Brithos isn't the wasteland that some might think it is (far from it, actually). A while back (on an old mailing list) Greg commented about the natural energies of the island not being tapped:
"You speak of Arolanit, of course, where even the air is gray from being tapped. This never happened to Brithos..."
For one reason why, the mother of the Brithini was the land goddess Britha herself:
"The Brithini were a powerful human race from before the darkness. Their Founder was named MALKION and they are sometimes called the Malkioni. Malkion had four sons and one daughter by the goddess Britha, an earth deity."
Brithini/Zzaburi exploitation of nature took a variety of forms, not just tapping; for example:
"Zzabur, the Sorcerer Supreme, who was capable of making nature work for him, such as when he made the windmills to help heat his cities. He did this by proving to his people that Malkion had created the world for them to exploit."