Evolution of North American Ecosystems over the past 20,000 years

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This research program uses a paleoenvironmental approach to understand climate variability and climate change impacts on terrestrial and freshwater ecosystems. The purpose of the research program is to study the scales and mechanisms of climate variability and to quantify terrestrial and freshwater ecosystem interactions and response to long-term climate variability. The role of human impacts, on a continuum from the first arrival of humans on the continent as the Ice Age was ending, to the introduction of extensive agriculture, the arrival of Europeans and rapid industrialization is a key aspect of the research program Although components of these interactions and processes are studied through various means, in this project the entire period can be studied uniformly and comparably using new data collected for this purpose, but especially through the study of extensive databases of paleoenvironmental data that are rapidly being developed, and to which our lab has made a significant contribution. In the short-term, this is done through four interrelated projects. First, we are developing new paleoclimate reconstructions from Arctic and Boreal sites, to better understand the natural variability of the Arctic and to place current warming in context. This uses the early Holocene (5000-9000 years ago), when the Canadian Arctic was quite warm, as a potential, although imperfect analogue of the future and will study in the detail the Medieval period (another relatively warm time) in comparison to today. As the Arctic is changing due to global warming and regional impacts due to resource extraction are increasing, this study will provide insight into what will be these effects in the coming century. These results are put in a global context by a second project reconstructing climate changes of the past 20000 years in the Northern Hemisphere and the world. By better quantifying past climate variability, it will enable climate scientists to place current climate variability in its proper context. Comparing past climate reconstructions with the output of climate models enables climate modellers to improve their models and be able to better forecast the future. New data from the Gatineau Hills will determine how forests respond to long term climate change, and to disturbances such as fire, extensive logging and agriculture. These results can be used in forest management, as the timescales of our study is decades to centuries as is the impact of current activities. In addition, we are studying how lake ecosystems of the region have varied in the past, in relation to the major climate changes, and also by changes in forest composition and land use. This will help to understand how much the lakes of the area have been impacted by events of the past 150 years. A study of the interactions of humans and the environment over the past 15000 in North America will enable us to better understand the impact of European colonization on the landscape. By studying in more detail the nature of the vegetation before the arrival of Europeans, and determining how Native Americans impacted the environment, and were impacted by climate changes of the past, we can better understand how current activities are changing the global carbon balance, as we need a correct baseline on the nature of the forests before the extensive impacts of the industrial age.