IRANIAN JOURNAL OF NATURAL RESOURCES
Year:2001 | Volume:54 | Issue:3|Papers Count:10

In recent years, landslide occurrence, due to change of forests into tea farms and construction of roads, has been on the increase in northern regions of Iran. The investigation of phenomena and factors, effective in landslide occurrence is vital and detern1ining susceptible zones for the purpose of preventing and avoiding the harmful consequences, is indispensable. There are several methods for landslide hazard zonation. In this research, the statistical method of multiple regressions was employed. For evaluation of accuracy of the model, a neighboring basin with similar lithology, land use, rainfall and other characteristics was chosen, the model being used for this basin. The results of the investigation showed that most recorded landslides in the area have occurred in zones marked as susceptible in the offered model. Therefore the use of the proposed and employed model for the study area was confirmed.

In this study, PC technique was used to reduce the number of spectral bands or spatial variables in a data set by finding their linear combinations. To apply the PCA for spectral/spatial data set, Landsat TM data recorded from 5 different areas in Central Iran, and 18 soil varaibales were used. The result of PCA transformation for TM bands revealed the importance of PC1 in soil studies, PC2 and or PC3 for vegetation investigations. The results of PCA for Landsat TM and soil data showed that the TM data of 7 bands and 18 soil variables v/ere mainly compressed to just three PCs that describe more than 90% and 55% of spectral and spatial information respectively. Based on the obtained results we may conclude that PCA can be applied to different sources of spectral/spatial data, for a better establishment of sampling plan and save in money and time.

In order to study the using of stratification inventory method for volume estimation in Kheyroodkenar forest, the cost and precision of systematic random sampling and stratification method were compared in Patom and Namkhaneh districts. First, the forest, based on crown density, was stratified on aerial photographs and then inventoried with systematic random sampling method. Also the time used in aerial photographs lab for stratifying the photos and in the field for measuring the sample plots were recorded. After stratification and measurement, the time-cost and precision of each method were calculated. The numeral values of precision2xTime -cost (E2%xT) were used to compare these two methods. The results showed that the stratification.

The study was carried out with 3200 viable seeds. The experiment was based on a completely randomized design of four treatments (factors) and four replications. Seeds were planted in depths of 5cm in plastic pots. The four treatments were as follows: (A): Seeds maintained outdoor for a month, then planted in pots, (B): Seeds planted immediately after harvesting, (C): Seeds maintained in refrigerator for a month in temperature of 1-5°c, later planted, and (D): Seeds wetted for 48 hours then kept in temperature of 1-5°c, later planted. Data analysis indicated that the treatments were significantly different. A comparison of seed germination means, based on Duncan Test, was made, according to which four treatments were fitted in two classes. Class (a), included treatments (B), (C) and (D) with germination percents of 95.5, 97.38 and 98.5, respectively. Class (b) consisted of treatment (A) with a germination percent of 23. According to the results, and from an economy point of view, treatment (B) is the most suitable process and way to be employed in reviving the Oak forests of western Iran.

In this study a process oriented model of the JABOWA tree growth model was verified to simulate and to predict tree growth in hypothetical climate resulting from global climate change scenarios. Based on literature, four treatments were applied, normal temperature, and increases of 1, 3 and 5°c. First JABOWA was calibrated for Norway spruce (Picea abies (L.) Karst) and Red pine (Pinus resinosa Ait.) using the weather data from 1953 to 1992. Comparison of basal area increment of both species for last (1983-1992) and the next (1993-2002) ten years showed that there were no significant differences when temperature was normal or increased by 1 and 3°c but it was significant (P<0.001) when temperature increased by 5°c. Treatment effects were negative on the growth of both species, except for normal and 1°c. Red pine grew. More than Norway spruce when the mean temperature was increased by 1, 3 and 5°c. It was concluded that Norway spruce was more likely to decline than Red pine if global warming occurs.

In order to study the ecological conditions of Wild cherry (Cerasus avium) in the forests of north of Iran, eight regions in these forests from Asalem in Gilan to Lowe in Gorgan, were identified and selected. Qualitative and quantitative characteristics were evaluated. The study of soil and climate conditions was performed too. The results indicated that Wild cherry was distributed from west to east and from lowlands to uplands of Alborz region, but the stands in midlands (altitude 900-1400 m) were denser. The species were distributed on the northern, northwestern, northeastern, western, eastern, southeastern, and southern slopes, but at northern, northwestern, northeastern, and eastern ones the density was higher. The slope gradient in these areas varied from 0 to 90 percent. Various vegetation types in study region consisted of Cerasus avium-Cerasus betulus, Cerasus avium -Acer velutinum, Cerasus avium-Acer cappodicicium, Fagus orientalis-Cerasus avium, Carpinus betulus-Cerasus avium, and Acer velutinum-Cerasus avium. Quantitative studies showed that from the point of frequency, density, basal area and volume per hectare, the Chenes forest exhibited the best condition. Qualitative studies showed that Siahbil was the best site and Lalice the worst. Totally, Chenes was Shown to be the best site and Lalice the worst. Climatological studies indicated that the distribution of Wild cherry was in the areas with an annual mean precipitation of between 867 and 1968 mm/year, and an annual mean temperature of 7.1 to 13.6°C. Soil studies showed that Wild cherry grows on brown forest, washed brown, dark brown pedolic, autotroph brown and hydromorph brown soil types with textures including loamy clay, silty loam, sandy clay and sandy loam. Soil pH varied from 5.2 to 7.1. Most of the soils were deep to moderately deep, suitable for rooting.

To determine the possibility of polystyrene waste utilization in particle board manufacture, one layer laboratory panels with two variables of glue in five levels of 0, 2.5, 5, 7.5 and 10 percent- and polystyrene in five levels of 0,5,10,15 and 20 percent were produced. Physical and mechanical properties of test panels were measured. The results showed that increasing the glue content improved all physical and mechanical properties of panels. The results also indicated that the amount of polystyrene had significant influence on the panels' physical and mechanical properties-except for shear strength. According to the results, the best physical and mechanical properties of panels were obtained when using 10 percent glue and 15 or 20 percent polystyrene, but there were not any significant differences found between physical and mechanical properties of those panels and panels when using 5 percent glue and 20 percent polystyrene. Moreover no significant differences were observed between properties of reference panels and panels with 5 percent glue and 20 percent polystyrene. Therefore it can be concluded that with 5 percent urea resin and 20 percent polystyrene, proper quality panels can be obtained and the resin consumption will be reduced.

In this research, the fixation speed of 2% Celcure preservative (ACC) salt, under temperatures of 17, 27 and 50°c, on intact and stained wood specimens of Beech was investigated. For this purpose, wood blocks of 5×5×7 cm dimension were prepared and saturated with 2% ACC using full-cell process. The specimens were placed in three incubators of the above-mentioned temperatures. For measuring the percentage fixation through time, extracts of specimens were obtained, using hydraulic pressure of 69 Mpa. The pH of extractions was measured using Diphenyl Carbazid method and a spectrophotometer. Measurements were made continuously while the amount of 6-valency chromium present in the extract being compared with the amount of chromium concentration in the primary solution. The percentage fixation was then calculated. The results indicated that a decrease in 6-valency chromium is accompanied with an increase in pH, this being due to absorption of positive hydrogen ion by 6-valency chromium to be reduced to 3-valency chromium as well as ion-exhange of active components with wood during the primary phase of fixation. Time necessary for reaching complete fixation in intact and stained wood in the fixation temperature conditions of 17, 27 and 50°c were 1075, 501 and 109 hours respectively. In general, it was shown that temperature has an effective role in accelerating the fixation time, while in this process, intact and stained wood did not exhibit a significant statistical difference.

Ten selected fungi from Ascomycetes and Deutromycetes were used for evaluation of oil degrading and surfactant producing capability. High correlation was observed between mycelium growth and surfactant yield in oily medium (4% v/v) indicating the capability of fungi in degrading oil and Denovo synthesis of surfactant.