Endemic to Baja California in Mexico. The small population is vulnerable to fire and grazing
Distribution
Endemic to Mexico in Baja California Sur (Sierra de la Laguna). The population is restricted to a small area on the mountain where it does not occur in pure stands of any extent, but mixed mainly with oaks. The population size is estimated to be at least 1000 trees.
Habitat and Ecology
The Sierra de la Laguna is a batholitic uprising of granitic rock, flanked by older sedimentary rocks and rising to 2090m. Pinus cembroides subsp. lagunae occurs in the highest northern part of the range, at elevations between 1600 to 2050m. It is best developed on and around the high meadow (La Laguna) of sandy loam, but occurs also in valleys with coarse gravel or granite boulders, as well as on granitic slopes. It is commonly associated with Quercus devia, which is more abundant than Pinus in most areas. No other pines occur in Baja California Sur. On dry slopes Yucca, Calliandra and Dodonaea are found in the understorey. The climate is subtropical; annual precipitation in the area is ca. 750mm, almost all of which comes from summer rainstorms. Phenology: pollen dispersal occurs in May-June (Passini & Pinel, 1987).
Human Uses
No current uses have been recorded but the species was logged in the past.
Conservation Status
Global status
Vulnerable D2
Global rationale
The area of occupancy is calculated to be as little as 11km², based on herbarium specimens collected from 11 known localities. This may be an underestimate. These localities represent 2–3 locations with the total population size estimated to be more than 1000 trees, based on the field experience of this assessment's author. Although there is no current threat from logging or fires, this subspecies' susceptibility to stochastic events indicate an assessment of Vulnerable under the D2 criteria.
Global threats
There has been occasional but limited logging in the past. The mountain is difficult to access and there are no good roads for transport, only 4WD tracks. Grazing and fires are potential problems if they intensify or become more frequent than in the past.
Conservation Actions
The population occurs within a protected area and logging has stopped.
References and further reading
Bailey, D.K. (1983). A new allopatric segregate from a new combination in Pinus cembroides Zucc. at its southern limits. Phytologia 54(2): 89-101.
Biondi, F. &J.E. Fessenden. (1999). Radiocarbon analysis of Pinus lagunae tree rings: implications for tropical dendrochronology. Radiocarbon 41:241-249.
Farjon, A. & Styles, B. (1997). Pinus (Pinaceae). Flora Neotropica. Monograph 75. The New York Botanical Garden, New York.
Farjon, A. (2013). Pinus cembroides ssp. lagunae. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.1. <www.iucnredlist.org>. Downloaded on 13 July 2013.
Passini, M.-F. & Pinel, N (1987). Morphology and phenology of Pinus lagunae.Phytologia 63(5):331-336.
Passini, M.-F. (1987). The endemic pinyon of Lower California: Pinus lagunae M.-E Passini. Phytologia 63(5):337-338.
Perry, J.P. (1991). The Pines of Mexico and Central America. Timber Press, Portland.
Piña P., F. (1987). Pruebas de adaptación de Pinus cembroides var. lagunae. In: Passini, M. F., D.. Cibrian T. and T. Eguiluz P. (eds), II Simposio Nacional sobre Pinos Piñoneros. 299-303.
