Airdate: Feb 04, 2004
Scientist: Dr. J. Mark Dangerfield
Soil Litter - The Food Web
There's a dense population under our feet that sustains life for us above the ground.
Soil Litter: The Food Web
Ambiance: Leaf walk
Ever wonder what happens to all the millions of leaves that fell to earth every Autumn? Well, as they decay, they make up the base of an extensive food web that reaches far down into the soil beneath us. I'm Jim Metzner, and this is the Pulse of the Planet. Dr. Mark Dangerfield is a soil biologist at MacQuarie University in New South Wales, Australia.
"In a temperate climate, when the leaf falls on the ground, it may only take a few months before that leaf is broken down and mixed into the soil, because what happens is all the organisms chase that leaf and they start to eat it. There's a succession of organisms that eat that material, as it gets smaller and smaller."
Those tiny organisms in the soil dismantle dead plant material releasing carbon, nitrogen and other elements locked inside. The process begins almost as soon as a leaf hits the ground.
"When a leaf falls, maybe the first thing that happens to it is that it starts to get a coating of microbes on the surface. Then what might happen is a beetle might come along and chew a bit of that leaf, or an earthworm might come along and pull some of that leaf down into the soil. When it gets smaller now, that small patch may be attacked by new microbial organisms, different ones to the ones that started at the surface. And then those microbial organisms themselves may be eaten by other organisms in the soil; there's a whole web, an interaction of these organisms, and what we don't know, is which species are involved in those interactions. Which ones actually make these things happen, and which ones are important to keep that process moving."
Biologists like Mark Dangerfield continue to identify new life forms that are being discovered in the soil layer almost every day. Well they believe it's possible that the variety of life beneath our feet could match anything that's been seen above ground.
Pulse of the Planet is presented with support provided by the National Science Foundation. I'm Jim Metzner.