I would like to start a monitoring in different caves, compare caves of different age and length, and find out if there are any correlations between these factors and their diversity.
I was thinking to use the Shannon-Wiener diversity index and to use both pitfall traps and timed area search sampling methods. Can I get a single index value for each cave even if the methods are different?
And what about that caves which have stream or pools where the fauna can be very abundant? Even if I collect a sample of water, the abundance of certain species can be very high (e.g. copepoda).
Sorry for the banal questions but I have not experience with indices and statistics.
Clarification after comments:
I have about 20 caves to sample, I want to compare the fauna of these caves (richness and abundance). As I told they have differents lenghts, ages and others environmental features. Some of the caves have also streams or little pools (where I will take water samples to identify the fauna).
I have read some articles where the diversity indices were calculated using just one single methodology (traps or timed area search), and also for only one kind of fauna (acquatic or terrestrial).
The question is: Is there any methodology to get one single value of diversity index for each cave? (which considers both terrestrial and aquatic fauna). Or maybe in these conditions I can just get the number of species for each cave, without being able to compare their abundance?