Adjunct Assistant Professor, Plant Biology and Conservation, Northwestern University
International Union for Conservation of Nature, Orchid Specialist Group
U.S. Fish & Wildlife Service Recovery Team Member: Platanthera praeclara and Lespedeza leptostachya
- Population biology and reproductive ecology of rare plants
- Effects of gender dynamics on population performance
- Plant population viability analysis
- Effects of climate change on rare plant species
- Modeling range shifts of plants under climate change
- Ex situ conservation
- Assisted migration of plant species in response to climate change
My research is focused on the reproductive ecology and population viability of rare and threatened plant species. I find population biology intriguing because it encompasses all aspects of plant performance, and involves the investigation of mechanisms that enhance or hinder that performance. Since the biology of each species is unique, and each population encounters a unique set of conditions, the quest to elucidate the biotic and abiotic mechanisms that affect performance across the geographic ranges of species is particularly important in this age of rapid environmental change and large scale human impacts on the landscape.
Species Range Shifts Under Climate Change
Many plant species will experience significant range shift as climate change proceeds over the coming decades, and seed recruitment is predicted to be one of the most at-risk stages in determining whether a species range will contract or expand. To address this, I am involved with a multi-institution, large-scale study integrating lab, field, and population modeling to test predictions about population-level responses to climate change. Looking at the demographic consequences of differences in seed dynamics across species’ ranges, we are investigating three species of Lespedeza, including the rare L. leptostachya, to assess how seed germination and seedling establishment respond to climate change, how this response affects population growth rates, and how our observed climatic niche breadth constrains species’ ranges now and in a climatically altered future.
Ex Situ Conservation
Seed banking both rare and common species is an important aspect of plant conservation. I curate the Dixon National Tallgrass Prairie Seed Bank at the Chicago Botanic Garden, which has a collection focus of native prairie species. We target the tallgrass prairie, because it is the most endangered ecosystem in North America, having lost approximately 96 percent of its former extent to habitat conversion. I am particularly interested in applying Geographic Information System (GIS) tools to create effective seed collection strategies.
Cirsium pitcheri (pitcher's thistle) — Cirsium pitcheri, is a threatened species endemic to the Great Lakes region of the US. Generally, the species is in decline due to numerous threats including invasive species, predation by goldfinches, and predation by up to three biocontrol weevils introduced to control weedy thistles. I have been involved in a long-term study of two populations on the Door Peninsula that are affected by these weevils to determine their effects on plant vital rates. I am also interested in elucidating the pollinator networks at these sites and how these interactions influence population viabilities. I work with Kay Havens-Young and outside collaborators on this project.
Lespedeza leptostachya (prairie bush clover) —This federally threatened gravel-hill prairie species is found at Nachusa Grasslands in Franklin Grove, Illinois, where we completed an experimental demography study to elucidate the role of grass competition on vital rates. Decreasing grass cover increases seedling recruit. Bison have recently been introduced to the study site and we are collecting data to determine their effects on grass cover, community composition, and vital rates of prairie bush clover.
Vitt, P., T.M. Knight, M. Schutzenhofer, W. Kleiman, K. Havens and T.R. Bittner. In Press. Experimental and Simulated Grazing in a Prairie Ecosystem Benefits Rare Forb. Natural Areas Journal.
Havens, K. and P. Vitt. In Press. The importance of phenological diversity in seed mixes for pollinator restoration. Natural Areas Journal.
Goad, R., S. Masi and P. Vitt. In Review. Long Term Projects and Retaining Citizen Scientists. in Citizen Science in Ecology and Conservation: A Practitioner’s Guide. Eds. Christopher A. Lepczyk, Mr. Timothy L. Vargo, Dr. Owen D. Boyle
Fox, K., K.M. Anderson, R. Andres, M.C. Foster, C.E. Foster, D. Vik, P. Vitt and M.O. Harris. 2015. Nectar Robbery and Thievery in the Hawk Moth (Lepidoptera: Sphingidae)-Pollinated Western Prairie Fringed Orchid Platanthera praeclara. Annals of the Entomological Society of America, http://dx.doi.org/10.1093/aesa/sav093.
Havens, K., P. Vitt, S. Still, A.T. Kramer, J.B. Fant and K. Schatz. 2015. Seed sourcing for restoration in an era of climate change. Invited Paper. Natural Areas Journal 35:122-133.
Guerrant, E. K. Havens and P. Vitt. 2014. Sampling for Effective Ex Situ Plant Conservation. International Journal of Plant Sciences. 175: 11-20.
K. Fox, P. Vitt, K. Anderson, G. Fauske, S. Travers, D. Vik and M. Harris. 2013. Pollination of a threatened orchid by an introduced hawk moth species in the tallgrass prairie of North America Biological Conservation 167:316-324.
Havens, K., C. Jolls, J. Marik, P. Vitt, A.K. McEachern, and D. Kind. 2012. Effects of an introduced biocontrol weevil, Larinus planus, and other emerging threats on populations of the federally threatened Pitcher’s thistle, Cirsium pitcheri, Biological Conservation 155: 202-211.
Schwartz, M.W.1, Hellmann, J.J.2, McLachlan, J.M. 2, Sax D.F.3, Borevitz, J.O.4. Brennan, J.5 Camacho, A.E. 6, Ceballos, G.7, Doremus, H.8, Early, R.3, Etterson, J.R.9, Gill, J. 10, Gonzalez, P.11, Green, N12, Hannah, L.13 Jamieson, D.W.14, Javeline. D.2, Minteer, B.A.15, Odenbaugh, J.16, Polasky, S17., Richardson, D.M.18, Root, T.L.19, Safford, H.D.1,20, Sala, O.15, Schneider, S.H.21, Thompson, A.R.24, Williams, J.W.10, Vellend, M.23, Vitt, P.24 Zellmer, S.25. 2012. Integrating the scientific, regulatory and ethical challenges posed by managed relocation. BioScience 62(8):732-743.
Knight, T.M., K. Havens and P. Vitt. 2011. Will the use of less fecund cultivars reduce the invasiveness of perennial plants? BioScience 61(10): 816-822.
Vitt, P. K. Havens, A.T. Kramer, D. Sollenberger, and E. Yates. 2010 Assisted Migration of Plants: Changes in Latitudes, Changes in Attitude. Biological Conservation 143 (1): 18-27.
Vitt, P. K. Havens and O. Hoegh-Guldberg. 2009. Assisted migration: part of an integrated conservation strategy. Trends in Ecology and Evolution 24: 473-474.
Vitt, P., T. Knight, and B.P. Kendall. 2009. Effects of Community Level Management on Agalinis auriculata, a Rare Non-Target Prairie Annual. Biological Conservation 142 (4): 798-805.
Vitt, P., K.E. Holsinger, and C.S. Jones, 2003. Local differentiation and phenotypic plasticity of size and gender change in Arisaema triphyllum. Am. J. Bot.