Move key variables from config to a DB or Spatial

I would like the Chapman-Richards module to draw the growth variables from a SQLite database, and optionally from a Raster spatial layer, rather than being written into the config file.

The Chapman-Richards Function has four input variables:

max — asymptote – maximum peak carbon yield (Tonnes carbon per hectare);

k — parameter used in modeling tree growth, dimensionless;

age — age of the forest (years);

m — parameter used in modeling tree growth, dimensionless.

Max, k and m are currently set in the config for using this module, and in doing so limits the ability to use spatial data. Age is calculated by the module.

It would be useful if the functionality of this module was changed, such that:

• Forest type is determined from a spatial layer (Forest ID returned from a spatial layer (Vector or Raster)
• Max, k and m associated with this Forest ID is within a SQLite database that the module links to,
• That users have the option to obtain Max from a spatial layer (raster)

This will allow users to have the growth variables for multiple forest types in a DB, and when completing a spatial run, the correct variables are returned. By including a switch so that users can optionally get Max biomass from a spatial layer will greatly improve the functionality.

Start by locating the Chapman-Richards module entry point, its config handling, and the existing age and growth-variable calculation. Then review how spatial inputs are represented and how SQLite could provide Forest ID mappings. Done means supporting vector or raster Forest ID input, database-backed max/k/m values, and an optional raster source for max without requiring those values in config.