No, it's not going to get reopened in this state because it's not about worldbuilding.
You are not asking how to design the ecology of your world, your asking how your going to present the description to the readers.
Definition should fit in limited space, maybe about 50 book pages of
easy to read text (should fit in an RPG book along other world
information and rules)
Only defining details that seems important to the human inhabitants
(no need to include bacteria for example)
The definition should show how the "food pyramid" works and avoid
mysteries such that how some creatures would find something to eat
given their habitat or other aspect of their definition
If that is not your question then you should edit it and just focus on the: how to create the ecosystem, which is a big topic on it's own.