Discovery: Good ol' tallgrass was formed by good ol' bacteria
It's always tempting to reflect on how wonderful the West used to be. You know what I mean: Conservationists and Natives lament that the first invasions by white settlers wrecked everything, and ranchers and loggers long for a return to the era before 750-page environmental-impact statements. Who among us hasn't conjured up wistful images of the good ol' days when the prairies played a symphony of native plants and wild bison herds plodding to the horizon, and the mountains sang out hymns of old-growth forest sanctums, hormone-disruptor-free streams, untrapped beaver and unshrunk glaciers?
One of my favorite images, evoked in histories of many Western places, portrays the original grasses in a wonderful way: The good ol' grass grew so tall, it brushed the stirrups of cross-country horse-riders. "Early American surveyors riding through the virgin tallgrass prairie found the grass stirrup high to their horses," says a typical account, from a federal Environmental Protection Agency report. Another, from The Elemental Prairie: Sixty Tallgrass Plants, describes a pioneer-era horse ride by Army officer and Western explorer Stephen Kearny: "It was virgin tallgrass prairie, and Kearny and his men rode stirrup-deep through young bluestem and flowers ..."
There are many accounts of stirrup-high native grass on the good ol' prairies, as well as in the good ol' mountain valleys, and even the good ol' Southwestern deserts. William O. Douglas, the only unabashed conservationist to serve on the U.S. Supreme Court, got sentimental about stirrup-high grass in the good ol' Pacific Northwest. The image also appears in the definitive biography of President Lyndon Baines Johnson, in a description of the first white settlers in the good ol' "Hill Country" around Austin, Texas: "... when they saw the grass, they felt the journey had been worth it. 'Grass knee high!' one wrote home. 'Grass as high as my stirrups!' wrote another. The tall grass of the Hill Country stretched as far as the eye could see, covering valleys and hillsides ..." There's even a "cowboy prayer" describing the tallgrass as a heavenly experience we can enjoy once again after we die, "when we make that final ride to the country up there, where the grass grows lush and green and stirrup high ..."
Modern researchers occasionally conclude that a particular account of good ol' stirrup-high grass is a myth, but by and large, the remembrances are considered legitimate. The remembrances are also melancholy, as the native tallgrass that once covered more than 100 million acres in this country has been almost completely wiped out by sodbusting for farming and other developments, as is shown by this Nature Conservancy map of some of the remnants of untilled prairie (the dark green areas hadn't been tilled by 2003, yellow areas had been sodbusted):
I'm writing about this now, not only as a sentimental remembrance, but also to point out a new scientific discovery. A team of researchers led by the University of Colorado-Boulder has found that the good ol' tallgrass apparently owed its existence to something very subtle -- "the diverse assortment of microbes that thrived in the dark, rich soils beneath the grass," especially "a poorly understood phylum of bacteria, Verrucomicrobia."
This is cutting-edge science that could be helpful in efforts to restore tallgrass and other native plants. The researchers used DNA sequencing to identify the bacteria in soil samples from 31 remnants of native prairies, mostly in nature preserves and cemeteries, and published their findings in Science magazine's November issue. Microbial ecologist Noah Fierer, lead author of the study, says, "These soils played a huge role in American history because they were so fertile and so incredibly productive. They don’t exist anymore except in really small parcels. This is our first glimpse into what might have existed across the whole range. ... It was very hard to find sites that we knew had never been tilled. As soon as you till a soil, it’s totally different. Most gardeners are familiar with that."
The good ol' Verrucomicrobia bacteria were important for carbon cycling in the soil, the researchers believe, and "seem to thrive in soil with poor nutrients, which might explain why they are less common on land that has been farmed and fertilized," says a Nature magazine report about the discovery. It "suggests that one of the most dramatic aspects of that landscape transformation was the loss of microbial diversity in prairie soils. ... With (genetic) sequencing becoming cheaper and easier -- a study on this scale would not have been feasible even five years ago -- scientists are just beginning to characterize the diversity of soil microbes in prairies and elsewhere."
Scientists now hope to grow this particular bacteria in labs -- a difficult process -- and use it, along with transplants from remnants of native soil, to spur restoration efforts. "To fix a damaged ecosystem you need to start from the ground up -- with the microbes that live in the soil," says a New Scientist report on the discovery. "The first step in that direction has been taken for the tallgrass prairies of the US Midwest -- a once fertile landscape now described as a near-extinct biome. ... Ecologists who restore endangered ecosystems traditionally focus on bringing back native animals and plants, but a growing body of evidence is revealing the crucial roles that soil microbes play in ecosystem stability. They break down organic matter, recycle nutrients, and can influence plant health and productivity. However (most) microorganisms have largely been ignored in ecosystem restoration projects."
"Now that we have a best guess of what native bacterial communities looked like, maybe we can start asking whether there are specific bugs we can use to accelerate restoration," Fierer told New Scientist. "It opens a whole research area," Charles Rice, a soil microbiologist at Kansas State University, told Nature.
Beyond Pesticides, a nonprofit advocating for the reform of chemical-intensive, sodbusting farming, says this discovery "builds upon a mounting body of evidence demonstrating that conventional farming methods not only destroy habitat, they also destroy soil structure and affect plant health and crop production. ... The study opens up a range of further research possibilities for soil science, demonstrates the importance of soil microbial communities and provides guidance on sustainable soil management."
Even The New York Times editors have spotlighted this discovery with a touch of sentimental melancholy about the good ol' tallgrass: "Even if you have stood on a remnant of virgin prairie, it is hard to imagine what was lost when the tallgrass prairie was plowed," says a Times editorial. "Settlers were staggered by the scope of the prairies, and they were more amazed by the richness of the soil. The biomass of roots beneath the ground was as dense and tangled as the biomass on top. And when the prairies were plowed, everything changed -- the ecosystem, the structure of the soil, and, as it turns out, the microorganisms living in the soil. ... Finding these bacteria is like finding a piece of a lost continent. ... No one who rode across the prairie in the 19th century through grasses up to their stirrups ever stopped to admire the subsoil bacteria. Yet they were as distinctive as the bison grazing in great herds above."
This is also another indication of complexity of wild ecosystems, and how little we understand about them -- a message framed in detail in a recent High Country News magazine cover story.
HCN has also spotlighted the destructive effects of sodbusting prairie over the years, with wonderful prairie wildflowers., a and . Also I blogged recently about a Montana photographer's images of
Reference list for those who might like to tour or research remnants of native grassland:
North and South Dakota
Ray Ring is a senior editor of High Country News. First (cropped) photo of grasses from Flickr user Seth Beres/USFWS Mountain-Prairie region, second photo of grasses from Flickr user QtrFlash.