# Using the CVRE criterion
doubs.mrt.cvre <- mvpart(as.matrix(spe.hel)~., env, 
                 legend=FALSE, margin=0.01, cp=0,xv="pick", 
                 xval=nrow(spe.hel), xvmult=100,which=4)

# Choosing ourself the best number of partitions
doubs.mrt.4 <- mvpart(as.matrix(spe.hel)~., env, 
              legend=FALSE, margin=0.01, cp=0, xv="pick", 
              xval=nrow(spe.hel), xvmult=100,which=4)