For my study I am comparing diversity of mangrove epibiont communities among estbalished, reforested and deforested mangrove sites. In which extend can I use the comparison of Shannon-Indeces in-between sites ? How important is the environmental setting and similarity of habitats to apply the Index calculations ?
In fact, you are comparing diversity of communities between habitats, yes? I think, that you may compare Shannon's H differences - significant or not. I am using program Divord of B. Tothmeresh, however it is old and runs in DosBox under windows. However, there are R-package programs, which also include diversity ordination.
Have a look at the PAST software they have a number of different diversity comparisons http://folk.uio.no/ohammer/past/
which are explained on page 35 of the manual
http://www.uq.edu.au/dinosaurs/documents/past.pdf
Dear Mark & Linas,
thanks for the ideas, but I'm not looking for a software, rather asking a question to the theoretical background of the Index. In which extend can I use the comparison of Shannon-Indeces in-between sites with different environmental settings ? Do habitats need to be similar to a certain degree to apply and compare the Indeces?
Shannon Weiner Index can only be applied if the habitat and the community are mostly similar. You can compare between two shades of red, but you cannot compare between Red and Black
Verena,
As you read on the measure, you see that it can change depending on richness and evenness and of course this metric knows nothing about your environmental treatments. Since you are interested in comparing this measure of the assemblage between your habitat treatments, I would advice designing your study with the attempt to control the other potential variables- you want to have the same number of samples from trees, trees from plots, plots from forests, same seasons, etc., or, failing that, have enough data collected such that your community assemblage at each treatment is robust enough for comparison. I recommend instead of looking at this index, try looking at species accumulation curves. The shape of the curves between your three treatments will yield just as much insight as the index, but yields more visual information than just one number. Best of luck.
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