A rainbow appears over new construction near the arm of a saguaro cactus in Tucson, Ariz., in this June 22, 2000 photo. The saguaro cactus population at least in Saguaro National Park, near Tucson is soaring. Park researchers have found a hefty increase in the number of new plants over the past decade. But they caution that that doesn't necessarily translate to similar gains all across southern Arizona. Other impacts, from invasion of exotic grasses to sprawling urbanization, have a more damaging effect. (AP Photo/Tucson Citizen, Francisco Medina)