Section_6.qmd

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title: "Species Parameterizations"
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A considerable number of species have been parameterized for 3-PG. The UBC 3-PG website contains a [link](3pg.forestry.ubc.ca/3pg-studies/) to many papers that have used 3-PG, and includes a note on which species have been studied. For example, the paramerization for ponderosa pine (*Pinus ponderosa* Doug. ex Loud.) can be found [here](https://www.sciencedirect.com/science/article/pii/S030438000400434X)[^1], while the paramterizations for major central European species can be found [here](https://link.springer.com/article/10.1007/s10342-021-01370-3)[^2]. Additionally, the authors of the r3PG package (more [here](./section_5.qmd)) put together a database with a list of species that have been parameterized; their list can be found by using the function: `View(i_parameters_lit)` in R after loading the package.

[^1]: Coops, N. C., Waring, R. H., & Law, B. E. (2005). Assessing the past and future distribution and productivity of ponderosa pine in the Pacific Northwest using a process model, 3-PG. *Ecological Modelling*, *183*(1), 107-124.

[^2]: Forrester, D.I., Hobi, M.L., Mathys, A.S. *et al.* Calibration of the process-based model 3-PG for major central European tree species. *Eur J Forest Res* **140**, 847–868 (2021). https://doi.org/10.1007/s10342-021-01370-3

### Parameterizing Your Own Species

In some instances, a species parameterization may not exist. In this case, it is necessary to parameterize your own species:

-   If possible, parameter values should be assigned by direct measurement
-   If this is not possible, values should be assigned by analogy with another species (i.e. the two species share physiological traits)
    -   In this case, it is particularly useful to find previous parameterizations for similar species
    -   For example: if one was trying to parameterize black spruce, using parameter values for white spruce from [here](https://www.sciencedirect.com/science/article/pii/S0304380016000107)[^3] would be a great place to start
-   Parameters can be estimated by adjusting their values to optimize the fit of 3-PG outputs to observed field data
    -   It is important to base the estimates on observations of as many distinct variables as possible, with covering a a wide range of conditions
    -   For example: using plot data from trials with a known location and planting date with regular DBH measurements would be an excellent resource for tuning parameterizations
-   A thorough overview of how to address novel species parameterizations is provided [here](https://3pg.sites.olt.ubc.ca/files/2014/04/3-PG-guidelines.TR141.pdf)[^4], by Peter Sands, while additional tips for species parameterization can be found [here](https://www.sciencedirect.com/science/article/pii/S0378112701005862)[^5]

[^3]: Amichev, B. Y., Bentham, M. J., Kurz, W. A., Laroque, C. P., Kulshreshtha, S., Piwowar, J. M., & Van Rees, K. C. (2016). Carbon sequestration by white spruce shelterbelts in Saskatchewan, Canada: 3PG and CBM-CFS3 model simulations. *Ecological Modelling*, *325*, 35-46.

[^4]: Sands, P. (2004). *Adaptation of 3-PG to novel species: Guidelines for data collection and parameter assignment* (Technical Report 141; Project B4: Modelling Productivity and Wood Quality). Cooperative Research Centre for Sustainable Production Forestry, CSIRO Forestry and Forest Products. https://3pg.forestry.ubc.ca/files/2014/04/3-PG-guidelines.TR141.pdf

[^5]: Sands, P. J., & Landsberg, J. J. (2002). Parameterisation of 3-PG for plantation grown Eucalyptus globulus. *Forest Ecology and Management*, *163*(1-3), 273-292.