Hosted by Sandra Tsing Loh, The Loh Down on Science is a fun way to get your daily dose of science plus a dash of humor in less than two minutes.
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Tree Chimneys

A botanical source of methane.

Never mind those Febreze fantasies of fresh-smelling forests. In real life? Trees pass gas.

This is Sandra Tsing Loh with The Loh Down on Science.

I mean the greenhouse gas methane, or CH4. Recently, methane was detected in unexpected abundance in tropical rainforests. While bacteria living in damp soil are known to produce methane, trees typically aren't. What's up?

Curious, physicist Andrew Rice of Portland State University created mini wetlands in a greenhouse. He then monitored methane concentrations both above and below ground. As expected, much of the methane produced by soil-dwelling microbes stayed underground. A small amount was broken down chemically as it bubbled to the surface.

Then Rice planted ash, cottonwood, and willow trees in the soggy soil. Below-ground methane levels dropped; above-ground levels soared!

Were trees sucking up methane with their roots and fizzing it out through their leaves?

Seems so. Why? Nobody knows.

Theoretically, these "living smokestacks" could be generating 10 percent of the 2 million tons of methane entering our atmosphere daily. Then again, humans - with our fossil fuels, large-scale cattle farming, and vast cultivated wetlands - generate 50 percent.

Whew! Better get an army of those hanging little air fresheners! Pine-tree shaped.

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