High spatial resolution remote sensing models for landscape-scale CO₂ exchange in the Canadian Arctic

ABSTRACT

Climate warming is affecting terrestrial ecosystems in the Canadian Arctic, potentially altering the carbon balance of the landscape and contributing additional CO₂ to the atmosphere. High spatial resolution remote sensing data can enhance models of net ecosystem exchange (NEE) and its component fluxes, gross ecosystem exchange (GEE), and ecosystem respiration (ER) by quantifying vegetation structure and function over time. In this study, we explored the variability of daytime CO₂ exchange rates for three vegetation types along a natural moisture gradient at ecologically distinct mid- and high Arctic sites. We demonstrated that for the two sites studied, there was no statistically significant variation in CO₂ exchange rates for the vegetation types through the peak growing season. Hence, the capacity to model these rates with a limited number of satellite data acquisitions is feasible. Simple bivariate models relating the Normalized Difference Vegetation Index (NDVI) to CO₂ exchange processes (GEE, ER, and NEE) were developed independent of vegetation type and geographic location and validated using independent data. The spectral models explain between 33 and 94 percent of the variation in CO₂ exchange rates at each site, indicating a high level of functional convergence in ecosystem-level structure and function within Arctic landscapes.

KEYWORDS:

• Carbon dioxide exchange
• net ecosystem exchange (NEE)
• normalized difference vegetation index (NDVI)
• Arctic

Acknowledgments

The authors thank Kimberly Molina, Dana McDonald, Eva Fisher, and Shanley Thompson for their assistance collecting field data. Special thanks to Dr. Paul Grogan for his advice related to CO₂ sampling and chamber design. Thank you to Dr. Scott Lamoureux, director of the Cape Bounty Arctic Watershed Observatory (CBAWO), for his guidance.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Polar Continental Shelf Program with travel assistance received from the Department of Indian Affairs and Northern Development and the Northern Scientific Training Program. Funding was provided by the Natural Sciences and Engineering Research Council of Canada (NSERC) in the form of Postgraduate Doctoral Scholarship to David Atkinson and a Discovery Grant (No. 388581) to Dr. Paul Treitz.