Calibration of root distribution

The function spwb_ldrCalibration calibrates the species root distribution within spwb, given the arguments x, meteo, psi_crit, obs and calibVar. This calibration is based on reference measured values. These reference measured values can be Soil water content, Total tranpiration or Transpiration by cohort. Return the calibrated root distribution for each tree species (no shrub calibration is done), expressed as parameters of the function root_ldrDistribution.

spwb_ldrCalibration(
  x,
  meteo,
  calibVar,
  obs,
  RZmin = 301,
  RZmax = 4000,
  V1min = 0.01,
  V1max = 0.94,
  resolution = 20,
  heat_stop = 0,
  transformation = "identity",
  verbose = FALSE
)

Arguments

x

An object of class spwbInput.

meteo

A data frame with daily meteorological data series.

calibVar

A character string indicating the calibration variable to be used. It can be one of the following: SWC, Eplanttot or Cohorts.

obs

Measured calibration variable. Depending on the value of calibVar it can be a numeric vector with the measured SWC values (if calibVar = "SWC"), or a data frame with the first column containing the measured total transpiration (named Eplanttot) and the following columns containing the cohorts transpiration.

RZmin

The minimum value of RZ (the rooting depth) to be explored (in mm)

RZmax

The maximum value of RZ (the rooting depth) to be explored (in mm)

V1min

The minimum value of V1 (the root proportion in the first soil layer) to be explored

V1max

The maximum value of V1 (the root proportion in the first soil layer) to be explored

resolution

An integer defining the number of values to obtain by discretization of the root parameters RZ and V1. The number of parameter combinations and therefore the computation cost increases increase with the square of resolution

heat_stop

An integer defining the number of days during to discard from the calculation of the optimal root distribution. Usefull if the soil water content initialization is not certain

transformation

Function to modify the size of Z intervals to be explored (by default, bins are equal).

verbose

A logical value. Print the internal messages of the function?

Value

The function returns a data frame containing the species index used in medfate, calibrated values for Z50, Z95 and V1 and the MAE value for that combination.

Details

This function performs three different kinds of calibration, selecting those root distribution parameters that minimize the MAE between the predicted values and the measured values provided in obs argument. If calibVar = "SWC" different V1 values are tested running spwb maintaining the total soil depth provided in x and assuming that value is also the depth containing 95 percent of the roots. If calibVar = "Eplanttot" or calibVar = 'Cohorts' different combinations of RZ and V1 values are tested for each tree cohort and the root paramters are selected based on the MAE between the total transpiration or the cohort transpiration.

See also

spwb_ldrOptimization for when no measured data is available, spwb, soil, root_ldrDistribution

Author

Víctor Granda, CREAF

Antoine Cabon, CTFC-CREAF

Miquel De Cáceres Ainsa, CREAF