So I'm designing a world where the air has its own ecosystem, separate from the one on the land, because sky whales are cool. However, I'm having trouble figuring out what the plants and other producers would use to, you know, produce.
In the ocean, you have stuff like phytoplankton, which get nutrients from stuff dissolved in the water. I don't know that that would work in the air, especially on a scale big enough to support larger animals.
On land (and also in the ocean,) you have bigger plants, like grass, trees, and kelp, which all rely on having some sort of soil or something to grow in, to get nutrients from.
My question is, where can an airborne plant or microorganism get the nutrients it needs to grow and sustain a few tiers of consumers, without having a phase of life on the ground?