Why Is The Ground Brown

Apr 12, 2006

Ecologists have long asked, Why is the world green? In other words, why aren't herbivores, such as insects and grazing animals, more successful at eating the world's green leaves, also known as plant biomass?

In the May 2006 issue of American Naturalist, Steven D. Allison (University of California, Irvine) asks the same questions a different way: Why is the ground brown? Why don't the organisms that break down the carbon in the soil consume it all?

Some of the same ecological factors make the world green and the ground brown, especially the carbon in plant material, the role of herbivores and decomposer organisms in consuming that carbon, and the role of predators in eating the consumers of the carbon. As it turns out, as Allison observes, "the chemical structure of soil carbon makes it far more difficult to consume than plant carbon."

There is about three times as much carbon in soil than in plant biomass. In addition, minerals in the soil can block decomposers from feeding on soil carbon. Allison also points out that most decomposers are of relatively small size compared to the animals eating green leaves.

"Instead of digesting material in their guts, decomposers depend on enzymes to partially digest their food sources outside their bodies," Allison explains. "This strategy is a major constraint on the breakdown of soil carbon that helps make the ground brown."

Founded in 1867, The American Naturalist is one of the world's most renowned, peer-reviewed publications in ecology, evolution, and population and integrative biology research. AN emphasizes sophisticated methodologies and innovative theoretical syntheses--all in an effort to advance the knowledge of organic evolution and other broad biological principles.

Steven D. Allison "Brown ground: a soil carbon analog for the green world hypothesis," The American Naturalist 167:5.

Copyright 2006 by Space Daily, Distributed United Press International

Explore further: NASA issues 'remastered' view of Jupiter's moon Europa

add to favorites email to friend print save as pdf

Related Stories

Research helps raise awareness of human trafficking

10 minutes ago

Human trafficking –– or the control, ownership and sale of another human being for monetary gain –– was a common occurrence centuries ago, but many believe it doesn't exist in this day and age and not in this country.

Recommended for you

NASA issues 'remastered' view of Jupiter's moon Europa

Nov 21, 2014

(Phys.org) —Scientists have produced a new version of what is perhaps NASA's best view of Jupiter's ice-covered moon, Europa. The mosaic of color images was obtained in the late 1990s by NASA's Galileo ...

European space plane set for February launch

Nov 21, 2014

Europe's first-ever "space plane" will be launched on February 11 next year, rocket firm Arianespace said Friday after a three-month delay to fine-tune the mission flight plan.

Space station rarity: Two women on long-term crew

Nov 21, 2014

For the 21st-century spacewoman, gender is a subject often best ignored. After years of training for their first space mission, the last thing Samantha Cristoforetti and Elana Serova want to dwell on is the ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.