A better analogy would be anything that can be expressed in volumes. For this reason, "4 football stadiums" and "2 school buses" would actually be pretty good.
Anyway, most trees can't.
...it's a rate, it would be bananas/hr.
I ran the calculations, 6 grams an hour seems to be about 15% of a single astronaut's oxygen consumption.
The planned larger machine they talk about, about the size of a chest freezer producing 3 kilograms of oxygen an hour, should be enough for ~85 astronauts. Though I assume that's also needing to produce rocket oxidiser for the return trip.
There will most likely be insects, bacteria, fungi; All which also consume oxygen.
On top of organic things, the Earth2 experiment famously ran into a problem where the concrete they used to build the biosphere kept curing long after construction finished, and kept sucking oxygen out of the atmosphere.
And don't forget to take into account that NASA's machine can produce oxygen all day, everyday, where trees stop producing oxygen at night, and over winter (and actually start consuming oxygen)
> Managing CO2 levels was a particular challenge, and a source of controversy regarding the Biosphere 2 project's alleged misrepresentation to the public. [...] The crew worked to manage the CO2 by occasionally turning on a CO2 scrubber [...] In November 1991, investigative reporting in The Village Voice alleged that the crew had secretly installed the CO2 scrubber device, and claimed that this violated Biosphere 2's advertised goal of recycling all materials naturally.
> A mystery accompanied the oxygen decline: the corresponding increase in carbon dioxide did not appear. This concealed the underlying process until an investigation by Jeff Severinghaus and Wallace Broecker of Columbia University's Lamont Doherty Earth Observatory using isotopic analysis showed that carbon dioxide was reacting with exposed concrete inside Biosphere 2 to form calcium carbonate in a process called carbonatation, thereby sequestering both carbon and oxygen.
It's like someone saying, "hey I knew your cousin Dan". Nice, I have no idea of their relationship but they're trying to "break the ice" so to speak with an irrelevant tidbit.
In there any species of tree that would be intimately known to a global anglophone audience?
It's not a very good comparison to communicate to a lay audience. A far, far better one would be in terms of "resting oxygen requirement of an average human."
Like maybe they aren't seriously insisting they can believe that "small" tree does refer to a 40+ft tree.