2020 Flashcards
Tree coverage %
31%
Aus forest description
- Australia has one of the largest and most diverse forest ecosystem consisting of 125 million hectares.
- A large percentile is native with hardwood trees such as Eucalyptus dominating land coverage.
- 600 species of hardwood
Aspects of forest management
1) thinning = remove every 2nd tree as they grow
2) pruning = selectively removing parts of a plant
3) fire protection = remove potential fire fuel
Reafforestation
The replenishment of depleted forests and woodlands. This process often occurs after deforestation. Can happen through silviculture of dropping seeds.
Silviculture processes
Clear felling = felling the whole of the useable crop at the one time. Area is often cleared and trees replanted or natural growth can occur
Selection = Felting just the largest or specific trees as they mature, leaving smaller ones to develop.
Grouping = The process of not removing single trees but whole groups of trees. Up to 1 hectare
Hoop pine
- softwood
- light yellow to almost white
- even texture with no pronounced growth rings
- durable in wet conditions
used for interior joinery, cabinetwork and mouldings
Timbers commonly important into Australia
- Oregon
- Meranti
- Fijan mahogany
5 by-products of timber
Building Boards = particle board, hardboard, soft board, medium density fibreboard
Sawdust = can be used in fuel, insulation, packing, stuffing. Up to 20% is made into sawdust from aloy
Paper pulp = wood is cut into chips, ground and pulped in water and chemicals to bind fibres. Then compressed
Chemicals = Creosote, methanol etc. produced by distillation process.
Plastics = Source of cellulose from which plastic materials may be viewed.
Function of root system
1) anchor tree into ground to combat elements
2) extracts water and nutrients in form of mineral salts from the sail
The trunk
1) provides rigid support
2) carries water and food material to the crown
parts of a tree
- Cambium layer = food material travels to the branches, trunk and roots through this. it is responsible for growth in trunk thickness.
- Truewood = It provides necessary strength to support the tree. durable. made from dead cells
- bark
- sapwood = Water and mineral salts are conducted from the roots to other parts of the tree through this.
Photosynthesis
Photosynthesis forms sugar from CO2 and water in the presence of sunlight. This releases oxygen into the air..
requires chlorophyll
cross section of a tree
Outside to inside…
1) live bark
2) cambium layer
3) sapwood
4) growth rings
5) medullary rays = horizontal cells for food storage and conducting it radially. from the pith to out zones
6) truewood
7) pith = conducts food materials horizontally in the trunk of a tree .
Hardwood
Wood that contains large pores in its structure
tracheids
water carrier and bulk of wood substance
three substances present in cell structure
lignin
resins
gums
durability of wood
The ability of wood to resist decay, termites, borers and the weathering process. does not depend on hardness
texture
The property of wood that refers to the arrangement and relative size of cells.