Position and role of tension wood in trees - Case study: Eucalypts

One-year seedlings of five species of eucalypt: E. camaldulensis, E. microtheca, E. viminalis, E. globulus and E. gunnii were treated for 14 weeks in growth season, tilting a branch to c. 60° in every successful ones. We investigated the anatomical features of stems wood after 15 days and every 2 weeks according to IAWA list of features afterwards.The results showed that tilted stems formed more tension wood in the form of gelatinous fibers than straight (untreated) ones. The formation of gelatinous fibers was considered to be closely related to tension wood formation. The formation of gelatinous fibers was considered to be closely related to tension wood formation. Excluding E. globulus, all the other species formed growth eccentricity and tension wood. Although the significant differences between the species and between different locations in the branches, there were no significant differences between the percent of tension wood among the species studied

PROPERTIES OF EUCALYPTUS MICROTHECA WOOD GROWN IN SOUTHERN REGION OF IRAN

In order to investigate The properties of wood eight-nineteen-years- old trees of Eucalyptus microtheca from De-hnow exprimental Plantation located 160 Km. South west of Shiraz were selected randomly and fell two from each of the four blocks. From each tree, 10 cm thick cross-sectional discs at several different heights (3 metres intervals) were cut and together with remaining boles then transfered to the Alborz Research Center-Karaj for laboratory studies. The laboratory studies included determination of physical, anatomical and mechanical properties as well as chemical compositions of wood. The mechanical properties were evaluated on the ASTM samples for air-dry and green conditions. The following conclusions were drawn from this study:E. microtheca from one site in southern region of Iran has an average specific gravity of 0.804, fiber length of 0.811 mm, fiber diameter of 15.9 mm, lumen diameter of 5.7  mm, cell wall, thickness 5 mm, cellulose content of 44.47 percent.It was found that the mean values of modulus of rupture, modulus of elasticity and compression strength-parallel to grain tested at green condition were 72.50 MPa, 8066.6 MPa and 38.5 MPa and air-dried condition were 120.7 MPa, 12013.8 MPa and 69.80 MPa respectively.Data are also presented on other mechanical properties such as impact strength, nail withdrawal cleavage and e

EFFECTS OF ENVIRONMENTAL FACTORS ON FORMATION OF LIGNIN IN EUCALYPTUS CAMALDULENSIS DEHN. GROWN IN KHOSESTAN-IRAN

Peroxidases are enzymes which catalyse two final steps in the wood lignin biosynthesis. The connection between xylem peroxidase activities and wood xylem lignifications was examined by determining peroxidase activities in the stems of eucalypt (Eucalyptus camaldulensis Dehn.) trees during two seasons in 1999over the period of annual growth. In addition, samples from the same trees were examined for lignin content. This study clarifies the possible roles of this enzyme in lignin biqsynthesis and forms a background for further work on the last steps in lignin polymerisation. The peroxidase activity of some samples was lower in Autumn. But in the others there was a great increase in Autumn vs. Winter. Though in Autumn there were more isoenzyme. The results show a relation between lignifications and Peroxidase enzyme zones. In Eucalyptus camaldulensis Dehn. in khozestan

TECHNOLOGICAL CHARACTERISTICS OF SAXAUL WOOD IN IRAN (KERMAN PROVINCE)

To study saxaul wood properties in the various ecological regions of Iran twelve 10-22 years old sample trees (4 trees from each species) were selected and cut from three different areas around kerman. Physical, chemical and anatomical characteristics of wood samples were investigated. The results of this investigation revealed that the initial moisture content before felling was 38.6% and the mean specific gravity based on oven dry weight and oven dry volume (WOD/VOD), oven dry and saturated weight Saxaul saturated volume (WOD/Vs ,WS/VS ), were studied for yellow, white and black and respectively. It is concluded that saxaul wood of Kerman province is heavy. The average longitudinal, radial and tangential shrinkage were surveyed. Wood periodicity of growth was determined to be 3-4 rings per year. Anatomical features were investigated by light microscopy and papermaking factors were determined. Fiber length, fiber diameter and lumen diameter were determined. These values lead to species with short and thick fibers. Chemical composition including percentage of cellulose, lignin, extractives and ash were revealed too

Investigation on potential of few eucalypt species for absorbing pollutants and reserv-ing them in their leaves

Trees as alive components of an ecosystem are able to convert some of the environment contaminants to unharmful substances and store some of them in their tissues and reduce their density and intensity in the air and soil by breath, root absorption and photosynthesis and other biotic functions. Trees function in such condition is completely related to environmental and habitat circumstances and their physiological potential. At beginning, five research sites at Khuzestan and Bushehr provinces were selected among the contaminated area by the Gulf War. At each site, soil sampling was made from three levels of depth (0-20, 20-40 and 40-60 cm). Soil physical and chemical characteristics test was made to measure nine metal elements and 12 other soil properties. The eucalypt species consisted of: E. camaldulensis, E. camaldulensis 9616, E. microtheca and E. sargentii which were planted under the Randomized Complete Blocks statistical design with three replicates. Before sampling the trees for determining the contaminant elements. Three individual trees were selected at each plot per one replicate to make sampling for leaf (four specimens per tree at four mean geographical directions). The data were analyzed under the variance analysis and Duncan test programs, using Excel and SAS computer soft wares. Overall, amount of the contaminants in different sites and at three levels of depth was not significantly different. The best eucalypt species and the best sites for absorbing the contaminants in their leaves are respectively as follows: 1-       E. camaldulensis, E. microtheca, E. sargentii and E. camaldulensis 9616 2-       Dezful, Isvand, Shooshtar, Karkheh and Kaki. The species which made the best performance in relation to their site interaction are respectively as follows: 1-         E. microtheca firstly at Karkheh and shooshtar sites and secondly at Dezful and Isvand sites. 2-                        E. camaldulensis 9616 3-                        E. camaldulensis and E. sargentii