Q |
What computer languages are used in different parts of VDYP7 system? |
A |
The following is brief list:
- Forest Inventory Planning file (FIP) – SAS macro
- FIP Extraction- SAS program that reads FIP files
- FIPSTART, VRISTART, VRIADJST, VDYP7 and VDYP7BACK are all written in FORTRAN.
- VDYP7 system interfaces are based on DOS commands at present.
- VDYP7 Attribute Adjustment uses MS Access tables and VDYP7 Console uses text files in .csv format.
Note: FIP files are associated with Forest Cover Inventories (FCI) that preceded the Vegetation Resource Inventory (VRI) standard.
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Q
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What are some of the technical challenges in running VDYP7? |
A |
Users should be aware of the following challenges; efforts will be made to address these challenges over time:
- Exact syntax is required to define commands to run the model. Any errors in syntax will cause execution failure.
- Error messages may be difficult to interpret and linking the errors to their input data source can be cumbersome.
- After executing a VDYP7 run, the error message log file may contain hundreds of messages some of which may be simple warnings, and others may be actual fatal errors. In some instances, a fatal error may occur without a message being generated
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Q |
How does VDYP7 deal with young stands (<30 years)? |
A |
Height values within the yield tables are generated by calls to SINDEX. SINDEX is a set of programming functions, supported by MoFR Research Branch, that encapsulate various measures of site productivity, especially site index. If the photo age is greater or equal to 30 years, then site index (SI) is derived, using the supplied age and height as inputs. Projected height in the yield table will then be derived accordingly, using the projected age and SI as inputs to SINDEX. In this case, the supplied and projected heights should always be harmonized since both will be in accordance with SINDEX relationships. When the supplied age is less than 30 years, the supplied SI is employed to determine the site heights. In this case, the SINDEX-based link between the supplied height and site height in the yield table may no longer exist, and relationships may appear disconnected. This will be most evident when the supplied age/height/SI triplet differs significantly from the relationship predicted by SINDEX. In cases when the site quality is judged too low to generate a future stand description then per hectare yields will not be generated. |
