"Fecund" means productive, whether physically or intellectually. Rabbits are fecund. Agricultural land can be fecund. Beehoven was a fecund composer.

He has a fecund imagination

The fecund years of the Italian renaissance contributed greatly to modern art. (idk if that's true but fecund is used correctly)

No. Second means next after first, while fecund means fertile.

The writer may be referring to the theory that black holes could spawn new universes (Smolin's Fecund universe). This is highly theoretical is a along way from being proven.