What is Grade A prairie?

Very high quality or "Grade A" prairie is rare, beautiful, and a major inspirer of biodiversity conservation. Once you've come it know it, the rich complexity of shapes, colors, and animal-plant interactions takes your breath away. But in degraded form, it does not look like much.  

In the photo below (from about 1980) Prof. Robert Betz shows me a part of the great Gensburg-Markham Prairie, before restoration in this area had begun. 

This is a prairie? Yes, it is. And the entire site –  one of the finest prairies in the state – was also this badly degraded by brush when Betz started restoring it. 

Q: What makes this tangle, ecologically, a prairie?  

A: All those woody plants are short-term invaders; their shade has not yet killed off most of the ancient biota here, which is comprised of hundreds of species of prairie grasses and wildflowers, as well as thousands of species of animals (bees, snakes, voles, beetles, fungi, symbiotic bacteria, and all) that represent a rare heritage of biodiversity. 

Many people, including some scientists, told Betz that, if he cared about nature, it would be wrong to cut all those trees. When he started there in 1972, few people understood what either prairies or nature were. He patiently educated us.

 

As Betz and colleagues cleared the brush, rich prairie bloomed again, at first a few acres, then scores, then hundreds. This photo shows restored, original Gensburg-Markham Prairie in July.

 

Betz was a pioneer of prairie conservation. He searched for and studied prairie remnants, finding them mostly on old, fenced-off railroad rights-of-way and settler cemeteries; as he did, he began to notice that the rarest plants were highly-unevenly distributed. Some remnants had none at all. In some, great numbers of the rarest prairie plants were sprawled all over each other. 

In the process, he began to clarify the meaning of the word nature. Later, in Earth's first serious search for true surviving remnants of nature, the Illinois Natural Areas Inventory, building on Betz's work, settled on the following categories:

Grade D - severely disturbed

Grade C - somewhat disturbed - good quality  

Grade B - high quality (rare - 220 acres of mesic prairie survived in "The Prairie State" at that time)

Grade A - very high quality (rarer - 54 acres survived in "The Prairie State" at that time)

Those all-important Grade A and B prairies represented 1/100th of 1% of the original. 

For more on how they were identified and defined, read on (and check out Endnote 1).

The next two photos show somewhat clearly something that's usually hard to see. They show the same spot in Somme Prairie from either side of the dividing line between “Grade A” and “Grade B” prairie. 

 

In the first photo, looking east, the Grade B ("high quality") prairie is in the foreground. You can easily see, just a few feet back, where the Grade A ("very high quality") starts, abruptly. A fence once stood there, long ago, when farms stretched to the horizon in all directions. Horses or cows had grazed the now-Grade B side of the fence, enough to reduce its quality somewhat. But it still has some relatively conservative species including hoary puccoon, violet wood sorrel, yellow stargrass, prairie violet, alumroot, two-flowered Cynthia, and many more. Thus, it was identified as Grade B prairie. 

 

In the next photo, I’ve walked across the old fence line into the Grade A prairie, turned around, now facing west, and photographed the same area, from the opposite direction. Now Grade A is in the foreground, and the Grade B in the rear. The plants that stand out visually in the foreground are prairie dock, gayfeather, and rattlesnake master. But the real treasure of the Grade A is the list of highly conservative species that survived here but not in the Grade B. They included prairie gentian, cream false indigo, leadplant, prairie coreopsis, prairie lily, Kalm's brome, edible valerian, Junegrass, prairie Indian plantain, oval milkweed, alumroot, and many many more. 

The old fence, once along a property line between farms, is long gone. But the impacts of the grazing on the other side of that fence line were still dramatically apparent when this photo was taken, in the 1980s. (Today, after decades of restoration, the contrast is not so dramatic.) 

 

Decades ago, the Forest Preserve District acquired the parcel with the Grade A prairie. They planted trees on it (as you can see, in the first of the two photos above), but some of the precious prairie survived. 

In the photo below, the land on the west side of the fence was acquired by the U.S. military in Cold War 1960, and they built a radar installation to protect us from Soviet missiles. 

Here, looking north, Dundee Road is just below the bottom of the photo. North of the radar installation is Underwriters Labs. The military mowed its property occasionally. Occasional mowing does not rapidly damage the plant community. When the radar was no longer needed, this land went to the Forest Preserve District and is now part of Somme Prairie Nature Preserve. 

In the photo above, the Grade A prairie remnants (only two acres in total) are on the Forest Preserve land along the right (east) side of the photo. But when this rare prairie land became a Forest Preserve in the 1940s, the staff planted trees. Additional bird-dispersed and wind-dispersed) trees arrived as well, slowly degrading what was left of the prairie. Like in Markham, when restoration began, the Grade A area of Somme in the 1970s looked like an open woods, if you didn't know what all those rare grasses and wildflowers indicated. Grade A prairie is so dense with highly-competitive species that it can resist invasion by trees for decades. Thus some bits and pieces hung on, to be saved and restored. 

For a bonus photo of the Grade A area of Somme Prairie in the 1980s, recovering after a few restorative burns, see below:

Blooming in this May photo are cream false indigo, hoary puccoon (orange), downy phlox (pink), golden Alexanders (yellow), and shooting star (pale pink). Over the summer, scores of other wildflowers and grasses will rise over these short spring species and bloom in turn, many accompanied with their associated, specialized pollinators, herbivores, and predators, from insects and spiders to prairie birds and coyotes. It's rich.  
 

For another perspective on these questions, check out this adventure story that comes with plant lists, scientific names, and discussions of the rare species that indicate prairie quality.

For photos of Somme Prairie today and some restoration details, click here.  

How much difference does prairie quality make?

No one can answer this question with certainty. But much of the genetic richness created by millions of years of evolution (species and genetic alleles of great potential significance to our unique Planet of Life) may reside mostly or only in high-quality remnants. We who work to save them do so at some level because we love nature and think it ethically unconscionable for our hubristic species to utterly wipe out the last of what took millions of years to evolve. But there are practical reasons too. 

We know for sure that from time to time a major food crop is threatened by some disease which, like the Irish potato famine, could result in the starvation of millions. We know for sure that agronomists go to nature to find genes in wild relatives that can rescue such crops. We also know that biodiversity is a major sources of genes for improved nutrition, medicines, industrial solvents, lubricants, catalysts, etc. When they're gone, our planet and posterity are diminished. 

But also, consider this thought experiment: There have been times on Earth when most species have rapidly gone extinct because a key balance was lost. For example, the oceans turned toxic and stopped producing oxygen. Or ice or drought covered most of the planet. We now recklessly tempt fate with planetary manipulations. Imagine a time when a global ecological catastrophe is developing and scientists discover that a solution would be to restore a billion acres of temperate grassland. But it would only work if certain bacteria or algae or nematodes were part of the mix. If those species only survived in Grade A Nature Preserves, we'd use them to rescue the planet. If they survived nowhere, we would have lost that option.

I'm aware that the "what ifs" above are speculative bordering on the ridiculous. Yet there are a thousand other scenarios that might depend on saving at least some nature. We're barely starting to understand what makes Earth work for life as we know it. Considering all the resources and power that our species now has, biodiversity conservation requires only a miniscule investment. We should do it. And be happy about it. 

Endnote 1

Normally you can't easily see the line separating A and B prairie. To tell the difference, you have to identify the species.  Below is the list of the nine species most indicative of Grade A mesic black-soil prairie. Their coefficients of conservatism ("CC") rate “perfect tens.” (See Swink and Wilhelm or Wilhelm and Rericha).   

Common Name	CC	Scientific name Wilhelm and Rericha	Scientific name Swink and Wilhelm
cream wild indigo	10	Baptisia leucophaea	Baptisia leucophaea
scarlet painted-cup	10	Castilleja coccinea	Castilleja coccinea
white prairie clover	10	Dalea candida	Petalostemum candidum
prairie gentian	10	Gentiana puberulenta	Gentiana puberulenta
prairie white-fringed orchid	10	Platanthera leucophaea	Habenaria leucophaea
prairie lily	10	Lilium philadelphicum	Lilium philadelphicum
prairie panic grass	10	Dichanthelium leibergii	Panicum leibergii
prairie dropseed	10	Sporobolus heterolepis	Sporobolus heterolepis
heart-leaved Alexanders	10	Zizia aptera	Zizia aptera

In a Grade A prairie, most of the above species will be plentiful, along with many others that have CCs of 9 and 8. 

In Grade B prairie, there may be some of the above species surviving, but only here and there in most cases, and with many of them missing entirely.

In Grade C prairie, species in the 8, 9,and 10 range will be few and far between, if any occur. 

The list of the nine species was a simple way to make the point. But for prairie quality assessment, the following longer list may be more helpful. These 26 characteristic mesic black-soil prairie species have conservatism coefficients 8, 9, or 10. 

Scientific Name	CC	Common Name
Amorpha canescens	9	Lead plant
Asclepias sullivantii	8	Prairie milkweed
Aster azureus	8	Sky-blue aster
Aster laevis	9	Smooth blue aster
Baptisia leucophaea	10	Cream wild indigo
Bromus kalmii	10	Prairie brome
Carex bicknellii	10	Prairie oval sedge
Carex meadii	9	Mead’s stiff sedge
Castilleja coccinea	10	Indian paintbrush
Eryngium yuccifolium	9	Rattlesnake master
Gentiana puberulenta	10	Prairie gentian
Platanthera leucophaea	10	Prairie white-fringed orchid
Heuchera richardsonii	8	Prairie alum root
Hypoxis hirsuta	9	Yellow star grass
Lilium philadelphicum	10	Prairie lily
Lithospermum canescens	8	Hoary puccoon
Oxalis violacea	9	Violet wood sorrel
Panicum leibergii	10	Prairie panic grass
Pedicularis canadensis	9	Prairie betony
Petalostemum candidum	9	White prairie clover
Petalostemum purpureum	9	Purple prairie clover
Potentilla arguta	9	Prairie cinquefoil
Phlox glaberrima	8	Smooth phlox
Sporobolus heterolepis	10	Prairie dropseed
Viola pedatifida	9	Prairie violet
Zizia aptera	10	Heart-leaved Alexanders

For additional details and discussion, see that "adventure story, which comes with plant lists". 

For conservation purposes, the working hypothesis is that Grade A prairie will also have the best surviving associations of the (poorly known) species of bacteria, fungi, protists, pollinators, etc. that are interdependent with the various species of prairie plants and animals. However, work by Ron Panzer has shown that some rare insect species may survive better on larger, somewhat-degraded sites than on the much smaller Grade A sites, which may be too small to sustain their populations. 

References

Floyd Swink and Gerould Wilhelm, Plants of the Chicago Region, 4th edition, 1994

Gerould Wilhelm and Laura Rericha, Flora of the Chicago Region, 2017 

Acknowledgements

Much of the early knowledge of prairie quality (and remnant restoration techniques) came from the wise and visionary Dr. Robert F. Betz. 

The restored Markham photo is by Michael Jeffords and Susan Post. 

I don't know where the radar installation photo came from, possibly Northbrook Historical society? I just had it in my files. 

Thanks to Christos Economou and Eriko Kojima for many helpful edits.