The Vanguard: why is it here ?

[Astralia]

Thanks for your answers !

Regarding vegetation, it's because at the end living memory just seem to me like "dead electrope" having no aether left in it, so can't process lightning aether or stuff with the circuits, and when we get there, we're told it's already suffering from aether depletion, hence they're short on hands or can't be reincarnated, that's why I though with those facts, everything should die

Regarding the living memory I thought the living memory was physically connected to the other floors of the Everkeep because of that (pictures below):
https://postimg.cc/rKmY3Lmz
https://postimg.cc/gw22CJf1
they say (Alisaie): map is cut off and (Shale/Cahciua) lack of map data above 11th floor. I actually may have mistaken a thing... Could it actually be the 11th floor is inside the Everkeep, I mean inside the exterior wall, and representing the exterior with the sky (as in Heaven-on-high), and the gate to the shard is actually inside the tower ? There, the potential physical link they show us is not actually there because of their lack of map data and floating on electrope thingies as Layte_Aeon said ?
Though when we're in the living memory, looking at the bottom of it, we kinda see like a pillar with a turbine working underneath, like the pillar/physical link between LM and the underneath floors (11th, S9 and all) is actually there ?

The dome isn't especially explicitly explained, but for the purposes of this conversation, it's mainly important to remember that it's a Big Honkin' Wall Of Lightning. You can't walk through it not because it's some special dimensional barrier, but because you would die, to the lightning.

Yeah I understood that part in the end, but as Layte_Aeon said as well, the dome seem to make the zone act like in a Schrodinger's cat state, that's why I was wondering whether, besides its time-sync effect, the Vanguard also acted like a gate, but seems to be not the case !

Thanks for your answers anyway, my mind is clearer now