Species Parameterizations

A considerable number of species have been parameterized for 3-PG. The UBC 3-PG website contains a link 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 here1, while the paramterizations for major central European species can be found here2. Additionally, the authors of the r3PG package (more here) 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.

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 here3 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 here4, by Peter Sands, while additional tips for species parameterization can be found here5

Footnotes

  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↩︎

  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.↩︎