The logic of Niche is largely based on code tables. They convert values (eg mlw, ...) to another (eg soil_mlw_class). For categorical data, this happens directly. For continuous data such as nitrogren or mhw, minimum and maximum values are used.
interpretation of minimum and maximum values
soil_name msw_min msw_max nitrogen_mineralisation K1 -5000 5 50 K1 5 10 55 K1 10 15 76
Niche will use the values from the _max column to determine to which category a value has to be added. In this particular case, with a soil_code of 10000 an MSW values ]5,10] will give the value 55: the upper limit is included, the lower limit is not. A value of msw=5 will give nitrogen_mineralisation=50 as a result, a value of msw10 will lead to nitrogen_mineralisation=55. When using real values for mxw, the values will be rounded up to 2 decimals. Eg 50.005 will become 50.01 (> 50) and 50.004 will become 50.00 (=50).
By default the codetables of the niche_vlaanderen package are used, but the user can supply one or more own codetables (see cli, full example at page bottom; see here<niche> for interactive implementation). If real values are used in these codetables, the decimal separator is '.' (note that no real values are used in the existing codetables).
The table soil_codes.csv contains the supported soil_codes in NICHE and their corresponding soil_group (used in determining the soil_glg_class, soil_glg_class).
The table management.csv contains the supported management_codes in NICHE. It also contains a column influence which is used in the calculation of nutrient level.
The table niche_vegetation.csv contains the link between the vegetation types that can be predicted by niche and the location factors that govern them.
- Required columns are:
- veg_code: vegetation code
- veg_type: the vegetation name
- soil_code: soil code, must correspond to the
soil_code:. - nutrient_level
- acidity
- mhw_min, mhw_max:
- mlw_min, mlw_max:
- management
- inundation
Other columns can exist but are ignored.
The lower and upper limits of mhw and mlw are included when classifying.
interpretation of minimum and maximum values
veg_code veg_type soil_name nutrient_level acidity mhw_min mhw_max mlw_min mlw_max 1 Sphagno-Betuletum KV 2 1 20 1 38 20
In the above case, mhw values 20 and 1 both fullfill the required range.