جستجوی مقالات مرتبط با کلیدواژه « بهره برداری » در نشریات گروه « کشاورزی »

Gaps affect the soil and other ecological features by affecting the amount of light inside the forest. In this study, the effect of natural and artificial gap of mixed and pure stands of Fagus oreintalis on the physical and chemical properties of soil was investigated. For this purpose, 24 trees in the mixed type and 24 trees in the pure beech type were selected in the Hajikola-Tirankoli forestry project from the Tajan river watershed, in 2015. These gaps are classified into three classes: small (less than 150 square meters), medium (between 150 and 350 square meters) and large (350 to 500 square meters). In each gap, 5 plots were made on the diameters. Inside each plot, a soil sample was prepared from a depth of 0-30 cm and a composite sample was prepared. In addition, a control soil sample was also prepared outside each gap. The gap size had a significant effect on pH, EC, potassium, carbon, nitrogen while, the type of stands had significant effects on organic matter and nitrogen (P<0.05). Also, the interaction effects of gap size and stand type had significant effects on nitrogen, organic matter (P<0.05). The highest amount of potassium was observed in large gaps (with an area of ​​350-500) in pure beech stands and the lowest in mixed stands. The results of the present study showed that the amount of carbon, organic matter, nitrogen and potassium increases with the increase of the gap size. In the gaps resulting from cutting (artificial), the highest amount of nitrogen was observed in the large gaps of pure beech mass. There was more organic matter in the large gaps than the small ones. Also, the gap size and the stand type had no effect on the amount of phosphorus in the soil. Therefore, it can be said that in the mixed stands, especially in large gaps, soil fertility is higher than in small gag in pure stand.</span></span></span></div>

According to the law on the protection and exploitation of forests and pastures, any exploitation of natural resources by natural or legal persons must be done with the approval and permission of the country's natural resources and watershed management organization. Issuing grazing and grazing permits is one of the most important permits in the natural resources sector, which has its own implementation process. The evidence shows that there are various issues and problems in the process of issuing this license, and it is necessary to conduct a pathological scientific investigation to improve and correct the said process. The aim of the current research is to identify and categorize the existing damages in the process of issuing and renewing livestock grazing permits in pastures. 

This research is qualitative in nature and the technique of interviewing with focus groups has been used, in this research 96 beneficiaries and 31 experts from 6 provinces of Kerman, Isfahan, Hamadan, Kurdistan, Mazandaran and Semnan were purposefully selected and their opinions about the process and issues of livestock grazing licensing were analyzed using questionnaires and interviews, and the results were collected and analyzed using the content analysis technique.  

The results of this survey led to the identification and confirmation of 30 types of damage and problems in the process of issuing and renewing livestock grazing licenses in the form of three main categories (systemic, legal, and structural-executive), which in the branch of systemic problems, the component of multiple systems and the lack of a system integrated and intelligent, in the branch of legal obstacles, the component of time-consuming investigation of legal violations of applicants for grazing license renewal, division of grazing license among the children after the death of the owner of the grazing license, and in the branch of structural problems, the component of the weakness of monitoring and monitoring systems, lack of update of livestock and pasture statistical information , the low motivation of audit experts of natural resources departments and the lack of provincial credits have played the biggest role in the process of issuing grazing permits. Based on the results of this study, the issuing process in the investigated provinces takes 15 steps and 73 days, and the process of renewing the license is done in 8 days. 

In a general formulation and based on the findings and considering the problems that were stated before, in order to improve the process of issuing and renewing the Kera license, there is a need to take measures, for this purpose, it is necessary to create an integrated system, optimize the notification system, and automatically renew. Grazing license should be prioritized for responsible livestock farmers, updating information on livestock, pastures and determining the exact boundary of pastures and correcting or removing disturbing rules and instructions.

According to the law on the protection and exploitation of forests and pastures, any exploitation of natural resources by individuals or legal persons must be done with the approval and permission of the country's natural resources and watershed management organization. Issuing a license to exploit medicinal plants is one of the most critical natural resource licenses. It has an implementation process. The evidence shows that there are various issues with issuing this license. It is necessary to conduct a scientific investigation to improve and correct the mentioned process. The upcoming research analyzes the licensing process for medicinal plants in the field of natural resources.

The current research is qualitative and applied. In order to identify the current status of the sadro process and the license to exploit medicinal plants, the qualitative research method of the focus group has been used. This research selected 64 users and 30 experts from 6 provinces. Their points of view were collected and analyzed using content analysis.

The results showed that, in total, there are 23 harms in the process of exporting the exploitation of medicinal plants, which are the multiplicity of systems and the lack of an integrated and intelligent system, the lack of a common platform for the implementation of processes in the provinces, the physicality of performing a large part of the processes, unauthorized harvesting and No product license from the plantations, lack of specialized manpower for monitoring, handing over the right of exploitation to non-native people, neglect of some observers in declaring and including the actual amount of production and harvesting of medicinal plants, the small financial and economic power of the operators to prepare the plan booklet, the largest share in the pathology of the licensing process. Also, the results showed that the average time required to obtain a license with a design booklet is 16 months. Without a design booklet, it takes 67 days. This time to get a license to transport the product inside the province was estimated to be 17 days on average and 23 days outside the province.

Issuing a license to harvest medicinal plants is one of the most critical licenses in the country's natural resources sector, which has its implementation process. There are various issues and problems in issuing this license, leading to problems and dissatisfaction among the users and, ultimately, damage to the rangelands. Therefore, taking measures to improve affairs and reform this process is a fundamental issue that needs to be investigated and proposed a solution. Based on the findings of this investigation, the creation of an integrated electronic system, continuous and regular field monitoring through intrusive intrusions at the various stages of medicinal plant exploitation, especially in the harvesting phase, with the cooperation of the engineering system organization, the priority of the exploitation contract with natives and local communities, and improving the motivation for public sector experts can be effective in enhancing the process.

Awareness of the amount of aquatic stocks in each water source is one of the first and most basic information needed to manage of fishery stocks. The Babylon snail species has commercial and export value and its catch has increased in recent years and has not been studied yet. In the present study, the exploitation status of Babylon snail was evaluated by sampling four fishing areas of this species in the north of the Oman Sea (Iran) including Pasabandar, Bris, Pozm and Konarak from September 2021 to September 2022. Biometric analysis was performed on a total of 2779 Babylonian snail specimens. The mean length (standard deviation) and weight (standard deviation) of total snails were 34 ± 5 in the range of 19 - 64 mm and 12 ± 5 in the range of 2- 66 g, respectively. Growth and mortality indices include infinite length (mm) L∞ = 71, growth coefficient K = 0.35 (yr-1), natural mortality M = 0.5 (yr-1), fishing mortality F = 1.75 (yr-1); Total mortality was calculated Z = 2.25 ± 0.29 and exploitation coefficient E = 0.78. Babylon snails have a recruitment in all months of the year and have two major recruitment peaks during the year. The Production per biomass (P/B) 2.15 ± 0.23 in the range of 2.38 - 1.92 and the average annual production is 12 ± 3 per year in the range of 9 - 15. The present study showed that the exploitation coefficient of this species was not desirable and it should be in order to maintain and sustain fishing of this species, appropriate measures should be considered, including reduction of exploitation.

According to the law of hunting and fishing, the law of protection and improvement of the environment, and the conventions and regulations of the IUCN, some parts of the country are classified as four environmental areas (national parks, national natural monuments, protected areas, and wildlife refuges). By the end of 2021, a total of 309 areas with 18.9 million hectares, equivalent to 11.5% of the country's area, have been approved as four areas, which can be considered in the field of public ownership (Anfal), government, private or a combination of them and be exploited with a specific use. While examining the effect of determining the four regions on the ownership and its documents, the ownership rights and exploitation, the adequacy or inadequacy of the existing regulations that need to be amended or supplemented to the system has been investigated. The relevant executives should follow up their approval process through the Islamic Council or the Board of Ministers, it is suggested as follows:- Adding two notes to articles 2 to 5 and one note to article 12 of the Executive Regulations of the Environmental Protection and Improvement Law.- Adding a note to Article 6 of the aforementioned law.- Adding a note to Article 9 of Hadnagar Law.- Amendment of Note 4, Article 31 of the Law on Protection and Exploitation of Forests and Ranges.The result shows that if these suggestions are applied, the ambiguities and challenges related to obtaining the ownership documents of natural resources located in the four regions and the system of its exploitation along with the problems between the two organizations of Environmental Protection and Natural Resources and Watershed Management regarding judicial and administrative measures, especially issues related to damages caused by public and construction projects in the mentioned areas, will be resolved

Taleghan Dam is the main suplier of water required by the agricultural sector of Qazvin plain. Reducing the amount of water allocated to the Qazvin plain irrigation network and uncertainty about the welfare provided by farmers due to the interruption of the time between the production of the crop and its supply to the market, have caused farmers to seek welfare by reducing fallow and draining groundwater resources. In this study, with the aim of preserving groundwater resources and providing livelihood to farmers, the groundwater level in the irrigation network of Qazvin plain is simulated under six scenarios: 1) Continuation of current harvest without increasing cultivated area 2) Increasing cultivated area by reducing fallow 3) Simultaneous optimization of Cultivation pattern and distribution water with price forecasting 4) Simultaneous optimization of water Cultivation pattern and distribution water with price forecasting and reduction of functional vacuum 5) Simultaneous optimization of Cultivation pattern and distribution water with price forecasting and increasing efficiency Irrigation 6) Simultaneous optimization of Cultivation pattern and distribution water with price forecasting, increasing irrigation efficiency and reducing the yield gap using the system dynamics during the years 2002-2037 in Qazvin plain irrigation network. The results showed that the drop in groundwater level under scenario one and two will be on average 1.2 and 2.4 meters per year. Simultaneous optimization of the cultivation pattern and water distribution with price forecasting in scenario three, four and five droped groundwater level to 1.6, 1.4, 1.3 and 1.2 meters annually, while the welfare of farmers is compensated, too.

Natural resources are the main sources of income for many villagers of country. The diversity of stakeholders in natural resources field, leads to the conflict. Recognition of the effective factors in the conflict between the stakeholders are very importatnt in natural resource management. This study was done in Rural Regions of Southern Ardebil and legal, managerial, exploitation, and social components were examined from the perspectives of both experts and beneficiaries. To accomplish the research, 240 questionnaires were completed in target population. The validity of the questionnaire was 0.96. The Mann-Whitney U-test was used to compare differences between two groups. The results show that in addition to the natural resources conflict in the whole region, in terms of perspective, there is a significant difference between the factors affecting the conflict between the local community and government experts. The most important components for increasing the conflict in this region from the perspective of stakeholders are lack of government support for the operator, cut down trees, people awareness level, and according to the experts, lack of law, early grazing and level of awareness of stakeholders. Land grabbing, Coaling, wood smuggling, and understory tillage aren’t the most challenging issues. From the managerial point of view, both groups have declared that the most effective way to reduce the conflict is the confinement of forests and pastures, but the participatory management issues was not accepted according to the two groups’ viewpoints. Effective presence of experts in the field, recognizing the livelihood potentials of the region, and encouraging and educating people to know alternative jobs are suitable ways to reduce conflict.

Conflict in natural resources arises from the disagreement over the availability, control, and use of the natural resources. This study aimed to identify the effective causes of conflict between stakeholders in natural resources management. In this study, legal, managerial, exploitation, and social components were examined from the perspectives of both experts and stakeholders in the forest watersheds downstream of Sefidrood and Polrud in Guilan province. The research was conducted basd on quantitative and survey methods. The natural resource experts and exploiters completed 173 questionnaires. The reliability of the questionnaire for all categories of items was more than 0.9. T-test was applied to compare the views of the two groups. The results showed a significant difference between the views of exploiters and government experts in terms of the factors affecting the conflict. The most important components for increasing the conflict in this region from stakeholders' perspective are the law-breaking, cutting-down trees, council ownership of pastures, the low presence of women in this field, and low cooperation. According to the experts, lack of laws, lack of rangeland union, non-compliance of watershed management plans with the ecological conditions, and low collaboration between people have been introduced. Both groups confirmed the low awareness of the exploiters, but issues such as early grazing, accumulated livestock, understory agriculture, plowing of national land were not recognized by the exploiters as the causes of rangeland destruction and conflict. Experts also did not confirm the important factors such as land-use conversion and assignments that led to the aggression in the region. In fact, both groups did not acknowledge the factors that could have contributed to the increase in the conflict. From the managerial point of view, both groups have declared that the most effective way to reduce the conflict is the confinement of forests and pastures and cooperative management.

The use of modern irrigation systems due to the increase in efficiency and productivity of water consumption is a basic solution compatible with water shortage conditions. The use of proper irrigation methods to maintain food safety and reduce water requirements is a global issue. The most important goals of the implementation of these systems are quantitative and qualitative protection of water and soil resources and sustainability of agricultural production.

In this study, technical and hydraulic evaluation of seven new irrigation systems (integrated irrigation, Movable Sprinkler Solid-Set Irrigation Systems and Trickle Irrigation) implemented in Shahrekord, Bon and Saman cities in Chaharmahal and Bakhtiari province was performed. To evaluate integrated and Movable Sprinkler Solid-Set Irrigation Systems, Christiansen uniformity coefficient (CU), distribution uniformity (DU), potential application efficiency of low quarter (PELQ), application efficiency of low quarter (AELQ) in two block scales were experimented and the whole system were calculated. To evaluate drip irrigation systems, uniformity indices of water emission throughout the system (EU), potential application efficiency of low quarter (PELQ), application efficiency of low quarter (AELQ) were calculated.

The results showed that the values of CU, DU, PELQ, AELQ indices for the tested block in integrated and Movable Sprinkler Solid-Set Irrigation Systems were equal to 68.6, 59.38, 46.85 and 58.56 and and for the system, 67.01, 58.48, 45.2 and 56.5. Was calculated. Also, EU, PELQ and AELQ index values for drip irrigation system were 55.62, 51.91 and 53.83. The results showed that the above systems have a good infrastructure and most of the problems of these systems are related to the phase of operation and maintenance of these systems by users.

The main problems of these systems that have led to a decrease in performance evaluation criteria are the deficit irrigation, lack of knowledge of users and lack of training on how to use the system properly (pressure regulation, periodic visits to the system, interest Correct and principled removal, etc.), changes in high pressure and uneven distribution in the system, changing the irrigation cycle, using more sprinklers and non-compliance with the proposed cultivation pattern in accordance with the design booklet and the use of drippers are inappropriate. Therefore, according to the comprehensive review, it is suggested that training courses should be given to farmers by changing the type of system from traditional to modern methods, and farms that are optimal in terms of exploitation should be identified and visited by others.

Water stored in the reservoir is one of the main sources of water supply in arid regions. Therefore, optimal operation of it is of utmost importance, especially in drought duration. In this study, optimal operation of Voshmgir dam using continues hedging policy optimized by linear programming (LP) and Partial swarm optimization Algorithm (PSO) that located in Golestan province north of Iran was investigated. The objective function is minimization of the Shortage index. In order to examine the effects of used hedging policy, 3 continuous drought years was considered. To evaluate the results of the models, evaluation criteria such as the percentage of water supply, reliability, vulnerability and stability indicators was used. The threshold volume changes per month was extracted and the base hedging rule curve for reservoir was presented. Evaluating the results of two models showed stability index in linear programming with 41.78 model was much higher than particle swarm algorithm with 6.416. Which indicates the higher performance of this model in the optimization of hedging policy in Voshmgir reservoir.

The impact of logging and tree harvesting on the ecological function and the future of Hyrcanian forests structure is a continuing debate topic. The information is currently available does not support firm conclusions about the impact of forest harvest intensity on forest structure and biomass. The present study aims to evaluate the effect of single-tree selection harvest intensity on biomass of hornbeam-Persian ironwood stand. For this purpose, information on all trees and dead trees were collected in 70 half-hectare plots. The 35 sample plots were in single-tree selection stands with three harvest intensities and the same sample plots were in control stand. Trees litter fall were measures from September to February and the storage of soil organic carbon was determined through organic carbon and bulk density. Then, tree biomass, litter biomass, dead tree biomass and total biomass were finally calculated. The results showed with increasing the rate of harvest intensity up to 13.5% the total biomass had rising trends, although harvest intensity had no significant effect on aboveground and belowground biomass and soil organic carbon. The aboveground biomass was higher in single-tree selection stand than control stand. The average of total biomass was 147 and 144 ton/ha in harvest and control hornbeam-Persian ironwood stands respectively and harvesting increased two percent of mean total biomass. The medium harvest intensity (3.6-9.5% of stand volume) was finally determined as appropriate selective logging intensity. The correspondence of litter biomass and dead tree biomass as bio indicator indicated that tree marking in the single-tree selection system was advisable.

Oriental beech (Fagus orientalis L.) is one of the most important industrial species in Hyrcanian forests which exploited via forestry projects with various methods, including a single selection method since the last half-century. Genetic diversity in forest trees is critical for their adaptation to the new environmental conditions. This study was aimed to study the effect of single selection method on genetic diversity of oriental beech in the forests of the east of Mazandaran province, Iran by comparing two management method in protected and exploited plots using single selection method in Haftkhal Forestry Plan. Paired sampling was performed from the leaves of 60 mature trees in the control and exploited plots. Ten microsatellite primers were used to assess the genetic diversity. The results showed that a total of all 10 microsatellites loci produced polymorphism bands. The amount of heterozygosity was 0.52 and 0.49 in the control and exploited stands, respectively. The frequency of specific alleles in mother trees were 3.75 and 3.19 in the control and exploited stands, respectively. Based on the single selection method, beech trees were not significantly different in the control and the exploited plots in terms of the total number of alleles, specific alleles, allelic richness and heterozygosity. However, the observed heterozygosity was 41 and 45% lower than the expected heterozygosity in the control and exploited stands, respectively. Therefore, based on the genetic parameters extracted from 10 microsatellite primers; it was concluded that the single selection exploited method did not have a negative effect on the genetic diversity of mother beech masses in the studied forests.

Having comprehensive and new information on medicinal and industrial plants distribution is necessary for proper planning, managing and use of these resources. Due to the ecological and economic importance of Ferula gummosa, this study was conducted. Economical evaluation of the species and affecting environmental factors on its distribution were selected as the goal of the study. The study area is located on Lar customary settlement of Shemiranat, Tehran province. At the relevant habitat of the species vegetation were sampled using systematic-random method. Soil samples were taken from 30 cm depth. DCA and Canonical Comparative Analysis (CCA) methods were used to evaluate the relationships between vegetation and environmental factors. The results showed that soil electrical conductivity was the most important factor affecting on the distribution of plants in the study area. Elevation as a factor was also identified as one of the important factors on the distribution of plant. Considering the expected leachate production capacity of the whole study area, i.e., 18 tons/year, net economic value of the species was 16950 million Rials for a one period of operation.

What has been identified as the relationship between natural resources and conflict? In what ways are natural resources used to trigger conflict and instability? Who are the main players and actors in resource conflicts? To address these questions, this article critically reviews the main theoretical and empirical works on natural resources conflict. This area was studied as the target population due to the rich forest and rangelands resources and considering the existing conflicts in the Ardabil province. The conflict of interest between exploiters and natural resource experts is one of the problems that may have remained from the period of nationalization of forests and rangeland (1962) and has become more critical gradually. In this regard, the inapplicability of the laws, the numerous transfers that have taken place over the years, and the lack of transparency of the border between national lands and exceptions, have led to many problems. This study seeks to investigate the reasons and causes of the conflict between the key natural resources key stakeholders including beneficiaries people who use the rangelands or forest and the local authority or national actors (government) over natural resources in the study area.

legal, managerial, exploitation, and social components were examined from the perspectives of both experts and stakeholders. A number of 205 questionnaires were completed by the officials of natural resources of Ardabil and Garmi cities and its stakeholders with the Snowball Method. The validity of the main variables was more than 0.7, which is an acceptable number. Divergent validity index, among all features, was less than 0.9, which indicated that there is no dependence between the variables of each feature. Since the scale of measuring the views of experts and stakeholders is the rating, the non-parametric Mann-Whitney U-test was used to compare the views of two groups on the causes of conflict in natural resources.

The results showed that the natural resources conflict in the whole region, there isn’t a significant difference between the factors affecting the conflict between the local community and government experts in terms of perspective. The most important components for increasing the conflict in this region from the perspective of beneficiaries are lack of expertise of the resolution council, lack of government support for ranches, financial poverty, conflict with rangeland encroachers, low level of awareness of stakeholders, and according to the experts, lack of government support for ranches, lack of law, lack of rangeland cooperative, insufficient water in rangeland, financial poverty, lack of cooperation among the people and migration. Land grabbing, coaling, wood smuggling, and understory tillage aren’t the most challenging issues. From the managerial point of view, both groups have declared that the most effective way to reduce the conflict is the confinement of forests and pastures, but the participatory management issues were not acceptable according to the two groups’ viewpoints. Effective presence of experts in the field, recognizing the livelihood potentials of the region and encouraging and educating people to know alternative jobs are suitable ways to reduce the conflicts.

It seems that the plans of stopping the exploitation of natural resources are more accepted in this region. Participatory management is one of the solutions to reduce the conflict which necessity of its implementation was not acceptable according to the two groups’ viewpoints.

The poor performance of irrigation districts led to the unreliable distribution of surface water among farmers. Therefore, it is necessary to improve the water distribution in the irrigation district. For this purpose, there are two practical solutions, improve operational method and adjustment of estimation of agricultural water demand, each of which has been researched separately. In this study, for the first time, the effect of improving the adjustment of estimation of water demand was investigated by developing and combining AquaCrop model and ICSS hydrodynamic model for Roodasht irrigation district under a water shortage scenario in the status quo. For this purpose, the daily agricultural water demand was estimated for each of the secondary irrigated units based on the cultivation pattern by using the AquaCrop model. After calculating the average daily flow rate to each off-take (the output of the water distribution simulator model in the main canal) the adequacy index was calculated for two conditions, 1) with considering the amount of requirements specified by the network administrator  (available condition) and 2) adjustment of water demand. The results showed that the performance evaluation indicator improved from 3% to 16% for all off-takes by adjustment of agricultural water demand. This improvement has been achieved by reducing the amount of water right in the upstream and middle of the main canal and increasing the amount of water right for downstream. Also, the equity of water distribution has improved among water users by adjustment of agricultural water demand.

a significant portion of water is wasted during the conveyance and distribution process due to seepage and operational losses. To deal with the limitation of water resources, it is necessary to provide methods for reducing losses from canals. Therefore, the current study aimed to represent a method for estimating the minimum seepage and operational losses in earthen canals in order to improve water efficiency in agricultural water distribution systems using ant colony optimization algorithm.

In this research, the innovation and aim are to optimize seepage and operational losses in water distribution system using the ant colony optimization and the results of the algorithm are used to manage water resources, especially in agricultural water distribution systems. To achieve this goal, initially, basic information was collected from the Moghan plain canal and for the purpose of hydraulic flow simulation in the canal a simplified mathematical integrator-delay model was used. Then, in order to minimize seepage losses, a formula extracted from research history was applied. In addition, the seepage formula was calibrated and validated based on the measured seepage amount at each segment over the 23 km of the canal. Also, to optimize the purpose of this study, two single objectives, which they were minimizing seepage and water shortage delivered to each offtake in the main canal distribution process, respectively, were defined and adjusted in ant colony optimization algorithm model. Then, by linking the hydraulic simulator model, the estimation seepage formula and the Ant colony optimization model, it was possible to optimize the mentioned objective functions.

According to the results, optimizing the first objective function, in order to minimize seepage losses caused the reduction of total seepage amount during the 23 Km of selected research area, from 0.199 Cubic meter per second (seepage in the present condition of the studied canal) to 0.187 Cubic meter per second. Therefore, the reduction in seepage losses for the first objective function was 6 percent. However, the application of the first objective function has led to an increase in the amount of operational losses from 39.91%, which is the amount of current operational losses in the canal, to 45.55%. In other words, the operational losses from the first objective function compared to the current operational losses, increased by 5.64%. Accordingly, the total reduction of losses in the first objective function compared to the current losses in the canal was 0.39 percent. By applying the second objective function, the results show a reduction in operational losses from 39.91% to 27.91%, which indicates a 12% reduction in operational losses compared to the current situation of this type of losses. Also, seepage losses have increased from 0.199 cubic meter per second to 0.2168 cubic meter per second, which indicates an 8.9% increase in seepage losses compared to the current situation. Overall, the total losses reduction in the second objective function compared to the current situation is equal to 3.1 percent.

single objective functions of seepage and operational losses reduction results showed that optimization with the purpose of reducing seepage losses did not lead to a significant reduction in total losses in irrigation canals. On the other hand, in order to reduce operational losses, Ant colony optimization algorithm model by choosing optimum water depths could reduce the amount of operational losses to a considerable amount. According to the results, it can be generally acknowledged that modernization, renovation and rehabilitation projects of irrigation networks with the target of reducing losses and improving water use efficiency, if more focused on improving the operating process, more reduction of losses would result in agricultural water distribution system.

Large-head hairtail, Trichiurus lepturus, is one of the commercial fish at the Persian Gulf and Oman Sea waters, which is exploited to export outside markets. To present population dynamics and characteristics of this species, the fish caught by trawling method were analyzed from Kolahi to Dargahan areas in Hormozgan province waters. The von Bertalanffy growth equation (VBGF) was fitted to length-frequency data (n =771) to obtain a VBGF with the following parameters: L∞, K, and t0 were 88.83 cm, 0.10, and -0.07, respectively. The estimated value of total mortality (Z) and natural mortality (M) were 0.44 and 0.28 (year-1), respectively. Also, fishing mortality (F) was recorded as 0.16 year-1. Exploitation rate, corresponding to the maximum relative yield per recruit (E) was 0.36, and this fish in the present study caught capacity. Recruitment pattern showing maximum added yang fishes in September. The present results have to be considered with caution for fisheries management purposes as fishing effort is still in increasing phase. Long-term monitoring is required. To better understand the T. lepturus population dynamic and its fishery framework in the study region.

Mining is considered one of the dimensions of development that human activities affect ecosystems. In land sustainable management (LSM), ecosystem changes that occur in areas during mining -as one of the appropriate measures to determine the ecological vulnerability- is very important. In the present study, based on ecological sustainability, environmental degradation model of Tabas city were evaluated and classified. In this regard, a set of environmental factors including topography, vegetation, climate, groundwater, soil, and geology data layers were prepared using satellite images and stationary data. According to the results, environmental factors of topographic, precipitation, and vegetation have the highest sensitivity, respectively. According to studies, mines accounted for 15.3 percent of the study area. Most exploratory mines were classified in a semi-sensitive class. Soil and geological (edaphic) factors with the highest ecological limitation were more diverse than other factors in this region. Accordingly, due to the high sensitivity of the soil and the possibility of erosion, especially in areas with low vegetation or barren lands in eastern and southwestern areas that have more vulnerable, should be less priority in mining activities.

Over the past several decades, most of the world’s ecosystems have experienced a sharp decline in the population of commercially valuable fish. The aim of this study was to provide integrated information on the biology, ecology and population of the black- mouthe croaker population for sustainable harvesting and conservation of species diversity. According to studies, of black mouth croaker with scientific name of Atrobucca nibe(Jordan & Thompson, 1911) is one of the endangered species, while new deposits of this species have been reported in the waters of the Oman Sea. Preserving the reserves of this species with an emphasis on economic sustainability is becoming more and more apparent.However, since the identification of these reserves, this goal has not been fully achieved due to the non-continuation of commercial experimental fishing by the National Fisheries Organization. Iran's waters are inconsistent with each other, and numerous investigative and commercial studies of the black-mouthed species must be continued.

The water shortage and the recent droughts have revealed the necessity of paying attention on increasing the water productivity, more than done in the past. In this regard, using pressurized irrigation systems is recommended as alternatives for surface irrigation systems. So this study, in order to assess the system performance and water productivity in such systems, nine and ten of the existing sprinkler irrigation systems (constant classic and wheel move) were evaluated in Isfahan and Hamedan Provinces, respectively. The Potential and the actual application efficiency of the low quarter, the distribution uniformity and the Christiansen's coefficient of uniformity were determined. The Averages of PELQ, AELQ, CU and DU in Isfahan province were 61.5%, 58%, 66.8% and 75.8%, respectively and those of Hamedan province were 53.9%, 44.8%, 71.1% and 81.1%, respectively. By determining the average of water consumption and the crop yield, the averages of water productivity in Hamadan and Isfahan provinces were found 6.6kg.m-3 and 6.3kg.m-3, respectively. The averages of water consumption in the irrigated potato fields in Hamadan and Isfahan were 6745 m3/ha and 6298 m3/ha, respectively. The results of this study showed that in most of the studied fields, deficit irrigation has been happened. From the results of these assessments, it can be deduced that the main problems in the implementation of these systems are: inaccuracy of design, the mismatch of design criteria with the implementation phase, incorrect performance, insufficient users' knowledge and the lack of accordance between the amount of water used and the crop water requirement.