Most of the refuge is covered by forests that have been altered to some extent, although the original forest mass can still be found in the remoter areas and in the river canyons. The vegetation in the lower areas, towards the south, consists of tropical dry forest. Towards the north and upper areas grows a promontane moist forest.
Wildlife is scarce in the refuge, although there are numerous birds, and some mammals.
This wilderness area has been set aside to protect the watersheds of several rivers, to preserve, and to increase wildlife.