نشریه تحقیقات منابع طبیعی تجدید شونده
سال نهم شماره 1 (پیاپی 29، بهار و تابستان 1397)

The aim of this study was to investigate the effects of nano-clay and press temperature on the physical and mechanical properties of parallel strand lumber made by the common reed straw. Three press temperatures of 160, 180, and 200 °С and nano-clay content of 0, 1.5% and 3% were separately considered. The melamine urea formaldehyde was used as adhesives substance. The press pressure (70 Kg cm-3 ) and time (20 min) were also considered as control variables. Physical tests including water absorption and thickness swelling in 2 and 24-hours’ time and mechanical tests including modulus of rupture and modulus of elasticity were also evaluated. Results showed that the water absorption and thickness swelling were decreased and increased by increasing the nano-clay up to 3% and the press temperature up to 200 °С , .respectivelyThe mechanical properties were increased and decreased by increasing the nano-clay up to 1.5% and more than 1.5%, respectively. The mechanical properties were improved by increasing the press temperature up to 180 °С slightly decreased up to 200 °С.

Most of the rangelands in Iran have been destroyed and a main part of rangeland plants are threeatened or their populations are reduced. In order to stability, reclamation of rangeland with adaptable species and finding the best cultivation method are of special priority. The present study was done to evaluate the stablishment percentage of Salsola rigida populations in different vegentation regions of Semnan provionce. Based on the results of reasearch project, seeds were collected and cultivated from different regions of the rangelands. For determination of population stablishment percentage, a randomized completelty block design were conducted in triplicate under farm conditions between 2013-2015 and the data were analyzed. Among the accessions, the genotype code 232 (originated from Chahakeh 6, Haj Ali Kavir) and 229 (originated from down road, Alay Village) had the highest and lowest stablishment percentage, respectively. Findings of the present research illustrated that genotype code 232 of S. rigida can be used for reclamation of rangelands in the study area.

Forest structure is one of the most important key components in the description of forest ecosystems and its biodiversity. In order to properly forest ecosystems management, indicators are required to obtain the most information about the current condition of the forest structure and monitoring its changes with the least cost and time. The purpose of this study was to investigate the structural diversity of beech stands using a set of quantitative indicators based on the closest neighbor including uniform angle indicators, mingling, distance to neighborhoods, and diameter and height differentiation in the regeneration and degradation phases were carried out in Darabkola forest, Mazandaran. Six one-hectare sample plots were established in regeneration and degradation phases (three sample plots in each phase). In each plot, nine subplots (each 900 m2 ) were dispersed at a distance of 30 m. The diameter at breast height, tree height, the distance and angle among trees were measured for the nearest beech tree to the center of the sample plot as the control tree and three neighboring trees at the nearest distance to the control tree. The mean of uniform angle indices, species mingling, diameter and height differentiation, and distance index were 0.54, 0.51, 0.38, 0.54, and 4.13 in the regeneration phase, while these values were 51.0, 33.0, 43.0, 35.0 and 44.5 in the degradation phase, respectively. Therefore, using data from structural quantization of untouched beech stands, it is possible to assess their development stages and the results of forest management activities.

The aim of the present study was to estimate the canopy water storage capacity (S) and ratio of mean evaporation rate from the wet canopy to the mean rainfall intensity ( E / R ) and the direct throughfall coefficient (p) of a Picea abies plantation in a semi-humid climate using the regression methods in Kelardasht, North of Iran. To measure gross rainfall (Pg), four rain-gauges were installed in an open space adjacent to the stand and throughfall (Tf) measured using the twenty rain-gauges which randomly located beneath the canopy cover. Rainfall interception (I) was calculated as the difference between Pg and Tf. Twenty-one rainfall events were recorded with a cumulative depth of 380.1 mm. The Tfand Tf% were recorded 48.8% and 39.6% of the incident rainfall on the cumulative-based and event-based (each Pg), respectively. Positive linear correlation was observed between I and Pg (r = 0.92) and logarithmic correlation was established between Tf% and Pg (R2 = 0.43). The mean value of p, S, and E / R were estimated to be 0.34, 2.15 mm, and 0.43, respectively. Awareness of p and S values can be applied for appropriate silvicultural treatments in forest stands with respect to climate and rainfall.

In this study, different produced extruded commercial fish feeds in Chaharmahal-V- Bakhtiari Province investigated with the aim of determining growth indices and carcass composition of fingerlings rainbow trout. Total of 3600 rainbow trout Juveniles with initial average weight of 80±2.4 gr, were subjected in triplicate to four diets of 1, 2, 3 and 4 and in a completely randomized design for 130 days. At the end of experiment, 10 fish (294.77.3 g) from each tank were randomly sampled and chemical carcass composition (i.e. protein, lipid, ash and moisture) were measured. The highest body weight gain and daily weight gain were calculated in treatment 1 compared to others (p<0.05). Food conversion ratio (FCR) were lower in both 1 and 3 treatments than other groups (p<0.05). The maximum crude protein of fish fillet was obtained in treatment 1 and the lowest was measured in treatment 2 (p<0.05), but the fat content had not any significant differences among treatments (p>0.05). The highest and lowest fillet ash percent was seen in treatments 1 and 2, respectively (p<0.05). Treatments 1 and 2 were contained the highest and lowest amount of calcium and phosphorous, respectively (p<0.05). In conclusion, growth performances and carcass chemical composition of rainbow trout were not similar which could be related different levels of crude protein of commercial diets, which produced in Chaharmahal-V-Bakhtiari feed factories.

The present study was carried out in Karun 4 Dam lake, Chaharmahal-v-Bakhtiari province with the aim of tropic determination and assessing some of the relationships between physical, chemical and biological properties of water from March, 2011 to 2012. Three stations were selected in the dam: one station near the dam wall and two stations at the entrance of Urmand and Bazoft rivers, respectively. Some of physicochemical properties of water including temperature, turbidity, hardness, temperature, pH, dissolved oxygen, biological oxygen demand, chemical oxygen demand, total soluble solids, total suspended solids, nitrates and phosphoric acid, as well as biological properties such as phytoplankton identification and counting, chlorophyll a were monthly evaluated. Based on the present results, 5 branches and 30 species of phytoplankton were identified with the most frequency of Bacillariophyta (17 species), Chlorophyta (6 species), Chrysophyta (4 species), Dinophyta (2 species), and Cyanophyta (1 species), respectively. The maximum and minimum chlorophyll a content were obtained in June (4.9 μg L-1) and its minimum in February (2.1 μg L-1), respectively. Findings of the current research showed that chlorophyll a concentration correlates with the temperature, while no correlation was found with the suspended solids (P> 0.01). On the other hand, chlorophyll a content and phytoplankton diversity showed a significant negative correlation with transparency, total nitrogen, and total phosphorus (P <0.01). The highest and lowest richness index was observed in summer (0.061117) and in autumn (0.058), respectively. The Simpson species diversity index was also reached to the highest and lowest value in spring (0.98889) and autumn (0.9905), respectively.

The present study was carried out in Karun 4 Dam lake, Chaharmahal-v-Bakhtiari province with the aim of tropic determination and assessing some of the relationships between physical, chemical and biological properties of water from March, 2011 to 2012. Three stations were selected in the dam: one station near the dam wall and two stations at the entrance of Urmand and Bazoft rivers, respectively. Some of physicochemical properties of water including temperature, turbidity, hardness, temperature, pH, dissolved oxygen, biological oxygen demand, chemical oxygen demand, total soluble solids, total suspended solids, nitrates and phosphoric acid, as well as biological properties such as phytoplankton identification and counting, chlorophyll a were monthly evaluated. Based on the present results, 5 branches and 30 species of phytoplankton were identified with the most frequency of Bacillariophyta (17 species), Chlorophyta (6 species), Chrysophyta (4 species), Dinophyta (2 species), and Cyanophyta (1 species), respectively. The maximum and minimum chlorophyll a content were obtained in June (4.9 μg L-1) and its minimum in February (2.1 μg L-1), respectively. Findings of the current research showed that chlorophyll a concentration correlates with the temperature, while no correlation was found with the suspended solids (P> 0.01). On the other hand, chlorophyll a content and phytoplankton diversity showed a significant negative correlation with transparency, total nitrogen, and total phosphorus (P <0.01). The highest and lowest richness index was observed in summer (0.061117) and in autumn (0.058), respectively. The Simpson species diversity index was also reached to the highest and lowest value in spring (0.98889) and autumn (0.9905), respectively.

This study was conducted to evaluate the effect of some cellulosic materials such as sawdust and alphacellulose (cotton linter) for purification industrial and urban wastewater and their effects on the absorption of some elements (No3, Na, K) and heavy metals (Cd, Cr, Zn). Due to very low amounts of chromium, cadmium and nitrates in the wastewater samples, the chromium and cadmium chloride solution with a concentration of 20 ppm and sodium nitrate solution with a concentration of 60 ppm were used. The results showed that among the absorbents, mixture of wood sawdust and alpha-cellulose had the same effect on sodium and zinc absorption compared to sawdust. Absorbents did not affect the potassium uptake from wastewater, but had a significant effect on the absorption of chromium and cadmium. The amount of chromium in the control sample was 27 mgL-1 to 3.76 mgL-1 after exposure to the sawdust absorbent and 4.4 mgL-1 in the mixture of sawdust and linter absorbent. The amount of cadmium decreased from 22 mgL-1 in control sample to 1.5 mgL-1 (coefficient of 93.18%) after exposure to the mixed sawdust and alpha-cellulose and 0.88 mgL-1 in sawdust treatment (coefficient of 96%). Absorbents had also no significant effect on nitrate absorption in sodium nitrate solution.