Do you know
Don't you wonder
What's going on
(David Crosby, "Déjà vu")
MCDOWELL CREEK, Kan. - As I write this, a rainy spring is expressing itself on the prairie in lush grasses and effusive flowers. But down under the ground, in darkness and invisibility, there is an even larger world, even more vibrant and various. This is the "belowground habitat," and it is the focus of increasing study. Ecologists now think the belowground habitat holds many of the secrets of the prairie's power.
Biologists call native prairie an "upside-down rain forest," because the majority of its biomass is underground. The grasses may appear "tall," but their aboveground foliage is nothing compared to the tangled mass of roots below. Just one square yard of prairie soil can contain 150 miles of roots! Similarly, the greatest biodiversity on the prairie is also underground. One teaspoon of prairie soil can house as many as 5 billion creatures, from an array of species, many of which have yet to be identified. There are throngs of fungi, bacteria, protozoans--and hordes of tardigrades, nematodes, springtails, pseudo-scorpions, earthworms, and mites.
Indeed, John Blair, principal investigator of the Konza Prairie's Long-term Ecological Research studies, calls native prairie's belowground habitat "one of the last frontiers in biodiversity studies." In fact, some ecologists are already calling this locale the most diverse environment in the world.
Despite the unknowns, it is clear that the belowground habitat provides vital biological services. A prairie is better at cleaning the air than is a forest, mainly because its subterranean creatures are good at taking carbon dioxide out of the air and storing it in stable carbon compounds in the soil. The belowground habitat also helps the grass to grow. There are special fungi associated with the roots of forage grasses, and without those fungi, the grasses suffer from phosphorous deficiency and dwindle away. Similarly, bacteria associated with certain wildflowers convert atmospheric nitrogen--which plants cannot use--into plant-available minerals.
The belowground creatures are also involved in nutrient recycling. They break down dead plant matter, release nutrients from humus, and store nutrients in their own bodies. Living, they are like little capsules of fertilizer, and dying, they are those capsules on timed-release. All together, they create a buffer against extremes of weather. Through processes still not fully understood, they hold onto nutrients in times of flood and moisture in times of drought.
When a cow or a bison takes a mouthful of grass, the grass responds by shedding carbohydrates from its roots. This is like calling in the cavalry, for billions of soil creatures rush to the spot to slurp up the sugary soup. In return, these creatures provide the nutrients the grass needs for a spurt of regrowth. Then when the big grazers return, they will find a second meal. That's how cattle and bison can eat their cake, and have it, too.
Dr. Blair was attracted to belowground research, he says, because he was "struck by the importance of little things." I too find this paradox compelling. In an ecosystem of vast expanses and massive grazers, the power of tiny beings is striking. It resonates with other aspects of our world which we also do not fully understand-- other ways in which the mighty depend on the meek, and the last become first.