In general, leafy deciduous
trees that are not resinous (of which black locust is one such) are not nearly as flammable as others....for instance conifers and eucalypts, as you mention. So planting them around, or replacing flammable species with them,
should help with fire danger. That said, anything will burn if the heat is intense
enough, and it is always important to maintain clear space on the ground and between trees; especially near buildings.