Plants of the Colonet Region, Baja California, Mexico, and a Vegetation Map of Colonet Mesa

Abstract

The Colonet region is located at the southern end of the California Floristic Province, in an area known to have the highest plant diversity in Baja California. A preliminary list of vouchered specimens is developed for the area, and a vegetation map for Colonet Mesa is presented. The Colonet region has at least 435 vascular plant taxa, of which 383 are native to Baja California, and 52 are endemic or nearly endemic. This list includes five local endemic taxa known only from the Colonet region, 18 taxa on the California Native Plant Society List IB of taxa that are "rare, threatened, or endangered in California and elsewhere," and three on the Mexican NOM 059 list of protected taxa. The Mexican federal government has proposed to build a major port and a new city at Colonet. To understand the potential impact of the port on the regional biodiversity, we examine three areas ---a Footprint area which will presumably be highly affected by the port, the Mesa area which contains all the known vernal pools, and a Buffer area surrounding the other two areas. The large Buffer shows the greatest number of native and endemic taxa, followed by the Mesa. The Footprint has two species of high conservation concern that are not represented elsewhere in the study area. The vegetation map of Colonet Mesa confirms the presence of large vernal pools and shows extensive maritime chaparral, neither of which has been reported from elsewhere in northwest Baja California. This report documents the high plant biodiversity of the region and highlights the rare and unique species and vegetation types of Colonet Mesa.