The general way is to use the points()
methods, as in
points(vare.dca, display = "sites", col = "red")
or use the text()
method if you want the site/sample labels.
orditorp()
can also be used, just change the argument to display = "sites"
, which you could have ascertained by reading ?orditorp
.
There are a number of other options, most notably ordipointlabel()
which will work harder to stop overlap of various labels.
I've written a number of blog posts on these functions in vegan, which you can consult for more explanation and examples