More on Saguaro

Silence. Extraordinary silence. Then for a fleeting moment, the silence is punctuated by the call of a cactus wren. Yet in the midst of this hot, arid, and seemingly inhospitable landscape, life fills every conceivable void. Dramatic variations in both temperature and moisture encourage unique evolutionary adaptations, sharply defining life in the Sonoran Desert. Here perhaps as nowhere else, even a novice can "discover" the laws of nature firsthand, so little is there to cloud the view. Saguaro cactus, the stately "forest tree" of the desert, takes on a wide variety of all-too-human shapes, appearing to preside over its ground-hugging cousins, and the fauna this vegetative community supports. Life seems to explode here after the rains of early spring, in one instant elegantly renewing nature’s cycle of death and rebirth. My Experience of Saguaro Forthcoming from DeeAnn Pederson The Nature of Saguaro By Bradford Glass Where the earth’s crust was stretched like an accordion, large "pleats" mark the lands of the Sonoran Desert. The ridges of the pleats form a series of north-south running mountain ranges, so clearly visible from above -- the Sky Islands, for they form higher-altitude pockets of unique biodiversity set against an otherwise bleak landscape. The troughs of the pleats once formed valleys, as deep as the mountains were high. The millions of years that have followed this crustal upheaval have been more than enough to allow the meager amount of rainfall to erode the mountains to a shadow of their former presence. In so doing, the valleys have become filled with sediment. The city of Tucson sits atop 9000 feet of eroded sediment. Such is the land we now know as the desert southwest. With less than ten inches of rain a year, and a daily temperature range that would mean death for unprotected humans, life here is an "in your face" lesson on nature’s rules, and on the dynamics of evolutionary adaptation. Two characteristics of the desert starkly define its life forms: temperature and moisture. Four different desert regions make up the southwest United States: Sonoran, Coloradan, Chihuahuan, and Mojave. Differentiated by temperature, moisture and landform, each has unique features, observable to even the novice naturalist. Saguaro National Monument preserves true Sonoran desert environment, including a huge "forest" of Saguaro cactus, countless relatives, and the fauna supported by this seemingly hostile environment.

A New Day Old Man of the Desert

Sounds paradoxical, but anywhere nature’s resources are stressed offers a perfect place to learn. Nature has three choices for dealing with lack of water and wide ranges of temperature. Plant life adapts either by being an "avoider" -- a saguaro cactus has waxy braches to hold water to get through droughts; a "confronter" -- an ocotillo cactus loses its leaves, then re-grows them as soon as it rains; or an "acceptor" -- a creosote bush grows long root systems so it can survive for long dry periods.

A stately saguaro cactus can live for 175 - 200 years, and produce 40 million seeds in a lifetime. Few will survive to adulthood. The odds are clearly against it. Early life goes into making roots, because above-ground growth, flowers and branches are considered "luxuries" compared to being prepared to capture all the moisture there is. And by adulthood, a saguaro can absorb 200 gallons of water in its accordion pleated trunk and branches, enough to last it a year.

Over 50 species of cacti live in the Sonoran desert, and a host of well-adapted birds, lizards, rodents and other flowering plants, all woven together in a tapestry of life as delicate as it is tough. But at sunrise or sunset, the constant dust in the air creates gorgeous light, and conditions kinder to the Sonoran’s animal life, for at these times moderate temperatures and the possibility of moisture in the form of dew offer hope, a welcome respite from the noonday heat.