Research

We’re interested in biotic interactions in the face of climate change and extinction, and work across spatial and temporal scales, and in a range of systems. Note: I’m in the process of designing a new website, which includes details about my students’ work. In the meantime, feel free to read more about our projects here.

A modern megaherbivore: Bison bison at Konza Prairie, blithely disregarding the grazing experimental design.

What were the ecological consequences of the end-Pleistocene megafaunal extinctions?

While the causes of the North American megafauanal extinctions have been the source of extensive debate, the ecological consequences of theose extinction have received less attention. My research suggests that the late-glacial collapse of native megaherbivores may have contributed to novel plant associations by releasing deciduous trees from herbivory and altering fire regimes follow the build-up of forest fuels (Gill et al., 2009; 2012).

Are North American trees with megafauna fruits dispersal limited?

PhD student Ben Seliger is investigating the link between dispersal mechanism and range filling, the ratio of the observed range to the range predicted from species distribution models. We’re particularly interested in testing the Janzen and Martin hypothesis — the idea that trees that produce fruits thought to be dispersed by long-extinct megaherbivores. Testing whether modern trees are in equilibrium with climate can help inform which species are good candidates for managed relocation, and whether rewilding can be a useful tool in the conservation of trees such as endangered Torreya taxifolia.

How sensitive is a terrestrial-marine linkage that provides critical supporting services to native biodiversity to global change?

The Falkland Islands are a biodiversity hotspot in the South Atlantic, home to critical breeding habits for penguins, other seabirds, and marine mammals. These animals are an important source of nutrients for native tussac grasses, which in turn provide shelter from persistent westerly winds. PhD and A2C2 IGERT student Dulcinea Groff is researching the impacts of abrupt climate change, anthropogenic changes in fire regimes, and non-native sheep grazing to this terrestrial-marine linkage, using the sediment record. We’ve partnered with the South Atlantic Environmental Research Institute and Falklands Conservation to provide a paleoecological context to the modern conservation of these beautiful islands and their important biota. You can read more about Dulcinea’s work at our Experiment.com crowd-funding page.

How did the warrah get to the Falklands?

The Falkland Islands wolf, or “warrah,” was the first carnivore to go extinct in the historical record, due to overhunting by European sheep herders in the 19th century. It was also the only native mammal on the islands, and its origins have long been contested; to date, there is no definitive evidence as to whether people visited the Falklands before European arrival in the 18th century. MS student Kit Hamley is investigating the islands for evidence of prehistoric human activity using the charcoal and archaeological record, and is analyzing warrah fossils. By nailing down when and how the Falklands arrived, we can better understand how native biota (including a number of species of ground-nesting seabirds) were affected by global change.

How have bison been affected by abrupt climate change? 

Bison are one of the few species of megafauna to survive the Pleistocene extinctions, and have played an important role in maintaining the biodiversity of prairies during the Holocene. PhD and A2C2 IGERT student Jeff Martin is using the fossil record to test how bison body sizes have been influenced by abrupt climate change, with an eye on helping the bison industry and conservationists prepare for the coming centuries of climate change. We’re also interested in the ecosystem services that bison provide, and how Holocene climate changes and bison’s near-extirpation from North America has affected native vegetation.

Additionally, I’ve got projects on on the impacts of the mid-Holocene hemlock decline on aquatic communities, the response of the New England boreal forest to abrupt warming following the end of the last ice age, origins of New England alpine refugia, novel communities and ecosystems, paleo-invasions, and the impacts of Pleistocene megafaunal extinctions on vegetation and small mammal communities at Rancho the La Brea.