After further review of this area, these are unnamed "closed areas".  That's what is on the maps from https://www.openspace.org/.  They're not a part of an existing named preserve. It's just "Closed Area". They're managed by the Midpeninsula Regional Open Space District, which is managed by publicly elected officials, or perhaps the Peninsula Open Space Trust, which is a non-profit land trust that collaborates with Midpeninsula Regional Open Space. They're 2 sides of the same coin. Entering a closed area is punishable as an infraction or a misdemeanor according to https://www.openspace.org/trail-use-regulations. They're being preserved in their natural state.

The roads and areas have been marked as access=no or access=private as appropriate. The names have been updated to note ownership, but also leave "closed area" in the name to reflect the maps from the open space organizations.