R: Implementation of a two-pool C14 model with feedback...

TwopFeedbackModel14 {SoilR}

R Documentation

Implementation of a two-pool C14 model with feedback structure

Description

This function creates a model for two pools connected with feedback. It is a wrapper for the more general function GeneralModel_14 that can handle an arbitrary number of pools.

Usage

TwopFeedbackModel14(
  t,
  ks,
  C0,
  F0_Delta14C,
  In,
  a21,
  a12,
  xi = 1,
  inputFc,
  lambda = -0.0001209681,
  lag = 0,
  solver = deSolve.lsoda.wrapper,
  pass = FALSE
)

Arguments

`t`	A vector containing the points in time where the solution is sought. It must be specified within the same period for which the Delta 14 C of the atmosphere is provided. The default period in the provided dataset `C14Atm_NH` is 1900-2010.
`ks`	A vector of length 2 containing the decomposition rates for the 2 pools.
`C0`	A vector of length 2 containing the initial amount of carbon for the 2 pools.
`F0_Delta14C`	A vector of length 2 containing the initial amount of the radiocarbon fraction for the 2 pools as Delta14C values in per mil.
`In`	A scalar or a data.frame object specifying the amount of litter inputs by time.
`a21`	A scalar with the value of the transfer rate from pool 1 to pool 2.
`a12`	A scalar with the value of the transfer rate from pool 2 to pool 1.
`xi`	A scalar or a data.frame specifying the external (environmental and/or edaphic) effects on decomposition rates.
`inputFc`	A Data Frame object containing values of atmospheric Delta14C per time. First column must be time values, second column must be Delta14C values in per mil.
`lambda`	Radioactive decay constant. By default lambda=-0.0001209681 y^-1 . This has the side effect that all your time related data are treated as if the time unit was year.
`lag`	A positive integer representing a time lag for radiocarbon to enter the system.
`solver`	A function that solves the system of ODEs. This can be `euler` or `deSolve.lsoda.wrapper` or any other user provided function with the same interface.
`pass`	Forces the constructor to create the model even if it is invalid

Value

A Model Object that can be further queried

Examples

years=seq(1901,2009,by=0.5)
LitterInput=700 

Ex=TwopFeedbackModel14(t=years,ks=c(k1=1/2.8, k2=1/35),C0=c(200,5000), 
F0_Delta14C=c(0,0),In=LitterInput, a21=0.1,a12=0.01,inputFc=C14Atm_NH)
R14m=getF14R(Ex)
C14m=getF14C(Ex)
C14t=getF14(Ex)

par(mfrow=c(2,1))
plot(C14Atm_NH,type="l",xlab="Year",ylab="Delta 14C (per mil)",xlim=c(1940,2010)) 
lines(years, C14t[,1], col=4)
lines(years, C14t[,2],col=4,lwd=2)
legend("topright",c("Delta 14C Atmosphere", "Delta 14C pool 1", "Delta 14C pool 2"),
lty=c(1,1,1),col=c(1,4,4),lwd=c(1,1,2),bty="n")

plot(C14Atm_NH,type="l",xlab="Year",ylab="Delta 14C (per mil)",xlim=c(1940,2010)) 
lines(years,C14m,col=4)
lines(years,R14m,col=2)
legend("topright",c("Delta 14C Atmosphere","Delta 14C SOM", "Delta 14C Respired"),
lty=c(1,1,1), col=c(1,4,2),bty="n")
par(mfrow=c(1,1))