The Timber Harvest Cost Model estimates total delivered costs ($ US) from the stumpage to the mill gate for a timber stand. The two main components of the model are the harvest cost ($ US/cubic foot) and the hauling cost ($ US/minute) which are estimated by the model. Harvest cost ($ US/cubic foot) is multipled by the total volume (cubic foot) of the stand. Hauling cost ($ US/minute) is multiplied by the total hauling time (minutes) from the landing to the mill gate and by the total necessary hauling trips. Both together result in the total delivered cost ($ US).
- Harvest equipment move-in costs
- Road construction costs
- Management costs
- Reforestation costs
Requires xlrd, python-gdal, json, requests, and numpy
To install, simply python setup.py install or work directly from the root directory
See test_costmodel.py for an example of usage with the data in testdata.
The Main Model defines the cost function which is the primary interface; given information about stand attributes, tree attributes and routing, the cost function will estimate harvest and transportation costs.
from forestcost import main_model
main_model.cost_func(
# stand info
area, # Stand area (acres)
elevation, # Elevation (ft)
slope, # Slope (%)
stand_wkt, # Well-Known Text geometry of stand polygon
# harvest info
RemovalsCT, # Chip trees removed (trees per acre)
TreeVolCT, # Chip tree average volume (cubic feet)
RemovalsSLT, # Small log trees removed (trees per acre)
TreeVolSLT, # Small log average volume (cubic feet)
RemovalsLLT, # Large log trees removed (trees per acre)
TreeVolLLT, # Large log average volume (cubic feet)
HdwdFractionCT, # Proportion of hardwood chip trees (volume of hardwood divided by total volume)
HdwdFractionSLT, # Proportion of hardwood small log trees (volume of hardwood divided by total volume)
HdwdFractionLLT, # Proportion of hardwood large log trees (volume of hardwood divided by total volume)
PartialCut, # Regen/Clearcut = 0, Thin = 1
# routing info
landing_coords, # coordinate of landing ((lon, lat) tuple)
haulDist, # distance to mill (miles)
haulTime, # transit time to mill (minutes)
coord_mill # coordinate of mill ((lon, lat) tuple)
)
{
'elevation': 505.09, # feet
'harvest_cost_ft3': 0.5092, # US dollars/cubic feet
'harvest_system': 'GroundBasedMechWT', # harvest method
'haul_cost_min': 0.7604, # US dollars/minute
'haul_distance_extension': 1.051, # miles from stand landing to road
'haul_distance_ow': 31.24, # miles
'haul_time_ow': 56.7, # minutes
'landing_coordinates': (42.7, -124.3), # lon, lat
'mill_coordinates': (43.11, -124.407), # lon, lat
'skid_distance': 825.23, # feet
'slope': 22.91, # percent
'total_area': 8.52, # acres
'total_cost': 9628.0, # US dollars
'total_harvest_cost': 7990.0, # US dollars
'total_haul_cost': 1638.0, # US dollars
'total_haul_trips': 19.0, # number of trips
'total_volume': 15692.23 # cubic feet
}
-
Skidding Distance and Haul Distance Extension
Skidding distance (feet), hauling distance extension (meters), and the landing coordiantes (lon, lat (tuple)) are returned from skidding.
HaulDistExtension = HaulDistExtension*0.000189394 # convert from meter to miles -
Harvesting Cost
Harvesting cost (US dollars/cubic feet) and the name of the selected harvest system is returned from harvesting.totalHarvestCost = harvestCost*totalVolume # US dollar -
Hauling Cost
Hauling cost (US dollars/minute) is returned from hauling.
haulDist = haulDist + HaulDistExtension # miles
haulTimeRoundTrip = haulTime*2.0+HaulDistExtension*2.0/(30*60.0) # minutes
30 mph on hauling distance extensiontruckVol = percentageChipTrees*700+percentageSmallLogTrees*850+percentageLargeLogTrees*1000 # cubic feet
standard stinger-steer log truck: 700 cubic feet of small timber to 1000 cubic feet of large timbertrips = totalVolume/truckVol # adjusted upward
totalHaulCost = haulTimeRoundTrip*haulCost*trips # US dollar -
Total Costs
totalCost = totalHaulCost + totalHarvestCost # US dollar
Harvesting calculates the costs for four harvesting systems and returns the price (US dollar/cubic feet) and name of the least expensive one.
If no harvesting system is suitable due to limitations of the systems Price = NaN and HarvestingSystem = 'NoSystem' is returned.
Harvesting is based on the Fuel Reduction Cost Simulator [(FRCS-West)] (http://www.fs.fed.us/pnw/data/frcs/frcs.shtml) from the USDA.
Machine costs and labor costs are stored in [harvest_cost.xls] (forestcost/harvest_cost.xls).
from forestcost import harvesting
harvesting.harvestcost(
RemovalsCT, # Chip trees removed (trees per acre)
TreeVolCT, # Chip tree average volume (cubic feet)
RemovalsSLT, # Small log trees removed (trees per acre)
TreeVolSLT, # Small log average volume (cubic feet)
RemovalsLLT, # Large log trees removed (trees per acre)
TreeVolLLT, # Large log average volume (cubic feet)
HdwdFractionCT, # Proportion of hardwood chip trees (volume of hardwood divided by total volume)
HdwdFractionSLT, # Proportion of hardwood small log trees (volume of hardwood divided by total volume)
HdwdFractionLLT, # Proportion of hardwood large log trees (volume of hardwood divided by total volume)
PartialCut, # Regen/Clearcut = 0, Thin = 1
)
Price, # US dollars/cubic feet
HarvestingSystem, # name of harvest method
- Ground-Based Manual Whole Tree = trees are felled with chainsaws but are not limbed or bucked. Rubber-tired skidders (choker and grapple) collect and transport whole trees. Trees are chipped or processed mechanically with stroke or single-grip processors and loaded onto trucks.
GroundBasedManualWT = CostManFLBLLT2 + CostManFellST2 + CostSkidUB + CostProcess + CostChipWT + CostLoad
System limits: Slope<40 and TreeVolCT<80 and TreeVolSLT<80 and TreeVolLLT<500 and TreeVolALT<500 and TreeVol<500
- Ground-Based Mechanized Whole Tree = trees are felled and bunched; drive-to-tree machines are assumed for flat ground, whereas swingboom and self-leveling versions are included for steeper terrain. Rubber-tired grapple skidders transport bunches to the landing. Trees are chipped or processed mechanically with stroke or single-grip processors and loaded onto trucks.
GroundBasedMechWT = CostFellBunch+CostManFLBLLT+CostSkidBun+CostProcess+CostChipWT+CostLoad
System limits: Slope<40 and TreeVolCT<80 and TreeVolSLT<80 and TreeVolLLT<250 and TreeVolALT<250 and TreeVol<250
- Cable Manual Whole Tree = trees are felled with chainsaws, but are not limbed or bucked. (Trees too large to be yarded in one piece or too large to be mechanically processed at the landing are limbed and bucked in the woods.) Cable yarders transport the trees to the landing for chipping or mechanical processing and loading onto trucks.
CableManualWT = CostManFLBLLT2 + CostManFellST2 + CostYardUB + CostProcess + CostChipWT + CostLoad
System limits: SkidDist<1300 and TreeVolCT<80 and TreeVolSLT<80 and TreeVolLLT<500 and TreeVolALT<500 and TreeVol<500
- Helicopter Manual Whole Tree = trees are felled with chainsaws, and are limbed, and bucked at the stump. The helicopters then transport the logs out of the stand. Logs to be hauled in log form are loaded onto trucks, and those to be chipped are processed through a disk chipper and blown into chip vans.
HelicopterManualWT = CostManFLB + CostHeliYardML + CostChipWT + CostHeliLoadML
System limits: TreeVolCT<80 and TreeVolALT<250 and SkidDist<10000 and TreeVol<250 and TreeVolLLT<150
Hauling returns the cost (US dollar/min) to operate a standard stinger-steer log truck (18 tires).
Harvesting is based on the [Log Truck Haul Cost] (http://www.fs.usda.gov/detail/r6/landmanagement/resourcemanagement/?cid=fsbdev2_027048) from the USDA.
Machine costs and labor costs are stored in [haul_cost.xls] (forestcost/haul_cost.xls).
from forestcost import hauling
hauling.haulcost(
TravelDistanceOneWay, # One way distance from landing to the mill (miles)
TimeRoundTrip, # Round trip time from landing to the mill and back (minutes)
)
AverageCPmin # Average owning, operating, and labor cost for log truck (US dollars/ minutes)
Skidding returns the skidding distance from the centroid of the stand to the stand landing, the coordinates of the stand landing, and the distance from the stand landing to the road landing.
- A straight line from the centroid of the stand to the road landing is created.
- Where the line intersects with the stand is the stand landing.
- Distance from the centroid to the stand landing is the skidding distance and distance from the stand landing to the road landing is the haul distance extension and considered as road.
- Skidding distance limit is 1,300 feet (additional skidding distance is added to haul distance extension). If the skidding distance > 1,300 and the slope > 40 then the limit is 10,000 feet (helicopter logging).
Overall there are four possibilities how the skidding distance can be determined:
| Option 1 | Option 2 | Option 3 | Option 4 --- | --- | --- | --- | --- | --- Input Slope | 20 % | 20 % | 50 % | 50 % Input Skid Dist | 1000ft | 2000ft | 2000ft | 20000ft Adjusted Skid Dist | - | 1300ft | - | 10000ft Haul Dist Extension | - | 700ft | - | 10000ft
from forestcost import skidding
skidding.skidding(
stand_wkt, # Well-Known Text geometry of stand polygon
landing_coords, # coordinate of road landing from landing.py
Slope # Slope (%)
)
YardDist, # Skidding distance (feet)
HaulDistExtension, # Haul distance extension (feet)
coord_landing_stand_tuple # coordinate of stand landing ((lon, lat) tuple)
The area function returns the total area (acers) of the stand.
from forestcost import gis
gis.area(
lyr # OGR layer of stand
)
area # area of stand (acres)
The zonal statistics function returns the mean values of the slope and elevation raster within the zones of the stand.
from forestcost import gis
gis.zonal_stats(
input_value_raster, # Value raster of slope/elevation
lyr # OGR layer of stand
)
mean # Mean values of the slope/elevation raster within the zones of the stand
Landing returns the road landing coordinates on the closest road to the property (stand landing coordinates are determined with skidding.py).
- Centroids of all stands are created
- Centroid of all centroids is created (center of property)
- OpenStreetMap with [OSRM Routing API] (https://github.com/DennisOSRM/Project-OSRM/wiki) is used to find the nearest point on a street which is the road landing. Only roads of OpenStreetMap are considered as roads.
from forestcost import landing
landing.landing(
lyr # OGR layer of property
)
landing_coords # coordinate of road landing ((lon, lat) tuple)
Routing returns the one-way distance and time from the road landing to the mill and the coordinates of the selected mill.
OpenStreetMap with [OSRM Routing API] (https://github.com/DennisOSRM/Project-OSRM/wiki) is used to determine the distance and time.
Routing either automatically determines the closest mill or the exact mill location can be specified.
If routing determines the closest mill automatically, exponentially expanding bounding boxes around the landing are created until at least three mills are found.
If three mills are found the routes for each one are determined and the shortest one is selected.
from forestcost import routing
mill_shp = 'Data//mills.shp' # shapefile containing mill points
landing_coords = (-118.620, 44.911) # coordinates of road landing ((lon, lat) tuple)
routing.routing(
landing_coords,
mill_shp=mill_shp
)
Alternatively the exact mill location can be specified.
mill_coords = (-119.250, 44.429) # coordinates of selected mill ((lon, lat) tuple)
landing_coords = (-118.620, 44.911) # coordinates of road landing ((lon, lat) tuple)
routing.routing(
landing_coords,
mill_coords=mill_coords,
)
Additionally the mill shapefile can be filtered using OGR SQL queries
mill_shp = 'Data//mills.shp' # shapefile containing mill points
landing_coords = (-118.620, 44.911) # coordinates of road landing ((lon, lat) tuple)
mill_filter = "CITY = 'John Day'" # filter using OGR SQL query
routing.routing(
landing_coords,
mill_shp=mill_shp,
mill_filter=mill_filter,
)
total_distance, # one-way distance from road landing to mill (miles)
total_time, # one-way time from road landing to mill (minutes)
coord_mill_tuple # coordinates of selected mill ((lon, lat) tuple)