The key to healthy ecosystems in the everyday world may lie beneath your feet.
A Colorado State University project, undertaken in collaboration with scientists in the United Kingdom, will attempt to catalogue and analyze below-ground organisms, see how they interact and determine how this affects the health of both soil and surface ecosystems, answering the questions of how human activities above-ground influence biodiversity below ground and what the consequences are of that change in biodiversity?
"I think the most exciting thing for us is to find out how life in soil is important in ecosystems," said Diana Wall, head of the U.S. effort and director of Colorado State’s Natural Resource Ecology Laboratory. "For example, we know more about earthworms because they’re relatively big and visible. But we don’t know if some are more important than others below ground. If we could find that out, it would be dynamite."
Scientific enthusiasm aside, there’s also a practical reason for carrying out the experiments, which are funded by a $1.8 million grant from the National Science Foundation.
"In order to maintain the planet sustainably, we need to know whether individual species in soils are critical to important things such as soil fertility, water quality, soil erosion, maintaining plant diversity and cleaning the atmosphere," Wall said. "How can we have a sustainable planet when billions of soil species and their importance remain unknown?
"Our project takes grasslands that are known to have great soil diversity and tries to discover the importance of these unknown species to our lives and our future."
The project will have applications to soil fertility, soil erosion, the cleanup and eventual reclamation of Superfund sites and to other contaminated areas that contain, for example, mine tailings.
"If we pollute the soil, can we expect continued aboveground diversity?" Wall said. "The answer obviously is ‘no,’ but we need to understand the resilience of ecosystems and whether soil biodiversity buffers the effects of soil pollution."
Wall, associate dean for research in the Warner College of Natural Resources, noted that the two million or so species already classified comprise an estimated 4 percent to 10 percent of all living organisms. They are the "easy ones," she said.
"We’ve looked at what birds do in an ecosystem, or what an elk vs. a moose does, but it’s much harder to look at soil microbes. They’re all microscopic."
U.S. researchers will conduct experiments at the Konza Prairie Long-Term Ecological Research site, or LTER, in Kansas and the Cedar Creek Natural History Area, a LTER site near Minneapolis. Both are tallgrass prairie remnants. United Kingdom scientists will carry out their investigations at the Sourhope grassland in southern Scotland.
The researchers face three problems. The first is accurate classification and identification of the species in soil. Classification, or taxonomy, has been "out of favor until we began to realize just how much biodiversity was being lost," Wall said. "In the 1980s we began losing birds and plants and realized that the same thing was happening to organisms in the soil."
A second factor is what Wall called "a deep, wide disciplinary schism" that has traditionally separated the scientists who classify organisms (taxonomists) from those who study ecosystems. The advent in recent decades of molecular biology has given science new ways to relate species, further weakening traditional taxonomy. The disappearance of species, however, has brought the need for taxonomists’ skills to the forefront once again.
A third difficulty is how to establish cause-and-effect relationships; for example, the role of a particular microscopic roundworm, or nematode, in the process of organic decomposition that puts carbon and nitrogen back in the soil.
"Knowing that we couldn’t look at everything, we decided what we could do most effectively" in experiments, Wall said. This was to look at soil biodiversity to determine what organisms are involved in the process of decay of organic matter. Researchers will examine how – and if – different levels of diversity affect, say, the speed with which a log decays. A second approach will involve changing what plants grow above ground and then determining what changes take place in life forms living beneath the soil’s surface – in other words, finding out if diversity above ground encourages diversity beneath. Wall suspects it does.
Scientists in the British Isles are working under a five-year, $8 million effort sponsored by the United Kingdom Natural Environment Research Council, roughly equivalent to the U.S. National Science Foundation.
Wall will work with Colorado State’s Andy Parsons, project manager, and William Hunt, a Natural Resource Ecology Laboratory scientist and professor of rangeland ecosystem science, as well as scientists from the Canadian government and other U.S. universities.
Grasslands in Kansas, Minnesota and Scotland (Australian and Dutch scientists are also interested) have somewhat different plants above ground, said Wall. The question is what’s in the soil.
"We know we’ve got the same functional groups," said Wall, listing bacteria, microorganisms, fungi, microalgae, protozoa, nematodes and invertebrates in ascending order of size. "What we don’t know is if we’ve got the same species or genera underground. So whatever we find out is going to be new and useful."