Locality: (32.041700, -112.875400)
Abstract: The contiguous Organ Pipe Cactus National Monument, Cabeza Prieta National Wildlife Refuge, and the Tinajas Altas region within the Sonoran Desert in southwestern Arizona have a vascular plant flora of 736 taxa (species, subspecies, varieties, and hybrids) in 420 genera and 94 families. Elevation and ecological diversity decrease from east (Organ Pipe) to west (Tinajas Altas) while aridity increases from east to west, all correlating with decreasing botanical diversity. Organ Pipe Cactus National Monument, which includes an ecologically isolated Sky Island of dwarfed woodland rising above actual desert, has a flora of 657 taxa in 395 genera and 93 families, of which 11 percent (72 species) are not native. Cabeza Prieta National Wildlife Refuge has a documented flora of 426 taxa in 266 genera and 63 families, of which 8.8 percent (37 species) are not native. The Tinajas Altas region has a flora of 227 taxa in 164 genera and 47 families, of which 5.3 pecent (12 species) are not native. Non-native species make up 10.7 percent (78 species) of the total flora of the three areas, but among these only 7 percent (52 species) are established in the flora area as reproducing populations. Six non-natives have become invasive species that pose serious threats to the native ecosystems: Sahara Mustard (Brassica tournefortii), Red Brome (Bromus madritensis subsp. rubens), Buffelgrass (Cenchrus ciliaris), Arabian and Mediterranean Grass (Schismus arabicus and S. barbatus), and Tamarisk (Tamarix chinensis).
Notes: 330,689 Acres
