نشریه پژوهش های آبخیزداری
پیاپی 110 (بهار 1395)

The aim of this study was to determine diversity of plant species in Hackberry sites in Taniyan and Rezvanshahr areas in Guilan province. For this aim, circular sampling plots of 0.1 ha were implemented selectively based on presence of the Hackberry trees in study area. In sampling plots, DBH of all trees and number of all shrubs were measured. For wood species regeneration, a sampling plot of 100 m2 was implemented in center of large sampling plots and regeneration counted. Also, for record of herbaceous species, Whittaker nested plot method used that 32 m2 obtained. Values of diversity, evenness and richness were calculated using biodiversity indicators in trees, shrub, regeneration and herbaceous layers. The results showed that Menhinic richness index in tree (1.47) and regeneration (0.91) layers in Rezvanshahr site has more than Taniyan site. Maximum of Shannon-wiener index value in both site was in the tree (2.05) layer and lowest was in shrub (0.27) layer in Rezvanshahr site and in regeneration (1.05) layer in Taniyan site. Shannon-wiener diversity index in tree (2.05) and regeneration (1.56) layers in Rezvanshahr site was more than Taniyan site. Amount of this index in shrub (1.36) and herbaceous (1.2) layers in Taniyan site was more than Rezvanshahr site. Also, Smith and Wilson evenness index in each four layers of tree (0.45), shrub (0.58), regeneration (0.63) and herbaceous (0.54) in the Taniyan site more than Rezvanshahr site. Also, in study areas, species abundance followed in tree layer of the broken stick model and in herbaceous layer of log normal model in Rezvanshahr site and followed of broken stick model in Taniyan site.

Proper utilizing based on scientific principles is one of the requirements of stable range management one of the requirements for proper range management is Knowledge of grazing behavior of livestock. For this purpose, in this study, the grazing behavior of sheep in the steppe rangeland of Dehno was investigated. Initially a three-year-old Ewe was selected, then using a geographic positioning system (GPS), the path of movement, the time of arrival and departure to the rangeland and its movement speed, duration and time of its resting was recorded. Then the data were statistically analyzed using two-way analysis of variance. The results showed that, except for the walked distance by livestock during the years and months and the spent time for movement, there is no significant difference between the measured parameters of grazing behavior during the three years of study. The most walked distance referred to 2010 and the most spent time for movement referred to March, while the lowest time was for June. The most walked distance from the sheep has occurred in slope gradient ranging from 0 to 8% that covered with Artemisia sieberi - Zygophyllum eurypterum. According to the results, the climate and vegetation condition had been effect on livestock grazing behavior. Thus the study of animal grazing behavior in different climate conditions play an important role in the regulation of grazing program and optimal use of the forage capacity of rangeland ecosystems.

Bunium persicum belongs to Apiaceae family and is an important medicinal plant. This biennial plant has vegetation growth in its first year and reproductive growth in the second year. The species is not cultivated due to dormancy difficulties and also overuse of natural habitat which has increased the risks of its extinction. This study was carried out to find the best methods of breaking seed dormancy and germination stimulation. Four treatments were used including a) Stratification for 0, 1, 2, 3 and 4 weeks, b) Gibberellic acid (GA3) with concentrations of 100,500 and 1000 ppm, c) Sulfuric acid for 1.5, 2.5 and 5 minutes, d) Salicylic acid (SA) with concentrations of 1, 1.5 and 5mM . The Results showed that stratification treatment after 23 days and Gibberellic acid by the concentration of 500 ppm were the most effective treatments in increasing seed germination. All three concentrations of Salicylic acid reduced germination, and using Sulfuric acid for 1.5 minutes had no significant effect on germination, while other 2 levels led to germination reduction.

Nowadays, soil and water conservation is one of important methods for the natural resources management. There are several ways to do this. One of these methods is the use of organic mulches. In this research, the effect of Agropyron elongatum residueon runoff and soil loss were examined in three cover percentages (0, 30 and 70%) with diameters 4 cm in length and 0.35 cm width in the laboratory conditions using rainfall simulator. The experiments were carried out in a plot with 2 meters length, 1 meter width and 0.2 meter depth, where 0.2 m of the depth of plots was filled with silty loam soil. Then plants residue was covered soil surface and simulated rainfall intensity was 50 mm per hour for 20 minutes. After experimental rainfall simulations, the amount of runoff and sediment were measured. LSD test results in cover percentages of (0, 30 and 70%) for 4cm size showed there are significant differences in runoff volume, sediment load, sediment concentration and runoff coefficient at 95% level of confidence (sig ≤0.05) between the percent cover (0, 30 and 70%) of this size.

Soil saturated hydraulic conductivity (Ks) is among the most important soil hydraulic-physical properties that required for soil-water modeling. Due to high cost and time- consuming nature of Ks measurement, estimating Ks from basic, inexpensive and easily measured physical and chemical soil properties is becoming increasingly important. In the last two decades, the development of estimation methods called pedotransfer functions that use cheap auxiliary variables has been a sharpening focus of soil research. This study was conducted (i) to develop different pedotransfer functions and (ii) to evaluate and compare statistical regression and neural network based pedotransfer functions for estimating Ks in a sub- catchment of Zayanderood River, located in Chaharmahal-va-Backtiari province. The data set was divided in to subsets for modeling (n=86) and validation (n=25). Root-mean-square error (RMSE), mean error (ME) and percentage of relative improvement (RI) were used as the validation indices. The artificial neural network-based models provided more reliable estimation than the statistical regression-based pedotransfer functions.

most conventional methods use chemical polymers and petroleum products (particularly, in arid and semiarid zones) to stop dust storm which are considerably labor, cost and time consuming. Use of the chemical polymers have several drawbacks such as high price of chemicals and their potentially harmfulness to environment. Using bio polymers has received worldwide attention during the last two decades owing to their great potential as a soil additives to stabilize the soil. The results obtained from different types of biopolymers or biopolymer compositions implicitly represent them to be applicable for binding the soil particles at the surface of light soils. Application of biopolymer as a stabilizer has proved to be effective for prevention of dust storms by stabilizing soil structure. The objective of this study was to use and screen a series of biopolymers to quantify their effectiveness as dust stabilizer in the laboratory scale. In this study, 20 biopolymer stabilizers be used. In order to assess the influence of biopolymers upon topsoil stabilization, laboratory tests on unconfined compressive strength, wet aggrigate stability and erosion resistance of untreated and treated soil samples be performed. In laboratory the wind speed in the tunnel be gradually increased from 0 to 25.6 m/s during 15 minutes . The wind erosion, compressive strength and aggregate stability test results clearly indicated that S3, S4, S5, S6, S7, S8, S9, S10, S12, S14 specimens were useful to dust control, in the relatively arid and semiarid areas. The SEM image showed that when biopolymers were applied to soil, a part of them filled up the voids of soil, and other part stayed on the soil aggregates surface. The polyelectrolyte groups in its molecular structure had chemical reaction with positive ions of clay grain and create physicochemical bonds between molecules and soil aggregates with ionic, hydrogen, or Van der Waals bonds. Untreated sample hadn’t bonds between molecules and soil aggregate so, the compressive strength and aggregate stability were very weak in these samples.

The present study was conducted to classify vegetation and determining relationship between plant species distributions and environmental factors in rangelands of Qom Province. Sampling of vegetation was done by Random systematic method. The distance between each transect was 500 meters and the distance between plots per transect also varied depending on the length of transect. With regard to the type of the species the plot size determined by the minimal area method Between 2 and 25 m2 and sample size were determined 60 plots by considering to the changes in vegetation. In addition to recording of vegetation features in plots (Plant species name and canopy cover) related information on habitat such as slope, aspect and elevation were also recorded. At each habitat, soil Sampling was performed by drilling of eight soil profiles and sampling from 0-30 and 30-80 cm depths. After sampling, soil characteristics consisting gravel percent, texture, saturation moisture, available water, lime, gypsum, organic matter, Acidity (pH), Electrical conductivity (EC) and soluble Solute (Na, Ca2, Mg2, K, Cl-, Co32-, Hco3- and So42-) were measured by routine methods. The vegetation classification was done using TWINSPAN method. By performing classification, seven plant groups consisting nine habitats were diagnosed. To analyze the relationship between vegetation and environmental factors, PCA and CCA Analysis were performed. Based on the results, in downstream soil saturation moisture, conductivity, acidity, texture and Lime and in the upstream of the study area gravel, altitude, and slope are factors which have greatest impact on the distribution of plant species habitats in the study area. Understanding of requirment ecological of plant species and environmental characteristics of each region will bring choice of species which are more compatible to the conditions of each region, and as a result the success of vegetation the rehabiltation activities.

This study is conducted to identify relationship between the amount of forage production with topographic (elevation, slope and aspect) and climatic (rainfall and minimum, maximum and mean temperature parameters) variables in Sabalan’s rangelands. Using digital elevation model, rainfall, slope and aspect classes maps was prepared environment. In preparing rainfall and temperature parameters classes maps, data of weather stations and derived relavant gradient were used. Then, by considering vegetation types and different elevations, slopes, aspects, rainfall, and temprature parameter classes in the maximum vegetative growing stage, annual production using one square meter plots by cutting and weighting method was harvested. Topographic and climatic variables for plots was derived using prepared maps. To determine the most important affective environmental factor or factors in production vaiation, principal component analysis method used. Results show that from the selected environmental factors based on the firest two components, elevation, rainfall, mean temperature and slope have the most effect on the production of Sabalan’s, which the first component 68.13% and the second component 14.96% of changes and the two components totally 83.09% were covered of the changes. Moreover, results of correlation analysis show that the mean of temperature has negative effect and other factors have positive effect on the changes of production. Therefore, in the assessment of production and grazing capacity such as Sabalan rangeland, topographic and climatic factors should be considered.

In order to determination of suitable cropping pattern for agricultural lands of Golestan province, were used geographical information system (GIS) and analytical hierarchy process (AHP).
At first, agroecological requirements of crops were identified from scientific resources then classified and required thematic maps were provided. The digital environmental layers overlaid and integrated in GIS media with AHP weights, then zoning of lands were done in 4 classes for any crops. In future step, the crops feasibility maps and land type and unit maps (as management unit) were overlaid then were identified the high suitable and suitable classes in each unit for crops cultivation and suitable cropping pattern was selected with respect to parameters such as plant water requirements, water resources status, the net benefit and the other economic and development factors. In introduced patterns for south lands of province, were suggested dry farming of high net benefits and autumn crops. In the most agricultural lands in southern and central of province were proposed crops such as wheat, canola, beans, chickpea, berseem clover in the patterns. The results showed that the north and northeastern lands of this province, has more adapted to cropping pattern of chickpea and barley due to environmental constraints. Also, cultivation of spring and summer crops is possible in high suitable areas, in the south and southwestern province as rainfed farming with supplementary irrigation.

Application of chemical polymers is one the effective methods for stabilization of soils. In this research, the effects of Polyvinyl Acetate Polymer on stabilization of soils and erosion control has been investigated. To do this, three different soils types were treated with five levels of Polyvinyl-Acetate emulsion and cured for three ages. Thus, considering three replication for each samples totally 135 specimens were prepared and tested for determination of their compressive strength. Statistical analysis of the results showed that the adding of polymer increases the compressive strength of the samples significantly, where the rate of increase depends on soil texture and varies from 15 % in clayey samples to 400 % in sandy soils. Furthermore, the compressive strength of the samples significantly affected by the age of the samples and deacreased upto 15 and 28 percet after 3 and 6 months respectively. Also based on durability tests, addition of polymer to the samples makes the sandy samples durable but has no effect on the durability of clay samples. Finally, application 25 g of polymer per square meter of soil was determined as the optimal treatment to stabilize the studied soil.