Northern Mexico / SW USA

The Mexican and southwest USA Threatened Conifer Region stretches from central southern California south to the Guatemalan border. In the north a broadly Mediterranean climate prevails with summer droughts a major limiting factor. In Mexico, conifers occur in a range of climates that include cold subalpine areas of the highest volcanoes and the lush, lowland tropical forests. Most species are found in the pine-oak woodlands that once covered extensive areas of the many mountain ranges in Mexico.  This region is important for conifer diversity and is the main centre for the genus Pinus with over 50 species which represents 50% of all known species. Unfortunately this region has the highest number of threatened taxa with more than 60  mostly being threatened mainly by widespread over-exploitation, fire and the conversion of forests for agriculture. Many species are narrow endemics of relictual origin with small populations close to the tops of mountains. These taxa are particularly vulnerable to the impacts of changes to precipitation associated with climate change. 

Taxa in the category - Northern Mexico / SW USA :

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Pinus nelsonii Shaw

Occurs in the southern part of the Sierra Madre Oriental of Mexico, its main threats are cattle grazing and fire Read full species entry >

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Pinus radiata D.Don

Distributed on the Pacific coast of California and on two islands off the coast of Mexico, it is threatened by feral goats on the islands and by an introduced pathogen, and competition from other trees in the absence of periodic fires on the mainland Read full species entry >

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Pinus radiata var. binata (Engelm.) Lemmon

Endemic to two small islands off the coast of Baja California, Mexico: the main threats are pitch canker, impacts of possibly frequent fires, climate change, and introduced species Read full species entry >

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Pinus radiata var. radiata

Endemic to central-coastal California, USA where the three remaining stands are mainly threatened by fire, pitch canker and urbanisation. Read full species entry >

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Pinus rzedowskii Madrigal & Caball. Del.

Endemic to western Michoacan, Mexico where it is threatened by fire Read full species entry >

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Pinus torreyana Parry ex Carrière

Distributed in California, USA with two subspecies, one on the mainland and one on Santa Rosa Island. Both have very restricted distributions and small population sizes. On the mainland, outside of the main protected area of Torrey Pines State Park it is threatened by urbanisation. Read full species entry >

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Pinus torreyana subsp. insularis J.R.Haller

A very small population found on Santa Rosa Island in California, USA where potential threats include pests and diseases and fire. Read full species entry >

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Pinus torreyana subsp. torreyana

Although afforded some protection within the Torrey State Reserve in California, USA, unprotected trees are threatened by urbanisation Read full species entry >

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