نشریه علوم و فنون منابع طبیعی
سال سوم شماره 1 (بهار 1387)

The Alder, as the fourth important and industrial species of the north forests of Iran, consists of approximately 9% of the total volume of this forest in the west of Mazandaran. In order to recognize the forest stands, some quantitative characteristics of pure and natural stands of Alnus Subcordata (C.A.M), which is one of the precious and quick growth species of Caspian forests in the west region of Mazandaran (ranging from Nowshahr to Ramsar), were studied. The selected areas under the study were in 9 aquiferous areas and consisted of 43 parts of pure and evenly aged stands of Alder in an area of 0.5 to 2 hectares based on the age of the stand. The diameter at breast, height, and number of Alders in the hectare of natural stands of Alnus Subcordate were quantitatively studied. The results of the study showed that the existing number of Alders in the hectare of natural stands was very large in the initial ages, but it gradually decreased by increasing the age of stands. In this study, it was specified that more than 90 percents of reduction in the entire number of bases occurred when the stands reached to the diameter layers of 30 Cm, and this issue necessitated the premature breeding interferences in these stands. The study of diametrical and height growth of this species also indicated that the average diametrical growth of these stands was more than 1 cm per year, and the average height growth decreased from 1.7 meters per year in the adolescent ages of stands (until the age of 5) to 0.2 meter in the old ages (about the age of 50).

Sisangan forest park in an area of 570 hectares is located in about 35 kilometers to the East of Nowshahr, and it was introduced as a forest reserve in 1965. The Buxus Hyrcanas are the main types of trees, which considerably cover the whole area of the park and along with Carpinus Betulus, Parrotia Persica, and Quercus Castaneafolia comprise the major trees of the area. In order to gather more detailed data about the growth characteristics and the existing vegetative compositions, floristic studies were conducted by sampling from an area of 40 hectares run under the management of tourism. A total of 73 species from 65 genera and 39 families were identified from which the Asteraceae, Rosaceae, Lamiaceae, and Poaceae were the most important families which constitute the most prevalent species in the whole park. The Hemicryptophyte and Phanerophyte life froms were the most important ones in the park. The results of chorological studies showed that the chorotypes from some areas such as Euro-Sibria, Mediteranean, Euro Sibria, Iran Turanian, and also Hyrcanian were the most important phytochorions which make up the chorological structures of Sisangan forest park.

In the today's world, along with the development of globalization and increasing competition in the production and selling of different products, producers succeed to have a better turn over. One of the methods of surveying the operations of a mill is to estimate and measure its productivity which deals with the institute use of the production factors. In this study, the total factor productivity (TFP) and partial productivity of the Nekachoub plywood mill in a period of seven years, from 1375 to 1381, were determined by the index, and estimation methods and their process of changes. Then the relationship between the total factor productivity (as the most important estimated productivity) and the partial productivity and production factors were analyzed by the correlation coefficient and regression tests in order to determine the effective factors on the total factor productivity of this mill and specify the causes of reduction and increase of its total productivity index. The total productivity in 1375 with the value of about 1.49 was the maximum, and in 1377 with the value of about 0.53 was the minimum. In addition, the effective factors on the total factor productivity of this mill were the log productivity, output value, value added, and the labourer's productivity respectively.

This study aimed at investigating the effects of the age and height of trees on the chemical components of Eucalyptus Camaldulensis wood. For this aim, five normal Eucalyptus trees were randomly cut down from the research forest of Dr. Bahramneya, located in Shastkolateh of Gorgan. From each tree four disks from the breast height of 25%, 50% and 75% of tree's trunk were selected. The specimens were taken from the pith to the bark and from the bottom to the top of tree trunk to determine and measure the chemical components such as Cellulose, Lignin, Extractives soluble in alchoal-acetone and ash according to TAPPI standard. Then the data were statistically analysed. The results indicated that Cellulose content increased from the pith to the bark and decreased from the bottom to the top as the trees grew older. Also the Lignin content decreased from the pith to the bark and increased from the bottom to the top of tree trunk. The extractives soluble in alchoal-acetone decreased by the increase of the age and height of trees. The pattern of ash changes also followed the pattern of extractives in three axes from the pith towards the bark. In general, it can be concluded that the effects of the age of Eucalyptus Camaldulensis plant on the chemical components of its wood is greater than the effect of its height.

In this research, some chips pile of kiwi residues in the west of Mazandaran (Tonkabon region) were randomly chosen and NSSC pulps were prepared at the yield of 75% in 105 minutes, using the cooking conditions of MWPI of Mazandaran. Fluting papers were prepared from the Kiwi and Mill NSSC pulps of Mazandaran (control sample), first in a separate and then in mixed way. In order to improve the durability of handsheets, 5-10% of imported long -fiber were added to them. Then the optical and mechanical properties of handsheets were measured and compared according to the standardized tests. The results showed that the greatest strength to the burst, breaking length, tensile, RCT, porosity and opacity was in the handsheets obtained from the kiwi NSSC pulp% of imported long-fiber and the lowest strength was in the handsheets produced from the kiwi NSSC pulp. The results also indicated that the highest resistance to tear and brightness was in NSSC MWPI Mill, and the highest CMT and water absorption were in papers obtained from Kiwi NSSC. The results also pointed out that the above-mentioned strengths can be improved by adding 10% of imported long-fiber to the kiwi NSSC pulp. So the Kiwi NSSC Pulp % of imported long-fiber can replace some of the NSSC pulp of MWPI Mill, but it is not possible for the pure Kiwi NSSC pulp.

The forestal-mountainous region of Asas in an area of about 3001 hectares is located in the protected district of Savadkooh in an altitude of 700 to 1911 meters above the free sea level. A survey of the flora of the region showed that there were 177 species of plants, 67 families, and 138 genera. The Rosaceae with 6.74%, Lamiaceae and Asteraceae with 5.6%, Apiaceae and Fabaceae with 5%, and Poaceae with 4.49% were the most important families of this region. The life forms were surveyed by using the Raunkiaer method, and it indicated that the most frequent life forms belonged to Hemicryptophytes with 78 species (44%). This high percentage demonstrated that the region had cold and mountainous climate. The life forms of Chamaephytes with 18.6%, Phanaerophytes with 14.6%, Therophytes with 11.8%, Cryptophytes with 9.6%, and Epiphytes with 1% were the second important ones. The geographical distribution of plants, based on the Zohary and Takhtajan method, revealed that 62% of species belonged to the Euro-Siberian area, and this high percentage of species in this ares indicated that this region belonged to the Euro-Siberian vegetative area. Other species, in addition to being in the Euro-Siberian area, were also observed in other areas. Among these, 10 species with 5.6% were exclusive to Iran.

In this paper, the effects of change in the height of vegetatives and the different growing periods on the type and amount of compositions of the essence oil of Artemisia Herba-Alba plants were comparatively studied. The aerial parts of plants were collected from different altitudes of Hassan-Abad valley in the north of Iran in three growing periods. The essence extraction was done by the hydro-distillation method. The analysis and identification of essence compositions were made with the GC/MS and GC instruments according to the retention indices. The essence oil yields varied from 62% to 1.16% . Among the 33 identified constituents, with 89 to 92% of essence, the major components consisted of 1 and -8 Cineole, B-Thujone, Borneol, Camphor, Camphene, Therpinolene, and Bornyl Acetate. There were significant differences between the extracted essence yields and also the component compositions of different samples. These differences showed that the ecological and phonological changes had different effects on the biosynthetic pathways of each of the component compositions of essence oil.

The belief in the medical properties of plants and herbs, which has gradually been acquired since the old times, has been important among several different societies. Rosemary is one of the medical herbs, the growth of which is common in many areas of Iran. In this study, samples of Rosemary were collected simultaneously at a specific hour during the daytime from two areas of Kandelus of Kojur and Nowshahr, and after the preparation and separation of the effective material of the plant in leaves and branches by ethanole and water solvent, the ratio of Hydroxycinamic was measured according to Rosmarinic acid by UV/Vis spectrophotometry in the wave length of 505 nm. The results of the study showed that the amount of Rosmarinic acid in Kandelus of Kojur is 1.5 times more than in Nowshahr. Meanwhile the amount of this material in the leaves is 3.5 times more than that of the branches. This significant difference is due to factors such as the type of soil, the amount of rain, the altitude, the light and the temperature.