Counting Carbon: Quantifying Biomass in the McMurdo Dry Valleys through Orbital & Field Observations

We use correlative field studies and high-resolution multispectral remote sensing data from the WorldView-2 instrument to estimate the abundance of photosynthetically active biomass (photoautotrophs consisting primarily of microbial mats and mosses) in Canada Stream in Taylor Valley, McMurdo Dry Valleys (MDV), Antarctica. In situ field investigations were performed to (1) acquire ground validation targets for atmospherically correcting satellite imagery, (2) derive spectra of “pure” geologic and biological endmembers, (3) estimate photoautotroph cover from remote sensing data, and (4) convert these coverage estimates to biomass using data collected in the field. Our results suggest that, on the morning of 12 December 2018, the Canada Stream system contained more than 3,800 kg of photosynthetically active carbon. Extrapolating our unmixing results to the entirety of the Fryxell basin of Taylor Valley, Antarctica, we model the presence of more than 750,000 kg of photosynthetically active carbon across the landscape and carbon fixation rates roughly equivalent to five hectares of tropical rainforest. The ability to spatially and temporally quantify the amount of photosynthetically active biomass using remote sensing data in the MDV of Antarctica is a revolutionary development that will help elucidate the ecological drivers and environmental responses in this cold desert landscape.