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The Center for Native Grasslands Management

Title: Restoration for a butterfly: Promoting grassland habitat components at Gettysburg National Military Park
Year: 2010
Author(s): Tilden, V., Boulton, A., Swartz, M., Hovis, J.
Source Title:
Source Type: Proceedings
pages: 47
Original Publication:  
Abstract: The only known stable population of the regal fritillary butterfly (Speyeria idalia) in the eastern United States is found at Fort Indiantown Gap (FIG) National Guard Training Center, PA. To aid in species recovery, a repatriation plan has been implemented at several sites, including Gettysburg National Military Park (GNMP), PA. This study tested three experimental treatments (solarization [an agricultural technique that traps heat under plastic to raise the soil temperature and reduce annual species and soil pathogens], disking, and mowing) on larval host plant (violets) density and survivorship of transplanted nectar plants (native milkweeds and thistles). The goal of this project was to assess the efficacy of these three treatments in relation to the growth and survival of host plants. Once the most suitable management method(s) has been identified, large scale replication can commence with the goal of creating functional grasslands for the repatriation of this butterfly. Vegetation was surveyed at GNMP in 2008, 2009, and 2010. Surveys assessed larval (rosettes/m2) and adult (stems/m2) host plant density within experimental plots. Subsequently, supplemental nectar transplants were planted and surveyed for survivorship. No significant treatment effect on larval host plant density (solarization x =4.92 +- 1.32; disk x =5.76 +- 1.51; mow =11.69 +- 3.63) or nectar transplant survivorship was found. Violet density increased significantly in 2009 and decreased in 2010. As of 2010, experimental plot violet density was five times greater than pre-treatment and three times greater than values at FIG in 2004. Nectar transplant survivorship was significant between species and year. In 2010, 5.2% of transplants had survived with Cirsium discolor as the most successful. Unfavorable weather conditions and transplant hardiness may have contributed to this low outcome. Overall, the presence of essential habitat components increased at GNMP because of this project, thus, improving site suitability and chances of a successful repatriation of this rare species in the future.
Publisher: Proceedings of the Seventh Eastern Native Grass Symposium. Knoxville, TN, October 5-8, 2010
Editor(s): C. Harper