Photo: Alex Tran Photography
Current Research
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My PhD research is part of the NSF funded Water Sustainability and Climate in the Yahara Watershed project at the University of Wisconsin-Madison, where I focus on urban ecosystem services. I combine synthesis, observational, and experimental studies to explore questions related to how landscape structure, land-use history, and biodiversity influence urban ES provision. Listen to a 30min radio interview about my dissertation work, here.
Why Urban Ecosystem Services? There are many great reasons to study cities – not least of which is that by 2050, up to 75% of people globally will live in one! Yet despite the potential ramifications of this urbanization for ecosystem services, and the importance of locally produced services for the health and wellbeing of urban residents, studies of ecosystem services in urban areas remain rare. Here in the Yahara watershed, almost 25% of the land is developed – so improving the sustainability of the landscape requires an understanding of the urban areas within it. |
Watch a 60 sec "Pop Talk" about my urban ecology work from #ComSciCon 2015
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The biodiversity-ecosystem service relationship in urban areas
Urban ecosystem services (ES) affect the health and wellbeing of over 3.5 billion people who live in cities. However, syntheses addressing ES provision rarely include urban areas. I conducted the first quantitative review focused explicitly on the ecology of urban ES, including the role of biodiversity in service provision. I found that studies typically measure only a single service in one city, precluding assessment of ES synergies, tradeoffs, and cross-city comparisons. I also found that while most studies attribute ES provision to a habitat or land-use type, studies that consider biodiversity-ES relationships are more likely to recognize a specific functional group, community, or population as the key provider of an ES. This work has recently been published in Oikos! See my publications page for access.
Urban ecosystem services (ES) affect the health and wellbeing of over 3.5 billion people who live in cities. However, syntheses addressing ES provision rarely include urban areas. I conducted the first quantitative review focused explicitly on the ecology of urban ES, including the role of biodiversity in service provision. I found that studies typically measure only a single service in one city, precluding assessment of ES synergies, tradeoffs, and cross-city comparisons. I also found that while most studies attribute ES provision to a habitat or land-use type, studies that consider biodiversity-ES relationships are more likely to recognize a specific functional group, community, or population as the key provider of an ES. This work has recently been published in Oikos! See my publications page for access.
Soil-based ecosystem services in urban Madison, WI
This chapter of my PhD explores the degree to which current land cover, within-land cover variability, and agricultural legacies influence multiple soil-based regulating services throughout the city of Madison.
In cooperation with numerous local stakeholder organizations and private homeowners, I collected soil samples and vegetation data from 100 sites throughout the City of Madison in the summer of 2015. Sites encompassed 5 land-cover classes (forest, grassland, open space, and both low and medium-density residential areas) and spanned a historical development gradient of ~125 years, representing the transition from agricultural to urban land use. The resultant 1600 soil samples have been analyzed for bulk density, soil carbon, available P, and particle size distribution in order to assess effects of land-cover, within-landcover variability, and land-use legacies on three soil-based urban ecosystem services: carbon storage, water quality regulation, and runoff regulation.
This chapter of my PhD explores the degree to which current land cover, within-land cover variability, and agricultural legacies influence multiple soil-based regulating services throughout the city of Madison.
In cooperation with numerous local stakeholder organizations and private homeowners, I collected soil samples and vegetation data from 100 sites throughout the City of Madison in the summer of 2015. Sites encompassed 5 land-cover classes (forest, grassland, open space, and both low and medium-density residential areas) and spanned a historical development gradient of ~125 years, representing the transition from agricultural to urban land use. The resultant 1600 soil samples have been analyzed for bulk density, soil carbon, available P, and particle size distribution in order to assess effects of land-cover, within-landcover variability, and land-use legacies on three soil-based urban ecosystem services: carbon storage, water quality regulation, and runoff regulation.
Urban forestry and the intra-urban heat island
In this chapter, I continue my work in Madison by investigating the intra-urban heat island. We have developed a custom-built, bicycle-driven mobile temperature sensor to conduct this work (pictured at left). Using this custom sensor, I can ask questions about how impervious surfaces and canopy cover interact to influence temperature regulation services at a local scale (for example, do only large forested areas cool off the city, or can street trees fill this role, too? How much added benefit do trees give compared to grass?). Ultimately, this data can help us understand how current decisions regarding urban forest policies may determine future ecosystem service provision.
This work is supported through a Zone IV Fellowship in Urban Forestry, through the Garden Club of America and Casey Trees
In this chapter, I continue my work in Madison by investigating the intra-urban heat island. We have developed a custom-built, bicycle-driven mobile temperature sensor to conduct this work (pictured at left). Using this custom sensor, I can ask questions about how impervious surfaces and canopy cover interact to influence temperature regulation services at a local scale (for example, do only large forested areas cool off the city, or can street trees fill this role, too? How much added benefit do trees give compared to grass?). Ultimately, this data can help us understand how current decisions regarding urban forest policies may determine future ecosystem service provision.
This work is supported through a Zone IV Fellowship in Urban Forestry, through the Garden Club of America and Casey Trees
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Invasive species interactions and the Asian Jumping Worm
This chapter explores interactions between two invasive species in Wisconsin's Yahara region. The Asian jumping worm, discovered in Wisconsin in 2013, is a little studied species of earthworm expected to impact forests. Recent work from our lab suggests that through rapid leaf litter consumption, these earthworms create a flush of nutrients that may be susceptible to loss. Buckthorn, a widespread shrub, is a harmful invader in Midwestern US forests, creating dense thickets that reduce carbon storage, impede recreation, and shelter harmful crop pests. In addition to their individual impacts, however, jumping worms and buckthorn may interact such that each species increases the spread of the other. I am conducting field experiments in collaboration with the UW-Madison arboretum to study this interaction, helping researchers and conservationists better understand and prepare for potential consequences of these invasive species. This work is supported through a National Geographic Young Explorer award. |
Check out the Asian jumping worm in action!
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PAST RESEARCH
Forest Fragmentation, Tree Diversity, and Carbon Storage
As part of the Monteregie Connection project, my MSc research used a mixture of satellite data, field-based methods, and allometry to investigate the links between forest fragmentation patterns, tree biodiversity, and carbon storage in a temperate agro-ecosystem in the Monteregie, QC.
This work has been published in Ecosphere and Oecologia. See my publications page for access.
Check out Alex Tran Photography for incredible field photos from the Monteregie Connection project!
Effects of Nutrients and Defoliation on Grassland Ecosystem Function
As part of a Nutrient Network project, my honours thesis used a combination of mini-rhizotron technology and litter bag experiments to investigate the effects of nutrient additions and defoliation on grassland root dynamics, and the consequences for soil carbon, on Vancouver Island, British Columbia.
This work has been published in Ecology. See my publications page for access.
Thanks to the funders of my research
