Rocky Mountain National Park - Parks and Valleys

The word "park" has a special meaning in Colorado: it describes a low, open pocket of land surrounded by protective peaks. Because it is level, it has water -- a lake, a stream, a swampy patch -- fed by mountain rills; and because it has water, it is a local point for life. Mule deer and elk feed in parks when higher elevations are winter-locked. Mountain bluebirds and broad-tailed hummingbirds arrive to nest in early spring and linger well into autumn, among evening grosbeaks, pygmy nuthatches, and other permanent inhabitants. Scurrying through the summer, chipmunks and the larger Wyoming ground squirrels may fall prey to plummeting golden eagles that soar sharp-eyed high above the summits.

Flourishing around the parks, and on other lowland slopes on the comparatively dry eastern side of the Great Divide, are ponderosa forests, spacious and sunny because each tree's thirsty, spreading roots allow little nearby competition for moisture. The underbrush that does manage to become established is periodically cleared out by low ground fires, from which the mature trees are themselves protected by the armor plating of their thick, russet bark. The bright, grassy floors of these forests are carpeted in summer with multicolored mosaics of wildflowers; the branches above are the year-round home of North America's showiest squirrels, the tassel-eared Aberts. Nearly housecat-sized, with flowing tails and large, tufted ears, Abert squirrels have glossy coats that may range in color from solid black to dark rusty brown, or they may wear any of several elegant variations. They rarely venture far from the stately ponderosas, living on the seeds in summer and on new-growth twigs in winter.

When forest fires burn fiercely enough to wipe out the ponderosas -- or the denser forests of Douglas fir that flourish on north-facing slopes and in valleys west of the Great Divide -- the desolated land is soon covered over with such pioneering wildflowers as fireweed and goldenrod. Close behind come quaking aspens.

Wherever a stand of aspen grows, beavers are likely to find it. The layer beneath the white bark is one of their favorite foods, and the soft trunks their preferred building material. Entire aspen stands can be leveled in a few beaver generations; sometimes the industrious rodents build canals to float the fallen trees where they want them. But aspens grow very quickly from their roots, and each cut trunk is soon replaced by two or three new ones.

One reason that aspens grow so fast is that they are extremely efficient gatherers of solar energy. Unlike the leaves of most trees, an aspen leaf is equipped on both sides with chlorophyll factories that use the energy of the sun to manufacture food. And because the leafstalks are flat, the leaves turn from side to side with every change of the breeze, always presenting a working surface to the sun. The resultant quivering rustle is the reason that the trees are called quaking aspens.

In the fall, when the chlorophyll factories shut down and the leaves' natural pigments of yellow, red, and orange are no longer masked by green, the aspens become resplendent. The color may last only a few days before it is stripped by winds from the mountain heights, but while it lasts, the aspen gold -- in combination with the incomparably beautiful Colorado blue spruce that crowds the banks of streams and lakes, its perfectly conical form ashimmer all year round with the color of the sky -- is the glory of the Rockies.