IRANIAN JOURNAL OF NATURAL RESOURCES
Year:2008 | Volume:61 | Issue:3|Papers Count:22

Over 40% of the northern hemisphere is covered with seasonal snow. Snow covered area is a huge water resource on most part of the world and mountainous areas. Snow-cover and its equivalent water, supplies 1/3 of the water requirements for farming and its land irrigation throughout the world. In most northern and alpine environments, snowmelt runoff is responsible for both the annual maximum instantaneous discharge and a major portion of the annual flow. The high albedo of snow coupled with its large areal extent makes it a strong influence on the Earth's radiation budget. Snow cover monitoring is necessary for climatologists. Therefore, continuous snow cover monitoring and survey of snow cover maps due to higher efficiency of snow cover in different studies is very necessary. The most efficient means of monitoring snow-cover extent is by remote monitoring from satellites. MODIS compared with other images like NOAA has better spatial resolution and more bands and is better for survey. In this research by MODIS data in Ghaleh-Shahrokh sub-basin, we prepared snow cover map. The results compared with real snow cover map and showed higher precision. Finally, these maps are used as basic maps in various cases such as estimation of snowmelt runoff.

The present study attempts to assess quantitatively the desertification process to develope a regional model in Fidoyeh- Garmosht plain in Fars province with area of 43000 ha as a case study. In this study, based on the MEDALUS method and according to the characteristics of child: area a regional model was developed using GIS. In the first step, all major factors affecting desertification were determined. These main six indicators (layers) included: soil, climate, erosion, plant cover, groundwater and management (for human activities). Then a number of sub-layers for each main layer affecting the quality of main layers were identified. To each sub-layer a number between "1 to 2" according to the MEDALUS method was denoted. These denoted numbers were considered as a weight for each sub-layer. GIS (ArcGIS 9) then was used to analyze data to prepare the main layer status maps using geometric mean for the sub layers and the main layers. Ultimately, the maps were combined and based on the geometric mean of the main layers, a desertification potential status map was developed. The results indicated that 12% of total study area classified as a very severe class, 81% is classified as a severe class and 7% of area classified as a moderate class of desertification. The results showed that plant cover and groundwater quality are the most important parameters that affecting desertification process in the Fidoyeh- Garmosht plain.

The analysis of spatial extension of drought is an important issue in drought risk management. The estimation of influenced region of drought in Isfahan province is the aim of this study. To do this, the annual rainfall data of 12 stations of the most important stations of Isfahan province were used in the period of 1973-2003. First, trend and homogeneity tests were applied and Isfahan station was detected to show a significant trend. Then, drought condition for each year was determined using four indices including PNPI, DPI, RAI and SPI. The results showed that drought covers 31, 37, 23 and 52% of entire province at each single year based on the above indices, respectively. The study also showed that, among different indices, only DPI has a significant relationship with longitude. This implies that drought intensity and frequency increase eastward. However, other indices did not show the same relationship. According to SPI, as the most important index, 50% of the entire province has been influenced by drought during 30 years period. This revealed the importance of launching a regional drought monitoring and management system to reduce drought disaster.

Shoor river watershed has the area of 17000 km2, 42% of the watershed is plain and the rest is pediment. In investigation of the effect of geological criterion on land degradation in geomorphological units, first a part of Shoor river watershed was selected on geological map in sucha way that different consolidated and unconsolidated geological materials which are effective on land degradation and desertification are included. After determination of the studied area, the maps of slope and land uses were prepared and overlaid and the map of homogeneous units was prepared. In this research, three indices consisting of erodibility, salinity and permeability of rock units were chosen, by field and laboratory analyses and finally their classified maps were prepared, they were then overlaid and zonation map of the area according to the three indices were presented. Due to the fact that the determination of desertification intensity or potential in homogeneous units by using mathematical or statistical equations is not possible, therefore, the concept of fuzzy logic was used for zonation that after determination of the weight or value of the factors, fuzzy algebraic sum, fuzzy algebraic product and fuzzy gamma were used. The results obtained from the comparison of maps prepared using different fuzzy operators with a control map and maximum and minimum measured desertification in the studied region, has shown that the most suitable fuzzy operator for desertification potential or intensity in the studied area is 0.8 gamma fuzzy function. Finally by overlaying the zonation map of desertification intensity with respect to geological criterion and the geological map, different geological units were characterized based on their desertification effect.

In this study the time series of annual maximum dry spells and the number annual dry spells of Isfahan province were analyzed in order to establish the existence of rainfall variability using Mann-Kendall test. The selected time series were first tested for homogeneity. Results indicated statistically homogeneity at 95% significant level. The results of trend analysis showed that only 2 stations have significant decreasing trend of the maximum annual dry spells at the significant level of 5%. The results also showed3 stations with increasing trend in the number of dry spells and 1 station with decreasing trend in the number of dry spells which are significant at 5% and 1% significant levels respectively.

The potential of ASTER images from the Marivan forests, dating June 2003, for forest density mapping in Zagros was investigated. The aerial photographs (scale of 1:20000) dated September, 2004 were used to generate a ground truth map. Images did not show any radiometric error. Geometric correction of images and photographs was implemented using Orthorectification method with RMSE less than one pixel. Different synthetic bands from rationing, principal component analysis and suitable vegetation indices were created to employ in further digital analysis, together with the original bands. The data were classified based on four classes using supervised method with the maximum likelihood, minimum distance to mean and fuzzy algorithms using synthetic and original bands. The highest overall accuracy and kappa coefficient equal to 65.5% and 48.7% were obtained with maximum likelihood algorithm. According to the primary results, the highest spectral similarity was observed between the 4th and the 5th classes. On the other hand, 5th class had a little extent in the study area. So, the 4th and 5th classes were merged. In three-class classification, the highest overall accuracy and kappa coefficient equal to 68.5% and 51.5% respectively, obtained with maximum likelihood algorithm. Spectral similarity between open density classes, lack of precise topographic maps and also shade effects on interpretation and analysis were the most important problems. Finally, it can be concluded that the resulted accuracy, using the data set, processing and analysis methods considering the restrictions, was relatively desired.

It is usual to see destructive effects in forest soil such as soil compaction, wheel and log tracks in forest utilization operations after using skidders. Soil weight moisture is one of the factors effective in soil destruction. The more this moisture is, the more the soil is destructed. Soil destruction and disturbance is the least if the soil weight moisture is in optimum. So in order to decrease the soil destruction it is necessary to determine a threshold. Using For-Pro software the soil moisture threshold is determined by entering soil and machine information. The destruction in soil with less moisture and more moisture than threshold is compared in this study. It is resulted that the rate of disturbance in dry soil is 0.72 cm. In each point each time the skidder passes and this rate is 1.37 cm for moist soil. Also it is concluded that the effect of skidders in dry soil is compaction and in moist soil, it is great disturbance in the soil horizons.

In north of Iran, the animal logging in Hyrcanian forest is a traditional method over past decades. Recently, with increasing environmental interest, concentration on environmentally sound timber extraction and small scale tree harvesting, the proportion of mule logging was increased in Caspian forest. The objective of this study is to develop a standard unified method of data collection to be used to improve the efficiency of mule logging operations and improve the quality of hauling cost and productivity information available for use in forest management plans and decisions. An environmentally sound timber extraction technique for small tree harvesting, particularly for thinning operations, were presented and introduced in this paper. The research was carried out in 213 compartment of Namkhaneh district, in Kheirood forest. Two types mule logging crews working in Kheirood during the study period were selected as the sample for this study: 1) Mules for lumber hauling in downhill, 2) Mules for lumber hauling in uphill. Time per turn for hauling of lumber in down and up slopes averaged 8 and 8.6 minutes, respectively. Regression models were developed for production-related elements with variance analysis using SPSS software. The hourly production of hauling with mule (m3/h) with delay time, for hauling of lumber in uphill and downhill were 1.00 & 1.2 m3/h, respectively and without delay time were 1.21 & 1.5 m3/h, respectively. The result showed that production of lumber in down slope was greater than production of lumber in uphill. In addition, mule rate or hourly cost of mule hauling system in productive mule hour was 57982 Rials/h. As a consequence, the changes of hauling costs showed that increasing hauling distances variable on lumber hauling caused to linear increase in cost.

Forest soil is one of the main components of forest ecosystems and effective factors in spatial dispersion of vegetation. The current research was carried out in Patom, Namkhaneh, Gorazbon and Chelir districts of Kheyroudkenar forest, Nowshar. After field inspection and identifying the individuals of Wych elm with D.B.H ³10 cm, their positions were recorded by GPS with reasonable accuracy. Soil sampling was followed from spatial pattern. For detecting the spatial pattern of the remaining individuals of Wych elm, mean square method was applied. The result of this method showed that the existing pattern of Wych elm is an intermediate one and its real pattern has been probably changed due to Dutch elm disease and illegal cutting. After determining the pattern and soil sampling, PCA method was used to test the soil variables. Altitude, aspect and slope constitute the grouping criteria in random and clumped patterns. In clumped pattern, soil texture, bulk density, moisture, N, P, K and organic matter were the most important factors, while in random pattern in addition to the mentioned factors, pH is also effective.

Influence of nursery soil amendment was studied on growth and survival of Cypress (Cupressus sempervirensvar. horizontalis) seedling in an afforestation area. For this purpose, at first Cypress seedlings (1+1) were grown at four soil treatments including 1) nursery non-amended soil (control),2) nursery non-amended soil and pure sand (1:1), 3) nursery non-amended soil, pure sand and organic matter (1:1:1), 4) nursery non-amended soil, pure sand and organic matter (1:1 :2). Then, the seedlings were transplanted into an afforeststion area located in a semi-arid region (Marzan-Abad, north of Iran with elevation of 300 m a.s.l.) and planted in holes with suitable depth. The research was set up as randomized complete blocks design with four replications. The results of first year revealed that seedlings grown in "nursery non-amended soil, pure sand and organic matter (1:1:2)" had greatest total height and crown length; however survival, collar diameter and crown diameter were not affected by soil treatments. In the second year, no significant differences were detected in total height, survival and crown diameter of seedlings treated on different soils, but contrary to first year, the seedlings grown in "non-amended soil, pure sand and organic matter (1:1:2)" obtained the greatest collar diameter. Based on the results of this research, nursery non-amended soil, pure sand and organic matter (1:1:2) can be suggested as suitable treatment in order to advance the establishment and growth of Cypress seedlings in the research site and the similar areas.

Between Birds Garden and Varzaneh town, a distance of approximately 140 km, eight stations were selected to sample and identify the macrobenthos of Zayandeh Rud, for a full year commencing fall 2002. Sampling was carried out twice at each season, using a Surber, an Ekman sampler and a PVC tube. The specimens were sorted out, counted and identified to the nearest genus, and some to a family level, using the appropriate identification keys. Identified specimens were classified into 19 genera, 17 families, 13 orders, and 5 classes. Amongst the 13 identified orders, Ephemeroptera and Trichoptera were the most diverse groups and were mostly distributed in Isfahan region and upstream. Oligochaeta with 3 orders and 4 families, and Diptera with 3 families and 2 genera were mostly distributed in east of Isfahan. At the same time, Lumbriculidae, Lumbricidae, and Tubificidae and the genus Chironomus were present in all the stations and throughout the year, though they showed a wide range of differences in density. In contrary, Glossiphoniidae and Baetis, Piscidium, Hydropsyche, Agrion, Valvata were present only in some stations and seasons. Statistical analysis of the data indicated that Shannon, Simpson, Margalef richness index wear significantly and negatively correlate with EC and substrate content of organic matter. The Shannon index was lower in mudy-sloughy stations, while Margalef richness index positively correlated with water pH. The differences in benthic population structure could be attributed to physical changes in the river substrate, chemical properties of the water and/or their life cycle or the interactions between them.

Air pollution is one of the main problems in metropolitan areas. Therefore, the prediction of air pollution can be regarded as one of the important issues of air quality research in urban areas. There are many methods for the prediction of air pollutant concentration. In recent years, there has been considerable progress in the development of neural network models for air quality prediction. In this paper, artificial neural network has been used for the prediction of CO concentration in Tabriz. Hourly correlation between the concentration of CO and metrological variables was calculated by multilayer perceptron for the months of December and January 2003. Multilayer perceptron performance was compared with traditional methods such as auto-regressive integrated moving average (ARIMA). The results indicated that there was a high non-linear correlation between CO concentration and metrological variables such as: speed and direction of wind; and relative humidity. The location of large industries in the west and southwest of Tabriz were found to be the most effective elements in air pollution. Blowing of winds from west and southwest directions, on the months of December and January have caused pollution are transferred to the inner parts of Tabriz.

Mismatch between the school furniture and body dimention of children is one of the important factors affecting the deformation of spinal column and causing low back pain. In addition, it can be a prefactor for mental disorders. Also, it causes bad-temper and bad-behaviour in students. Lack of normative anthropometric measurements of Iranian children, serving as a basis for furniture construction, could be the reason for this problem. The purpose of the present study is the optimization of ergonomic factors to design school furniture based on students anthropometric characteristics for increasing students' health. 2,000 students (M:1,000, F:1,000) in primary schools ranging 6-11 years old in Karaj city, from 4 education areas, were randomly chosen, 16 primary schools and 25 students from each class of every 16 schools on the basis of BSI5873 standard. They were then divided into 2 age groupes, 6-8 & 8-11, and the seated anthropometric characteristics like popliteal height, buttock-politeal length, and knee height were measured. Also the furniture dimonsions were measured to compare with the measured anthropometric items: Desk height, desk clearane, seat depths, and seat heights were measured. The data were analyzed with Minitab ver 15 & Statistica ver. 7 Softwares. The results showed, except knee clearance, none of school furniture measurements are in the range of pupils' body dimonsions. It was conculuded that the design and manufacturing of school furniture are done without any attention to anthropometric rules and in future it might put the health of the society at risk.

The increase in the volume of wood consumption on one hand, and the shortage of resources on the other hand, has made an urge for utilizing fast-growing trees. In this connection, special interest is focused on different poplar hybrids and clones due to their many outstanding characteristics. It has beenlong since Populus deltoids (69/55) and Populus x euroamericana (cv. I-214) have been under closeconsiderationas well as vast plantation in Iran due to their high yield, adaptation to different climates, and ease in tending techniques, protection, and utilization. Therefore, in the present study we evaluate and compare fiber characteristics of juvenile and mature woods of these two clones. Sample trees were taken from Safra-baste Poplar Research Station, located in Gillan province, Iran. Fiber characteristics were taken yearly for the first 6 years of growth, and then every three tree rings together for the rest 14 years of growth. Results show that the transition age of juvenile wood to mature wood inthese two clones takes place approximately when trees are 12 years old. Statistical analysis shows that there is no significant difference in fiber characteristics at %1 confidence level for different geographical directions in Populus x euroamericana; whereas significant difference was observed for lumen and wall thickness in Populus deltoides. Statistical analysis also shows that there is significant difference at %1 confidence level between fiber characteristics of these two clones. Based on the means and statistical analysis we can find out that fiber length, fiber diameter, lumen, and wall thickness in Populus x euroamericana (cv. I-214) are generally higher than Populus deltoides (69/55).

The ultrasonic wave velocity was used to detect decay extent and depth. An oak block (15x20x30 cm) with local decay was inspected in three main directions (longitudinal, radial and tangential). Ultrasonic wave velocities in three axis of decayed oak were incorporated into contour and color gradient plots along the wood profile for three direction inspections using Sigma Plot software. The specimen was dissected to compare the predicted internal condition to the actual internal condition. The results showed that the predicted internal condition by ultrasonic technique is in good agreement with the actual internal condition D. ecreasing of ultrasonic wave velocity depends on depth and different stages of decay.

Paper production lines have got many process variables and wide variety of operations. The overall objective in pulp and paper mills is to meet the specified quality and production targets while minimizing operation costs. Today in order to accurate, cheap and fast control of production lines, different kinds of models are being developed. Using real data of CMP tower, stock preparation, and paper machine wet-end variables of MWPI (Mazandaran Wood and Paper Industries) recorded during 2005 and part of 2006, four data set containing 72 process variables corresponding to the newsprint burst and tear strengths were prepared. The most influential variables and statistical predictive models for newsprint burst and tear strengths were generated using correlation and multiple regression. Several suitable models were developed to predict and control newsprint burst strength. The most influential variables to the burst strength were the amount of fibers remained on the 48mesh screens, stock pressure in the third group cleaners, output of second fan pump, save-all drainage rate, rush and drug ratio and head box slice opening degree. Process variables showed low correlation to the tear strength and few models were developed. Flow of retention aids, save-all drainage rate and clay ratio were the most effective variables to the newsprint tear strength.

In this research, Horn Beam chips were chosen randomly from chips pile at Mazandaran Pulp and Paper Mill and pulped by CMP process at the yield of 85%.Then, one portion of pulp was bleached by using hydrogen peroxide and DTPA as chelating agent and 60 gr/m2 handsheets were made from bleached and unbleached pulp. A number unbleached handsheets were acetylated by using acetic anhydride at 80°C for 30 and 60 minutes. The hand sheet was irradiated for zero, 10, 20, 30 and 40 hours for accelerated aging. The optical characteristics of the hand sheets were measured before and after optical aging. The results of this study showed that following bleaching and accetylation, absorption coefficient, K/S ratio, opacity, yellowness, greenness and post color (PC) number were decreased, and brightness was increased. Following aging up to 40 hours, all optical Properties (except brightness) were increased. These changes are more tangible up to 20 hours irradiation. Among the handsheets, acetylated handsheets, especially those acetylated for 60 minutes, have better brightness stability and less brightness reversion and therefore better resistance towards optical deterioration.

Determination of range grazing capacity is one of the most fundamental aspect of range management and understanding the effective factors on grazing capacity is an important issue. Grazing capacity is determined on forage production during the growth period. The objective of this study was investigation of relationships among canopy cover, foliage cover and basal cover with production. Three vegetative communities including 1-Grass-Shrubland, 2- Grassland and 3- Shrubland with 10 vegetation types were selected in Semirom, Isfahan province and Nadoshan and Nire in Yazd province. In each vegetation type 30 plots having 1.5x2 meter quadrats, were randomly established. After recording the species in each quadrat, canopy cover of palatable species was determined by using ruler. Basal cover and foliage cover were also measured using a point frame in qudrats. Grasses were clipped at height of 1cm above ground and current growth of shrubs was clipped for dry weight determination. Regression analysis was carried out between basal cover, foliage cover and canopy cover as independent variables and production as dependent variable for each species. According to the results, canopy cover of all species and foliage cover of most species had highly significant correlation with production (p<0.05 or p< 0.01). However no significant correlation was found between basal cover and production due to small number of point touches with this type of cover.