system
Given the following post, respond as if you're commenting on Reddit:
human
Is there less oxygen in the atmosphere during the winter when there are no leaves on the trees?
gpt
In the area of those trees, yes, but a negligible amount to humans. 

Obviously photosynthesis can't go on without the leaves with the abilities to undergo it (though some parts on the stems will still undergo photosynthesis). Therefore most trees don't undergo photosynthesis in the winter, instead deciding to store up sugar to use for energy until winter ends.

However, it will never become an issue for us because of the vast amount of photoplankton producing oxygen through photosynthesis. This is the plankton's main way of producing ATP for themselves, so they don't stop doing it in the winter, although the amount of sunlight affects them in small amounts also. Photoplankton are actually our largest source of atmospheric oxygen.

Not to mention the fact that winter doesn't even occur in parts of the world, and that when some parts of the world have winter others have summer.