The Crown of the Continent
Ecosystem Education Consortium
C.O.C.E.E.C.

What is an ecosystem?

An ecosystem is commonly defined as " An ecological community, together with its environment, functioning as a unit."

An ecosystem includes physical and biological components and natural processes - not merely the food chain of plants and animals, but also non-living components, such as the types of rocks, the soil, the natural chemistry of the water, the movement of weather systems, precipitation and climate, and the cycle of energy, flowing from sun, to grass, to animals, to predators, and back to the Earth.

A pond, a meadow, or even a rotten log can be considered as a distinct ecosystem, but they are also parts of larger ecosystems, such as a forest or a watershed. In a similar way, forests and watershed ecosystems are also parts of even larger ecosystems - entire mountain ranges, or even continents. On one scale, the Earth itself can be considered a distinct ecosystem, because all its parts function interdependently. But even the whole planet is not a complete ecological unit, because the Earth depends on the sun for energy.

Consider the ecosystem of a mountain lake. Its non-living components include the snowpack and the rock basin that collects the water from its annual snow melt and runoff. In addition to melting the snow, sunlight provides energy to microscopic plankton. The plankton feeds tiny invertebrates in the water, that, along with the temperature and chemistry of the lake, help determine how much life the water can support. The plankton are fed upon by small fish, which in turn are eaten by larger fish like bull trout. On a slightly expanded level, the lake ecosystem includes the tributary streams where bull trout spawn, and it also includies predators, such as river otters and human anglers, that eat bulltrout.

But the lake's ecosystem is not confined even to its watershed. Bald eagles and common loons may raise their young at the lake, but in winter those birds may migrate to Mexico or Florida. So a mountain lake in the Crown of the Continent is a small part of a continent-wide ecosystem.

Ecosystems can be considered on a microscopic, a continental, or even a cosmic scale. For human convenience in description, we define ecosystems and put borders around them. But such boundaries are always imperfect and permeable.

Political boundaries further complicate our understanding of an ecosystem. Grizzly bears and songbirds, for example, are dual citizens, roaming freely over international borders. Radio-collared wolves have been tracked from Montana to Alberta and British Columbia and back. In one jurisdiction, a wolf is a protected, endangered species, in another, a hunter's trophy, and in another, an agricultural pest.

A grizzly bear may live in the Belly River drainage of Glacier National Park, eating riverside grasses in the spring, then moving upslope to feed on huckleberries in summer, before digging a hibernation den in the high mountains in late autumn. This bear may never leave the mountains, but its ecosystem reaches far beyond the animal's home range. In summer, the bear may feed on thousands of army cutworm moths, which retreat to the cool, high mountains from distant farm lands where they hatch. So the ecosystem to which the grizzly belongs includes farms hundreds of kilometers away from the bears themselves.

An even more dramatic example is the Swainson's hawk, frequently seen hunting small rodents and large insects on the Rocky Mountain Front. This bird breeds in Montana and Alberta, where it feeds mainly on rodents. It migrates to the plains of Argentina during the North American winter. In Argentina, Swainson's hawks have died en masse from pesticide poisoning. Eventually, such die-offs could mean fewer Swainson's hawks - and more rodents - in the Crown of the Continent, a hemisphere away.

Ecosystems challenge us, because they force humans to think beyond the lines and categories by which we usually conceptualize and organize the world. Ecosystems are directly relevant to us, because we live in and are a component of the ecosystems that sustain our lives.