LTREB Renewal: Drivers of temperate forest carbon storage from canopy closure through successional time

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Forest disturbances, such as clear-cutting and fire, typically lead to large losses of carbon and nutrients from forests and their soils. Virtually all forests in the Eastern US are recovering from such disturbances, whether natural or human-caused. It is, however, not well understood what mechanisms control recovery times of forest carbon and nutrient stocks following disturbance. Also not well known is how plant growth, soil development and climate variation interactively regulate recoveries of carbon and nutrients in aging forests. This project uses long-term experimental plots at the University of Michigan Biological Station (a 110-year-old field station in northern Michigan) to investigate how changes in forests lead to overall carbon capture and storage. Globally, forests remove approximately 1/4 of carbon emissions from fossil fuel combustion, with temperate forests, like those studied here, being responsible for almost half of that carbon removal from the atmosphere. However, it is uncertain whether forests will continue to partially offset human-derived carbon emissions as they age and mature following past large-scale disturbances. This project provides critical data and mechanistic understanding needed to predict the magnitude and duration of continued temperate forest carbon uptake, and the ability of forests to provide fiber, fuel, habitat, and many other benefits to society.This long-term (10-year) project began to answer globally significant questions in its productive first 5 years. Researchers are measuring the forests and soils in 6 forest stands (approx. 2 acres each) that were experimentally cut and burned in either 1936, 1948, 1954, 1980, 1998, or 2017. These cutting and burning treatments replicate larger-scale cutting and burning that occurred in the early 1900s across the Great Lakes region within which the experimental stands are nested. Forest structural measurements include patterns of tree, leaf, and branch density and arrangement. Soil measurements include both nutrient distribution and availability and soil carbon fluxes. By using nearby old forests (130- to 200-yr-old) that were not severely cut and burned as reference points, the team is linking disturbance, climate, soil, and vegetation controls to long-term patterns of carbon sequestration in forests that are representative of other forests across the northern U.S. and similar regions in Canada, Europe and Asia.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.