Published on May 11, 2007
HOW TO DO AN INVENTORY OF YOUR TREES Dick Potts Potts Tree Farm Holmes County, Ohio
Reasons for Inventory Basic Business Process: What’s in stock What’s its value What’s for sale Tree Farming: Timber management Timber sale Timber value Timber basis
How to Inventory Count them ALL - 100% inventory!
What Information is Needed? Site Soil, Slope, Orientation, Aspect, Elevation, Watershed, Site Index Trees Species, DBH, Height, Logs (16’), Quality, Acceptable Growing Stock (AGS), Unacceptable Growing Stock (UGS), Sawtimber, Pole, Sapling, Cull, Understory, Regeneration, Number of Trees Results Stocking (Chart or %), Basal Area, Board Feet (BdFt) Sawtimber, Sawtimber Value, Tons or Cords Pulp, Rings per Inch
Which Trees Are Yours? Where are your boundaries? Survey, Corners, Line Markers, Acreage
Property Map Very Useful
Inventory Methods 100% inventory High accuracy but requires time and effort 1/10 th Acre Plots 66’ square, multiply by 10 for per acre approximation 1/5 th Acre Plots 53’ radius, multiply by 5 for per acre approximation Variable Radius Plots Most widely used for speed and sufficient accuracy
Sampling Approximate Methods Require Statistical Random Sampling Location of Plots Random with no overlapping Stay away from edges and unusual areas Number of Sample Plots Depends on total area size ~10 or greater is desirable Reference: Avery and Burkhart 1994, Forest Measurements , 4 th ed., McGraw Hill, Inc., New York. Ashley 1991, Simplified Point-Sample Cruising , USDA FS, NA-UP-01-91.
Variable Radius Plot Instruments Biltmore Stick – Angle Gauge Glass Prism Penney – Angle Gauge Basal Area Factor (BAF) Most common BAF = 10 Results Basal Area = BAF X “trees IN” Stand Density Measure Reference: McEvoy, How Point Sampling Works , Forest Products EQUIPMENT, Vol. 11, No. 7, March 2003, pp. 24….
Number of Tree per Acre Count in 1/10 th or 1/5 th Acre Plots then convert to one acre Use Variable Radius Plot Data then calculate Expansion Factor for each tree and sum for number Calculation of Expansion Factor (EF) EF = BAF/(.005454 x N x D x D) for individual tree BAF = 10 N = # sample points D = DBH Example: EF = 10/(.005454 x 10 x 11 x 11) = 1.5 trees/acre Sum EF for all trees in Plot for number of trees per acre.
Stocking Chart Plot of Basal Area vs Trees per Acre
Data Analysis by Computer Create your own spreadsheet for data entry and calculations Use available software
Freeware - USFS
Freeware - USFS
Freeware - USFS Northeast, Central States, Lake States Versions
Example TWIGS Results 2004 Harvest – Clearcut 1986 Inventory Projected to 2001 10,832 BdFt/acre 1997 Inventory Projected to 2002 12,629 BdFt/acre 2002 Sale Inventory 14,167 BdFt/acre 1989 Harvest – Clearcut 1987 Inventory 12,755 BdFt/acre 1989 Inventory Koral’s data (TWIGS) 10,692 BdFt/acre 1989 Inventory Koral’s data (SILVA) 10,175 BdFt/acre
TWIGS Information and Data
TWIGS Data File Generate TWIGS data file with the program TREEGEN Switch to TREEGEN and TWIGS
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