Subject: Western Volume Equations, Misc. Bugs
Name: R. Havis
Date: February 11, 2016
Variants affected: Western Variants (AK, BM, CA, CI, CR, EC, EM, IE, KT,
                                    NC, OC, OP, PN, SO, TT, UT, WC, and WS)

Description:

1) All western variants: The National Volume Estimator Library (NVEL) contains the
                         volume estimators used by the Forest Service and is maintained
                         by the Forest Products Measurement staff at the Forest
                         Management Service Center in Fort Collins, Colorado.
                         FVS gets its default volume equations from the NVEL.
                         The complete list of NVEL equations for each western
                         Region has been made available to the FVS variants in 
                         each region through the VOLEQNUM keyword.

2) Region 9 variants:    in 2009, the Gevorkiantz volume calculation method was superseded
                         by the Clark method in Region 9, but was retained
                         as option 5 in field 8 of the BFVOLUME and VOLUME
                         keywords. The older FVS Gevorkiantz code has been replaced by the
                         National Volume Library Estimator code. There may be differences
                         volume calculations by this method using the newer NVEL code.
                         The Gevorkiantz board foot equations were not working.
                         This has been corrected. The dependency of the Gevorkiantz
                         board foot tables on the National Forest has been added (see
                         volume equation documentation on the Forest Products 
                         Measurements Staff web site (http://www.fs.fed.us/fmsc
                         /measure/volume/nvel/index.php).

3) Region 8 and 9 variants: The default stump height was set to 1 foot for all products.
                            This has been changed to 0.5 foot for calculations of Merch.
                            cubic foot volumes. 


2) AK and CR variants: The end-of-cycle DBH is used to calculate bark ratios
                       for the purpose of volume estimation. The AK and CR 
                       variants were using the beginning-of-cycle DBH to calculate
                       bark ratios rather than the enc-of-cycle DBH. This has
                       been corrected.
                       
3) CR and NC variants: Some variants allow changing default volume equations
                       by specifying method 8 in field 7 of the VOLUME or
                       BFVOLUME keywords. When only the VOLUME keyword was
                       used in the CR and NC variants, there was a problem
                       in the default board foot volume calculations. This
                       has been corrected.

4) LS and NE variants: The equation for yellow birch was updated.

5) OC and OP variants: Trees having DBH of less than or equal to 0.1 inches were
                       were assigned small volumes in these variants, but are now
                       assigned zero volume.


Impact on users: The list of volume equations available for selection in FVS has
                 been increased in the western variants. Users of the AK, and
                 CR variants will see slight changes in volumes, and LS and
                 NE variant users will see very slight changes in volumes
                 if there is yellow birch in their stand. Small changes in volume
                 estimates can be expected in the OC and OP variants because
                 trees with less than or equal to 0.1 inches are assigned zero volume.
                 The Merch. volumes of truncated trees will be slightly higher (on the order
                 of 0.1 cf) in Regions 8 and 9 because the change in default stump heights.
                 Volumes calculated using the Gevorkiantz method in Region 9 may
                 be different.

Files:
