How does spell casting work with regards to concentration and multiple spells?
The other players in my group are arguing that duration-based spells require concentration and the casting of any other duration-based spell would cause the first to disappear.
For example, they say that if I cast Produce Flame, that is the only spell I can cast until I have used the spell entirely, or if I choose to cast another spell such as Flaming Sphere then Produce Flame's effects end as I'm no longer concentrating on it, even though the duration specified has not ended.
I find this interpretation extremely limiting on spellcasting, especially as a druid, as it means I can't ever use multiple spells that have durations of more than one turn, like Summon Nature's Ally, Entangle, Flaming Sphere and others.
The way I understand it is that only spells specifying concentration in its use, such as Summon Swarm, require the user to actively concentrate on the spell, and that only another of these concentration-based spells would cause the first to cease and that the casting and use of multiple non-concentration spells was fine.