I’m Rebecca Lerdau, a Junior at Carleton College. I’ve had a great time these past three weeks as a Carleton College extern at the Echinacea Project. I, and my classmate, Vo Dominguez were working with Jared Beck on the RemAg project looking at Andropogon gerardii’s (big bluestem) reproductive response to fire.
Having a good time counting the X-Ray images
A big part of our work has been with creating new protocols for determining Andropogon seed set. Previously, the main method for finding Andropogon seed set has been dissecting every floret, but this isn’t realistic on a large scale. Around half of Andropogon’s florets aren’t able to produce seeds, but it can be difficult to distinguish between the two types of florets. We wanted to figure out a way to use inflorescence mass to find total amounts of florets that can produce seeds. We were able to count awns and look at the relationship between awn count and mass. We found a beautifully linear relationship between awn count and seed mass (our R^2 = 0.96!) which allowed us to make an equation to use mass to determine the amount of fruiting florets. We set out to try X-raying Andropogon to determine seed counts. This was also successful, and we created a classification system for counting seeds with X-ray images.
We also got to try out our new seed set quantification system on some samples from the pilot RemAg experiment. We looked at the effects of burning on Andropogon seed set in 2022 from the pilot plots. While we were unable to find significant results with the data we were looking at, it was good to see that our protocols were working. The protocols are promising, and I look forward to seeing what happens with the larger RemAg project!
All in all, it’s been an awn-some experience working as an extern these past few weeks. I’ve learned so much. I’ve enjoyed getting to meet scientists and exploring CBG. We went on some lovely walks and got to see all sorts of cool plants. I had fun working with Andropogon and we even found a few seed predators! Thank you to Stuart, Jared, Wyatt, and Abby for this experience, and thank you to my fellow externs as well.
Biology Major with a focus in Ecology and Evolution, Carleton College, 2025
Pronouns: They/Them
Research Interests
Evolutionary ecology, prairie restoration with a focus on fauna community interactions to restored prairies, bees, anteaters, a number of other things.
Statement
I just had a great time working with the Echinacea project (or should I say Andropogon project) for a three week long externship with Carleton college.
My classmate, Rebecca Lerdau, and I were brought on to work with Jared Beck on the RemAg project, looking at big bluestem’s (Andropogon gerardii) response to fire.
We wrote a new protocol for assessing seed sets (the number of pollinated seeds divided by the number of viable fruits produced by an individual plant) for big bluestem. Previously, the only methods for assessing seedset in big bluestem involved dissecting individual seed cases. This method is extremely time consuming, and Echi-nation sustains too many seeds and not enough time or spare under-graduates for it to be a viable protocol for the scope of the RemAg project. Because of a lack of lab protocols for assessing big bluestem seed sets, this project has been sitting on hold in Jared’s office for a while, and we were really excited to help get it moving.
We found a strong relationship between the mass of subsamples of grass florets and the number of awns, a structure found only on perfect, viable Andropogon florets which allowed us to use mass to calculate awn count and awn count as a proxy for fruit count.
We also developed protocols for classifying florets and pollinated (containing a seed) or unpollinated (not containing a seed) from X-ray images. Using the number of pollinated seeds counted from the X-ray to calculate seed count and the awn count approximated by mass for the fruit count, we are able to efficiently classify big bluestem seed sets.
We used our methods to analyze some samples from a pilot RemAg study. Despite some issues with the study design, we were able to prove the feasibility of using our lab protocols to analyze RemAg data.
It’s been a great three weeks working with the Echinacea Project. I have greatly enjoyed making awn-some puns with my collaborators, meeting people at the botanic garden, inhaling Andropogon smut fungus, and proving to my family that I am a real biologist who knows how to use an x-ray machine. Thank you to Stuart, Jared, Wyatt, and Abby for making this experience possible.
We established an experiment in 2021 to investigate the effects of fire on Big Bluestem (Andropogon gerardii). reproduction. For the third year, we visited 378 randomly placed plots across 27 remnant patches and counted the number of flowering Andropogon culms rooted within 1 m of the random point. We also harvested seed heads to directly examine reproductive outcomes. In 2023, we counted a total of 1814 culms. The highest density we observed was 165 culms in one plot at KJs, but it wasn’t enough to beat the standing records from 2022 of 197 culms…
With the help of Elif and Carleton externs, we are making progress on a protocol that will enable us to efficiently quantify seed production. Stay tuned!
Should we tell Lindsey that isn’t an Andropogon plot? Nah, what’s the worst that can happen…
Start year: 2021
Location: 27 patches of talgrass prairie near Solem Township, MN
Data collected: All reproductive effort data have been curated and are housed in remag repo.
Samples or specimens collected: Seed heads collected during summer 2023 are in Jared’s office. These samples will be cleaned, processed, and x-rayed to quantify seed set. All 2021 samples have been cleaned and weighed. Most 2022 samples have been cleaned and weighed. All samples will be x-rayed this winter.
Products: Stay tuned!
You can read more about the Andropogon fire and flowering in remnants experiment, as well as links to prior flog entries about this experiment, on the background page for this experiment.
In late summer 2021, we began collecting data in remnant patches of prairie to quantify fire effects on the reproduction of Big Bluestem (Andropogon gerardii). In summer 2022, we revisited the same 378 random points across 27 remnant patches and counted the number of flowering Andropogon culms rooted within 1 m of the random point. Across the 378 plots, we counted 2442 culms. The highest density we observed was 197 culms in one plot at Loeffler Corner West, which beats our record from last year, 163 culms at KJs.
We also collected seed heads from all culms within 1 m of the random points to x-ray and quantify seed set. We initially visited random points on September 8, but some of the Andropogon was not ready to harvest, so we returned a few days later. We finished harvesting on September 19. In the lab, Elif has been developing a cleaning and x-ray protocol for Andropogon. Stay tuned for more details!
Manogya harvests Andropogon at Loeffler Corner West
Start year: 2021
Location: Patches of remnant prairie in and around Solem Township, MN
Data collected: Field datasheets are located in Dropbox: ~burnRems\remAndro\fieldData2022\remAndro2022DataSheet.scanned.pdf. We still need to do data entry.
Samples or specimens collected: Seed heads collected during summer 2022 are currently in the seed dryer but will reside in Jared’s office. These samples will be cleaned, processed, and x-rayed to quantify seed set.
Products: Stay tuned!
You can read more about the Andropogon fire and flowering in remnants experiment, as well as links to prior flog entries about this experiment, on the background page for this experiment.
During late summer 2021, we began collecting data in remnant patches of prairie to quantify fire effects on the reproduction of Big bluestem (Andropogon gerardii). We visited 376 random points established during the summer across 27 remnant patches and counted the number of flowering Andropogon culms rooted within 1 m of the random point. Across the 376 plots, we counted 1450 culms. The highest density we observed was 163 culms in one plot at KJs. We also collected seed heads from all culms within 1 m of the random points to x-ray and quantify seed set.
Jared searching in vain for Andropogon culms at Staffanson.
Start year: 2021
Location: Patches of remnant prairie in and around Solem Township, MN
Data collected: ~Dropbox/burnRems/remAndro/fieldData2021/remAndro2021DataVerified.csv
Samples or specimens collected: Seed heads collected during summer 2021 have been dried and currently reside in Jared’s office. These samples will be cleaned, processed, and x-rayed to quantify seed set.
Products: Stay tuned!
You can read more about the Andropogon fire and flowering in remnants experiment, as well as links to prior flog entries about this experiment, on the background page for this experiment.
As summer’s vibrant greens give way to fall’s golden glow, Team Echinacea remains hard at work in western MN. A skeleton crew is diligently wrapping up the field season. Our most important task is harvesting seed from study species so that we can quantify fire effects on plant reproduction in remnant prairies. Here is a brief update on progress for our focal species:
Asclepias viridiflora: all plants harvested (~30, Jared forgot to check harvest data sheet…)
Oenothera biennis
Cirsium flodmanii
Prenanthes racemosa
Gentiana puberulenta
Just a few end of season friends enjoying the late summer sun.
In addition to wrapping up the harvest, we are beginning to make preparations for fall burns and getting materials organized to implement a seed addition experiment designed to assess fire effects on seedling emergence and survival.
Taking a break from work to enjoy an afternoon at Seven Sisters.
This morning (Wednesday), I got a bit of a late start because I made a double-batch apple crisp this morning, and the apples weren’t quite cooked yet. For the crisp, I used combination of northwest greening and haralred apples from the trees around Hjelm, and Mia and Wesley kindly helped me slice up the mountainous 8 cups of apples. When the crisp had finally cooked, I met up with Mia and Wesley, who had just finished adding stapes in p1. (check!)
Wednesday morning apple crisp
Next, Wesley and I headed out with Collins to finish up total demo at tplot and shoot a few more flowering plants at hegg in an area which is being renamed nrpal, or near pallida. Total demo is now done! (check!)
Bottle gentian at hegg
After lunch, Wesley and I tackled the remainder of the Andropogon harvest sites. Our record was a plot at kjs with 163 Andropogon culms! Andropogon harvests are now complete. (check!)
Daily Andropogon haul
In the evening, we had another bonfire, and we were joined by Stuart’s parents. The rest of the crew cooked up some fabulous breakfast burritos for dinner, crowned with Mia’s famous pickled red onions. The wind had been gusting all afternoon, and now it pitched in to help fan the flames of the bonfire, which caught rapidly. We ended the day with some delicious home-grown apple crisp!
We’ve been missing Laura, John, and Kennedy this week, but we’ve had to forge ahead without them. Today, Mia and Wesley finished rechecks while I staked random points at nice, eth, and koons for our Andropogon expedition later in the day. After staking, I met with Stuart to learn some R-Studio data wrangling skills. At lunch, Wesley reported on the Liatris pollinator observations – the team conducted 95 total observations this summer and mapped over 2,500 plants!
Wesley with the original Liatris plant: LA1
After lunch, we learned a new protocol for harvesting Andropogon gerardii (big bluestem). We visited a third of the random points at each site and counted and harvested all the Andropogon culms within one meter of the point. Jared and I collected three full bags of Andropogon at East Riley, a site which had been burned, but we didn’t find a single culm at the other sites (spp and on27).
Jared searching for Andropogon at Staffanson
After work, the Elk Lake house spent all evening cooking up a giant batch of Wesley’s peanut noodles in preparation for the bonfire tomorrow night. Mia wisely used the food processor to grate the carrots, so no fingers were lost. We doubled the recipe, so there were an awful lot of carrots!
