Measuring Arizona.

MOVE OVER, FLORIDA. NOW THE DESERT STATE CAN BOAST CANYONS. CACTI - AND MORE NEW CHAMPION TREES THAN ANYONE ELSE.

Arizona

Where mineral mountains crisscross basins bare of green. Where rattlesnakes, scorpions, and gila monsters seek shelter from the sun, and the law of the land is to ration water. A land far removed from the towering big tree groves of the Sierra Nevada and the wet slopes of the Pacific Northwest.

Given that, it may surprise you that Arizona claims 58 crowns in the 1998-99 National Register of Big Trees. Thirty are new or reinstated champs, giving Arizona top status for new listings and bumping Florida, which previously held that title. What is it about the desert state that gives it this distinction?

Ironically, the same geography, topography, and climate that make Arizona such a challenging habitat to live in also are responsible for its multitude of champions. The southwestern third of the state shares the Sonoran Desert with California and Mexico. The Sonoran is one of the Southwest's three great deserts but an unusual one because it has two rainy seasons. Rainy, of course, is a relative term here since annual precipitation averages less than 10 inches. It's also subtropical. Species have evolved here that live nowhere else.

"We've got probably 118 species of native trees," says Robert Zahner, coordinator of the Arizona Register of Big Trees. "Approximately half of those are endemic to the desert Southwest, which means they occur only in southwest New Mexico, southern Arizona, and southeast California, and also, of course, in Sonora, Mexico." Nineteen species are endemic to Arizona, which means their national champions must be in Arizona, he says.

A retired forestry professor, Zahner has been hiking the state's backcountry mountains and deserts for 25 years. When he first came to Arizona, he made it his hobby to learn all the plant species, especially the trees.

It's an avocation he shares with his wife, Glenda, and together they have discovered 16 national champions. In some cases the task was relatively easy. The Ajo oak (Quercus turbinella var. ajoensis) occurs only in the Ajo Mountains in Organ Pipe Cactus National Monument on the Mexican border, and there is only one known grove in the entire world.

Harder to find was the elephant-tree (Bursera microphylla), whose gray-white bark and odd-shaped branches give it an elephant-like appearance. The tree grows 40 or 50 feet high in parts of Mexico, but the specimens in this country rarely qualify as trees. Sensitive to cold, they are killed back to shrub size by the occasional frost that settles every three to five years on even the warmest spots in Arizona. Undiscovered in the U.S. until 1910, the elephant-tree was included in the list of species without champs in the 1996-97 National Register.

That challenge spurred Zahner's friend and fellow big tree hunter Ken Morrow to spend two days searching for a qualifier. He found it after following a jeep track 95 miles through the Cabeza Prieta Wildlife Refuge and into the Tinajas Altas Mountains of Yuma County.

"I walked up a rocky drainage of a canyon and sure enough among these big boulders on the hillside there looked to be a number of big elephant-trees," Morrow says. "We were just looking for something over 12 feet so that it would be eligible. There was one that was 12 feet tall with a few main trunks. This one had six or eight main stems. We added up the points [and] it wasn't real impressive, but it was a start."

As is the case with many desert species, neither the 31-point elephant-tree nor the 127-point Ajo oak is very large. But not all Arizona's titleholders are little big trees. Consider the champion Fremont cottonwood (Populus fremontii var. fremontii) in Santa Cruz County. With a circumference of 42 feet, Zahner says it has by far the biggest trunk he's seen on a nonconiferous tree. Weighing in at 623 points, it's a big tree by any standards and, in fact, may be the largest cottonwood in the world.

Arizona's cottonwood was the official national champ from 1970 until 1986, when a specimen with more points was nominated in New Mexico. No one could remember the Arizona tree's exact location to remeasure it, so the New Mexico tree reigned until 1995, when a big tree hunter from Iowa called Zahner to say he thought he'd found it. Arizona's contender had grown significantly since its last measurement in 1970 and took back its tide in this edition of the Register.

"It really was the champion all along, but since it was not periodically remeasured, we didn't realize it. Now we've got our champion back," says Zahner.

If it sounds like there's competition among states for champion status, that's because there is. Another crown recently reclaimed from New Mexico is that of the Arizona walnut (Juglans major). In that case, the New Mexico champ had two trunks that split below chest level. Zahner realized the tree was measured incorrectly when he saw its picture. (The Register stipulates the largest trunk must be measured 4 1/2 feet above the ground.)

"It is a kind of rivalry," admits Morrow, adding the competition may be fiercer on Arizona's side because the state has such an active group of hunters. He adds they particularly want to have the biggest trees with names containing the word Arizona, such as the Arizona walnut. "We do feel if we can find it in Arizona it makes us proud."

The search is underway for a contender that can achieve champion status for the state tree, the blue paloverde (Cercidium floridum). The current national champ of this short-lived species resides in California, and Morrow says it has not been seen in 20 years.

Morrow is a horticulturist who runs an ornamental desert tree farm near Phoenix. He became interested in big trees when he found he couldn't answer customers' questions about how large the trees he sold could grow. He found the answers in a public library within the pages of the National Register of Big Trees. He also found Zahner's name and contacted him, and it wasn't long before Zahner was sending Morrow on expeditions to remeasure trees and follow new leads in his part of the state.

All this activity and competition also helps explain why there are so many national champions in Arizona. The desert state had only 20 champs in 1992 when Zahner helped recruit a committee to organize Arizona's Register and began an intensive statewide search for specimens.

The first hunt was for Arizona's undisputed monarch, the saguaro (pronounced su-wahr-ro) or giant cactus (Cereus giganteus). Countless Hollywood westerns feature this slow-growing desert icon as a backdrop.

Its fragrant, white waxy bloom is the state flower. The Papago Indians traditionally ate the saguaro's fruit and used its wooden ribs to build their homes. At the age of 14 it may be only six or seven inches tall. The biggest trees. with 40 to 50 "arms" or branches and a height of nearly 50 feet, can live 250 years and store up to nine tons of water.

A lightning strike recently killed the larger of two national co-champions in the Vulture Mountains. That spurred the committee to conduct a public outreach campaign. Newspaper stories prompted dozens of nominations. and Morrow measured all promising leads. The outcome: Five Candidates fell within the required five points of the current champ, resulting in a six-way tie. The biggest saguaro totals 130 points: the tallest stands five stories high.

"They seem to attain more or less the same maximum size before something happens to them." says Morrow. Tall and top-heavy, they're vulnerable to high winds and storms. Desert creatures such as owls and woodpeckers favor them as homes. and the holes they bore into the trunk of a saguaro can make it susceptible to a bacterial necrosis that eventually kills it.

"Now I'm not saying there's not a bigger one," adds Morrow. "We've heard reports of one in the Guinness Book of World Records that's nearly 60 feet tall. I haven't tracked it down yet: it's on my list of things to do this winter."

And so the search continues in Arizona, where a little bit of the Wild West remains. It's wide-open territory for tree hunters. No matter how big the existing champ, there's always the possibility that around the bend in a hidden canyon there lurks a bigger champion.

RELATED ARTICLE: A PLACE FOR local giants

Want to start a big tree register for your city, town, or county? Unsure how to start? The most important thing to remember is why you're doing it: to get your community interested and excited about locating and protecting big trees. Your efforts will get people looking for and appreciating the largest and oldest living things on earth and all their accompanying benefits.

Get organized before you start accepting nominations. Here are some suggestions:

* Decide which species are eligible. It's best to be consistent with the national program so your local champs have a chance to become national champs. AMERICAN FORESTS' National Register of Big Trees recognizes 823 native and naturalized species. You may want to allow some popular local plantings too.

* Decide how to measure trees. The point system in the national ! Register is a weighted formula that allows for consistent comparisons. (See page 13 for details.)

* Develop a brochure. Explain why big trees are important, what geographic region and species are eligible, and how to measure and nominate trees. Keep it simple to encourage participation. You may want to design nomination forms and certificates to recognize big tree owners and nominators.

* Choose a coordinator. This can be someone from your local parks & recreation or public works department, or a local forester or arborist. The individual selected should know enough about trees to verify species and measurements.

* Document your trees. Use a simple computer database or index card file to record species, measurements, locations; nominators, and property owners. Photographs are helpful.

* Conduct outreach. Publicize your program in local newspapers and on TV and radio. Talk to garden clubs, conservation groups, end civic organizations. Then get ready for nominations.

* Publish your register. It can be self-published or sponsored by a local newspaper, chamber of commerce, or other organization. AMERICAN FORESTS' National Register of Big Trees is published biennially.

- Craig Noble

Craig Noble is AMERICAN FORESTS' communications specialist and an admirer of western trees.