GenerateWebs: Generates food webs with S species and L links

In foodweb: Generating food webs

Description

Generates random, cascade and niche food webs with S species and L links

Usage

generate.random (S, L)

generate.cascade (S, L) 

generate.niche (S, L, c = 1, Ctol = 0.1, toliter = 1000)

Arguments

S	The number of species in the food web
L	The number of links in the food web
Ctol	Connectance tolerance for niche model generation. Models with connectance beyond +/- Ctol of the empirical web connectance will be replaced until within tolerance. Defaults to 0.1
c	parameter for niche food web generation; If (c == 0) this reduces to generalized cascade models (see Stouffer et al. 2006); If (c == 1) this reduces to the Niche model of Williams and Martinez
toliter	The maximum number of times to try generating a model which conforms to the connectance tolerance. Defaults to 1000.

Details

Function generate.random generates a random food web with S species and L links

Function generate.cascade generates a cascade food web with S species and L links

Function generate.niche generates a generalized niche model with S species and L links. Includes a check for desired connectance

Value

a Flow matrix

Author(s)

Yangchen Lin <[e-mail]>,

Karline Soetaert <[e-mail]>,

Owen Petchey <[e-mail]>

References

Stouffer, D.B., Camacho, J., Guimer\'a, R., Ng, C.A. and L.A. Nunes Amaral, 2005 Quantitative patterns in the structure of model and empirical food webs. Ecology 86(5), 1301–1311.

Stouffer, D.B., Camacho, J. and L.A. Nunes Amaral, 2006 A robust measure of food web intervality. PNAS 103 (50), www.pnas.org/cgi/reprintframed/103/50/19015

See Also

Interval, the food web intervality index.

Benguela, the Benguela pelagic food web.

Examples

## -----------------------------------------------------------------------------
## Characteristics of the Benguela food web:
## -----------------------------------------------------------------------------
L <- 203
S <- 29

randomweb <- generate.random (S, L)

cascadeweb <- generate.cascade (S, L) 

nicheweb <- generate.niche (S, L)

# image plots
par (mfrow = c(2,2))
imageweb(randomweb,  main = "random web")
imageweb(cascadeweb, main = "cascade web") 
imageweb(nicheweb,   main = "niche web") 

BB <- (Benguela) ; BB[BB > 0] <- 1
imageweb(BB,  main = "Benguela food web") 

## -----------------------------------------------------------------------------
## Niche webs
## -----------------------------------------------------------------------------
nicheweba <- generate.niche (S, L, c = 0)
nichewebb <- generate.niche (S, L, c = 0.3)
nichewebc <- generate.niche (S, L, c = 0.6)
nichewebd <- generate.niche (S, L, c = 1.0)

par (mfrow = c(2,2))
imageweb(nicheweba, main = "niche web, c = 0") 
imageweb(nichewebb, main = "niche web, c = 0.3") 
imageweb(nichewebc, main = "niche web, c = 0.6") 
imageweb(nichewebd, main = "niche web, c = 1") 

foodweb documentation built on May 2, 2019, 5:56 p.m.