Dissertations and Theses @ UNI

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Open Access Thesis

Abstract

The monarch butterfly (Danaus plexippus) is a migratory species whose primary breeding range is the upper Midwestern United States. In 2022, the International Union for the Conservation of Nature listed the monarch as endangered due to milkweed and migratory habitat loss. One of the most promising opportunities for monarch recovery is to enhance habitat quality on private land currently enrolled in the USDA Conservation Reserve Program (CRP). In order to qualify for re-enrollment in the program and continuation of annual government payments, farmers must show adequate habitat quality or enhance their site by overseeding after burning, herbicide application, or tillage. I asked whether this process, as currently implemented, would succeed in improving monarch habitat. In summer of 2021, I assessed vegetation on seventeen farms in eastern Iowa using Daubenmire cover classes and counted milkweed stem density utilizing random transects. Six sites on four farms were required to enhance their vegetation to re-enroll; surprisingly, end-of-contract habitat quality was not closely related to the requirement to enhance. Enhanced areas at sites averaged just 17% of the area original sites. I observed a significant decrease in warm-season grasses and vegetative cover. The relative cover of forbs and non-native grasses, as well as milkweed stem density, were not affected, while warm-season grass relative cover on average decreased 31.12%. Early germinating wildflower species that were provided to farmers for overseeding were established on all sites, demonstrating that enhancement disturbances did open the plant community for new plant establishment. More time is needed to assess whether habitat value for monarchs improved, but preliminary evidence was mixed. By surveying 2-3 years after the enhancement, we may obtain a more iii accurate picture of the outcome of the enhancements at each site. The study of private lands conservation programs has inherent limitations but is necessary for monarch butterfly conservation.

Year of Submission

2023

Degree Name

Master of Science

Department

Department of Biology

First Advisor

Laura Jackson, Chair, Thesis Committee

Date Original

5-2023

Object Description

1 PDF file (viii, 47 pages)

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