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Tuesday, January 17, 2017

Bison Hypotheses

I was chided, rebuked, and otherwise treated to emotions by responses to two bison posts. I had celebrated the arrival of bison at Nachusa Grasslands – one of the great suspense-filled dramas and triumphs of contemporary conservation.  

Very quickly there emerged pro and con.

Many people quickly expressed a zeal for finding creative ways to get bison to their favorite Illinois prairies – as if a quality grassland couldn’t properly thrive without grazing. Opponents expressed passionate concern that “big stompy beasts” would destroy our last, precious prairie remnants.
Bison now graze parts of Nachusa Grasslands. Will they wreck it - or make it whole?
So, to tackle the first question first:  

Do we need big grazers to have “real” and thriving prairies?

In my first bison post, I tried to convey the special and radical nature of the Nachusa experiment. Here’s a rehash of that footnote, upgraded now to main text:

Some people have criticized the restoration of plains bison (known scientifically as Bison bison) as “unnatural.” It is true that the eastern tallgrass prairie seems to have had Bison bison grazing it in large numbers only for only a couple of hundred years. Archeologists had wondered why they found few bison bones at Illinois Native American sites. Odder still, at the very oldest sites (10K+ years ago) they found many bones of two other species of extinct bison (Bison latifrons and Bison occidentalis) along with mammoth and mastodon bones.

As evidence mounted, a consensus developed that the eastern tallgrass prairie was so productive a habitat that the original Native American populations rapidly became too great for the coexistence with megafauna. Mammoths and Bison latifrons had evolved in prairies for millions of years – before the arrival of the crafty omnivorous humans. New to the continent at that time, human beings with the (stone) technology to hunt large mammals rapidly killed off the tallgrass megafauna. One smaller species of bison, the plains bison, survived in the sparsely inhabited western plains. Those bison that European explorers saw in Illinois had come east only after 1492 when European diseases began to reduce Native American populations drastically, some say by 90%.

Then after a couple hundred years of plains bison on the Illinois prairie, in the 1800s, the crafty omnivorous Euro-Americans drove Bison bison back to the plains once again. But almost all the plants and animals of the tallgrass prairie are much older than a few thousand years. They didn’t live here when this land was under glacial ice, but they perpetuated their kind on prairies that retreated south. Bison and a large proportion of other tallgrass plant and animal species evolved through the 2.6M years of the Pleistocene. One study suggested that most grassland bird species today are a few hundred thousand years old – evolving from earlier forms. 

Lurking in this history, as I perceive it, are two contrasting perspectives - both of which seem true to me. First, Illinois prairie remnants do not need bison to survive and thrive as healthily as they had for ten thousand years.  Second, bison are of great value at Nachusa if we hope to replicate how the  prairie species interacted for most of their millions of years of evolution. A consideration of these two contrasting but compatible perspectives also leads to questions about “the meaning of nature” – which we’ll get to a few paragraphs down (if your attention lasts that long).

For the last few thousand years our prairies may have evolved and flourished here with few large grazers. But evolutionarily, ten thousand years is a short time. Before the coming of people, the ancestors of prairie plants and animals flourished over much of North America, including what is now Illinois, with many large grazers playing a key role, as have world’s grasslands generally, for millions of years.  

Range Wars on Missouri Tallgrass

A lot of the “bison negative” comments originated from a long-running conflict in Missouri. Prairies on state conservation land there were said to be damaged by poorly managed cattle and bison. I tried to check out those reports.

Apparently the only "data" available were photographs. That seemed odd to me, since the critics were scientists, who you’d expect would have scientific sampling data. A photo, taken of a high-quality prairie in 1995, showed many coneflowers and coreopsis in bloom. A second photo, said to have been taken after over-grazing by cattle, at the same place and time of year in 2010, showed few flowers.

I had asked one knowledgeable scientist about those photos and was told that some people had panicked about some temporary impacts – but that after a few years the apparently overgrazed prairies were as healthy and diverse as ever. Perhaps I gave too much credence to that opinion?

Thus, I was disappointed to see the Nachusa experiment attacked on the basis of apparent misinformation. Yes, an experiment as bold as Nachusa's should welcome challenges and debate. But I kept hearing reference to out-and-out, proven calamities in Missouri. Was it needless panic or sure proof? Who was right?
In Nachusa's former corn fields, such quality plants as pale purple coneflower and white prairie clover
 now bloom by the thousands over hundreds of acres. Too many cows damage such vegetation.
At Nachusa, bison seem to avoid it, so far. 
Ecosystem conservation is still in its “battlefield medicine” stage. As conscientiously as we pursue scientific decision-making, many questions are necessarily answered on the basis of “best available information and judgment.” Experts disagree, even on some of the fundamentals. Thus we experiment with and compare varying approaches, using the best data we can get.

There had long been conflict among Missouri conservationists about grazing prairies. Some good people argued that, if we are to retain large enough grasslands for rare prairie animal populations, our continent needs to retain the vast prairie acreages that survive only on private lands, owned by ranchers for grazing cattle. Conservation agencies and the government don’t have remotely enough land, so we conservationists need to be cooperative and friendly with the grazing industry.

No one disagreed with that goal, but biodiversity conservationists sometimes criticized some conservation agencies for taking “cooperation and friendliness” too far. It turns out that the Missouri Department of Conservation had decided to experimentally replicate bison grazing on high quality Niawathe Prairie with experimental patch-burn grazing by cattle.

Many government and private agencies have been developing techniques and expertise on patch-burn grazing (PBG). Some experiments showed PBG to be good for prairie birds and good for getting the most beef per acre. Some people had extrapolated those results to “PBG is best for cows, best for the soil, and best for biodiversity.” But there seems to be little data on that biodiversity question for high quality prairies in the eastern tallgrass region. Perhaps it will turn out that PBG is best for some rare species and not for others. The fundamental idea of biodiversity conservation is to save all the species, alleles, and ecosystem types, and it’s likely that a variety of approaches will work better than “one size fits all.”

 (The patch-burn grazing hypothesis is that over time the animals and plants will thrive, as grazed and un-grazed patches move around the landscape, because this was how this community evolved for millions of years.)

In response to the controversy, Doug Ladd, science director of the Missouri Nature Conservancy, wrote an eight page report discussing when and where grazing was compatible with biodiversity conservation. One of his summary statements was,
“Grazing … in … high quality prairies should be accompanied by disciplined, repeatable, dispassionate monitoring protocols … that document … the degree to which the most sensitive, least replaceable elements of the system are being sustained. These data should be available to provide adaptive management feedback on an ongoing basis.” 

Missouri DOC vs. Nachusa TNC

As I researched, I came across an impressive YouTube presentation by influential Missouri biologist Paul Nelson. He was alarmed by what he had seen cows do at Niawathe (and expressed concern about what bison might be doing at Regal Prairie). High-quality prairie species were being replaced by weedy, grazing-resistant ones, he said. He had once supported the concept of experimental grazing by cattle and bison, but he now believed that a worthwhile experiment had run amok.

In the YouTube video, Nelson was addressing a Missouri Academy of Sciences audience, including many prairie conservation advocates. He spoke to the politics of the situation. “What makes prairie management a challenge is that different managers and the public at large have different reasons or needs for management,” he said. Hunters, birdwatchers, cattle ranchers, and biodiversity conservationists all have desires to be satisfied on Missouri’s public lands. “There is diverse ownership with all these conflicting values.” 

Then he described a drama. After biologist Don Kurz disseminated a 45-page report critical of grazing by cows at Niawathe, conservationists raised their voices and got results. As Nelson put it:

“I am really proud and pleased to know that very quickly so many environmental interest groups and individuals rose up because of their concerns ... People are still sensitive to what we do and don’t do to manage some of the best high quality natural areas in the state.

Those who wrote letters included the Joplin Environmental Task Force, an Audubon society, a Nature Study Society, Missouri Native Plant Society, and, especially influential, an agency that had been one of the most ardent supporters of grazing, the Missouri Prairie Foundation.

When the Missouri Department of Conservation put PBG cows on Niawathe and bison on Regal Prairie, they did it as an experiment. They committed to take data and analyze the results. These may have been among the first times that patch-burn-grazing was employed on a high-quality tallgrass prairie. It was an important experiment. Surely by 2017 there would be well-analyzed data available to the scientific community and the interested public. Yet I could not find a published reference. I wrote to the agencies concerned and got no reply.

Nelson warned that on public lands, administrations change, and those new administrations might be dangerous to the ecosystem. He told his audience, “You have to have advocates – of scientists and organizations like you – to make sure that during those times of organizational change that managers are held accountable.”

Nelson’s 2010 talk assured the audience that an expert team was putting together an improved research plan. But now it’s seven years later. Is there no urgency to make better decisions on the basis of data and analysis?
How does the Missouri experience compare with Nachusa? The apparently troubled Missouri grazing experiments have had to deal with influential interest groups, politicians, and politics. The Nachusa decisions are being made entirely by conservationists, on the basis of science. (Of course the prairies too are quite different - on the richer Illinois soils compared to the ancient, unglaciated soils of southern Missouri.)

At Nachusa, many years of detailed study preceded the first nibble by the first bison. The accumulated data covers:
  • Plant communities: 22 fenced-off grazing exclosures with transects inside and outside each fence – plus over 100 additional permanent transects
  • Data on endangered plant populations including the prairie bushclover and prairie white-fringed orchid
  • Breeding bird transects and “point counts”
  • A number of long-term studies of invertebrate animals
  • Telemetry tracking of ornate box turtles and Blandings turtles
  • Snake monitoring transects

Nachusa manager Bill Kleiman is proud of the level of science under way at Nachusa, but he wants more. “We have about two dozen researchers out here, with science ramping up year after year.  Our Nachusa science budget is ten-fold what it was five years ago. But we still have more monitoring we would like to do.” It likely will take a couple more years at least before bison impacts, of whatever kinds, will show up in the data.

All the same, it would be great if Illinois could learn more from what happened in Missouri. It would be so helpful to see the best before-and-after data. How has the recovery gone, on the sites where the grazing has been reduced or eliminated? Were conservative plant or animal species lost or badly diminished? Were there other benefits or losses? What is being learned on the sites where the grazing continues?  
At Nachusa, some of the high, dry "grazed out" knobs have recovered to an impressive degree.
Will the buffalo herd reverse that recovery - or speed and improve it yet more?
Overall, the Nachusa experiment with bison is widely seen as ambitious and wise. But how about the small high-quality remnants within it? How are they being monitored, and how are decisions being made about them? Schafer Knob, perhaps the best quality remnant at Nachusa, had long been grazed down to the nubs, and what survived there should survive the worst the bison could do, at very least for a few years. Nachusa, of course, will not see the worst the bison could do. Good science and a large caring community of stewards will see to that. And then, most of Nachusa is not remnants; it is thousands of acres of former cornfields, sowed to prairie and now being grazed by bison. Indeed, that’s where these megafauna graze most.  
Twenty two exclusion fences will help Nachusa monitors study the impacts of bison - pro, con, and otherwise. 
What will these experiments teach us about nature? This is the era on planet Earth that people are calling the Anthropocene. We the people, by necessity, make the decisions on which nature depends. We decide so much, on so many levels:
  • “How often and under what conditions will nature burn?”
  • “In the absence of wolves, should conservationists cull deer?”
  • “Will we bother to go to the hard work of restoring mega-fauna (like bison)?”
  • “Should a given preserve have 50 bison? Or 250? Or how many?”
  • “Should endangered species get extra care, or allowed to go belly up?”

In fact, these discussions remind us that as we learn, we continually need to grapple with yet more abstract questions: “What is a natural area?” “What is nature?” “What are our goals as conservationists?” We need answers because we have to make decisions.
The Midwestern natural areas programs in the 1970s launched something new on the planet. We hypothesized that certain little patches of rare plants represented “original nature.” The hypothesis expanded to a prediction that these areas would thrive if not disturbed in the future. We quickly learned that caring for little nature preserves would require a lot more work than we thought.
Over time, many conservationists became concerned that we were too exclusively focused on areas rich with rare plants, but too small for conservation of most animal communities, with which the plants were ultimately interdependent. Yes, our originally conserved “natural areas” are precious and crucial. They deserve respect and care (indeed, better care than they’re getting, in many cases). But so also do our larger areas deserve respect and care, where the goal is to restore as much of nature’s full dynamics as possible.
Stewards control invasive weeds on Dot's Knob. There may never have been a large grassland
with as much stewardship help as Nachusa. But every steward agrees, it deserves more. 
One great source of learning will be the large, well-managed, grazed and ungrazed grasslands at Nachusa (and comparable large and small efforts in so many places). Fun! Stay tuned! Or join in!
Flannery, Tim. The Eternal Frontier. 2001. Grove Press. Includes a good summary of the deep history of North American grasslands and their grazers.

Ladd, Doug. “Patch Burn Grazing and Missouri Tallgrass Prairies – The Nature Conservancy’s Perspective.”  January 2011
Paul Nelson. YouTube Video of a speech to the Missouri Academy of Sciences.
“Patch Burn Grazing: Is It Right for Missouri’s Remaining High Quality Prairies?”

“Nachusa: Fun People and Ornery Bison”  
“What Would Bison Do?” 

Friday, September 16, 2016

Gray Goldenrod – How important might it be in the Greater Scheme Of Things?

My popular field guides list its habitat as “woods and open places” or “old pastures, dry open woods.” Many of us know it best from beat-up old fields. It’s largely absent from many older “restored” prairies. Yet it can be common in the finest remnants.

Swink and Wilhelm use the name “old-field goldenrod” and list only four habitats – old fields, dry prairies, dunes, and sandy black oak savannas. 

But its habitat at the recovering savanna at Somme Prairie Grove includes many of the very "best" spots. This September, I found myself puzzled by its distribution. Though gray goldenrod (Solidago nemoralis) was thriving in some fine areas, it had dropped out of some of the plots that we’ve thought of as recovering especially well. Are we missing something?
This short, cute goldenrod often has a jaunty little "elf cap" look at the top. Here it's growing
with Kalm's brome, purple prairie clover, wood betony, smooth blue aster, and much more.   

I first trekked to a "Middle Slope" patch where many of the most conservative prairie (and savanna) species were coming in well. These include prairie violet, prairie gentian, alumroot, and shooting star. It was an area where we hadn't actually done all that much - except for scores of burns and occasional light seeding. 
The cages protect prairie gentian from the deer. Sure enough, gray goldenrod was thriving here,
along with lead plant, rattlesnake master, and perhaps too much tall prairie grass. 

I worried about the denseness of the tall grasses that were coming in. We'd planted no big bluestem at all, but the little that was already on the site spread vigorously - especially where we hadn't yet been able to establish tough, conservative competition. When I studied the turf here, I was pleased to see a lot of the species that might regulate the abundance of otherwise over-exuberant grasses.
The matted leaves of pussytoes cover most of the ground. Leaves with long fingers are prairie violet.
Fern-like clumps are prairie betony. The longer leaves and stems are big bluestem and rattlesnake master. 

Perhaps the density of competition in this area will keep the taller grasses from becoming over-dominant - as they do in most restorations but never in fine remnants.
This nearby area seems to be ready and begging for more conservative seed. I worry,
will the Indiangrass become over-dominant if we don't provide the diverse competition?

And in another nearby area, I had opposite concerns. Here we had done a lot of seeding, and the existing diversity might be at risk.

Here young dropseed grass (clumps of fine leaves) will give the Indian grass a run for its money,
and there's great diversity of conservative legumes, asters, violets, and scores more.
But how secure is that diversity as the more mighty conservatives continue to drop seed and mature?

I stop by a third area, where we had long-ago found and favored the then-threatened small sundrops. Here, because the sundrops could likely not survive dense prairie competition, we'd been careful to seed only small amounts of some conservative species, slowly over the years. A success? Perhaps not for the sundrops; it is now much reduced (although moving to brushy edges, which perhaps is more its habitat). Yet this slower and more restrained seeding was highly successful for many conservatives including Seneca snakeroot, June grass, scarlet painted cup, prairie white-fringed orchid, and others. Yet, I still worried, as you may understand, looking at the dropseed in the two photos below. 
This area certainly looks good enough, but in spots with four or five clumps of dropseed together, there seemed to be little or nothing else growing in between them. Is the conservative diversity we see here temporary as the dropseed expands?

In the densest patches of dropseed, it seemed like the gray goldenrod (and much other diversity) was now pushed out.

I walked quickly to another experiment. Here, I looked and worried. Not only was the gray goldenrod missing, but the whole late summer and fall flora looked very weak. This area represents a complicated experiment that deserves its own write-up some time. But it was now our largest and densest stand of dropseed, prairie clover, and a few other fine species. People marveled over it in July and August. But look at it now. 

About an acre of dense dropseed and prairie clover looked colorful and diverse a month ago.
Does the lack of flowers now suggest something is wrong? 

Close up of same area. We expect a high quality grassland, whether prairie or savanna, to flower richly all season long.
Though we've seeded the late-season species here as much or more than in the sparser areas
(where the gray goldenrods still thrive), the colors of diverse ecosystem health seem not to be here now. 

Is this experiment telling us something? Did we seed too heavy and fast here 35 years ago? Is the lack of gray goldenrod a mine-canary, providing a warning. We made three of these heavy seeding experiments. I quickly walked to the other two. In the second, there was much gray goldenrod nearby, but none in the heavily seeded area. In the third, it was almost the opposite; though there was only a little gray gold in the heavily seeded area, there was none at all outside of it. This contradiction reminds us of the difficulty of generalizing from a few experiments. Yet how many decades-long experiments can we afford to do before we make decisions? We do the best we can. I walked on to another experiment, to see what that one might suggest.

This experiment was a different kind. Here we started with one of the site's original patches of big bluestem. (It was almost the only plant growing in that patch at that time). A path cut through the middle of it - dividing it into two plots. On both sides of the path we seeded conservative species. (We didn't bother to seed gray goldenrod; our first notes list it as common in most places already.) On the west side we scythed (mowed) the big bluestem a couple of times a year, to keep the heavy grass from providing dense shade. After seeding, we did nothing to the east side of the patch - except for the burns of course. Then we watched for many years without noticing much difference. Now I wondered, how would it look in 2016?

The path is the dark vertical line. It seems like gray goldenrod thrives on both sides,
but we scythe the trail edge to keep the trail open, so the true experiment starts a meter or so back from the edge. 

On the east (un-mowed) side, there is no gray goldenrod and relatively little diversity.
(There is some prairie clover and one rigid goldenrod in bloom, but overall, dullsville.)

In contrast, the mowed side looks outstandingly better. Not only thriving gray gold and prairie clover,
but - if you blow up the photo and look close - tons of prairie betony, asters, bush clover, cream gentian,
lady's tresses, and general joy and happiness. 

So perhaps that mowing of the over-dominant big bluestem was a success here. And perhaps gray goldenrod is an easy-to-see indicator of surviving diversity. Perhaps losing it suggests the need to ask questions and perhaps consider different options in management strategies.

But I worried that I was making too much of too few data points. One check is the formidable resource of Floyd Swink's lists of associates. As I read through the species he most often found with some high conservatives, I had increasing doubts about my theory. I chose dropseed, cream false indigo, both prairie clovers, prairie coreopsis, prairie gentian, and prairie violet. Gray goldenrod was listed as an associate for none of them (though rigid goldenrod turned up repeatedly). 

Did that close the book on my hunch? Not quite, for example I also remembered a passage in Swink and Wilhelm that was probably written by Wilhelm:

“Northern Illinois prairies have been so completely obliterated over the last 160 years that there is no telling what the full contingent of native plants may have been on our loamy and upland prairies.”

And I had another check. My vague memory was that the best parts of Somme Prairie Nature Preserve included gray goldenrod. This original prairie is just across the river from Somme Prairie Grove - and our main model for what species might have grown in the prairie patches there. 

When nature raises questions, it's so handy to have a fine prairie so near. (In his most recent study, Marlin Bowles found Somme to be one of the two best quality mesic prairies in the Chicago Wilderness region.) So I made the pilgrimage to quality - to see what it might tell me.

At Somme Prairie there are four little Grade A (very high quality) prairie patches. They total only about three acres. But they're vastly more important than the other seventy acres. I have too much data in my head. I really couldn't remember what they'd look like, this time of year.

In the Grade A prairie, throughout the best of the best, I saw gray goldenrod by the thousands.
Just one more species in this grand and humbling diversity. With the best of associates.

I am reluctant to go to the Grade A areas too often. There's a "Heisenberg's Uncertainty Principle" here. If enough people stamped around sufficient to study everything we need to know, the prairie would be badly degraded. Perhaps we should study it with drones, but I digress.

You might think that one of the more conservative goldenrods would characterize very high quality mesic prairie. But clearly not here. And when I looked for the very most conservative plants, what did I find?
Here, where the dropseed grass is thickest, gray goldenrod is in every square meter.
In the green cage is a clump of prairie lady slippers. This is quality. 

Here the gray goldenrod is coming right up through a cream false indigo (gray leaves) as this early plant senesces for fall.
No space is wasted. This too is quality. Also visible here are prairie betony, wild quinine, rattlesnake master,
prairie dock azure aster, little bluestem, and puccoon. 

For now, I'm ready to believe that gray goldenrod is part of the diversity we want to conserve at Somme, and an indicator of a possible problem (or perhaps I should write "incompleteness") where it drops out. 

I wonder if one of the experiments we should be doing with the restoration of degraded remnants is to seed initially with some of the less dominant conservatives ... and hold off until later with the dropseed, lead-plant, New Jersey tea, and other potentially over-dominant species. Hmmmm. I suppose that would mean coming up with a list of what those are. Would we want to agree on such a list? Or perhaps let one hundred flowers bloom? And many interested people try different lists?

I'm not worried about losing the gray goldenrod for its own sake. Its windblown seed will bring it back when (or if) the community regains true quality. But I'm interested in this species as an indicator of two ecosystem states. First, a degraded prairie with a lot of gray goldenrod (and, for that matter, heath aster, bluegrass, daisy, carrot, and pussytoes) is a good candidate for restoration by burning and conservative seeding alone.

The other state is a state of grace - very high quality. When the prairie has recovered to the point that there's room for the diverse little species of summer and fall, we have maintained or restored a quality ecosystem.