Wood Qualities Flashcards
Explain how auxin effects the production of early wood and late wood
Since auxin promotes cell growth and division and the transition to late wood takes place furthest away from auxin and proceeds upward, we can say that auxin inhibits the transition to late wood. In simple terms: auxin inhibits the transition of early wood to late wood.
What is the difference between early wood and late wood?
Early wood -Large diameter -Thin walled fibers and lots of pits for increased water permeability Late wood -thicker cell walls -less pits -provides rigid strength
Where does radial growth begin?
Near the top of the bole, proceeding downward.
What determines the density of wood fiber
The density has allot to do with early wood and late wood and therefore is largely affected by crown position and arrangement.
What is juvenile wood?
-Wood that is formed in the first 5-20 years of a trees growth -Lower density and shorter fibers than mature wood -Varies by stocking density and amount of live crown
What are some wood qualities and attributes? There were 8 listed in the lectures…
1.wood density 2.juvenile and mature wood distribution 3.fibrer length 4.fibril angle 5.compression wood 6.knots 7.grain 8.extractives
What units is wood density expressed in? What are some predictors of wood density?
G/cm^3 - predicted by ratio of juvenile wood to mature wood - sapwood to heartwood - early wood to late wood
What does wood density say about wood quality
High density equates to high quality Predictor of strength, stiffness, hardness, heating value and pulp/paper quality.
What does the fiber angle refer to
Fiber angle refers to the angle of the fibers in the secondary cell walls Juvenile wood 30 degrees in s2 High shrinkage(knotty) Mature wood 0 degrees less shrinkage
what has longer fibers? juvenile or mature wood?
mature wood has longer fibers, therefor is more desirable
How might a forester want to manipulate wood?
A forester would likely want to manipulate wood quality by designing stands for maximum mature wood synthesis. -This could be done by spacing trees apropriately so that their crowns would be concentrated near the top of the tree as it grows.
How is compression wood formed? What about tension wood?
forms as a response of a tree to a lean. So does tension wood typical on slopes that are moving -compression wood is formed on the leaning side of conifers to “Push” the stem up -tension wood is formed on the non leaning side of a hard wood and “Pulls” the stem up.
How are knots formed? how can they be avoided?
Knots are formed when lower branches die. The angle of their primary growth is different from the angle of the bole, creating a knot in the wood. They can be fixed by pruning the branch flush with the trunk. knot free timber will grow over the pruned or broken branch eventually.
What do knots do?
knots are a structural defect and reduce strength
What does grain refer to? What are the three planes of wood?
Radial - Top down Transverse - cut in half from the side (straight pattern) Tangential - cut in to a quarter ( oval grain pattern ) refer to p.36 in wood quality pdf if you dont get my explanation… it might be an idea to note the location of the rays, resin ducts and annual rings in the diagram but i doubt she will test on that…
