نشریه تحقیقات منابع طبیعی تجدید شونده
سال ششم شماره 1 (پیاپی 19، بهار 1394)

This study examined the effect of mulch to keep soil moisture of Haloxylon plants of Semnan province in a randomized complete block design with 2 main plots and sub-plots plastic mulch natural and artificial white, black, coarse and fine sand each with 3 replications in different areas. The seedlings of Haloxylon aphyllum separated by a distance of 3 km from the plots and planted in the pan to a thickness of 5 cm of mulch. Area without mulch was used as a control treatment. Watering operation was carried out in this regard that only the monthly irrigation control and other treatments didn’t irrigate during the experimental period. TDR sensors installed in each treatment and soil moisture, plant height, followed by the coefficient k were measured every other 10-day. The results showed that the effect of mulch on soil moisture factor was significantly (p>0.05). Black plastic, sand and coarse treatment had the lowest soil moisture, while the coarse sand control treatment had no significant difference (p<0.05). The highest coefficient k was obtained in the treatment of black plastic and the lowest found in the treatment of soft sand. In general, treatment of black plastic (synthetic mulch) showed significant difference between coarse and fine sand with natural treatments (p<0.05) and the coefficient k mulch treatments had no significant difference from the control group (p>0.05). Significant differences in term of soil moisture and k factor was found between the groups. The findings showed that natural mulch in all variables had less average soil moisture than synthetic mulch and, therefore, was more favorable.

This study was done in order to determine the pollution effects on growth of macrobenthoses in Jadjrud River, between Saeedabad area and Ghareboron village. Three stations considered for invertebrates sampling. Assessment of some parameters such as air and water temperature, BOD5, dissolved oxygen, and pH were done monthly along with invertebrate sampling. Total existence, EPT existence, Shanon-Winner diversity index and HFB1 were used in assessment of macrobenthoses. During experiment, air and water temperature were 1.3-32.5 and 3-25.1 °C, respectively. BOD5 was 3.9-9.98 mg L-1, dissolved oxygen 4.85-9.52 mg L-1, and pH 8.8-9.6. In benthic fauna assessment, 7 orders and 5 genera were known, where some resistant groups against pollution such as Diptera, families of chironomidae and gastropods were dominant in estuary zone of the river. Maximum and minimum EPT dominance were 45% in spring (station 3), and 34% in summer (station 2), respectively. The results of this study showed that the pollution in station 1 was considerable, station 2 highly polluted, and station 3 relatively polluted. Based on Helsinhophe index, water quality in first station was low, while in station 2 was highly low an in station 3 was relatively low.

This study conducted to investigate usability of soya stalk as lignocellulosic material and wood alternative in particleboard manufacturing. Four levels of soya stalk (25, 50, 75, and 100%), 3 level of press time (5, 6, and 7 min), and the content of resin in 3 levels (8, 10, and 12%) were considered as dependent variables. Results showed that bending properties (MOR and MOE) were enhanced by increasing soya stalk content in boards, while internal bonding (IB) property decreased. However, water uptake and thickness swelling after 2 and 24 immersions were increased. With increasing in resin content and press time, both mechanical and physical properties including bonding properties, internal bonding properties, water uptake and thickness swelling were suppressed. The results showed that soya stalk is a suitable wood alternative in particleboard manufacturing.

A 14-days period experiment of larval first feeding was conducted to investigate the effects of Daphnia magna enriched with cod liver and canola oils on growth and survival of the Caspian kutum larvae. The feeding trial of the Kutum (Rutilus kutum) larvae with initial weight of 52.6±2.11 mg at density of 10 No L-1 based on completely randomized design with three replications for each treatment as follows: 1) non-enriched Daphnia, 2) enriched Daphnia with cod liver oil and 3), and enriched Daphnia with canola oil. Results showed that body weight and specific growth rate of larvae fed with enriched Daphnia were significantly higher than larvae fed with non-enriched Daphnia (p<0.05). However, no significant difference was observed in the survival rate between the treatments (p>0.05). Maximum and minimum levels of SGR were observed in the larvae fed with Daphnia magna enriched with canola oil (8.50±0.01) and non-enriched Daphnia (7.50±1.12), respectively. The present study indicates that canola oil can be replaced with fish oil for enrichment of Daphnia for feeding the Caspian kutum larvae.

In this research, feasibility of palm lignocellulosic particles application was investigated in the manufacture of wood-cement composite panels. The variable factors of this investigation were including palm lignocellulosic particles content in three levels 10, 15, and 20 % and calcium chloride in three levels including 0, 3, and 6%. The other factors consist of pressing compression, pressing time in 12 hour, dry weight, and panel dimensions (40×40×1.5 cm) were kept constant. The specimens were prepared from manufactured panels according to DIN 68763 standard and their mechanical properties such as flexural strength, modulus of elasticity, and internal bonding (IB) were measured. The results indicated that the increase of lignocellulosic particles content have been caused weak of mechanical strength of manufactured panels and the increase of calcium chloride until 6% level have been caused a gain of strengths. In this investigation, the panels manufactured with 10% content of lignocellulosic particles and 6% content of calcium chloride had the best flexural strength, modulus of elasticity, and internal bonding.

The main goal of this study was to estimate the geographic distribution of Artemisia sieberi and Artemisia aucheri by models based on occurrence data. Because of widespread use, two methods including Maximum Entropy modeling technique (MaxEnt) and Ecological-niche Factor Analysis (ENFA) selected. For this purpose, a research was conducted in north east rangelands of Semnan. Modeling vegetation data in addition to site condition in formation including topography, climate, geology and soil was prepared. Sampling was done within each unit of sampling parallel transects and 1 vertical transect with 300 m length, each containing 15 quadrates (according to vegetation variations) were established. Quadrate size was determined for each vegetation type using the minimal area method. Soil samples were taken from 0-20 cm and 20-80 cm in starting and ending points of each transect. Soil properties included gravel, texture, organic matter, lime, pH and electrical conductivity were measured. Maps of environmental variables were created by Geographic Information System (GIS) and geostatistics. Then predictive distribution maps of both species were produced using the MaxEnt and ENFA models. Model accuracy in MaxEnt method is evaluated by using the area under the Curve (AUC). By jackknife method and response curve, the most important environmental predictor variables were found. By importing the information layers in appropriate model and using necessary statistical analysis in biomapper software, the map of potential habitat has been created. To evaluate the accuracy of the model, Boyce index has been used and model rectitude in this test was determined as 83.4 percent for A. aucheri but A. sieberi wasn’t achieved sufficient accuracy. In this study, the adequacy of vegetation type mapping was evaluated using kappa statistics and potential habitat map of A. aucheri by MaxEnt method was higher kappa (0.85). Finally, lime 1, gravel 1, lime 2 and slope were significantly affected habitat distribution of A. aucheri, while habitat distribution of A. sieberi affected by elevation, silt 1, and lime 1. MaxEnt, ENFA, and other models based on sampling process to estimate probability of occurrence should be considered as important alternatives for some species distribution models in rangelands.

In this study, effects of flour content and nanoclay loading on the physical and mechanical properties of wood plastic composite were investigated. Flour of cellulosic shell of Pistachio in levels of 30, 40 and 50 and nano clay of cloisite 15A in three levels (0, 3 and 5%) was mixed with high density polyethylene (HDPE). Samples were made with a laboratory twin-screw extruder and then injection molding. The heating temperature profile and rotational speed of the screws were set to 60 rpm at 160, 170, and180 °C, respectively. Mechanical properties including tensile and flexural properties as well as notched impact strength and physical properties including water absorption and thickness swelling were measured. The results showed that flexural and tensile modulus and strength, notched impact resistance, water absorption and thickness swelling of the samples increased as the flour content increased from 30 to 50% (w/w). Furthermore, flexural and tensile modulus and strength, water absorption and thickness swelling of the samples decreased as the Nannoclay content increased from 0 to 5% (w/w), but notched impact resistance increased.