Why did the mane six have to give them up? (Spoilers for Season 4)

[Hailcanuseacomputer 19]

We know the mane six gave up the elements to save the tree of harmony, but they said "Even without the elements the tree with posses a powerful magic." So couldn't they put them in then a 2-5 episodes later take the elements out? I just don't get it.

[Banul 3,831]

I assume that, if they were to take the elements out of the tree, Everfree Forest would start growing out of control again. We don't know how long it would take for the forest to start acting up after the elements are gone. They probably didn't want to risk it.

[Castle Bleck 19,446]

We don't know how long it would take for the forest to start acting up after the elements are gone.

 

The first time took 1,000+ years. Surely they could've spared, say, 10 minutes.

Edited August 14, 2014 by A.V.

[Banul 3,831]

The first time took 1,000 years. Surely they could've spared, say, 10 minutes.

That's how long it took initially. I always though that the tree of harmony is just keeping the plunder seeds at bay now, and that if the elements are removed the forest would start acting up immediately. I suppose that's more of a head canon, but we don't really know for sure what would happen if the mane 6 took the elements back. I guess I assume that if the ponies could have used the elements again, they would have.

[Pastel 7,630]

I guess if they took the elements back, the vines would have reappeared.

 

[Rainboom Dash 1,056]

They had to keep them there, to control the forest.

 

Besides, they have their powers back in the form of Rainbow Power.

[Old Fluttershy 349]

Have they really needed the elements since they gave them back to the tree?

The only real incident was Tirek but

1. they all believed Discord was taking care of it

2. by the time they found out, Tirek had captured Twilight's friends and they got the final key anyway

[Moved to Elsewhere 11,331]

I'm pretty sure not having the elements there would keep the tree from attacking.