FORE205 Flashcards
forestry eng
NZ logging
Before people arrived, >80% of land was forest.
Devlopments major issue
Timber harvesting and extraction has always
been, and still is, a major cost in managing
forests.
Exotic trees nz logging
Due to increased demand, exotic trees were then
planted.
Protests started in 1970’s to stop native logging and in
2002 logging on public land stopped
Developments in extarction
People to animal
Gravity
Tracks
Waterways
Cable ways
Wire rope
steam donkey
Railroad
Rubber tires
Developments in harvesting
Chainsaw
Bulldozer Extraction
BIg wheel
Prioties in forestry
Safety and Enviromental
Modern systems
Automated cable system
Helicopters
Future
Automated Yarder
NZ native forestry
Native…
25% of land area. Heritage
values, natural wealth,
environmental benefits
Nz production Forestry
Production…
7% Land area in plantations,
90% Pine.
Primary reasons for harvesting
Economic and silvicultural goals
Economic goals??
timber value, land values
Silvicultural Goal??
*Timber stand improvement
*Stand improvements for wildlife, residual stand value, Species manipulations, salvage
* water/snow yields
Harvesting
Activity of picking and collecting
crops, or of collecting plants, animals, or fish as food
: any time we take timber from a forest. Collecting implies we
maintain possession of the produce – so cutting a tree down and
leaving it there does not apply (i.e. thinning to waste).
Forms of harvesting
Clearfell, Coup harvesting, Group selection, Individual tree selection (mature trees) Production thinning (mature trees )
Non- commercial forestry values
▪ Water quality
▪ Reduced soil erosion
▪ Increased bio-diversity
▪ Recreational opportunities
NZ current issues
ETS, Harvesting residuals in waterways (slash), terrian
6 Step harvesting process
- felling 2.processing 3.Extraction 4.Processing 5. Loading 6.transportation
Felling
” to sever the tree and bring it down”
Felling considerations
- without reducing the value of the stem
- in a manner that aids subsequent operations
(processing or extraction) - with minimal impact on the site
- with minimal impact on
advanced regeneration - with minimal obstructions
for site preparation
Factors affecting felling
▪ Type of Cut
▪ Stand Characteristics
▪ Timber Size
▪ Timber Density
▪ Underbrush
▪ Terrain / Topography
▪ Ground Conditions
▪ Subsequent Operation
▪ Labour Availability
▪ Weather
Felling options motor manual
Chainsaw
Chainsaw safety
- Hardhat (helmet)
- Visor (sunglasses)
- Earmuffs (hearing protection)
- High-viz shirt
- Cut-resistant trousers (chaps)
- Steel capped (kevlar lined) boots
Chain saw advantage
low investment cost
less impacted by site
less impact on site
easy replacement
Chainsaw disadvantage
very dangerous
low volume output
labor intensive
possible damage to log (less control)
Felling cuts
Conventional, humboldt, open face
Felling options: mechanised Advantages
▪ more productive
▪ safer
▪ easier on operator
▪ control of tree
▪ higher visibility
Felling options: mechanised disadvantages
higher capital costs
▪ reduced flexibility
▪ possibly more site impact
▪ affected by site condition (steep, wet)
▪ limited by tree size
▪ more maintenance
Felling options: mechanised characteristics
▪ Carrier type
▪ Swing-to or Drive-to
▪ Shears, Hotsaw or Chainsaw
▪ Felling-head, Feller-Buncher or Felling
Processing Head
Carrier types
▪ Tracked machine
▪ Wheeled machine (3 or 4)
▪ Purpose built (harvester)
▪ Excavator base
Shears vs Saws
Shears advantage and dis
Advantages:
low stumps, low maintenance
Disadvantages:
butt damage, stump pull, offsets,
shatter, barberchair, splits
difficult in hardwoods
Shears vs saws
Saws advantage and dis
Hot-SAWS
Advantages:
Fast, minimal butt damage
Disadvantages:
higher stumps, large curf
heavier, maintenance
Felling head types
▪ Felling Head
▪ Simplest, just fells
▪ Feller-Buncher
▪ Can fell & hold multiple trees
▪ Feller-Processor
▪ Can multi-task: fell,
limb and buck
De-limbing and function
removing the limbs from the stem
TOPPING – cut top at the specified diameter
Both functions: are driven by market destination & should not
degrade the value of the tree
Limbing mechanical
▪ gate delimbers
▪ delimbing rakes
▪ pull-through delimbers
▪ stroke delimbers
▪ grapple processors
▪ chain flail delimbers
Bucking/ crosscutting
– cutting the
tree into logs or bolts.
Bucking/ Crosscutting decision determined by….
Timber size
market demands
Transportation restrictions
MAXIMISE STEM VALUE
Deciding system use
Physically feasible
Socially acceptable
Economically viable
Extraction (yarding)
Ground-based
“Extract timber by moving power machine (or
animal) into, and out of, the stand”
Extraction (yarding)
Cable
▪ “Extract timber with power machine in stationary
position pulling logs from a distance by means of a
wire rope cable wound on a drum”
Extraction (yarding)
Aerial
“Extract timber using aerostatic or aerodynamic lift”
Ground based system e.g
- Animal
- Crawler Tractor
- Rubber-tired tractors (straight frame)
- Rubber-tired articulated skidders
- Excavators
- Forwarders
FACTORS AFFECTING THE
SKIDDING / FORWARDING OPERATION
- type of harvest
- felling method
- distance
- tree size
- volume per hectare
- terrain
Skidding…..
moving the tree
from the stump to
the landing with
all or some part of
the tree in contact
with the ground”
Skidders advantage
- Most common
- High production
- Safe
Skidders disadvantage
- High capital and
running cost - Potential for higher
env. impacts
Tractor/ bulldozer advantages
- Robust
- Steeper slopes (40%)
- Greater tractive
efficiency - Can make skid trails
Tractor/ bulldozer disadvantages
- Slower
- Potential for higher
env. impacts
Shoveling
“lifting the tree from the
stump or bunch, rotating towards the road
or landing and placing the tree in a new
bunch”
(Either by partial or full suspension)
Shoveling advantaged
- Simple
- Steeper slopes (40%)
- Low cost
- Low ground disturbance
Shoveling Disadvantages
- Slower
- Best for clear cuts
- Limited to ≤150m
(5 swings)
Forwarding
“moving the tree from the
stump to the landing without the tree
touching the ground”
Forwarder advantages
- Lower env. impact
- Pre-sort in forest
Forwarder disadvantegs
- More expensive
- Lower productivity
Agricultural tractor advantage
- low capital cost
- easy to operate and plan
- suited for thinning
Agricultural tractor disadvantage
- safety (not legal in NZ)
- low production (20t –
50t/day) - Higher extraction cost
(approx $25 -$60/ton)
Animal systems advantages and disadvatages
Advantages
- Perceived to be low impact
- Low capital cost
- Self-regenerating…
Disadvantage
- Working with an animal!
- High maintenance
How to improve enviromental performance
▪ wide(r) tires
▪ tracks
▪ hydro-seeding
▪ mats
▪ bridges
Skidder cycle
One ‘turn’ for retrieving a load…
4 phases: Drive out – Accumulate – Return – Unload at
Landing
SMH
Scheduled Machine Hours (SMH)
- all time machine is scheduled to work
PMH
Productive Machine Hours (PMH)
- time that the machine actually performs work (primary task)
PMH = SMH – delays
PMH / SMH = % Utilisation
