IRANIAN JOURNAL OF NATURAL RESOURCES
Year:2003 | Volume:56 | Issue:3|Papers Count:17

The objective of this study was to define different erosions types in the drainage basin of Masouleh Rudkhan and to determine the rate of erosion and production of sediments. The factors affecting erosion such as phsiography, topography, climatic condition, hydrology, geology, geomorphology and vegetation were investigated. This drainage basin has an area of about 227.72 km2. Based on the geomorphological survey, 3 joints, 18 geomorphological faces and 229 primitive joints could be determined. The rate of erosion and sediment production of every work-joint were studied, employing geomorphological units (qualitative) and E.P.M. method (quantitative). The sub-drainage basin number 4 showed the highest erosion rate (2.1) and the largest sediment productions (94081 m3). This is due to the effects of slope and low resident of shale, clay and silt as well as the change of land use and. The sub-drainage basin number 8 showed the lowest rate of erosion (0.69) and sediment production (12297.5 m3) owing to the natural resistance of such stones as diorite, gneiss and gabbro. The results showed that in every geomorphic unit, the resistance of stone against erosion was the most important parameter and that the most important eroding factor was the change of land use and forest destruction. Furthermore, there was a logic relation between the geomorhological units and the rate of erosion. Thus, the use of E.P.M. model in this case was found to be appropriate and logical.

In water resources management and flood forecasting, making reliable predictions become crucial. There are many ungauged watersheds in arid and semi-arid regions of Iran that need suitable method to estimate peak discharge. One of the methods for flood frequency analysis in arid and semi-arid regions is Hybrid Method. This study was carried out to evaluate Hybrid Method for estimating peak flows in east and northeast of Iran and compare this method with index flood method. At first, the test regional distribution function (Log Pearson) was fitted and inststaneous peak discharges with different return periods were calculated. Using factor analysis the independent and important variables were determined. These factors include: area, mean elevation, drainage density and annual average rainfall. At the next stage, two regional hydrologic models were obtained and hydrologically homogene areas were determined with cluster analysis of data for Index flood Method. According to Hybrid Method, the classification of groups was taken on the basis of area of each watershed and three homogene regions with various areas were determined. Comparison of Hybrid Method with Index Method in Sheshtaraz station showed that only in return periods higher than 10 years, Index Method gives more accurate results. But in two other stations (Frizi and Shast-dareh), the results Hybrid method in all return periods showed more accuracy comparing to index Method.

In this study, processing of satellite images derived from T.M. sensor was used for soil studies and finally for producing soil units map. The region is part of Varamin plain and watershed catchment of Jajroud River. According to the nearest weather station information, average of yearly rainfall of study area is between 140 and 150 mm with average temperature of 18°C. Based on two different methods, soils of this region can be classified based on soil taxonomy method (i.e., two Aridisol and Entisol orders) and based on F.A.O. method (i.e., mainly as Fluvisol, Cambisol and some units as Calsisol, Gypsisol and Solonchak). Agreement ratio between soil maps derived from digital classification with the maximum likelihood method and ground truth map devolved from traditional methods and its kappa index were 82% and 75%, respectively. Analyzing the error matrix of this research showed that among 12 units derived from this study, differentiation of units 2 from 6 and 9 from 7 were poor (i.e., units 2, 6, 9 and 7 correspond to Haplocalcid, Haplocambid, Calcaric Fluvisol and Calcaric Cambisol, respectively). Meanwhile, the presence of high silt content in the texture of topsoil created high spectra reflection, which caused great similarity of the spectra with saline soils or other chemical substances. This resulted in some problems when analyzing dates and specially image classification. This research suggests that in soil studies, beside selection of suitable spectral bands, images be used when land is bare. It should be noticed that images of the land with and without plant coverage can be used simultaneously, too. To reduce the above-mentioned interference, in stead of classifying based on the difference in spectra reflection, digital dates produced by other sensors, such as SPOT satellite (of France) or IRS satellite (of India) and also other classification methods based on phenomenon coordinate system should be studied.

One of the most important information in urban forestry is the knowledge of their areas. Nowadays, for this purpose, different methods are used in different countries. In tis research, the firest one carried out in Iran, different sampling methods including 100% inventory with 10-meters strips, simple random sampling, randomized block sampling, systematic random sampling, two stage sampling and dot grid sampling using the aerial photographs, were used to obtain the areas covered by street trees. The study area was valieasr Avenue in Tehran (right and left side of 5000 meters of the avenue with 500 transects). The largest length of tree s crown (Which is the same as strip s width that were at the beginning point of any strip or the nearest) were measured by 100% inventory (the comparison base for other methods). Strip s areas were calculated using the largest crown length for each method 50 strips were selected and the measurements were carried out and analyzed. Normality of data were tested by x2-test and t-test was used to determine the difference only block random sampling had difference between each different sampling had difference, there for T× E2% value was calculated for other methods. Results showed that dot grid sampling is the best inventory method in urban forestry.

During last two decades, deforested areas have been increasing in Caspian region in north of Iran due to human destruction. Litter decomposition, nutrient cycling and shortening of ecosystem recovery could be a suitable approach in addition to afforestation with ameliorating species for rehabilitation of disturbed Caspian forests. This study was conducted to determine the abundance of millipedes within 14 years old afforestation stands of maple, oak, alder and cypress in comparison with a nearby disturbed stand of ironwood-hornbeam in Darabkola (Mazandaran, Iran), with particular attention to nutritional elements composition of litter. A total of 50 samples of litter layer were taken for abundance and biomass of millipedes. Such chemical properties of litter and soil as dry weight, organic matter, crude protein, crude lipid, crude fiber, ash content and pH were analyzed. Simultaneously, equal samples were chosen from topsoil layer (0-10 cm) to measure moisture content and bulk density. Mean biomass of millipedes was over 100 mg/m2and mean dry weight of litter was less than 1000 g/m2 in afforestation stands of maple and oak. In contrast to the above mentioned afforestations, these parameters were under 50 mg/m2 and over 1000 g/m2 in other study area. Number and biomass of millipedes had significant correlations with dry weight (r=-0.88), crude lipid (r=0.80), crude fiber (r=0.53) and bulk density (r=0.60). However, crude fiber had by far the highest correlation with the first axis of the PCA (r=-0.69). Abundance of millipedes and litter accumulation was significantly influenced by the tree species planted in afforestations through nutritional composition of litter.

Since Agroforestry study is very limited in Iran, identification of traditional systems was necessary in order to develop a basis for such studies particularly in Kohkiloieh and Boyerahmad province, which has special situation. To achieve the objectives of this study, many travels were done throughout the whole province and important systems were found and their characteristics were recorded. The Carlowitz method (1989) for standard characterization of Agroforestry technologies was used as a base to characterize the information of these systems. However, this method was not very detailed nor completely compatible to the present situations in many cases. Thus, Carlowitz principles were extended and a new method was developed which was corrected in an irritable process, and the systems were characterized. The book entitled Characterization, Diagnosis and Design, which provides some more insight on ICRAF s (International Center for Research on Agroforestry) approach to characterize land use, was also used for developing the method. The systems studied in Kohkiloieh and Boyerahmad were classified according to Nair (1985) who classified the Agroforestry systems to three major groups based on nature of components. Then, the systems were reclassified according to the climatic and ecological conditions as well as to the level of technology and Socio-economic criteria.

In order to study the chestnut seedling production, this project was carried out in Caspian forest seed center, north of Iran. 60 kg seed were gathered from 30 trees in Vissrood forest in Gilan province. After sterlizing the soils with Methylbromide antifungi in tow conditions (shaded and unshaded) with 5 treatments and 4 replication (Randomized complete block designs) after cress test, seeds were sowed on early October in 2001. Each replication have consisted 225 pots (5×45 pots). Treatments 1-4 were included: decayed tea leaves, loam soil, rice bran and sand with different compositions, and treatment 5 (control) was natural forest soil from investigated chestnut site. Analysing of variance with Duncan s test (Duncan s new multiple range test) on different characters consist of seedling vitality , height and collar diameter showed that significant difference at 1% level have been obtained between control treatment and others . Meanwhile no differences were obtained in other treatments. In other words, shaded condition with forest soil treatment showed best results.

To study the effect of lac-balsam preservative on preventing fungal contamination of trees, 30 trees of Platanus orientalis and 16 trees of Pinus eldarica at the faculties of agriculture and natural resources area (Karaj, Iran) were selected as sample. These samples were selected from identical environment and growth conditions, with the same age, height and diameter of trees. Two circular pieces of 6cmdiameter were cut from each tree stem at the breast height (i.e., 1.5 m from the ground) till the cambium layer was reached, removing the bark. One of these pieces was treated with lac-balsam preservative, but the other one was left on the stem without any chemical treatment (as control). Samples were selected and cut during the second half of March 2001 (beginning of plant growth), and samples were collected back from the stems in mid November 2001 (end of plant growth). Results showed that from the standpoint of fungal contamination, there was a significant difference between the two species, where the plane tree was found more sensitive (susceptible) to the fungal contamination. Also, there was a significant relation between the tree species and fungi species, e.g. Moniliaceae was observed more often in plane tree. It was also found that type of cutting (open and close) would not determine the level of fungal contamination.

In this study, the possibilities of using three different chemical substances as fire retardants for Iranian maple wood (Acer insigne Boiss) was reviewed and fire resistance properties as well as mechanical and physical properties of samples impregnated with these chemicals were tested. These results were finally compared with the control samples. Independent variables and their levels are as follows: - Fire retardants: 1) mixture of mono ammonium phosphate and borax (MPH+BX), 2) minalith, and 3) pyresot.- The concentration of fire retardants: 5.8 and 12%.- The diameter of burner: 2.3 and 5 mm. Preparation of samples and measurement of fire resistance properties were done according to JISA- 1322 and BS 476 Standard, respectively. The percent of weight loss, flame point, duration of flame after removing the burner, time of glowing after taking the burner off, and the percent of carbonization. On mechanical and physical properties, compression parallel to the grain, static bending and the percent of total shrinkage were tested.Considering the weigh loss, the result shows that samples impregnated with minalith and pyresot had respectively the least and the most weight loss while treatment with MPH+BX mixture had a weight loss close to minalith-treated samples. On other fire resistance properties, it was found that among the three different chemicals, MPH+BX mixture provided the best results.In all measurements, it was observed that the samples impregnated with MPH+BX mixture had the highest mechanical resistance in comparison with the untreated (control) samples. As expected, treated samples had more total shrinkage in comparison with control samples.

In this study, bark of alder (Alnus subcordata) and oak (Quercus castanifolia) were extracted by 1% alkali (1:10 w/v) at 90°C for one hour. Net yield of extractions were 21.44% for alder and 24.07% for oak. According to Stiasny number obtained for alder (90.28) and oak (70.02), the value of active polyphenolic compounds for the two species were estimated to be 19.35 and 16.85%, respectively. The amounts of condensed tannin were determined by column chromatography packed with sephadex LH- 20 and found to be 6.3% and 4.2%, respectively. The results showed that condensed tannin in alder is 50% more than that in oak. The hydrolysable tannins (gallotannin and ellagitannin) were also estimated by spectrophotometry method. The high amount of ellagic acid in oak and alder extractives (respectively 43% and 35.3%), indicates that most of the tannin in these species are hydrolysable. In general, the bark of oak and alder contained 21% and 6.9% tannin, respectively.

To investigate the effects of provenance and age variations on wood properties of eastern cottonwood (Clone 77/51), disks were cut at the breast height of 12 eastern cottonwood trees, collected from Gillan (Safrabasteh) and Mazandaran (Chamestan) research projects by a random sampling method. Average growth rate of Chamestan trees was the highest because of better conditions of the provenance (e.g., soil, temperature, etc.). Age caused more variation in fiber dimensions. The highest fiber length mean was 0.995 mm for 18 years old Safrabasteh trees. Optimum age for tree harvesting of this clone was found to be 9-10 years by statistical analysis method. Variation in tree age had statistically significant effect on oven dry density, but it did not have significant effect on basic density. Provenance variation did not bring about significant differences in chemical composition, except in cellulose content. The results also showed that variation in tree age had more effects on wood characteristics of this clone than variation in provenance.

This research was conducted to investigate the possibility of producing particleboard, utilizing self-bonding techniques and applying cross-linking agents of natural polymers. P. deltoides particles were separately treated with two oxidizing agents, i.e. nitric acid and hydrogen peroxide at 3% each. Then, a cross-linking agent such as 1,6-hexanediamine glycerol, black liquor, or maleic anhydride at 5% (O.D. wood basis) was added to the particles in order to facilitate wood bonding. Laboratory boards at 0.75 g/cm3 density were produced; then, physical and mechanical properties were determined and compared with the control specimens. The result of this investigation showed that treatment with nitric acid, 1,6-hexanediamine or black liquor improved these properties. The modulus of rupture and internal bonding of the boards were 21.82, 21.06 and 0.461, 0.422 mPa, respectively; and the dimensional stability was reasonably good. In addition, the boards made using nitric acid treatment had better properties when compared with the hydrogen peroxide treated samples, but it was not as good as the control specimen (made using 5% phenol formaldehyde).

Range improvement through planting non-native and adapted species requires more studies on their several different aspects. Ecological positive or negative effects on new species must carefully be examined before allowing their plantation in vast areas. The aim of this research was to determine the ecological effects of Atriplex lentiformis species on vegetation cover and soil in two sites in Fars province. The research method was based on comparison between selected control plots and planted sites. Annual production (dry matter), canopy cover and density of Atriplex shrubs were measured. Plants were compared in terms of dry matter production per hectare as well as canopy cover percentage by F-test at 95% level within the two sites. Canopy cover percentage for I, II and III species class was compared between shrubs and control sites using F-Test. Abundance of species was compared by KS test. Results show that there was no significant difference between the two sites in terms of dry matter production and canopy cover percentage. Canopy cover percentage in planted areas was greater than the control area. In planted area, the number of class I and native species was more than control species. Statistical data of vegetation in Dadin Kazeroon region was similar to Konarhaji Darab’s except that in Dadin Kazeroon, there was no significant difference between canopy cover percentage of the control and planted areas. From the results obtained on both geographical regions, it can be concluded that Atriplex did not have a negative effect on vegetation, but increased the percentage of class I species in the planted areas.

This study was carried out to investigate the relationship between environmental factors (including climate, soil and topography) and establishment and expansion of rangeland plant types on north and north east areas of Golestan province. On the basis of fieldwork, 23 ruling vegetation types were identified and the effective environmental factors were investigated. On each plant type, the soil profile was dug and the soil samples were taken from 0-30 cm and 30-60 cm depth. The soil factors that were analysed comprised of texture, SP, EC, pH, PSP%, CEC, N, K and P. For analysis of soil factors, the USDA standard method was used. Such topography factors as elevation, aspect and slope and also rainfall and the critical water table depth were calculated for each vegetation type. Using Kovda formula, the critical water table depth was calculated. The multivariate analysis was used to determine relationship between vegetation types and environmental factors. A matrix of vegetation types and environmental characteristics was prepared, and the ordination of vegetation and environmental factors were done by the Principal Component Analysis (PCA) using PC-ORD software. The results show that the environmental factors affected vegetation establishment and expansion. The most important factors that influenced vegetation type s separation were as followe: water table depth, aspect and soil salinity. The multivariate analysis explains the effects of complicated environmental factors on the plants by means of a simpler way, introducing one or more important factors.