Holiday caRd 2013

A holiday pResent made of competition from the EEB & Flow :-)

(Easy to copy and run if you choose "view raw" in the lower right hand corner. Just copy and paste into R, it will do all the work. You will need to download and install R if you don't already have it.)

	##Two species in a Beverton-Holt competition model on a 2-d landscape
	##################
	###Parameters
	years=15
	scape=100
	#species GR
	Sp1=50
	Sp2=40
	#landscape
	sp1_land<-array(runif(scape*scape,70,90),c(scape,scape,(years+1)))
	sp2_land<-array(runif(scape*scape,70,90),c(scape,scape,(years+1)))
	y1<-matrix(c(rep(c(rep(0.4,40),rep(0.70,20),c(rep(0.4,40))),40),rep(0.7,20*scape),rep(c(rep(0.4,40),rep(0.7,20),c(rep(0.4,40))),40)),ncol=scape,nrow=scape)
	y2<-1-y1
	res<-matrix((sp2_land[,,1]-sp1_land[,,1]),scape,scape)
	###Functions
	colrs<-colorRampPalette(sample(c("darkred","green3"),2,replace=FALSE))
	bevertonholt2sp<-function(years,scape,sp1_land,sp2_land,res){
	for(i in 1:years){
	for(j in 1:scape){
	for(k in 1:scape){
	N1<-sp1_land[j,k,i]
	N2<-sp2_land[j,k,i]
	#growth rates
	dN1<-N1*rnorm(1,Sp1,0.015)/(1+(y1[j,k]*N2+N1))
	dN2<-N2*rnorm(1,Sp2,0.015)/(1+(y2[j,k]*N1+N2))
	#update pop sizes
	sp1_land[j,k,i+1]<-N1+dN1
	sp2_land[j,k,i+1]<-N2+dN2
	#pop size differences
	res[j,k]<-(sp2_land[j,k,i+1]-sp1_land[j,k,i+1])
	}
	}
	image(res,col=colrs(6),xaxt="n",yaxt="n",add=TRUE)
	}
	}
	par(bg="wheat1",bty="n",pty="m",ps=15)
	image(res,col=colrs(6),xaxt="n",yaxt="n",lty="blank")
	bevertonholt2sp(years,scape,sp1_land,sp2_land,res)
	polygon(x=c(0.04,0.15,0.37,0.36,0.25,0.04),y=c(0.75,0.98,0.85,0.68,0.61,0.75),col="oldlace",border="darkgrey")
	lines(x=c(0.36,0.4),y=c(0.68,0.6),lwd=0.75,col="brown3")
	text(x=0.21,y=0.8,"Happy\n Holidays\n from the\n EEB & Flow",cex=1,col=colrs(6)[6],font=4,srt=-30)

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