Distribution

Endemic to north eastern Mexico in the States of Coahuila and Nuevo León where the population has undergone a recent decline due to fires.

Habitat and Ecology

The altitudinal range of P. culminicola is 3000–3700 metres above sea-level, which includes the highest ridges of these mountains. Its habit is very similar to other mountain 'dwarf pines', e.g. P. mugo in Europe and P. pumila in NE Asia. Adaptation to blasting, ice- or sand-laden winds and a short growing season is responsible for this habit. Soils are mostly rocky and calcareous. Climatic conditions are not well known due to a lack of weather stations at these summits, but precipitation, some of it as snow, is probably abundant. On Cerro Potosí, the species forms extensive monocultures of close-packed individuals. It occurs there with scattered, stunted P. hartwegii, which indicates that the climatic tree line is not reached there at around 3700m. Somewhat lower, on the Sierra La Marta, Coahuila, P. culminicola has been found in a scrub-community with Quercus spp., Arctostaphylos, Ceanothus, Agave and grasses; on the Cerro La Viega and the Sierra de Arteaga, Coahuila, a similar vegetation, but also with Abies and Pseudotsuga, are reported growing scattered with P. culminicula. Pollen dispersal has been reported on Cerro Potosí to occur in late July, at 3690m, which indicates a late fertilization and short growing season.

Conservation Status

Global status

Endangered B1ab(ii,iii,iv,v)+2ab(ii,iii,iv,v)

Global rationale

Pinus culminicola is only known from a few mountain tops. The largest and best known subpopulation on Cerro Potosí covered several km² but they have been substantially reduced by fires in recent years. Most other subpopulations (9-10) are much smaller in extent. The area of occupancy, derived from mapping herbarium specimens, is between 10 and 20km². The actual area of occupancy is much less. The population is severely fragmented as it is restricted to mountain summits and does not occur in the intervening valleys. There has been a recent decline due to fire and a decline is predicted to continue in future unless adequate counter measures are taken. Consequently, this species is assessed as Endangered under criterion B.

Global threats

This species is vulnerable to fire during long dry periods (Perry, 1991). In recent years, devastating fires have destroyed large parts of the population on Cerro Potosí and regeneration is very slow. Grazing and trampling also inhibit regeneration (Jimenez 2005). Fires may increase in other localities when they become more frequently visited by campers etc., being in the vicinity of two major population centres. As this species has a very narrow ecological niche within the summit area it may be vulnerable to the potential effects of climate change.

Conservation Actions

Protection against man-made fires and the management of grazing is essential especially within protected areas such as on Cerro Potosí, a national park. Tourism and outdoor camping, picnicking etc. need to carefully managed. Restoration programmes at the Cerro Potosi site have been initiated (Jimenez, 2005). On a recent visit to the summit of Cerro El Potosi (April 2012), a slow recovery of populations devastated by fires was apparent (J. Perez de la Rossa unpubl. data).