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Friday, September 16, 2016

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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


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

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

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

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

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

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

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

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

  

15 comments:

  1. Steve, you ask great questions and highlight the value of seeing old areas with new eyes. I wish more folks maintained long term monitoring stations that could contribute to a data bank of observations that could be used to answer many questions. Looking at what you present now, the difference in mowed vs unmowed portion is striking. My guess is gray goldenrod is a good survivor and competitor in dry, sunny possibly hot areas, hard to say it's preferences for nutrients as it grows with nitrogen fixers and also abused ag fields with some non-mycorrhizal plants. My recollection of other goldenrods is they can associate well with soil fungal networks that feed on decomposing woody roots. Over the years of strict prairie you lose the dead roots you cut decades earlier, at which point change may occur. But the mowing distinction is very telling. Gray goldenrod is short and I imagine it's seeds easily trapped and burned up when the grass is thick around it, not to mention light seed is pushed away from upward air or hot burned spots with high fuel, and eventually settle out downwind in areas where the wind is blocked, it is trapped by an obstacle like a tree, or temperature or wind subside due to topography or ground temperature. Might do well to pay attention to wafting seeds next prairie burn. It persists as a clone but seeding would not be expected to return to the same footprint.

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  2. Deb, you make good points. No doubt different processes are responsible for this species' presence in Grade A remnants vs. some restorations vs. old fields. In my experience, the seed is long dispersed by the time of the fires, and the seed (of many species at least) seems to know how to get down through the thatch and into the cool soil before at least the spring burns come through.

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    1. The thriving strip along the trail... is that a trail that is also used as a burn break? I know the track record of 1/2 every year holds pretty good for Somme Prairie Grove. Of course though right next to the brake the effects of the fire are a little different... the point where the fire spreads apart, more quickly flapped out, sometimes hosed down. How tight is the match between thriving and scythed area?

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    2. Deb, good questions. First, the trails in this case were not used for fire breaks, so that's not an issue. But the question of "how tight" is a good one. I'm going by my memory; the plots in this case were not marked on the ground - except "ecologically." That is, I scythed the tall goldenrod, and subsequently the scythed area "looked distinctly different." I could not tell you today exactly where the original boundaries were from memory. I actually have measurements in my files, but I haven't checked them. I'd like to. Thus, this experiment and my conclusions would be a lot more meaningful re-did the measurements and discussed the dates and numbers of the mowings. I hope to do more of that than I seem to have had time for in the past. I hope to do more.

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    3. I think it would be a good idea to gather up this and other observations, and field knowledge, that raises and partly answers questions for which more controlled experiments would be illuminating. Might make a great clearinghouse of ideas for grad students and researchers. I think Chicago Wilderness was best when it focused on encouraging that sort of feedback.

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  3. Great observations. I wonder about the role of betony, especially with respect to the grasses.
    Kent

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    1. Betony seems to be very effective in reducing tall grass cover - in some cases. In others, it seems not to take. This is something else that deserves experiment and study.

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    2. I wonder if these experiments could be done in folks' garden plots, with the right mix of species, and homeowners daily tending/observing. Weaver et al built underground frames, grew prairie plants in the soil insdie the deep frames with the plan to then dig them up, wash off the dirt and observe the root structure. beautiful photos came from that. Wish that book was still available.

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  4. I believe what you are observing is the biology of invasion. Intact ecosystems have an amazingly complex connectedness that results in diversity. Although numerous species are a component of an intact ecosystems, when isolated from those ecosystems these same species can completely dominate. It should be remembered that individual species with large coefficients of conservatism are not necessarily indications of successful restoration. It is the combination in an index like the FQI that truly measures ecosystem function. Some of the interactions that are needed to maintain diversity can be restored. An example is sowing seed of Pedicularis canadensis to reduce grass dominance. Another example is sowing Cuscuta glomerata to reduce dominance of certain members of the Aster or mint families. However, we must be honest in our inability to return the entire unfathomable diversity that constitutes an intact ecosystem. Only great amounts of time can do what has taken great amounts of time to create.

    I must wonder if the strategy of eliminating conservative plants that tend to dominate when beginning a restoration will prove to be a fruitless effort over time. It would seem more prudent to let these plants dominate until their day of glory has past and then establish weaker growing species that make a community diverse. However, no one should fault you for using your trusty scythe as a surrogate for what cannot be repaired. The substitute that is created through restoration efforts is better than what would result from doing nothing at all.

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  5. The use of the scythe in the one experiment caught my attention. Not just once but returning to be sure the grass remained short and subdued. This reminded me of something.

    Prior to the near extermination of the bison by the Europeans a similar disturbance occurred. The bison would seek out newly burned prairie to graze the tender young grass shoots as they emerged. During the course of the summer they would return again and again to nibble this tender grass and eat around the established forbs. Thus allowing light and warmth to the forbs they had avoided.

    The scything experiment suggest that this activity may have helped increase the diversity by allowing light and warmth down to the ground where seeds and young seedlings were beginning their life. As intended, plants that can't get started in the cool, dark places between grass, could now thrive free of the grass plant shade. This experiment mimicked a process long established in the prairie/ savanna ecosystem. The process of bison grazing.

    Will the bison grazing plains at Nachusa explode with diversity in the next few years in part from this simple disturbance?

    Should we look at mimicking this natural disturbance by the bison with more use of the scythe?

    Can one use a scythe with the precision bison eat around forbs?

    It might be good to add this tool to our restoration toolbox and see if we can repeat some of the success in increasing diversity that Stephen observed.

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    1. Yes, well put. The scythe "may have helped increase the diversity by allowing light and warmth down to the ground where the seeds and young seedlings were beginning their life."

      Yes, scythes can be very selective. With a slender, very sharp, long-pointed scythe, a practiced person can cut the tall grasses at the base while leaving the orchids, gentians and all else standing, even less than an inch away.

      There is much more to be learned about the good and bad of bison management on prairie remnants. I'm researching that for another blog post. All factual input appreciated - from anyone who has it.

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    2. The grazing issue is complicated and one that I want to let Stephen present before discussing.

      However, haying appears to be much less controversial. A number of preserves containing very rare species were used for haying.

      "In Europe, biologists are finding that multiple decades of annual haying can actually improve plant diversity by reducing nitrogen levels that favor a few dominant plants"

      "The Ecology and Management of Prairies in the Central United States", pp. 92, Chris Helzer

      Mr. Helzer follows the above quote by talking about the disadvantages of haying. One problem mentioned is haying is non-selective. This is not a concern that applies to Stephen's method. The only potential problem I can imagine is woody species might colonize in certain situations if haying is used to weaken dominating grasses.

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    3. Woody plants would get chopped up in the haying. I have a feeling that Spring Lake Nature Preserve was hayed for 'marsh grass.' Beautiful soil, what Liam when he visited it referred to as Olde soil, very rich in aggregates, and the small sedges and wildflowers of spring are beautiful, and the small wildflowers of autumn are beautiful, and the wind-blown seeds of summer plants are abundant and beautiful.... but a lot of species are missing, probably cut down over the years from the farmer's hay mower. No native legumes to speak of. No blazing star (mostly). No rattlesnake master. No flowering spurge. No coneflower. So I think bison would be better than mowing. Excellent sweetgrass, dropseed, sedges and grasses, marsh betony, joe pye, mountain mint, indian plantain, yellow-star grass, used to be tons of gentians.

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    4. I acknowledge that repeated haying could cause the loss of certain species. This is the reason I mentioned Mr. Helzer, in his book, discusses some disadvantages of haying including that it is non-selective. In contrast, the scything of taller grasses and weedy species that Stephen does is selective and should not cause a loss of desired species.

      Although woody plants do get cut back to the ground from cutting, most of them (accept juniper) resprout vigorously.

      “Mowing can also increase woody plants three to one.”

      “Restoring the Tallgrass Prairie: An Illustrated Manual for Iowa and the Upper Midwest”, pp. 52, Shirley Shirley

      Ms. Shirley was comparing using mowing for prairie management compared to burning.

      Indeed, haying or scything during the growing season will weaken the existing vegetation much more than dormant season mowing. Weakening the vegetation will benefit species that are trying to get established. This is good if the species that are benefited are orchids and gentians, but not so good if undesired woody species increase.

      This discussion is not a thought experiment. I have personally observed the above in my sedge meadow garden. In areas where I “selectively graze”, to quote Mr. Helzer, the orchids I have planted grow better. In fact, I think if I did not cut the sedges back once each year the orchids would disappear from my garden. This is the kind of difficulty that often occurs when trying to grow a species away from its natural ecosystem. In contrast, other species that I do not want to increase also take advantage of the weakened state of the sedges and must be removed. It is not only cutting, but also trampling by wildlife that creates areas where the sedges are weakened in my garden. There are an especially large amount of Hibiscus moscheutos seedlings emerging in the areas impacted by cutting or trampling.

      A good place to observe actually woody species taking advantage of weakened grasses is in lawns that are mowed but do not have herbicide applied. These lawns are full of bonsaied woody species just waiting for their chance to grow tall and shade out the grasses.

      Fire can reduce woody species, but once woody species get established even annual fires do not always eliminate them. Therefore, care must be taken when reducing the vigor of existing vegetation to make sure the ecosystem moves in the direction you want and not away from it.

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