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Tuesday, May 16, 2023

Blunt Answers to Nine Questions about Saving Oak Woodlands

By Christos Economou, Matt Evans, Eriko Kojima, and Stephen Packard

We have been too cautions. The increasingly-rare plants and animals of a hallowed community have suffered from reverence and indecision. 

A healthy woodland is now rarer than a healthy prairie or savanna. But we've been blind. 

The previous conservation strategy – to leave the woods alone – is a bad failure. Now this region's only Globally Threatened (G1) community is oak woodland on rich soil, formerly our major forest type.

Most surviving remnants are losing species fast. Don't be fooled by a "rich looking" spring ephemeral flora. In the photo below, the ground will soon be bare. The summer and fall flora did not survive here, nor did the pollinators nor other animals that depend on the hundreds of summer and fall plant species.

Or, below, with most species now gone, what's left? Bur oaks, not reproducing, nearly all plant and animal diversity under their canopies smothered by buckthorn:

A long-degraded woodland - before restoration

Same woodland - with restoration under way. Spring flora mixed with summer and fall flora. Many animals returning. See detailed spring and summer photos below.

Spring - after thirty years of restoration - turf under bur and Hill's oaks.
May 6
Species in the photo above include rue anemone, wood betony, golden Alexanders, toothwort, thicket parsley, Pennsylvania sedge, beardtongue, starry campion, awned wood grass, large-flowered trillium, trout lily, cow parsnip, meadow rue, and wild geranium. Only two of these species are spring ephemerals. 

Summer detail in same area.
August 11
Admittedly not all that perfect a photo, but the best we could find. 
Illustrating that healthy woodlands have diverse flora blooming all growing-season long.
Species in the photo above include big-leaf aster, awned woodgrass, cow parsnip, silky rye, woodland sunflower, carrion flower, and purple Joe-Pye-weed. 

Healthy, sustainable, reproducing, natural woodlands have barely been studied because they barely exist. Though there is little study of it, woodlands are probably losing important and irreplaceable 
genetic alleles even faster than species. Most studies tell us little about long-term best management. Fragments of ancient oak woodlands on rich soil survive in the Midwest and perhaps in few other places. We look for life on the Moon and Mars, but we let biodiversity fade out on Earth.

If we want to be good stewards of woodland biodiversity … should we thin trees? … burn every year? … burn every five years? … plant no seed? … plant local seed only? … plant seed from further south? For answers, we’d prefer not to rely on just theories. We need data that we don’t have. For most questions the best we can do is to rely on the informed judgment of people who do their best to be objective and who’ve compared various initial approaches. Getting statistically significant and actually useful data takes more years than most scientists have time for. At this time, controlled experiments are not answering most practical questions. 

This post is written for three (or possibly four) audiences: 1) conservation staff who want to conserve oak ecosystems, 2) volunteer stewards, 3) private owners of woods, and 4) if we might be so lucky, researchers who’d like to design experiments to answer basic woodland biodiversity conservation questions. 

Nine Questions for Those Who Care for Oak Woodlands
1. Is it good enough to just burn? 

2. Is it good enough to just burn and control invasives? 

3. Under what conditions should we broadcast seed? 

4. Should we cut native trees? 

5. What is the role of shrubs in woodlands?

6. Should we use herbicide?

7. Should we control deer?

8. What does it mean to employ holistic approaches? 

9. Do sites need both volunteers and staff?

Do the answers given here reflect sound science or expert judgment? See Endnote 1. The discussions below certainly reflect our own experience and observations. Many people have used different approaches, and their experiences should be considered too. 

1. Is it good enough to just burn?

In most cases, the answer is no. Here’s a scary case study: 

When we discovered the site in the 1980s, about ten acres of it came to be considered the finest "open oak woodland" of "closed savanna" we knew. People came from distant states to study and admire. Here (in a site being unnamed in this account) light-loving species like purple milkweed and white false indigo were common. Yellow ladyslipper, cream vetchling, and scarlet painted cup added to the sense of quality. Commissioners and staff of a local conservation agency, to their great credit, acquired it and have burned it on average every second year ever since. We took start-up data in 1986 (as part of the process that resulted in the Illinois Nature Preserves Commission first approving woodland burns). That monitoring was followed up three times at roughly ten year intervals since then.

The density of tree trunks has doubled. Most of the additional trees are young hickories. Although the site still appears wonderfully rich, many of the conservative open-woodland species that require the most light (for example purple milkweed, false indigo, and painted cup) are gone or much reduced. 

Shade from buckthorn had decreased, thanks to control of that species. The shade increase came from species native to the site. Some argued that, given regular burns, what we were observing was not a problem – but simply nature – and we should not “play God” with native species. Others argued that the burns must have been conducted on days that were not hot, dry, or windy enough to maintain the ecosystem and its biodiversity. If necessarily-restrained burning didn’t maintain enough sunlight to conserve the biota, then perhaps the thinning of trees was needed. Indeed, the latter argument won out in 2020, and trees are now starting to be thinned there, a bit. 

A study from Iowa by Wilhelm and Rericha makes a strong case for the success of both annual burning and thinning over-dense trees. 

Today most oak woodlands under "conservation management" are too dark. (For more perspective on this, see Discovering Oak Woodland: history and theory.) We know they are too dark because the canopy bur or white oaks are not reproducing, because many animal and plant species are dropping out, and because the populations of those declining species rebound when light is increased by fire and tree removal. A lot of the insights into oak woodland conservation are new and urgent, and many conservation organizations are wisely revising their standards.  

What sorts of burns are most therapeutic, under today’s conditions?

It’s not sufficient for fire today to be natural – meaning “whatever happens is good enough.” The “prescription’ needs to be sufficient to “cure” or “repair” a long-term malady. We cannot match the often-extreme conditions of the past, but we do have to be effective. As a thought experiment, consider what natural lightning-ignited burns would have been like for millions of years. Fire for the average piece of ground would tend toward the extreme because, if lightning starts a fire on a cold wet day, that fire won’t burn a very large area. On a hot, dry, windy day a single fire might burn hundreds of square miles. 

It’s not uncommon to hear advocates recommending pyrodiversity. That is, burn at varied intervals, at varied times of year, with varied wind directions, and varied intensities. Some also recommend including burns during the growing season. We are sympathetic to these recommendations, but we don’t find them to be based on convincing science. Good science is needed. And if the prescriptions “don’t work” – that is, if the conservative diversity is being lost, then the prescription is failing.

But if the patient dies while the research proceeds, we’ve failed. We worry that managers of important sites may consider research goals to be a reason to withhold badly needed burns. The first priority is to save the patient. If an important site for woodland biodiversity exhibits shrinking populations of characteristic, conservative, rare woodland species with those being replaced by forest species (or bare ground), it’s not unreasonable to make the judgment that more fire is needed. Perhaps other, less critical sites can continue to study the long-term less-burned approach. See Endnote 2 on needed fire research.

In the case of sites that are not part of research, that is, if the site goal is just good conservation, it’s our impression that burning these days is too infrequent and too mild to do the work that’s most needed. Burns need to be safe, but that’s not the only criterion. Burns also need to be as effective as is practical. Burn crews often make the mistake of standing down on days that are too hot, dry, or windy to burn a prairie. That kind of day is very much the kind of day that produces best results in the oak woods. On such days, burns can be fully safe in the oak woods. Winds, fuels, and drying times in the woods are quite different from those in the prairie, and standards for safety and effectiveness for woods burning need to be distinct from prairie standards. 

2. Is it good enough to just burn and control alien invasives?

No, it’s not remotely good enough. In many better-quality woodlands, the most damaging “out-of-balance” species are not aliens. They’re native species growing out of control, like cancer cells. 

Extensive bur oak savannas and woodlands were a major part of our natural landscape. White oaks were a minor component of these ecosystems. But when the fires stopped, white oaks reproduced more readily in the increasing shade. Soon it became too dark for any bur oak seedlings to survive. At the same time this ecosystem was losing other components that depended on its bright-dappled-light: shrubs, grasses, wildflowers, butterflies, fungi, now-rare bacteria – it’s a very long list. In the early stages, most likely, vigorous burns could have restored natural diversity and function. But when species are gone, or when many occasionally needed alleles of some species are gone, they may need help to recolonize. Bottom line: White oaks are generally good, but if they make a bur oak woods too dark for its full biodiversity to survive, they are a problem. 

Or consider white oak woodlands – the other major component of our forested heritage. Yes, there was a bur oak here and there, some shagbark hickories, some red oaks, and an occasional ash or cherry, or maple tree. They were native – not invaders. But they were held to secondary status by regular fire. After protection from burns, the hickories, maples, and all grew dense and dark. White oak reproduction and associated animals, plants, and other biota then faded out. 

Certainly, if a bur or a white oak ecosystem is to recover natural biodiversity and sustainability, it needs conditions – including the amount of sunlight required for reproducing bur or white oaks and associated animal and plant species. 

3. Should we broadcast seed? 

In most cases, yes. 

There is a common belief that the “soil seed bank” is sufficient. That “bank” is largely a myth. Research by Arnold van der Valk in Iowa found meaningful seedbanks persisted in wetlands but not in prairies or woodlands. Nathan Lamb and colleagues at the Chicago Botanic Garden studied oak woodland seed banks and found little beside common weeds.  

More importantly, we’ve tested the seedbank theory in restoration, over and over. Some species increase vigor and bloom once again following brush control and a burn, but they seem mostly to be ones that were surviving as suppressed plants, rather than seeds. We have compared seeded with non-seeded areas. Indeed, we first tried the “no seeding” experiment in many forms. It did not produce much. Most plant diversity at most sites does not return without doing the work of finding remnants where missing plants survive, gathering their seed, and broadcasting it into the burned remnant ecosystem. Many plant refugee species, absent for decades, begin to thrive again as part of a rich community when their seed is restored.

Aside from the belief in the seed bank, there is a common attitude that opposes “meddling” with nature by moving seeds between natural areas. Given people’s history of detrimental meddling, this concern is understandable. For some sites to continue the experiment of discovering what comes back without assistance seems fine. But what we have seen suggests that those sites will not be the most significant biodiversity conservation sites. 

It seems especially important to have in each region at least a few “full ecosystem re-assembly” sites. In these, the goal would be to restore all species that might likely have been there (including, potentially, insects, fungi, and more) and to promote the most sustainable, genetically diverse populations possible. The intent would not be to re-create the original. Instead it would be to give the ecosystem the opportunity to reassemble its diversity in whatever way comes “naturally” now, under conditions today. Our experience has been that relatively rare conservative plants often become increasingly central to such “re-assembly” communities, as they are in the better-quality remnant natural woodlands. Without such reassembly sites, much biodiversity may be lost permanently. Though little studied, it seems reasonable to hypothesize and hope that what’s true of plants would also be true of other conservative biota. 

Perhaps the best sorts of site to choose for ecosystem assembly are large sites with diverse habitat of as much remnant quality as possible. They are the ones most likely to have a starting diversity of plants, pollinators and other animals, fungi, bacteria, and other ecosystem components.  

From how close should seeds come? There’s no one-size-fits-all answer. If we had the capacity to study it, there are certainly arguments in favor of genetic testing to determine whether there are highly-local alleles that can be preserved best by excluding plants from farther away. For comparison, we would also want to study whether adding alleles from other populations would provide species with sufficient genetic diversity that they could then adapt themselves to ongoing changes like global warming. Thus it makes sense to seek seeds from further south for some sites, exclude them from others, and compare. There is common belief that these concerns are less apt for seed of wind-pollinated plants, as pollen has long blown in from substantial distances. 

Whatever the sourcing strategy, planting into an ecosystem requires different thinking and approaches than planting into bare soil. Some principles and tips can be found here and here.  

4. Under what circumstances and how much should we thin native trees?  

The basic answer is: “Thin all species of trees sufficiently that the full biota of the ecosystem has enough light for recovery.” Many people were initially troubled by cutting any native trees at all, especially in a place reserved for nature. But research demonstrated clearly that maples and associated species were destroying the biodiversity of the oak woods, so control is now widely accepted among conservationists. But questions persist about some species, four of which are discussed below. 

Red oak, like sugar maple, is a fine tree. But not every last one contributes to conservation everywhere. Many savannas and woodlands that originally consisted of bur and/or white oaks (as indicated by the older trees and the Public Land Survey of the 1830s) today have increasing numbers of younger red oak “pole trees.” Bur or white oaks grow more slowly than red oaks in shade. As red oaks overtop them, the young bur or white oaks die. Their skeletons are sad reminders. We wouldn’t recommend eliminating every red oak from a woodland, but we should thin them sufficiently for reproduction of the old canopy trees.  

Shagbark hickory is a natural component of oak woodlands. But it’s another species that proliferates excessively in the absence of fire. It should be thinned as needed, with a clear conscience. Bitternut hickory seems to be a weedier species, less adapted to most oak woods but also sometimes proliferating explosively in the absence of burns. We retain many fewer of them compared to the shagbarks. 

Hop hornbeam is a lovely, slow-growing understory tree that many people are especially reluctant to cut. But it too is a major shade producer and in many situations it seems best to reduce their numbers substantially. In more open savannas and woodlands, the hop hornbeams seem to burn out once the fires have resumed; it may seem fine to just wait for that. But at many sites it seems best to cull many of them, to save what’s surviving underneath while we can, to expand the size of functional habitat for the species that need brighter light, as those are the species being lost at so many sites.  

Bur oak. Do we thin even them? Yes we do – especially where they have formed stands of pole trees (see next item). Many studies have demonstrated that most trees in oak ecosystems were historically much farther apart under their natural fire regime. These widely spaced trees may have supported understory herb communities uniquely adapted to their thin, patchy canopies. Today, where dense bur oaks grow together, the ones that likely lose out are the ones most in need of conservation, those better adapted to fire. We have the impression that some young bur oaks put their energies into building thicker bark and spreading branches. Side by side with them grow others that put their energies into growing taller. In the absence of hot burns, the apparently more fire-adapted oaks die out in the shade of the taller ones. If we want all the alleles, we may have to manage so as to retain some of the trees that may be the more fire-adapted ones.  

Pole trees. 

They may be maples, oaks, or most any kind of tree: all saplings grow into skinny poles when they have to compete in a dense pack of saplings. Perhaps in a natural maple forest, the end result is that “the best tree wins” and makes it into the canopy. But oak ecosystems don’t work that way. The majority of their biodiversity thrives in a dense, sunny herb layer under well separated trees. Dense pole trees don’t grow into oak biodiversity habitats in the short run, and perhaps never. It seems best to us to cut most of them. In some cases, we have left a few, which then tended to blow down sooner or later without the windbreak of the dense pack surrounding them. They’re malformed. It may be best to cut all of them and let mostly the principal canopy species resprout. Then we (or, preferably, fire) keep them thinned enough that a few better-adapted individuals win out.  


An especially good way to open the canopy in many situations is to forget herbicide and girdle. By cutting off the phloem and leaving the xylem (see diagram) we allow the roots to keep feeding the leaves and branches but prevent the miracle of photosynthesis from sending needed products down to the roots. Then the roots die, as does the rest of the tree, after a year or three, depending on the size of the tree and roots’ energy storage. 

Girdling does not work for some species (notably black locust and tree-of-heaven). If we try the trick of girdling, those species don’t fall for it. They put up new shoots from their widespread roots, massively. For these we use a technique called “frilling” or “chemical girdling.” In this case we saw or chop a circle around the trunk and put herbicide into it. If the bark is thin enough, we can just “basal bark” it; that is, rubbing herbicide on thin bark at the base of the tree can kill it. But no-herbicide girdling lessens the chances of negative side-impacts of the herbicide.  

The basic issue in this question #4 is: How open a canopy is open enough? Our answer is that we need every part of the continuum. So far as we know, every part of the shade continuum from prairie to forest was part of biodiversity. So we want all degrees of openness. But in most cases of oak savannas and woodlands, we now mostly lack the more open components, so we work hardest to restore those.  

Savanna (top), Woodland (middle), and Forest (bottom, oak forest to the left).
For biodiversity conservation, we want to maintain substantial areas representing every point along the oak savanna-woodland-forest continuum shown above. 

With remnant areas, one good approach is to decide openness targets on the basis of old trees. Many sites still include trees that are three hundred years old. The structures of these trees represent ecosystem conditions as they were before Europeans turned off the fire regime. If such trees show the remnants of large, spreading limbs, that tells us that those trees were spaced well apart. If they are bur or white oaks, and we want them to reproduce naturally, they need much more light than they are getting on most conservation land today.  

5. Should we plant shrubs as part of restoration?  

In most cases, probably not. 

Shrub thickets were part of the natural landscape. We know that because of some written records (although these are rather few). Many animals and plants are adapted to shrub communities.  

We also know from written records that large areas of prairie and woodland had few or no shrubs. Prairie birds won’t nest in shrubby prairies. Many accounts of 1800s woodlands emphasize the ability to see deer far away and the fact that it was often possible to gallop a horse or drive a team and wagon through the woods.  

In our experience, efforts to plant shrubs have mostly not worked. Shrubs burned off with every fire, grew slowly, and failed to thrive.  

One exception, a trivial one in this context, is the experience with leadplant, prairie willow, and New Jersey tea in prairies. These are natural prairie species and do just fine even if burned off every year. 

A more meaningful exception is the experience with shrub thickets in wetlands or other areas that tend not to burn. Here, substantial populations of shrubby willows, wild plum, nannyberry, elderberry, prickly ash, dogwoods, and other species may do fairly well. A challenge for them is infestation by common or glossy buckthorn. These invasives may become dense enough to out-compete the native shrubs unless regularly cut back by stewards.  

Thus, for conservation, we may want to conserve shrubs in some places but not most.  

See also "Shrub Thickets of the Future: nature or gardening?" 

6. Should we use herbicide? 

Simple answer, yes, definitely. But be sure to read at least the last paragraph of this answer. Herbicide for an ailing ecosystem is comparable to medicine for a sick patient. No one defends misuse. Wise use can make a life-or-death difference.  

In the early days of restoration, many new stewards objected to herbicide on principle. The Nature Preserves badly needed stewards, so we advised people to the effect that “We recommend using herbicide on cut stumps. But if you want to experiment with working without it, give it a try. But do test your results and be in touch with others as we work through this.” In the end, every steward that tried the “no herbicide” approach either quit being a steward … or began to use herbicide.  

In very small areas, it could be possible to refrain from herbicide and just re-cut the brush re-sprouts over and over again. But the area restored would remain too small for most animal populations and probably most of the rest of the biota. If our goal is to save biodiversity, more time-efficient methods are needed. 

Reed canary grass has become an expanding bad pest in woodlands. No one has made progress against it by trying to pull it. There’s no practical alternative. The same is true for other species including crown vetch, purple loosestrife, and teasel. Herbicides are getting more sophisticated. A grass-specific herbicide can kill reed canary grass while maintaining the health of intermixed sedges, rushes, wildflowers, and the rest of the ecosystem.  

We’ve come to think of herbicide as an ecosystem medicine. Our ecosystems are degrading in ways that have parallels with human illnesses. Medicines used wrongly can harm and even kill the patient. That’s true of herbicides as well. They are helpful or even unequivocally needed in many cases, but they should be used with knowledge and care.  

7. Should we control deer?  

On most sites, yes. Over-populated white-tailed deer have badly degraded the ecosystem and even eliminated many species, of both plants and the animals that depend on those plants. Control is utterly crucial.  

Predation is an essential part of nature. For as long as these ecosystems have been here, deer numbers have been kept in balance mostly by mountain lions, wolves, and human hunters. If we have eliminated the first two of those, we must rely on the third.  

Deer control needs community support and therefore thoughtful outreach and education. 

8. What does it mean to employ holistic approaches?  

Respect the complexity and resilience of the ecosystem. 

We necessarily make ecosystem health decisions on the basis of very limited knowledge. Our therapies need to be good for the whole “patient” – meaning the overall biodiversity of animals, fungi, plants, soil biota, and all. (See also Endnote 3.) Of these, we need to be sure what we’re doing works for the rarest and most conservative components of the ecosystem.  

But shouldn’t we just work on the basis of the best science? More easily said than done.  

Barbara McClintock, not a bad scientist, won the Nobel Prize for her work on maize genetics. She describes plants as extraordinary “beyond our wildest expectations.” Not because they have found ways to do what humans can do but because a life lived rooted to one spot has coaxed then to evolve countless “ingenious mechanisms” to deal with challenges that animals might avoid by simply running away.” 

In achieving the revolutionary insights she came to, McClintock emphasized how important it was to acquire “a feeling for the organism,” to develop the patience to “hear what the material has to say to you.” In honoring her work, Merlin Sheldrake wrote: “When it comes to fungi, do we really have a chance? Mycelial lives are so other, their possibilities so strange. But perhaps they aren’t quite so remote as they seem at first glance. Many traditional cultures understand life to be an entangled whole. Today, the idea that all things are interconnected has been so well used that it has collapsed into a cliche.”

But it’s a cliché honored mostly in words. We have these suggestions for people trying to figure out woodland conservation: 

  • At one level plant diversity is the most practical indicator of site quality, but there are six to ten times as many fungi as plants. There are incomprehensibly many animals, bacteria, algae, and other micro-organisms, most poorly understood. Some seem to survive only in remnants. Entomologist Ron Panzer found that monitoring plants as indicators was insufficient to assess the health of most invertebrate populations. No one has researched these questions for most parts of biodiversity. Start with the best quality and biggest site you can, and trust it. 
  • Monitor as much as you can. Make decisions based on what’s best for biodiversity priorities overall, considering what data you can assemble. Realize that every action will benefit some species and impair others. The species groups most likely to benefit from the restoration of woodlands (of a few to a few hundred acres) are plants, invertebrates, and soil biota.
  • Is there any way to help soil biota? We hope that transplants from quality areas that are being destroyed may help. Rich woodlands are often destroyed for housing. When that happens, when we can, we transplant some of the more conservative plants to an “ecosystem re-assembly area” with hopes that bacteria, fungi, nematodes and other unknowns may respond well to the new, fire-maintained community. 
  • One person can’t manage, monitor, and make the decisions alone. Collaboration is needed. 
See also Endnote 4.  

9. What’s most important to success: Volunteer stewards or staff?  

Both, in collaboration, are essential for first class results. No site would have the resources it takes otherwise.  

We have watched and admired many agencies and individuals do good restoration without the kinds of collaboration we’ve enjoyed. Admired, yes; but our perception has been that results were not as rich and full as they could be with the benefit of a larger team. Staff do many things best: some kinds of planning, funding for “heavy lifting” work, land preservation in metro areas with good numbers of potential volunteers, empowerment of expert volunteers, and more. Citizen volunteers, on the other hand, frequently can accomplish more detailed work, of great complexity and delicacy, and often attain Phd-levels of expertise from the Eco-university of Hard Knocks, by spending years and decades focused on details a paid person would not possibly have time for among other responsibilities.  

Most of the work at Somme has been planned and done by volunteers. The hours that some people devote to sports, or the Internet, or the long list of other pursuits people spend “spare time” on – we can’t wait to spend with the ecosystem … being stewards. 

There are advantages in many differing approaches. But our experience is that an intensive professional-volunteer collaboration is an especially valuable one.  

For sample details about we authors as individuals, see Endnote 5.  


In the 1980s, there were good scientists who argued that open oak ecosystems were “Gone! Gone! Gone!” – and we should forget about them – because they can’t be restored. We now know that healing is possible. One key is to recognize that we cannot put anything back the way it was – or keep it that way – because nature evolves. That’s especially true as the world’s rainfall patterns, rain acidity, hydrology, climate, invasive species, fragmentation, and more are all changing mercilessly – and, to survive, ecosystems need to evolve. We seek to restore as much as possible self-regulating, changing natural communities with full animal, plant, and other diversity.  

Thriving communities can help mitigate climate change and provide ongoing resources for medicine, agriculture, industry, and research – to say nothing of the inspiration and beauty that almost everyone can appreciate.  

In our oak savannas and woodlands, our hard work allows us to experience something new on the planet – the recovery of badly wounded, incomprehensibly rich nature. We have the opportunity: to see real oak woodlands on fertile soil for the first time in a long time. Native Americans lived amongst and promoted such riches; Euro-American pioneers saw them and recognized them as prime farmland. But no ecologist ever – and no person of any kind for a couple of centuries – has had the experience. It’s like discovering a new continent. We can be part of an ecosystem previously unseen by ecologists and the modern world. It’s like archeology – if we could discover and restore an ancient civilization to life. But even that would be dull in comparison. Restore living remnants of great importance, beauty, and biodiversity? Yes, we can. 


Endnote 1.

Who are the experts on the conservation and restoration of woodlands? 

Volunteer and staff practitioners are making some of the fundamental discoveries. Are we the eco-counterpart of the Wright Brothers? That analogy was made compellingly by Bill Jordan (William R. Jordan III), founding editor of Ecological Restoration. Unlike the well-funded experts that Orville and Wilbur were competing with, the Brothers invented and discovered how to fly because they were immersed in the physical details of it. They made the parts, applied the grease, flew the prototypes, hammered, twisted, and shifted their body weight during flight until, bit by bit, it they figured it out. That analogy falls apart at the end. Their contraption could obviously fly, and the others could not. To demonstrate whether biodiversity conservation is working, we have a harder challenge. We have understand ecosystem function better than we currently do. And we have to know the alleles.  

Alleles are the basic building blocks of conservation. Most alleles can be lost long before a species goes extinct. In their millions of years of evolution, the animals and plants associated with oaks have developed the genetic riches that allow them to cope with competition, predation, fire, disease, climate, weather, and soils of various types. A rich woodland with full biodiversity has countless genes and alleles that could, in the future, be of huge benefit to people and the planet.  

We can imagine a distant time in which one form of agriculture would be little woodland gardens of Eden growing holistic polycultures of edible acorns, walnuts, hickory nuts, plums, apples, hazelnuts, blueberries, grapes, legumes, mushrooms, grains, spices, and medicines. But only if we conserve the alleles that could make it work. 

Our biodiversity heritage may include alleles that would help solve climate change, give rise to new medicines or better foods, and be the raw materials for scientific discoveries and economic benefits. To say nothing of beauty, art, ethics, and inspiration.  

To improve our answers to the questions discussed in this post, are there discoveries that unfunded volunteers and private landowners can make? Oh, yes there are. We without grant money may be in the best position to answer certain questions, because they require longer time periods than academics can typically invest … and because we can be more flexible in many ways, which may benefit this new field. 

Endnote 2. Fire research 

It’s essential. Short-term research won’t tell us what we need to know. Some parts of some sites might best have one consistent fire regime for at least five or ten years. Then that approach can be compared to others. Possible approaches for a site might include consistent a) early fall burns, b) late fall burns, c) spring burns, d) less intense burns, e) more intense burns, and f) various combinations of varied burns. For good science the key is to be consistent, keep good records, study the biota over substantial time periods, and publish results. Short of good research, the best approaches depend on observation, judgement, and a variety of approaches from site to site. 

Endnote 3. Recognizing the importance of Fungi to conservation 

Fungi are fundamentally important to plant communities, and little monitored on conservation lands.  

In the 1980s and 90s, we conservationists were initiating focused monitoring programs for rare plants, breeding birds, calling frogs, butterflies, dragonflies, and others. The Field Museum wisely proposed or agreed to sponsor a monitoring program for mushrooms. We learned to dry them for proper study and sent hundreds of specimens to the specialist who identified them. He reported that every site that submitted mushrooms included rare species – and that the rare ones were pretty much different from site to site. This should not surprise us. There are vastly more species of fungi than there are plants.  

There are no species of fungi recognized as endangered in Illinois. The federal endangered list includes fungi only in the form of two species of lichens. Globally, the IUCN lists just one fungus as endangered. The reason is lack of knowledge. We conservationists need to do better.  

Fungi, like animals and bacteria, are both crucially important to ecosystems and much more difficult than plants to monitor. Many mushrooms show their heads above ground to reproduce only briefly and only every few years. In between times, it’s hard to know what’s happening. Yet, they’re crucial to conserving whole, functioning ecosystems.  

Sadly, the Field Museum’s volunteer fungus monitoring lasted only until the staff responsible for the program left the museum, as professionals do. The monitoring then withered. It was too bad.  
In 2020, Merlin Sheldrake, 34 years old, published a world-significant book in a world-changing field: Entangled Life: how fungi make our worlds, change our minds, and shape our futures. Perhaps someone who reads it would take on the challenge of leading some conservation efforts on fungi in woodlands we work to restore? It’s needed, and it’s not happening. 

Ongoing research about the relationships among animal, plants, and fungi raise unsettling questions. Much that’s basic is not known. Life is more than we thought. As Sheldrake put it:  

“Fungi … make the world look different. … I have tried to find ways to enjoy the ambiguities that fungi present, but it’s not always easy to be comfortable in the space created by open questions. Agoraphobia can set in. It’s tempting to hide in small rooms built from quick answers.”  

We agree. We struggle to “leave questions open” while rescuing ecosystem patients from passing away. We believe in and try to have a “reverence for life” toward the diversity of nature. We have faith that future generations will better understand life on Earth, live within it richly and wisely.

Here's an example from Sheldrake, citing poorly-funded, bootstrappingly-carried-out research by Suzanne Simard and other pioneers in this new field. It compelling suggests how human culture and economy could better work with biodiversity:  

As part of the self-regulating complexity of a healthy system: a) fungus networks actively farm bacteria of general use to the ecosystem while, b) they pass chemical messages among trees, grasses, and wildflowers, c) alerting plants to an aphid attack on one plant so that, d) many connected plants release pheromones that attract the parasitic wasps that, e) reduce the populations of those aphids, benefiting all.  

It took millions of years to evolve such interconnections – which include alleles possibly of great value to the Earth’s future – supposing optimistically that our species someday develops a non-pathological relationship with the rest of life on this planet – even a symbiotic one? But for now, biodiversity survives tenuously. Do we really want to let it just slip away? To save ecosystem tottering on the brink, we can’t wait for all the research that would be helpful. We conservationists need to use judgment, make decisions, and do the best we can. 

The challenge and the adventure are hard to match. We find we make our best discoveries and do our best work when we recognize how much we don’t know, and strive for new understandings, while we make best use of what we do know.  

Endnote 4. Restraint vs. Initiative 

Some people believe that the best management is the least. Such beliefs are hypotheses that can be tested. Various management regimes should be monitored and compared. In some cases, for comparison, high-quality sites should be managed by fire and invasives control only. Biodiversity recovery and sustainability at such sites should be compared with more ambitiously managed sites. Current assertions about minimal care are more like religious doctrine than like science. 

There should not be a “one size fits all” approach to management for biodiversity conservation. We don’t know enough. And more importantly 1) sites are varied and 2) we can’t evaluate alternate methods unless we add up years of faithfully using one approach per site, measuring results, and comparing them with sites differently managed. 

Endnote 5: Who are the people writing this?  

Christos Economou, professionally, is a PhD research chemist looking for novel medicines to treat human diseases. After years of anguished reading about the global decline of biodiversity, a few years ago he was lucky enough to fall in with the North Branch Restoration Project’s Somme Woods team – and felt empowered that he might be able to do something about it. Now working on his “second PhD,” he spends a lot of his free time studying tallgrass nature, seeking out treatments for ecosystem diseases as a Somme Woods zone steward, and supporting newer stewards with Friends of Illinois Nature Preserves.

Matt Evans as a grad student studied historic oak distribution for Chicago Wilderness. Professionally, he is manager of McDonald Woods, a rich remnant at the Chicago Botanic Garden. He credits his collaborative work as a Somme zone steward with "at least as much" significant conservation and restoration learning as he benefitted from in academics. 

Eriko Kojima loved plants from her childhood in Yokohama and San Diego. After receiving a degree at the University of California and working as a landscape architect in Chicago, she was disappointed in what she could contribute and switched careers. Later, as a veteran Japanese-English conference interpreter, she discovered the ecosystem restoration mission and community at Somme. Since 2015, with the encouragement of husband and daughter, she has gradually cut back on her conference jobs to contribute as a volunteer steward and teacher at "more than full time" by professional standards.

Stephen Packard was Director of Science and Stewardship for the Illinois Nature Conservancy for 15 years and then did similar work directing Audubon Chicago Wilderness for 15 years. He considers it to have been a great privilege to work with and learn from many of the global experts on this stuff during that time, including expert volunteers. A great part of what he learned that informs this post was as a volunteer doing restoration in most of his “spare” time between 1977 and 2023. 

The writers of this post acknowledge the importance of discussions with and experiments by the zone stewards of the Somme preserves as explored in "field seminars" like the one shown above. 


The pathetic photo of spring flora that begins this post came from Horticulture Magazine. Does anyone want to contribute a better one? Woods with only spring ephemerals left are common - and superficially beautiful. 

A companion post in this blog that discusses the history and theory of oak ecosytems conservation.

Panzer, Ron et al. Prevalence of Remnant Dependence Among the Prairie- and Savanna-inhabiting Insects of the Chicago Region. Natural Areas Journal. 15(2),1995. 

Sheldrake, Merlin. Entangled Life: how fungi make our worlds, change our minds, and shape our futures. 2020 

Wilhelm, Gerould and Laura Rericha, Timberhill Savanna - Assessment of Landscape Management. April, 2007 

Attempted "Myth-Busting" - 

From Bill Kleiman and colleagues:


The drawings in this post are by Paul Nelson from Packard and Mutel's Tallgrass Restoration Handbook.


  1. Reed canary grass has shallow roots. It is easy to uproot with a tool. A small pitchfork and a half log for a fulcrum works well. More grows every year, so constant vigilance is needed. Herbicide is much easier. Is it better? I don’t know. If the minimum dose of herbicide is applied to only the reed canary grass, then adjacent plants that get impacted can recover (violets, bergamot). Although, I have not tested this on anything that is high-quality. It is easy to get a lot of people with pitch forks, but it is not easy to get lots of herbicide applicators.

    I’ve eliminated crown vetch by following the rhizomes through the soil and removing as many as I could find. It took me three years to get rid of crown vetch and bird’s-foot trefoil from a native plant garden this way. My park district won’t let volunteers apply herbicide. Herbicide is faster and does not churn up the soil. Herbicide is not without effects. Where glyphosate has been applied plants do not grow as well for a few years. I’ve seen crown vetch and bird’s-foot trefoil sprayed with Transline every year for over a decade. It kills them back to the ground for that season preventing seed formation. However, it has not gotten rid of them.

    Purple loosestrife gets big like a bush. The big ones are most easily treated with herbicide. If foaming glyphosate is applied to 6 inches of stem/leaves in spring or 4 inches of stem near the ground in fall this invasive can be controlled without killing adjacent plants. This is much better than the big dead zones created by spraying herbicides. For purple loosestrife that are a few stems or smaller it is just as easy to use a tool to uproot them as carefully apply foaming glyphosate. I removed a few hundred each evening. This was making good progress. Again, it is easy to get a lot of people to remove smaller purple loosestrife using a tool to extract them by the roots. Herbicide applicators are much fewer and far between.

    Finally, my old nemesis teasel. I just cut the stem at the base of the plant then cut off the seed heads in late summer. No need to harm all plants with herbicides.

    1. I worry that James' small-scale experiments will frustrate professionals and stewards with large areas to restore. But small scale techniques are very much needed in many cases. Important sites often have volunteer stewards and little other care. Many infestations start small. If they can be nipped in the bud by volunteers (with or without a ridiculously-time-consuming-to-get herbicide license), huge later damage and expense can be avoided. Often, the fundamental problem is not initially finding a small infestation of a dangerous malignant species. A volunteer who loves the site may be an especially good person to be on the watch.

    2. Small scale experiments are useful in order to verify a restoration technique. It can be, as pointed out, frustrating to determine an efficient and effective method to scale up the technique for large areas. Ingenuity or invention is needed. A case in point: over a 2-year period a 1-foot square of dense lily-of-the-valley (Convallaria majalis) was repeatedly hand clipped/snipped at ground level each spring. The density of the plants decreased each subsequent year, and no flowering/fruiting plants developed each fall. Scaling upward to address a multi-acre area infestation requires to use of a weed whip or similar tool, and a yearly commitment of at least five years is needed in order to reduce (or eliminate) the weed when eventually other techniques can be brought to bear in order to reach the goal of eradication.

      One objective of the original experiment (5 different tests) was to determine if a method other than herbiciding could be effective in eradicating the lilies.

    3. I should give more information. I did observe one damaged Culver’s root Veronicastrum virginicum (Coefficient of Conservatism 8) which recovered after being damaged the previous year from treating a small reed canary grass clump near it. I only treated reed canary grass in this area that were producing seed heads because of a lack of time. This had the effect of reducing total impact. I believe it is necessary to only treat a fraction of invasive species in a densely infested area each year if herbicide sensitive species are to recover.

      I should also mention using the above-described method of treating purple loosestrife in fall had much less impact on adjacent vegetation than when purple loosestrife was treated in the spring. The tall goldenrod and sawtooth sunflower in the spring application area (low quality) have recovered. By applying four percent foaming glyphosate to four inches of stem at the base of the plant in fall, I observed no damage to adjacent plants. I plan to apply herbicide in this manner again this fall to see if I can repeat this success.

  2. Some of the shrubs you list are not wetland species.

    Shrubs are important to woodlands. At Deer Grove Forest Preserve and Edward L. Ryerson Conservation Area there are a few mapleleaf viburnums. There are some hazelnuts at Deer Grove Forest Preserve. Fire will knock these shrubs back to the ground and may eliminate them with repeated burns. Wild plum is important in prairies. A good example of prairies with wild plum is Nachusa Grasslands. Shrub restoration would probably be most successful down wind of water features or the ‘head lands’ Dan Carter previously described where wind blows away the leaf litter fuel. If the ‘head lands’ were down wind of a water feature or north facing, then that would be best for mapleleaf viburnum.

    Fire controlling non-native invasive shrubs and mesic trees is also important. The most cost-effective approach would have to be removing fuel around native shrubs to protect the few that remain and burn everywhere else. Is this nature? No, but it is a reality with our native shrubs diminishing under the over-whelming number of invasive species.

    There is a problem with not getting intense enough fire to control gray dogwood in prairies or trees invading woodlands. The intensity of fire can be greatly increased with increased wind speed. Areas are already being burned in strips perpendicular to the wind for smoke loft. If strips were burned with the wind and the aid of leaf blowers to increase wind speed, then fire intensity could be increased where ecologists determined it was needed most. This would not be prohibitively expensive or unreasonably difficult while also not creating the risks of burning during extreme fire danger days. It is difficult to prevent a wildfire during extreme fire conditions but it is easy to turn off a few leaf blowers.

  3. Seems like you are describing thru your observations a hot topic on the SER conference scene known as "Adaptive Management" - a great method to aid in discovering success and failure in ecological restoration. Monitoring and novel observations are key, as is experimentation! Also, when discussing these plant communities it might be helpful to describe more the structure or species composition of various ecoregional variants. I've noticed that across the moisture and light gradients niche partitioning allows for one or the other species that is better adapted to that particular habitat. And when discussing woodland canopy structure we perhaps could reverse engineer the science of Forest ecology by thinking of how the prairie, savanna, and woodland became overgrown - terms like facilitated grown, secondary succession, canopy gap dynamics, etc can help us understand how the woodlands are now functioning more like a forest than an "oak openings" ecosystem. Overall though, I think restoration is leading towards bringing the open grassland and woodland communities together thru increased biodiversity for a more healthy, resilient, and stable ecosystem that can fluctuate over time with changing disturbance and other influences.

    1. Yes! Continuity between woods and prairies, their are so many biotic common denominators.

  4. A couple of quick comments from a rushed person. First, thank you. With respect to thinning and fire, consideration of ground layer as it relates to flammability is important. Where oak litter is the primary fuel (few sedges/grasses remain), any thinning should account for the importance of oak litter for all important annual/near annual fire. It's possible to initiate ground layer recovery before tree density or canopy goals are reached. For white oak woods, in particular, and especially on sand, caution is warrented where excessive fuels have accumulated. I think I've made that comment before, but I've seen several examples of mature white oak mortality from burns conducted where there was a lot of leaf litter was present and uphill headfire used. ...and just last week I had the pleasure of walking with Gary Birch in an area of woods he manages at Lake Kegonsa State Park. There, stewardship has been hampered by the cessation of the use of fire by WDNR at the site, but what potential! There is still Hypoxis.

    1. Dan Carter's thoughtful comments are always appreciated.

      I suspect Dan would agree that oak mortality is not always a negative. Many woodlands, after a century without fire, benefit from fewer trees. The benefit goes to many populations of conservative (conservation significant) plants and animals. And later to oak reproduction.

      More should be said and written about problems with misuse and lack of use of fire. Publicly owned conservation areas should have more active and plainspoken groups of citizen-scientists, appreciators, and advocates. Details of ongoing management should be more available to the interested public, on line for example. Many officials want all science that studies an agency's work to be under the agency's control. That's not the way to get the best science.

  5. Great observations, Steve.
    It all parallels 35 years of experience here on the Southern Illinois Tillplain ((Shoal Creek CA) Our soils, flora and fauna are distinctly different. But the management considerations are nearly identical.
    Results speak for themselves with some 750 species of plants and well over 70 species of butterflies and skippers. Sadly the numbers on the latter have plummeted. Pesticide drift also looms large as a major issue. But life goes on; every day is a blessing and worth getting up for. Henry

    1. Thanks, Henry. Few sites have 750 species of plants and 70 of butterflies. This work is urgent. People like you who have taken the initiate can make all the difference. Shoal Creek Barrens/Shoal Creek Conservation Area is a treasure, profoundly so.

  6. Thanks so much for this brilliant overview. The decades of passion and science is enlightening and sobering. Very appreciative to the authors for the patience to write and share the lessons learned in a easy to read format.

  7. We do need more fire research, but I'll put it out there--what are the best of the best places that aren't getting worse? In my experience every single one is getting fire on an average return of 1-2 years (woods or prairie), and every single one in the dormant season. So I guess I feel like the answer is obvious, but maybe others would be compelled by it. For the life of me I can't understand how people aren't compelled, but sites where the capacity or will to burn that often are too rare to register. I do have some questions about differences between fall and late winter/very early spring fire, but that seems quaint seeing how WDNR is still out there burning now and the attitude that if it'll burn it's a good time to burn seems to have won the day. ...but I must admit that I was buying into that 3 years ago.

    1. Yes, we have all gotten behind some “great” new idea and then tried it only to discover that it did not work the way we hoped. In land management this would include applying herbicide to one stem will kill multi-stem buckthorn (or any woody species for that matter), growing season burns, intense grazing …

      I must admit to feeling dumb that I do not know the answer when you wrote, “So I guess I feel like the answer is obvious, but maybe others would be compelled by it.” Could you explain further?

      You wrote, “What are the best of the best places that aren't getting worse?” The exponential growth of invasive species populations is difficult to manage. Fire is a tool that can stop the establishment of invasive woody species or kill them back to the ground to prevent them from reproducing but will not reverse the invasion once they have had a chance to establish. Large sites spot spray invasive species. I do not think this makes the sites better (a lot of good things are killed that do not return), but rather stops these sites from rapidly deteriorating. In other places, too little herbicide is applied. Woody invasive species become multi-stemmed sprouting stumps that take even longer to selectively treat. The result is often to foliar spraying sprouting stumps with the unavoidable damage to non-target plants.

      Applying herbicide in a selective manner is something only a few stewards who have extensive experience have been able to achieve. At these sites, improvement can be observed but the trade off is the labor-intensive methods only being performed correctly by a few people mean only small areas improve.

  8. Excellent discussion, as always. I agree with all points made. This conversation needs to spread to more agency/organization decision makers, restoration practitioners, and landowners. While we have a few model sites (and organizations) that embrace nearly all of the recommended approaches, they seem to be the exception rather than the rule. And, unfortunately, due to lack of resources (or understanding or motivation?) a lot of woodland "restoration" focuses primarily on brush removal and occasional infrequent fire and the resource continues to languish.