Nlai: Leaf N distribution within canopies

In nlraa: Non-linear regression for agricultural applications

Description

Function used to describe leaf N distribution within canopies (Jonshon et al., 2010 AoB). This is equation 1.9 in Table S.1 in the paper referenced below.

Usage

Nlai(lai, Yo, nb, kn, c)

Arguments

lai	Cummulative leaf area index. Starting from the top. Should be zero right above the canopy.
Yo	Value of leaf N concentration at lai = 0
nb	Minimum N for photosynthesis
kn	extinction coefficient
c	emprical paramater: when c=0 then the there is no decay (uniform distribution), when c=1 then the decay is exponential, when c>1 then the decay takes an inverse S shape

Value

a numeric vector of length equal to the inputs

Author(s)

Fernando E. Miguez

References

Nonlinear Regression Models and Applications in Agricultural Research. Sotirios V. Archontoulis and Fernando E. Miguez. Agronomy Journal. doi: 10.2134/agronj2012.0506

Examples

require(lattice)
## Set parameter values and plot the relationship
lai  <- seq(1, 8, 0.5)
ans1 <- Nlai(lai, Yo=2, nb=0.4, kn=0.5, c=1)
ans2 <- Nlai(lai, Yo=2, nb=0.4, kn=0.5, c=4)
ans3 <- Nlai(lai, Yo=2, nb=0.4, kn=0.5, c=8)
ans4 <- Nlai(lai, Yo=2, nb=0.4, kn=0.5, c=12)
xyplot(ans1 + ans2 + ans3 + ans4~ lai, type="l",
      auto.key=TRUE, ylab = "N distribution", xlab = "LAI")

nlraa documentation built on May 2, 2019, 5 p.m.