Real leadership is what admissions committees are looking for. They pretty much know what being President of the Ecology Club is.
Stanford is one of the most selective universities. If you took your education to heart, started making straight A’s and took the most challenging and competitive classes your school had to offer, there is a small chance you could get into the low end of the zone by application time your junior year. You would also have to find something that you are passionate about and be able to write well about it.