Year:2003 | Volume:15 | Issue:3-4 (56-57 IN NATURAL RESOURCES)|Papers Count:12

Although snow cover extent represents a critical factor in predicting snowmelt runoff, sufficient spatial and temporal resolution is not achieved by field observations. On the other hand, satellite data are readily available and provide exceptional spatio-temporal characteristics needed for snow mapping. In particular, NOAA satellite with AVHRR sensor provides daily images 1.1 km spatial resolution, which may with be quite suitable for snow mapping in large basins. The snow cover area mapping based on satellite imagery has been mainly practiced using visual interpretation methods. Moreover the presence of cloud in the images creats an obstacle in snow area delineation. In this article, a two-stage technique relying on albedo of channel2 and brightness temperature of channel2 and 3 some feature reflectivity of in and these bands in NOAA AVHRR is proposed to classify snow, cloud and uncover land. While visual interpretation is not required in this technique, the image classification is performed using image enhancement and multi-spectral analysis. ILWIS GIS served as the data platform for imagery data manipulation and analysis. To examine the capability of the proposed technique, two of the available NOAA corresponding to Jan. 9 and Feb 24. 1997. respectively in areas of 105000 and 132000 km2 between (47, 05, 00-51, 27, 06) E longitude and (30, 30, 00-33, 28, 51) N were selected. The results conferred overall with those of visual interpretation in areas where snow, cloud, and ground could clearly be identified. Furthermore, the results of applying the proposed technique on a third image dated May N. 1998, was favorably compared with processing of the May 17, 1998 LANDSAT/TM images with 28.5 m ground resolution. On major limitation of the technique is the inability to recognize the snow under cloud cover.

Yew (Taxus baccata L.) is one of the five conifer speciess, which grows naturally in Gilan's forests. This species extends from 220 to 1400 meters above sea level and can grow in pure and mixed stands with beech, maple, alder and etc. The objective of this study is to evaluate the status of yew natural regeneration. Cluster sampling method was carried out on 20 hectars of yew forest, which was located between 1180 to 1400 meters above sea level. The obtained results showed that the yew seedling grows both with seed and sprout. The density of yew seedling was one seedling per 10 square meters. The number percentage of yew seedlings at 0-5 mm. Collar diameter (CD) class was the highest while at 10-15mm. CD class was the lowest. Abundance of yew sprouts on the forest, showed that the severe environmental conditions which prevent the yew seedling to developed. The results of seedling height showed that the except of 0-5 CD class, the height of seedlings from seed were higher than seedlings from sprout.

The aerial parts of Thymus pubescens were collected in 3 samples from Lar valley, in Tehran province. Essential oils isolated by steam distillation (45 minutes) from the plant material at two stages, before flowering (SF) and full flowering stage (FF). Yields of essential oils were 0.53% to 0.93% (at SF stage) and 1.23% to 2.03% (at FF stage). Then the oils were injected GC and GC/MS and their constituents were identified. At SF stage 26 compounds (98.0% to 99.3%) and at FF stage 32 compounds (97.7% to 98.5%) were characterized. Major constituents at SF stage were: carvacrol (52.6%-77.9%), thymol (2.7%-21.8%), A-terpinene (3.3%-7.4%), P-cymen (2.2%4.4%), and tkaryophyllene (1.7%-2/5%). Major constituents at FF stages were carvacrol (54.7%-69.2%). P-cymene (6.7%-9.7%), 18 cineol+limonene (1.7%-3.2%), methyl carvacrol (0.6%-6.6%) and borneol (1.7%-5.1%).

In the near past, oak forests of Yasuj were covered by countless trees and other plants, but at present, owing to increase in human population, excessive grazing by domestic animals, deforestation and excessive use of trees and plants, expansion of agricultural lands and construction etc. their appearance has completely been changed into ruined forests. With the exception of areas out of human of animal reach, in other areas the forest has been intensively damaged and one can only see solitary crooked trees and scattered groves. The present research is a situational analysis of forests of the region in the past and present and an assessment of the traces and manner of destruction and a comparison of the past and present destruction and encroachment by man and animals: Therefore, an assessment of increase in human and live - stock population in the area and its impact on the destruction of these forests has been undertaken during the last 34 years (during two periods of 14 and 20 years) through aerial photographs of Zagros montainous areas located in the north-west of Kohkiluye va Boyerahmad province (Pataveh region) during 1955, 1969 and 1989. An estimation and comparison of the percentage of different types of land areas along with estimation and comparison of the percentage of different types of forest areas with varying grades of density from the viewpoint of coverage percentage during the above time periods have explained, controlled and assessed. Meanwhile, a qualitative and quantitative assessment of the present situation of the forests of the region with the provision of a systematic statistical network, and a study of the socio - economic situation of scattered hamlets in the forests and of the ribal and rural farmers and of the way of benefiting from the forest has been undertaken through a questionnaire. In view of the photographs taken during different periods of time, the findings of the assessment of the past situation of the forest indicate that as a result of direct destruction of forest by man and live-stock. The forest areas are constantly decreasing and the areas of arable and agricultural land are increasing. In fact, this reduction has an upward trend, for in 1955 around 78.2 per cent of the area under study was covered by forest, which in 1969 and 1989 decreased to 74 and 60 cent per cent respectively. During the above time lapse, the land covered by dense forest has been changed into less dense forest. The findings of the assessment of the present situation of the forests of the area indicate that as a result of deforestation and excessive exploitation, the situation area indicates that as a gradually deteriorating. Most of the trees have a ramification of branches with crooked and non - industrial firewood trunks. The average number of trees per hectare is 91.2 with 30 to 50 per cent crest coverage and the height of trees is 6 to 12 meters with 7 to 60 cm. diameter. The diametrical dispersion of trees is mostly of the diametrical categories of 10 to 30 cm. On the margins of the villages, as a result of cutting and excessive exploitation, the forests have been intensively damaged and due to perennial grazing of animals and their presence in forest area, the regeneration process of trees has been reduced.

There are as much as 20 rivers and drains in watershed of Anzali logoon. These rivers carry alarge amount of wastewaters into lagoon. Because of trophic condition cause undesirable effects for biotic community of lagoon, therefore the major goals of this study is distinction of pollutant and non pollutant rivers and representation of management programs for rivers and lagoon. In this study is selected as much as 15 factors such as NH4+, NO2-, NO-3, (K T.P.O -34, O.PO-34, DO, Na+, K+, BOD5, COD, T.O.M and total and fecal coliform. The number of (F, stations for sampling were 21 rivers in lagoon watershed. This study carried out for 30 months between 1994 - 1996 and in the half of 1998. Measurement of samples was done in monthy intervals. At first for analysis of data determined correlation coefficients between factors and after classification in four clustering. From each clustering was selected one important factor based on f. trophic condition including, T.P.O4-3. T.O.M, DO, Total coliform. For determination of ranking, average in different rivers is used kruskal wallis tests. Ultimately the normalized euclidean model was used to compare the trophic condition in pollutant and non pollutant. The results showed that from total of twenty one rivers. 5 rivers were highly polluted (Pirbazar river was more pollutant than others) and 9 rivers were medium polluted and the other rivers were very lowly polluted.

Natural forests are one of the major element in sustainable development and they are valuable genetical reserve in world with increasing demand to wood, planting of rapid – growing species, identification of resistant stand against environmental stresses and multiplying of them, is necessary for supporting of this natural capital. Investigation has showed that enzymes are the most sensitive factor during environmental stresses. In this research, peroxidase has been used because of its sensitivity against cold. For investigating of early cold, sampling was done from 5 Eucalyptus viminalis individuals in Saravan region 0 and 3 individuals in Anbaran region. The individuals were on the same age and sampling was done in the middle of Mehr (october) and the begining of Day (Jan) samples were carried laboratory and traded in (-5), (-10), (-21) and (+4) degree centigrade (+4 = control). Result indicated responses of different individuals to different treatment were different resistant individuals against early cold showed more rapidly increasing of peroxidase activity and increasing of catodic isoenzymatice bands. In this research, the 5th individual of Saravan was the most resistant individual and the 3th individual. Spectrophotometer method and polyacrylamide gel electrophoresis (PAGE) was used for study of quantitative and qualitative alterations, respectively next research will be about late cold and asexual multiplying of elit individual.

A series of experiments was performed in a laboratory flume to determine the threshold of meandering and braiding of river patterns. For the 4, purpose, of modeling, an alluvial reach of Ghezol Ozan (a meandering river in central north of Iran) was selected and using reasonable values of  geometric, hydraulic and bed material properties of  this river, a physical model with horizontal scale of 1: 400 and vertical scale of 1:40 was constructed. After performing several laboratory tests it was found that discharge and slope were closely related to the threshold values of channel patterns. Also based on regression analysis of experimental, results a number of analytical relationships were obtained for determining the threshold of meandering and braiding patterns. The proposed relationships are between the channel longitudinal slope and discharge and between the non dimensional unit stream power (NUSP) and shields parameter. The later is a new and interesting relationship in river morphology. Several diagrams were made to show that under what initial" conditions the meandering and braiding patterns are established. The laboratory observations of this research have indicated that at very low NUSP, the 4.channel remains straight, but at NUSP of 5.5 to 6.5 a meandering channel is formed and as NUSP increases to 12-22 a braided channel is formed.

Estimating sediment yield in un-gauged sub-catchments of upstream is an important component in planning and designing of soil conservation and watershed treatment, river training, flood control and hydraulic structures. Generally a number of relations in a given area are derived using data from several gauged catchments. Regression analysis and application of erosion and sediment models using catchments characteristics are another efforts to establish the regional relations to estimate sediment yield in un-gauged catchments in the same region. In the present study, annual and monthly sediment yield, rainfall data and some catchments characteristics were considered in 15 sub-catchments in Dez and Karkheh river basins, located in Lorestan province. Factor and cluster analysis realized two hydrological homogenous regions in this area. Multivariable regressions between annually and/or monthly suspended sediment yield with climate and the entire area. This study shows that the results for homogenous regions are more reasonable than the entire area.

The consumption amount of Rubia tinctorum L. (Madder) root in dyeing the fiber depends on the age of the plant as well as the amount of dye substance exist inside plant, a study was performed in Estahban Research Station in the Fars province of Iran for 3 years. In the middle of March 1998 the seeds were cultivated. The dye substance inside the roots, alizarine, was extracted with the help of a mixture of ethylic alcohol and ether in 1999-2000, and 2001 years. The juice extracted in different years was compared to each other using the TLC, experiment, Rf comparisons, UV, and spectrophotometer apparatuses. A test was used to analyze the obtained data statistically. The results showed that the amount of dye substance was different year to year. The young roots from one year plants had more juice than the older ones. However, the total yield of the older plants was several times more than the young.

In this research, slope instability hazard zonation in Rudbar area in North- Central of Iran has been carried out. For this purpose, several thematic layers were prepared and integrated using fuzzy set theory. Landslide inventory map was prepared through aerial photo interpretation and field survey. Thematic layers including slope rate, lithology, distance from fault, land use, precipitation rate, and peak ground acceleration were recognized as effective factors in slope instability and were used as input layers for preparation of hazard zonation map. Sample units in analysis are unique terrains produced from crossing six above-mentioned layers. In hazard zonation, fuzzy multi attribute decision making based on two weighting methods (experimental and information theory) was considered. Hazard ranking was calculated with two triangular and trapezoid fuzzifier functions. The research indicates that the type of fuzzifier has minor affect on the results. In zonation based on experimental weighting, usage of fuzzy number significantly improves the results, and weighting based on information theory causes appropriate results compared with experimental weighting method.

In this research the gypsy flora of Robat - Sefid, Khorasan province, Iran has been studied. Altogether, 271 herbarium were collected. They are including in 23 families, 66 genera and 85 species. Density and coverage of different species in 100 random sample plots were counted and measured. Respectively 28 soil samples were analyzed. Depending to the amount of gypsum in the soil and occurance of the plants on different contents of gypsum, 3 categories were recognized for plants, i.e. obligatory (2 species), preferential (19 species) and non differential (64 species). Onobrychis amoena ssp. meshhedensis anc Lomatopodium staurophyllum are obligatory species. Chorotype of the species were determined as follows:Irano - Turanian = %75.3Irano - Turanian & Sahara - Sindian = %8.2Irano - Turanian & Meditteranian = %3.5Irano - Turanian & Europa - Sieberian = %2.4Polyregion = %8.4Hemicryptophyte = %52.9, Therophyte = %23.5, Chamephyte = % 15.3, Therophyte / Hemicryptophyte = %3.5, Hemicryptophyte / Chamephyte = %1.2, Phanerophyte / Chamephyte= %2.4.

Biotechnology developed various microorganisms which are useful for bioremediation processes. For the first time in Caspian sea, Iranian region, yeast degrading crude oil has been isolated and identified. Sea sampling has been implemented in summer and winter. Isolation and identification analysis resulted in isolation of 16 yeast degrading oil from Shafarood and Astara water and sediments. These organisms identified as:Candida maris, Candida scotii, Geotrichum sp., Candida maritima, Cryptococcus marinus, Candida aquatica, Metschnilkowia krissii, Candida austromarina, Sporobolomyces roseus, Rhodotorula minuta, Rhodotorula alpine Sterigmatomyces halophilus, Candida krissii, Cystofilobasidum infirmominiatum, Schwanniomyces occidentalis, Candida maritima. Further studies showed in sediments of Shafarood Anzali station in winter the dominated species was Rhodotorula alpina whereas Candida aquatica was dominated oil degrading yeast in same sediment in summer season.In Astara sediments in winter the best yeast degrader was Candida krissi, Candida maritima, Cystofilobasidium infirmominitum and Schanomyces occidentalis whereas Sporobolomyces roseus was the best yeast in summer. The results obtained from water in Astara station indicated that in summer species like Geotrichum sp., Candida maris, Cryptococcus marinus, Candida krissii, Candida maritima, Metschnikowia krissii were dominated and in winter Sterigmatomyces halophilus, Rhodotorula and Candida. In Shafarood Anzali water the best oil degrading yeast was Candida austromarina.