The words for forest and jungle in french are "foret" (or bois) and "jungle" Unless Brieuse is derived from an Old French word, (which is very possible), it doesn't mean forest.
According to BtN, it orginated as a surname, which itself began as a place name:
BRUCE Gender: Masculine Usage: Scottish, English Pronounced: BROOS [key] From a Norman surname meaning "of Brieuse" in French. Brieuse was a place in France. The name was borne by Robert the Bruce, a Scottish hero of the 14th century who achieved independence from England and became the king of Scotland.
"Les yeux sont aveugles. Il faut chercher avec le coeur." -- Le Petit Prince, Antoine de Saint-Exupery