Why Is The Ground Brown

April 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: 'Resurrection plants' offer hope as climate turns hostile

Related Stories

Seven case studies in carbon and climate

November 13, 2015

Every part of the mosaic of Earth's surface—ocean and land, Arctic and tropics, forest and grassland—absorbs and releases carbon in a different way. Wild-card events such as massive wildfires and drought complicate the ...

A breathing planet, off balance

November 13, 2015

Earth's oceans and land cover are doing us a favor. As people burn fossil fuels and clear forests, only half of the carbon dioxide released stays in the atmosphere, warming and altering Earth's climate. The other half is ...

Mars will come to fear my botany powers

November 10, 2015

NASA seems to believe that making space habitable will require more finesse than Elon Musk's "let's nuke Mars" plan, and has funded a couple of synbio projects which seek to provide "the means to produce food, medical supplies ...

China's biodiversity declines as human demands grow

November 12, 2015

Since 1970, China's terrestrial vertebrates have declined by half, while the nation's Ecological Footprint has more than doubled, reveals WWF's Living Planet Report China, 2015, a flagship research report on the country's ...

Recommended for you

'Material universe' yields surprising new particle

November 25, 2015

An international team of researchers has predicted the existence of a new type of particle called the type-II Weyl fermion in metallic materials. When subjected to a magnetic field, the materials containing the particle act ...

CERN collides heavy nuclei at new record high energy

November 25, 2015

The world's most powerful accelerator, the 27 km long Large Hadron Collider (LHC) operating at CERN in Geneva established collisions between lead nuclei, this morning, at the highest energies ever. The LHC has been colliding ...

New gene map reveals cancer's Achilles heel

November 25, 2015

Scientists have mapped out the genes that keep our cells alive, creating a long-awaited foothold for understanding how our genome works and which genes are crucial in disease like cancer.

A blue, neptune-size exoplanet around a red dwarf star

November 25, 2015

A team of astronomers have used the LCOGT network to detect light scattered by tiny particles (called Rayleigh scattering), through the atmosphere of a Neptune-size transiting exoplanet. This suggests a blue sky on this world ...


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.