There are basically two types of statistical analysis, the first of which is purely descriptive (e.g., percentages etc.) The second is known as inferential statistics because it tests inferences in the form of hypotheses about the relationships among variables (e.g, correlations).
Can you say more about what your research questions are?
I agree with David, more information on your research questions would be helpful. If you want to look on population changes depending on environmental factors, anything from MANOVA to general linear models would work, but again, narrowing down your question would help.