نشریه تحقیقات منابع طبیعی تجدید شونده
سال هفتم شماره 4 (پیاپی 26، زمستان 1395)

Canopy gaps have an important role in establishing of natural regeneration and determining the vegetation composition in forest ecosystems. The regeneration of oak trees can lead to better management of forest stands. This study was performed in the Oak forest of northern Khorasan to investigate the characteristics of established seedlings in forest gaps. To study the natural regeneration in the forests, 30 gaps in the protected area and 30 gaps in the unprotected area were selected (in three classes). At first, the gaps area was recorded and the selected parameters such as slope, direction, height, herb layer were measured. The specifications of quantitative parameters (light intensity, regeneration, diameter at breast height (1.30 m) and collar diameter of oak seedling (Quercus castaneifolia) and qualitative (mode of branching, crown shape) in various gaps were studied. There was a significant difference between these two regions in terms of the parameters mentioned except collar diameter and diameter at breast height of the seedlings. The regenerations in both areas in the gaps of 500-800 m2 have had a better situation than other gaps. In addition, the best condition was qualitatively observed in the gaps of500-800 m2. Finally, it can be concluded that the regeneration in the protected area both quantitative and qualitative was in a more suitable situation than the unprotected area, because the unprotected area was closer to the village and under more destruction and utilization than the dense area.

One of the newest methods to determine the amount and type of many environmental pollutants is the use of natural bio-detector method. In the temperate regions a layer of wood (growth ring) is yearly added to the tree, in which the growth ring, habitat conditions recorded in the same year are a good option for bio- detector over time. In this research, the poplar trees which are abundantly cultivated around the Zanjan's lead and zinc factory were used as a bio-detector to illustrate the process of surrounding soil pollution. For this purpose, 2 trees were selected and cut from 5 and 10 km intervals of Zanjan's lead and zinc factory as well as was sampled from the surrounding soil of each tree. The age of the trees was determined through the annual rings (growth rings). The concentration of lead and zinc was determined in each of the annual ring and also soil samples. The results demonstrated that the amount pollution of soil and wood samples near to the mentioned factory was higher than other samples. The amount of lead and zinc in the annual growth rings of poplar tree showed an increasing trend from 1991 to 2010, but this increase was significantly observed in the trees close to the factory. The statistical analysis demonstrated a significant correlation between the amount of lead and zinc with the aforementioned years (p˂0.01). The amount of lead and zinc in the studied soils and trees were also increased per year. Furthermore, the statistical analysis (correlation analysis) indicated that there is no significant pollutants movement between the annual rings. Therefore, it can be concluded that poplar trees can be used as a bio-detector for the polluted soils to lead and zinc metals in the study area.

In this research, the dependent and interaction effects of three organic pesticides (Propiconazole, Tebuconazole, and Chlorothalonile) and water-methanol extract of inner bark (endoderm) of barberry stem with different concentrations (50, 150, 250, 350, and 450 ppm) was investigated on the white-root fungus of Rainbow (Trametes versicolor). The tests were done in the in vitro and using malt-extract agar culture and agar-disk diffusion method (modified method of CLSI standard (2008)). The plates were placed inside the incubator at 23 °C and 75% relative humidity for one week. In addition, the growth of mycelium fungus and inhibition effects of different preservative solutions against fungus was also measured daily for one week. The results demonstrated that inner bark extract of barberry stem and chlorothalonil pesticide did not alone have any inhibition effect on the growth of fungus, while the propiconazole and tebuconazole pesticides alone had a significant effect on the growth of fungus in various concentrations. In the study of the combined effects of preservative solutions showed that tebuconazole at the 450 ppm concentration and propiconazole at all of mentioned concentrations along with inner bark extract of barberry stem could prevent to the extent acceptable from the fungus growth. It can conclude that the propiconazole and tebuconazole pesticides along with the extract of the inner bark of barberry create a synergistic effect in preventing the growth of tested fungus.

The forage and Astragalus productions are main products and major sub-products of semi-arid regions of Isfahan rangelands. Some economic indices of harvesting and selling of Astragalus sub-products were evaluated. Therefore, the statistical papulation in the study included beneficiaries operators of the forage and Astragalus product. In addition, data were obtained through field work using unstructured interviews as well as direct observation. Results showed that marketing margin for Astragalus gossypinus and Astragalus verus were 44.44 and 42.5 percent, respectively. Besides, annual net income obtained by harvesting of forage species was 106 million Rials. That was nearly 76% of annual income of each rural household. And also, the annual net income obtained by harvesting both species of Astragalus gossypinus and Astragalus verus were 11.78 million Rials, that was 8.47% of each household income. Royalties for forage and Astragalus product were also estimated 2.65 billion Rials per hectares annually and 5.46 billion Rials per year, respectively. Furthermore, the findings indicated that the share of annual employment for forage production and Astragalus utilization were estimated 120 and 68 people, respectively. The share of Astragalus by-product of total employment obtained from forage and by product was also estimated at about 64.39 percent. The results demonstrated that the use of Astragalus has been a profitable economic activity, which along with other rangeland products such as forage play an important role in the local economy and the area. In addition to creating jobs, it reduces the degradation and conversion of pastures to drylands. In addition, the economic investigation, particularly assessment and evaluation of market and non- market functions of rangelands can assist to better introduce the true value andfunctions of this resource as well as designing appropriate mechanisms for conservation and optimal utilization in all levels of management.

Understanding the relationships between vegetation and environmental factors would be essential for rangeland restoration and management. So the current study determines the relationship between indicator plant species and soil in the summer rangelands of Balade, Nour. After determining the vegetation types using topography, the sampling was done with systematic-random method. The plots size was determined using the minimum area method. Soil samples were collected in each vegetation type from 0 – 50 cm depth (effective root depth). In addition, Samples to determine some of the factors such as the percentage of sand, silt, clay, pH, Ec, T.N.V, CO, saturation moisture content and sodium absorption ratio were transferred to laboratory. In this research, relationship between the soil's characteristics and vegetation's parameters were analyzed after data providing about soil and plant by ordination method which is a method to determine the relationship between plant communities and environmental factors. Therefore, to determine the type of ordination method, firstly, the gradient Length was measured by DCCA method. Finally, the gradient length data were analyzed by CANOCO software. The results showed that the types of Astragalus gossypinus and Acontholimon pterostegium have had negative and positive correlation with saturation moisture content and sand, respectively. Furthermore, herbaceous species of Bromus tomentellus and Coronilla varia had positive correlation with saturation moisture content and organic carbon. Therefore, such results could be useful to improve and restore vegetation in areas with similar conditions.

Probiotics are feed supplements which have beneficial effects on the hosts and promote intestine microbial flora and growth parameters. In this study, 240 specimens common carp (Cyprinus carpio) with mean weight of 12±0.5 g in 4 treatments were fed in triplicate by different levels of Lactobacillus acidophilus probiotic (control group without probiotic, treatment 1 with 5 percent of feed weight, treatment 2 with 7% of feed weight, and treatment 3 with 9% of feed weight) in same condition for 60 days and Its their effects on growth parameters and survival were evaluated. Results showed that 7 percent Lactobacillus acidophilus had a significant difference with the control group and led to an increase in specific growth rate and final body weight in common carp fry (P<0/05). At the end of experiment 7 percent Lactobacillus acidophilusin feed led to an increase in survival rate. According to the results, adding Lactobacillus acidophilusin in the diet is suggested for better and survival in common carp diet.