Scube, a Growth Model for Interior Spruce

Current version:  2.3
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Scube is a whole-stand growth and yield model for interior spruce, developed with data from the SBS zone of British Columbia.

Spreadsheet imageA spreadsheet version runs in Microsoft Excel, LibreOffice, and OpenOffice. Use the link above to download a zip archive containing the spreadsheet, a README text file, and pdf Help. To run, unzip somewhere, and execute Scube.xls. You may have to lower macro security to Medium, and allow Enable Macros when prompted. Once the spreadsheet opens, click on HELP at the top for instructions.

The Scube spreadsheet is open-ended, in that you can use the standard tools to extend it with special-purpose entries, to produce graphs, or to customize it in other ways. Here is a simple example of carbon sequestering calculations. It is not difficult to use the Solver add-in to optimize initial density, thinnings, and harvest age, following a similar example in TADAM.

Vensim image

A very different implementation uses the boxes and arrows of System Dynamics. Here is an input file that can be loaded into the free version of Vensim. This can be useful for experimentation, and may help to better understand the structure of the model. The software can display graphs or tables for any of the variables, with inputs and parameters being changed through keyboard or graphical sliders in real-time.

Publications on the model are listed below. An extended write-up with detailed descriptions of model and methods can be downloaded. Please email garcia@unbc.ca or call +1(250) 960-5004 for any questions or comments. See also the Frequently Asked Questions (FAQ). This conference presentation may be helpful.

LobDyn is a similar model for loblolly pine in the southeastern USA. Video tutorials one and two are also applicable to Scube.

The model can also be embedded into other decision support systems. For that, one could use the Visual Basic macros from the spreadsheet, or the R functions written for parameter estimation, possibly translated to other computer language.

The software is open source (MIT license).

References:

García, O.  A simple and effective forest stand mortality model.  Mathematical and Computational Forestry and Nat.-Res. Sci. 1(1), 1-9. 2009.   Text (MCFNS).

Hu, Z. and García, O.   A height growth and site-index model for interior spruce in the Sub-Boreal Spruce biogeoclimatic zone of British ColumbiaCanadian Journal of Forest Research 40(6), 1175–1183. 2010.  doi:10.1139/X10-075

García, O.  A parsimonious dynamic stand model for interior spruce in British Columbia.  Forest Science 57 (4), 265-280. 2011. Abstract / text. Preprint.

García, O., Burkhart, H. E., and Amateis, R. L.  A biologically-consistent stand growth model for loblolly pine in the Piedmont physiographic region, USA.  Forest Ecology and Management 262(11), 2035–2041. 2011. doi: 10.1016/j.foreco.2011.08.047. Preprint.

García, O.  LINK News: Growth and yield of interior spruce: filling in the blanks.  BC Journal of Ecosystems and Management 12(3), xvi–xvii. 2011.  Text (BCJEM).

Oscar Garcia

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