Late to the discussion, but depending on your definition of bio cache and botanical cache, this seems impractical.
Earthcaches based off geology work well as geocachers, because a well planned earthcache subject will be relatively unchanged from month to month.
Bio cache: would this be based off animal habitat? Animals have a habit of moving around and keeping to their own schedule. How would this be tied to precise coordinates, unless these are limited to zoos or other contained environments?
Botanical cache: OK, a little better, most trees and plants tend not to hunt or migrate, so this could be more feasible. There's still a limit though - you'd need some guarantee of permanence. A cache based on an outcrop of flowers is going to require a lot more oversight than one based on a saguaro cactus.