IRANIAN JOURNAL OF NATURAL RESOURCES
Year:2002 | Volume:55 | Issue:3|Papers Count:14

Effective discharge for suspended sediment was determined in Zayandeh-rood Dam Watershed stream using available discharge and suspended sediment records. During the record length of 6 to 21 years, the drainage area for these stream basins varied from 321 to 1,444 km2. Effective discharge was determined using suspended sediment load and daily means discharge obtained from each station for each water year of the period recorded. They were grouped in several classes in term of size and then plotted as histogram. The discharge increment with the largest cumulative load taken to be the effective discharge. The results showed that the magnitude of the effective discharges and their duration were different. It is apparent from these data that the effective discharge for suspended sediment transport might be in many cases low magnitude event. The duration of the effective discharge, which was calculated using flow period record, was different in various stations. The average values ranged from 28.5 to 58.05 percent.

In this research, lithologic-geologic characterstics and the relationship between lithology and pedology of the studied area were investigated. The area studied consists of six chosen watersheds of the Taleghan Drainage Basin which are located in 50° 20' to 51° 10' longitudes and 36° 05' to 36° 23' latitude. The six sub-catchments were chosen in such a way that every two of them were located against each other and in opposite geographic aspects. The area is located in Alborz geological zone and in central Alborz sub-zone. From the view point of seismicity, the area is active. The major faults of the area are Taleghan and Kandevan faults and a few other minor ones. Some branches of these faults are present in the area. Stratigraphically, from the oldest formations (belonging to pre-Cambrian) to the youngest formations (belonging to Quaternary) are present with diverse lithological characteristics. In the area, sedimentary rocks and evaporites outcrop. Igneos rocks are widespread. Extrusive igneous rocks consist of pyroclastics and lava flows. Intrusive igneous rocks are also present. In this paper, by photogeologic investigations and field checks, geology and lithology maps of the watersheds with the scale of 1:25000 were prepared. Then, several soil profiles were made on each lithologic unit from which soil samples were taken. Soil samples were then analyzed in the lab. The results of these analyses show that soil characteristics were dependent on chemical and physical properties of parent rocks. The soils formed on limestones had high percentage of CaCO3, alkaline pH and low EC. Soils formed on evaporitic marls had clayey texture, relatively high CaCO3% and EC, and alkaline pH. The Soils formed on acidic (Sialic) igneous rocks had acidic pH, and very low EC and CaCO3%, and mainly sandy texture. Soils formed on intermediate igneous rocks had neutral pH of 7 and low EC and CaCO3% and predominately sandy texture. Soils formed on igneous rocks had a pH of 7.225, intermediate to high CaCO3%, low EC, and predominately sandy texture.

Southern areas of Bafgh are located in central arid areas of Iran, with little amounts of precipitation and vegetation cover. Blowing of strong wind over these bare areas causes wind erosion and destroys soils texture, which result in rail roads damage specially Tehran-Bandar Abbas in southern Bafgh and also in damage to farmlands and neighboring villages. By accumulation of moving sands in southwest Bafgh, an erg of 37 km2 areas was made. In order to control wind erosion in these areas, source of aeolian deposits were determined using stepwise determination method. Investigations showed that erosive wind blew from southwest and transported aeolian sands, depositing them on sand dune areas. Geomorphological studies and mineralogy showed that source of sand dunes were local and near them, including some part of pediment in southwest of erg, Zarand Shoor dry river, and wind erosion facies in these areas. Generally, the main source of aeolian deposits extended from sand dune areas to Zarand Shoor dry river, and secondary source sandy desert nearby.

In order to identify the plant ecological groups and to determine their distribution patterns in relation to soil physical and chemical characteristics and physiographical-features, vegetative elements and some soil properties were analyzed in submountain forest in north of Iran. This research was conducted in an area of 8 hectares at the altitude of 690-800 meters above sea level in Neka forests. For identification and classification of vegetation cover, 214 grid plots of 100 m2 were chosen on the basis of Braun-Blanquet combined abundance cover scale. Plant ecological groups were determined on the basis of vegetation data analysis (i.e., TWINSPAN) and ordination analysis (i.e., DCA) methods. Geographic information system (GIS) was used for mapping plant ecological groups and Digital Elevation Model (DEM). Comparison between plant ecological groups and slope, aspect and elevation maps showed that significant differences existed between plant groups and aspect, but there was not any significant relation between plant groups and slope or elevation. Ordination analysis was carried out using DCA in order to find out the floristic composition of ecological groups and samples. To investigate the relationship between ecological plant groups resulted from TWINSPAN method and physical-chemical characterizations, soil samples were selected from organic horizons and mineral layers. Soil characteristics including organic matter, moisture, , lime و bulk density, C, N, P and K were used for analysis by PCA method. Results of PCA analysis indicated that the first group, namely Parrotia persica, Cerasus avium and Ficus carica, was related to soil physical properties. The second group, including Danae racemosa, Asplenium adiantum-nigrum and Cardamine impatiens, corresponds to soil fertility, particularly soil chemical propeties. The third group, including Diospyrus lotus and Oplismenus undulatifolius and also the fourth group, Cyclamen coum, Lamium album and Galanthus transcaucasicus, were related to soil fertility.

One of the principles of forest management is recognition of forest parameters such as forest classification. This research was carried out for ground truth mapping of forest types in order to study possibility of forest classification using satellite data (ETM+). Until now, forest typing has only been done based on species frequency. As thick trees have high dominance and share in forest canopies, 100 thick trees in each plot were selected for forest typing in this research. The study area was 2170 ha in the Patom, Namkhaneh and Gorazbon districts, Kheyroudkenar watershed. In sampling method, 193 plots of one hectare area were selected. Each plot was sub divided into four sub-plots and data were collected individually. Percent of species frequency were computed for each sub-plot and plot and were then classified. Concerning to aware of low stratification of special types through satellite data, two typing methods were used, i.e. general and special types. In the general typing, three types were considered: pure, dominant species and mixture types. In the special types, those types were componened with two dominant species, were subdivided to details types. Six general and fifteen special types were finally recognized. Comparison of general types of total trees frequency method and 100 thick trees frequency showed that they were similar about 71 percent. Also, the best sample size for sample forest typing was found 0.5 ha for such forests.

The Sefid-Kouh protected area is situated 67 km to the northwest of Khorram-Abad. It covers an area of 69500 hectares. Much of the area contains a mountain system between 1500-2854 m altitudes. The aim of this research was to identify the plant species, introducing the flora, determination of life forms, and geographical distribution in central part of the Sefid-Kouh protected area. For this purpose, plant samples were collected from different parts of the area during two growing seasons between 1997-1998. The biological spectrum of the area was plotted by means of life forms results. The position of the protected area within Iran’s phytogeography classification was studied based on geographical distribution data and references. From a total of 148 species and subspecific taxa, 1 fern, 115 dicotyledones and 32 monocotyledones were identified. Among the 47 families represented in the area, the followings had the highest number of species: Asteraceae, Liliaceae, Lamiaceae, Rosaceae and Poaceae. 98 species (66.2%) were endemics of Irano-Turanian region, 17 species of them were endemics of Iran. Distribution of the following species is mainly limited to Zagros area: Alcea koelzii, Amygdalus elaeagnifolia, Arum giganteum, Centaurea phlomoides, Dionysia gaubae, Pyrus glabra, Quercus brantii var. persica. Hemicryptophytes, geophytes and therophytes with 52 species (35.1%), 37 species (25%) and 33 species (22.3%) were respectively the most frequent life forms of the protected area.

The Sefid-Kouh protected area is situated 67 km to the northwest of Khorram-Abad. It covers an area of 69500 hectares. Much of the area contains a mountain system between 1500-2854 m altitudes. The aim of this research was to identify the plant species, introducing the flora, determination of life forms, and geographical distribution in central part of the Sefid-Kouh protected area. For this purpose, plant samples were collected from different parts of the area during two growing seasons between 1997-1998. The biological spectrum of the area was plotted by means of life forms results. The position of the protected area within Iran’s phytogeography classification was studied based on geographical distribution data and references. From a total of 148 species and subspecific taxa, 1 fern, 115 dicotyledones and 32 monocotyledones were identified. Among the 47 families represented in the area, the followings had the highest number of species: Asteraceae, Liliaceae, Lamiaceae, Rosaceae and Poaceae. 98 species (66.2%) were endemics of Irano-Turanian region, 17 species of them were endemics of Iran. Distribution of the following species is mainly limited to Zagros area: Alcea koelzii, Amygdalus elaeagnifolia, Arum giganteum, Centaurea phlomoides, Dionysia gaubae, Pyrus glabra, Quercus brantii var. persica. Hemicryptophytes, geophytes and therophytes with 52 species (35.1%), 37 species (25%) and 33 species (22.3%) were respectively the most frequent life forms of the protected area.

With goal on reducing demand for large diameter logs to cut standard ties out of them and also improving life expectancy of ties through improved treatment, dowellaminated cross-ties were designed and for practicality evaluation were fabricated. Required half-ties for this study were cut from residues of beech & oak logs which were being cut to produce conventional ties in a saw-mill that manufactures ties only. Each half-tie had a cross-section of 12.5×15 centimeters and a length of 2.6 meters. Totally, 48 half-ties were cut and stickered to dry in a shelter. Standard ties, cut simultaneously with half-ties, were also stickered in the vicinity to estimate their drying time and to evaluate degrading rate as well. After a 95-day period, moisture content (MC) of beech half-ties lowered down to 24% and that of oak to 35% while MC of standard ties was about 31% on average. Twenty dowel-laminated cross-ties were fabricated (by bolting together), weighed and impregnated under conventional treating process in a cylinder simultaneous with conventional ties. 15 beech and 5 oak standard ties were also weighed prior to treatment. After impregnation, both dowellaminated and standard ones were reweighed to calculate retention of preservative in them and an increment core taker samples were taken for penetration comparisons. In beech dowel-laminated ties retention was calculated to be 266.5, in oak 100 and combined beech–oak 177.5 kg/m3. The increment core samples showed that half-ties were impregnated thoroughly, but in standard ties this was not deeper than 5 mm. This would indicate that dowel-laminated cross-ties should last in service longer than conventional wooden ties if their mechanical connections do not fail. This is because they are less susceptible to end split checks and split; thus, they-will not decay as fast as those containing untreated wood in their core part.

To analyse the bark extractives, samples from five Iranian hardwoods trees such as black walnut, oak, alder, hornbeam and beech were prepared. Experiments showed that the total extractive content of these species were 29.8, 23.2, 17.9, 16.8 and 16.7 percent, respectively. The total ash content was 19.2, 11.5, 9.5, 12.8 and 13.8 percent, respectively. Also, it was shown that the total phenolic materials were 26.3, 21.2, 13.6, 12.9 and 14.0 percent, respectively. By sequential precipitation, flobatanins, flobaphens and flavonoids were separated and measured quantitatively. Also, the percentage of tannins was found to be 40-50% which is less than those of softwoods (50-60%); this means that the non-tannin extractives of hardwoods are more than those of softwoods. The lipophilic compounds of barks were determind quantitively using gas chromatography. Also, the chemical structure of a number of these compounds was suggested using GC-MS techniques.

An investigation of fabricating cellolusic fibers-polymer composite using recycled polystyrene and waste newspaper was conducted. Today, recycling of polymers is very important because of undegradability of polymers and economical considerations. In this study, samples were prepared from paper fibers and polyestyrene, where recycled newspaper fiber was mixed with recycled polystyrene at different levels (i.e., 10, 20 and 30% by wt.). Maleic anhydrided (MA) was added as coupling agent at 0, 1, 2 and 3% by wt. Mechanical properties of the composite were studied. It was found that adding MA increased the tensile strength. With increasing paper fibers, elastin modulus increased. The highest notch impact strength was obtained in sample which contained 20% paper fibers and 2% MA.

The aim of this research was to study the relationships between soil characteristics and vegetation in order to find the most important characteristics for classifying of the vegetation types in Poshtkouh rangelands of Yazd province. After delimitation of the study area, sampling of soil and vegetation were performed using randomized systematic method. Vegetation data including density and cover percentage were estimated quantitatively in each plot; and with the help of two-way indicator species analysis (TWINSPAN), vegetation was classified into different groups. The topographical conditions were recorded for plot locations. Soil samples were taken at 0-30 cm and 30-60 cm depths in each plot. The measured soil variables included texture, lime, saturation moisture, gypsum, acidity (pH), EC, SAR, and soluble ions (Na+, K+, Mg2+, Cl-, CO32- , HCO3- and SO42-). Multivariate methods, including principal component analysis (PCA) and canonical correspondence analysis (CCA), were used to analyze the collected data. The results showed that the vegetation distribution pattern was mainly related to such soil characteristics as salinity, texture, soluble potassium, gypsum and lime. Generally, each plant species depending on the habitat conditions, ecological needs and tolerance shows a significant relation with some soil properties.

Saxuals (Haloxylon spp.) is one of the most important xerophytes and one of the best plant for sand stabilization in salty deserts. Insect pests, diseases and environmental factors restrict the reproduction and growth of saxual in nurseries of Yazd province, Iran. Surveys of 1998- 2000 showed that damping off and root rot were the most destructive and prevalent diseases in saxual nurseries. In order to determine the causal agents of damping-off and root rot, several samples were taken from nurseries. Infected plants indicated symptoms on root and crown. Isolation were done by planting pieces of discolored root and crown tissues on PDA and WA media and 189 fungi isolates were identified belonging to following six species: Fusarium solani, F. oxysporum, F. culmorum, Pythium aphanidermatum, Alternaria alternata and Rhizoctonia fragariae. From a total of six species, the pathogenicity of four fungi,i.e. R. fragariae, F. solani, F. oxysporum, P. aphanidermatum were observed in greenhouse. Symptoms of disease appeared on root system of saxual seedlings 21 days after inoculation. The pathogenic fungi were re-isolated from the infected seedlings. The sauxal plant is reported as a new host (Matrix nova) for these fungi: R. fragariae, F. oxysporum., F. solani, and F. culmorum (55%) with 105 isolates were found to have the greatest frequency and distribution among the pathogenic fungi studied. Anastomoses groupe of R. fragariae was identified as AG-G. In this investigation, using fungicide on media to induce teleomorph production in R. fragariae, of the fungus was not produced.