Abstract
Much of the remaining suitable habitat for monarchs (Danaus plexippus) in Minnesota is found in tallgrass prairies. We studied the association of adult monarch abundance with use of fire or grazing to manage prairies. Sites (n = 20) ranged in size from 1 to 145 hectares and included land owned and managed by the Minnesota DNR, U.S. Fish and Wildlife Service, The Nature Conservancy, and private landowners. We measured Asclepias spp. (milkweeds, monarch host plants) and forb frequency in 0.5 × 2-m plots located along randomly-placed transects that were stratified to sample wet, mesic, and dry prairie types at each site. Adult butterfly surveys took place three times at each site during the summers of 2016 and 2017, using a standardized Pollard Walk (400 m). Data were analyzed using mixed effects models. Monarchs were more abundant at sites managed with prescribed fire than with grazing. We found no difference in milkweed and forb frequency between burned and grazed prairies. There was no relationship between monarch abundance and the other predictor variables tested: milkweed frequency, site area, forb frequency, and percent prairie in a 1.5 km buffer area surrounding each site. Monarch abundance was lowest at grazed sites with high stocking rates. Our findings suggest that milkweed and forb frequency do not vary between burned and grazed sites, although we only considered land management practices for the 12 years before the study and the most recent burns occurred in 2014, 2 years prior to the start of our study. They also suggest that heavy grazing may have negative impacts on monarchs.
| Original language | English (US) |
|---|---|
| Article number | 435 |
| Journal | Frontiers in Ecology and Evolution |
| Volume | 7 |
| DOIs | |
| State | Published - Nov 14 2019 |
Bibliographical note
Funding Information:Thank you to scientists and land managers at the U.S. Fish and Wildlife Service, The Minnesota Department of Natural Resources, The Nature Conservancy, and private land owners for sharing resources, land, permits, site access, and management history. Thank you to the botanists and field technicians who helped collect data. We are grateful to Brian Aukema and Deb Buhl for providing valuable advice and feedback on statistical analyses, Erin Treiber for reviewing an earlier version of the manuscript, and Alex Leone for providing database and programming expertise and support. This paper has been improved through conversation with Myron Zalucki. Any use of trade, firm or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Funding. Funding for this project came from the Minnesota Environment and Natural Resources Trust Fund (ENRTF), M.L. 2015, Chp. 76, Sec. 2, Subd. 03o; Prairie Biotic Research, Inc.; National Science Foundation Graduate Research Fellowship (GRFP).
Funding Information:
Funding for this project came from the Minnesota Environment and Natural Resources Trust Fund (ENRTF), M.L. 2015, Chp. 76, Sec. 2, Subd. 03o; Prairie Biotic Research, Inc.; National Science Foundation Graduate Research Fellowship (GRFP).
Publisher Copyright:
© 2019, At least a portion of this work is authored by Diane L. Larson on behalf of the U.S. Government and, as regards Diane L. Larson and the U.S. Government, is not subject to copyright protection in the United States. Foreign and other copyrights may apply.
Keywords
- Asclepias
- Danaus plexippus
- conservation grazing
- milkweeds
- monarch butterfly
- prairie management
- prescribed fire
- tallgrass prairie