Write a lot on the essay questions (not so much that you're just BSing because they'll now that too). If they don't state specifically how many reasons to give to explain some sort of article or concept, just go as in depth as possible. Some of the ecology questions from previous nats tests have had rubrics that give 1 point per each part of an explanation to up to like 3 points. So you might think you fully explained the answer but have only explained one part and gotten less than the maximum amount of points. And read the questions more the once and make sure you answer everything they ask for. Double check your calculations and all of your answers if time allows; ecology tests at nats tend to be rather small in length and small mistakes can really kill you (I know this first hand).
It can't hurt to study really in depth, but the national ecology tests always seem to be more about understanding basic ecological principles and being able to apply them to explain why something occurs in nature.
Events: Ecology, Herpetology, Cell Bio, Entomology, Sounds of Music, Circuit Lab, Chem Lab, Disease Detective, Dynamic Planet, Five Star, EggONaut, Enviro Chemistry, Fermi, Quantum Quandaries!
Nationals: Wichita: Ecology-4, Entomology-5, Team-11; DC: Sounds-1, Team-11