Learn more about the recipients of Arboretum Research Fellowships:

2021 Research Fellows


Roberto Carrera-Martínez

Department of Integrative Biology
Advisor: Sean Schoville

Exploring the distribution of invasive earthworms and exotic plants and indirect interactions: Indications of invasional meltdown or disturbance-mediated establishment?

Earthworm invasions in the north-central region of North America have considerable negative effects on most of the basic ecosystem functions. These invasions are dominated by the jumping worms (Amynthas agrestis–complex) and the European lumbricids. Some studies have suggested that these invasive earthworms may be facilitating the invasion by exotic, non-native plants, like buckthorn (Rhamnus catharica) and honeysuckles (e. g. Lonicera x bella). However, recent studies have reported neither facilitation nor mutually beneficial interactions between these invasive species. These results depend on field-based studies, which may overlook species-specific interactions (as earthworm species composition is not usually documented) and indirect interactions. Earthworm and plant invaders are known to positively respond to human disturbance and infrastructure, yet very few studies have tested whether this may explain field correlations between the invasive species. The UW–Madison Arboretum has a proud legacy of research on invasive earthworms and plants, with foundational data on the distribution of invasive species providing a unique opportunity to disentangle the ecological mechanisms underlying invasive species interactions. The purpose of this proposal is to study the interaction between anthropogenic disturbance due to infrastructure (i.e., trails, roads) and the (co-) distribution of the invasive earthworms and plants. We propose to combine field surveys and mesocosm experiments, while also conducting taxonomic and genetic work to identify earthworm species more precisely. Field surveys will include randomized sampling on a grid as well as targeted sampling of plant-invaded sites, in relation to a distance gradient from disturbed sites created by infrastructure within the UW–Madison Arboretum property. The earthworm species that shows the strongest correlation with the invasive plants will then be used in a mesocosm experiment to explore earthworms’ effect in the competition between native and invasive plants. This represents a unique opportunity to study invasions while taking into consideration time since establishment and management practices.

Roberto began his PhD in integrative biology at UW–Madison in 2020. He received his MS in forestry from University of Georgia in 2018 and BS in biology from University of Puerto Rico in 2016.

Research statement:

My interests in studying earthworms started during my first Research Experiences for Undergraduates opportunity in 2013. Back then, I did not know anything about earthworms, not even that they could be invasive species, It was extremely shocking to me that there were so many unanswered questions about these incredibly humble creatures.

I was also shocked by how little people knew about my home, as some students and faculty (either at scientific meetings or on campus) were unaware that Puerto Rico is a U.S. territory and that we are U.S. citizens, or knew of our colonial history. Furthermore, many colleagues ignored the social issues that I felt and endured as a minority in the U.S., and some even openly questioned my abilities as a scientist because of my ethnicity. While this was daunting, especially in this formative stage in my career, I’ve since recognized that I can be a positive agent of change at institutions in the U.S. by helping to prepare other students to confront such challenges.

Mary-Claire Glasenhardt

Nelson Institute for Environmental Studies
Advisor: Paul Zedler

Community dynamics of an 86-year-old tallgrass prairie restoration: Curtis Prairie’s current conditions, temporal change, and land management

Monitoring is a necessity in a time of climate change. Curtis Prairie is an ideal site to conduct monitoring as an early tallgrass prairie restoration with a history of vegetation surveys. Long-term monitoring is critically important to understand how ecosystems are changing over time, identify factors driving these changes, and enable evidence-based management decisions. As primary outputs, my resurvey of Curtis Prairie will: 1) create a quantitative picture of the current vegetation community, and 2) identify how diversity and distribution have changed over time at the site and species level. Additionally, I will look at the relationships between 1) vegetation and functional traits associated with ecosystem function, 2) species diversity on invasion resistance, 3) invasive species cover on species richness, and 4) effects of disturbance caused by management on diversity. Identified patterns in succession, invasion resistance, or management techniques that reduce invasive species or increase diversity, would benefit other tallgrass prairie restoration efforts.

Mary-Claire began her MS in environment and resources at UW–Madison in 2020. She received a BS in environmental science from University of Notre Dame in 2002.

Research statement:

I not only want to track changes over time in our natural areas and ascertain what the data indicates, but also to generate interest in our native plants through visitors and volunteers as well as initiate community actions which broaden native species usage to become the common sub/urban landscape.

Ultimately, I want to see proactive management of our natural resources and comprehensive, connected greenspaces. I hope this will help bring back the imperiled tallgrass/savanna complex and, as a result, the dwindling wildlife that depend upon it.

Dana Johnson

Department of Soil Science
Advisor: Thea Whitman

Impact of non-native Amynthas spp. on soil structure, fungal biomass, and fungal diversity in forest soils

Invasive soil mesofauna affect all aspects of forest ecosystems from aboveground plant communities to soil structure. Soil is an important, yet hidden, part of forest ecosystems and comprises chemical, physical, and biological components. The physical structure of soil allows water to infiltrate and drain, facilitates gas exchange, provides space for root growth, and acts as habitat for micro- and meso-organisms such as fungi and earthworms. Within the soil, fungi move along soil aggregates and through pores in search of water and nutrients. Mycorrhizal fungi create symbiotic relationships with plants and trade water and nutrients for simple carbon molecules derived from plant photosynthesis. Fungi have also been shown to create macroaggregates (>250 μm in diameter), which improve soil structure. The arrival of invasive soil mesofauna may affect soil structure and fungal communities. Amynthas spp., also known as “jumping worms,” are native to southeast Asia and were first discovered in the UW–Madison Arboretum in 2013. Amynthas spp. consume forest soil organic matter at faster rates than the more common and widespread nonnative earthworm Lumbricus terrestris. The effect of Amynthas spp. on fungal biomass and diversity in Wisconsin forests has not yet been widely studied. I propose an in situ paired mesocosm experiment to analyze the effect of Amynthas spp. on soil aggregation and fungi diversity and biomass. This research will increase our understanding of the ongoing species invasion and inform land management and restoration decisions at the Arboretum.

Dana began her MS in agroecology at UW–Madison in 2018. She received a BA of in earth and planetary sciences from Northwestern University in 2016.

Research statement:

Moving from Iowa to Paraguay to Wisconsin has been a physical and mental journey for me. Over the past year and a half, my view of sustainability, agriculture, and the relationship of humans to ecosystems has been profoundly changed. Today when I walk across the farmland on which I grew up, I see it differently. I see soil teeming with micro- and macroscopic life. I see lost species and potential.

Building a relationship between land and people – an important part of Aldo Leopold’s land ethic – requires us to stand still and see the natural world. We must put our hands in the soil, feel the grasses against our legs, and run our fingers over a tree. Rebuilding a connection to the land can start with youth education. It is all too easy to walk on a sidewalk or through the woods and not notice the soil beneath our feet. I hope to use my research and previous teaching experiences to build activities that allow students to experience – see, touch, smell – soil.

I believe that as a scientist I can use my research and passion for discovery to foster curiosity and scientific literacy in the next generation of scientists and critical thinkers.

2020 Research Fellows


Katherine Charton
Department of Integrative Biology
Advisor: Ellen Damschen
Effects of management and precipitation on woody encroachment in tallgrass prairie

In an era of rapidly changing climatic conditions, anticipating the rate and extent of ecosystem change will help inform conservation priorities and adaptation efforts. Tipping points largely determine the rate at which changes in ecosystem components, including biodiversity and ecosystem services, occur, and they can result from seemingly small changes in environmental variables. Woody encroachment is one such globally occurring change thought to create tipping points reinforced by positive feedbacks and considered irreversible past certain critical thresholds. Managing these ecological thresholds in order to prevent unwanted encroachment and intervene before communities transition to an alternative stable state requires an understanding of the multiple environmental variables, and their interactions, that drive state change.

This project will examine the effects of management, climate change, and their interaction on woody invaders in tallgrass prairies. Specifically, through field work at Arboretum, outlying, and non-Arboretum properties, I will ask how established woody plants respond to the interaction of management and precipitation across a gradient of tallgrass prairie habitats and if recruitment success of woody plants differs under variable management and precipitation conditions. Results will be highly relevant to the conservation and restoration of prairie communities and to our basic understanding of disturbance and community stability. Integration with subsequent research may also provide insight into the utility of plant functional traits in determining competition outcomes between prairie and woody plants, the role of positive feedbacks in woody plant dispersal and colonization into grasslands, and the differences in ecosystem function under competing stable states as prairies move from grassland to wooded systems.

Katherine began her Doctor of Philosophy in Integrative Biology at UW–Madison in 2019. She received a Bachelor of Science in Conservation and Resources Studies from University of California, Berkeley in 2017.

“Scientists have the platform to profoundly empower people and communities to become advocates for their land through sound science.”


Erin Crone
Department of Forest and Wildlife Ecology
Advisor: Dan Preston
Ecology of urban herpetofauna in Madison, Wisconsin

Urban herpetofauna face many challenges to survival and reproduction. The proposed research will investigate two common urban threats to herpetofauna: stormwater pollutants and invasive species. Urban stormwater contains various pollutants that have been known to harm amphibian larval development. Previous research suggests amphibian taxa differ greatly in tolerance of stormwater pollutants. We seek to explain observed patterns in occurrence and distribution of amphibians around Madison, Wisconsin, by testing larval tolerance to stormwater ponds. Our research will use laboratory trials to compare survival and growth of six species of local amphibian larvae when exposed to stormwater pond sediments. Additionally, we plan to address a knowledge gap in community ecology regarding native urban predator responses to novel invasive prey. Little is known about the role of invasive Asian jumping worms (Amynthas spp.) in natural food webs and whether native predators potentially contribute to biocontrol. Our research will examine diet composition of four terrestrial amphibian and reptile predators in and around the UW–Madison Arboretum via nonlethal stomach contents sampling. We will quantify effects of jumping worms on herpetofaunal diets by comparing prey consumption in sites with and without jumping worms. We hope studying widespread threats to urban herpetofauna will provide information to support management for herpetofauna habitat.

Erin began her Master of Science in Wildlife Ecology at UW–Madison in 2019. She received her Bachelor of Science in Environmental Science from Bellarmine University in 2018.

“I believe that promoting urban coexistence with wildlife and creating natural habitats within urban areas is vitally important in our rapidly developing world, both for the persistence of species and to encourage appreciation for ecology within urban communities.”

Anna Skye Harnsberger
Department of Entomology
Advisors: Claudio Gratton and Karen Oberhauser
Effects of local and landscape characteristics on native prairie butterfly communities

The dispersal abilities of butterflies might affect the degree to which they are affected by landscape heterogeneity, habitat patchiness, and isolation. The abundance of very mobile butterflies at a site could be determined by landscape characteristics, especially if the butterflies have a metapopulation structure or are migratory. Less mobile butterflies might be more affected by local characteristics. My experience studying monarchs on Arboretum land and throughout Wisconsin has given me the skills to assess native floral communities, evaluate pertinent landscape metrics, and interpret their relationships to butterfly abundance. I aim to apply these skills to assess butterfly diversity and abundance at Arboretum sites containing native prairie, as well as other sites in southern Wisconsin, and relate these metrics to butterfly life histories and site and landscape characteristics. Butterfly community surveys on Arboretum lands will add to current efforts to assess biodiversity.

Skye began her Master of Science in Entomology at UW–Madison in 2018. She received a Bachelor of Arts in Biology from Occidental College in 2016.

“We have a moral responsibility to document and conserve native insect species on some of the last remaining tallgrass prairies and new restorations that humans are putting in place. We also have a moral responsibility to do restorations correctly and evaluate our success in supporting insect habitat.”

Nick Hoffman
Nelson Institute for Environmental Studies
Advisor: Sara Hotchkiss
Stormwater history: A fifty-year reconstruction of the runoff-mediated disturbance load to Curtis Pond and Curtis Prairie

The restoration of Curtis Prairie depends, among other things, on managing its vegetative response to the salts, nutrients, and pollutants to which it is subjected. Likely, the major source of these disturbance loads is the surface water dynamics associated with the outflow of water from Curtis Pond and Coyote Pond, which receive large annual influxes of stormwater from sewersheds encompassing the Madison Beltine highway and residential developments. We propose to collect sediment cores from Curtis Pond and Coyote Pond in order to reconstruct the loading of salts, nutrients (N,P,S), and pollutants (PAHs, microplastics, and an ensemble of metals) into these ponds over the past fifty years. We will also collect a set of soil samples along transects down-gradient of the pond to understand how these pollutant loads have migrated with surface water into the prairie over the past fifty years. Knowledge of the magnitude of these disturbance depositions and their spread into the prairie will provide context for the historical response of Curtis Prairie’s vegetation to reed canary grass invasion and other ecological changes.

Nick began his Master of Science in Environment and Resources at UW–Madison in 2019. He received a Bachelor of Science in Earth and Atmospheric Sciences from Massachusetts Institute of Technology (MIT) in 2018.

“Ecology means studying the household. Ecological management then can be considered housework. . . . I simply want to help with this housework.”

Carson Keller
Department of Zoology
Advisor: John Orrock
Do invasive species modify small mammal trophic interactions and generate predictable behavioral changes?

Invasive species dramatically alter ecosystems through the creation of novel habitat, competition and consumption of native species, and generating reductions in biodiversity. Currently, there is limited understanding of how invasive species mediate ecological interactions and generate indirect effects; this limits our ability to predict their impacts on native species and the factors leading to invasion success or failure. In particular, evaluating the effect of invasive species on plant-herbivore and predator-prey interactions are vital, as changes in these relationships alter plant and animal species distribution, abundance, and behaviors.

Recent work has demonstrated that individual behavioral traits can be a primary mechanism driving differences in ecological interactions within invaded and uninvaded habitats. However, focusing on singular behaviors ignores mounting evidence that animals exhibit correlated suites of behaviors called behavioral syndromes or “animal personalities.” Correlated behaviors (e.g., boldness and neophilia) may facilitate differences in the exploitation or avoidance of invaded habitats, potentially redefining the existing ecological interactions in the context of rapid environmental change. For instance, bold neophilic individuals may exploit invaded areas more quickly, modifying trophic interactions through changes in consumer pressure on native species, ultimately shifting species distribution, abundance, and behaviors.

Using two invasive species, buckthorn (Rhamnus cathartica) and jumping worms (Amynthas spp), I will evaluate: 1) if predictable suites of behaviors characterize the animals within invaded and uninvaded habitats, and 2) if these behaviors generate variation in rodent-worm interactions that promote biotic resistance or invasional meltdown. I use experimental site-level manipulation of buckthorn and sites along a gradient of Amynthas-invaded habitat within the UW Arboretum. Trophic interactions will be quantified by measuring small mammal foraging of native and invasive species. I will measure behaviors essential for individual survival and fitness, such as habitat selection, activity timing, boldness, stress physiology, and anti-predator behaviors. Activity timing and foraging will be measured using camera trap boxes and live trapping followed by behavioral assays to determine individual and population level distribution of personalities. If predictable suites of animal behaviors exist across different types of biological invasions, this may help us better understand how ecosystems and the organisms within them may respond to future invasions. Determining how invasions alter ecological interactions will allow for informed management efforts that have direct local and global impacts on the restoration and conservation of native species.

Carson began his Doctor of Philosophy in Zoology at UW–Madison in 2019. He received a Master of Science in Biology from California State University, Northridge, in 2018 and a Bachelor of Science in Ecology, Evolution, and Organismal Biology from California State University, Fresno, in 2013.

“I believe that some of the most effective management and conservation strategies are derived from not only research but from the investment and fostering of community engagement. As an instructor and researcher, it has always been my priority to make science understandable, accessible, and engaging in order to spark student and public interest.”