CHAPTER 3
When the white people settle on the barrens or near them, the Indians recede, fires are seldom seen, a young growth of trees, healthy and vigorous soon spring up, far superior to the stinted growth which the frequent fires have scorched, and the barren assumes the appearance of a timbered country.—Bourne 1820
Thus the prairie-forest conflict probably has continued for many centuries, though the scene of action has shifted.—Cowles 1928
[T]he exact limits of the several prairies can never be set, and the boundary lines drawn on any map can be general approximations.—Weaver and Clements 1938
In the pioneer days the eastern boundary of the grassland was a broad belt in which patches of prairie and forest formed a great mosaic.—Gleason and Cronquist 1964
Within the transitional zone [tallgrass prairie] no single set of environmental factors explains the mosaic pattern of vegetation. The environmental factors influencing the vegetation operate in concert, with the relative importance of each factor and the interactions of these factors varying in time and space.—R. C. Anderson 1983
Almost everyone who has tried to map the grasslands has provided a somewhat different set of terms and mapped boundaries.—Johnsgard 2001
IN ALMOST EVERY PRAIRIE I know today, the edges and boundaries are clear, sharp, and distinct. There’s often a fence or a line of signs stating that the prairie is owned and managed by a state Department of Natural Resources, the US Fish and Wildlife Service, The Nature Conservancy, or similar entity. In one step I can go from prairie to something else, usually corn or soybean stubble.
Likewise, we know exactly what the state of Iowa looks like. By itself or shown in the context of surrounding states, Iowa has a unique shape. We can say the same thing about Minnesota, Wisconsin, Indiana, Illinois, Missouri, and Kansas. Each state has distinct and easily recognizable boundaries. On Iowa’s north and south, the boundaries are arrow-straight lines running east and west. On the east side there is the Mississippi River while the western border is delineated by the Missouri and Big Sioux Rivers.
In contrast, if it’s hard to define the prairie itself, it may be even harder to define the boundary on a map. While researching this book, I found scores of maps of the tallgrass prairie. Unlike Iowa, where every map is the same, each map of the tallgrass prairie is a little different because the maps were drawn at different times, at different scales, or with different assumptions.
To complicate the issue even more, grasslands have an image problem. Most mapmakers come from forested regions. Their maps of forests are often detailed: oak-hickory forest, maple-basswood forest, riparian forest, etc. Grasslands are simply labeled “grasslands.” Many mapmakers describe grasslands as treeless, but almost no one describes forests as grassless (Kuchler 1954; Malin 1967).
This is where mapmaking comes in. Mapmakers like hard, thin, and preferably straight lines, such as the border between Illinois and Wisconsin. The maps ecologists make rarely have straight lines and it’s really hard to draw a hard thin line on a map of habitats or ecosystems. Most ecologists would probably draw broad, fuzzy, wiggly lines instead of thin, hard, straight lines.
To an ecologist, those lines separating one type of vegetation from another are called ecotones. An ecotone is the area where two habitats come together, such as the prairie-forest ecotone. How to draw that ecotone, how wide to draw it, whether it should have hard or fuzzy edges, whether the line is straight or wiggly, are perennial problems for both ecologists and cartographers.
Some have argued that the entire central grasslands are just a boundary between the dry deserts of the west and the humid forests of the east. Others argue that the tallgrass prairie is a boundary or dynamic tension zone between the grasslands of the Great Plains and the eastern deciduous forest.
It is here [Iowa and Illinois] that the tension line between grassland and woodland is more in evidence and that the prairie problem is most acute. (Cowles 1928)
The climatic region coincident with the prairies is actually a broad boundary zone between steppe and forest. (Borchert 1950)
Some maps don’t show any prairie to the east of the Mississippi River. Wisconsin, Illinois, and Indiana are labeled “prairie-and-oak transition” (Savage 2004). Likewise, we can describe western Indiana, almost all of Illinois, western Wisconsin, and much of Missouri as the “prairie-forest transition” (R. C. Anderson 1983). According to these descriptions, Illinois, the Prairie State, doesn’t have much prairie. Others will say that Illinois and Indiana are where the grasses reach their tallest heights and where the name tallgrass prairie is most deserving.
Probably the two most recognized vegetation maps of the tallgrass prairie are from Transeau (1935) and Kuchler (1964). These two maps don’t line up well at all. First, they are basing their maps on two different assumptions. Transeau’s goal is to “locate more accurately the eastern extension of the prairie at the time of settlement.” Transeau’s map famously describes the “prairie peninsula,” which was a broad grass intrusion into a forested region with the areas to the north and south of this region covered in forest.
Alternately, Kuchler’s goal was to map “the vegetation that would exist under the present climate if man were removed from the scene and if the resulting plant succession were telescoped into a single moment.” Much of what Transeau labels “Prairie Peninsula,” Kuchler labels “Mosaic/Bluestem Oak–hickory.” In essence, he’s saying that most of what others map as the eastern tallgrass prairie is a transition or ecotone between grassland and forest. Note that Savage (2004) and R. C. Anderson (1983) also refer to the peninsula as a “transition.” Is the eastern tallgrass prairie an ecosystem or just a meeting and mingling of other ecosystems?
Perhaps the most interesting words in those statements are Kuchler’s “if man were removed from the scene” and Transeau’s “at the time of settlement.” Transeau explicitly captures a snapshot in time, the beginning of the Euro-American settlement period. Kuchler’s removal of humans from the scene is probably a reference to fire, implying that without Native Americans there might not have been a tallgrass prairie, or at least it wouldn’t be as extensive as it was. One of the themes of this book is that there was or is no point in time when humans were not actively involved in the tallgrass region. Another theme is that the prairie and prairie boundaries are very dynamic.
Figure 2 is an imaginary landscape where dots represent trees across the prairie-forest border. Imagine you’re a mapmaker and you’re allowed to draw one straight line dividing prairie from forest. Where do you draw that line? Next, you can draw one line, but it can have a gentle curve. Last, you can draw a line and make it wiggle as much as you want. Where did you draw the lines? Let’s now say that we can identify an oak savanna, scattered trees, in the boundary between the open forest and closed canopy forest. Now you can draw two lines, dividing prairie from savanna and savanna from forest. Where do those lines go? Imagine showing several people this diagram and asking each to draw a line on it. What are the chances everyone’s lines perfectly agree? What does that say about how easy it is to identify the prairie-forest border?
Can a prairie be defined as a grassland with “less than one mature tree per acre” (Curtis 1959)? Doesn’t that seem arbitrary? What about one tree per hectare, or per forty acres? Clearly, mapmaking and defining boundaries require some judgment calls.
There are a couple openings in the eastern side. Are these small enough that they are just gaps in the forest or are they large enough to be considered prairie openings? There is a small gap in the northeast and a larger gap in the southeast. Do you include one but not the other? How many trees does it take before a prairie becomes a savanna? When does a savanna get so dense it becomes a forest? How big does a gap in the forest have to be before it becomes a prairie opening?
FIGURE 2. In this representation of a prairie-forest border each dot represents a tree. Where is the best straight line that divides the prairie from the forest? Is there a definable savanna between the prairie and the forest?
Figure 2 could represent an area one hundred yards wide or one hundred miles wide. Transeau (1935) described the prairie-forest boundary as “these borders are often miles in width” and two pages later as “at most a few rods in width.” Within the same sentence, Gleason and Cronquist (1964) write “individual boundaries between forest and grassland were commonly sharp . . . but the boundary between the two provinces as a whole was not.” So, the boundary between prairie and forest is both wide and narrow, sharp or not. As we’ll see throughout this book, the answers to many questions about the prairie depend on a person’s perspective.
The question of scale is also important. Imagine you are mapping vegetation while orbiting the earth in 1800. You would probably draw a fairly general southwest-northeast running diagonal line through northwest Indiana dividing prairie from forest. Now imagine flying over Newton County, along that border, at fifteen thousand feet. You could draw more lines and they would curve and wiggle much more. You see more detail than from orbit, but you’re still missing a lot. Now imagine walking across The Nature Conservancy’s Kankakee Sands Preserve. You could map the vegetation in great detail. Each of those maps is valid, although each of those maps will be quite different.
If the eastern boundary against the trees was difficult to define and fluctuated dramatically over time, then the western boundary against the mixed-grass prairie was very difficult to identify and very dynamic. In fact, the differences between grassland types may just be “arbitrarily designated” (R. C. Anderson 2006).
A series of dry years shoves all boundaries eastward, and wet years push them west again. (Gleason and Cronquist 1964)
The Great Plains thus end as they begin, not with a sudden bang but with a quiet whisper. (Johnsgard 2003)
Chapter 2 demonstrated how dynamic the prairie vegetation was since the glaciers retreated. The boundaries of the prairie have been and continue to be very dynamic. Over the last several thousand years, the prairie probably stretched much farther east than Transeau’s map describes. One problem with trying to draw a line between the prairie and the forest, or prairie and plains, is that the line is always shifting. These shifts didn’t happen at millennial time scales, they were fast enough that people saw them over the course of decades. Note that people were describing these changes in the early and mid-1800s, long before most Euro-American settlers reached this region.
The ravages of fire amongst it has been very considerable; and in this part, the prairie, was visibly gaining on the woods. (Thomas 1819)
That the annual conflagrations have prevented the growth of timber on the prairies, is clearly proved by the very vigorous growth of young wood which takes place along their margin, wherever the fire has been kept out for a few years. (Oliver 1843)
In many cases, as this prairie-forest boundary fluctuated over time, some species were left behind. Thus, we have prairie species left behind as the forests moved west and forest species left behind as the prairies moved east. Are prairie openings in the forest indicators of a once larger prairie or are forest groves in the prairie indicators of a once larger forest? The answer is yes . . . probably . . . it depends.
The occurrence of scattered colonies of prairie species beyond the eastern limits of the province may indicate a former more extensive range of the prairie. (Gleason 1909)
[T]he prairie groves may be in many cases remnants and not recent invaders. (Bray 1957)
When anyone draws any map of the Plains, prairies, and forests, it needs a time stamp. It doesn’t make sense to draw a line dividing prairie from forest, or plains from prairies. It does make sense to say that this is the prairie-forest boundary in 1492, or 1836, or whatever reference point you choose.
We have a valuable tool for reconstructing historic vegetation patterns in the Midwest, but that tool can be misleading. That tool is the General Land Office Survey that mapped vegetation across the Midwest, county by county, township by township, square mile by square mile in the first half of the nineteenth century. Some of the most useful data the surveyors collected were witness trees at the corners of each square mile. Surveyors recorded the size and species of these trees and wrote general descriptions of the vegetation. However, they were catching only a snapshot in time.
Some of the earliest French explorers left accounts of the vegetation and wildlife in the 1630s and earlier. In the 1830s and 1840s, surveyors measured and described the vegetation. In those two centuries, diseases decimated Native American populations while other tribes were displaced from the eastern part of the continent into the Midwest. At least eighteen different tribes moved into or through Iowa during the historic period (Mutel 2008). We can’t just say Native American. There were dozens to scores of tribes and cultures in various times and places within the tallgrass prairie region. Presumably all of these changes would have had dramatic effects on the amount of fire Native Americans were using (Mann 2005). Changes in fire probably led to changes in land cover, presumably more trees with less fire. If there can be noticeable land cover change, forests invading prairie, over a couple decades as described earlier, how much change could happen between the 1630s and 1830s?
If you watched television in the late 1970s, the word “prairie” probably evokes images of a little house and people named Pa, Ma, Mary, Laura, and Carrie. However, the first book in Laura Ingalls Wilder’s series was titled Little House in the Big Woods, which was near the city of Pepin along the Mississippi River in the Driftless Region of southwestern Wisconsin. The Driftless Area today is well known for its extensive forests (Swenson 2009). An analysis of the General Land Office Survey records concluded that the region was “a landscape dominated by savanna and a variety of oak communities” (Shea et al. 2014).
In 1766 Jonathon Carver described the land just south of Pepin near today’s Prairie du Chien, Wisconsin, as “the country round me appeared like a meadow full of hay cocks all covered with grass” and “neither trees nor stones except a few elms and maples on the banks of the river.” He described the area around Pepin as “these mountains are covered with grass with here and there a small tree. The valleys have some groves of trees” (Parker 1976).
When describing the land along the Mississippi between the Wisconsin River and the modern-day Twin Cities, Featherstonhaugh (1847) frequently mentions prairie and tall grasses. Traveling that same route, Catlin (1844) describes “the whole face of the country is covered with a luxuriant growth of grass . . . a carpet of grass, with spots and clusters of timber.”
Are the General Land Office Survey records providing an accurate account of the vegetation? Yes, for the arbitrary point of time the survey was conducted in each township and county. That’s not to say that the area always looked like that. Clearly the landscape and prairie-forest border could change relatively quickly and quite dramatically. Was the Driftless Region an open grassland, an oak savanna, or a big woods? Obviously, we can’t take some anecdotal historical accounts about specific locations and reach grand conclusions about entire regions. However, these accounts do paint three very different pictures of this region. Perhaps the next interesting question is “should we be managing these areas for prairie, savanna, or woodland, and what is the justification for our decision?”
Personal Geographies
CHEMISTS OR MICROBIOLOGISTS will disagree with this statement, but I just don’t see how anyone can become emotionally attached to a beaker of chemicals, fuzz on a petri dish, or lines of DNA spread out on a gel. Granted those may be connected to a disease they are trying to cure, which is obviously important, but that’s a step removed.
However, it’s hard not to feel an emotional tug when opening your fingers and watching a songbird fly from the palm of your hand with a new band on their leg. It’s hard not to feel something when watching an upland sandpiper land on a fencepost and fold their wings, defining the word grace. It’s hard not to feel you’re in a special place when you’re staring through a camera lens at a western prairie fringed orchid.
Even more important is a connection to place, specific spots on a map. Every conservationist has these spots. In “Wilderness Letter,” Wallace Stegner talks about a geography of hope. Although he was referring generally to “wild country,” every dedicated conservationist has a personal geography. These are special places for any reason or number of reasons. There may be a unique geological feature. It may be especially scenic. It may be a place where you first found or have only found a particular wildflower. It may be memorable for the person or people you were with on the first or subsequent visits. By middle age, most of us should have a catalog of these places. Some we share with others, such as a state or national park. Some are circles on our personal maps we like to show to friends. And some places are so personal and special we don’t share them with anyone.
I first visited Smith Pioneer Cemetery the summer between my freshman and sophomore year of college. That will always be my first prairie remnant. Shiloh Pioneer Cemetery and Spinn Prairie, both in west-central Indiana, are special in their own way and I have specific memories of both. Those memories include people I visited the sites with, as well as plants.
The following fall semester I visited Green Oaks Prairie. It’s been almost three decades since I was last there, but the map in my head still has plenty of details. It’s as if the last visit was last weekend.
From there it was Konza Prairie in the Flint Hills of eastern Kansas. And while Konza itself is special, there are also special places there, special for a number of reasons and probably special only to me.
After eight years in Kansas the dog and I moved to the Agassiz beach ridges of western Minnesota. Within a ten-minute drive from the house there were at least ten publicly owned and protected tracts of grassland that contained native prairie. I moved away from there almost a decade ago and don’t get back enough.
Next, we lived in south-central Minnesota. Here the pup and I found a number of small hillsides, most less than an acre, some much less than an acre, on public lands that weren’t mapped as being native prairie. Although heavily dominated by brome, the forbs we found in these places told us they had never seen a plow. Now we live well into the forest side of the prairie-forest border. Yet we still know a number of roadsides and railroad rights-of-ways where prairie species have hung on.
I’ve only been back to Kansas once in twenty years. We still get back to our prairies in northwest Minnesota ever year or two. And I still know within inches where the clumps of ladies slippers orchids are in each of the wet prairies and which hilltop prairies have the most prairie smoke.
At the same time, I can list several sites that used to be covered with high quality prairie. These days those acres just produce corn, gravel, or trophy homes. From Indiana to Kansas to Minnesota, the geography of my life has been a rough triangle that approximates the tallgrass region. My life is bounded by bluestem.
Graduate students are taught that scientists must be these cold, rational beings. Impossible. Conservationists are people with lives and relationships and loves. Some of those loves are locations, and if you’ve been doing this long enough some of those locations are losses.