“Elephants and Tigers” Beneath Our Feet: Q&A with Soil Scientist Diana Wall

An Expert Opinion: Dr. Diana Wall

              “The Nation that destroys its soil destroys itself.”
                   Franklin D. Roosevelt, February 26, 1937

Civilizations and their economies can rise and fall based on the availability of fertile, healthy soils. Dr. Diana Wall, the winner of the 2013 Tyler Prize for Environmental Achievement, has been instrumental in shaping our understanding of the hidden ecosystems that lie beneath our feet. We talked with Dr. Wall about her work and why soil health and human health are so fundamentally intertwined.

"Dirt" or "soil" -- which term do you use?
I like soil. Dirt gives the idea that there is nothing beautiful in soil, that it is “dirty” and “dead,” yet the many organisms in soil can be extraordinarily beautiful if you put them under a microscope.

Your work in Antarctica and elsewhere has revealed we never really understood soil at all. How has our understanding changed?
Work in the Antarctic Dry Valleys, an extreme cold desert, has shown that tiny, microscopic invertebrates can be the top animals in the food web of this type of ecosystem. They are the “elephants and tigers” of the Dry Valleys even though they are hidden in soil. One species, a nematode roundworm [called] Scottnema, occupies the majority of the landscape and contributes about 7 percent to the valley soil carbon turnover, a needed contribution to regulating global carbon cycling. Soils in different locations have very different “communities” of organisms. It’s just like the life above ground -- a desert has very different species compared to a tropical forest. We have just begun to scratch the surface and explore soils to discover the exciting food webs under our feet.

Is biodiversity underground really as important as biodiversity above ground?
Absolutely! We wouldn’t see the diversity above ground if we didn’t have the diversity below ground. The species above ground, from the birds to the plant species, depend on specific communities of small organisms in the soil.

The organisms in the food webs below ground work for us cleansing our water, decaying leaves and trees, and returning nutrients to make soils fertile; detoxifying chemicals; stabilizing soils and preventing erosion; and as biocontrol agents, controlling diseases that affect animals, plants, and humans.

How will climate change impact life underground?
Climate change can have a huge impact on life underground. What’s surprising for many is that life underground can also have a huge impact on climate change. It’s a cycle.
Climate change can alter soil moisture through droughts or excessive rainfall or soil temperatures, which affects the soil habitat, the food that the organisms eat, and the physiology of the organisms. What we’re trying to do now is to learn more about where and when these changes in soil biodiversity will affect [our ability to] sustain our food, soils, air, and life above ground.

What's your favorite soil mini-beast and why?
Ahh… without a doubt it is Scottnema, the small, tough, resilient nematode roundworm from the driest desert on the earth, the McMurdo Dry Valleys in Antarctica. It is hard to believe it survives in such a hostile environment, but it survives by changing its physiology from worm-like to a tiny “Cheerio” -- and then blows across the landscape with the cold winter winds. Despite this, this tough animal seems very sensitive to changes in temperature and to increasing soil moisture, which is a concern with increasing warming in Antarctica.

How can soil scientists help advance our land management practices?
Let’s face it -- soils are under threat. We need lots of fertile soils to sustain our populations for the future. Soil scientists have the training to appreciate the different soil habitats and the individual contributions that soil organisms make to fertile and stable soils. All scientists can help to integrate and transfer this new knowledge about soil biodiversity for improved soil health, for the health of us all.

If everyone reading this interview committed to one thing to protect soil life, what should that one thing be?
They can help us protect and conserve and restore our living, teeming soils just as we protect clean air and clean water. Soils are being degraded at a rapid rate. We can all work to address the causes: contamination and pollution, erosion, sealing of soils by concrete, climate change, invasive plant and animal species, and the decline of organic matter.

Follow Dr. Wall’s current Antarctic research endeavors at her blog,The World of Nematodes.