STRAIGHT UP

when it comes to plants and trees, arizona is probably best known for its saguaros, but it's also home to the largest ponderosa-pine forest on the continent. the big trees, which can live to be 500 years old, are everywhere in the high country. you can't miss them. just look straight up - as much as 130 feet into the air. think pinus ponderosa smells like vanilla. some people say butterscotch or orange, but most agree it's something delicious. scratch the ponderosa's trunk, and the scent you'll smell is something you won't forget. you don't forget the majesty of the tree, either: its tall, straight trunk; the distinctive reddish-yellow, rectangular plates set apart by dark furrows in a mature tree's bark; its graceful long needles, waving in a breeze; and its elegant crown and sweeping middle branches. it is, for me, the epitome of pine. to see the tree - to take in its height and the straightness of its trunk one needs to stand back, but to fully sense it, you'll need to get close. because ponderosas demand space, you often can do both. unwilling to huddle together as other trees do, ponderosas prefer to grow in park-like groves. their roots, which spread underground until they meet the spreading roots of other ponderosas, keep other trees at a distance. the space created by the tree invites light. in stands of ponderosas, sun streams onto the forest floor. it glitters on the trees' needles. it invites you to wander through, to linger.

ponderosas live for 250 to 500 years, growing 60 to 130 feet tall. they shed lower limbs as they age, exposing the sturdy straightness of the trunk while increasing the sense of space surrounding the tree. the plates of reddish-yellow bark on mature trees (the bark on young trees is dark gray, with small scales) can grow to 4 or 5 feet long, with deep, dark furrows between them. the more the bark thickens with age, the more fire-resistant the tree becomes. long needles grow two to five to a fascicle, or tuft. the tree's size, its great spread of branches and the magnificence of its needles probably influenced scottish botanist david douglas to call it “ponderosa.” douglas first saw the big pine in the northwest in 1826. more than 20 years earlier, meriwether lewis had collected a specimen of the same tree — calling it “longleaf pine” in his notes - as the lewis and clark expedition traveled through what is now idaho on its homeward journey. unfortunately, lewis' natural-history notes were ignored when the expedition journals were published, and his own plans to publish them never came to fruition.

the ponderosa grows throughout the west, from british columbia to mexico. it's typically larger on the coast, where it receives more moisture. it's the state tree of montana and a signature tree on the colorado plateau, where extensive ponderosa forests are found at elevations of 6,000 to 8,000 feet. in arizona, on the kaibab plateau and the mogollon rim, nearly pure stands of ponderosas cover tens of thousands of acres. the forest stretching from the san francisco peaks to the white mountains is the largest ponderosa-pine forest on the continent.

arizona offers ponderosas the kind of country they love: a temperate zone; an essentially level landscape with enough annual moisture for growth; and dry seasons in spring and autumn, so the trees aren't sitting in water. in a normal year (if there remains such a thing), the spring dry period is broken in july by almost-daily thunderstorms. winter usually brings snow that, upon melting in spring, sinks into the subsoil and down to the roots.

forest fires are normal in the west, and the ponderosa evolved with frequent fire. low-intensity fires every few years helped maintain large, open stands of ponderosas by burning seedlings but only scarring mature trees, which are naturally resistant to fire. even if the bark is blackened by a fire, the tree remains fully alive. in the open stands that ponderosas prefer, a fire started by a lightning strike will not spread to other trees. but dense forests, resulting from years of fire suppression and old logging practices, are more volatile. fire conditions become extreme when density combines with drought and high wind. hope for turning around extreme conditions in arizona's forests lies in the four forest restoration initiative, which aims to restore natural conditions in the kaibab, coconino, tonto and apache-sitgreaves national forests via thinning and fire.

I'm not thinking about fire as i walk through the forest on the kaibab plateau, home to the largest contiguous stand of old-growth ponderosas in the southwest. unlike the mogollon rim, which was heavily logged, the north kaibab, too far from the railroad, was mostly spared, even though ponderosas were, and are, a valuable lumber crop.

I'm not thinking about logging, either. Perhaps I'm not even thinking. An Abert's squirrel with tasseled ears chatters as I walk beneath the tree limb where it sits. This squirrel's life is tied to the ponderosa, which offers it shelter and food (it eats ponderosa seeds and the tree's cambium layer), and the squirrels seem to be all over this forest. There are mountain lions and mule deer here, too, although I'm not seeing either on this walk. But I'm here to experience the trees, having been drawn into the forest on a drive along U.S. Route 89A from Fredonia. Abert's squirrel aside, I love the silence that glides down the light entering the forest, a silence as palpable as light. The forest floor offers easy walking. The trees shelter me. I'm happy here.