I am currently working with biofilms obtained from a brevery enviroment. When analyzing my data with the collect.single or rarefaction.single command i observed an constant Shannon-Index even at a small sample size with low evenness values. So far nothing to be worry about. Next i was curious about the proportion of richness and evenness on the Shannon-Index at the different sample sizes. Itried to use the SHE analysis method based on Buzas and Hayek which uses the formula:
H(Shannon)= lnE + lnS
I compared the sum of the lnE- and lnS-values with the Shannon-Index obtained by mothur and found that they differ. For example i obtained 48 OTUÂ´s and E=0,3361. The Shannon-Index calculated by mothur is 1,3301 but my calculation with the formula above is 2,78. Do you have any experience with this?
Thanks in advance