Picea engelmannii ssp. mexicana
|Scientific Name:||Picea engelmannii Parry ex Engelm. ssp. mexicana (Martínez) P. Schmidt|
Picea mexicana Martínez
|Taxonomic Source(s):||Farjon, A. 2010. A Handbook of the World's Conifers. Koninklijke Brill, Leiden.|
|Taxonomic Notes:||This subspecies is sometimes treated as a distinct species that is endemic to Mexico. The IUCN Red List follows the taxonomy of the Conifer Database in Species 2000 & ITIS Catalogue of Life (Farjon 2010). Here, it is treated as a subspecies of Picea engelmannii. Although the subpopulation in the Chiracahua Mts in Arizona appears to be genetically more closely related to the typical subspecies (Ledig 2004), for the purposes of this assessment it is included within subsp. mexicana.|
|Red List Category & Criteria:||Endangered A4acd; B2ab(ii,iii,v) ver 3.1|
|Assessor(s):||Thomas, P. & Farjon, A.|
|Reviewer(s):||Perez de la Rosa, J. & Stritch, L.|
This subspecies has undergone an estimated recent decline (post 1950) of up to 50%. A further decline is likely so that the overall decline is estimated to be greater than 50% by 2025. This time period is within the three generation period required by the IUCN to qualify for Endangered under the A4 criteria. In addition, the area of occupancy is much less than 100 km2, there are only three known locations, subpopulations are severely fragmented and there is a continuing decline due to grazing, fire and logging.
|Previously published Red List assessments:|
|Range Description:||Mexico: southern Chihuahua, Nuevo León; USA: Arizona, Chiricahua Mts. |
In Mexico, this spruce is found only on the two tallest peaks of the Sierra Madre Oriental in the states of Coahuila and Nuevo León and on the tallest peak of the Sierra Madre Occidental in the state of Chihuahua, 676 km distant (Ledig 2010).
Native:Mexico (Chihuahua, Nuevo León); United States (Arizona)
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||The subpopulations are small. The largest one, from La Carmen in the Sierra de la Marta, was virtually destroyed in a fire in 1975 (“reduced to a population of a mere 6 mature trees”, Rushforth, 1986) although later surveys revealed that an estimated 1000-2000 trees remained on the upper slopes (Ledig et al. 2002). Regeneration is hampered by grazing.|
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||This subspecies is restricted to high altitude, N-facing slopes and ravines on limestone mountains.|
|Continuing decline in area, extent and/or quality of habitat:||Yes|
|Generation Length (years):||40|
|Use and Trade:||There is no trade, but locally some trees may have been felled and used for timber.|
|Major Threat(s):||The main population in the Sierra de la Marta (the type locality) was nearly exterminated in a forest fire in 1975. Other populations, e.g. on Cerro Mohinora in Chihuahua, are much smaller and declining, and even more susceptible to destructive fires. In addition, trees have been felled while regeneration is poor and slow due to grazing, especially on Cerro del Mohinora. Global warming presents a further threat as each subpopulation is growing close or on the summit of their respective mountains and there is little scope for further migration.|
This subspecies is present in one protected area (Chiricahua Mts., Arizona). Despite this that subpopulation is vulnerable to human set fires that are likely associated with illegal immigration and drug trafficing into the USA from adjoining areas of Mexico are increasingly common. The most recent fire (Horshoe 2) burnt over 200,000 ha of pine-oak and mixed conifer woodland in 2011 (US Forest Service 2011).
The Mexican subpopulations are outside formal reserves. The remaining stands of this subspecies should come under such protection, where logging, grazing and burning can be policed and controlled. Ex-situ conservation involving the collection of seed from all stands and the establishment of breeding populations in suitable areas should be a priority.
According to the Secretaría de Medio Ambiente y Recursos Naturales (Mexico) (2010) this species is in danger of extinction.
|Citation:||Thomas, P. & Farjon, A. 2013. Picea engelmannii ssp. mexicana. The IUCN Red List of Threatened Species 2013: e.T33922A2839137.Downloaded on 18 October 2017.|
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