Transboundary Madrean Watersheds Final 12_2015

The Transboundary Madrean Watersheds proposed pilot area covers approximately 18 million hectares of four states in two countries: Arizona and New Mexico in the U.S., and Sonora and Chihuahua in Mexico. Boundaries were determined by hydrographic basins to ensure continuity among freshwater and terrestrial communities and are as follows: to the north the Gila River watershed; to the west the Santa Cruz River watershed into Mexico, the arroyo Cocóspera watershed, the Upper Río Sonora and the limits of the DLCC Geography; to the south: the Tutuaca Natural Protected Area, and the CEC’s priority grasslands area of Valles Centrales; and to the northeast the closed basins of Casas Grandes. The Area, includes the Madrean Archipelago (MA), characterized by isolated forested mountain ranges surrounded by a “sea” of intervening flatlands, and expands east to include adjacent grasslands. The MA is a unique mid-latitude sky island complex where temperate and subtropical climatic regions interrelate with tropical climates, it forms a corridor between two important mountain ranges in North America: the Rocky Mountains and the Sierra Madre Occidental. Notable resources of management concern within the Area include water and riparian ecosystems, as it encompasses the headwaters of two major economically significant basins: the Colorado and the Yaqui. It also includes the largest grasslands in the DLCC geography as well as significant portions of thornscrub ecosystems, some of the most endangered and unknown in the Sierra Madre Occidental, and forests under varying management regimes, all of them important as carbon sinks and erosion buffers, as well as relevant for their complex hydrology.

Ecological integrity in the Area is as diverse as its other features. While the Area encompasses urban, mining and agricultural areas that are heavily degraded, it also holds some of Mexico’s last standing remnants of temperate old growth forests, the best-preserved cienegas in any North American grassland, one of the largest black tail prairie dog colony complexes anywhere, the few remaining herds of Mexican pronghorn, and reintroduced Mexican wolves on both sides of the border, all in need of increased protection. It also encompasses ecosystems needing or undergoing active restoration and rehabilitation through better water, soil, ecosystem, and fire management.