Journal of Wood and Forest Science and Technology
Year:2009 | Volume:16 | Issue:4|Papers Count:10

Current increment of forest trees is affected by inner factors, environmental factors and the time. Rate of annual growth differs in tree living periods on the basis of fluctuations range, durability and effect manner of mentioned factors. The present study was performed to findout if there is homogenity in diameter increment of Beech trees (Fagus orientalis L.) in different ages, living periods and diameter classes. For this, 30 sample Beech trees in different diameter classes were cut from Haftkhal forest project. One disk with 10 centimeter thickness extracted on dbh level of each sample tree. After measuring the width of the rings, the regression of the age and radial increment variations fitted for each tree. Primary results show that trend and model of the tree increment change in its living periods. Statistical descriptives and growth models of the trees have Significant. difference in the same diameter classes. For decreasing the number of equations and aggregating them, stratification method was used. Sample trees stratified in ten groups upon three criteria: diameter classes, age and the mean of current annual increment (rings width on dbh level). The regression of the age and radial increment variations fitted for each group. All groups were compared by means test and increment distribution corresponding to tree age. According to the results, diameter increment models of the Beech trees are not homogenous. Thus, for estimation the Beech stand increment, trees must be divided into ten groups.

The interaction between landscape and forest properties has been well documented, and thus it is plausible to assume that landscape factors in a forest region have a determinant function in forest properties formation. Although previous researches have identified the significant relationships between forest attributes and environmental factors, but there is no definite model available for this properties delineation. Utilizing digital terrain models and its extractable information can help for this purpose. This study was conducted to evaluate artificial neural network ability for prediction spatial distribution of forest tree density and for production continuous map using primary and secondary topographic attribute in Shastkolate forestry plan, district I. The primary and secondary topographic attributes calculated from digital elevation model with 10m resolution. Geometric coordination of plots which were recorded by GPS, mapped in GIS. Then Primary and secondary topographic attribute derived in this plot location. Tree density obtained by counting number of tree in 1 Are circle plots and then calculation in hectare. The relationship between forest tree density and terrain attributes analyzed applying two types of artificial neural network (MLP and RBF). Results showed that RBF neural network provides more accurate results than MLP neural network. Moreover, the regression analysis was done for comparison of the results of ANN models with linear models. The results verified the ability of artificial neural network for prediction of forest tree density and also indicated that ANN approach can predict approximately 65% of the forest tree density variation in the given study area using topographic attribute.

Tree felling is one of the most important components among tree harvesting components which consists of cutting and felling, limbing and bucking sub-stages. Tree limbing using chainsaw in hardwood forest is much effective and important. This research was carried out in two compartments of Namkhaneh district, in Kheyrud Forest for assessment of limbing sub-stage. The objectives of this study were time study of tree limbing operation, estimating the productivity and costs of chainsaw and developing regression model. Factor affecting total limbing time regression model was dbh of harvested tree. The hourly production of chainsaw limbing with and without delay time were 11.1 m3/h (4 tree/h) and 14.8 m3/h (5 tree/h), respectively. Productivity of chainsaw tree limbing is increasing with dbh as power. The unit cost of chainsaw limbing with and without delay time were 14710 and 11020 Rials/m3, respectively. Total tree limbing cycle time without delay averaged 12.37 minutes and with delay time averaged 16.51 minutes and also with reducing personal delay, work efficiency can be increased.

The soil and vegetative characteristics are so closely interrelated and interactive, in a region that, the study of one factor without considering the other one, is somehow worthless. This paper attempts to evaluate the effects of flood spreading on some soil properties and vegetative characteristics of: Nubk, Common mesquite and Gum arabic in mixed man-made forests. Three sections of the forest (300 hectares of the total flood spreading networks) were selected, in such a way, to be representative of the whole forest of region, at Tangestan flood spreading experimental station at Bushehr province. To evaluate the effects of flood spreading at elevation levels, each section of forest was divided into, two; upland and downland subdivisions. At each section six soil profiles (a total of eighteen profiles) were dug and the phisico-chemical properties were assessed. To evaluate the forest stand changes, basal area per hectare and percent crown canopy were estimated. A cluster sampling design, with 1600 square meters plots (40×40 meters), with an orientation of 4 plots around each profile was used. The field data and laboratory results were analyzed. The comparison of soil properties indicated that, sand percent, clay percent, silt percent, acidity, electrical conductivity, nitrogen, phosphorous and potassium amount have a significant difference among sections. Section one had the highest results and showed a better condition in relation to the others. The results indicated that flood water spreading had different effects on vegetative characteristics. The comparison of flood water spreading units indicated that percent crown canopy at downland subdivisions exhibits a more favorite condition than upland. Mean basal area per hectares in section one is higher than the other sections.

Mixed Office Waste DIP produced at Latif Paper Company was used as reinforcement pulp to substitute part of imported long fiber pulp in White Poplar APMP furnish produced at Maraghe Paper Company. Each pulp was separately refined to about 250 CSF and then, handsheets were made applying 0(control sample), 5, 10, 15, 20 and 25 percent DIP mixed with APMP and LF pulps. The control sample contained 30 percent LF and 70 percent APMP pulps. Mechanical and optical properties of the handsheets, including tensile, tear and burst strengths, brightness and opacity were determined according to relevant TAPPI standard test methods. Comparison of the data was done using ANOVA and the best treatment, was determined using scoring method based on normalization equation. The results showed that 5 to 15 percent Mixed Office Waste DIP can be properly used in mixtures with 15 to 25 percent LF and 70 percent White Poplar APMP pulps to produce writing and printing paper with suitable mechanical and optical properties.

This research was carried out in a reforest at Shirvan Agriculture College in two years (2005-2007). The aim of this research was to determine of canopy interception loss, throughfall and stemflow. Four trees species were used including pinus nigra, Cupressus sempervirens, Robinia pseudacacia and platanus orientalis with three replications. The results showed that the amount of canopy interception loss, throughfall and stemflow of pinus nigra and Cupressus sempervirens was 34.77, 63.73, 1.43 and 44.97, 53.08, 1.63 percent, respectively. These amounts for Robinia pseudacacia and platanus orientalis species were 9.78, 89.42, 0.8 and 5.5, 93.97, 0.53 percent, respectively. There was a significant difference in canopy interception loss between pinus nigra and Cupressus sempervirens (P<0.05). However, there was no significant difference (P<0.05) in interception loss between Robinia pseudacacia and platanus orientalis species. Furthermore, a significant difference (P<0.01) was observed in interception loss between evergreen and deciduous trees. The results showed that Cupressus sempervirens had the highest interception loss than other trees species.

This study was conducted to investigate the properties of NSSC pulp from seed original stem and second-growth of Eucalyptus camaldulensis. Cooking conditions were as follow: time 30, 60 and 90 minutes, Temperature 165oC and L/w: 6/1. Na2SO3 and NaHCO3: 15% and 7% based on OD weight of wood, respectively. In this study fiber dimension and chemical compositions of woods were determined. The pulps were refined to reach the target freeness value (400ml, CSF). Then, hand sheets were made and tested. The average pulp yield for seed original stem wood was higher than the second-growth wood. The results of the strength properties indicate that all properties of the pulp produced from seed original stem in the same condition are higher than those of the pulp of the second-growth wood, but there was no significant difference between them. However, regarding to the results in terms of fast-growth, higher pulp yield and lower refining energy required to reach the proper freeness value, make the second-growth wood as suitable as the seed original stem wood in pulp and paper industry.

The endocarp of Celtis australis L. with hyrcanian forests of Northern Iran and arid mountains of Northern Africa ecotypes were studied considering macro and micro morphologic characteristics, using binocular and Scanning Electron Microscope. The aim of this research was to evaluate the endocarp diversity in different ecological conditions. The results showed that Celtis australis L. is bigger, softer, with holes with 10 micron diameter in Iran; but, the African Celtis australis L. endocarp is smaller and rougher having two enclosure circles and without hole in outer layer. The total results show endocarp characteristics is dependent to the ecological conditions, and is coutinuesly changing with its changes.