Forestry Calculations and Practices

Posted on May 20, 2024 in Other subjects

Forestry Calculations

Harvesting Costs

Total Costs/SMH = (fixed costs) + (variable costs * UT%) + (labor cost)

Fixed Costs = (depreciation) + (II&T)
Depreciation = ((Purchase price) – (Purchase price * Salvage Value%)) / (Useful Life * SMH/year)
II&T = (II&T% * AVI) / (SMH/year)              M&R = (M&R% * Depreciation) / (Utilization%)
F&L = (Fuel Consumption * Fuel Price)(1 + Lube%)    Labor Costs = Wage rate(1 + Overhead & Fringe %)
Harvesting Cost($/ton) = (Total Costs/SMH) / (Productivity)
Productivity(tons/SMH) = ((tons/PMH) * (Utilization %))
Break-even Production Level(BEP) = (Fixed Costs/day) / (Selling Price/ton – Variable Costs/ton)
FC/day = (total FC/year) / (working days/year)      VC/ton = (total VC) / (total tons)

Pipe Sizing

Cross-sectional area of pipe required in ft2(A) = (runoff co.(C) * Watershed acres(M))0.75
Diameter of pipe = SQRT(A/.005454)    *Always round UP to the nearest even numbers!*
C = 1 for impervious, .7-.8 for steep slopes moderate runoff, .5-.6 for moderate slopes dense cover, .3-.4 for gently rolling ag land, .2 for highly pervious soils

Gravel Calculations

Volume of Gravel ft3 = (miles of road)(5280 ft/mi)(road width in feet)(gravel surface inches / (12 in/foot)
Tons of gravel = (Volume of Gravel ft3 * Gravel Weight lbs/ft3) / (2000 lbs/ton)
Cost of gravel = (tons of gravel * $/ton)

Curves *D in not DELTA*

DELTA = (FS – reverse BS)
Choose appropriate D for the situation… *round it to closest number divisible by 4*
D = E of a one degree curve / Desired E
D = T of a one degree curve / Desired T
D = 100(delta) / Desired L *L is desired tangent length*
D = (Radius * degree) / R
R = 5729.65 / D
T = (T of 1 degree curve *use DELTA to find this*) / D
E = (external *use DELTA to find the external*) / D
L = (100 * DELTA) / D
LC Bearing = PC Bearing (if frontsite), = flip of PC Bearing and subtract DELTA/2 to closest 90 Deg. which would be north or south (for backsite)
PC Station = PI – T        *6+5555 = 655.55(express PC station in this nomenclature)*
PT Station = PC + L        *use same nomenclature as PC station above)


Deflection Angle = D/4         Tangent Distance (TD) = sin(2 * deflection angle) * R
Tangent Offset (TO) = 1 – cos(2 * deflection angle) * R

Forestry Practices

Harvest Planning Steps

Harvest Planning steps:
  1. Reconnaissance
  2. Identify and Mark SMZ’s
  3. Locate and Flag landings
  4. Locate and Mark Stream Crossings
  5. Locate and mark log truck entrances to public roads
  6. Locate other logging road control point
  7. Locate/flag gradeline
  8. Locate and mark designated skid trails
  9. Specify logging road construction standards
  10. Specify stream crossing structures, if applicable
  11. Determine schedule of operations and harvest plan
  12. Specify tract “close-down” requirements.

US Forest Service Gate System

US Forest Service Gate System:
  1. Gate 1 – initial planning
  2. Gate 2 – project analysis, assign, and decision notice
  3. Gate 3 – sale prep
  4. Gate 4 – advertisement
  5. Gate 5 – Bid opening
  6. Gate 6 – Timber sale contract award

Independent Contractor vs. Employee

Independent contractor:
  • Self-employed
  • Subject to self-employment tax
  • Contractor decides how and when work is done based on contracts with client.
Employee:
  • Employer controls what will be done and how it will be done
  • Determination is based on preponderance of evidence.
Why hire employees?
  • Control over job
  • Known and consistent price
Why hire contractors?
  • Only hire for work when needed
  • Avoid overhead costs of employees
  • Reduce liability (contractor will generally be liable)
  • Increase flexibility (contractor has freedom to innovate and may be more efficient)

Road Cross-Sections

4 basic road cross-sections:
  1. Cut-and-fill: gentle slopes (<50%)
  2. Full bench: slopes >50%
  3. Through-cut: prevent excessive grade, high traffic roads
  4. Through-fill: flat terrain, wetlands

Road Shapes

4 basic road shapes:
  1. Outsloped: cheapest, no ditches needed, may require seasonal closure, can be dangerous if slippery, use when grade is gentle (<8%) and traffic is low and rutting can be controlled
  2. Insloped: road sloped in towards uphill side of terrain into a ditch that drains out, use when grade is steep or slippery conditions
  3. Crowned: water drains off both sides of road, water moved to downhill ditch with cross-drain culverts, used when 2 lane road is needed or its a single lane road on very steep terrain, requires regular maintenance of ditches.
  4. No Shape: forest road, usually on small private lands, create environmental damage because they usually hold water and rut badly.

Drainage Options

Drainage Options:
  • Water Bars: best for closed roads/skid trails, not designed to be driven over, minimal maintenance, easy to install with bulldozer.
  • Broad-Based Dips: permanent roads with skid trails, not effective when road grade >10%, gravel often necessary on high volume roads, must maintain dip.
  • Rolling Dips: carry water from inside to outside of roads, light to moderate traffic, difficult to construct properly.
  • Water turnout/Diversion ditches: permanent or temporary roads, skid trails, used to divert water from road to skid trail, diversion ditch should always go downhill, locate turnout away from wetlands and streams, should trap sediment at end of turnout.
  • Cross Drain Culverts: Divert water from uphill side of road to downhill side, often used with insloped roads, culverts require maintenance to prevent clogging.

Harvesting Systems

3 types of harvesting systems:
  • Whole tree: tree brought to landing with branches in tact
  • Tree-length: delimbed and topped before arrival to landing
  • Cut-to-length: trees are delimbed, topped, and bucked before arrival to landing
(-In the South, fully mechanized whole-tree systems dominate. Tree-length systems dominate in the mountains due to reduced weight to drag across steep terrain.)

Logging Business Types

Logging business: harvests and delivers timber to mills, owns timber
Harvesting contractor: harvests and delivers timber, paid per unit for timber, do not own timber
Wood dealer: buy standing timber and pay contractors to harvest and deliver to mills
Logger dealer: less common, owns equipment and buys timber to harvest for themselves
Stumpage: price paid to landowner for standing timber
Cut and haul rate: price paid to logging contractor to harvest and deliver
Delivered price: price paid for wood delivered to the mill (must cover all costs)
Whole tree southern systems: use 1 feller-buncher, 1-2 grapple skidders, 1-2 loaders.