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Jared gave a presentation at the Chicago Plant Science Symposium on April 19th about our big prescribed fire experiment. He focused this talk on fire effects on plant reproduction & demography.  This is part of our project “How Do Prescribed Fires Affect Native Prairie Bees?” Funding for this project was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR).  In 2024, we harvested Echinacea in the remnants for Jennifer Ison’s pollinator observation study and at the Hegg Lake pallida restoration. For the pollinator observation study, we quantified reproductive effort on a given day and watched heads at different plants across 10 remnants. When a pollinator visited our focus head, we would take a video so we could later ID the pollinator. This pollinator observation was done by Ning on a plant at yohw this summer. I asked Ian to give his best ID and he thinks this is a Halictus species! Very cool. We harvested heads from plants involved in this experiment to get an idea of how observed visitation links up with realized seed set. In total, we harvested 136 heads and brought them back to the botanic garden for processing. Here are the detailed stats:
Again, please forgive rounding errors. This batch is the highest priority in the lab; volunteers are currently working on cleaning these heads and hopefully the rest of the ace process is soon to follow! We also harvested, or perhaps I should just say decapitated, Echinacea pallida at Hegg Lake WMA. This species is native to areas primarily south and east of our study site, such as Indiana and Arkansas. SO how did they wind up in Minnesota? Seed for pallida was accidentally included in a restoration effort by the MN DNR years back. This raised concerns for us about potential hybridization with our native Echinacea angustifolia. (If you want to learn more about angustifolia x pallida hybridization like we did, check out our experiments to that end!) In summer 2024, we once again conducted our civic duty and decapitated pallida heads at Hegg in an attempt to prevent reproduction and further spread. We sliced and diced a total of 523 heads this year, with the largest plant having 20 normal flowering heads! Wowza.  There was also one plant at the location we refer to as “near pal” that we suspected may be an escaped hybrid; that is, a plant that we believe may be a natural hybrid of angustifolia and pallida. This individual only had one head, but was taller and more robust than its angustifolia neighbors. We put a pollinator exclusion bag on the head to prevent pollen spread, and later harvested the head and brought it back to the lab, where it is currently in the seed dryer. Keep an eye on 29239 in the future… As part of the Echinacea Project’s long-term efforts to monitor reproductive fitness in the remnant populations, we harvested 124 Echinacea seed heads from 16 remnants during summer 2023. All sites burned in 2023 were included in remnant harvest selection and we also prioritized sites with small population sizes. We randomly selected heads from each population at the sites we visited. Harvesting seed heads and quantifying seed set can help us to better understand how the spatial location and flowering phenology of Echinacea contribute to reproductive fitness. However, this year, we did not conduct field work for phenology, so we were less interested in relating remnant harvest to phenology and spatial mating opportunities. Our primary focus was to examine fire’s affects on reproduction in different sized populations. We narrowed our remnant harvest efforts to small sites where extra data would be helpful in answering questions about how fire influences mating opportunities and seed set across different populations ranging in size. The heads harvested in 2023 are currently in the CBG lab. We have entered the harvest data, and the heads are awaiting inventory!  In order to ensure that we are not disrupting remnant populations, we return achenes to their maternal plants in a way that mimics natural dispersal after they have been processed in the lab. On a recent trip to Minnesota, we visited many small sites, where this process is essential as well as a few bigger ones.
You can read more about the reproductive fitness in remnants experiment, as well as links to prior flog entries about this experiment, on the background page for this experiment. Congratulations, Team Echinacea! We are done processing all of the Echinacea heads that were harvested from prairie remnants in 2020, 2021, and 2022. On Thursday, I completed the final step of the ACE process: freezing. We want to preserve some remnant achenes for future experiments, so we stored them in the seed vault freezer at the Chicago Botanic Garden. They are now documented in the seed bank database. Here’s a summary of the remnant Echinacea stored in the freezer:
With efficient packing, I was able to cram all of these achenes into two freezer bags. However, sealing the bags was definitely a two-person job. Echinacea from 2020 and 2021 are in one bag, and 2022 gets a bag all of its own. It feels very satisfying to wrap up these three years of data!   One of our main goals over the past two years has been to process all of the Echinacea harvested from remnants in 2020, 2021, and 2022 to investigate the effects of prescribed fire on flowering and fitness. We harvested 1,012 heads over these three years.
For each head, the end goal is to get an accurate count of the number of achenes and the seed set, a measure of pollination success. To collect these data, we sent the Echinacea through our high-throughput seed processing system, which we call the ACE process. (The true meaning of ACE is controversial: Always Cleaning Echinacea? Accurately Counting Echinacea? Achene Chaos Extraordinaire?) The ACE process has many steps: inventory, clean, recheck, scan, count, randomize, x-ray, classify, store. In spring 2023, we finished processing all of the remnant Echinacea from 2020, 2021, and 2022! We send a huge thank you to all the students and volunteers who put in many hours on this project over the last few years. We couldn’t have done it without you!        Jared is currently adding the achene count and seed set data to the remnant data repository on the Echinacea Project website. All achenes are currently in the dehumidifier at the Chicago Botanic Garden. After two weeks of drying, they can be stored in the seed bank. As part of the Echinacea Project’s long-term efforts to monitor reproductive fitness in the remnant populations, we harvested 330 Echinacea seed heads from 23 remnants during summer 2022. We randomly selected 15 heads from each population where we conducted phenology. If a population had fewer than 15 flowering plants, we harvested a randomly selected head from all flowering plants. In the fragmented populations we study, flowering plants often fail to produce viable seed due to limited mating opportunities. By harvesting seed heads and quantifying seed set, we can better understand how the spatial location and flowering phenology of Echinacea contribute to reproductive fitness. We are keenly interested in understanding how fire influences reproductive outcomes in fragmented prairies. To this end, we harvested seed heads from 7 populations experimentally burned during spring 2022. We will examine how fire influences mating opportunities and seed set across different populations ranging in size. The heads harvested in 2022 are currently in the CBG lab. Volunteers and students have cleaned, rechecked, and scanned all 330 heads, and they have randomized and x-rayed 249 of the heads so far. We are making great progress!  
You can read more about reproductive fitness in remnants, as well as links to previous flog entries mentioning the experiment, on the background page for this experiment. This summer, we harvested 330 Echinacea angustifolia heads from 23 prairie remnants. Remnant harvest started on August 16th and ended on September 14th, when we finally collected the last 4 heads, 3 at Steven’s Approach and 1 at Landfill West. We harvested the most heads on August 23rd, a total of 109 heads in one day. The heads are located in 15 gbags labeled RA-RP (there is no gbag RJ). We only visited sites where we recorded phenology this summer, so we harvested from fewer sites than last year. We did not harvest from Aanenson, East Elk Lake Road, Near Town Hall, On 27, Riley, Railroad, or Town Hall.  After Manogya and I completed data entry on the harvest list, I inventoried all of the bags that we brought back to the lab. There were a few mysteries to solve. We had several extra heads, but they mostly turned out to be heads that were supposed to be harvested, but someone forgot to check them off on the harvest datasheet, so it looked like they were missing. However, there was one perplexing puzzle that took some sleuthing to unravel. Two different people claimed to have harvested a head with a black twist tie from plant 18066 at Landfill West. In the lab, I found two heads with black twist ties labeled 18066, but I knew that they couldn’t both be the same plant. I donned my Sherlock hat and examined all the available evidence: survey, demography, and phenology data. From the survey data, I figured out that plant 18066’s neighbor, plant 27711, also had a head with black twist tie, so one of the duplicate heads was likely from the nearby plant. The phenology data revealed that 27711’s head had white gunk on it during the summer, and it had more rows of achenes than 18066’s head. Sure enough, one of the heads was larger than the other and had a speck of white on it. Mystery solved! I removed the imposter from the bag of heads to clean. The volunteers started cleaning the 2022 remnant heads on October 11th. They are currently working on gbag RE, bag 5 of 15, so they are making great progress. So far this year, we have sadly not been able to have volunteers in the lab due to the continuing threat of COVID-19. However, over the last few months, we made quite a bit of progress on the remnant Echinacea harvests from 2020 and 2021. In the fall, we had help from volunteers, students from Lake Forest College, and externs from Carleton College. Thanks for your help! In January, Sophia finished cleaning the last head from 2021, which was an exciting accomplishment. To track our progress in the lab, I created an R script to visualize the various steps of the ACE process for each batch of Echinacea. The figures for rem2020 and rem2021 are included here. Hopefully, this method will work for the cg harvests as well. The ACE stages are listed along the x-axis, and the number of Echinacea heads are on the y-axis. The light blue shows how much we have completed, and the dark blue shows what remains to be done. The small numbers on each bar indicate the corresponding number of heads, and the width of the bars is roughly proportional to the amount of time each step takes. Along the top, the dates indicate the last day that the totals for each stage were updated. The script to create these graphs can be found here: echinaceasandbox/oop/trackAceProgressTest.R As part of the Echinacea Project’s long-term efforts to monitor reproductive fitness in the remnant populations, Team Echinacea harvested 383 seeds heads from 29 remnants during summer 2021. We randomly selected 15 heads from each population to harvest. If a population had less than 15 flowering plants, we harvested a randomly selected head from all flowering plants. In the fragmented populations we study, flowering plants often fail to produce viable seed due to limited mating opportunities. By harvesting seed heads and quantifying seed set, we can better understand how the spatial location and flowering phenology of Echinacea contribute to reproductive fitness. We are keenly interested in understanding how fire influences reproductive outcomes in fragmented prairies. To this end, we harvested seed heads from 8 populations experimentally burned during spring 2021. We will examine how fire influences mating opportunities and seed set across different populations ranging in size. These heads we harvested are currently in the CBG lab being cleaned by volunteers and interns. We have even started scanning and counting achenes! Soon the new x-ray will be up and running, and we will begin to answer the burning questions we have about Echinacea reproduction in fragmented prairie remnants.
Start year: 1996 Location: Roadsides, railroad rights of way, and nature preserves in and around Solem Township, MN Overlaps with: Phenology in the Remnants Data/Materials collected: 383 seed heads were collected; these are currently at the Chicago Botanic Garden. Data sheets and other materials can be found here: ~Dropbox/remData Products: We will compile seed set data from 2021 into a dataset with seed set data from previous years. You can read more about reproductive fitness in remnants, as well as links to previous flog entries mentioning the experiment, on the background page for this experiment. After wrapping up our first remnant burn of the season at east riley, the crew ventured into the wild western prairies of Grant County. Earlier in the day, Mia mowed burn breaks at yellow orchid hill east. This roadside patch had considerably more fuel than east riley and NW winds remained stiff when we arrived. Once water buckets had been staged and the crew briefed, we ignited a test fire in the southeast corner. This fire backed beautifully against the wind, moving steadily and burning fuel completely. One of my takeaways from burns this spring is that prescribed burns in a little lower relative humidity (RH = 25-30) and a little higher winds (12-18 mph sustained) seem to produce great results in burn units where brome is the primary fuel. We decided to let the fire back against the wind across the entire burn unit. Once sufficient black had been established in the southeast corner of the unit, we ignited a backing fire along the entire southern edge of the unit along Wennersborg Rd. After fire lines were secured, Gretel grabbed the push power and finished mowing burn breaks at yellow orchid hill west while Jared, Stuart, and Mia extinguished any remaining hotspots. 30 minutes after ignition, we were left with an almost entirely blackened burn unit. Beautiful, predictable prescribed burn! Temperature – 53 F |
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