Research Overview
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Motivation
We currently live in a time of rapid global change: climate, land use/cover and disturbance regimes are dramatically shifting, largely due to various human activities. Consequently, we are also in the middle of the Earth's sixth mass extinction event - the first in 65 million years (end of the dinosaurs). My personal mission is to 1) study how biodiversity and ecosystems respond to different aspects of global change and 2) study the capacity of biodiversity and ecosystems to keep up. I work across terrestrial and aquatic realms and across spatial scales from individual ecosystems to landscapes to continents. |
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Wildfire effects on lake ecosystems
As wildfire activity has increased throughout much of the US over recent decades, thousands of lakes and reservoirs (hereafter, lakes) have experienced watershed wildfires and may therefore suffer declines in drinking water quality or recreational value. Despite this, there has been relatively little research on the effects of wildfires on lakes; what we know generally comes from a small number of Canadian studies or from stream and river research. Therefore, we urgently need research more lake-fire research across more ecologically diverse regions, particularly in fire-prone or heavily populated regions. Currently, my colleagues and I are studying the effects of the 2021 Greenwood Fire on lakes in Superior National Forest, Minnesota. Specifically, we targeted lakes ranging from minimally burned watersheds to completely burned watersheds and are tracking how lakes respond throughout the ice-free season (i.e., from May snowmelt to the onset of fall in September). We were fortunate to obtain a RAPID grant from the US National Science Foundation for this research (awards 2212082 and 2212083). I have also recently collaborated with the Lake County Water Resources Department to study the response of Clear Lake, California to the record-setting 2018 Mendocino Complex Fire, which burned 40% of the Clear Lake watershed. Clear Lake is the largest naturally formed lake in California (besides Lake Tahoe, which is shared with Nevada) and supplies drinking water for 40,000 people, many of whom are economically disadvantaged or members of local Tribes. In this project, we took advantage of over 50 years of phosphorus data, a key limiting nutrient for primary productivity. Interestingly, long-term climate warming over the last 50+ years is a bigger driver of phosphorus increases (i.e., "eutrophication") than episodic wildfires. |
Burned shoreline of the McDougal Lakes from the 2021 Greenwood Fire in Superior National Forest, Minnesota (photo: June 2022)
Here is the story of how a hike through the charred woods in Lassen National Park, CA inspired my interest in lakes and fires, leading to an award-winning review paper: "Do lakes feel the burn?"
McCullough et al. (2019); Global Change Biology. |
Climate, connectivity and conservation
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Landscape connectivity is essential for facilitating important ecological processes (e.g., finding food or mates, migrations). In other words, biodiversity needs to move among different habitats to survive. However, humans keep making this harder by converting land, fragmenting habitats and altering the Earth's climate.
Currently, I am investigating relationships between freshwater habitat corridors (i.e., networks of lakes and streams/rivers) and protected areas across the US using the same methods used to map corridors on land. Interestingly, most freshwater networks only span 5-6 km north-south, indicating that relatively few, large networks are important for large-scale connectivity, but these tend to be heavily dammed. Moreover, freshwater networks are poorly represented in protected areas, which are typically designed for terrestrial biodiversity and ecosystems. Although designating vast new protected areas and large-scale dam removal may be impractical, an efficient conservation strategy for maintaining intact freshwater corridors may be to focus on "hub lakes". These lakes are like hubs within human transportation systems: most routes go through these lakes. Therefore, maintaining connectivity at and around these hubs can disproportionately benefit freshwater networks and therefore help maintain corridors for freshwater biodiversity. |
Maintaining freshwater connectivity at hub lakes such as Slate Lake, Minnesota can disproportionately benefit freshwater corridors and biodiversity across larger areas.
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