No, you do not need to be worried about that warning. You have rarefaction up
to the observed community, and that is always constant, hence you get the
warning of zero standard deviation. That should be fixed, but I’m too lazy.
Contributions welcome in vegan at https://github.com/vegandevs/vegan
I am using EcoTest.sample (rareNMtests package) to compare rarefaction curves
for 19 vegetation plots on two soil types (alluvial and canyon). The code below
produces the following warning (more than 50 times): "In cor(x > 0) : the
standard deviation is zero".
The test still produces all the exp
