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Abstract
The Sierra Madre Occidental (SMO) is the largest continuous ignimbrite plate on Earth. Despite its high biological and cultural diversity and enormous environmental and economical importance, it is yet not well known. We describe the vegetation and present a preliminary regionalization based on physiographic, climatic, and floristic criteria. A confluence of three main ecoregions in the area corresponds with three ecosystems: Temperate Sierras (Madrean), Semi-Arid Highlands (Madrean Xerophylous) and Tropical Dry Forests (Tropical). The Madrean region harbors five major vegetation types: pine forests, mixed conifer forests, pine-oak forests, oak forests and temperate mesophytic forests. The Madrean Xerophylous region has oak or pine-oak woodlands and evergreen juniper scrub with transitions toward the grassland and xerophylous scrub areas of the Mexican high plateau. The Tropical ecosystem, not discussed here, includes tropical deciduous forests and subtropical scrub. Besides fragmentation and deforestation resulting from anthropogenic activities, other dramatic changes are occurring in the SMO, including damage caused by bark beetles (Dendroctonus) in extensive areas, particularly in drought-stressed forests, as well as the expansion of chaparral and Dodoneaea scrub at the expense of temperate forest and woodlands. Comments on how these effects are being addressed are made.
Parent Publication
Keywords
Madrean Archipelago,
Sky Islands,
southwestern United States,
northern Mexico,
natural environment,
fauna,
flora,
research,
management,
biodiversity,
climate change
Citation
Gonzalez-Elizondo, M. S.; Gonzalez-Elizondo, M.; Gonzalez, L. Ruacho; Enriquez, I. L. Lopez; Renteria, F. I . Retana; Flores, J. A. Tena. 2013. Ecosystems and diversity of the Sierra Madre Occidental. In: Gottfried, Gerald J.; Ffolliott, Peter F.; Gebow, Brooke S.; Eskew, Lane G.; Collins, Loa C. Merging science and management in a rapidly changing world: Biodiversity and management of the Madrean Archipelago III and 7th Conference on Research and Resource Management in the Southwestern Deserts; 2012 May 1-5; Tucson, AZ. Proceedings. RMRS-P-67. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. p. 204-211.
