- Some are not biologically realistic, e.g. repression is well documented
in lodgepole pine regenerating at high densities, but not at lower
densities or in other species.
- Response data are not available, e.g. fertilization trials do not
cover all species.
- A particular variable is planned for inclusion in later versions
of TIPSY, e.g. number of "free-growing" trees.
- All combinations would create an unmanageable database, e.g. commercial
thinning tables for various pre- and post-thinning densities in combination
with all available species, treatments and other options.
- Species: TIPSY's database has ten species - At, Cw, Dr, Fdc, Fdi, Hwc, Hwi, Pl, Sw, Ss. See TIPSY's online documentation for recommended substitutions.
- Initial density, pre-commercial thinning, and commercial thinning:
See TIPSY's online documentation for density (trees/ha) restrictions
at establishment, and in concert with pre-commercial and commercial
thinning.
- Fertilization: TIPSY allows any species to be treated, and
the default values incorporate the best available information.
- Genetic gain: Good information is available for coastal Douglas-fir
and to a lesser extent for all other species.
- Repression: Repression occurs with increasing intensity up
to the limit of the database (250 000 trees) in lodgepole pine stands
that regenerate naturally (random distribution) at densities in excess
of 13 825 trees/ha. This phenomenon is not available for clumped distributions
where repression is expected to be less of a problem.
- Pruning: This treatment contributes only to employment (JOBS
module) in this version of TIPSY. It does not affect the volume or
value of logs or lumber, or the economic analysis.
- Brushing: Brushing does not affect yield because we assume
it has occurred if required to achieve the potential yields reported
by TIPSY. However, the treatment does contribute to the economic analysis
and employment generation.
Can I compare TIPSY predictions to VDYP predictions?
A comparison between the uses and applications of TIPSY and
VDYP can be seen in the paper
Introduction to TIPSY and VDYP. Key differences
between VDYP and TIPSY make comparisons difficult. They are:
- Databases: VDYP uses widely scattered samples that
include the range of natural variation. TIPSY uses samples from fully-stocked,
healthy research plots.
- Input Options: TIPSY requires an initial or existing
stems/hectare. VDYP (air approach) requires an established stand Crown
Closure (comparable values must be selected to do any yield comparisons).
- Output Options: VDYP gives average yields (net
decay). TIPSY gives potential yields (gross) that must be adjusted
to reflect operational conditions.
TIPSY comes complete with a comprehensive on-line reference manual,
which includes a context sensitive Help system.
For additional information on TIPSY and growth & yield models, please
contact:
Mario Di Lucca,
Growth and Yield Applications Specialist.
For any questions regarding the installation or operation of TIPSY,
please contact:
Shelley Grout, Software
Applications Specialist
- For an introduction to TIPSY and problem solving using TIPSY click
here. - Note that the introduction and problem-solving have not been updated to reflect the latest TIPSY version.
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