Habitat fragmentation decouples fire-stimulated flowering from plant reproductive fitness

This page has information about the Echinacea Project paper that was published in PNAS on 18 Sept 2023.

Updated 2 October 2023.

A flowering head of the narrow-leaved purple coneflower (Echinacea angustifolia). Credit: Jared Beck
A prescribed burn of a prairie restoration. Credit: Stuart Wagenius.

Seeking collaborators for fire and fragmentation experiment in western Minnesota

The Echinacea Project is seeking collaborators interested in studying the ecological effects of fire within a highly fragmented prairie landscape. In 2021, we began experimentally burning patches of remnant prairie in western Minnesota to investigate how fire effects on plant reproduction and population dynamics may be mediated by fragmentation. In 2023, we are expanding our efforts to study fire and fragmentation effects on plant-pollinator interactions and ground-nesting bees in remnant and restored prairies. We hope to collaborate with other researchers who can capitalize on our landscape-scale experiment to address these and other ecological questions about effects of fire and fragmentation in tallgrass prairie. Please share with anyone you think may be interested!

We will host a brief informational Zoom meeting on February 22 at 10:30 AM CDT to share information about the experimental design and potential opportunities for collaboration. If you are interested in attending the informational meeting, send us an email (EchinaceaProject [at] and we will share a link to the Zoom meeting. If you are unable to attend live, we plan to record the informational meeting and can make this recording available.

Stuart and Jared burn a prairie remnant

burning lcw 2022

After finishing up at nice island, our crew departed for the next set of burns. Our hope was to burn Loeffler’s Corner west as well as an adjacent 10 acre unit with gorgeous prairie hills. Unfortunately, minor delays and a couple bureaucratic hurdles outside of our control slowed us down. We chose to prioritize the smaller lcw unit (~2.25 acres). We ignited a test fire in the southeast corner of the burn unit and secured the southern burn break. Once a little black had been established, Stuart and Dwight began lighting along the eastern edge of the burn unit while Brad and I ignited along the western edge. Per and Ed patrolled the break and Alex monitored the weather. This was another slow burn through mostly brome. Around 4:45 PM, the winds began to die down so we hurried to ignite a headfire along the northern edge of the unit in an effort to avoid putting smoke on Hwy 55. Although the fire closed slowly, the burn was quite thorough and will help set back brome. Stuart and I were reminded of the lce burn from spring 2021 in which nearly the same situation unfolded just across the road. The projected stiff north winds lost their energy resulting in light and variable winds. We suspect local topography may be to blame.

Temperature: 67 F
Relative Humidity: 34 %
Wind Speed: 12 mph
Wind Direction: NNW
Ignition time: 4:06 PM
End time: 5:27 PM
Burn Crew: Jared, Stuart, Alex C., Per, Dwight, Ed C., Brad D.

burning nice island 2022

After navigating uncertainties about weather and electricity, we ventured up to western Minnesota for a promising burn window. Steady northwest winds, dry fuels, and suitable conditions left us eager to burn on Monday, May 16. Alex, Per, Stuart, and I worked all morning to ready burn breaks in preparation for the afternoon. We were joined by Brad D., Dwight, and Ed C.

Our first unit of the afternoon was the ironically named “nice island.” This unit comprises an eggplant-shaped peninsula of grass extending into an agricultural field. We are studying Green Milkweed and Rough Blazing Star reproduction at this site. After taking weather, discussing the burn plan, and orienting new crew members to their tools, we ignited a test fire in the southwest corner of the unit. The crew then split in half. One group secured the eastern burn break while the second group ignited and secured the western burn break. Once sufficient black had been established, Brad ignited west along the northern edge of the unit while I ignited east along the southern edge. Our hope was the fire would close on itself rapidly but this burn was much slower and smokier than expected (probably owing to the higher relative humidity and the abundance of brome that had greened up after rain and warm temperatures). Slowly but surely, the flames came together leaving a uniformly black burn unit. We are excited to see a nicer post-burn version of nice island this summer.

Temperature: 64 F
Relative Humidity: 44 %
Wind Speed: 11 mph
Wind Direction: NW
Ignition time: 1:32 PM
End time: 2:29 PM
Burn Crew: Jared, Stuart, Alex C., Per, Dwight, Brad D., Ed C.

burning btg 2022

After completing the nwlf burn on May 6, we packed up and drove south taking the scenic route to btg. Our goal was to get a look at TNC’s Staffanson west burn. Just north of the intersection of Hwy 27 we spotted a Swainson’s Hawk. Stuart noted this is the first time he has seen a Swainson’s Hawk in Douglas County. The Staffanson burn was ongoing, though the north and west lines were solid black. We circled around to btg in time to see a large column of smoke rising from Staffanson west. Presumably this was the head fire hitting the kettle pond.

Unlike the prior burn units, we had just received permission to burn btg and were not able to mow breaks. We decided the best course of action would be igniting along a wet line on the western and southern edges of the burn unit. We took weather, walked the unit, divided up responsibilities, and ignited a test fire. Stuart and Trygg wet lined down the western edge while I ignited. Upon turning the corner along the southern line, the more southern wind picked up and pushed a head fire across btg. The result was pretty good coverage and an efficient burned. Once the smoke dissipated, we packed up and returned to the farmhouse. Our plan was to burn Jean’s prairie garden quickly and then divide up. Alex and Trygg would take the GPS unit to shoot the boundaries of burn units while Stuart and Jared put away equipment.

Six experimental burn units in one afternoon… not too shabby.

Temperature: 69 F
Relative Humidity: 30 %
Wind Speed: 13 mph
Wind Direction: SSE
Ignition time: 4:35 PM
End time: 4:50 PM
Burn Crew: Jared, Stuart, Alex C., Trygg

burning nwlf 2022

Continuing our May 6 burning adventures, we departed mapp and drove west to nwlf. Our goal was to burn nwlf when conditions were most extreme to maximize burn coverage at nwlf.

After arriving at the site, staging equipment, and taking weather, I ignited a test fire in the NW corner of the unit. We were pleased with fire behavior and went ahead with securing the north edge of the burn unit. After rounding the tricky northeast corner, I tried extending the black in the ditch with little success. The fire did not carry well in the bottom of the ditch. We decided the best course of action was to ignite along the eastern edge of the unit before igniting in the ditch. I used a lot of fuel in the bottom of the ditch. This generated a lot of smoke but didn’t dramatically improve burn coverage in the bottom of the ditch at the north end of the unit. I ignited one more line along the western edge of the unit for good measure. The smoke soon subsided and we were left with a sufficiently charred ditch to leave us proud of our work. We packed up and departed for our last remnant burn of the afternoon.

Temperature: 69 F
Relative Humidity: 31 %
Wind Speed: 13 mph
Wind Direction: SE
Ignition time: 3:30 PM
End time: 3:58 PM
Burn Crew: Jared, Stuart, Alex C., Trygg

burning mapp 2022

Upon completion of our waa burn on May 6, we ventured north to mapp. After a quick discussion, we decided to enlarge the unit by ~10 m to the west just in case there were any Echinacea plants lurking outside the area where plants have flowered in the past. Stuart ignited a test fire in the NW corner. We installed a wet line along the western edge of the unit and Stuart ignited along the north edge. We secured the eastern edge where fuels were a bit heavier and watched the interior of mapp burn slowly and patchily. The thin film of silt seemed to prevent litter from burning in spots. We tried igniting unburned patches in the interior but soon concluded it was not worth the effort. We were eyeing at least two more burns and wanted to move quickly. While packing up equipment, we noticed a large plume of smoke rising from Staffanson!

Temperature: 68 F
Relative Humidity: 31 %
Wind Speed: 11 mph
Wind Direction: SE
Ignition time: 2:45 PM
End time: 2:58 PM
Burn Crew: Jared, Stuart, Alex C., Trygg

burning waa 2022

After conducting a successful burn in the pilot Andropogon plot and eating lunch on May 6, we packed up our equipment and ventured over to waa to conduct two prescribed burns. Echinacea within two small patches at waa separated by ~100 meters. We chose to burn two small patches given our time constraints and the prairie restoration with lots of fuel immediately to the north. Plus Douglas County Parks plans to burn the restoration and ditch within the next couple years.

After staging equipment and taking weather, we ignited a test fire in the NW corner of the western unit. Fire behavior looked good so we secured the western edge of the unit before igniting along the northern edge. Stuart did what he could with the drip torch but the burn was patchy and crept slowly. Light and discontinuous fuels made a thorough burn impossible but the Echinacea patches burned well so we moved on to the east unit.

Our procedure was identical for the eastern burn unit: test fire, secure western edge, ignite along northern edge, go back with drip torch to ignite unburned patches to the best of our ability. Fuels in the eastern unit were more continuous but also greener. The eastern unit of waa was also somewhat patchy but the patches of Echinacea experienced good fire and we had our eyes on additional burns…

Temperature: 69 F
Relative Humidity: 31 %
Wind Speed: 6-10 mph
Wind Direction: SE
Ignition time (west): 1:47 PM
End time (west): 2:00 PM
Ignition time (east): 2:08 PM
End time (east): 2:35 PM
Burn Crew: Jared, Stuart, Alex C., Trygg

April showers bring May fires

A cold, wet spring put an early damper on our 2022 burn season but we got a great start this week with an efficient two-day trip to Minnesota. The weather looked sufficiently warm and dry to justify the trip from CBG. Our goal was to prep burn units in anticipation of better burn weather. Stuart and I thought there was an outside chance we might be able to burn P1 or the Andropogon pilot plot on Friday but conditions were far better than anticipated. Fuels were dry and steady south winds brought drier air. We focused our efforts Thursday on preparing burn units. Alex and I mowed/raked breaks at waa and mapp in the morning. Stuart joined us after lunch to scout lcw, mark the burn unit boundary at lfw, and remove a handful of pine and cedar trees within the unit. Alex and I finished the day by mowing breaks at nwlf and cutting breaks at sgc.

The weather conditions that materialized Friday were ideal for prescribed burns: steady southeast wind, high temperatures in the mid 60s, relative humidity dipping to 30-35 percent, and good smoke dispersal. We were able to burn six experimental units and one bonus prairie garden between 11 AM and 6 PM. The Echinacea Project was not alone. TNC burned the western half of Staffanson on Friday and USFWS burned several WPAs. It was a very successful and efficient trip. Stay tuned to the flog for more detailed information about each experimental burn.

Updating and maintaining prescribed fire equipment

With a busy burn season ahead of us, I took some time in late October to maintain the equipment we use for prescribed burns. During a hectic spring 2021 burn season, we encountered several issues. A handful of 5-gallon backpack pumps were not functioning well and one of our drip torches was constantly acting up (especially while using the leftover “spicy” fuel mix).

During spring 2021, I noticed two of our 5-gallon backpack pumps had cracked pump cylinders and would need to be replaced. I tried applying plumber’s epoxy to the cracked cylinders last spring but the pressure created by the pump inevitably caused this epoxy to fail. Over the summer, we purchased replacement outer cylinders for the backpack pump assemblies. I rebuilt the pump assemblies and installed these cylinders last week. The pumps seems to be working properly now. We should be very diligent about making sure all water has been expelled from tanks and pump assemblies prior to winter storage to avoid cracked cylinders.

We also purchased four harnesses and two pairs of padded straps for our 5-gallon pumps. These provide a welcome upgrade over the notoriously uncomfortable thin straps that come with the backpack pumps. We now should have 6 fully functional (and comfortable!) backpack pumps for burning.

Rebuilding the troublesome drip torch was a priority for me. After inspecting the torch, I realized one if not the problem was a badly deteriorating collar gasket (the big O-ring). I replaced this gasket along with the smaller O-ring on the discharge plug. Pro-tip: Forestry Suppliers sells discharge plug O-rings for drip torches but the ones they sell are too large. I found the #9 O-rings (5/8 in. outer diameter x 7/16 in. inner diameter x 3/32 in. wall) that are readily available at just about any hardware store work much better. I also replaced the breather valve assembly on this drip torch.

This brings up a more general point about the importance of maintaining burn equipment. At the beginning of the burn season we should:

  • Check to make sure all 5-gallon backpack pumps are functioning properly
    • Check to make sure gasket is intact and installed in top lid
    • Inspect pump cylinder for cracks
    • Inspect nozzle and make sure it is clear of debris
    • Install paper clip used to clear nozzle obstructions
    • Ensure nozzle is set on adapter with two holes (single hole adapter not very effective or water-efficient for extinguishing grass fires)
    • Fill each tank with water and test pump
  • Check drip torches
    • Inspect integrity of collar gasket, replace immediately if damaged
    • Inspect integrity of discharge plug O-ring, replace if damaged
    • Check for obstructions or debris that could impede flow of fuel
  • Rakes and swatters
    • Locate metal rakes and swatters
    • Check integrity of the swatters (these can melt and deteriorate making them ineffective)
    • Note any tools that need replacing
  • Kestrel
    • Locate Kestrel 3500FW and test unit/check battery
    • Locate or purchase additional (new) battery

At the end of the season:

  • 5-gallon backpack pumps
    • Ensure all water and excess moisture has been expelled from 5-gallon pumps
    • Inspect integrity of gasket on tank lid
  • Drip torch
    • If empty, use paper towel to clean interior and remove debris
    • Check integrity of collar gasket and discharge plug O-rings
  • Return rakes and swatters to G3
  • Hang Kestrel 3500FW from wooden dowel above shelf between main room and bathroom in Hjelm