Fizička i kemijska svojstva gorskog bambusa (Yushania alpina) uzgojenoga u Etiopiji

Bamboo is the fastest growing plant currently known on earth, a property that enables it to be the best alternative as a future source of wood fi ber. This study investigated the effect of site and culm height on the physical and chemical properties of Yushania alpina culms grown in Ethiopia. Matured Yushania alpina 3 to 5-year-old samples were harvested from Hagere-Selam and Rebu-Gebeya sites. The culms were subdivided into three equal lengths (bottom, middle, and top), and the variations in physical and chemical properties between the two sites and the culm heights of Yushania alpina were investigated. The results showed that the average values of MC, basic density, tangential and longitudinal shrinkage of Yushania alpina culms for Hagere-Selam and Rebu-Gebeya sites were (91.78 and 80.32 %), (0.65 and 0.63 g/cm3), (6.63 and 5.84 %) and (0.63 and 0.56 %), respectively. The average values of cellulose, lignin, extractive and ash contents in the culms for Hagere-Selam and Rebu-Gebeya sites were (52.84 and 50.71 %), (26.55, and 26.04 %), (8.41 and 8.02 %) and (1.95 and 2.17 %), respectively. The results revealed that the site affected the MC, basic density, cellulose, lignin, extractive, and ash contents of Yushania alpina culms but not the tangential and longitudinal shrinkage. The culm height of Yushania alpina affected MC, basic density, tangential shrinkage, longitudinal shrinkage, cellulose, lignin, extractive, and ash contents. In the case of both sites, the highest percentages of MC, tangential and longitudinal shrinkage, and ash content were observed at the base and lowest at the top of the culms. On the contrary, both sites observed thehighest magnitude of basic density, cellulose and extractive at the top and lowest at the base of the culms. The variations in physical and chemical properties at different sites and culm heights infl uence the utilization of Yushania alpina culms for industries and end products.Bambus je trenutačno najbrže rastuća biljka u svijetu, što je čini najboljom alternativom za budući izvor drvnih vlakana. Ovom je studijom istraživan utjecaj staništa i visine bambusa Yushania alpina, uzgojenoga u Etiopiji, na fizička i kemijska svojstva njegove stabljike. Uzorci Yushania alpina stari tri do pet godina skupljeni su sa staništa Hagere-Selam i Rebu-Gebeya. Stabljike su podijeljene na tri jednake duljine (baza, sredina i vrh) na kojima su istraživane varijacije fizičkih i kemijskih svojstava stabljike s obzirom na dva staništa i visinu bambusa. Rezultati su pokazali da su prosječne vrijednosti sadržaja vode, gustoće te tangentnoga i uzdužnog utezanja stabljike Yushania alpina sa staništa Hagere-Selam i Rebu-Gebeya bile 91,78 i 80,32 %; 0,65 i 0,63 g/cm3; 6,63 i 5,84 % te 0,63 i 0,56 %, a prosječne vrijednosti sadržaja celuloze, lignina, ekstraktiva i pepela sa staništa Hagere-Selam i Rebu-Gebeya bile su 52,84 i 50,71 %; 26,55 i 26,04 %; 8,41 i 8,02 % te 1,95 i 2,17 %. Rezultati su pokazali da je stanište utjecalo na sadržaj vode, gustoću te sadržaj celuloze, lignina, ekstraktiva i pepela u stabljikama Yushania alpina, ali ne i na tangentno i uzdužno utezanje. Visina stabljike Yushania alpina utjecala je na sadržaj vode, gustoću, tangentno i uzdužno utezanje te na sadržaj celuloze, lignina, ekstraktiva i pepela. Za oba staništa utvrđen je najveći sadržaj vode, tangentno i uzdužno utezanje te sadržaj pepela u bazi stabljike, a najmanji u vrhu stabljike. Nadalje, u vrhu stabljike s oba staništa primijećena je najveća gustoća, sadržaj celuloze i ekstraktiva, a najmanje su vrijednosti izmjerene u bazi stabljike. Varijacije fizičkih i mehaničkih svojstava s obzirom na stanište i visinu stabljike utječu na upotrebu stabljike Yushania alpina u industriji i za završne proizvode

Density and Seasoning Characteristics of Pinus caribaea Lumber Grown at Suba Forest, Oromia, Ethiopia

Determination of the seasoning characteristics, physical and mechanical properties of lumber species is helpful in identifying the main factors affecting the quality, suitability and overall performance of wood and wood-based products. The Pinus caribaea has been considered as industrial lumber species and there is a little study conducted in identifying the physical characteristics which on turn affects the quality of product derived from the lumber. Therefore, this study aimed at evaluating the density and seasoning characteristics of P. caribaea lumber. Sample trees were harvested from Suba Forest Oromia, Ethiopia. The experiments were carried out using air and kiln seasoning methods. To measure the initial moisture content, seasoning rate, shrinkage, wood density, and seasoning defects, six replicates of samples from each tree portions were prepared when green and promptly weighed. Analysis of variance (ANOVA) has been employed in interpreting the experimental results. The obtained results have shown that the mean initial moisture content for air stacks was 78.2% while for the kiln seasoning stacks 82.9%. Seasoning time for sawn boards of 3 cm thick to reach 17% moisture continent (MC) required 61 days, while for kiln seasoning took 4.3 days to reach 14.62% MC. This showed that kiln seasoning was about 14 times faster than air seasoning. In air seasoning the MC (%) of the lumber from 78.2% to 16.9%; and, the obtained mean values of shrinkages were tangential (3.6%), radial (1.9%) and volumetric (5.4%). The initial moisture content (IMC) and green density (GD) of the lumber were significant difference along the tree height at a 95% probability level. The seasoning rate % and final MC (%) along the tree height were significant difference at 95% probability level, while the seasoning rate % and final MC were significant difference between seasoning methods at 99% probability level. Seasoning defects such as cup, bow, twist, and crook were observed on kiln seasoned. In addition, end checks and splits were observed on air seasoned boards. Therefore, the experimental factors should be monitored and optimized properly to obtain the lumber with good quality and utilize it for different purposes, including construction and industrial applications