R/fW.Gompertz.R

In SoilR: Models of Soil Organic Matter Decomposition

#' Effects of moisture on decomposition rates according to the Gompertz
#' function
#' 
#' Calculates the effects of water content on decomposition rates.
#' 
#' 
#' @param theta A scalar or vector containing values of volumetric soil water
#' content.
#' @param a Empirical parameter
#' @param b Empirical parameter
#' @references I. Janssens, S. Dore, D. Epron, H. Lankreijer, N. Buchmann, B.
#' Longdoz, J. Brossaud, L. Montagnani. 2003. Climatic Influences on Seasonal
#' and Spatial Differences in Soil CO2 Efflux. In Valentini, R. (Ed.) Fluxes of
#' Carbon, Water and Energy of European Forests. pp 235-253. Springer.
fW.Gompertz<- structure(
  function 
  (theta,     
   a=0.824, 
   b=0.308 
  )
  {
  exp(-exp(a-b*theta*100))
  }
  ,
  ex=function(){
    th=seq(0,1,0.01)
    xi=fW.Gompertz(theta=th)
    plot(th,xi,type="l",main="Effects of soil water content on decomposition rates",
         xlab="Volumetric soil water content (cm3 cm-3)",ylab=expression(xi))
  }
)