatives and prioritize them. In the framework of this model, a ranking/criterion matrix was formed for each strategy in order to influence the weight of criteria in the selection of alternatives. The weights of the criteria were multiplied in these matrices based on the relation (1), and an agreement line matrix was formed for each strategy.  (1)  Then, the consensus matrix of the total alternatives was created from the sum of the consecutive line matrices of each strategy. After the formation of the agreement matrix, the total number of times that each strategy ranked in position 1 to k was estimated in the form of a compression agreement matrix according to the relationship 2. (2)     Finally, after influencing the weights of the criteria in the alternatives in the form of a consensual consensus matrix and the formation of an allocation model (Equation 3) for each strategy, the models were solved and the final priority of the alternatives was determined, using Lingo software.    (3)

According to the research literature, the importance of criteria in the desertification process was estimated from a special vector method. The results showed that the criteria of "Proportionality and compatibility with environment" (C7) was at the highest level of importance with a coefficient significance of 0.33877, followed by  "Destruction of Resources and Environmental and Human Damages" (C16) with a coefficient significance of 0.3111, "Expert Human Resources" (C6) with a coefficient significance of 0.1571, " Scientific tools and technology available" (C5) with a coefficient significance of 0.1039, and "time" (C2) with a coefficient significance of 0.9090, respectively, indicating the attention of experts and specialists to environmental issues and challenges in the field of environmental degradation. In general, according to the results of the final prioritization of alternatives, the highest value of the objective functions was found to be 6.7. Therefore, "Prevention of unsuitable land-use changes" (A18), "Modification of groundwater harvesting" (A31), and "Vegetation cover development and reclamation" (A23) were selected as the most appropriate subsets of current alternatives.  

The results of the application of the final prioritization of alternatives based on Bernardochr('39')s method showed that this method was catheterized by flexibility, high efficiency, ease of use, the possibility of using software such as Lingo and EC, and evaluation of alternatives based on a set of effective quantitative and quantitative criteria in-group format. In addition to using multiple criteria for decision making, it considers resource constraints in implementing alternatives or projects, providing an opportunity for decision-makers in the field of natural resources to use the limited facilities and capital allocated to control the desertification process in the right and efficient ways for better results while preventing the waste of national capital.

Soil erosion is the most important factor in damaging and decreasing the productivity of agricultural soils. Moreover, as the transfer of sediments rich in nutrients through the soil leads to soil erosion and in turn to the decrease in the dams’ reservoirs’ storage capacity, bringing about adverse economic and eco-environmental consequences such as damage to land resources and decrease in land productivity, soil erosion is regarded as a serious problem in the world. Therefore, estimation of the soil erosion risk is necessary for preserving agricultural lands and achieving sustainable management of watersheds.

This study investigated the potential and actual erosion risk in Kharestan region, using CIRINE model together with GIS and RS. The parameters are presented as four separate indices. The model consists of the following steps. First, soil texture, depth, and the percentage of stones and pebbles determine the soil’s erodibility map. Second, Fournier and Bagnouls-Gaussen aridity indices which are calculated based on meteorological data would be used to form the erosivity layer. Third, slope classes would be identified according to the DEM of the study area, and then the potential soil erosion risk (PSER) layer is produced through the overlaying of soil erodibility, erosivity, and slope layers. Fourth, the LULC layer is formed based on the Landsat ETM7 images. Finally, the LULC and the PSER layers are combined to identify the actual soil erosion risk (ASER).

The study’s findings indicated that there existed 5 types of soil textures in Kharestan region, including Silty clay, clay lomy, silty clay lomy, sandy lomy, and lomy. It was also found that 75.28% of the study area included clay silty (14.36%), clay loamy and silty loamy clay (60%), and 24.71% of the region comprised of sandy loam and loamy texture. Moreover, three classes were observed for the soil depth of the area, including over 75 cm (60.54%), 25-75 cm (5.92), and below 25 cm (33.53). The findings also indicated that 88.42% of the area was covered with over 10% pebbles, while the rest of the area comprised of below 10% pebbles (plains and hills). In terms of erodibility as a function of soil texture, depth, and percentage of pebbles, 39.24% of the study area was covered by highly erodible soils, while 32.26% of the area was covered by low and 28.48% of it was covered by moderately erodible soil, respectively. In total, about 68% of the study area was erodible. The Modified Fournier Index (MFI) was classified in two classes, the highest value of which was observed in the study area’s class 3, indicating a moderate rainfall. In addition, the Bagnouls-Gaussen Aridity index (BGI) was classified into two classes, with its highest value found in Class 3, suggesting the dryness of the area. Comprised of MFI and BGI, soil erosivity index showed that 60.47% of the region had been located in medium erosivity class and 39.55% of the area had been located in low erosivity class. In terms of potential soil erosion risk, 29.125% of the study area was located in low class, 29.8% in moderate class, and 41.7% in high class. The slope map extracted from the study areas’ DEM showed that 68.38 % of the area was located at slope class of below 15% and 31.62 % of the area was located at slope class of over 15%. The actual soil erosion risk was extracted from the overlap of the potential soil erosion risk and vegetation. Surface vegetation was classified into fully protected (8.71%) and unprotected areas (91.69%). The outcome was a map depicting non-erosion, and, low, moderate, and high actual soil erosion risk in the study area. In terms of actual soil erosion risk, 31.14% of the study area were found to be in low class, 31.11% in medium class, and 37.78% in high class areas. The areas high erosion risk areas within the potential erosion risk map were reduced from 41.07% to 37.78% in actual soil erosion risk map after overlapping the vegetation layer.

Soil erodibility depends primarily on the structural stability of the soil (and hence its resistance to particle detachment by rain-splash or runoff) and its ability to absorb rainfall. As soils with medium to fine texture have low infiltration rates, the are less transferred when exposed to high velocity of runoff water. Moreover, in shallow soils, the rate of erosion increases due to lower potentials for water holding water and higher overland flow. The study’s findings also indicated that the areas with moderate–high erosion risk are located in northern, southeastern, western, and northwestern parts of the region, where the soil and water preservation practices should be focused. Thus, protection and restoration of vegetation in the Kharestan is highly important for the preservation of water and water resources. In the southern, central, and eastern parts of the region, the slope is generally slight and the soil is shallow. However, due to the mountainous nature of the region and the low involvement of human activities, the erosion risks lie in low-class areas. Considering the application erodibility, erosivity, slope and surface coverage, the use of CORINE model for determining the potential and actual erosion risk maps could well show different erosion classes in Kharestan region. Moreover, the study’s findings confirm the application of the CORINE model in natural resource lands. The study suggested that together with GIS and RS techniques, the CORINE model possesses great potential for producing useful and inexpensive erosion risk information in Iran with low data and in relatively short time.

Being located in an arid and semi-arid region, Iran has always faced with limited water resources. As groundwater extraction has now exceeded the permitted limits all over Iran and the country faces considerable constraints in developing groundwater resources, severe water crisis looms large in the horizon. In this regard, a quick solution should be considered to supply water from non-conventional water resources (brackish and saline waters, rainwater harvesting, cloud seeding, etc.). Therefore, this study sought to investigate the status of water in Fatuyeh-Todroyeh plain in Bastak city, Hormozgan province, and the possibility of supplying water from unconventional resources, especially the brackish and saline waters, for agricultural purposes.

In the first step, the required maps of the study area including the groundwater electrical conductivity (EC) map were prepared, using ArcGIS software. Then, chemical analysis of the Fatuyeh-Todroyeh aquifer’s water quality was performed by AqQA software on the data gathered through three rounds of sampling from the wells, followed by the calculation of water quality index (WQI). In the next step, the the study plain’s hydro-climatic balance was measured via Budyko conceptual model, taking changes in storage into account. Then, to investigate the economic justification of using inland water desalination plants in the region, the cost-benefit ratio of the cucumber greenhouse cultivation, and the investment’s return rate for the installation of water desalination plants and greenhouse sites were calculated. Finally, having decided on appropriate criteria and options, the hierarchical analysis method (AHP) was applied for comparing different management options and offering the best plan for supplying unconventional water resources for the agricultural, drinking, and industrial sectors of the study region, using Expert Choice software.

The results of water resources quality surveillance showed that the Fatuyeh-Todroyeh plain’s groundwater samples ranged from acceptable to completely unpleasant in terms of drinkability according to Schuler diagram, and that its dominant water type was something between chloride and sulfate according to Piper diagram. Moreover, based on Wilcox diagram, the suitability of groundwater resources for irrigation purposes ranged from doubtful to unsuitable. In other words, there were no groundwater resources in the plain with low and medium EC and low to high SAR risks. Furthermore, the highest coefficient of variation belonged to sodium ion which was equal to 0.67 over the study plain. In general, according to WQI quality index, 75% of the water in Fatuyeh-Todroyeh plain’s wells have very poor quality, being inappropriate for agriculture and drinking.
Calculations of the plain’s water balance indicated that the decline in storage changes was 2.4 million cubic meters annually, making the development and extraction of groundwater impossible. The results of the investigation of the economic justification revealed that according to the cost-benefit ratio which was found to be greater than one in all years of a five-year period and the investment’s return rate which was greater than the current bank interest rate, the construction of inland water desalination plant and the establishment of greenhouses in the study region is economically justified. The results of AHP calculations suggested that based on the criteria set for unconventional water management in the agricultural sector of the study area, implementing the optimal cultivation pattern was the best choice in this regard, followed by the option of constructing a desalination plant. As for drinking purposes, the highest score belonged to the option of constructing water desalination plants, and for the industrial purposes, the highest score related to the option of prohibiting wastewater discharge into the river protection area.

Conclusion

the study’s findings showed that there were no facilities for the development of groundwater extraction in the region. However, constructing a dam in a suitable place, controlling the rainwater runoff (which is of very poor quality), and desalinating the stored water by a desalination system could help use the plain water acquired for drinking and agricultural purposes in Fatuyeh-Todroyeh plain

Allelopathy refers to the plants’ mutual biochemical effects. Despite their significant role in improving and restoring Iranian rangelands, the plants’ allelopathic effects on each other have often been neglected in rangeland seeding. Scholars argue that in stressful conditions of the arid areas caused by low precipitation, the effects of metabolic chemicals secreted by allelochemical-full plants on adjacent species increase and allelopathy plays a more important role in creating plant communities of natural habitats. Considering the fact that seeding and sowing are considered as acceptable methods of improving and restoring rangelands in potential areas for increasing vegetation in semi-steppe and steppe areas, and that the allelopathic effects of dominant woody species are among main causes of seeding and sowing failure in some regions, this study sought to investigate the allelopathic performance of some woody species including Amygdalus scoparia, Daphne mezereum, and Ebenus stellata on seed germination of their understories species. Therefore, this effect should be identified for the improvement of rangelands in order to provide suitable shrub species for improvement and restoration.

this laboratory study investigated the effect of aqueous extracts of Amygdalus scoparia, Daphne mezerum, and Ebenus stellata on their understories seed germination, using total random sampling with three replications. To this end, some fifteen samples were randomly collected from habitats of Amygdalus scoparia, Daphne mezerum, and Ebenus stellate in the growing season of dominant rangeland plants. The collected leaf samples were dried for 48 hours in oven at 80°C temperature for extraction (aqueous extract). Then the extraction was performed in 1:3 (w/v) ratio on all milled samples. Experimental treatments included aqueous extracts of woody leaves with 1% concentration and distilled water (control). Moreover, distilled water was used as a solvent for performing the extraction in the laboratory (24 h soaking time) which was done in cold water to simulate normal conditions. To increase the contact of the samples’ particles with the solvent, a shaker device was used. To separate the suspended solids from the solvent, cold centrifuges were used at a temperature below 5°C. Then, three petri dishes with a diameter of 120mm and a thickness of 15mm (each container 1replicate) were used for each treatment in which twenty seeds had been put. Having added the solutions, the petri dishes were tapped and placed in a growth chamber under dark conditions at a temperature of 20-25°C and 50% humidity. The seed with two cotyledons was considered as the germinated seed. The collected data were analyzed by SPSS software. Having performed a two-way variance analysis, Duncanchr('39')s test was carried out to compare the means of the significant treatments. Moreover, the Excel software was used for drawing the intended graphs.

this study investigated the effect of aqueous extracts of three woody species and the control treatment on germination rate of understories plants at 5% probability level. The results indicated that there was a significant difference (P <0.05) between the mean of different species’ germination in most cases. It was also found that the aqueous extract of Amygdalus scoparia had decreasing effect on Medicago radiate, Alyssum sp. Ziziphora tenuior L, the aqueous extracts of Daphne and mezerum Ebenus stellata reduced germination of Astragalus podolobus Boiss, Alyssum sp., Bromus tectorum, and Amygdalus lycioides, respectively. The results also showed that the aqueous extract of Amygdalus scoparia had the greatest effect on the germination of the species of Sterigmostemum longistylum Boiss, Clypeola aspera L.,Lolium perenneL. Moreover, the aqueous extract of Daphne mezerum increased germination of Amygdalus lycioides and Ziziphora tenuior L., while the aqueous extract of Ebenus stellata  only increased Astragalus podolobus Boiss germination. Furthermore, it was revealed that the aqueous extracts of Amygdalus scoparia, Daphne mezerum, and Ebenus stellata had no significant effect on germination of rangeland species (Bromus tectorum, Astragalus podolobus Boiss,Amygdalus lycioide), seeds of Sterigmostemum longistylum Boiss, Medicago radiate, Clypeola aspera L., Lolium perenneL., Bromus tectorum, Alyssum sp), and seeds of Sterigmostemum longistylum Boiss, Lolium perenneL., Medicago radiate Clypeola aspera L., respectively.

according to the study’s findings, the aqueous extracts of the three woody species and the control treatment had different inhibitory effects on germination and seedling growth of the understory species. However, it could generally be said that the understory species experienced the highest germination rate under the control treatment. In some cases, the aqueous extract was found to have decreased the germination rate, which could be due to the Artmisian active biologic properties as a toxic Sesquiterpene lactone and has a n inhibitory effect. As the woody species investigated in this study were mainly found in mountainous areas with sandy-loamy texture, it can be argued that in areas where these woody species are dominant, the leaching of understories may reduce their inhibitory effects in comparison with those of the understories’ ones. Therefore, woody species do not have any allelopathic effect at low concentrations on germination of their understory rangeland seeds, and that was why they were abundantly found in the growing season of the rangeland plants under study. Some researchers argue that geographic aspects could also contribute in decreasing the species’ allelopathic effects on seed germination, with the northern aspects having less inhibitory effects than the other directions. soil temperature, and the amount and intensity of light and intensity may cause meso-climatic changes. Therefore, as the germination stage is a critical stage in plants growth and early growth stages play a very effective role in plants establishment, choosing the appropriate cultivar type can guarantee the success of germination and seedling establishment under different environmental conditions. Thus, in restoration projects compatible species should be used. Generally, it could be argued that plant species may exert different effects on vegetative characteristics of habitats in arid and semi-arid climates. So, knowing the type and extent of such effects is necessary for managing, improving, and developing the rangelands.

With thirteen critical erosion hubs containing an area of roughly 532 thousand hectares, and 14 regions influenced by wind erosion with an area of 1144311 hectares, the Yazd province ranks fifth among the Iranian provinces in terms of the magnitude of crisis hub, and third in terms of the extent of affected areas. The history of desertification activities in the province dates back to 1970, based on which some 42,000 hectares of the Yazd-Ardakan plain has been afforested. As a phreatophyte member of the Chenopodiaceae family, Haloxylon aphyllum is mainly characterized by such features as xerophyteness, halophyteness, and psamophyteness, and is considered as the most compatible species among desert plants. On average, each mature Haloxylon aphyllum tree needs 2.4 m3 water annually for optimal growth. This study sought to evaluate and identify the strengths and weaknesses of the Haloxylon plantations carried out with ripping method in arid region in an attempt to fight against desertification. The annual precipitation rate in the Ashniz Meybod Desert rangeland was estimated to be 74 mm, and the vegetation was found to be less than 2% before Haloxylon plantations. The region’s soil has a medium block structure up to a depth of 30 cm and is structureless from the depth of 30 to 120 cm, and its stability in a dry state is very tough. The soil texture in this horizon is clay-silty. The maximum depth of the area’s ripper is 80 cm, and hardpan layer is not completely eliminated. Moreover, during the 1990s, ripping operations and Haloxylon plantations was carried in the study area where 250 Haloxylon trees were planted in each hectare within three years in the water distribution plain and irrigated 12 times.  

This study investigated the Haloxylon aphyllum plantations in the region mentioned. To this end, four transects (300 M) were randomly – systematically considered in each area, on each of which some fifteen plots (10 m2) were randomly collected. For each plot, the vegetation characteristics including the total percentage of vegetation, density, Haloxylon and Artemisia species’ canopies, harmony, and richness and diversity of species, and soil characteristics including Permeability‎ and carbon sequestration, were measured. Moreover, to study the harmoniousness, richness, and diversity of species, the Sympson, Hale, and Margolf methods were used respectively. In addition, to measure the soil’s permeability and moisture, Double Cylinder and TDR methods were used, respectively. The collected data were examined in terms of normality via Shapiro-Wilk test, and analyzed through one-way variance and Dunken tests. As for the inventory, the transect-plot method was performed systematically-randomly. Therefore, for preparing the inventory of the region’s vegetation, eight transects and one-hundred and twenty 10 square meter-plots were used. Moreover, eight and sixteen measurements of the soil’s water permeability and carbon sequestration were made in each site and the whole area, respectively. Furthermore, each season’s soil’s moisture was measured eight and sixteen times in each site and the whole area, respectively, leading to 24 and 48 measurements for the three seasons in total.  

The study’s findings showed that the ripping operations and Haloxylon plantations with a density of two hundred trees per hectare increased total vegetation by 1.87 percent, Haloxylon canopy by 1.68 percent, and the Haloxylon density by 83 trees Per hectare. It was also found that ripening operations had no significant effects on the Artemisia’s density and canopy as the region’s dominant species, and the richness, diversity, and uniformity indices. The pits made following the ripping operations for seeding have led to the accumulation of the surrounding wastewater inside the pits, with the soil moisture in the ripping operations site being 4.25% greater than that of the control site in May. Moreover, the ripping operations have increased the soil’s permeability and carbon sequestration by 0.75 cm per and 1.31 tons per hectare, respectively, which are not significant.  

As ripping operations up to a maximum one meter cannot eliminate the hardpan, the implanted seedlings cannot develop their roots in the soil not be able to take root and would only remain survived and fresh so long as they are irrigated. On the other hand, continuous irrigation to maintain the current situation would be very costly and economically unjustified. Therefore, due to low precipitation rate, inappropriate distribution, and frequent droughts in arid and desert regions, and the high costs of preparing the ground, provision of seedlings, plantation, and irrigation, the attempt to implement the Haloxylon plantation operations with high density for three consecutive years based merely on the region’s precipitation whose maximum ecologic capacity comprised of 1.87% vegetation with regard to the climatic and adaptive conditions of the study area, seems really unusual and.

effective management and protection of wildlife populations depends on human understanding of the relationship between wildlife populations and habitats. The destruction and fragmentation of habitats reduces the living area of local communities, limits them to small habitats, and isolates wildlife populations, leading to increased intra-reproductions, reduced genetic diversity, and eventually the increased risk of extinction in the long run.  Therefore, habitat optimization modeling techniques have been developed based on the analysis of the relationship between species and habitat to determine the range of species’ distribution and habitat suitability which is required for the preservation and management of populations, especially the endangered species. The Gazella subgutturosa is currently protected by the Iranian organization for environmental protection and placed as the vulnerable class in the Red List of IUCN. Characterized by special natural features, Monteh Wildlife Refuge is regarded as one of the best protected habitats for Gazella Subgutturosa. In fact, it is considered as one of the richest habitats in the Middle East in terms of wildlife diversity and the high number of animal species living there, making this biologic field seem much more important. This study sought to evaluate the Gazella subguruttosa’s habitat in Moteh Wildlife and present a desirability model in this regard, trying to identify optimal habitats for Gazella subgutturosa in the region, determine the factors involved in the desirability of such habitats, and discover its limiting and threatening factors. The Gazella subgutturosa habitat threatened the area. Thus, to reduce the interference of human activities with the wildlife activities, it is necessary to identify and preserve areas that are more important in terms of preservation by preparing a map of habitat desirability. This helps identify the most destructive and threatening factors to the habitat and target species, and prevent the reduction of the target population by controlling and eliminating such factors.   

with an area of 205,000 hectares, the Moteh Wildlife Refuge is located in the northwest of Isfahan province, having a cold or semi-arid cold climate. Having surveyed the region in spring, summer and autumn of 2018, this study recorded the presence points of Gazella subgutturosa species in Moteh Wildlife Refuge via direct and indirect observation (the dung and footprints), using the Global Positioning System. Following the review of the related literature and interviews with experts and Moteh Wildlife Refuge’s park rangers, 12 variables were identified, all of which were analyzed in terms of correlation with each other before starting modeling. As for analyzing the data correlation, six environmental variables including maps of distance from rangelands, slop, distance from waterways, distance from agricultural lands, distance from main roads, and distance from mines were selected. The map the desirability of Gazella subgutturosa habitat was, then, developed based on the presence points of the Gazella and environmental variables, presented in two classes of desirable and undesirable. Moreover, the MaxEnt model was validated via the area below the curve which shows the probability of discernment between the points of presence and absence of a model.  

According to the results of the response curves, Gazella subgutturosa prefers areas far from mines and agricultural lands which are near water resources and rangelands, and areas with low slope. The level below the curve was found to be 0.92, indicating that the model worked well. According to the table obtained from MaxEnt, the most important factor in selecting the Monteh wildlife Refuge as the Gazella subgutturosa habitat is its distance from the rangelands, with 33.3% contribution and 36.3% effect coefficient, with the habitat’s desirability considerably decreasing with an increase in distance from the rangelands, followed by slope, waterways, agricultural lands, roads, and mines as other variables involved in this regard. The Jack Naifchr('39')s chart shows that distance from wetlands alone greatly contributed to modeling. The results of the classification of the habitat’s desirability model show that 40240 hectares, equivalent to 19.7% of Monteh Wildlife Refuge are classifies as desirable in terms of the Gazella subgutturosa habitat’s desirability, and 164102 hectares, equivalent to 80.3%, are placed in the undesirable class.  

In this study, the AUC value was found to be 0.92, indicating a very good performance of the model. Moreover, distance from the rangelands was identified as the most important factor in the desirability of the Gazella subgutturosa habitat, with the habitat’s desirability considerably decreasing with an increase in distance from the rangelands. The findings also suggested that Gazella subguruttosa prefers areas near the rivers. The results of other studies also indicate the high importance of water resources for Gazella subgutturosa species. In general, monitoring and careful management of water resources, preventing the advancement of mines, and controlling the entry of domestic livestock to prevent the destruction of regional vegetation are some important measures that should be carried out in managing the habitat of this species.ش