Journal of Forest and Wood Products
Year:2009 | Volume:62 | Issue:2|Papers Count:9

Mechanical properties of neutral sulfite semi-chemical (NSSC) pulps produced from rapeseed residues were investigated. Preliminary pulps were prepared applying different levels of sodium sulfite at constant ratio of Na2SO3/Na2CO3 of 3/1, and three pulping times. Then pulping yield was analyzed and pulps produced at 8-16% sodium sulfite (2% intervals) and 20 minutes pulping time were selected for further evaluation. In addition, three pulps produced with application of 12% sodium sulfite and 20, 40 and 60 minutes pulping times were also evaluated. Pulps were refined to 400 ml CSF and then handsheets were made. Tear index varied between 6 to 7.5 mN.m2/g and tensile index at 35.6 to 66.5 N.m/g. The effect of chemical charge as well as pulping times, on both tear index and tensile index was significant 95% level. Furthermore, lower yield pulps, showed higher values for both properties and tear index increased with increasing tensile index.

Earthworm activities have an important effect on soil physical and chemical properties, soil fertility and plants growth. The number of studies about interactions between environmental factors and earthworms has strongly increased during last decade, showing the importance of earthworm ecology. Earthworm biomass is a suitable indicator for detecting trends in soil fertility, hummus quality, pollution and soil productivity. There is limited information on earthworm abundance in forest types of the Caspian region and it's relation to soil characteristics. Abundance and vertical distribution of earthworms within 20 cm depth of some forest types in Shast-Kolateh were determined and compared in this study. Nine forest types were investigated including Beech, Beech-hornbeam, Hornbeam, Oak, Oak-hornbeam, Alder, Maple, Ironwood and Ironwood-hornbeam. In each forest type, 10 soil samples (50×50 cm) were taken by digging into 20 cm depth and earthworms hand-sorted from 0-10 and 10-20 cm layers. Soil samples were taken from each layer simultaneously to measure physical and chemical properties including texture, moisture, bulk density, pH, nitrogen, organic carbon, K, P, Ca and cation exchange capacity. The number of earthworms was between 37 and 154 ind/m2 while thier biomass was between 5.9 and 12.1 gr/m2. Approximately 86 and 82 percent of earthworm number and biomass were found in 0-10 cm layer, respectively. The result indicates that forest types can be classified according to potential of stand productivity using earthworm abundance. According to this study, the forest types can be classified into three groups. The most important factors determining earthworm abundance and vertical distribution were soil pH, moisture, C/N ratio, phosphate amount and soil texture.

The Alborz Mountains in northern Iran exhibit an extremely asymmetrical distribution of precipitation and ecological forest types. The northern slope of the Alborz Mountains which is exposed to the Caspian Sea receives abundant rainfall during all seasons, whereas the southern slope suffers from dry conditions during the summer months. Current investigation compares the growth patterns of Quercus macranthera and Juniperus polycarpos that cover the northern and southern slopes of the Alborz Mountains, respectively. Ring width chronologies of oak and juniper cover the last 400 years. The relationship between climate and tree-rings width was studied by correlation analysis and response function analysis between the chronologies and climate data from the nearest meteorological station. Precipitation during the growth season is the most important factor determining Juniperus ring width. For Quercus, however, temperature is more important. The different growth limiting climate factors can be used to reconstruct different aspects of climate change in the study area and to combine information about precipitation history with the history of temperature change. The juniper and oak chronologies are positively highly correlated with each other during the period 1805 until 1954. During the last 50 years (from 1955 until 2004), the patterns of growth similarity decreased between the two species. Presumably this is a consequence of intensified cattle grazing and the pruning of trees which is extensively practiced in the oak forest. Thus, beside the reconstruction of past climate variability, tree-ring series from this ecologically sensitive mountain environment can be used to indicate changes in landuse intensity.

In this study,Alder (Alnus subcordata) and Oak (Quercus castanifolia) barks were extracted with sodium hydroxide (1% NaOH) at temperature (in two levels of 60 and 90oc) and extraction time (in three levels of 15, 60 and 120 min). The purpose was to determine the effects of temperature and extraction time on yield and polyphenolic compounds. Data were statistically analysed with SPSS Software in multifactor analysis and Duncan's test were used for mean's comparison in levels of 1 and 5 %. Temperature increase caused increase in yield and polyphenolic compounds of both species. The extraction time increasing had positive effect on yield and polyphenolic compounds but there was not significant difference between two extraction time 60 and 120 min and they are in same groups based on Duncan's test. Therefore the best condition of temperature and extraction time are 90oC and 60 min. The yield of oak extractive materials (24.07%) is much more than alder (21.44%) while the polyphenolic compounds of alder (19.35%) were obtained higher than oak.

In this study, the feasibility of utilization of old corrugated container (OCC) and wood fiber on the surface layers of three-layer particleboard was studied. The effects of variable factors including mat moisture content, content of adhesive and type of materials in the surface layers were assessed on the operational properties of manufactured particleboards. The results indicated that moisture content has significant and more prominent effect on the properties of particleboards. Increasing moisture content from 10 to 14 percent and adhesive content from 10 to 12 percent resulted in increasing modulus of rupture and modulus of elasticity and decreasing shear strength. Utilization of wood fiber on the surface layers in comparison with OCC fiber improved the modulus of rupture. Water absorption and thickness swelling after 2 and 24 hours are decreased when using wood fiber with low moisture content and low adhesive content in the surface layers.

Dead wood (dead trees and snags) is regarded as an important ecological component of forests, yet its status in the Caspian forest has gone largely unreported. Composition of dead tree was studied in a series of sites in the Caspian forest in north of Iran. The aim was to compare the amounts of dead wood and snags in forests with historically different intensities of management: in a region with long term implication of management (Patom), short long term implication of management (Namkhaneh) which was compared with virgin forest data. 215 individual dead trees were recorded and measured at 79 sampling locations. The virgin Forest generally contained greater mass and volume of dead tree. The results showed that the stocking volume of alive and dead trees are 328 m3/ha and 3.2 m3/ha in Patom district and 517 m3/ha and 5.17 m3 /ha in Namkhaneh district, respectively. Beech trees constituted the most alive trees, whereas most of dead trees were hornbeam. The results showed that composition of a live tree around dead wood was different from composition of dead wood. Comparing amount of dead wood in three sites showed that, dead wood volume related with management history. Reaching their highest amount in virgin site and their lowest in a region with long term implication of management, it was identified that forest management cause reduction of amount of dead wood on the study region and then affect the forest ability to generate dead wood specially in a large size. Thus managing this forest according to ecologically sustainable principles require a commitment to maintaining stand structure that allow, continued generation of dead wood in a full range of size.

Power distribution tightly affects the manner of sources and possibilities distribution that its main reason is creation or elimination of internal and medial coordination of institutions. Codified development documents of Iran show that the planned objectives in natural resources section have not been successfully operated. So this research has tried to find the reasons of these failures through investigation of power structure in legal network of formal institutions with "New Institutionalism Theory". Network of legal authorities of formal institutions related to natural resources in national and provincial (Kohgiloyeh va Boyerahmad) levels was delineated with "Network Analysis" through UCINET and Netdraw Softwares. Also the analysis was done with known indicators of Network Theory (Centrality, Degree, Power, Cut points…). The results show that at first there are not strong relations between coordinator institutions and between them and implemental institutions. Secondly there is not a distinct border between the stage of strategy codification and their implementation in Forth Development Plan. Also in Development Plan of Kohgiloye va Boyerahmad Province, there is not any common legal relation between Administration of Environment Conservation and Administration of Natural Resources with other institutions that it is against of two national documents in which Organization of Environment Conservation is the main power. In spite of efforts in order to increase the governmental body, non-governmental institutions are not located in appropriate position in these tree documents. So, for policy-makers and planners, it is necessary to pay more attention to commensurate distribution of power between institutions in national and provincial level through codification of next development documents.

Production and costs of loading in planned and unplanned (conventional) logging were assessed in this research. Parcels no. 23 and 25 in district no 2 of Asalem Forest were selected for this study. System hourly production was calculated using work study technique based on IUFRO guideline and hourly cost is calculated using work study technique based on Iranian Forest and Rangeland Organization. The results showed that planning skid trails and landings before felling operations increased hourly loader production from 25.3m3 to 38.9m3. Increased production reduced loading costs per m3 from 37687Rials to 23575Rials. These loading costs include landing construction cost in planned harvesting and road maintenance cost unplanned harvesting.