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Unit 2
Tree and wood
Cross-section of wood and me name of
different parts:-
# Types of wood
a)Hardwood: Those type of wood which
are used for structure loading purpose
for building sre called hardwood. Eg.sal, Sicau, Mongoo, deodar etc.
b) Softwood: Those type of wood which are used for ornamental purpose is called softwood These type of wood is easy work upon. Eg. chir, walnut and sallo.
# Types of tree
a) Endogenous Tree:-
⇒These free type of tree usually grow from pith or internally. Endogenous free usually grow radially rather than length. Eg sal, Siasu, deoder etc.
b)Exogenous Tree:-
⇒These type of tree grow on height rather than radially. These type of tree are used for piers, small foundation and cottage Eg Bamboo.
Important trees found in Nepal:-
Chir:-It is generally found in himalayan
region at height of (2500m -5000m)
Properties
→ It is pole grayish and yellowish color.
→ It's weight is 560 kg/m²
→ It can be easily worked.
deoder:- It is a fall tree which with pointed
leaves found in 1000m - 3000m range.
Propeties
→It's color is yellow but becomes dark yellow if exposed
→It's weight is 560 kg/m³
→It can be easily worked.
sal: It is found in sub-himalyan region
and in inner terai region.
Properties
→It is pale brown in color and gets dark
in exposing:
→It's weight is 860 kg/m³
→It is not easy to work upon and used
for loading purpose.
Sisau (Shisham):- It is wide avibilable in
teral region of Nepal. It is one of the most
valuable free of Nepal.
Properties
→It is dark brown in eto color with golden
steaks.
→It's weight is 880 kg/m³.
→It is hard to work upon and it is much
durable.
Growth of Trees
⇒A tree becomes taller only through growth.
at tips of the branches. It becomes thicker
through formation of cells. Just within
inner bark. A few annual rings next
to the bark are less mature but more.
active than heart wood and known as
sap wood. Heart wood is more resistance to the decay.
⇒In Spring season roots of the tree abcorts a solution of call from the sail, which is food for free and transmit the same calt through the trunk of free to its branches and leaves This solution of salt loose some of the moisture because of evapouration and absorb carbon dioxide from air. This action in the presence of sun makes salt solution a bit viscous. which is known as Slowly, sap changes into wood and form annual rings.
* Time of felling tree:-
1) If refers to process of cufting down of tree.
2)Felling can cause injury and serious damage when proper process is not considered.
3) Before falling of free we should be well planned.
4)Tree should be cut into the direction where can easily make the log of tree.
Method of felling tree:-
⇒ There are two method to cut down the tree in safe way:-
1) Notch cutting:
⇒Notch is an opening cut made in direction of felling. The inclined out at 75⁰ and 45⁰ at both top and bot buttern of trunk. After that the force is applied to the direction of felling.
2. Felling cut:
⇒ It is the car level cut starting from back of notch towards the notch.
Tools requried for filling of free
1)Hands tools
i)Axe:- Primitive tools used for felling and
spliting.
ii)Chain saw:- Portable mechinized used for cutting of large tree.
iii)Cross cut saw:-Saw that have teeth that are designed to cut wood at a right.
iv)Back saw:- A type of crase
person to back felled tree into log.
Defination of part of trees
1)Heart wood:-
⇒It consists of the inner annual
links around the pith. It is composite of
strong dark and durable. The heart wood
increases when increase in growth of tree.
2)Sap wood:-
⇒ The outermont onnual rings between
heart wood and combium layer. It is light
in color and weight and easily effected
by decay.
3)cambium layer:-
⇒ The thin layer below bark and covered covered by inner bark.
4) Inner bark:-
⇒It is the inner skin or lager covering the cambium layer. It protects combium
from turmite and decay.
5) Outer bark:-
⇒The outermost cover and consists of wood fibers. It prevents the tree from internal injuries and weathering.
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