What are pioneer species?

Pioneer species are species that arrive first in a new environment that was created.

Explanation:

Species that come first in a newly created environment are called pioneer species. When they interact, they begin to build a simple biological community (that's initial, of course). The community becomes more complex as more and more species arrive.

oxygen = 21% of the atmosphere

nitrogen = 78%

carbon dioxide = 0.1%

argon =0.934%