system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: if plants need CO2 to survive, how are enclosed terrariums able to thrive?

As far my knowledge goes, is my understanding plants need CO2, aside from light and water, how come a terrarium is able to keep itself alive for years without any invention?
gpt
Because your terrarium is going to have bacteria in it, maybe even tiny bugs, or big bugs if you intentionally put them there.

But say you have a plant growing in the terrarium, in the soil there is going to be bacteria. Any organic matter in the soil can be broken down by the bacteria as food, which will then release CO2 like we do, or say even if all that matter is used up, the plant grows, uses up most the CO2, what does that mean? The plant starts to die, the leaves fall off, but wit, now those leaves start rotting and getting eaten by bacteria and the carbon in those leaves gets released as CO2 again.