Complex sentence: Nowadays the island has only two permanent human inhabitants, nature reserve keepers; in addition, agents of the State Forestry Corps from Follonica live there in alternating shifts of two weeks at a time.
Split into simpler sentences: Nowadays the island has only two permanent human inhabitants, both nature reserve keepers. In addition, agents of the State Forestry Corps from Follonica live there in alternating shifts of two weeks at a time.