Andrew H. Williams, 1630 Linden Dr., Entomology Dept., University of Wisconsin, Madison, WI, 53706, paper 3 of 3.
A NEW PARADIGM FOR PRAIRIE MANAGEMENT: AN ESSAY
Andrew H. Williams
Abstract: Prairie is managed with various goals in mind: education, roadside beautification, etc. With such limited goals, we can continue to manage prairie by focusing on few key species and using the information that we have. But where conserving biodiversity is our goal, this paradigm fails. The great diversity of prairie invertebrates and our ignorance of the life histories of most of them requires that, in our management planning, we consider what we do not know as well as what we do know. To lessen the risk of losing species from the often tiny patches of prairie habitat that remain, we must manage these sites now, rather than delay further awaiting more information. And we should spread the risk inherent in anything we do in both space and time. This is an essay, the fruit of my decade in Wisconsin prairie conservation.
Prairie is managed with various goals in mind: education, roadside beautification, duck nesting habitat, etc. With such limited goals, we can continue to manage prairie by focusing on few key species and using the information that we have. But where conserving biodiversity is our goal, this paradigm of science-based management fails.
Prairie is a biotic community, not simply a plant community. Though we recognize it most easily by its characteristic plant species, plants actually comprise a minority of the life forms present.
Some years ago, at a time when I focused on plants, I resented the weevils feeding on the wild indigo (Baptisia spp.) seeds being collected for restoration plantings. Now, I focus on insects, and realize that any prairie plant is a stage on which various, marvelous animal dramas take place. A native plant enriches a given prairie simply by being there, but it can contribute far more to the biodiversity present by supporting a diverse array of animals.
In my research on the various fauna using the plant marbleseed (Onosmodium molle Michx.) (Williams 1996, 1999a), about 120 species used this 1 prairie plant in different ways. Several are utterly dependent upon it. If you were to lose marbleseed from your site, you would also lose these few specialist insects. This is not exceptional, but typical.
In my research on the fauna overwintering in stems of 20 species of prairie plants (Williams 1999b), an average of 15 different species of arthropods used the stems of each of these plant species as a winter refuge. Among these animals were many different parasitoids, tiny wasps that develop within the bodies of other insects.
Our knowledge of insects is many decades behind our knowledge of plants. For example, in 3 timely visits to your prairie remnant, I could produce a list of the plants growing there, a list that would include 95% of the flora at a minimum. But if I were to devote 10 years of my time and arrange for help from dozens of insect taxonomists I could not produce a list anywhere near as representative of the fauna on your prairie remnant.
Another example of our ignorance of prairie insects is that most of what we know about insects that require prairie is based on the food plant preferences of herbivores. Many insects are very particular about what plants they use as food. But these herbivores are close to the base of the trophic pyramid. We know essentially nothing of the parasitoids high on the trophic pyramid. One of the few things we do know about them is that species are often restricted to a very narrow range of insect hosts.
Just because a particular plant species is present on your prairie does not guarantee that the specialist fauna it may support can survive your management activities. The flush of growth and reproductive activity shown by many prairie plants following a fire reflects, in part, the suppression of insect activity that previously had slowed the plants’ growth and often “disfigured” the plants. But our goal is not to convert the wild prairie to a garden of prairie plants. Try, instead, to conceive of the “disfigurement” in prairie plants as proof of higher biodiversity and focus more closely on the little animals that contribute so much to making your prairie such a wild, beautiful and fascinating place.
If you stand in prairie during daylight hours, quietly scanning the stems and leaves and flowers nearby, you will usually see many kinds of insects. Each of these has a different life history, a different story to tell, and most of these stories are, as yet, unknown to us.
Go out on your prairie at night with a flashlight. Most flies, bees and wasps will no longer be flying, though you’ll find them sleeping on leaves and flowers. The sounds of their wings will be gone, but other sounds characterize the night. Crickets and katydids dominate the night symphony but there is a great diversity of small voices as well. Stand still and peer closely at the plants around you and you’ll probably see many different insects. Warm, humid, windless nights are best.
Turn off your light and look to the night sky. The stars, shining in darkness, are tiny facts. This star is the flowering date of hoary puccoon (Lithospermum canescens (Michx.) Lehm.) on your prairie. That star is the knowledge that some prairie insects cannot live where they find no refuge from fire. This star is that compass plant (Silphium laciniatum L.) soon vanishes from a site where continual grazing by cattle occurs, and that star is that marbleseed generally benefits from grazing (Williams 1996, 1999c, 1999d). There are very many stars.
Astronomers learned that by observing from mountaintops, more stars were visible than from sea level. By using a telescope, one can see more stars than with the naked eye. From the Mir Space Station, 4 times as many stars were visible than from Earth’s surface. As time has passed and by our expanding our means of inquiry, our common knowledge has increased — our common ignorance has decreased. Out of the darkness more stars appear.
What of the moon? The moon is your own capacity to winnow pertinent information from the mass of our common knowledge. Your capacity waxes and wanes over time as you encounter more information, as you learn to process information in new ways, as the exigencies of your life intervene — the time you can make available to think, the budget your employer makes available to you, the conflicting demands of your family. Even at its brightest, moonlight is dim. Though the sky may be ablaze with stars, each of us has a very limited ability to make use of this abundant information.
This, too, should motivate us to use caution in prairie management. Not only is our common knowledge, as yet, very limited — the sky is largely darkness — but no land manager, no professor, no committee, no agency can make very intelligent use of the small bright pieces of common knowledge they perceive.
As one travels about the Midwest, where prairies once dominated the landscape, it’s difficult today to find even tiny prairie remnants. Some of us regret the excesses of our modern culture which, in concert, have destroyed nearly all of the wildness in our environment, including the prairies. Yet we all participate in this destruction, not only through our daily decisions in this consumption-crazed culture, but even in our efforts at prairie conservation. Prompted by our pain at witnessing the destruction of our beloved wild grasslands, we hurriedly repeat the same mistake made by conservationists who preceded us by falling prey to excess. We grasp at “expert” advice and strive to do the best we can which, in our urgency, we mistakenly conceive as finding and engaging the right management strategy. Ironically, we are missing the very opportunity we want so much to seize.
There is no right way to manage land. Our common ignorance and our personal ignorance assure the inevitability of our making mistakes that erode the biodiversity we are trying to conserve. The wisest strategy is to use different tools at different times in different places. Rather than apply the same management regime across all of the sites we manage, we should be building variation into the management plans for different sites, and often for different parts of a single site. In short, it’s best to hedge our bets by spreading the risk inherent in anything we do in both space and time.
Grasslands naturally occur where several factors combine. Topography, substrate and climate are factors we cannot control. Whereas, grazing by large mammals and fire are factors we can largely control.
It’s easy to see where grazing is applied to the landscape in ways detrimental to the native prairie that once dominated many pastures. Most of us see grazing misapplied so often that we forget that grazing by large mammals is a process integral to wild prairie. This has led to grazing being taboo among prairie managers in Iowa, Wisconsin and Illinois (Williams 1996, 1997, 1999c). This utter rejection of grazing is an over-reaction — excess.
The importance of fire to our native grasslands was rediscovered recently. Prairie managers accepted fire, based on how it affects many plants, and have been vigorously applying it to prairie remnants. In Wisconsin, where I come from, some employees of the Department of Natural Resources still burn entire prairie remnants at once. Fire is a powerful and useful tool, but the vigor with which we often apply it, in light of our ignorance of its effects on most prairie species, particularly the invertebrates, is an over-reaction — excess.
Though I used to apply fire more vigorously, I’ve come to see how little we understand. So I have changed my behavior.
Given the rate at which prairie remnants are disappearing and given the risk of losing species from the often tiny patches of prairie habitat that remain, it is essential that we resist the temptation to wait until we have more information. We must act now, thoughtfully using what information we have as well as considering that information we lack. We must act. My own belief is that grazing by large mammals and fire are appropriate tools and that, because these influenced prairies in concert long ago, it’s best to include both of these tools on most of the sites we manage.
I appreciate the knowledge we can gain by focusing narrowly on parts of the prairie ecosystem. For me, nothing is as thrilling as discovery! But our scientific perspective of recent years is yet another example of excess. It has led to a process for making management decisions that, by discounting our ignorance, fails to serve our goal of conserving prairie biodiversity. We will be more successful in this effort by accepting the limits of our intellect, by accepting our fallibility, by approaching our work with greater humility, by conscientiously trying to lessen the risks inherent in any of our management activities and by letting ourselves learn while not focusing at all.
I am most grateful to R. Christoffel, G. Eldred, D. Schlicht, J. & R. Sime, A. & S. Swengel, D. & E. Williams and D. Young, among others. These people, especially, have contributed toward my growing awareness of issues in prairie conservation over the last decade.
Williams, A. H. 1996. Conservation of the plant Onosmodium molle A. Michaux (Boraginaceae) and the beetle Longitarsus subrufus LeConte (Chrysomelidae) in Wisconsin. MS Thesis. University of Wisconsin, Madison, WI. 424 pp. (Available from: University Microfilms, Ann Arbor, MI; Order #1382083.)
Williams, A. H. 1997. In Praise of Grazing. Restoration & Management Notes 15(2):116-118.
Williams, A. H. 1999a. Arthropod fauna using the plant Onosmodium molle in Wisconsin. In The central Nebraska loess hills prairie, North American Prairie Conference Proceedings. 16:165-171. J. T. Springer (ed.), Dept. of Biology, Univ. Nebraska, Kearney, NE.
Williams, A. H. 1999b. Fauna overwintering in or on stems of Wisconsin prairie forbs. In The central Nebraska loess hills prairie, North American Prairie Conference Proceedings. 16:156-161. J. T. Springer (ed.), Dept. of Biology, Univ. Nebraska, Kearney, NE.
Williams, A. H. 1999c. Importance of cattle in conservation of dry prairie in Wisconsin. In North American Prairie Conference Proceedings 15:249-250. C. Warwick (ed.), Natural Areas Assn., Bend, OR.
Williams, A. H. 1999d. Inventory of Onosmodium molle in Wisconsin: historic status, present status, and future prospects. In North American Prairie Conference Proceedings 15:251-255. C. Warwick (ed.), Natural Areas Assn., Bend, OR.