I recommend Conservation Biology. The abstract provides a VERY succinct summary of everything you say in the lab, and should probably be written last as a consequence. The introduction provides a theoretical background to what you have done. I expect you to include some references, so you will be spending some time in the library. The references should not just be those included in lab or course handouts.
Independent research is key here.
Describe how you sampled, what you did in the lab, and anything else that you have done. Organization in your write-up will be important. The results section should be intuitively clear. In addition to a short word description of your results, provide tables that shows the Shannon values, and Sorenson's values. Tell me about your statistical results, and anything else you found.