library (vegan)
simul1.spe <- read.delim ('http://www.davidzeleny.net/anadat-r/data-download/simul1-spe.txt', row.names = 1)
PCA <- rda (simul1.spe)
CA <- cca (simul1.spe)
par (mfrow = c(1,2))
ordiplot (PCA)
ordiplot (CA)

PCA.short <- rda (simul1.spe[1:50,])
CA.short <- cca (simul1.spe [1:50,])
par (mfrow = c(1,2))
ordiplot (PCA.short)
ordiplot (CA.short)