I received an answer that the clearing was, as I suspected, part of the management plan and not something else.
I was told it is a prelude to a future prescribed fire.
The site has never been burned in modern times and has fewer open areas than the north tract.
It has different vegetation, too.
The only good patch of Rosemary, which will regenerate after the fire, is in the south tract. So is most of the Polygonella basiramia, though most of it's in the north fire lane next to Stewart Auto Repair.
According to some FNAI data I received when I first started volunteering, there's an old (1950s) record for Carter's Warea on this section. Perhaps the fire will bring it out if the seed bank is still here.
On the other hand, there is no Bonamia grandiflora and very little Nolina brittonia in this section, at least in its unburned state.
This site appears to have a much larger population of Polyphylla starkae than the north tract, but that impression is based solely on one year's incidental observation.