Carbon Cycling in Canada’s Boreal Forest: Investigating the Role of Vegetation Composition on Net Ecosystem Exchange

Canada’s boreal forest plays an important role in the global carbon (C) cycle, but its C dynamics are being altered by climate change. Shifts in temperature, precipitation, and growing season patterns influence how these ecosystems store and release C. Understanding how different regions of Canada’s boreal forest regulate C and respond to climate variability is essential for predicting the impacts of climate change on these ecosystems. My study examines how vegetation composition influences C cycling by comparing the net ecosystem exchange (NEE) at a Boreal Mixedwood Forest in Ontario, and an Eastern Boreal, Mature Black Spruce Forest in Quebec. Using six years (2004-2009) of eddy covariance (EC) measurements, I analyze seasonal and interannual variability in C fluxes and identify environmental drivers influencing these variations. Preliminary results show that the Mixedwood forest consistently functions as a net C sink (-97.97 ± 35.98 g C m-2 y-1), while the Black Spruce site fluctuates between a small C sink and source (-0.2268 ± 15.18 g C m-2 y-1). Seasonal trends reveal that both sites act as C sources in winter when ecosystem respiration (ER) exceeds gross ecosystem production (GEP), and as C sinks in summer, when GEP surpasses ER. However, C uptake is substantially higher at the Mixedwood site, driven by greater GEP and ER throughout the year. My research provides insights into how forest composition regulates boreal C dynamics and enhances our understanding of how these forests may respond to future climate change, informing sustainable forest management strategies.