نشریه پژوهش های آبخیزداری
پیاپی 106 (بهار 1394)

An experiment was carried out to evaluate the allelopathic potential of various concentrations of (0, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100%) of Atriplex canescens and Atriplex lentiformis which were prepared by aqueous suspension of 10% at the flowering stage on some germination traits (Root length, shoot length, seedling growth, germination percent, speed of germination, vigor index), physiological (total chlorophyll content) and biochemical (total phenols content) shoot let and leaflet of Agropyron elongatum as a non native plant which is introduced on range management projects of the eastern Golestan province in laboratory of Hydro-ecology at Gonbad-e-Kavous University. The experiment was conducted in a completely randomized design with three replications. The ANOVA analysis showed that species, various concentrations and the interaction of species and concentrations had significant difference at 1% on radicle length, speed of germination, seedling vigor index, total chlorophyll and total phenol content from shoot let and leaflet of A. elongatum. The interaction of species and concentrations on germination percent was significant at 5%. While the effect of them on shoot and seedling lengths were insignificant. The mean comparison of interactions effect of species and various concentrations indicated that there were significant decrease on total chlorophyll content and, radicle length, germination percent, speed of germination and seedling vigor index with increasing concentrations of two species of Atriplex as compared to control. On the other hand, the amount of total phenols of seedling had a rising trend with increasing concentrations trend over control. 100% of concentrations aqueous extract of A. canesence had a maximum of Phenols content (194/38%) as compared to control.

Low doses of gamma radiation are widely used to stimulate seed germination, growth and crop production. This study was conducted to study effect of irradiation with doses of 20, 30, 50, 100 and 150 Gy of gamma ray on seeds of two species of Ag. elongatum and Br. tomentellus. For this purpose, for each species in an experiment with completely randomized design, three replications of treated seeds with gamma ray were sown in plastic pots and the parameters of germination capacity, germination rate, germination value and biomass of shoots and roots was evaluated. The results showed the treat of 30 gray had the most significant effects on the evaluated parameters of Ag. elongatum, and the most increase in germination rate, germination value (P

Due to the involvement of the human and natural phenomenon ecosystem management is basically difficult and complex matter, so management with systemic approach is necessary. This management must be comprehensive, cause resources sustainability and improve economic and social situation of watersheds stakeholders. Due to the complex and mutual interaction of watershed residents with natural resources, the social and economic status improvement of these communities can be effective factor in improving the status of natural resource. Hence, the present study tries to present the strategies to improve the economic and social status of Fars watershed residents using network analysis and Super Decision software. The Statistics community of this research was PhD students and professors of promoting and management desert areas department, Agricultural College, Shiraz University. Measuring instruments of research was direct interviews and questionnaires, finally 30 questionnaires were filled by experts. The results showed that “the government support in order to establish manufacturing unit, not only rural agriculture” is the first priority with the score of 0.281. After that the factor of “providing gas, electricity and roads to small rural areas” was the second priority with score of 0.249. Also, improving public health services has the least effect on socio-economic status of villagers between selected factors.

Today one of the important environmental issues is soil pollution with heavy metal. Pollutants entering to soil causes the gradual elimination of beneficial organisms from this habitat, therefore Biodiversity is the original condition for dynamics, self-regulation, balance and stability of soil ecosystems, is destroyed. Total metal concentrations in the environment do not necessarily reflect its degree of toxicity or bioavailability because the bioavailability greatly depends on various environmental conditions. On the other hand, Land use impacts on many physical and chemical properties of soils. Recognition effective processes on bioavailability of metals help in modeling and understanding the environmental effects of these elements in the soil. In order to investigate the influence of soil factors on the total form and mobility and bioavailability heavy metals in different land-use, 116 samples were taken from surface soil in three land use Including Needle leaf forest, broadleaf and Rangeland in Chitgar Forest Park located in the West of Tehran city. Mean annual precipitation based on 14 years statistics of Chitgar meteorological synoptic station from 1996 to 2010 were 267 mm and annual temperature was 17.2 degree centigrade. In the laboratory amount of calcium carbonate, pH, electrical conductivity, percent organic carbon, iron, copper, zinc and manganese in two form DTPA-extractable and total form was measured. Then, using stepwise regression methods most influential factors determined in each land use and were compared with each other. According to Mean comparison, the maximum amount of carbon was in the broad-leaves forests with average 2.7 that showed significant difference with Needle leaves forest with average 1.6 and pasture with average 0.8. Soil organic Carbon had a strong positive correlation with DTPA extractable Zn(R= 0.762). This correlation was variable between the land use types. Also, the amount of carbon showed a significant positive correlation with Fe and Mn DTPA form. One way variance analysis of calcium carbonate (CaCO3) had significant difference in all studied land uses (P

Pan evaporation is a key element in water resource planning, irrigation management and crop production. In most of the weather stations of country long term, homogen pan evaporation (Epan) data are not available. Hence, empirical model are used to estimate this variable.
The objective of this study was to compare the skill of regression and artificial neural network models in estimation of pan evaporation and determination of most affecting weather variables on Epan by principle factors analysis (PCA) approach using historical climatic datasets of four station namely Karaj, Ahvaz, Shiraz and Tabriz during period of 1986 to 2005.Meterological data including Maximum and Minimum temperature, wind speed and sunshine hours were used as predictors. Results of PCA approach revealed that in Ahvaz, Tabriz and Shiraz stations respectively 90%, 91% and 93% of pan evaporation variations can be attributed to wind speed, sunshine hours and Tmax, Tmin. PCA method did not perform well in Karaj. Application of ANN models showed acceptable results in all study stations. The R2 value was 0.81 in Ahwaz, Shiraz and Tabriz stations and 0.88 in Karaj station. Similarly, the RMSE values for Ahwaz, Shiraz and Tabriz stations was 0.2 mm and 0.1 mm for Karaj station. Besides, based on MSE2 index, the proposed model was overestimating in first three stations and underestimating in Karaj climate.MAE values in Karaj, Ahwaz, Shiraz and Tabriz were 3.83, 33.6,21.79 and 15.6 respectively. Results of multiple regressions showed that in Karaj, Tmax, in Tabriz station, wind velocity and in Shiraz station;Tmin are the most significant affecting variables on Epan with P values of 0.03,0.04 and 0.1 respectivelyý.

Soil seed bank is important for range management because it contains propagules of species that may be considered desirable or undesirable for site colonization after management and disturbance events. However, human-caused fire can affect ecological processes related to soil seed bank and vegetation structure. In order to determine the effects of burning on the seed bank, we germinated soil samples from burned and unburned plots in Haji-Ghoushan located in the Northern part of Gonbad city (Golestan Province) where human-caused fires in September 2010. In controlled laboratory conditions the total number of seedlings, number of families and subfamilies found in the upper (0-5 cm) and lower (5-10 cm) layers of soil within burn and no burn plots were recorded. Our research indicated that the total seedling density was higher in first depth than in second depth, and lower in burned site than unburned site; however, differences were non-significant but the number of seedlings varied significantly with depth. Twenty-four species were identified in unburned site. The species numbers in the seed bank of burned site were 18. The majority of the family was Poaceace, which was common to the two treatments. In unburned site, Poa Bulbosa and Stellaria media accounted for 17.76 % and 12.69 %, respectively of the seedling population. In the burned site we found Stellaria media and Pao Bulbosa accounted for 18.44 % and 15.63%, of the seedling population respectively. The densities of soil seed banks were highest at first depth in unburned and burned site with 337.5 and 282.5 m2. In the deeper depth, the density of soil seed banks was 96 and 70 m2 in unburned and burned sites, respectively. Species richness and diversity were obtained higher in unburned site than burned site and were higher in the upper depth than the lower depth in both sites.ý

Artificial neural network is a new method to estimate phenomena changes that have wide application in various branches of science. Reservoir sediment traps efficiency and sediment volume is an issue that can be investigated with this method. The purpose of this study is the determinate of sediment trapping efficiency in delayed dams and a comparison between neural network methods with regression models. So in this study, was used the physical model of delayed dams in the soil conservation and watershed management research center. In order to simulate a flood hydrograph, was used the idea of a linear reservoir model. Then with the release of flood and sediment trap sediments, examined the function of delayed dam. Then, with identify the affecting parameters on reservoirs sediment trapping; was developed neural network model on based back propagation of error. Also was applied the regression models for investigation the relationship between the parameters and compare the estimation results with observation. Finally, was applied the statistical indexes R2, RMSE and MAPE to assess the accuracy and precision of the model. According to results, the average values of R2, RMSE and MAPE in regression models are equal to 0.456, 26.6 and 62.1 respectively; but are the values in the neural network model 0.982, 4.6 and 6.1. So the artificial neural network has more ability in compared to regression equation to predict trap sediment in delayed dams. Also the results showed estimation of sediment trapping efficiency has depend on the number of parameters in equation and must be determined the optimized equation on based number of parameters.

This research was carried out to determine the value of forage production function using the pricing method of qualitative (Hedonic) in rangeland watershed basin of Taham. For this purpose, after estimating the annual production of forage in rangeland areas using cutting and weighting methods, the amount of allowable limit and the preference value of forges were estimated. In order to determine the amount of harvestable forage, the study tried to estimate the amount of allowable limit and the preference value of gorges using national plan data of harvestable forage in five sample regions of forages in Iran (2012) and the method presented by Arzani (2008). Finally the hedonic pricing method was used in order to estimate the price of forages produced. After determining the price of harvestable forages was calculated, the total amount of harvestable forages of the region was estimated to be 1452 tons per year. In this study, the average estimated TDN for the forage land was 0.47 percent per Kilogram. Meanwhile, the price of forages in the region was calculated to be 4120 Rials per Kilogram. On the basis of these findings, considering the determination of the price per Kilogram of usable forage and the determination of total amount of usable forage in the forage land of the region, the economic value of forage land was estimated to be 11958.9 million Rials per year and the economic value per hector of the forages of the region was determined to be 86.7 thousands Rials on an average.

In order to calculate the grazing capacity in range management plans is nessoceary to be aware about daily metabolizable energy requirement of livestock in rangelands at different climatic zone. In this regard, daily metabolizable energy requirement of Ghezel sheep in Sahand mountain rangelands were studied. According to the average values of forage quality indexs in plant species and their proportion in the composition of rangeland vegetation in different growth stages, metabolizable energy value in one kilogram of dry matter for livestock grazing rangelands was estimated and considering of daily metabolizable energy required of Ghezel sheep in Sahand mountain rangelands, amount of forage which supplies animal requirements in different stages of growth, were estimated. Daily requirement of ram, ewe and lambs of Ghezel sheep based on metabolizable energy, according to the MAFF equation (1984) proposed in the state of maintenance and livestock grazing in rangeland and considering the physical characteristics of the rangelands, intervals of animal drinking places, plants density and 60% additive coefficient, were calculated 14.25, 18.82 and 10.75 Mj respectively. According to the results, amount of forage required to provide the daily requirements ram, ewe and lambs of Ghezel sheep considering the forage quality of rangelands in 2008, in the initial stages of growth respectively is 1.61, 2.13 and 0.93; in the middle of stages growth respectively is 1.83, 2.42 and 1.06 and in the final stages of growth is 2.24, 2.96 and 1.30 Kilograms of dry forage. The amount of forage for 2009 in the initial stages of growth is 1.57, 2.08 and 0.91; in the middle of stages growth is 1.73, 2.28 and 1.00 and in the final stages of growth is 2.23, 2.94 and 1.29 Kilograms. Also, amount of forage required to provide the daily requirements ram, ewe and lambs of Ghezel sheep considering the forage quality of rangelands in 2010, in the initial stages of growth is 1.55, 2.04 and 0.90, respectively; in the middle of stages growth is 1.82, 2.40 and 1.06 and in the final stages of growth is 2.23, 2.94 and 1.29 Kilograms of dry forage, respectively. This implies that time grazing affects on the daily requirements of livestock and needed those daily requirements to be determined according to forage quality in of each stage. Obviously, depending on the conditions years it may some be changed quality of the forage plants but since the determination of forage quality is expensive, the results obtained can be used to estimate daily requirement use of livestock in the different years.

Determination of preference value of plant species which grazed by crossbred cows in the Tezkhrab rangelands by timing method desirability of forage plants for livestock and wild animals is an important factor in evaluating the appropriateness of pasture with livestock. This desirability in determination of range condition, range capacity of the pasture and scientific management of rangelands is used. Thus attention to the preference value of plant species in a region is a key factor which can guarantee the success of management in achieving its goals. Therefore the preference value of plant species by timing method for hybrid cow was determined. Method was this form That within 4 years and 6 months (May, June, July, August, September and October) and two times in one day each month and each time about 20 minutes from of grazing cattle was shot (Total 6 times) and then transfer film to Computer , Grazing time of plant species was determined. The results showed in 1% level There is significant differences Between different species in terms of duration and Percent of the time grazed. In addition, interaction between species - month on the time grazing and percent of time grazed was significant. Also results showed Percent of the time grazing no significant differences between species in different years, but time grazing and percent of time grazed in different months at 0.05 levels was significant.