Landscape

Commands to load and display a real landscape

## Set briskaR working intern projection to LAMBERT 93 (default)
briskaRSetInternProjection(LAMBERT_93)

## load the maize_65 data set incorporated in briskaR
## in which polygons are either maize or non-maize fields
data(maize_65)

## then, randomly assign the GMO and non-GMO marks to maize fields
## non-maize fields being considered as receptors
initial_types=maize_65@thelandscape@data
nb_maize=sum(initial_types[,1])
nb_non_maize=sum(initial_types[,2])
types=as.data.frame(cbind(0,NA,initial_types[,2]))
names(types)=c("sources","neutral","receptors")
GM_fields=sample((1:nrow(types))[initial_types[,1]==1],
0.4*(nb_maize+nb_non_maize),replace=FALSE)
types[GM_fields,1]=1
types[,2]=1*(types[,1]==0 & types[,3]==0)

## generate land1 with the new marks for polygons
land1=maize_65
land1@thelandscape@data=types

## transform receptors at the border of the study domain
## into neutral cells
border_size=200
for(i in 1:land1@n){
  if(land1@thelandscape@data[i,3]==1){
    x0=land1@thelandscape@polygons[[i]]@Polygons[[1]]@coords
    if(sum(x0[,1]<land1@xmin+border_size | x0[,1]>land1@xmax-border_size |
      x0[,2]<land1@ymin+border_size | x0[,2]>land1@ymax-border_size)>0){
      land1@thelandscape@data[i,3]=0
      land1@thelandscape@data[i,2]=1
    }
  }
}
## display the landscape
plot(land1)

Commands to generate and display a simulated landscape:

## generate the Voronoi tesselation
land=simulateInitialPartition(n=200, prop=0.4, range=10,
xmin=0, xmax=5000, ymin=0, ymax=5000)
## generate receptors at the borders of Voronoi cells
land2=simulateThickMargins(land, border_size=200, prob=0.5,
mean_thickness=5, v_thickness=50)
## display the landscape
plot(land2)

Individuals

Commands to generate and display exposed individuals for the real landscape land1:

## tuning parameters and variables
nb_ind=100 ; time_min=1 ; time_max=61
birth_dates=sample(time_min:time_max, size=nb_ind, replace=TRUE)
life_expectancies=rep(20, nb_ind)
toxic_gap=rep(15, nb_ind)
## generate exposed individuals
ind=simulateIndividuals(land1, n=nb_ind, mintime=time_min,
                        maxtime=time_max, dob=birth_dates,
            life_duration=life_expectancies, toxic_threshold=toxic_gap)
## plot individuals in the landscape
plot(land1,ind)

Toxic Intensity

Commands to compute the spatio–temporal quantities of GM pollen present on host plant leaves across the real landscape land1 and the study period:

## generate emission functions for every sources
list_sources=getSPSources(land1)
emitted_pollen=create.pollen.sources(length(list_sources),time_max)
emitted_pollen=data.frame(t=emitted_pollen,
row.names=row.names(list_sources))
## load precipitation data and restrict them to June and July 2013
data(Precipitation)
precip=Precipitation$RR[Precipitation$AN==2013 & (Precipitation$MOIS==6 | Precipitation$MOIS==7)]
plot(1:61, precip, pch=19, xlab="Day", ylab="Rainfall intensity (in mm)")

## compute concentration of pollen across space and time
tox=toxicIntensity(objectL=land1, toxic_emission=emitted_pollen,
                mintime=time_min, maxtime=time_max, size_raster=2^10,
            alpha=list(minalpha=0.1, maxalpha=0.95, covariate_threshold=30,
                                          simulate=FALSE, covariate=precip))
## display concentration of pollen at day 61
plot(x=land1, time=61, objectT=tox)

EcoToxicological

Commands to compute and display the internal concentration of Bt toxin and its impact for every host:

ind_impact=ecoToxic(land1, ind, tox, time_min, time_max,kin=4.19e-7, kout=0.1, deltat=0.1)

Displaying the cumulative impact of the Bt toxin at time 61 can be done as follows:

#plot(x=land1, y=ind_impact, time=30, objectT=tox)
plot(x=land1, y=ind_impact, time=time_max, objectT=tox)

plot(maize.landscape,maize.individuals,time=61,objectT=tox)

The histogram of maximum internal concentration is obtained as follows:

temp=apply(ind_impact@intern_toxic,1,max)
hist(temp, main="Real landscape", xlab="Maximum internal concentration",
breaks=seq(0,max(temp)+5,5))
abline(v=15,col=3)

Displaying the time series of environmental and internal concentration of toxins can be done as follows:

ID=21
plot(x=land1, y=ind_impact, objectT=tox, numind=ID)