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Desert Diary
Ecology/Roadway Green


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Next time you're out driving, pay attention to the differences in the vegetation next to the road as compared to that farther away. In most places and times in the Chihuahuan Desert, the differences are dramatic. There's two common reasons for the differences. For one, the shoulders of a roadway commonly have been disturbed by highway maintenance designed to keep vegetation down and preserve proper drainage off of the road. The result is that pioneer plants often find the habitat virtually competition free and a perfect place to grow. Of course, keep in mind that pioneer plants often are what the layperson calls weeds, such as the alien tumbleweed.

There's another reason for differences, though. Plants near the roadway are better watered than those outside of its influence. The reason is simple: water falling on asphalt or cement cannot sink in, and in a properly designed highway runs off to the edge of the road. Watch the creosotebushes next time you travel—in a dry year, those next to the road are larger and by far the greener.
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Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.

Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.