Turles brings a seed to Earth that can drain the planet's life into a vast tree. Goku and his allies must confront the invader before that growth leaves nothing else able to survive. Turles' resemblance to Goku makes the threat especially unsettling: a familiar face accompanies a purpose aimed at consuming the world.
The opening ties the conflict to a forest and its animals before the tree threatens life on a planetary scale. Gohan's concern for the creatures around him gives that danger a smaller, concrete point of contact. This profile counts the original theatrical feature once, with dubbed and repackaged editions kept within that same identity.
Gohan is surrounded by members of his family and their friends around a picnic meal. The ordinary gathering gives the threatened environment a use beyond providing space for a fight: it is somewhere they can spend time together. The attack intrudes on that shared setting before its consequences extend far beyond the group.