نشریه مرتع و آبخیزداری
سال هفتاد و دوم شماره 3 (پاییز 1398)

The present research aims to investigate the effect of temporal succession on the biological operation of planting Haloxylon persicum on the functional characteristics of rangelands in Khaf County. Three rangelands in which H. persicum planting operations were performed at different ages of 10, 20 and 30 years, and the control area were selected. Sampling along 3 transects of 100 meters, located 10 meters apart, were measured and analyzed for each area and a total of 12 transects. Using the function analysis method, three characteristics of stability, infiltration and nutrient cycle were measured using 11 soil surface indexes. The results showed that there is a significant difference between the succession times for biological restoration from the functional point of view (P <0.01). The highest degree of stability and infiltration is related to the H. persicum range of 30 years old and the smallest of it belongs to the control area. There is a significant difference between the biological regeneration time of H. persicum planting and the control area in terms of nutrient cycle index (P <0.01). The highest levels of nutrients are related to the 30-year-old H. persicum, 20-year-old H. persicum, 10-year-old H. persicum, and the control area. In general, the results of the present study indicate positive biologic effects on the characteristics of the rangeland function, and these positive effects are evident in increasing the functional indexes over time.

Land use changes can significantly affect the hydrology of a forest watershed. Ground cover is important to protect the soil against erosion. Timber harvesting has been changed the canopy cover and forest soil was exposed to the wind and water. Soil compaction and removing the forest floor in the skid trails was reduced the capacity of water absorption in mineral soils and thus reduced water infiltration, increased runoff, which caused to soil erosion. In order to measure the rate of sediments in two slopes and to study the effect of skid trails on the amount of sediments, the plot-level study was carried out in the Gorazbon district in Kheyrud forest in the control area and skid trail after skidding operations in the sample plot. The results showed that the most sediment value was 1.938 g. liter-1 in the skid trail with a 20-40 percent slope in the autumn and the lowest deposition was 0.103 g. liter-1 in the control area with a slope of 20-40 percent in the autumn. Type of Coverage (skid trail and control area), the season and the interactions between the cover and the season statistically have significant effect on the sediment yield, but the slope and the interactions between the slope and cover, as well as the interactions between the slope and season have no statistically significant effect on the sediment yield. Duncan’s test showed that there was a yield statistically significant difference between sediment yeild in different seasons and the autumn had the highest sediment

Resource management governing as one of the most valuable nature resource of watersheds with the involvement of local beneficiary to participatory management of water resources, one of the requirements of the water security program. So we considered social network analysis as an approach to analyzing the relationship between local stakeholders for sustainable management of water resources. The purpose of this study is study social network of local stakeholders using social network analysis in watershed of Kharve Olya of Neyshabur city. This study has been made based on trust and participant links and using quantitative and mathematical indicators in network macro-level (density, concentration, links reciprocity, transferability of links, the average geodesic distance). The results show that social capital degree based on trust and participant links was strong and stability and balance of network is evaluated at the upper limit that indicates a high level of mutual trust and participant among the local stakeholders. Also the correlation between trust and participant links based on QAP index was 66% and upward average. Results of mean geodesic distance index based on trust and participant link trust indicate trust and participant flow rate is from moderate to high degree. The results can be argued that high levels of social capital and unity among people lead to increase trust and participant flow rate among stakeholders so we can accomplish successful governing of water resources at the less expense and time.

This study aimed to investigate the effects of livestock grazing intensities (lenient, moderate, heavy and no-grazing) on herbaceous plant species composition and diversity (grasses and forbs) in understory of Quercus spp. and Pistacia spp. forest in Kebirkouh Mountain, Darehshahr city, Ilam Province, Iran. Vegetation sampling was carried out with randomized-systematic method at flowering time of the dominant plant species in April 2017. Within each quadrat, number of species, name of plants, density, life form and palatability class were recorded for herbaceous plants. Species diversity with the Simpson’s and Shannon-Weiner indices, species richness with Margalef and Menhinick indexes, and evenness with Peet and Sheldon indices were calculated in Ecological Methodology software version 6.1.4. The highest value of Simpson index for grasses and forbs was 0.972 (moderate grazing) and 96.95 (exclosure). Also, the highest value of Shannon index for grasses and forbs was 4.51 (heavy grazing) and 4.56 (heavy grazing), respectively. The highest richness of grasses and forbs was observed in grazed area with moderate intensity and no-grazing area, respectively. In the area without grazing, the richness of forbs was 4.4 and 2.75 according to Margalef and Menhinick indexes. The values of the Margalef and Menhinick richness indexes for grasses in grazed area with a moderate intensity were18 and 15 percent higher than the grazed area with heavy intensity. Peet and Sheldon evenness indexes were the highest for grasses and forbs in heavily grazed area and the lowest for grasses in the moderate grazing intensity and for forbs in the exclosure.

Water is one of the major sources of development in countries and one of the greatest challenges of the present century, which can be the source of many of the positive and negative developments in the world, and in fact destruction of water resources is the destruction of the foundations of development. Researches has shown that improved management of conservation, exploitation and distribution of water resources is possible by reducing Governmental Entrepreneurship and stakeholders' participation and community participation through participatory management. Accordingly, social network analysis is considered as an approach to analyzing the relationships of local stakeholders for sustainable water resources management. The purpose of this research is to survey social network of local stakeholders using social network analysis in Sadr Abad village in Nodoushan catchment of Yazd. This research has been done on the basis of two connections of trust and participation using network level and subgroup level indicators. The results indicate that the degree of cohesion and social capital is moderate, and the stability and equilibrium of the network is also high, which indicates the high level of transmission in the relationships of trust and participation. Also, the correlation between the two connection of trust and participation, based on the QAP index, is 64 percent and it is appropriate and high level. Water management network in Sadrabad has the potential of greater cohesion and social capital, that prerequisite of it is to utilize the appropriate state of trust to increase participation.

Many regular visits were done to investigate the phenological stages of the plant in Zabol and Saravan habitats. Plant cover of the species was investigated by plot with 4 square meter along to 4 transect with 200 meters. To investigate their physicochemical properties of soil, soil sample were taken from 0-30 cm depth under the species and area without species. Forage quality index was analyzed by 4 replication on three phenological stages (vegetative, flowering and maturity stages). Results indicated that the first leaves of the species were initiated in March and August is the end of growing period. The average of canopy cover and density of Citrullus colocynthis had significant difference in the two regions (P<0.01). The rooting depth of this species was 207 and 123 centimeters in Zabol and Saravan habitats, respectively. The results showed that the electrical conductivity, carbon and organic matter under the studied species were significantly higher than the control area. The results of soil analysis under the species of two habitats also showed that sand, silt, acidity, lime and organic carbon content were significant at 5% level (p <0.05) and organic matter was significant at 1% level (p <0.01). Also, the average of sand, acidity, organic creatinine and organic matter of Zabol habitat was higher than Saravan, but the amount of silt and lime in the plant cover was higher in Saravan than that of Zabol.

Knowing the amount of runoff and sediment generated from different lands is an important step in land use management. Since it is not always possible to measure these values, modeling parameters, will be a way to achieve watershed comprehensive management. Beheshtabad watershed in Chaharmahal & Bakhtiari province with different land uses such as range land, agriculture, gardens and urban area is an important part of Northern Karun Basin. In order to simulate the amount of runoff and sediment generated in different land uses, SWAT model was used. Discharge and sediment data of weather and hydrometric stations located in the area was used for sensitivity analyses and then to calibrate and validate model by SUFI-2 algorithm. NS and R² coefficients obtained for runoff calibration are respectively 0.69, 0.71 and for runoff validation are 0.65, 0.67 and for sediment are 0.72, 0.73 in calibration, and 0.66, 0.71 in validation, that confirmed model ability to accurately estimate of flow, runoff and sediment in the study area. The results showed that dry farming lands with average runoff and sediment of 190 mm, 24.5 tons per hectare per year respectively, has the highest and gardens with an average of 80 mm runoff has the lowest sediment yield of 1.63 tons per hectare in the year.

Given the time/cost inefficient nature of land mapping for monitoring of the changes in the earth dams’ body across the world, the Radar Interferometry is introduced here as a modern alternative method. In this study, to investigate the changes in the Taleqan dam’s body, we employed the GMTSAR software and processed 68 Sentinell- A images taken in the time period of 2014-2018. Additionally, utilizing the radar interferometry in the short range, the time series was determined. The time series results implied that the maximum dam subsidence is 3 mm/y along the line of sight. To justify the changes in the Taleqan dam’s body, some studies were carried out on the rip rap of the dam’s body. The obtained results implied that the changes have been caused by erosion and weathering. Due to undesired diffusion coefficient and low resistance of the stones with external volcanic and reolithic structure, such material collapsed under the influence of atmospheric and temperature factors, leading to displacement in the downstream. The performed investigations implied capability of the radar interferometry in monitoring of the earth dams and critical structures and providing information that can play a vital role in analysis of the dams’ behavior and completion of the precise tools measurements.

In Collaborative management of arid regions, it is necessary to analyze the social relationships between farmers. The purpose of this study was to evaluate and analyze the social network of farmers in trust links and to participate in irrigation, marketing and cultivation activities in three villages of Aryan, Hareth Abad and Robat Sarpush in Sabzevar. For this purpose,in the firstusing with qualitative studies of survey approach,direct observation method and target population interview were identified. Then, the quantitative network analysis method, four important indices consist of "density", "reciprocity", "transitivity" and "average geodesic distance" in the links of trust and participation in agricultural activities of the farmers' network were evaluated. According to the results, the density of the four transplants was higher in Aryan village than the other villages, which is indicating more social cohesion in this village. The results of reciprocity and transitivity indexed in the studied links show more balance, equilibrium and stability of the network in Aryan village than the other villages, thus there is more social capital in this village. The average geodetic distance results also indicate the most favorable geodetic distance among the farmers in Aryan village. Increasing the cohesion and solidarity of these villages will speed up the flow of information and exchange, as well as increase social capital in them, and will help people to coordinate and access each other with less cost and time. Therefore, reinforcing trust and social participation is essential for increasing social capital as a necessity for participatory management