Aerial Information Systems (AIS) was contracted by the Midpeninsula Regional Open Space District (MROSD) and the Peninsula Open Space Trust (POST) to create a vegetation inventory of their properties and surrounding areas. Several mapping efforts were completed between 2000 and 2007: Sierra Azul and environs, 2000; Las Pulgas Preserve, 2003; Purisima Creek and environs 2005; Teague Hill and Thornewood preserves, 2006; POST's S. San Mateo map, 2007; La Honda Creek and environs, 2001; and an area that encompasses a number of preserves near Skyline Rd., 2003. The maps were seamed together and dissolved on the veg. type by the MROSD. Some of the individual maps were also sent to CDFW--but at least one of these (La Honda) looks like an older version of the map used in the seamed version. For this reason, the density (cover class) attribute was added to the seamed version by using spatial joins to the individual maps. This means that the polgyons that were split on density, not veg type do not have a density value,