IRANIAN JOURNAL OF NATURAL RESOURCES
Year:2003 | Volume:55 | Issue:4|Papers Count:15

Because of major damages caused by mass movements on human and financial resources due to increased rate of erosion in Iran, this research intended to determine factors affecting mass movement for preventing and controlling purposes. To meet this aim, the effects of slope and aspect, as two major factors affecting mass movement, were studied in Taleghan watershed using GIS. After digitizing, overlaying, scoring, classifying and comparing of available data, the best and safest pathway between Dizan and Narian villages located on the watershed were then determined.It was attempted to determine the effects of each of the above-mentioned factors on mass movement exclusively on sulifloxion. However, the results showed that there is another factor playing the role of aspect factor. Finally, after studying other factors, it was found that active faults and over thrusts play more extensive roles on sulifloxion than aspect in mass movements. In addition, the results showed that the most vulnerable slopes for mass movements were classes III and V (i.e., 10-25% and 40-60% slopes, respectively), but for other slopes (outside these two classes), mass movement decreases.

Collection of flood in arid regions is done by several methods. One of them is traditionally used in Khorasan province named Bandsar. Collection of floods in the reservoirs of Bandsar has such benefits as deposition of the sediment, increase of soil moisture, and recharging of ground water. In this study, the effects of flood collection on soil physical and chemical properties were determined for an area in Birjand town, south of Khorasan province. It was found that collection of floods in Bandsar affected the soil physical and chemical properties. It should be noted that these effects were more obvious for physical characteristics since it improved soil condition and structure. On the other hand, it chemically increased mineral and organic matter in soil; however, this effect was not sensible. Generally, it can be mentioned that flood collection in the Bandsar was important both for ground water recharging and cropping. Finally, paying enough attention to this aspect of flood mitigation can solve many problems related to drought in arid area.

In recent years, flood control projects have been widely applied throughout the country. An important aspect in these projects is a great volume of labor and therefore trends cost involved. Prioritizing the sub-watersheds is practically perfonned traditionally. The goal of this research is to propose a mathematical method to prioritize and select a better choice. Overall, in these issues, we can us~ different multicriteria decision making (MCDM) method. Most MCDM methods automatically line up the selections and provide the result without incorporating the decision-maker. Among those, the utility additive (UTA) method with greater flexibility was considered in this study since it gives a greater importance to decision maker. The UTA method constantly asks for selection of the decisionmaker through some steps using piecewise linear programming. In this study, 49 sub-watersheds of the Kan River in Northwest oXTehran were evaluated according to 50 years return period of flood, lag time, and fatal-cost damage. The results show that despite the multi-component goal, the K3 (Keshar) sub-basin is number one with regard to practicality. This method can effectively be used in these projects to reduce the high cost in low priority sub-basin.

In order to find out the relationship between beech nut production and properties of Edafic, physiographic, and leaf element nutrient factors in the pure beech stand, 30 beech trees were selected from 40 to 130cm. This study was conducted at the Kheyroud-kenar research forest where beech nuts were collected from all four geographical directions around each tree. Sampling was performed on the basis of cluster sampling method where plots of 1m wide were used, the length of each plot being the same as the radius of tree crown. Total beech nut of each tree was determined and divided into five categories: 1) empty, 2) undamaged seed, 3) consumed by mouse (Glis Glis), 4) consumed by other animals, and 5) consumed by insects.The results of the classification showed that only one percent of seeds were undamaged, but 99% percent were damaged seriously by biotic and abiotic factors. Data analysis indicated that there were significant relationships between total production with tree diameter and height, as well as canopy height and diameter. The data matrix from soil nutrient elementsand leaves nutrient agents were used to execute a PCA (principal component analysis) in order to reduce the number of independent environmental variables in data set by finding their combination lines. Trees with the highest fruitification had a significant correlation with depth of soil, nutrient elements in soil and leaves (especially B element in both), and soil moisture. The trees with lowest fruitification were correlated with steep slopes, dry sites, nutrient element deficiency, and shallow soil.

The influence of some environmental factors on qualitative behaviour of beechsaplings (Fagus sylvatica L.) was studied in various beech forest associations growing in submountane region (500-800 m.a.s.l) of Switzerland. The experimental plots were established in regeneration gaps resulting from irregular shelterwood (Femelschlag) system. Within each gap, 15 sample plots were selected systematically. To determine light intensity, one hemispherical photograph was taken from each sample plot.The most important results are as following:- The quality and branching system of beech Saplings were strongly correlated with light, polycyclism, length of the uppermost internode, browsing (game) damage and slopeaspect.- Relative light intensity and slope aspect had significant effect on forming of distal terminal buds, which led to an increase in the proportion of silvicultural undesirable saplings.- Excess light resulted in a smaller length of the uppermost internode which was also smaller in the lammas shoot than in the regular shoot.- The smaller was the length of the lammas shoots, the higher was the proportion of forked and broom shaped saplings.

This study was carried out in order to compare the establishment and resistance to drought in semi-arid sites of 7 needle leaved and broad leaved tree species (Pinus brutia, Cupressus arizonica, Cupressus sempervirens var. horizontalis, Tetraclinis articulata, Robinia pseudacacia, Ailanthus altissima, Celtis australis) in Tajan river basins (Pysuma region) for a period starting from 1990. The form of experiment was completely randomized blocks design with 3 replications and 7 treatments. Survival, mean collar diameter, mean height and quality parameters were determined and analyzed after 5 years.The analysis of variance showed that differences between treatments were significant; thus it can be concluded that Cupressus arizonica is the best, Celtis australis and Pinus brutia are good, Robinia pesudacacia, Ailanthus altissima, and Cupressus sempervirens var. horizontalis are in the middle stage, and Tetraclinis articulata is the worst.

In order to know about the structure of natural stand that have considerable ability of auto-regeneration and auto-regulation, it is needed to access the knowledge about the evolution process of forest ecosystem before planning for harvesting. This knowledge could be useful to determine a suitable pattern for the selection of silvicultural method. To obtain the structure condition and evolution process in this study, ten plots of one hectare area each (with grid or dimension of 100m×100m) were selected in Gorazbon district (Kheyroud-kenar Forest, Noushahr) and stand characteristics including number, D.B.H, height per hectare were measured in addition to crown diameter and height in strips with grid 10m×100m in each plot. The results illustrated that beech species was dominant with respect to height. Regarding high longevity of beech, discontinuous crown of trees, this stand is old with two or three storied and it is far from the optimal, showing the beginning of regeneration phase and passing destruction while overlaping aggradations (increasing stage) and desection stage.

Determination of effective criteria in decision making to find optimum location for industrial units is very important in any country. To identify effective criteria for location selection of plywood and veneer units in Iran, four units were evaluated in provinces of Gilan, Mazandaran, Ghazvinand Hamadan. These criteria were divided into five major groups: economical, materials, infrastructure, technical, and instructions as well as 25 sub-criteria. The priority rates of these criteria and sub-criteriaobtained from AHP method and Expert Choice Software. The results indicated that among 25 effective sub-criteria in location selection of the units, the subcriteria of purchasing raw material, reliability of supply, quality of raw material, and granted facilities had the highest priorities.

Data collected on air quality monitoring programs are unusable in the raw form that is collected. It is therefore desirable to summarize the data in ways that make them relatively easy to interpret and use them for regulatory purposes. In this survey, pollution standard index (PSI) was calculated for five major pollutants (CO, O3, NOx, SO2, PM10) in Tehran and Isfahan in 1378. The data were classified on the basis of standard air quality chart to levels of: good, moderate, unhealthful for sensitive groups, unhealthful, very unhealthful and hazardous. After collecting data, analysis was done using Excel, Word and SAS and the results were presented in tables and charts.Results indicated that Khordad, Shahrivar, Aban and Bahman in Tehran and Khordad in Isfahan were the most contaminated months. As indicated, in Tehran for 90 percent of days in 1378the index was greater than the standard level; for 50 percent, the air quality was very unhealthful and for 4 percent, hazardous. In Isfahan, for 9 percent of days, the index was greater than the standard level; and for 4 percent, the air quality was very unhealthful. When PSI is more than standard, for 96 percent of days in Tehran and 70 percent in Isfahan, the responsible pollutant was considered to be Carbon Monoxide the main source of which in cities are cars and vehicles. Thus, management efforts for air pollution reduction should be focused on transportation control.

Animalunit requirement is calculated 1.5-2Kg dry forage for each day in grazing capacity estimation, but forage quality differs from one plant to another, region to region, and in different growth periods. Thus, calculation of animal unit requirement based on forage quality will be a more reliable indicator than using 1.5-2kg dry mater when estimating grazing capacity. Animal unit body weight of the Lori- Bakhtiari sheep was determined to be about 50 kg. Animal unit requirement in maintenance condition and grazing in rangelands (0.6 times of keeping in a stable) was extracted from NRC tables based on crude protein (152 gr.), metabolic energy (13.4 mJ) and 2 percent body weight forage (1.6 kg). Forage quality was measured for nine vegetation types in the region. With consideration of animal requirement and vegetation composition of each vegetation type, forage quantity that supplied metabolic energy, crude protein, and 2 percent body weight dry mater was calculated in maintenance condition and grazing in rangelands. Using completely randomized design with 3 treatments and 9 replicates for each treatment, statistical comparison of forage quality that provided animal requirement showed significant differences (P<0.01).These results showed the necessity of calculating animal unit requirement based on forage quality in different regions and conditions.

The effects of sheep trampling on organic matter, nitrogen, phosphorus and potasium of soil in a Bromus tomntellus pasture at the end of grazing season were studied in 2000. The place of study located on a high plain with elevation of 1960 m from sea levelwhich was surrounded by mountains in 70 km northeast of Tehran (Homand Abesard Research Station).Two treatments of continuous and rotation systems and four treatments of no grazing, light, medium and heavy grazing intensities were applied. Grazers were Sangesary sheep which remained on the pasture throughout the experiment period. The pasture was divided into two parts according to the grazing systems and each of them divided into four patches due to grzing intensities. In each treatment 12 hours and then the elements of N, P, K and organic matter measured. The measured parameters were compared by t-test method for all treatments. The results showed that the grazing but the differences were not significant. So the amount of accumulated organic matter decreased while the grazing intensity increased. Also there were not differences between grazing systems statistically (P=0.24) but the amount of organic matter in the continuous grazing system was more than rotation one. Soil nitrogen decreased a little while the grazing intensity increased. The reduction of N in rotation system was more than continuous one. But there was not meaningful difference between them (P=0.51). Totally, the grazing systems had a considerable effects on the meaning full (P=0.07).The soil phosphorus in continuous system was more than no rotation system in comparison with control (P=0.04).The soil potasium was less than but the rotation system reduced it more than continuous one (P=0.14).

Classification of the rangelands condition used by range managers in Iran is based on climax theory in which the condition is assessed by the deviation from the climax. Due to the fact that in Iranian rangeland ecosystems the ecological studies which show the degree of climax based on the floristic composition, was not carried out, the use of the above method has been encountered with difficulties scientifically and experimentally. In this approach, it was tried to propose a method called Pasture Value (PV), in which the floristic composition, quantitative analysis of vegetation and the use of palatability index were used for determination of the rangeland condition and capacity based on Iranian ecological situations.Primarily, results showed that the Pasture Value variations for different classes of the rangelands in northern Iran could have the following trend for a 120 day grazing period per year and can be used for classification accordingly:- For PV>51, the rangeland is excellent, with grazing capacity of 1.5-2 animal unit per hectare.- For 39<PV<51, the rangeland is good, with grazing capacity of 1 animal unit per hectare.- For 26<PV<39, the rangeland is medium, with grazing capacity of 0.75 animal unit per hectare.- For 13<PV<26, the rangeland is poor, with grazing capacity of 0.5 animal unit per hectare.- For 0<PV<13, the rangeland is very poor, with grazing capacity of 0.25 animal unit per hectare.The grazing capacity is 2 percent of Pasture Value in one grazing period per hectare for one animal unit.