scheffer {primer}

A resource-based model of alternative stable states

Description

A model of floating vs. submerged plant dominance in shallow aquatic systems, after Scheffeer et al. (2003). For use with ode in the deSolve package. Floating plants are better competitors for light, as long as submerged plants cannot drive down nitrogen levels.

Usage

scheffer(t, y, p)

Arguments

t

the time point for a realization of the integration.

y

the vector of populations, at each time t.

p

a vector or list containing the necessary parameters.

Value

Returns a list of length one which is the vector of the rates of increase (required by ode).

Author(s)

Hank Stevens <[e-mail]>

References

Scheffer, M., Szabo, S., Gragnani, A., van Nes, E.H., Rinaldi, S., Kautsky, N., Norberg, J., Roijackers, R.M.M. and Franken, R.J.M. (2003) Floating plant dominance as a stable state. Proceeding of the National Academy of Sciences, U.S.A., 100, 4040–4045.

Stevens, M.H.H. (2009) A Primer of Ecology with R. Use R! Series. Springer.

See Also

lvcompg, igp

Examples

p <- c(N=2.5, as=0.01, af=0.01, b=0.02, qs=0.075, qf=0.005,
       hs=0, hf=0.2, ls=0.05, lf=0.05, rs=0.5, rf=0.5, W=0)
t <- 1:200
Initial <- c(F=10, S=10)
S.out1 <- ode(Initial, t, scheffer, p)
matplot(t, S.out1[,-1], type='l')
legend('right', c("F", "S"), lty=1:2, col=1:2, bty='n')