What’s Below Is Just As Important As What’s Above

Creatures, such as worms and mites, help prevent erosion and stabilize the soil.

WASHINGTON — Scientists whose job is to grub around in mud and dirt say that what lies hidden under the ground is as important to life as what can be seen above the Earth’s surface.

Many vital services that people take for granted are provided by tiny animals and invisible microbes in "the unseen worlds beneath our feet," said Diana Wall, an ecologist at Colorado State University in Fort Collins.

Bacteria, fungi, mites, earthworms and one-celled organisms form a vast, teeming underground population that is surprisingly little understood. These subsurface creatures provide essential elements such as carbon, nitrogen and phosphorus to plants growing in the sun and air above. They distribute water and remove waste.

"Ninety percent of the things in the soil we don’t know anything about," said Valerie Behan-Pelletier, an expert on soil mites at the Canadian Ministry of Agriculture and Agri-Food.

This sunless underworld is "one of last great frontiers of biological research," Behan-Pelletier told a panel on "Biodiversity in Mud and Dirt" at a February meeting of the American Association for the Advancement of Science.

"Most of the things we need in life are found in the soil," she said. "They don’t need us — we need them."

Wall said they help prevent erosion and stabilize the soil by "gluing" little particles together to form bigger ones. She compared the process to ancient Egyptian slaves building the pyramids by piling up rocks, one by one.

Microscopic trash collectors also clean the surface of the Earth so it’s not buried under mountains of dead animals and vegetation.

"Microbes rip, tear, shred, dissolve and transform wastes and dead bodies," Wall said.

Depending on the depth of the soil, as many as 1,000 earthworms may exist beneath a plot no bigger than a square yard, Wall said. One gram of soil or muck (there are 28 grams in an ounce) can contain up to 100 million bacteria, a million fungi and 1,000 algae, she added.

Alan Covich, the director of the Institute of Ecology at the University of Georgia in Athens, said, "There are an awful lot of things going on that are hard to see — the production of goods and services that people benefit from but don’t think about.

"These life-support services are provided at no charge seven days a week," he said.

Harold Mooney, a biologist and expert on root growth at Stanford University, said a new coalition of researchers had been forming to study the underground world.

"It’s crucial to look under the surface of the soil and water and see what’s happening," said Mooney, who moderated the "Mud and Dirt" panel.

Scientists who specialize in the underworld worry about damage to the Earth’s crust from pollution, deforestation, loss of wetlands and invasions of alien species. Rebuilding damaged soil is a slow, uncertain process.

"It takes longer to restore biodiversity below the surface than above the surface," Wall said.

About mites:

www.tolweb.org/tree?group=Acari  

About earthworms:

www.ibiblio.org/pub/academic/agriculture/sustainable_agriculture/faqs/earthworm-faq.html