Plant-and-Animal Communities (continued)

Groves and Grasslands: The Prairie Sea

There is something about spring on the prairie that gets me up before dawn. I like to watch the seasons change their guard over the landscape, from the wintry cold of pre-dawn dark to the spring-scented morning air to the hot summer-foretaste of the noon May sun.

Hoarfrost surrounds these patches of pasqueflowers, blue goblets on downy stems. On this windless night, frost has formed everywhere, reclaiming for a time its vast winter range, sparkling over the green handiworks of spring.

But the god of the growing grasslands is the sun, and it now proclaims itself, stretching out to make the mountains shine. With its assault the frost collapses, becoming bright beads on grass tip and leaf joint by which a beetle might refresh itself.

Spring is best perceived ant-level, at its ground beginnings, where the bright yellow-green tips of new grass shoots reclaim the winter-blighted land, I look closely at a drag line of spider silk; a necklace of dewdrops slides down, collects to a moment's greatness, in which I briefly see a curved horizon, the morning sunburst, and myself, before it falls away.

Getting up from my prone position, my belly damp from the prairie earth, I startle a whitetail jackrabbit; bounding high, it zig-zags off. The commotion disturbs a distant badger, which faces about from its diggings to confront danger in whatever form it might take. It swings its snout to scent the air. Somewhat uncertainly, it returns to the business of hunting, then hesitates, swings about once more and waits, myopic, patient.

Satisfied at last, the spurt of the now distant rabbit lost in its brain, the creature snorts a defiance at the mystery and resumes its morning gopher hunt.

Overhead a marsh hawk skims past, its flight erratic as a butterfly's. Far away a magpie rattles at the passing hawk and takes flight, briefly flashing black and white.

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.

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.