Southwestern Flora
New Mexico
New Mexico supports remarkable plant diversity parallel to diverse landscapes that range from the striking white sand dunes of the northern Chihuahuan Desert to the barren alpine tundra of Wheeler Peak. The landscape is defined by intense temperature, precipitation, and elevation gradients that give rise to eight distinct Omernik Level III Ecoregions and the fourth highest floristic diversity in the country, comprised of 3,305 vascular plants, 90 of which grow nowhere else in the world but New Mexico (Stein, 2002). New Mexico’s major vegetation types include grasslands, pinyon-juniper woodlands, forests, shrublands, riparian/ wetlands, alpine tundras, as well as the important ecotones, or transition regions, where these vegetation types connect (Allred & Dewitt Ivey, 2012). Examples of plant communities include the southernmost sagebrush communities of the United States, creosote and mesquite shrublands, eastern grasslands, pinyon-juniper woodlands and savannas, and ponderosa forests.
arizona
Ranked as the third highest floristic diversity in the country, Arizona is home to over 3,500 vascular plants (Stein, 2002). Arizona's biodiversity reflects the intricate interplay of climate, topography, geology, and its biogeographic position at the meeting place of three major deserts (the Mojave, Sonoran, and Chihuahuan), canyon-carved plateaus, and mountain-cradled basins bisected by desert river systems. Major vegetation types included desert scrub, Saguaro cactus forests, pinyon-juniper woodlands, semi-desert grasslands, ponderosa pine and coniferous forests, Madrean evergreen woodlands, and riparian zones with cottonwood gallery forests.
At Risk Flora and Conservation Needs
Unfortunately, over 12% of vascular plants in New Mexico and 15% in Arizona are considered at risk (Stein & Gravuer, 2008, NatureServe 2002). These species face additional challenges caused by climate change and expected associated ecological changes, which are especially significant for small populations with restricted ranges, including many of the species endemic to New Mexico. A report in the western U.S., exploring vulnerability trends in response to climate change relating to geography, conservation status, and taxonomic affiliation, revealed that the greatest concentrations of taxa vulnerable to climate change are found in arid to semi‐arid regions of the southwestern states (Treher et al., 2012). The New Mexico Endangered Plant Program lists 235 plant species as rare and imperiled, with 103 species that are considered globally imperiled, and 109 species that occur only in New Mexico (EMNRD – Forestry Division, 2017).
These statistics are enough to light a fire under botanists and restoration ecologists here in the Southwest. We are working to preserve Southwest biodiversity by collecting seeds and, through restoration efforts, putting ecologically appropriate plant species out onto the landscape following wildfires or anthropogenic disturbances such as recreation or oil and gas development.
To learn more about Arizona and New Mexico's rare and endangered plants visit the Arizona Native Plant Society Website, New Mexico Rare Plant Website, and the New Mexico Endangered Plant Program Website.
Citations:
Allred, K. & Dewitt Ivey, R. 2012. Flora Neomexicana III: An Illustrated Identification Manual. Las Cruces, NM: Kelly W. Allred (privately published).
EMNRD – Forestry Division. 2017. New Mexico Rare Plant Conservation Strategy. Prepared by D. Roth and developed by the NM Rare Plant Conservation Strategy Partnership. Santa Fe, NM.
Stein, B.A. and Gravuer K. 2008. Hidden in Plain Sight: The Role of Plants in State Wildlife Action Plans. Arlington, Virginia: NatureServe.
Stein, B. A. 2002. States of the Union: Ranking America’s Biodiversity. Arlington, Virginia: NatureServe.
Treher A., A. Frances, L. Oliver, and B.E. Young. 2012. An analysis of the vulnerability of plants on BLM lands to climate change. BLM Purchase Request No. 0020002338, Agreement # L07AC14909. Arlington, Virginia: NatureServe