This new project focuses on how carbon and nitrogen cycling and resulting greenhouse gas emissions change between the growing season, when plants and scientists are active, and outside of the growing season, when plants are not active and many fewer measurements are collected.

For a long time, it’s been assumed that little biogeochemical activity (decomposition) occurs during the winter in northern ecosystems because of the cold temperatures. However, some research by myself and others have shown that this period can be a key determinant of whether ecosystems are net sources or sinks of greenhouse gases, including carbon dioxide and methane. It’s not yet clear why these emissions are so high, relative to other times of the year.

My project will investigate emissions of these greenhouse gases across several different northern ecosystem types at Siikenava II, Finland, using automated chambers and high frequency greenhouse gas flux measurements and uses modeling and experiments to understand why these emissions occur. This research topic is really important both given how much of the earth experiences a winter season with freezing temperatures, how rapidly winters are warming including the earlier onset of spring, and also how long the winter is in Arctic and Polar ecosystems.

Developing a further understanding of the effects of soil freezing and thawing on greenhouse gas emissions in this project is also important for understanding how now-frozen soils will respond to permafrost thaw as soils that are always frozen shift to becoming seasonally or perennially thawed with increased plant activity.

This five-year project runs from 2020 to 2024.