Other true grasses do exist out there, but much of this is a sedge species. Likely, more frequent fire, or differing timings would shift species composition towards true grasses. In general, hotter growing season fire favors herbaceous plants, cool dormant season favors woody plants like scrub oak. Early growing season favors grasses, later growing season favors forbs and flowers. I don't know about sedges, but I think the Mullica fires were later in the summer.