Ecological Structure and Function of Bioretention Cells Dissertation Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By David M. Wituszynski Graduate Program in Food, Agricultural & Biological Engineering The Ohio State University 2020 Dissertation Committee Dr. Jay Martin, Advisor Dr. Mary Gardiner Dr. Stephen Matthews Dr. Ryan Winston 1 Copyrighted by David M. Wituszynski 2020 2 Abstract There is an urgent need to increase the habitat value of cities, both for human health and for conservation. Constructed Green Infrastructure (GI), which uses vegetated areas to solve engineering problems such as stormwater mitigation, is an attractive option for habitat creation, and ecological engineers, with their stated goal to design for both human and natural benefit, should be key players in its design and implementation. However, ecological engineers are hampered by the lack of a suitable reference by which to evaluate the ecological goals of the GI which they design. They are further hampered by the lack of information about the ecology of many common GI practices. Bioretention cells (BRCs) are the most common form of green infrastructure used for stormwater management. Much work has been done to evaluate the hydrological and pollutant-removal capabilities of BRCs, but there has been comparatively little investigation of the ecological properties of these systems. This is a critical gap in knowledge, as ecological design of BRCs could not only increase their functioning as stormwater infrastructure but could also contribute ecological value to urban areas. Investigation of the habitat value of BRCs could lead to design techniques that subsidize and/or prioritize habitat creation in tandem with stormwater management, allowing ecological engineers to capitalize on the current popularity of this practice to improve urban habitat for both humans and non-humans. ii I address this gap in knowledge with a multi-taxon survey of biodiversity in BRCs installed as part of a large-scale retrofit of GI in Columbus, OH. I developed and validated a protocol to survey birds with automated acoustic monitoring – a first in an urban area – and determined that BRCs affected bird community composition during spring migration but not during the summer breeding period. BRCs did not generally harbor more species than lawns, but nearby remnant ravines appeared to increase species richness at both BRC and lawn sites. I also sampled ground-active arthropods with pitfall traps and identified carabid beetles to species. Carabid communities in BRCs were different from those in nearby lawns and ravines, indicating the ability of BRCs to host biologically unique assemblages in this urban area. These findings suggest that BRCs have the potential to significantly contribute habitat value to urban areas. I integrated the above findings, along with sampled vegetation volume and diversity, into a comprehensive measure of ecosystem health following the Vigor- Organization-Resilience model. BRCs scored higher than either lawns or ravines in this system, across a variety of metrics, reinforcing their potential ecological value. This technique, which is based on standard wildlife sampling strategies, has great potential in allowing ecological engineers to quantify their success is meeting their ecological design goals, alongside their societal ones. Much work remains to be done in calibrating the technique across a diversity of ecosystems, both constructed and natural, and in investigating other aspects of the ecology of BRCs. However, this study suggests that BRCs have potential to elevate the ecology of urban areas, and encourages ecological engineers to more closely consider the ecological aspects of their designs. iii Dedication To the Lunch Bunch For suffusing these many years in graduate school with friendship, meaning, and joy and for making real to me the doctrine of Adoption iv Acknowledgments So many people have contributed to my journey through graduate school, and I’m sure I won’t be able to mention all of them. Thanks first to the folks in the Food, Agricultural, and Biological Engineering department at OSU – not least our graduate coordinator Candy McBride, who kept me on track and kept me honest. The graduate students in our department have provided a supportive and welcoming environment since the day I first interviewed. Special thanks to the Martin lab for journeying alongside me, and particularly to Abigail Tamkin for unwavering friendship and support. Thanks to Noel Aloysous and Mike Brooker for much, and continual, help with R code. I was fortunate to be given space in Mary Gardiner’s lab when it was time for me to learn how to identify carabid beetles: thanks to all the lab members for welcoming me, and especially to Katie Turo, my first friend in the lab and my source of 11-th hour insect sampling advice. Kayla Perry generously shared her knowledge of pitfall trapping and Carabid identification, many times, and also invited me to a Carabid identification seminar she taught, which finally gave me confidence in that work. Much of this work was funded by a grant from the City of Columbus Division of Sewerage and Drainage. I’d like to express my appreciation for their being willing to fund a project that went beyond their reporting requirements, and for their even-handed v support throughout. Particular thanks to Mathew Repasky, our main contact at the city, for his patience with me as I labored over the results, and to Kari Hiatt, who provided me with valuable information about the vegetation in the bioretention cells. 23 different households in the Clintonville neighborhood graciously allowed me to set up microphones and/or insect traps in their front yards, and have endured regular visits from myself and a large group of undergraduate workers over the past three years. My thanks for their willingness to contribute to this project, and for their good humor. This work was facilitated by many, many undergraduate helpers – without them I would not have been able to collect the large amount of data that goes into a project of this kind. A few of them stand out: Joey Smith and Kate Boening went on to become graduate students in our department, and eventually took over the stormwater sampling part of the project, which allowed me to focus more effectively on the work presented in this dissertation. Gautam Apte was my go-to person for bird identification help: we spent many hours reviewing the recordings together and arguing over which birds might be making the stranger sounds. And Jack Hudak sorted all of the insects we caught, pinned all the carabids, conducted the 2019 vegetation sampling almost single-handedly, and in general held the insect project together. I am grateful for his many contributions. Two organizations have contributed greatly to my development as a scholar. One is the Au Sable Institute’s Graduate Fellows program, which I was able to join in the early part of 2014. My first interaction with them – a visit with Wendell Berry – helped convince me I should stay in Columbus after obtaining my Masters degree; they therefore bear no small responsibility for my decision to pursue this doctorate. The Au Sable vi fellows have been responsible for a great deal of my own intellectual formation, and I owe them a deep debt of gratitude, especially to the Ohio State fellows: Abby, Claire, Ashley, Doug, Joshua, Lindsey, Katie, Julie L., Julie S., John, Leanna, Elizabeth, Kathleen, and Jaden; along with Greg Hitzhusen, our faculty sponsor, and Gabe Karns, who often graced our meetings. My gratitude also to Rolf Bouma, the coordinator of the Fellows Program, for many constructive conversations at retreats, and to Fred Van Dyke, the former director of the Au Sable Institute, for always making me feel welcome. The other is the Christian Graduate Student Alliance, which has consistently challenged me to more honest faith and scholarship. Thanks are especially due to Austin Knuppe and to Rob Vandenberg for much discussion and encouragement. I was never actually part of the Society for Ecological Restoration at OSU, but I’ve benefitted from friendships with many of its members. Thank you for taking me on bird walks and winter hikes that all turned into tree identification sessions, and for encouraging my love of the natural world, even when I was very frustrated with my slow pace of identification. Thanks particularly to Don Radcliffe for taking me birding; to Lewis Lolya for helping me set the gain on my microphones; to Ryan McCarthy for answering all my plant questions, and many more besides; and to Julie Slater for giving me so many great time-management tools, and for offering her porch to help keep me sane during the pandemic. The ideas in Chapter 3 were originally developed in a seminar on ecosystem health facilitated by Jay Martin in 2014. Thanks go to Abigail Tamkin, Jeremy Shechter, Ryan McCarthy, and Alex Fotis for their friendship and insightful discussion. vii Many thanks are due to my committee, who have shepherded me through quite a lot of learning: Stephen Matthews has given me much advice about bird sampling, and always in a very encouraging way. Mary Gardiner opened her lab to me and taught me about insect trapping, even knowing how much I would have to stretch to learn it all. Ryan Winston mentored me through a great deal of this work, particularly as it related to stormwater and to green infrastructure; I know your combination of determination, enthusiasm, and grace has had a big impact on the way I approach my work. Two people are not on my committee for purely technical reasons. Angelika Nelson was the curator of the Borror Laboratory of Bioacoustics at the Ohio State University and a member of my committee until she returned to Germany in 2018.