Gotta get mechanical. A disk does three things: disturbs the soil, with enough passes it will kill and bury broomstraw/sage, and brings dormant seed up from below for it to sprout. Fire is great for large scale and cost efficiency, but the most bang for the buck is going to come from a big tractor and heavy ass disk.

I was thinking about the best way to describe what "early successional" habitat is to people the other day, and it occurred to me just to tell people to imagine their garden if they disked it up real nice and didn't plant anything. A years growth of weeds is early successional habitat.