# 9.7: Competition

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Examples of competition seem both more subtle and more ordinary than examples of mutualism and predation. But competition is pervasive.

North America has many ecosystems—the tundra of the Arctic, the deserts of the Southwest, the giant conifers of the Pacific Northwest—but the three largest ecosystems merge in a triple ecotone in the Upper Midwest, an area which exemplifies competition among plants. Here, the needle-leaf forests stretch north to the arctic, the broad-leaf forests extend east to the Atlantic, and the prairies’ amber waves of grain ﬂow west to the Rockies. Figure $$\PageIndex{1}$$ shows a whirlpool of competition at this broad triple ecotone. White pines stand tall above the deciduous trees in the background, with Big Bluestem and other native prairie grasses setting seed in the foreground. Staghorn Sumac in red fall colors tries to hold its own in the middle, with pines invading behind it. Leaves of Bur Oak are browning for the oncoming winter.

While it may seem a peaceful scene, for the plants it is a scene of intense competition for their very existence. Fire is a foe of trees (Figure $$\PageIndex{1}$$ right), killing many instantly, and thus favoring grasses and prairie flowers. Times of moister conditions allow trees to reenter the grasslands, eventually shading the grassland vegetation to death if the moisture persists. But complexities of weather and climate have kept this competitive tension zone intact for thousands of years, with no group permanently gaining the competitive advantage.

This page titled 9.7: Competition is shared under a CC BY-NC 4.0 license and was authored, remixed, and/or curated by Clarence Lehman, Shelby Loberg, & Adam Clark (University of Minnesota Libraries Publishing) via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.