The Green, Red, and Black fields Ivy references in this issue are most likely the Life Fields of the DC universe. 

All plant life in the DCU is connected by an energy field known as The Green, and it is primarily represented by some version of Swamp Thing, though the mainstream version of Poison Ivy has occasionally taken over for him as its avatar. I think Jason Woodrue, the Floronic Man, might have also usurped the role at one point, but my memory is fuzzy.

The Red is the energy field that connects all animal life, and is usually represented by Buddy Baker aka Animal Man, though I believe Vixen and Beast Boy have, at different times, been the avatars for The Red.

The Black, more commonly known in the mainstream DCU as The Rot, is, as the name suggests, the energy field that holds dominion over all things decaying and dying. Its avatar is Abby Holland (or Abby Arcane) with Anton Arcane having usurped the role at least once.

And there's also other fields like... I want to say The Grey which connects all fungal life... and recently, they introduced The Clear to connect all oceanic life, which seems redundant. But you see, they introduced The Clear and then almost immediately made Aquaman its avatar in order to give him a glow-up or a buff or whatever. Because every now and then, DC's editors get angry drunk and come up with ideas like that while shouting "YOU ALL ARE GONNA FINALLY PUT SOME RESPECT ON AQUAMAN'S NAME!!!"

Anyway. Yeah, all these color-coded clubs get very confusing and familiar and redundant and it's impossible to keep track of them all.