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Airdate: Feb 02, 2004
Scientist: Dr. J. Mark Dangerfield

Soil Litter - Temperate Zones

Soil Litter - Temperate Zones
Climatic variances and geological history determine the biological make-up of soil.

Transcript:
Soil Litter - Temperate Zones

Music; Ambience: Dawn chorus, Ventana Wilderness

JM: Some biologists think of the Earth's entire soil layer is a kind of "biodiversity hot spot"- a place rich in plant and animal life. Now, you might think that soils in tropical climates like the Amazon would contain the most species, but it turns out there's actually more underground life per square inch in temperate regions such as Europe, China, and the United States. I'm Jim Metzner, and this is the Pulse of the Planet.

MD: "In temperate climates we see the most biodiversity because of the fact that the soil organic material stays there for longer."

JM: Dr. Mark Dangerfield is a soil biologist at MacQaurie University in New South Wales, Australia. He says that in a tropical environment, humidity and high temperatures help bacteria to quickly break down decaying matter in the soil. In a cooler climate, the same type of organic material simply lasts longer, and all that extra food provides more opportunity for new life to evolve.

"Because organic material stays longer in the soil there's potential for more organisms to be able to utilize it. They need different sorts of skills and techniques to be able to get benefit from that material."

But it's not just the cooler climate that makes for richer soil diversity in temperate regions. Mark Dangerfield says that geological history plays its part as well.

"What really determines biodiversity is the the amount of disturbance you get to a system. In, in temperate systems what has happened is that you get major disturbances, they're called ice ages, and sometimes the soil is scoured or it's just completely removed, and then the soil has to be uh, recreated again."

And that makes room for more species to evolve beneath the newly formed soil layer.

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