Cupressus arizonica var. stephensoniihttp://dx.doi.org/10.2305/IUCN.UK.2013-1.RLTS.T33999A2839907.en
|Scientific Name:||Cupressus arizonica var. stephensonii|
|Species Authority:||(C.B.Wolf) Little|
Callitropsis stephensonii (C.B.Wolf) D.P.Little
Cupressus arizonica Greene subspecies stephensonii (C.B.Wolf) A.E.Murray
Cupressus stephensonii C.B.Wolf
Hesperocyparis stephensonii (Jeps.) Bartel
|Taxonomic Source(s):||Farjon, A. 2010. A Handbook of the World's Conifers. Koninklijke Brill, Leiden.|
|Taxonomic Notes:||There is a lack of agreement over the variety's taxonomic status. Some consider it to be a good species rather than a variety.|
|Red List Category & Criteria:||Critically Endangered B2ab(iii,v)c(ii,iv) ver 3.1|
|Reviewer(s):||Thomas, P. & Gardner, M.|
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, hence this results in extreme fluctuations in population size. This management is now undertaken in the USA but, as far as we know, not (yet) in Mexico. This variety meets the criteria for listing as Critically Endangered.
|Previously published Red List assessments:||
This variety is now known only 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.
Native:Mexico (Baja California); United States (California)
|Estimated area of occupancy (AOO) - km2:||4-5|
|Extreme fluctuations in area of occupancy (AOO):||Yes|
|Number of Locations:||2|
|Lower elevation limit (metres):||900|
|Upper elevation limit (metres):||1370|
|Range Map:||Click here to open the map viewer and explore range.|
Approximately 1,000 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. Around 200 mature individuals now remain in the US subpopulation.
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||
It is found 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.
|Continuing decline in area, extent and/or quality of habitat:||Yes|
|Generation Length (years):||30|
|Use and Trade:||No use or trade occurs.|
This variety was previously listed as Vulnerable, however, the last 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.
The future of this variety appears now to rest in the hands of those charged with restoring the main site in California (USA). At this time, that chiefly consists of supporting re-establishment of cypress (which has doubtless experienced such calamitous burns at intervals of a few hundred years in the past). As of April 2007, successful post-fire seedling establishment was observed in several locations within King Creek R.N.A., with dense stands of saplings up to about 0.7 m tall growing in the best sites (Earle 2010). Species management guidelines are adopted in Cleveland National Forest.
|Citation:||Farjon, A. 2013. Cupressus arizonica var. stephensonii. The IUCN Red List of Threatened Species 2013: e.T33999A2839907. http://dx.doi.org/10.2305/IUCN.UK.2013-1.RLTS.T33999A2839907.en . Downloaded on 08 October 2015.|
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