IRANIAN JOURNAL OF NATURAL RESOURCES
Year:2008 | Volume:61 | Issue:1|Papers Count:24

One of the methods for estimating sediment is using sediment data of hydrometric stations, and establishment of a relation between flow discharge and sediment discharge as sediment rating curves. Because of the importance of these curves in sediment discharge estimation and lack of sufficient data and information for most of watersheds in Iran, this research attempts to study variation trend of regional sediment rating curves and the effective factors, for use the obtained results for the other watersheds. Then 29 hydrometric stations with suitable geographic distribution were selected and their sediment rating curves were determined. Those stations were zoning into four climates, and in every zone, a regression relation was established between percentage of sensitive area to erosion, percentage of vegetation cover, and area of the basins with slope of curves. This relations were significant in 95% level of confidence in humid climate, 99% level in semi humid and 90% level in arid climate, this results showed the effect of this variable on slope of curves, but this situation in the semi arid climate a significant relation did not occured.

In this research, six sub-catchments of Gorgan Drainage Basin having discharge and sediment yield data were chosen. Yearly sediment rates of each sub-catchment were calculated. Then by dividing yearly sediment yield of sub-catchments to Sediment Delivery Ratio (SDR), the amount of erosion of each sub-catchment was determined. Homogeneous work unit map of each sub-catchment in GIS environment was prepared. Then, the erodibility of consolidated rocks and formations (Selby 1980) and unconsolidated geologic materials (modified K parameter in USLE) was determined. For ranking the erodibility of consolidated and unconsolidated geologic materials in the specific range (Selby number), the method of distance between numbers was used. For comparing different work units from the view point of erodibility and sediment yield, based on qualitative erodibility grade and specific erosion amount of land uses, specific erosion of each homogeneous work unit was calculated by using presented relationships. The results showed that the erodibility grade of rocks is from 34 to 86 and of unconsolidated geological materials is from 13 to 22.3, Also specific erosion of different work units in sub-catchments is from less than one up to 500 t/km2/y.

Recognition of effective factors in mass movement occurrence and land slide hazard zonation is one of the most important measures in prevention and reduction of their hazards. In this research, first landslide inventory map of the area which was prepared using air photos with the scale of 1:20000 and 1:50000 and field works, was used. In this map 410 landslides were shown. Effective factores for land slide occurrence were recognized which are as follows: Landuse, geological formation, rainfall, slope, aspect and elevation. Landslide inventory map was quantified by giving percentages to each subfactor of above-mentioned factors.Fore doing this, all the factors that were quantified, were entered into Arcview software environment as quantified, descriptive tables. Here, all 410 landslides were entered into quantified, describtive tables according to the mentioned factors and subfactors. Then each factor and its quantitative number was prepared as raster map. This process was performed using extentional facilities of ArcView which is called "Extension Spatial Analyst". The raster maps of six factors with cellular resolation of 0.0014 meters, were added together, in order to obtain hazard zonation map. For evalution of hazard zonation accuracy and separation ability of the used method, landslide hazard maps were overlaid with vector maps of landslides inventory map and necessary changes of the considered factors were made. The privilages of this method is as follows: It uses actual data obtained from the field works; by using this method, effective factores in land slide occurrence could be identified; it can be performed in any area; and the accuracy of hazard zonation is dependent on the accuracy of informations gathered in the field.

The accurate prediction of discharge can be considered as a key aspect in an efficient water resources planning and management. As demands for additional water continue to increase, the need for efficient water resources management is evident more than before, especially in arid and semi arid regions. Thus developing of reliable river flow forecasting methods for on time operational water resources management becomes increasingly important. In this research Karkheh basin and some of its sub basins in southwest of Iran were selected as a case study, with respect to the importance of its high water supplies potential. In this paper stochastic time series analysis method was used to develop some river flow forecasting models. In this paper autoregressive integrated moving average (ARIMA), deseasonalized autoregressive moving average (DARMA) and Thomas-Fiering (TF) models were used, in addition to description of time series analysis procedure. The models were developed in five sub basins of Karkheh basin and their forecasting performance were compared based on mean absolute error and root mean square error of forecasting. The results have shown that ARIMA and DARMA models have more accurate result respectively. On the other hand, TF model has more error of forecasting and less accurate forecasting performance than two other models in the study area.

Because in the most cases separation of forest boundary with monotemporal images is not possible, this study was performed with multitemporal images in order to delineate Caspian forests boundaries in Iran (case study in Chaboksar). In addition to deciduous broad-leaved forests there are afforested coniferous evergreen stands, tea and citrus orchards, farms and orchards with deciduas species in the study area. Spot-HRG and Terra-ASTER images from two different dates (14.8.2002 and 28.2.2002) were selected for this study. Radiometric errors were negligible and geometric correction (orthorectification) was precisely applied using digital elevation model. Two images were registered with each other. After defining forest and non-forest classes, the suitable training areas were determined and revised. Separation of forest and non-forest classes was carried out by monotemporal classification, multitemporal classification, hierarchical and digital-visual hybrid approaches. In order to determine the accuracy of maps resulted from interpretation and classifications a ground truth (forest boundary) was prepared using surveying with GPS. The length of selected surveying route was 64.5 km. The results of different classifications were compared with ground truth and their accuracy was determined. Kappa coefficient for classification of growing season and leafless season images, multitemporal classification, hierarchical approach and digital-visual hybrid interpretation were 0.28, 0.43, 0.57, 0.62 and 0.71 respectively. The most and least accuracy were related to digital-visual interpretation and classification of growing season image respectively. Results showed that forest boundary can be separated from non-forests by multitemporal images with high and acceptable accuracy. Based upon knowledge, experiences and the current study it is strongly suggested that leafless season images accompanied by growing season image, should be used in updating process of topographic maps of Caspian forests in such region.

This study was done to evaluate the changes in bulk density (Db) of the 0-10 cm surface soil of skid trails in the Hyrcanian hardwood forests, Iran. The treatment involved running a rubber-tired skidder in three skid trails: Flat Skid Trail (STF), Skid Trail with Transversal Slope (STTS), and Skid Trail with Longitudinal Slope (STLS). Pre- and post-skidding activities, soil cores were collected at random points of upslope and downslope tracks of each skid trails to measure soil bulk density and moisture content. In general, mean bulk density of compacted soil in skid trails was significantly greater than that of undisturbed soil. A significant increase (P<0.01) in soil bulk density occurred during first six skidding cycles at the STTS and STLS, when the soil moisture content was about 30% and 35%, respectively. But on STF, the increase in bulk density was greatest during first twelve skidding cycles. Additional cycles, up to 6 (on the STTS and STLS) and 12 (on the STF) cycles, did not cause significant increase in bulk density. The severe soil compaction was concentrated on the STTS.

Point-center Quarter method is one of the distance sampling methods for estimating the plant density and canopy cover. For plant density measurements, two formulas, one by Pollard (1982) and the other one by the author (2006) have been developed. In this study, applicability of these formulas with regard to accuracy to estimate the density and canopy cover of Zagross Oak (Quercus persica) forestes in research and educational Forest of Higher Education Center  of Qasr-e Shirin (Kermanshah province) were examined. Firstly, 50 hectars of these forest areas was selected and the inventory of the population was carried out. Then, 50 systematic random sampling points for Point-center Quarter method in this area were measured and recorded. The results show that none of the formulas could provide an acceptable estimate based on ±10% accepted accuracy; even though, the our formula has more accuracy level for density and crown coverage for this kind of forests and it could provide an acceptable estimate for management works based on ±25% acceptable accuracy.

Poplar plantation is of the main plantations in Guilan province. Shading caused by the adjacent trees is one of the effective environmental factors affecting the growth and development of poplar seedlings in nurseries, pest population densities and epidemics of pathogenic agents on poplar. During the years 2001-2002 a study was carried out to quantify the effect of shading on growth of poplar seedlings and population density and damage rate of two species of important poplar pests in Poplar Research Center of Safra-Basteh in Astane-Ashrafieh in Guilan province. Cuttings of the clone P. deltoides 69.55 were planted in this station in 9 rows (treatments) spaced differently from the adjacent shading trees, which were located in southern edge of the examining plot. There were 9 space intervals as treatment including 11, 12.6, 14.2, 15.8, 17.4, 19, 20.6, 22.2 and 23.8 meters apart from the shading trees. In the end of each year, heights of the seedlings and diameter of the stocks were measured and recorded. Population density of poplar mottled weevil, Clorophanus votuptificus and poplar defoliator wasp, Staurenematus compressicornis (important pests of poplar in this province) were counted weekly and were recorded for each treatment and replicates separately. Analysis of the data using MSTAT-C software showed that there is a significant difference between the treatments in terms of diametric growth and height. The more the distance of rows from shading trees, the more was their diameter and height. The treatments were in terms of the number of weevils significantly different (a=1%), so that the highest density of the weevil was on the treatments that were more in shade and the least number of weevils were recorded on the treatments 8 and 9 which had the most distant from shading trees. The behavior and reaction of the poplar defoliator wasp was completely different in terms of the population density of the defoliator wasp. There was a positive high correlation between height and diameter of the seedlings (r2=0.99) and a negative significant correlation was proved between the seedling heights with number of the weevils (r2=0.90). Correlation of the seedling heights with the number of the defoliator wasp was positive and significant (r2=0.73).

In order to investigate the relationship among mistletoe (Viscum album) infection intensity with some parameters, such as host species, DBH, height and location of host trees in Nour Forest Park, the number of 30 circular plots with an area of 1000 m2 were selected and sampled in regions had an aggregation of infected trees. In each plot, diameter at breast height, number of mistletoe’s clumps per each tree and trees location (in two conditions, adjacent to gap and inside of stand) and either  host species for all infected to mistletoe individuals were recorded. The results revealed that mistletoe abundance and infection intensity in Iron Wood trees were more than the other species in the study area. Furthermore, infection intensity to mistletoe in Iron trees had a direct significant relation with DBH and locating at edge of forest stand, but there was no relation with trees’ height as well. Totally, trees located at the edge of gap or adjacent to roads were more either in abundance or infection intensity than interior trees. This result shows that opening stand due to intense harvesting and also forest destruction can increase the potential of infection to mistletoes in each region.

Regional forest management and executing the related plans are directly associated with quality and quantity of planning and forest road network construction to access all forest areas. Construction of forest road is the most important manipulation occurred in the nature by human. Most of damages by forest roads construction are directly related to soil properties forming bed road. The recognition of these properties has a critical role in choosing the ground as one of the materials. In study area more than 18 kilometers of roads have been planned that should be accomplished by the end of rotation. The objective of this study was to evaluate mechanical properties of soil in order to use them in road construction and maintenance stages. Therefore 24 soil samples were selected using land unit map. With regard to result of pretests 13 zones with similar properties were divided. According to soil zonation map, 13 samples were taken using GPS and experiments were carried out in geotechnic lab. Classification of the soils carried out using the above experiments according to USCS method. Results show only two samples of all samples (16%) are coarse soil (SM, GM) and the others (81%) are fine soil (CH, CL, ML). 61% of fine soil have clay fine soil. Hence, in the parts of the road which have Liquidity Index more than one soils have to be drained before road construction and the parts that soils have high Plasticity Index have to stabilize Bed road with lime or using Geotextile for that do. For decreasing costs of road construction and maintenance. Routes have to across from areas that are stable. Reaching to this aim needs to survey soil mechanic properties map.

Chemical resistance of natural fiber (wood flour- rice hulls- kenaf fiber and newsprint)- high density polyethylene composite was studied in terms of their weight loss after seven days immersion in different chemicals. Composite containing 25% and 50% of varios natural fiber and high density polyethylene were prepared and immersed in NaOH(10%), NaClO(13%), HCl(10%), H2O2(3%), soap solution(1%) and acetone. Results indicated that H2O2, soap solution and acetone had very negligible effects on all composites. On the other hand, the effects of NaClO and HCl were found to be statistically significant. Different fibers exhibited different behaviors regarding their chemical resistance. Generally it was concluded that NaClO and HCl had the highest impact on natural fiber- high density polyethylene composites.

Deinking is important and detrimental for newspaper recycling and utilization. Since chemicals applied in deinking influences the removal of ink attached to fibers, the influence of two chemicals is investigated. Keyhan newspaper was deinked by oxidative deinking and bleaching process using three levels (1, 2, 3% based on oven dry weight of the paper) of sodium hydroxide and three levels (1, 2, 3% based on oven dry weight of the paper) of hydrogen peroxide. Optical properties of deinked pulp including brightness, yellowness and opacity of handsheets were measured. Results show that applying 2% NaOH and 2% H2O2 produces the highest brightness of deinked pulp at 61% ISO. Higher application of NaOH increases the yellowness of the deinked pulp. The highest yellowness was obtained at the highest dosage of NaOH and the lowest dosage of H2O2. However the opacity of the pulp produced from undeinked pulp was superior to deinked pulps.

The anisotropic and mechanical properties of newsprint paper made in Iran were studied in this research. Tear and tensile strengths, modulus of elasticity and breaking length of newsprint were determined at different angles to machine direction (MD) and at an interval angle of 15o (15, 30, 45, 60, 75) and cross machine direction (CD). The results show that modulus of elasticity, tensile strengths and breaking length of newsprint paper are the highest in machine direction, decreasing with increase of angle and reach the lowest (half) in cross machine direction. There is no significant difference between mentioned properties from 60o to CD. Tear strength of newsprint paper was the lowest values in machine direction, increasing with increase of angle and reach highest (half) at of and then decreases up to CD.

This research was conducted to investigate the effect of acetylation on the heat transfer of pressing plate to the core of wood particles cake during hot pressing and mechanical properties in particleboard made of acetylated particles from Fagus orientalis. After 12 hours soaking in acetic anhydride, in order to achieving three weight gains, 5, 9 and 16%, particles were heated in oven at 120oc for 30, 90 & 240 minutes, respectively. During pressing operation of particles, heat transfer was measured by thermocouple wires connected to thermometer. Results showed that by increasing the wooden paricles acetylation severity, heat transfer decreases. Also, by increasing acetylation percent, mechanical properties decrease.

The chlorine dioxide delignification efficiency of softwood karft pulp in the laboratory liquor displacement reactor (fixed bed reactor) was investigated and compared with conventional batch reactor. The comparison of two reactors was made based on the effective efficiency and overall efficiency of chlorine dioxide. Effective efficiency corresponds to the oxidizing capacity of chlorine dioxide which consumed by organic materials. Comparison of two reactors based on the effective efficiency showed that the selectivity of delignification significantly enhanced in the displacement reactor in which the primary reaction products are eliminated from reaction zone by displacing flow. On the other hand, the formation of high amounts of chlorate in the reaction zone of displacement reactor reduces the overall efficiency of chlorine dioxide delignification stage. Thus, in spite of significant decrease in useless secondary reactions, this type of reactor would not be cost effective in the industrial scale.

More than 27 sheep breeds graze on Iran's rangelands. For estimation of grazing capacity in each region it is necessary to determine animal requirement based on forage quality and animal unit weight of dominant sheep breed. In present study animal unit weight of Sangsary breed was investigated. Two herds were selected. Fourty head animals including 15 three and 15 four years' old ewes, 5 three and 5 four years old rams were weighed in lowlands. Weight of animal unit was 36.98 kg and animal unit equivalent for rams, 6 and 3 month old lambs obtained 1.31, 0.64, 0.42 respectively. Two season winter and summer, sex of animals (ewes and rams) and two herds were significantly differed (p<0.05). For determination of forage quality 5 samples that each was made from 5 individual plants collected. Crude protein, acid detergent fiber, dry matter digestibility and metabolisable energy were estimated for 6 species from highland and 12 species from lowlands. According Tukey test forage quality significantly differed between species (p<0.05). This showes that animal requirement should be determined based on forage quality of available forage to animals. Requirement of animal grazing on rangeland is more than house keeping animals. So in this research considering environmental conditions and distances that animal had to walk everyday %50 was added to animal requirement calculated using either NRC tables or MAFF equation. The result showed that animal requirement in highland and lowland based on NRC tables were 1.00 and 1,04 kg and according to MAFF eqution were  0.90 and 0.92 kg dry matter respectively.

There are large areas in arid regions having low rainfall affected by land degradation caused due to change in environmental condition and anthropogenic activities (e. g. agricultural and mis-use of the land). Consequently these fertile lands were changed in to degraded and bare lands. The goal of this study is the comparison of EC and SAR changes in agricultural and range lands. In many parts of arid and semi-arid regions of Iran agricultural activities such as unwise management of the land as well as inappropriate irrigation systems has seriously led to salinity and soil degradation. Then wise management of soil and water resources is inevitable to avoid consequence degradation. For this purpose different agricultural treatments were selected to compare SAR, EC with rangelands of Khormouj plain (Dashti county) of Boushehr province in two depths (0-30 cm) and (30-60cm). The results showed that there is significant difference between the measured factors both in top and sub soil. Comparison of means using Duncan test indicated that the highest amount of EC and SAR in both layers occurs in wheat cultivated lands; therefore this crop has resulted the highest degradation. Also the most favorable treatment in the study region is vegetable cultivation.

 The current research has been carried out with the aim to integrate vegetation index and rainfall data in a Geographic Information System (GIS) for identification of extremely vulnerable areas to drought in Iran. Limited amount of rainfall and climatic changes are caused occurrence of drought in the period ending 2003. Since the vegetation cover is directly linked with water availability. So, any decrease in vegetation cover can be alarmed as an indicator. Monthly rainfall data of about 719 rainfall stations were compared with the long term mean monthly rainfall data, within the five years (1996-2001), in order to find out the deviations from normal condition. The result of this division then converted to drought duration map by summing up the relevant ratios for each station. On the other hand NDVI images of each year were prepared, using NOAA-AVHRR images. Then maximum NDVI values were obtained among of these images as well. The maximum NDVI values of each year then compared with the maximum NDVI values of the reference year. Beginning year of the period of study (1996-1997) is taken as reference year. Result of this comparison led to production of vegetation cover changes map. This map is classified by making use of criteria stated by Jensen, 1987.  Areas faced to simultaneous decrease on vegetation cover and persistence of severe drought for more than 6 month per a year, were mapped as extremely drought zones. By cross operation applied on extreme drought zones map and land-cover map, land covers that are fallen in those zones were determined. Among of vegetation covers, sparse forests and rangelands are highly affected by extreme droughts and in the contrary damage to dense forests and irrigated lands were not severe.

A karyological study of six species: Trifolium campestre, T. dasyurum, , T. grandiflorum, , T. lappaceum, , T.  resupinatum, and T. repens  is presented.We used Video Analysis system for each species with Micromeasure software. Some features of chromosome such as SA, LA, TL, AR and CI were determined. For assignment of evolutionary situation of all species, except T.  repens that was tetraploid others were diploid and we found the two basic number in the genus: x=7,8. we determine karyotype symmetric parameters such as A1, A2, %TF and DRL. The data for all traits on each species were analyzed as RCD experiment and the results showed all species had significant difference for all traits at %1. This results were expressed variation chromosomes  in all  species. Using Stebbins method karyotipical characters were identified and it was shown that all of species are in 1A class.. Finally the 6 species were grouped in to 3 cluster.

It is important to select appropriate sampling techniques that provide an unbiased and accurate estimate of density in sparse and dense shrub populations with different dispersion patterns of plants. Methods of measuring density were compared on the basis of accuracy and sample size. Sampling was conducted on three shrubland stands in Yazd Nodushan. A (50*100-m) area was selected for sampling within each stand. Estimates of density were obtained from different methods and compared with actual density at 1 and 5% probability levels in a randomized complete design and Duncan’s test. The methods include: quadrat, indirect frequency, closest individual, nearest neighbor, random pairs, point center quarter, wandering quarter, wandering angle, Byth T square, Diggle’s distance point, six sector angle, Pollard's order, angle order, indirect cover and maximum diameter of plant. Degree of spatial patterning of plants was determined by indices of dispersion. The Byth T square and the second closest individual methods provided reliable estimates of density in sparse shrublands with cover £5% and a slightly clumped pattern, The fourth and third closest individual methods provided unbiased estimates of density in shrublands with cover between 5 to 10% and a random distribution. The closest individual and the Diggle's distance point methods provided reliable estimates in dense shrublands with cover ³10% and a slight tendency toward uniformity. The random pairs method provided reliable results in dense shrublands with cover ³10% and a strongly uniform distribution. Largest and smallest sample size were related to wandering quarter and angle order methods respectively compared to the other distance methods while quadrat method required the largest sample size.

Germination of different Atriplex species seeds needs especial treatments to have acceptable germination. In this study were tested different treatments on two Atriplex species seeds. Laboratory experiments were conducted to evaluate the effect of chemical scarification using 90% sulfuric acid for 10, 20, 30, and 60 minutes; mechanical scarification using debracted and debracted with testa pierced of seeds; stratification for 1, 2, 3, and 4 weeks at 6oC; and leaching for 1, 2, 3, and 4 days on seed germination of Atriplex canescens and  A. halimus . Effective methods for breaking dormancy of A. canescens seeds were scarification by 90% sulfuric acid for 30 min, and debracted of seed. In A. canescens maximum rate of germination was observed using 90% sulfuric acid for 30 minutes. In A. halimus, scarification with 90% sulfuric acid for 10, 20, 30 and 60 min were not effective for breaking seed dormancy because of damaged on embryos. In contrast, maximum seed germination and rate of germination were observed in mechanical scarification by debracted. In  A. canescens  and   A. halimus  leaching of the seeds for 1, 2, 3, and 4 days had the little effect on seed germination and rate of  germination.