RESEARCH AREAS & PROJECTS
Biodiversity and ecosystem services in agricultural landscapes
One of our main focus areas is understanding how agricultural practices at both local and landscape scales affect insect communities and the ecosystem services they provide. This has included work on:
How the structure of agricultural landscapes in the US came about, and whether we can intentionally design them at landscape scales to maximize arthropod diversity and ecosystem services (Review paper)
Whether we can use remote sensing to predict diversity of grassland plants and insects (more on this soon)
Targeted arthropod conservation and insect-plant interactions
Past projects have focused on conservation of targeted species, in both cases focusing on interactions between butterflies and their host plants. These have included:
Biodiversity impacts of bioenergy cropping
As we cope with climate change, agricultural landscapes are likely to transform as growers adopt bioenergy crops. This will have strong impacts on biodiversity, but their direction and magnitude will depend on which crops are adopted, how they are managed, and where they are grown. There are a wide range of crop types which range from annuals like corn to perennial grass monocultures or diverse native plant communities. Using a long-term experimental array at Michigan State University's Kellogg Biological Station, in 2021 we conducted broad biodiversity censuses (including plants, arthropods, vertebrates, and microbes) to see who lives in each crop. Stay tuned for publications on this work soon.
This work was funded by the Department of Energy Great Lakes Bioenergy Research Center.
Monarch butterfly conservation
The eastern migratory monarch population has declined since the 1990s, and scientists are trying to understand causes of the decline and what can be done about it. We've found that when common milkweed stems regrow after being cut back by disturbances (mowing, burning, etc.) they can receive several times more monarch eggs, contain fewer arthropod predators, and can have enhanced survival of early-stage monarch caterpillars.
This work was funded by USDA NIFA, MSU Project GREEEN and NSF LTER.
Collaborators: Doug Landis, Andrew Myers, Sara Hermann, and others
Haan, N.L., and Landis, D.A. 2020. Grassland disturbance effects on first-instar monarch butterfly survival, floral resources, and flower-visiting insects. Biological Conservation. Open access
Myers, A.T., N.L. Haan, and D.A. Landis. 2020. Video surveillance reveals a diverse and largely nocturnal community of monarch butterfly egg predators. Journal of Insect Conservation. Open acces
Hermann, S.L., Blackledge, C., Haan, N.L., Myers, A.T., and Landis, D.A. 2019. Predators of monarch butterfly eggs and neonate larvae are more diverse than previously recognized. Scientific Reports. Open access
Haan, N.L. and Landis, D.A. 2019. Grassland disturbance increases monarch butterfly oviposition and decreases arthropod predator abundance. Biological Conservation. Link
Haan, N.L. and Landis, D.A. 2019. The importance of shifting disturbance regimes in monarch butterfly decline and recovery. Frontiers in Ecology and Evolution. Open access
Endangered butterfly recovery, parasitic plants, and grassland management in the Pacific Northwest
Grasslands in the Pacific Northwest are home to several rare species with complex and sometimes conflicting management objectives. Taylor's checkerspot (Euphydryas editha taylori) is an endangered grassland butterfly. Managers needed information on its interactions with host plants, which include the common native species Castilleja hispida, the threatened native species Castilleja levisecta, and the weedy exotic Plantago lanceolata. As a PhD student I examined several aspects of its relationship to these hosts.
This work was funded by the Army Compatible Use Buffer program, NSF (DEB - 1556106), and the University of Washington Royalty Research Fund, and carried out with help from several conservation agencies and nonprofits including the US Fish and Wildlife Service, Washington Department of Fish and Wildlife, and Center for Natural Lands Management.
Collaborators: Jon Bakker, Peter Dunwiddie, Mary Linders, Deane Bowers, and others
Haan, N.L., Bowers, M.D., and Bakker, J.D. 2021. Preference, performance, and chemical defense in an endangered butterfly using novel and ancestral host plants. Scientific Reports 11. doi: 10.1038/s41598-020-80413-y. Open access
Haan, N.L., Bakker, J.D., and M.D. Linders. 2018. Instar-specific effects of host plants on survival of endangered butterfly larvae. Ecological Entomology 43,742-753. Link
Haan, N.L., J.D. Bakker, and M.D. Bowers. 2017. Hemiparasites can transmit indirect effects from their host plants to herbivores. Ecology 99,399-410. Link
Dunwiddie, P.W., N.L. Haan, M.J. Linders, J.D. Bakker, C. Fimbel, T.B. Thomas. 2016. Intertwined fates: opportunities and challenges in the linked recovery of two rare species. Natural Areas Journal 36,207-215. Open access
Taylor's checkerspot on one of its host plants, Castilleja levisecta
Castilleja hispida, a hemiparasitic plant and checkerspot host