: As old leaves die and fall, microorganisms in the soil decompose them, returning vital nutrients to the earth to feed new growth.
: Sunlight warms the air inside, causing moisture to evaporate from the soil and leaves (transpiration). This water condenses on the glass and "rains" back down into the soil. Bottle Biosphere Guide
A successful bottle biosphere relies on three primary cycles to stay alive: : As old leaves die and fall, microorganisms