medfate (version 5.1.0)

hydraulics_defoliation: Hydraulic-related defoliation

Description

Functions to calculate the proportion of crown defoliation due to hydraulic disconnection.

Usage

hydraulics_proportionDefoliationSigmoid(
  psiLeaf,
  P50,
  slope,
  criticalLeafPLC = 0.88,
  cvLeafP50 = 10
)
hydraulics_proportionDefoliationWeibull(
  psiLeaf,
  c,
  d,
  criticalLeafPLC = 0.88,
  cvLeafP50 = 10
)

Value

The proportion of crown defoliation.

Arguments

psiLeaf

Leaf water potential (in MPa).

P50, slope

Parameters of the Sigmoid function.

criticalLeafPLC

Critical leaf PLC corresponding to defoliation

cvLeafP50

Coefficient of variation (in percent) of leaf P50, to describe the variability in hydraulic vulnerability across crown leaves.

c, d

Parameters of the Weibull function.

Author

Hervé Cochard, INRAE

Miquel De Cáceres Ainsa, CREAF

Details

The functions assume that crowns are made of a population of leaves whose hydraulic vulnerability (i.e. the water potential corresponding to 50% loss of conductance) follows a Gaussian distribution centered on the input P50 and with a known coefficient of variation (cvLeafP50). The slope parameter (or the c exponent in the case of a Weibull function) is considered constant. Leaves are hydraulically disconnected, and shedded, when their embolism rate exceeds a critical value (criticalLeafPLC).

See Also

hydraulics_conductancefunctions