Part 3

■ It is easy to see only pieces in the natural puzzle—a badger throwing dirt, horned larks dipping into wind, black ants dragging the rosette of a dead spider—and be satisfied with the scattered scenes. But at last, to make it meaningful, we must complete the picture. There is that special joy in discovering larger schemes: green plants utilizing sunlight; a rabbit building its days at the plants’ expense; the falcon tearing the rabbit meat for its young; magpies picking at the fallen falcon; and then, in the end, all returning to the earth.

Here on the prairie, as in every plant-and-animal association, the ancient drama repeats itself over and over; the distant tundra is a drastically different stage with different actors, but the cycle is the same. Life depends upon the interaction of all its many forms. Unseen bacteria are as necessary to the land as green grass; the meadow vole and the coyote are as much a part of the prairie as the grasses.

The secret of life rests in the wonder of photosynthesis. Only green plants can manufacture food from the earth’s raw minerals. This is the vital first step upon which the great pyramid of animal and plant life is built. Using energy from the sun, green plants combine water and carbon dioxide to synthesize sugar, and give off oxygen as a by-product. The caterpillar takes its energy from the plant tissue, converting to protein the sugar and minerals in its body. The caterpillar is then food for a spider or other predator. A yellow warbler may take the spider and in turn be ambushed by the prairie falcon. Thus the energy produced by the plant travels through the food chain. When the prairie falcon dies, scavengers—including insects and other invertebrates, birds, and mammals—redistribute its wealth among themselves; the rest is decomposed by bacteria. Thus, eventually, the nutrients on which the plants depend return to the soil.

When we look at any living organism, whether it is plant, herbivore, carnivore, parasite, scavenger, or decomposer, we are soon made aware of its associations with other living things, each puzzle piece leading us to another and another. We begin to see a picture whole—the fox, meadow mouse, grasshopper, bunchgrass, and sparrow hawk—all interlocked.

Geologically speaking, grasslands are a recent development. As the Rocky Mountains were being uplifted, the prevailing warm, moist climate began to change. The rising mountain mass intercepted moisture-laden winds that blew in from the Pacific, creating a rain shadow that lengthened eastward as the mountains rose higher. A continental climate, characterized by severe winters and dry, wildfire summers gradually took shape, extinguishing the great forests that had grown across the continent’s interior. Herbaceous plants, which had been evolving amid the forests, inherited the land.

Unlike trees, grasses die back to the ground each winter, hoarding their life-germ beneath the protecting soil. Growing not from the tip but from the joints, grasses regenerate quickly after fire or grazing. Suspension of the normal metabolic processes enable the grasses to go dormant and thus survive periods of severe heat and drought.

Although the great prairie sea washes up against Glacier’s eastern boundary, with estuaries probing into the mountain valleys on the drier, south-facing slopes, the grassland community comprises less than 5 percent of the land area of Glacier National Park. This includes the puddles of prairie west of the Divide that interrupt the dense coniferous forests along the North Fork of the Flathead River.

From the pasqueflowers that bloom in early May to the asters and goldenrod of September, these summer-long gardens of grasses and flowers lean with the wind. Here are timothy, oatgrass and the bunchgrasses—rough fescue, bluebunch fescue, and bluebunch wheatgrass. Among the grasses bloom bitterroot, blue camas, lupine, gaillardia, balsamroot, cinquefoil, sticky geranium, and wild rose.

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Canopy Great Horned Owl Yellow-bellied Sapsucker Understory Flying Squirrel Shrub Layer Ruffed Grouse Herb Layer Red Squirrel Western Toad Forest Floor Shorttail Weasel Scavenging Insects Deer Mouse Garter Snake Soil Layer Ground Squirrel Earthworm Masked Shrew

Sun Green Plants Redback Vole Garter Snake Great Horned Owl Scavengers, Decomposers Soil

Conspicuous also are many insects—including grasshoppers; flies; ants, wasps and bees; butterflies and moths; bugs; and beetles—which fulfill important roles as herbivores, carnivores, and scavengers while also acting as pollinators for flowering plants and providing an abundant food source for other animals.

Below the ground are the tunnels. Burrowing is an important means of survival on the open prairie, and life underground is extensive. Some of the animals are rarely seen—the northern pocket gopher, for example, with a diet of underground insects, grubs, worms, and roots, spends most of its life tunneling just below the surface. Others, like the badger, leave their burrows during the day to dig for rodents. Most conspicuous of the burrowing animals in the park’s grasslands is the Columbian ground squirrel. Its alert upright stance has earned it the nickname “picket pin.” When danger approaches from the air or on land, its shrill alarm whistle passes the warning to others of its kind.

Where prairie and forest meet, a never-ending struggle for dominion is waged. The isolated patches of prairie that dot the North Fork Valley near Polebridge hold the great forest of the park’s northwest region at bay.

This broad valley, floored with coarse glacial outwash and terraced downward to the deep channel of the North Fork River, presents a graphic battleground between grass and tree. Lining the upper terraces, from which they glower down on the dry, well drained grass flats like a line of warriors, are the Douglas-fir, western larch, and ponderosa pine. Seedling trees continually invade the prairie. But most perish early, their shallow roots no match for the extensive root systems of the fast-growing, moisture-greedy grasses. If encouraged by a series of wet summers, however, the young lodgepoles quickly gain stature. They had made significant inroads at Big Prairie when the disastrously dry summer of 1967 killed most of these 15-year-old pioneer trees.

These North Fork grasslands and the immediately surrounding lodgepole pine forests are an important spring range. Deer, wapiti, and grizzly—and, in the wetter areas, moose—graze or browse here. And here, low on the western slopes of the Livingston Range, are the park’s only stands of ponderosa pine, a tree that prefers warm, dry habitats. As a result, at low elevations it often merges with the prairie community.

Groves of aspen colonize the eastern prairies in areas where there is sufficient water and protection from wind. These aspen parklands are important havens for animals. Wherever two differing communities interact, a phenomenon known as “edge effect” occurs. Here wildlife exists in abundance; the animals that favor forest cover mingle freely with those that prefer open areas. Aspen groves—supporting grasses, herbs, and shrubs beneath their thin canopies—are favored haunts for grouse, varying hare, deer, and wapiti, all of which find among the trees abundant food, shelter and concealment. Populations of insects, small mammals, and birds, which are high for the same reasons, attract a wide range of predators.

Isolated aspen groves are characteristically dome-shaped. Because aspens are capable of reproducing themselves vegetatively, the grove slowly expands outward from the parent tree. As a result, most of these groves are either exclusively male or exclusively female.

Since quick-growing aspens provide a bountiful food source for beaver, streams near these trees are often dammed by the rodents flooding lowlands and creating additional habitat in the form of willow flats. Another “edge effect” is established, attracting animals found near water. Waterfowl, marsh birds, moose, mink, muskrat, skunks, amphibians, and many others find such areas to their liking.

■ Before the appearance of the white man, these eastern prairies were a paradise for animals. Once, on the summit of Rising Wolf, light-headed from the climb and the view of endless prairie, I fancied that I saw that vast, undisturbed animal panorama spread before me.

Principally there were the bison, darkening the uneven land. Pronghorn bands flashed white on ridgetops, and moose moved through the long fingers of willow that extended eastward with the rivers. Caribou and wolves inhabited the shadows. Among vast cities of prairie dogs, swift fox and grizzly roamed. There were the clamorings of sandhill crane, and white clouds of trumpeter swans.

This land, endowed with a wealth of wild grass, wore its wilderness well.

The Forest

On Gunsight Pass, the rain lancing down, I found a sharpedged rock that split the continent in two. On both sides the rain rivulets ran down, a fraction of an inch determining the stream’s destination: Pacific or Atlantic.

The Continental Divide is a mighty barrier, a line of consequence that does more than determine watersheds. Its effect in Glacier is dramatic, as a look at the forests will reveal.

Obstructing the eastward flow of the moisture-laden Pacific winds, the Divide extracts a heavy annual tribute of precipitation from the air mass, forcing it to rise up the mountain chain, where it cools and condenses. Chief benefactors are the low western valleys, which respond with a lush growth of Pacific coastal-type forests.

The eastern valleys, however, deprived of abundant annual moisture and exposed to the wind and temperature ravages of the prairie’s continental climate, support a dramatically different kind of forest. Here Engelmann spruce and subalpine fir are the climax trees, contrasted with such trees as the western redcedar and western hemlock of the mild and moist McDonald valley.