Each July, when the monsoon season rolls across the desert, the silky yellow flowers of the Pima pineapple cactus burst into bloom. Sweet, green, succulent fruit soon follows, providing essential food and water to a number of desert animals. But w ith most of the plant’s range in Pima County -- home to sprawling Tucson -- development and illegal collecting mean fewer of these cacti bloom each year.
From a distance, the Pima pineapple cactus resembles a small barrel cactus. But on closer inspection, it is easy to see that this species is different because of the numerous spine clusters with one straw-colored, hooked central spine surrounded by several smaller, straight spines. The cactus grows in semi-desert grassland and in Sonoran desert scrub between an elevation of 2,300 and 5,000 feet. Its range extends just 45 miles east to west and 50 miles north to south, in southeast Arizona and north-central Sonora. Within this range , it averages less than one plant per four acres.
The Smithsonian Institution recommended in its 1975 report on 1,726 imperiled plants that the Pima pineapple cactus be listed as threatened. However, like many other plants in that petition, the cactus languished unprotected for years as populations declined further. Finally, it was listed as an endangered species in September 1993. Today, only about 1,500 individual cacti remain in the United States.
...in a shrinking desert
Habitat loss is a major threat to this species from urban development, off-road vehicle use, road construction, livestock grazing, agriculture and mining. Nonnative grasses prevent new plants from taking root. Finally, illegal collecting threatens the Pima pineapple cactus, despite protection under the Arizona Native Plant Law. But the primary threat has been sprawling development in several urban areas within the cactus’s small range; it is estimated that up to 75 percent of its current range could be lost to urban development around Tucson in the next few years.
Efforts have been made within Pima County to control threats to the cactus: a 590-acre mitigation bank, a fenced population at the county’s Motorsports Park, a Buenos Aires National Wildlife Refuge fire crew that burns donut-shaped rings around individual cacti to protect them from prescribed burns through the grassland. But such conservation efforts are piecemeal, and mitigation that allows original habitat to be destroyed is rarely if ever adequate. In Pima County, 23 plants and animals are threatened or endangered, most because their habitat has been destroyed or damaged. To save remaining desert, the Pima County Board of Supervisors unanimously adopted the Sonoran Desert Protection Plan in May 1998.
When bigger is better
Drafted by the Center on behalf of a coalition of 31 environmental groups, the Sonoran Desert Protection Plan establishes a process that should conserve large swaths of desert without allowing endangered species and their habitats to be destroyed. A habitat conservation plan for 5.9 million acres, it proposes to manage human development and open space in southern Arizona to protect habitat for the Pima pineapple cactus and other endangered species.
With a growth rate of 25 percent every ten years, the increasing population of Pima County continues to encroach on more habitat. Without such a plan, conservation efforts will likely continue to be piecemeal at best, and cactus populations will very probably decline as more desert habitat is lost to uncontrolled development. The proposed Sonoran Desert Conservation Plan offers hope for the Pima pineapple cactus as well as the desert as a whole.