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The Roots of the Matter

Tuesday, June 24, 2014, by Marisa
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[A curious cow from the pasture outside our house]

I showed up at Harvard Forest blissfully ignorant of all the possible diseases you can get from tromping around in the forest all day, not to mention with an admittedly cloudy understanding of the day to day realities of ecological research. Three weeks later, my paranoia-induced googling has me well-versed on the signs and symptoms of Lyme disease and Eastern equine encephalitis, and I’ve got a clearer idea of what field research is. It’s trial and error, getting lost in the woods, and too many mosquito bites to count, but it’s also the joy of a new nature sighting, the satisfaction that comes with a polished sampling protocol weeks in the making, and the curiosity that being outside never fails in inspire.

[Ground root and soil subsamples headed for the oven to determine how much of each sample is organic matter]Coming in, I expected that I would be doing the grunt work for a pre-established project, but that couldn’t be further from the truth. Working with my mentor, I’ve been either involved in or in charge of every step of the research process, from combing online databases for background information to refining the nitty gritty details of our research question. I spend the bulk of my time reading about, working with, and getting covered in dirt in pursuit of data on carbon storage in forest soils. An understanding of forest soil carbon dynamics is particularly important in light of the changing climate and increasing levels of atmospheric CO2, as New England forests have the potential to act as carbon sinks and soak up some of the extra carbon being released from sources like industry and fossil fuel combustion. My mentor and I are researching the factors that influence soil carbon content, specifically the percentage of soil carbon contained in roots and the ways in which different tree species affect how soil stores carbon.

[Above: the serrated edge of the steel cylinder used for taking soil cores; below: a soil core extracted from the cylinder][Marisa at one of her field sites, collecting a soil sample]To accomplish this, we’re drilling into the soil across Harvard Forest with a steel cylinder attached to a cordless drill and extracting samples that are then taken to the lab for processing. Each soil core is dried in an oven, sieved, and sorted into its leaf litter, root, and soil components. After that, smaller subsamples of some cores are burned at 1020 Celsius (1868 Fahrenheit) to determine the content of carbon and other elements like nitrogen. The data from all this lab work gets organized into spreadsheets so it can be manipulated and shared with other researchers in the hopes of gaining a better understanding of the role soil plays in carbon cycling. Ideally, this experiment will be repeated in four years to gather data on soil carbon stock changes and the interaction between people and the environment both now and in projected scenarios of climate change.

[The product of an hour of picking roots out of a soil core]

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