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Thursday, November 2, 2023

Comments From Dennis Nyberg on Health of Nature Preserves

Comments by Dr. Dennis Nyberg, professor and natural areas researcher, University of Illinois Chicago, retired, and perhaps equally importantly, for decades the steward of Cranberry Slough Nature Preserve, and for 15 years steward of UIC's prairie in Glenview, IL.

These good thoughts are a response to a recent post on the degradation of Morton Grove Nature Preserve.

Ownership: Nature Preserves in Illinois have a diverse array of owners including the Illinois Department of Natural Resources, County Forest Preserves, School Districts and other government agencies, Universities, Land Trusts, private individuals, etc. It is important for the Nature Preserves Commission staff to work with each owner to assure ongoing understanding of the importance of management and to assist the agency in accomplishing it.


Needs: There are many who still think land acquisition is as important as it once was. Acquisition is rarely a top priority now. Restoration and management are crucial.


Management needs are complex and diverse, but just repeated fire (simple management) would do a lot for most preserves. Superficial monitoring is a minor need. Most people trained as botanists seem to be most interested in rarity. The people I know who have been the most effective conservationists tend not to be trained botanists, but they have an affection for nature, and they learn.


Many botanists are observers (tourists). They focus on keeping records. Such people do not typically know about how to manage populations. So I don’t see more inventories and monitoring as the best way to spend money. (The original Illinois Natural Areas Inventory focused best on prairies. It did not do a good job of identifying natural oak woodlands.)


When Bill Glass was responsible for Iroquois County State Wildlife Area, it got burned regularly, and I thought it was the best natural area in IL, now other sites are where I take students. Revis Hill Prairie Nature Preserve is another site that’s suffered from lack of needed fire.


NICHES Land Trust has done at least two things I think are wise. First, they no longer accept a donation of land without a contribution to their Stewardship Fund which provides money to manage the  donated land. Second, they get volunteer help, including but not exclusively vegetation management, in exchange for white-tailed deer hunting privileges (accomplishing 2 goals at once). The focus of Nature Preserves ought to be on preserving the species of the area rather than forbidding leaving trails, collecting small plant parts for personal use, fishing etc. We need more people out enjoying and using nature. That is how they come to love it.


Trees grow. In 1900 trees were harvested for many purposes. Preventing further harvest on conservation land was important at that time. Now there are bigger trees with shade and water usage that prevent the understory and its insects from flourishing. Conservation people need to support removal of large trees when fire hasn’t been sufficient to keep the canopy open enough for most original plant and animal species.


I believe there needs to be more emphasis on the species that a nature preserve is protecting. Priority species have to have a population (greater than a dozen individuals) with recruitment (or potential for recruitment) and have a greater population at that preserve than other preserves. Populations can be measured concretely; communities cannot. I have maintained an interest in Cranberry Slough nature preserve though I no longer have an official role. I have a list of 17 plants species that CSNP plays a special role in maintaining regionally, i.e. have populations at Cranberry that are bigger than other regional sites that I have visited. If each preserve had a list of such species, it would direct attention to management and provide a measure of management success.


Tomlinson Nature Preserve (Champaign Co FP) does have too many hazel, and they are suppressing herbaceous vegetation. The only special species at Tomlinson (I only visited twice in last couple years) is another woody, Celastrus scandens, the native bittersweet which I heard is being considered for state listing. I am guessing the bittersweet preservation will make hazel reduction more difficult. There were only a few hazel plants at Cranberry and prescribed burning killed all, but when I visited Cedar Creek (in MN) the plot that had been burnt most frequently, 17 times in 30 years, had an understory dominated by hazel. Not easy to make generalizations in vegetation management.


When I was in 8th grade the garden club of Northbrook sent me to Springfield for conservation training by IDNR. That training promoted the use of multiflora rose (in hedgerows to promote pheasant populations). I am aware that the Soil Conservation Service brought in and promoted use of kudzu and other invasive species. There was little interest in managing natural areas at that time. Today there is an interest in managing conservation lands to preserve native species. Almost all work involves the use of herbicides. I have seen good and bad results from herbicide use. I have an affection for the ways of non-economic people (e.g. indigenous) and consider the economy as the main source of loss of native plants. I believe in 50 years some of the current use of herbicide by conservation agencies will be looked on as we currently look at multiflora rose.


At Rocky Glen in Peoria there is savanna on the steep ridges. Rocky Glen impressed me as a once nice site that is dying. Many native species are hanging on (the species list would look impressive), but very few desirable natives are producing seed. Some individual plants can live 100 years, but if they are not producing seed that successfully recruits young individuals the species will disappear. I was encouraged to give my opinions to the manager, but I did not as I concluded he would not be responsive to unsolicited advice,


Good luck persuading people to pay attention to nature and making sure it persists into the future. The fact that the state of Illinois is no longer in financial straits offers hope.


Dennis W Nyberg

31 Oct 2023


  1. I’m curious how herbicides are being used that’s causing you concern.

    1. Herbicides are being sprayed on invasive brush (especially) and the spraying often causes considerable 'collateral damage'. One place this is still evident if on the east side of Country Lane just south of 87th ST. The entire slope is still almost to bare of living plants 2 years after herbiciding of honeysuckle. No conservative natives survived. I suspect the individuals employed by contractors empty their heavy backbacks with little attention to non-target species. Many individuals think killing invasive species is their job rather than the recovery of native vegetation thru killing invasive species. Such individuals are heavy users of herbicide. I see the problem as biological and look for solutions within the technology of indigenous people rather than the solutions advocated by the chemical industry.

    2. "Many individuals think killing invasive species is their job rather than the recovery of native vegetation thru the killing of invasive species." Here here! Various programs too. The game is promoting the coming together or healing of natural communities, and that requires minimizing chaos and maximizing stability. Careless herbicide use is chaos. Judicious and targeted use can be towards fostering a more stable site condition that meets the requirements of the species that comprise the community being restored or reconstructed.

    3. The following post I wrote shows the results after foliar spraying invasive woody species in an invaded savanna. I start with the good, the stewards treating cut stumps in winter, and then discuss several issues I see with management further into the post. The area where invasive woody species were sprayed is now full of common mullein. The stewards said they were spreading seed of shooting star this past spring where the invasive woody species were sprayed on this slope. I wrote to tell them they would be better off saving the seed for a better area. I don't know if they proceeded with the original plan or chose a better spot with native cover (rather than just weeds).

  2. thank you Dr. Nyberg for putting many thoughts so clearly and succinctly!

  3. I do not enjoy mentioning the following. However, I do think it is an important topic.

    The book Mr. Packard co-edited, "The Tallgrass Restoration Handbook: For Prairies, Savannas, and Woodlands" has a chapter on "Controlling Invasive Plants." In this chapter, it is suggested that foliar spraying be used in "High-Quality Natural Areas, Restorations, and Degraded Areas" for controlling several listed invasive herbaceous species. For "Restorations and Degraded Areas," foliar spraying is suggested for most invasive species listed.

    Spraying causes a lot of off-target damage often setting the ecosystem back to weedy annual species. There are methods that can prevent this from occurring. For example, I have been applying glyphosate foam by gloved hands with both good control of herbaceous invasive species and good recovery of native plants. However, I am beginning to think the method used by Laura Hunt of the Southeastern Grasslands Initiative of dispensing herbicide foam directly onto leaves and stems will be what applicators chose as the best available method going forward when application of herbicide to foliage is the only viable option (crown vetch). In Ms. Hunt's method, herbicide is not gotten on gloves but is dispensed directly on the plant covering about 1/3 of stems and leaves. I think this method will give the best balance between effectiveness, selectivity, and applicator comfort.

    The foam has the advantage over spraying in that it does not form droplets but rather comes out of the dispenser in globs that stick to the leaves/stems while it dries. This prevents over spray and reduces the chance of dripping off the target plant. My experience leads me to believe herbicide foam is a 'game changer' for selective control of herbaceous species.

    1. Applying foam should result in much less collateral damage than applying herbicide via aerial droplet i.e., spraying. The care of the individuals doing the work, I believe, is more influential on outcome than the application method. Care does translate into developing better application methods such as those you describe.

    2. The labels for commonly used herbicides stress full & uniform leaf coverage & don’t mention foam. Any deviation from the label increases the possibility of inconsistent results. Even with good coverage, it’s often necessary to add an adjuvant to ensure leaf penetration under all the variables encountered like drought stress, season of application, growth stage, etc. Foam will get less herbicide into the plant for both cut stump & foliar application, plus foliar leaf coverage will be patchy, as shown in the vendor’s videos. The vendor tries to compensate for this with glyphosate by recommending ~4% active ingredient, way more than normal. But they don’t recommend concentrations for other herbicides. For cut stump, they use the standard 20% ai glyphosate, probably no higher because they say foaming decreases as you increase concentration beyond that point. So foam will get less ai into the stump compared to spray or drip. For crown vetch in particular, I’m skeptical that foam application is effective beyond top killing, because controlling that plant underground requires good leaf & stem coverage above ground.

    3. Laura Hunt swears by herbicide foam. You can ask her yourself. She is the volunteer coordinator for the Southeastern Grasslands Institute. She did plots and now uses herbicide foam regularly with volunteers.

      Ms. Hunt mentioned the concentration does have to be higher when applying herbicide foam than spraying. That does not necessarily mean more herbicide is used. The manufacturer suggests covering only about 10 to 20 percent of foliage when hard to kill knotweed is controlled with a foliar application. Ms. Hunt covers about 30 percent of Lespedeza sericea with herbicide foam using a triclopyr herbicide.

    4. Repeating myself, when I have completely covered crown vetch with about four percent a.i. glyphosate foam (or above) using gloved hands the crown vetch does not come back the following year. I did my initial trial on July 21, which I later learned is about the worst possible time to treat crown vetch with herbicide.

      This year, I did trials to determine if I can apply higher concentrations of glyphosate to four inches of stem at the base of plants to get a high-level of control while spending less time applying herbicide and reducing off-target damage. I made each plot rather larger, about 25 square feet, so it took me an hour to apply glyphosate foam to every crown vetch stem in a plot.

      It was so much effort, that I broke the applications up into different days. The applications ranged from the end of July to September. The period between applying herbicide to each plot occurred over such a long period because I was busy with purple loosestrife and teasel control too. I started with the highest concentration of herbicide, eight percent then seven percent and finally six percent a.i. glyphosate foam. I will not have the final results until next spring/early summer. However, the plot that already has crown vetch sprouting from the ground was the one I did at the end of July with the highest concentration of herbicide (eight percent a.i.). This makes it rather apparent that the date when the herbicide is applied is very important. I had read before that the date of herbicide application was important for other species (Phragmites), but until this trial I had never seen the difference so obviously apparent.

    5. The link below shows a plot invaded by crown vetch (before the application) and a plot several weeks after the crown vetch had herbicide applied.

      To compensate for changes in effectiveness depending on when the application occurs, I am considering treating many smaller plots throughout a growing season so I can make a contour plot of application effectiveness of different glyphosate foam concentrations dependent upon when the application occurs.

      I think a grad student should be doing this work and the results should be given to volunteers. Yet here I am trying to figure it all out by myself.

    6. Stewards cannot carefully apply herbicide to everything that needs to be treated with herbicide in fall, collect seeds, and do everything else. This is the reason a chart giving effectiveness for varying concentrations through the growing season is needed.

    7. I could not have done as good of a job controlling the crown vetch and not impacting the spiderwort if I had applied the glyphosate foam to each crown vetch stem with a gloved hand. I don’t completely understand how spraying the plant with globs of glyphosate foam caused less off-target damage than carefully applying the glyphosate foam over the entire plant with gloved hands. When I used a gloved hand to completely cover the foliage of crown vetch or purple loosestrife with four percent glyphosate foam typically there is SOME damage visible, even though the non-target plants have been observed to fully recover next year.

    8. The link below has a blog post I wrote showing the crown vetch about a month after having been sprayed with gobs of glyphosate foam looking nice and dead (for now) and the spiderworts that was growing under the mass of crown vetch looking completely unimpacted.

    9. John Lampe did a talk at the last Wild Things Conference quoting studies that might explain the results visible in the above link. If my memory is correct some of the titles of these studies were roughly, "For the same amount of herbicide applied a higher effectiveness is achieved when a higher concentration of herbicide is used"; "Applying herbicide to veins of a plant better transports herbicide to roots"; "Foam dries more slowly increasing humidity keeping stomata open for longer leading to better absorption"; etc.

      My next step will be to applying the glyphosate foam directly along stems of the compound leaves of crown vetch mixed with prairie plants to see if I can kill the crown vetch without harming prairie species. If this much easier application method does not work better in real prairie, I can always continue applying four percent active ingredient glyphosate foam with gloved hands covering the entire plant, which I have been successfully using for the past few years.

  4. To clarify my post, all new ideas have costs/benefits & before those ideas are widely replicated in practice, the costs are usually unknown. A big challenge in restoration is variable effectiveness of techniques from site to site & while we have theories as to why that is, there is much we need to learn. So I was trying to point out things to watch out for when experimenting with foam. For me, there is nothing more frustrating than spending an unpaid field season using a technique I subsequently learn is only partially effective.

    Thank you for your willingness to experiment. Not many of us have the time to do it. Your observation that late July application to crown vetch was the least effective is valuable.

    Crafting an accurate test is very difficult (e.g. Kleiman’s blog on publishing his experiment) & I struggle with it even though it was part of my job for decades. So I hope you don’t mind some suggestions. Effectiveness of herbicides on clonal plants like crown vetch should be measured on an entire, isolated patch. Typically a single treatment on a portion of the patch will kill the rhizome only in the vicinity of the treated area. So the goal is which treatment kills as much of the rhizome as possible to minimize revisits. It can take 4 or more years to eradicate a large CV patch with your best people using the best techniques. Smaller, young patches are easier to kill than larger, older ones so select a patch size typical of the ones you want to treat & report patch size in the results so the reader knows if it applies to their situation or not.

    For those trying out foam with triclopyr or other herbicides more mobile in the soil than glyphosate, keep in mind that if foam does hit the ground, it will likely be a much higher concentration than the label allows, which could cause unintended environmental effects.

  5. “For me, there is nothing more frustrating than spending an unpaid field season using a technique I subsequently learn is only partially effective.”

    -I do not try for 100 percent control on the first pass, but rather target 95 percent control. If I get 100 percent control on the first pass, I know I could be using less herbicide. However, I know what you mean.

    -I’ve watched people spray large established patches of crown vetch with Transline every year for over a decade. Each year the crown vetch is back in the same spot. Maybe the concentration they used is too low. Maybe they have just been spraying at the wrong time in the season.

    -I’ve helped cut invasive woody species over many years, watched others apply the herbicide, then returned the next growing season to see all the cut invasive woody species sprouting from the ground more densely. Maybe the problem is cutting and applying the herbicide too late into winter.

    -We just can’t afford to be wasting decades of work and getting nowhere.

    “Effectiveness of herbicides on clonal plants like crown vetch should be measured on an entire, isolated patch. Typically a single treatment on a portion of the patch will kill the rhizome only in the vicinity of the treated area.”

    -Yes, I am aware. When I sprayed globs of glyphosate foam onto patches of crown vetch I did not spray areas where the crown vetch was intermixed with native grasses I wanted to save. Some crown vetch is visible in the background of the previously mentioned blog post “Selectivity of Glyphosate Foam.” I plan on returning and carefully applying the glyphosate foam to individual crown vetch leaves later avoiding getting the herbicide on the native grasses. One step at a time.

    1. I agree that herbicide applications should be followed up & failures investigated. My 8/24/23 post on this blog has a list of root causes for failures I’ve seen. The most common ones for crown vetch are spraying at the wrong growth stage, not using an adjuvant for better leaf penetration, spraying part of a clone instead of the whole thing & not coating as much of the leaves & stems as possible. Especially the last one since CV is a tangled mess. For the case you mentioned, I recommend Milestone over Transline for the reasons given in my blog post. The most common failures I’ve seen for cut stump are not applying enough herbicide (e.g. wick or sponge), not spraying immediately after cutting (for glyphosate) & cutting too far above the ground. I’ve used both glyphosate & triclopyr/oil in all seasons for cut stump & always had good results on all the usual species but that is just one person’s experience. Precip too soon after spraying may also be a leading factor for any herbicide application. Labels are vague about that.

    2. Yes, all those could be reasons I have seen failures over the years. I can visit sites to see what various people are doing. This has been a good way to learn ways to improve. However, if I see someone failing and I know the reason, I cannot make them listen to the advice you give. People do what they want to do.