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: UI researchers launch rockets in search of unseen parts of universe

add to favorites email to friend print save as pdf

Related Stories

New Hampshire bill requires cursive, multiplication tables

3 hours ago

As schools adopt new education standards and rely more on computers in the classroom, a group of New Hampshire senators want to make sure the basics of learning cursive and multiplication tables don't get left behind.

Recommended for you

Scanning Earth, saving lives

13 hours ago

A high-speed camera for monitoring vegetation from space and combating famine in Africa is being adapted to spot changes in human skin cells, invisible to the naked eye, to help diagnose skin diseases like ...

How far back are we looking in time?

14 hours ago

The Universe is a magic time window, allowing us to peer into the past. The further out we look, the further back in time we see. Despite our brains telling us things we see happen at the instant we view ...

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.