Rocky Mountain National Park - The Vertical Landscape

Tenuous as it is on the summits, life's hold is firm below the timberline -- on mountain slopes, in deep valleys, and across the broad lowland glades called parks. Because every 1,000-foot rise in elevation is the equivalent of about 600 miles of northward travel, the 1¼-mile drop from the park's highest mountaintop to its deepest valley is like an overland trek of more than 2,000 miles. Along the way -- as though all that geography had been compressed and stood on end -- one passes through several zones of life that band the mountains. Each imposes its own requirements for survival and each, therefore, is home to different kinds of living things. Cutting through these zones are lush watercourses, dry rockslides, stripes of destruction where fire has licked from below or avalanches have slashed from above, and other variations that make a patchwork of life's neatly layered pattern.

Downward from the timberline to about 9,000 feet is a mountain-slope world, where the spruce, fir, and pine species that grow dwarfish and stunted in the krummholz stand tall and erect in cool, shady forests. Snow, blown from the mountaintops, accumulates among them, and some deep piles do not melt away until late July. These snowbanks, marked by the large tracks of snowshoe hares, are the reservoirs of the mountain slopes, the fountains of life for things below. Slowly melting, they feed clear mountain streams that tumble laughingly down into lakes and rushing valley rivers.

Some drops of this water will eventually reach the Pacific Ocean, by way of the Colorado River; others will be carried eastward to the Mississippi and thence to the Gulf of Mexico. The boundary is the Great Divide -- the high spine of the continent -- that winds northward along the park's peaks and ridges. Air comes from the west and, as it rises toward the divide, its moisture condenses; hence the western slopes get much more rain and snow than those on the east.

Interspersed among the forests of spruce and fir are stands of lodgeple pine, so named because Indians came up from the plains to cut the straight, slender trunks for use as tepee poles. On upper slopes, the lodgepoles are a sign that a forest fire raged in the not too distant past. An integral part of the lodgepole life cycle, fire sweeps easily through the thin-barked trees, killing most of them. But immolation is the means by which the lodgepoles proliferate. Their cones open only in the presence of such intense heat; and so, not long after a fire has reduced a lodgepole stand to a wasteland of blackened trunks, a seed storm rains down. A new stand is begun before the ruin cools.

Eventually, on moist upper slopes, the shade-loving spruced and subalpine firs take root beneath the sheltering lodgepoles. Over the decades they gain height, finally overtopping the lodgepoles and shading them out. But lower down, on drier slopes near the 9,000 feet level, the lodgepoles dominate, waiting like living tinder piles for lightning to set off new life-giving fires. Licking upslope into the spruce-fir forests, the fires clear fresh land for temporary lodgepole incursions.

Diminutive red squirrels chatter in the branches of all the forests in this mountain-slope zone, roundly cursing hikers and other trespassers. More easily heard than seen, they reveal their presence by "squirrel kitchens," piles of cone scales that accumulate beneath the branches where they have ripped cones apart to get the seeds. Sometimes they store unopened cones in the cool, damp interiors of such piles to preserve them; lodgepole cones, however, are just dumped on the ground, for they remain closed without special storage.