The laboratory’s research program seeks to answer fundamental questions within two broad areas:

(1) What are the patterns and drivers of climatic and environmental change over long- and short-timescales?

(2) How has the natural environment constrained/provided opportunities for cultural and biological change, and how have humans impacted the natural environment?

Answers to these questions are important because they provide a long-term context to help us better understand the nature of current climate change and the role that humans have played in driving it. How unprecedented is its rate? How are ecosystems and people going to respond to it? These are questions that can only be addressed through a long-term, historical perspective, using multiple lines of evidence drawn from the geological, ecological, and archaeological sciences.

In our laboratory, we take a highly inter-disciplinary field- and laboratory-based approach to solving these problems. Out data collection is focused on wetland sediment samples which preserve evidence of climate and environmental changes spanning thousands and even tens of thousands of years. The main analytical techniques we employ include micropaleontology (e.g., pollen, foraminifera), sedimentology (e.g., particle size and shape), and geochemistry (e.g., XRF core scanning, magnetic susceptibility) as proxy indicators of past climates and environments. In addition, laboratory members are also using tree rings to study ecological and climatic questions through an analysis of tree ring widths and tree ages.

The following projects are currently being undertaken by members of the laboratory:

1)Flooded caves, ancient climate, and extinct mammals: a collaborative project in Matanazas, Cuba

Flooded caves and sinkholes offer enormous potential as repositories of information on past climates and ecosystems. With collaborators and support from the National Geographic Society, the Cuban Museum of Natural History, the University of Miami, and elsewhere, lab members are involved in a project examining the relationship between climate, ancient people, and extinct sloths in a cave in western Cuba. The fossilized remains of three sloths were recently identified and recovered from the cave along with sediment and water samples. Sloths went extinct in the Caribbean around 4000 years ago, not long after the arrival of humans, and our research—which will involve the dating and isotopic analysis of the bones, along with the micropaleontological analysis of the cave sediments—will help us better understand the nature of prehistoric extinctions and the degree to which humans caused them. In addition, our sediment analysis research, which will focus on reconstructing the flooding history of the cave, will provide information on how underground freshwater resources may be impacted by climate change in the future.

2)High-resolution records of climate change and hurricane impacts from coastal Cuba

Coastal sediments are being studied from multiple sites around Cuba to better constrain patterns of Holocene climate change and identify how hurricane frequency varied in the past. With colleagues at McMaster University and the Coastal Ecosystem Research Center, Gregory et al. (2015) documented the onset of progressively drier climatic conditions during the late Holocene caused by changes in atmospheric circulation using data derived from high-resolution XRF core scanning and benthic foraminifera assemblages. At a site in eastern Cuba, Peros et al. (2015) used particle-size analysis to identify several periods of more frequent hurricanes during the late Holocene, providing important new information about the factors influencing hurricane activity in the Caribbean and also hurricane return-period. For her thesis, M.Sc. candidate Anna Agosta G’Meiner is studying the sediments preserved in Cenote Jennifer, a flooded sinkhole located on the island of Cayo Coco, off the coast of north-central Cuba. The Cenote Jennifer core provides a continuous ~9000 year laminated record that ought to yield one of the best-dated sequences of Holocene environmental change from the Caribbean to date. The sediments are being studied for pollen and charcoal (to reconstruct regional vegetation and fire history), elemental composition, and other proxies, to document the environmental history of the island and determine the origin of the laminations. The findings from this work illustrate the vast potential of sinkholes as archives of high-resolution environmental information. 

Close-up of the Cenote Jennifer sediment core. The white layers represent calcium carbonate-dominated sediment.

Sediment coring at Cenote Jennifer, June 2014

3) 20th- century impacts on vegetation in southern Québec: evidence from tree rings and paleoecology

Using tree rings, pollen, and charcoal analysis, laboratory members have been examining questions related to the response of vegetation to recent climate change and human activities. One important site of research is the Johnville Peat Bog, a unique ecosystem in southern Québec that supports a sub-Arctic type vegetation community. Research by undergraduates Jennifer Ward, Jamie Carroll, Andrew Manouk, and Julien Vachon has shown that historic landuse changes affected the bog environment as early as AD 1800, when the region was first settled by people of European origin. Since that time there have been further impacts, including the drainage of the bog in the mid-20th century, which appears to have led to the expansion of black spruce trees across the site. The work of these students is important as it provides valuable environmental baseline data to inform ongoing restoration efforts at the bog. Elsewhere in southern Québec, M.Sc. candidate Benjamin Marquis has been studying the response of sugar maple and yellow birch trees to recent climate change using tree rings. Specifically, his work addresses whether trees at their range limits are more sensitive to climate than trees nearer to the center of their ranges. Undertaking this project at Mont-Mégantic National Park, which provides an excellent altitudinal gradient to test his hypotheses, Benjamin’s research will be important for informing us about how these tree species will respond to climate change under future global warming scenarios.

Collecting tree cores at the Johnville Peat Bog, summer 2013.

View of the Johnville Peat Bog, to the north, fall 2014. Elevation is approximately 100 m and image was taken with the Phantom 2 Vision+ drone.