| Air Method | VDYP calculation method which uses crown closure to calculate volumes. This method has been approved for operational use. |
| BA | Basal Area - Total cross sectional area of all living trees measured outside bark at breast height measured in square metres per hectare (m2/ha) |
| Breakage | Soundwood losses due to felling and yarding breakage; not merchantable because the broken pieces are considered too small. |
| Breast Height | 1.3 meters above the ground on the uphill side of the tree. |
| BHA | Breast Height Age - Average age (ring count) of the top height trees at breast height. |
| Calculation Method | VDYP is designed to produce volumes using one of two measures of density: the air method, and the ground method. Only the Air method is currently supported by WinVDYP. |
| CC | Crown Closure - The percentage of the ground covered by tree crowns as assessed from aerial photos (i.e. vertical projection) |
| Culmination Age | The age, in years, at which maximal mean annual increment occurs. |
| Culmination MAI | Maximum mean annual increment in stand volume measured in cubic meters per hectare (m3/ha). |
| Decay | Soundwood losses due to physical and chemical processes caused by wood-rotting fungi. |
| Diameter | VDYP estimates quadratic mean stand diameter measured outside the bark at breast height. That is, the diameter of the tree of average basal area. |
| Even-aged | A forest stand in which a relatively small age difference (10 to 20 years) exist between individual trees, in contrast to uneven-aged stands. |
| FIZ | Forest Inventory Zone - Geographical zones developed to provide a broadly based ecological classification of the forest land in British Columbia. See Appendix J for a FIZ map. |
| Gross Volume | Total standing volume (inside bark) of trees above the diameter limit, including stumps and tops measured in m3/ha. e.g. Gross volume 7.5cm+ is the volume (ib) if trees >= 7.5cm DBH |
| Ground Method | VDYP calculation method which uses basal area to calculate volumes. This method has not been approved for operational use. |
| ib | Inside Bark - With reference to measurements recorded inside the bark. |
| ITG | Inventory Type Groups - Designation of species composition by one of 42 type groups, each being a unique combination of pure or mixed species. Please see the .FIP File Data Dictionary reference found in the References section. |
| MAI | Mean Annual Increment - The average annual increase in stand volume at a particular age. This value is measured in m3/ha. |
| Natural | Refers to a stand that regenerates naturally after a disturbance such as logging or a fire. |
| ob | Outside Bark - With reference to measurements recorded outside the bark. |
| PSYU | Public Sustained Yield Unit - Areas of land, usually a natural topographic unit determined by drainage areas. |
| SI | Site Index - Top height in meters at Breast Height Age 50. Used as a measure of site productivity. |
| Species | A one or two letter code describing a particular commercial tree species. There are 27 different species codes and 5 genus code options in VDYP. |
| Species Percent | Percentage of the stand that the corresponding species occupies. Tree species percentage is based on relative gross volume above a specified diameter limit. |
| Stocking Class | A code indicating the degree if stocking, based on leading commercial species, stand age and/or diameter and number of stems per hectare. Please see the .FIP File Data Dictionary reference found in the References section. |
| TSA | Timber Supply Area - Areas of the province created by the Ministry of Forests for the purposes of analysis, planning and management of timber resources. |
| TIPSY | Table Interpolation Program for Stand Yields - A database and graphical user interface supported by MoF, Research Branch and used primarily for generating managed stand yield tables. |
| Top Height | Average height in meters of the 100 trees/ha of largest diameter at breast height. |
| Total Age | Years since germination. Usually used with reference to stands of natural origin. |
| VAF | Volume Adjustment Factor - A volume multiplier that will increase or decrease stand volumes (e.g. a value of 0.5 will halve all volumes). |
| W2B Factors | Flat factors, derived by PSYU, to account for both Waste2 and Breakage for individual tree species. |
| Waste2 | Soundwood portion of a tree or log which has more than 50% decay. Considered to be non-recoverable under current utilization standards |
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