نشریه مرتع و آبخیزداری
سال هفتاد و سوم شماره 2 (تابستان 1399)

The aim of this study was to identify factors influencing participation of landholders in the the rehabilitation and restoration of Choqakadoo rangeland in the city Sarpolzahab province of Kermanshah The aim of the research, applied research methodology, causal correlation. In addition to data processing descriptive statistics and correlation, multiple regression and path analysis method of inferential statistics were used. The results showed that the correlation coefficient attend public hearings, cordial relations with its neighbors, dominating the promoters on technical topics, providing extension services in the field of rehabilitation and restoration of rangeland, over responsibility for part of the program into landholders, membership in local organizations, familiar of landholders with and participate in training courses and promotional programs most of solidarity with the participation of landholders in the rangeland rehabilitation and restoration. Enter regression methods on variables including background indicate that their level of education, the most direct and positive effects (0/281) and the most positive effect and total (0/357) on the participation of landholders, also number of livestock, number of dependents and income are next in priorities. Among the variables including background age and years of exploitation has a negative effect (-0/482 , -0/468) on landholders' participation in the rangeland rehabilitation and restoration. So pay particular attention to these factors can be placed on the agenda of managers and planners and more participation of landholders in areas of rehabilitation and restoration of rangelands, provide in every area.

Prediction of rangeland species forage yield is one of the most effective tools for planning and policymaking of natural resources in each country. Climate variables (precipitation and temperature) play an important role in forecasting rangeland species production. In the present study, the forages yields of some typical species in Ghoosheh rangeland, Semnan, measured using cutting and weighing method. It was evaluated in 30 plots with an area of two square meter, distributed along with two transect lines, for a 10-year period (water year 2005-2006 to 2014-2015), to determine the effects of drought on the forages yield of typical species in the studied areas. In the next step, several drought indices were calculated. The relationship between forages yield of rangeland species and drought indices values investigated to model forages production of study areas via drought indices. According to the values of drought indices SIAP, PNPI and Z-Score, several drought and wet-year periods occurred during the assessed 10-year. The relationship between forages production and drought indices confirmed that the best simple linear regression model for estimating total forages production of studied area was introduced by SIAP and Z-Score indices (RRMSE = 0.1) explaining 53% of production changes at 95% confidence level. The effects of drought and wet-year periods varied among different species so as to the annual production varied greatly for annual species (between 1 and 11% of total annual forages yield) and slightly for perennials and shrubs.

Thyme is one of the most important medicinal plants in the world; some of its species are native to Iran. Given the necessity of thyme preservation and development, the vegetative climatic needs of this plant were addressed in this study. To this aim, 52 climatic parameters influential on the thyme growth were considered in 30 meteorological stations located in Isfahan province and the neighboring provinces. Factor analysis with varimax rotation was then conducted to determine the most important factors influencing the growth of thyme. Determination of the climatic zones of the thyme plant was done using hierarchical cluster analysis, leading to the identification of five climatic zones; according to effective climatic parameters, these included the cold and rainy zone, the semi-arid and cold zone, the dry and windy zone, the arid and cloudy zone, and the dry and hot zone. Cooling temperature factor, with a mean of 2.55, had the most positive effect, while the wind factor, with a mean score of -0.28, had the highest negative impact on the distribution of thymus species in the zones with this species. The precipitation factor, with a mean score of 0.8, had the second rank in the zone that could be suitable for the growth of thyme species. Overall, cooling temperature and precipitation could be regarded as the most important factors in determining the growth and distribution of this species; these factors could have a positive effect in rainy and cold zone and the semi-arid and cold one.

The present study has been carried out aiming at suitable site selection for rainwater harvesting across the northern rangelands of the Aq Qala district to supply drinking water for grazing livestocks using the effective criteria and multi-criteria decision support system. The rainwater harvesting suitability map was created by integrating the multi-criteria evaluation (MCE) technique and standardization (fuzzification) of continuous raster data within ArcGIS. To determine the suitable rainwater harvesting areas, the weighted linear combination (WLC) was applied in the range of 0 to 1 using the multi-criteri evaluation (MCE) within the ArcGIS and and the data of various criteria including distance to water source, distance to cattle post, stocking density, normalized difference vegetation index (NDVI), distance to road, slope percentage, distance to settlement and soil texture. The result indicated that about 2950 ha (~5.2%) of the study area have a good suitability for implementation of rainwater harvesting systems to supply water for grazing livestocks. The results of questionnaire survey revealed that about 70% of 107 stakeholders of the rangelands are highly willing to install and utilize rainwater harvesting systems, but high cost of installing is considered the main hinderance.

Sediment and erosion are two natural phenomena in watersheds. Due to irregular recording and sampling difficulties, daily data are not available for sediment records. Therefore, decision makers and researchers have to apply interpolating methods to estimated sediment yields. In this study, 30 watershed characteristics including physiography, geomorphology, vegetation, climate conditions in 69 watersheds located in the Karoon and Karkheh basins were used to statistical analysis. Based on the principle component analysis, eight characteristics including area, perimeter, river length, relief, mean of elevation at 85% upstream and 15% point of longest flow path and the number of landslide events were selected. Then using Cluster Analysis, six homogenous regions were identified and multiple regression models were applied. Due to constriction of large dames on the studied watersheds, access to the reliable data is a challenges for sediment yield analysis. Based on the sediment-precipitation double-mass curves 29 out of 35 stations were influenced by upstream dam. Results indicated that the effects of large reservoir dams can influence the downstream sediment yield along 98 Km of river length. The results show that in each group a particular combination of variables influence the sediment yields of the watersheds. According to the validation indices (NS and R2) the obtained models have the high performance (R2 = 0.71 and NS=0.72). In general, the physiographic characteristics of the watershed such as length, area, main flow path and relief are more important than other climatic, vegetation and geological factors. The total explain variance by the mentioned variables is 87.3%.

In this study, land use change trend in coastal areas of south of Iran, including Sistan Baluchestan, Hormozgan, Bushehr were studied during 31 years (1988-2019). Landsat satellite images including TM, ETM +, OLI were used for this purpose. The maximum likelihood method was also used to classify satellite images. Vegetation indices (SAVI) and salinity index (SI1) were used to influence land use classes on land degradation and desertification. The results of land use change trend showed that Changes in land use classes of man-made areas and saline lands as the most dynamic land use classes followed an increasing trend of 2.72% and 1.14%, respectively. The results of multivariate regression analysis showed that three vegetation, saline and man-made variables, and four vegetation, saline, man-made and sandy areas explain 22.3% and 37.8% of the dependent variables of vegetation and salinity indices, respectively. Therefore, in more than 60% of changes, other environmental variables are affected. Hence, with respect to the results of land use area and regression analysis and the mean trend of SAVI and SI1 changes, where vegetation and SAVI classes show decreasing trend and saline land and SI1 classes have increasing trend, it can be concluded that land use changes is phenomena that changes ecosystem services with almost irreversible impacts. This will have nothing to do with disturbing the ecosystem balance and intensifying land degradation in coastal areas.

In Iran, due to arid and semi-arid weather conditions the optimal use of limited water and soil resources has a particular importance. Land degradation is the result of incorrect policies in land management, which is a prominent example in the Bakhtegan watershed. Human factors, as well as climate changes and the phenomenon of drought in recent years, have caused the area to be severely degraded in terms of water and soil resources and the life of Bakhtegan wetland has been subject to destruction. In this study, it was tried to identify natural and ecological factors as well as human parameters affecting the destruction and vulnerability of the area using fuzzy classification method and hierarchical analysis method (AHP) as well as the capabilities of GIS modeling, the data from the criteria and effective layers have been used and the level of vulnerability and land degradation has been determined. According to the results of the research, the level of land degradation and instability in the area has a large extent (48% of the area), However, the level of vulnerability in the central and downstream regions of the watershed and often in areas affected by human factors such as high population density, consumption of water in the agricultural sector, improper management of land use in the region, as well as dams and dike construction, has been increased. It was also concluded that human parameters have a more significant role in the degradation and vulnerability of the region compared to ecological and environmental factors.

Over the past few decades due to population growth and urban development, urban runoff has increased and led to different problems such as inundation of urban pathways, dissemination of environmental pollutions and flood hazards. In order to urban runoff management, it is necessary to estimate runoff rate correctly. SWMM is one of the most widely used models in estimating urban runoff. The goal of this research is to evaluate the performance of SWMM model in simulating flow rate in an urban watershed in District 22 of Tehran. At first, model required parameters were calculated. For model evaluation and validation, in three events, runoff was measured in the watershed outlet and was compared with simulated runoff. The model validation results showed that the simulated flow rates had good adaptation with the observed ones. The validation results were used for estimating optimum values of model input parameters. The results of SWMM model evaluation confirm model accuracy with NS= 0.72 and RSR= 0.53 and indicate the model ability in simulating urban runoff. So, SWMM model can be used for urban runoff management plans and designing urban runoff drainage networks in this area.

The aim of this study was conducted to investigate the effect of 25 years old exclosure on the function of aerial and underground organs of Trifolium pratense since may to july of 2017. Three sites inside and three outside of the exclosure were selected in the rangelands in Shoghaldare- Namin rangelands, Ardabil. Three transects with the length of 100 meters were established in each site and from 10 plots of 1 m2 vegetation characteristics including total production, canopy percentage and forbs canopy were estimated. In order to select T. pratense stand and measure the selected parameters (to study the effect of exclosure on the function of different organs of T. pratense), in addition to previous transects, in each site was randomly established 3 transect of 50 meters. Along each transect, 10 random points and in each point the nearest plant was selected. Length of root, stem, inflorescence, plant height and basal diameter of T. pratense were recorded. Moreover, the inflorescences, stems and roots of the selected T. pratense were cut and after air-drying, they were weighed with a precision scale. Results showed that the total production in the exclosure (2413/06 kg/ha) has significant difference (p < 0/01) with the outside of exclosure (963/84 kg/ha). The production of T. pratense inside exclosure (99.83 kg/ha) has also significant difference (p < 0/01) with outside the exclosure (22.75 kg/ha). Interaction of exclosure and elevation has significant effect on canopy cover (forbs and total), number of inflorescences, basal diameter, weight of plant organs (p < 0/01) and recovery effort (p < 0/05).

The symbiosis of arbuscular mycorrhizal fungi with plants root plays an important role in the sustainability and development of medicinal plant communities in ecosystems which are subject to various physical and ecological pressures.Teucrium polium L. is one of the most important medicinal plants that exists in these areas. In this study after identifying three species of mycorrhizal fungi consist of G. rosea، S. constrictum، G. intraradices which were abundant in the soil of the root zone, The spores were propagated separately and a combination of fungi. Then spores were inoculated with T. polium seeds in a completely randomized design with three replications under greenhouse conditions. After the end of growth period, results showed that the highest stem length was related to G. intraradices. The highest fresh and dry weight of shoots (1.61 and 4.34 g) and root dry weight (0.7 g) were related to combined fungi treatment that showed a significant difference with other treatments. Also the combination of fungi had the highest carotenoid concentration (7.32%). Inoculation of plants with fungal treatments of G. rosea, S. constrictum and G. intraradices (separately) also significantly increased chlorophyll (a) concentration compared to control. Eventually, the results showed the beneficial effects of mycorrhizal symbiosis in T. polium plant that combined use of these fungi can have a much greater and better effect on improving plant growth conditions, as fungi exist in form of combination in nature.

This study was carried out around Zooir oil well in Khouzestan to investigate the concentration of heavy metals (Pb, Cu, Zn, Cd) in soil and two species of plants (Alhagi camelorum and Cornulaca monacantha), two directions of dominant wind and opposite direction of dominant wind and three distances from oil well. The results showed that the concentration of lead, copper and zinc of soil in the wind direction was significantly higher than the opposite wind direction, whereas in the concentration of these elements in the plant, there was no significant effect. This is exactly opposite in the case of cadmium metal. The concentrations of the studied metals in both soil and plants collected from different distances were significantly different at 1% level. The two lead and zinc metals have significant differences in the surface and deep soils, but these were no significant for the cadmium and copper metals as well as in the soils under and between the plants. Heavy metal uptake was no significant effect in the two studied species, but this difference was significant between the shoots and roots. Cadmium and copper have the highest concentration in roots. Lead and zinc have the highest concentration in aerial parts. Evaluation of accumulation and transport factors showed that lead, zinc and cadmium in Cornulaca mocnaantha and lead and zinc in Alhagi camelorum had TF> 1 coefficients, so they could be used to refine soils polluted with these elements. BAC and BCF values for both species were less than one.