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Setting Priorities

Sonoran Desert Ecoregional Plan: Overview

The Nature Conservancy defines its conservation priorities through the process of ecoregional planning. One example of where the Conservancy conducted this work is in the Sonoran Desert Ecoregion in the southwest U.S. and northwest Mexico—a land of stunning biological diversity including ancient lava flows, shifting sand dunes, strange cacti, ephemeral waterways, unique native fish and frog populations, and a host of plant and animal life adapted to the extreme conditions of the desert.

The Sonoran Desert is also a fragile landscape and its biodiversity is under siege. In 1990 the region contained 6.9 million residents, nearly double the population size in 1970. By 2020 the population is expected to reach 12 million! As human population grows, native habitat is converted, scarce water resources are increasingly apportioned to human uses, and other growth-related impacts strain the viability of the region’s biodiversity.

In the late 1990s The Nature Conservancy facilitated a binational, public-private collaboration to put together a blueprint for conservation action within the ecoregion. This was completed in April 2000.

Sonoran Desert Ecoregion Facts

• Ecological Significance: This ecoregion has more than 200 imperiled species and numerous plants, reptiles, and fish rarely found elsewhere. It is the most tropical of the three North American warm deserts (Chihuahuan, Mohave, and Sonoran).
• Size: 55 million acres
• Location: Parts of California, Arizona and the Mexican states of Sonora and Baja California
• Animal Species: In the desert's lower elevations, roadrunners and fringe-toed lizards sprint across sizzling sands and the endangered nomadic Sonoran pronghorn roam. The mountains are home to majestic desert bighorn sheep.
• Plant Species: Creosotebush and bursage shrubs dot the low desert. In the bajadas that slope down from the mountains, forests of saguaro cacti, paloverde, and ironwood team with life. Higher up, plant species dating back from the Ice Age can still be found.
• Conservation Concerns: In Mexico most Sonoran Desert land is privately or communally held and only a small percentage has official protection or conservation status. In the United States the majority of the Sonoran Desert Ecoregion is in public ownership, but only 25 percent of these public lands are adequately protected, and there is increasing pressure to use publicly owned lands for purposes not compatible with biodiversity preservation.

Learn more about how The Nature Conservancy set conservation priorities in the Sonoran Desert ecoregion by:

• Identifying Conservation Targets
  Ecoregional planning teams made up of Conservancy staff and partners identify the species, natural communities and ecosystems in a given ecoregion.
• Gathering Information
  The teams gather data about the conservation targets, such as location and health, from a variety of sources including the Natural Heritage programs, satellite images and rapid ecological assessments.
• Setting Goals
  Ecoregional planning teams set goals for each of the conservation targets. Setting conservation goals involves determining how much of a particular target— a population or ecosystem, for instance—is needed to ensure its long-term survival. A conservation goal also includes how the target needs to be distributed across the landscape.
• Assessing Viability
  The team also assesses the health of each occurrence of each conservation target to ensure survival over the long term by choosing the best and most healthy examples of each target.
• Assembling Portfolios
  All this information is analyzed by the teams and expert partners and often through computer modeling to design an efficient network of conservation areas (or portfolio) that if protected in its entirety will ensure the preservation of biodiversity within the ecoregion.