Counting Gayfeather Stems Out Of Scientific Curiosity – Year 2

Science doesn’t have to be complicated or difficult.  In fact, the essence of science is really just a way to satisfy our curiosity about the world.

There is great value in rigorous science, with sufficient replication and statistical power to merit publication in peer-reviewed journals.  That kind of science moves us forward as a scientific community, and provides checks and balances to make sure we don’t go too far down the wrong path.  At the other end of the spectrum, however, is the kind of science that any naturalist or land manager can use to answer basic questions about how the world works.  An observation triggers a question, and more observations help answer that question.

I photographed this dotted gayfeather at our family prairie the other night. When I noticed it flowering, I knew it was time to revisit my project from last year.

Exactly one year ago, I posted the results of about a half hour’s worth of data collection on dotted gayfeather (Liatris punctata) plants.  I had noticed that plants in one part of one of our restored Platte River Prairies seemed to have a lot more flowering stems than in another part of the same prairie.  It was pretty easy to walk around and count enough stems in both patches and see if my observation could be confirmed by data.  It was.  Gayfeather plants growing in the half that had been burned and grazed intensively during the previous year had many more flowering stems than those growing in the half that hadn’t been burned and was only lightly grazed.

This photo was taken back in 2017, and shows a huge dotted gayfeather plant in an area where the previous year’s burning/grazing had reduced grass competition.  You can also see an abundance of yarrow and stiff goldenrod that seemed to respond positively to the less competition.

At the time, I speculated that perhaps the reduced competition from grazed/stressed grasses had allowed the dotted gayfeather plants an opportunity to produce a lot more flowering stems.  You can read last year’s post for more details on my hypothesis, if you like, but in that post I’d promised to revisit the site again in future years to see if patterns of stem abundance fit my guess.

Well, I kept my promise yesterday, and the results are very interesting!

The number of stems per plant in the east half of the prairie didn’t really change between 2017 and 2018.  That half was has been largely ungrazed for the last couple years but was burned this spring and is currently being grazed pretty intensively.  The west half is where I noticed many more stems per plant in 2017 (the year after it was burned and grazed).  However, in 2018, the number of stems/plant in the west half came way down to match that in the east.  My initial hypothesis is supported!  (The error bars here represent 95% confidence intervals, for those of you who care about that sort of thing.)

The above graph shows averages based on counts of 58 and 63 plants from the east half of the prairie in 2017 and 2018, respectively.  In the west half, I counted 53 plants in 2017 and 43 in 2018 – it was harder to find flowering plants in 2018, making me wonder if some didn’t bloom or if they were just hidden in the dense grass (or both).

The west half of the prairie, was burned/grazed in 2016 and had very high numbers of  gayfeather stems/plant in 2017.  It was completely rested from grazing last year and is only getting very light grazing pressure in 2018.  As a result, grasses have recovered very well, and now grow pretty thickly around the dotted gayfeather plants.  My prediction was that as grasses recovered, the number of gayfeather stems would decrease.  They did.  In 2017, I was finding a lot of plants with stem numbers in the 20’s and 30’s, and one gigantic plant had 51 stems!  In the same area a year later, I found one plant with 21 stems and all the rest had 10 or fewer (most had 3 or fewer).

In the west half of the prairie, grasses have recovered after two years of near complete rest, and dotted gayfeather plants now have a lot more competition for light and space.  Most plants had only a few flowering stems, and based on how hard I had to look to find them, I wonder if many didn’t even flower this year.

Meanwhile, the east half was burned this spring and has been getting pretty intensive grazing all season long.  Cattle have been mainly focusing on grasses like big bluestem and Indiangrass.  It’s pretty similar to the way the west half was grazed in 2016, though this year’s high rainfall has let some grasses grow faster than the cattle can eat them.  As a result, the overall grazing intensity – and the stress on grass plants – won’t be quite as strong as it was when the west half was grazed in 2016, but I’m hoping it will be enough that grasses will be much less competitive in 2019.  If so, and if my hypothesis is right, I should see gayfeather stem numbers go way up in 2019 in this area.

In the east half of the prairie, this year’s burn has led cattle to graze grasses fairly intensively.  Those grasses should be much less competitive next year, and I expect to see gayfeather plants produce a lot more stems per plant.  We’ll see if I’m right in about a year.

So far, I’ve invested about 2 hours worth of time on this project.  That includes about 30 minutes of data collection each year (walking around and counting stems on all the plants I encountered) and about the same amount of time entering the data and creating a graph.  Despite that, I’m gaining confidence that my initial hypothesis about grass competition and gayfeather stem numbers was on the right track.  A year from now, if gayfeather stem numbers increase dramatically in the east half (burned and grazed this year) and stay about the same in the west, I’ll be pretty confident in my answer.

Now, my results aren’t going to cure cancer or likely change the world in any measurable way.  I probably won’t submit my results to a peer-reviewed journal (although I might actually submit a “note” if the results warrant it).  On the other hand, I’m learning a lot, and what I’m observing is a small clue to a larger puzzle.  I’ve got years of much more rigorous data showing that short-lived wildflowers respond very positively after grazing reduces the vigor of competing grasses.  That wildflower response, however, has mostly been from the germination of new plants that fill in while grasses are weak and then die out again as grasses retake their previous territory.

My observations of dotted gayfeather are giving me some intriguing insight into how long-lived perennial plants might respond to the same reduction of grass competition.  It appears likely that at least some long-lived plants are able to take advantage of that lighter competition by producing many more stems, leaves, and flowers.  That increase must certainly benefit pollinators, and maybe other organisms that feed on gayfeather.  Is it also important to the long-term survival of the plants?  Good question!  The plants sure create a lot more seeds when they make more flowers.  It would be really interesting to know if the plants also produce a bonanza of new buds at their bases (those buds are what allow them to grow new stems in the future).

Regardless of whether more flowering stems has long-term benefits of the plant itself, the phenomenon sure provides an abundance of resources for bees, butterflies, and other pollinators.

Remember – this whole story started because I happened to notice a lot of flowers in one part of our prairies and took 30 minutes to count them.  That kind of cyclical curiosity and observation is the foundation of science, and is the reason we’ve learned what we have about the world around us.  Who knows – maybe my little gayfeather project will lead others to build upon my observations with a more rigorous project that will lead to greater understanding of plant communities, competition, and response to grazing and other stresses.  Whether it does or not, I’m already getting what I wanted out of the project – I’m having fun, learning something new, and stimulating my brain to come up with more questions about the prairies I love.

What are you seeing?  What kinds of questions are tickling your brain as a result?  Do you have a spare hour or two to explore a little further?  Think of what all of us could be learning with just a little bit of time and effort!

Does Dotted Gayfeather Flower More Under Reduced Competition?

Late summer is definitely a season of yellow flowers in prairies, with goldenrods and sunflowers in the vanguard.  However, there are exceptions to the yellow rule, and one of the most prominent of those in our prairies right now is dotted gayfeather (Liatris punctata).

Dotted gayfeather punctuated an otherwise yellow-dominated plant community last week at our family prairie south of Aurora, Nebraska.

Last week, I was collecting data on the number of flowering stems within various management treatments at our Platte River Prairies, and noticed an apparent pattern with dotted gayfeather.  In particular, I thought I was seeing more flowering stems on gayfeather plants in one treatment than another right next to it.  I had a little extra time, so I tested the observation by counting the stems on a bunch of plants in each treatment, and sure enough – I was right.  Where we had burned and intensively grazed the prairie last year, there were more than twice as many flowering stems per plant (on average) as there were in the unburned, lightly grazed patch right next to it.  Both areas were in the same restored prairie (planted in 2000).  You might recall a post I wrote back in mid-August about this same site, which included photos of both the 2016 burn and unburned areas…

Error bars represent 95% confidence intervals

I collected my dotted gayfeather data pretty simply – I just walked through each part of the prairie and counted the ramets (stems) of every plant I encountered.  In total, I counted stems on 58 plants in the unburned patch and 53 plants in the 2016 burn.  The average number of stems per plant in the unburned/lightly grazed patch was 6.12, compared to 12.5 in the burned/grazed patch.  A big majority (76%) of the plants in the unburned area had 10 or fewer stems per plant, and the highest number of stems on any plant was 17.  By comparison, only 56% of the plants in the 2016 burn patch had 10 or fewer stems and eleven plants (21%) had more than 17 stems.  There were some extraordinarily large plants in the 2016 burn patch, including plants with 39, 40, 42, and even 51 stems!

One of the larger plants in the 2016 burn patch

Now, this is a single site and it’s really important not to draw too many conclusions from a one year sample.  I’ll be looking at the same site again over the next couple years to see how things change as future management is applied differently to each patch.  The unburned area is slated to be burned and grazed in 2018, for example, so it will be really interesting to see how dotted gayfeather plants look in both 2018 and 2019.  I’m not sharing my data from this year because I think there are conclusions to be drawn from it, but rather because it’s fun to speculate about what might have caused the apparent pattern.  I’m hoping some of you will enjoy speculating with me, and maybe even look around in prairies near you for similar patterns.

In that spirit, here are a few thoughts running through my head.  First of all, the 2016 burn patch in this restored prairie was grazed really intensively all of last season, which severely weakened the vigor of dominant grasses.  Coming into this season, most of those grasses were very short in stature, allowing a lot of light to hit the ground, and their root systems were greatly reduced, allowing space for a flush of opportunistic plants to flourish – including dandelions (Taraxacum officinale), yarrow (Achillea millefolium), hoary vervain (Verbena stricta), stiff goldenrod (Solidago rigida) and many others.  However, we also saw abundant seedlings of long-lived, more conservative plants as well, especially white and purple prairie clover (Dalea sp).

Many of the opportunistic plants that flourish in times of abundant light and root space do so through establishment of new plants from seeds waiting in the soil.  However, that’s not the only way plants can respond.   Most perennial plants, including dotted gayfeather, grow new stems each year from buds that are produced at the base of the plant or on rhizomes (underground stems).  Each bud represents a potential future flowering stem, and healthy plants can have quite a few of those buds and deploy them as needed.

Here is the 2016 burn patch about a year ago, after a spring burn and season-long intensive grazing. You can see ungrazed dotted gayfeather flowers blooming. but most grass leaves have been grazed short.

It makes sense to me that dotted gayfeather plants in our 2016 burn patch deployed more buds this spring than plants in the nearby unburned patch where surrounding vegetation is more dense.  Long-lived plants like dotted gayfeather should benefit from producing extra flowers/seeds in years when their competition is weakened.  Maybe abundant bud deployment happened because gayfeather plants were able to expand their root systems last year and reach new resources, or maybe the short stature of surrounding vegetation allowed more light to hit the base of the plant this spring, triggering buds to open.

Of course it’s also possible that all my speculation is complete bunk.  Maybe the plants in the 2016 burn patch are always bigger than those to the east, regardless of management, and I just hadn’t noticed before.  If so, I’ll know that after a couple more years of sampling.  Either way, it’s sure fun to wonder what might be happening and then collect data to test whether or not I’m right.  Opportunities like that are exactly why I love being a scientist.

Please share your thoughts and experiences related to this topic, and if you get a chance to go look at dotted gayfeather plants in patch-burned grazed prairie or other similar situations, let me know what you see!

Photo of the Week – November 26, 2015

The sky yesterday was mostly overcast and dark, but I looked out my window mid morning and noticed the clouds thinning a little.  I grabbed my camera and drove down to our family prairie for a walk.  It was a beautiful day, with temperatures in the 50’s (F) and light winds.

Sun coming through dotted gayfeather in autumn prairie. Helzer prairie, near Stockham, Nebraska.
Sun coming through a dotted gayfeather seedhead in late autumn prairie. Helzer family prairie, near Stockham, Nebraska.

I rarely start these photo walks with a particular subject in mind, and yesterday was no exception.  I enjoyed looking at the bright red leaves on wild rose plants, and perused the tracks of various animals along the edge of the wetland.  However, I ended up spending most of my time photographing the seeds of dotted gayfeather (Liatris punctata) plants.

Dotted gayfeather in autumn prairie. Helzer prairie, near Stockham, Nebraska.
Dotted gayfeather seeds still hanging on.

While many plants with wind-blown seeds released the last of those seeds weeks or months ago, most gayfeather plants are still hanging on to most of theirs.  It’s hard to know if there is an evolutionary adaptation involved in that delay, but it sure is appreciated by photographers like me.  …Especially in late November, when wildflowers and insects have disappeared for the winter.

Dotted gayfeather in autumn prairie. Helzer prairie, near Stockham, Nebraska.
Dotted gayfeather in autumn prairie..
Dotted gayfeather in autumn prairie. Helzer prairie, near Stockham, Nebraska.
More seeds.
Dotted gayfeather in autumn prairie. Helzer prairie, near Stockham, Nebraska.
A big ‘ol jumble of seeds.

On this official day of Thanksgiving, I’m grateful for many things – including my job, which allows me to work in, study, photograph, and write about grasslands and prairie ecology.  More than that, I’m incredibly thankful for the opportunity to write this blog over the last five (!!) years.  Writing these posts forces me to explore more ideas and think more deeply than I otherwise would, and I learn a tremendous amount as a result.  Thank you for reading, following, and sharing your feedback.

Have a safe and enjoyable holiday.  Happy Thanksgiving!

Photo of the Week – August 28, 2014

I made a quick run out to our family prairie this week to see how our grazing management was looking.  It was a beautiful evening for a stroll, as the sun went down through layers of diffuse clouds.  The abundant rain this year has fueled tremendous growth in the prairie and has filled up the wetland to its rim.  As planned, a portion of the prairie is short-cropped by cattle grazing while other areas are either ungrazed or lightly grazed, and there was a lot of life on display.

Grasshoppers and katydids exploded around my feet as I walked around – most of them clearly adults since they were flying short distances before landing again (they only get wings after their final molt into adulthood).  They were joined by hordes of other invertebrates, including caterpillars, bees, butterflies, and many others.  I flushed a great horned owl from a big ash tree, and then was very pleased to see a rail (probably a Virginia rail) dangle its feet as it flew across our recovering wetland.  Here are a few photos from the night.

Caterpillar
I’ve seen this same species of caterpillar in a couple places this week.  This one was munching on false boneset.

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Dotted gayfeather and stiff goldenrod were both abundant upslope of the wetland.
Dotted gayfeather and stiff goldenrod were both abundant uphill from the wetland.

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A close-up view of dotted gayfeather.
A close-up view of dotted gayfeather.

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Our wetland at sunset.
Our wetland at sunset.  The addition of a couple solar-powered wells for livestock water has allowed us to exclude cattle from the pond/wetland area, and the habitat improvements are obvious.

A quick note of thanks:  This blog quietly passed two milestones this week.  I posted my 500th post, and we passed the 1,800 mark on blog subscribers.  Thank you for your continued support of this site – I hope it’s as useful and enjoyable to you as it is to me.

Photo of the Week – September 6, 2013

Here are three photos from the last couple weeks that didn’t fit into any particular story or theme.  Each is from a different prairie, and each was the result of a quick opportunistic stop in the midst of doing something else.  The pitcher sage photo (immediately below) came after I walked past a patch of the flowers and then backed up to capture the image that stuck in my head when I first walked past.  I noticed the soldier beetle (second photo) as I was walking back to take more photos of the praying mantis eating the sphinx moth.  Finally, I spotted the bee sitting on a dew-covered gayfeather flower (third photo) as I got out of my truck to work on a fence project at our farm.

Pitcher sage (Salvia azurea) in our plant diversity research plots.  Platte River Prairies, Nebraska.
Pitcher sage (Salvia azurea) in our plant diversity research plots. Platte River Prairies, Nebraska.

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A soldier beetle on a grass leaf.  Lincoln Creek Prairie - Aurora, Nebraska.
A soldier beetle on a grass leaf. Lincoln Creek Prairie – Aurora, Nebraska.

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A male long-horned bee (Melissodes sp) on dotted gayfeather (Liatris punctata).  Helzer family prairie - south of Aurora, Nebraska.
A male long-horned bee (Melissodes sp) on dotted gayfeather (Liatris punctata). Helzer family prairie – south of Aurora, Nebraska.

Photo of the Week – September 9, 2011

This week our Platte River Prairies are in full autumn regalia.  Everywhere you look, big yellow composite flowers, especially sunflowers and goldenrods, dominate the visual landscape.  At least 15 different species of yellow flowers are blooming right now.  They are set against the golds and purples of the warm-season grasses, which are also in full bloom. 

Maximilian sunflowers have just started to bloom, joining a crowded field of five other sunflower species in our prairies. (Click on the photo to see it full-screen)

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A grasshopper sits on one of the last remaining blossoms of stiff sunflower, an early blooming perennial sunflower - most common in the sandier soils of our prairies.

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Our seed harvest crew is swimming through the tall grasses and late yellow flowers to find ripe seeds from shorter plants that bloomed earlier this year. In this photo, Mardell Jasnowski (left) and Nanette Whitten (right) look for black-eyed Susan seeds in the burned/grazed portion of a prairie. A light stocking rate and an unexpectedly wet season has left even this grazed area with plenty of tall growth.

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The abundance of yellow makes flowers of any other color really stand out. In this photo, Mardell is harvesting seed near a particularly showy dotted gayfeather plant.

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This cluster of Maximilian sunflower blossoms was arrayed nicely for a photo...

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A tree cricket feeds on pollen from a stiff sunflower, while two grasshoppers do the same on another flower in the background. Tree crickets are omnivorous - feeding on both small insects and plant material.

In another week or so, some of the yellow flowers will start to fade, and the rest will be joined by the whites and lavenders of late season asters.  In the meantime, yellow is definitely the color of the week. 

Enjoy the autumn!