Optimization of rock fragment content

Function utils_rockOptimization finds optimum rock fragment content in the soil corresponding to given vegetation, weather and target percent loss of conductance (PLC), following a modification of the method proposed by Druel et al. (2023).

Usage

utils_rockOptimization(
  x,
  soil,
  SpParams,
  control,
  meteo,
  PLCquantile = 0.9,
  qPLC_target = 12,
  qPLC_tol = 0.5,
  sew_min = 30,
  max_rocks = 99,
  verbose = FALSE,
  ...
)

Arguments

x: An object of class forest.
soil: An object of class data.frame or soil, containing soil parameters per soil layer.
SpParams: A data frame with species parameters (see SpParamsDefinition and SpParamsMED).
control: A list with default control parameters (see defaultControl).
meteo: A data frame with daily meteorological data series (see spwb).
PLCquantile: Maximum PLC quantile to be calculated across years.
qPLC_target: Target PLC to be achieved (by default 12%).
qPLC_tol: Tolerance of PLC difference to target accepted when finding solution.
sew_min: Minimum soil extractable water (mm) for rock exploration.
max_rocks: Maximum content in coarse fragments allowed for any soil layer.
verbose: A logical value. Print the internal messages of the function?
...: Additional parameters to function spwb.

Value

Function utils_rockOptimization returns a list containing:

RFC: A vector with the estimated rock fragment content for each soil layer.
SEW: Soil extractable water (mm).
runs: Number of simulations performed.
message: Text message indicating whether optimization could be done (OK) or not.

Details

The function performs a model inversion based on an ecohydrological assumption, consisting in that forest leaf area index is in equilibrium with a low embolism rate under normal conditions. This is translated in that the (by default 90%) interannual quantile of the maximum annual percent loss of conductance (PLC), averaged over plant cohorts, should be close to a target PLC value (by default 12%).

The algorithm first determines the PLC corresponding to the minimum and maximum soil extractable water (SEW). The minimum SEW (SEW_min) is an input parameter, whereas the maximum SEW (SEW_max) corresponds to no rock fragments in the soil.

Then three situations are distinguished:

If PLC(SEW_min) < qPLC_target and PLC(SEW_max) < qPLC_target, the function will use uniroot to find the root of the function f(x) = PLC(x) - qPLC_target, where x is SEW, which corresponds to a factor that multiplies the original rock fragment content.
If both PLC(SEW_min) < qPLC_target and PLC(SEW_max) < qPLC_target, the function cannot find an optimum, because PLC is always too low, and will return the original rock fragment content
Analogously, if both PLC(SEW_min) > qPLC_target and PLC(SEW_max) > qPLC_target, the function cannot find an optimum, because PLC is always too large, and will return the original rock fragment content

References

Druel, A., Martins, N., Cochard, H., De Caceres, M., Delzon, S., Mencuccini, M., Torres-Ruiz, J., and Ruffault, J.: European forest vulnerability to hydraulic failure: an ecohydrological approach, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-17068, https://doi.org/10.5194/egusphere-egu23-17068, 2023.

Author

Arsène Druel, URFM-INRAE

Nicolas Martin-StPaul, URFM-INRAE

Miquel De Cáceres Ainsa, CREAF

Examples

# \donttest{
#Load example daily meteorological data
data(examplemeteo)

#Load example plot plant data
data(exampleforest)

#Default species parameterization
data(SpParamsMED)

#Initialize soil with two layers
examplesoil <- defaultSoilParams(4)

#Rock fragment content optimization (Granier)
utils_rockOptimization(exampleforest, soil = examplesoil,
                       SpParams = SpParamsMED, meteo = examplemeteo,
                       control = defaultControl("Granier"),
                       elevation = 100, latitude = 41.82592)
#> $RFC
#> [1] 59.97553 99.00000 99.00000 99.00000
#> 
#> $SEW
#> [1] 31.73415
#> 
#> $runs
#> [1] 9
#> 
#> $message
#> [1] "OK"
#> 
# }