Q |
How does WinVDYP7 project yields? |
A |
WinVDYP7 grows stand attributes by applying growth functions to BA and QMD, and Lorey height. The growth data is then applied to the static yields to reflect change in the attributes. An associated stand level decay model is applied to obtain net merchantable volumes.
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A |
Depending on user inputs, WinVDYP7 can predict stand yields for mixed or pure species. A number of the estimated stand attributes can be adjusted to modify model predictions. It can also be used to estimate stand BA, TPH, and QMD. It can also estimate yields in stands where dramatic changes have occurred such as when selective harvesting occurs or epidemic mortality reduces live tree BA and live trees per hectare.
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Q |
What are WinVDYP7’s limitations? |
A |
Although WinVDYP7 is a growth model it currently does not model changes in species composition or succession. It requires a stronger technical background to run versus VDYP 6. |
A |
WinVDYP7is an interactive interface of VDYP7. It allows users to test scenarios and learn how VDYP 7 yield tables are generated. |
Q |
How do WinVDYP7 volume predictions compare to VDYP6? |
A |
Generally speaking, for stands of average density, at a given height the initial volume estimate for both models should be quite similar. However, due to the insensitivity of crown closure to changes in density, VDYP6 predictions will tend to remain close to the average value. VDYP7 predictions, which use BA as an input, should more closely approximate actual volumes across the density range. Projected volume trends will also differ between the two models. With VDYP7, the volume trend is affected by change in Lorey height and BA over time. With VDYP6, crown closure is held static over the projection and volume increase depends strongly on height growth. Thus VDYP7 volume projections are more likely to fall in the long term since the Lorey height of the stand tends to flatten and BA may also decline in old stands. The new stand level decay model used in VDYP7 tends to increase the deduction for decay as stands get older. |
Q |
How do WinVDYP7 predictions change by BEC Zone? |
A |
The BA increment model in VDYP7 was calibrated for coastal versus interior BEC zones due to the restrictions of the available permanent sample plot (PSP) measurement data. Much less aggregation was required when the yield functions were fitted and as a result predictions will vary between BEC zones. |
Q |
What effect does stocking class have on WinVDYP7 predictions? |
A |
No effect. WinVDYP7 does not use stocking class and it is no longer carried in VRI standard inventories. |
Q |
Can I localize WinVDYP7 for my conditions? |
A |
Yes. Provision has been made to adjust a number of the model predictions in the Additional Stand Attributes window. |
Q |
Will WinVDYP7 project from my ground measured volume? |
A |
Yes. If a ground measured volume is entered in the Additional Stand Attributes window the model will start the projection with the supplied volume. |
