Cupressus arizonica var. stephensonii (C.B.Wolf) Little
Endemic to the US-Mexican border where fire is a major threat
Known from just from two localities on either side of the US-Mexican border. One consisting of a few scattered trees near the headwaters of King Creek on the southwest side of Cuyamaca Peak, San Diego County, the other 2 km NE of El Rincón in Arroyo Seco.
Approximately 1000 individuals existed in the Cuyamaca Peak subpopulation before the 2003 fires. More trees than this are likely to have existed before the Conejo fire of 1950 which already extirpated part of the population. Most of the remaining subpopulation was burnt in the October 2003 Cedar Fire, though (as expected for a fire-climax species) subsequent regeneration has been good. Fires have also occurred in the Mexican subpopulation, but to what extent these were destructive is not recorded.
Habitat and Ecology
In chaparral leading up to Pinyon-Juniper woodland and oak woodland, with Pinus coulteri, Juniperus californica, Quercus spp., Adenostoma fasciculatum, Arctostaphylos glandulosa, Ceanotus spp., Cercocarpus spp., Rhamnus spp., on dry slopes and ridges above creek beds. It is the only California Cypress to release pollen in the summertime.
Critically Endangered B2ab(iii)c(ii,iv); C2b
There are two subpopulations, one in Alta California (USA) and one in Baja California (Mexico). The one in the USA has experienced two devastating fires since 1950, reducing the number of mature trees by 90% or more. The other subpopulation in Mexico has also been subject to fires, but no population numbers are known. Regeneration is occurring after fire, but it is slow and when fires become more frequent, may not be successful without careful management. This management is now undertaken in the USA but, as far as we know, not (yet) in Mexico. This variety meets two criteria for Critically Endangered.
The previous IUCN Red List assessment occurred in 1998, before the USA subpopulation of this taxon was reduced to thirty or forty individual trees by the 2003 Cedar Fire. This remnant subpopulation is now under active management but numbers are so low that the population could be wiped out very easily by fires, invasive pests or fungus attack. Because the surrounding forests are managed the species may also be threatened by fire suppression which could lead to a lack of reproduction and a build up of resin which will cause very hot fires, if started, which the species will not be able to cope with. The situation with the other subpopulation in Mexico is less well known but there is unlikely to be active management at present.
Species management guidelines are adopted in Cleveland National Forest.