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Forest and atmosphere dynamics

Monday, July 9, 2012, by Alexander Kappel and Paul Quackenbush
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Long-term scientific research estimates that northern mid-latitude forests, like the Harvard Forest, store nearly a quarter of the billions of tons of CO2 added to the atmosphere annually by fossil fuel burning ( These forests provide an invaluable resource in reducing the amount of greenhouse gases in the atmosphere and slowing climate change. However, the mechanisms behind carbon sequestration in these forests require more investigation in order to begin to predict how these forests might continue to take in carbon over the coming years with increasing amounts of CO2 in the atmosphere. This summer, we, Alex Kappel, a rising senior studying Environmental Science at Clark University, and Paul Quackenbush, a rising junior studying Geography and Environmental Studies at Middlebury College, are working as a team to investigate these mechanisms by researching the post-disturbance dynamics of carbon, water, and energy fluxes between the forest and atmosphere. 

Our study site is a former spruce plantation that was harvested in 2008 and is now an exciting, dynamic setting for plant growth and competition as new vegetation battles for control of resources. Working under the guidance and support of our mentor Chris Williams and his lab group at Clark University, we are gaining many insights regarding science and the natural world, field and lab techniques, and the professional world. 

In order to conduct our research, we have been given the opportunity to learn how to use really impressive equipment. Our most heavily used instrument, the LI-6400XT Portable Photosynthesis System, uses Infra-Red Gas Analyzer (IRGA) technology to measure photosynthesis rates by controlling light, temperature, and carbon dioxide levels in a chamber that we clamp over live leaves. By monitoring the photosynthetic capacity of various species throughout the summer, we can acquire an understanding of how the forest is growing back and how these plants respond to different seasonal and climactic variables. When paired with measurements from a carbon flux tower located on our site, these measurements help us to understand how and why our clear-cut site is transitioning from a net source of carbon to a net carbon sink. 

In addition, we are also using a LI-6200 to measure soil respiration, and a LI-3100 Surface Area Meter which we use to measure the surface area of leaves we collect. By separately measuring many components of the forest that are exchanging carbon with the atmosphere, including leaf photosynthesis and respiration, stem respiration, and soil respiration, we can determine who contributes what to the total CO2 flux between the forest and the atmosphere, as measured by the carbon flux tower. Not many undergraduates are given the opportunity and responsibility to be trained and work with such high caliber, expensive equipment! 


While we are putting in a lot of hard work wading through the ripping and snagging clutches of chest-deep blackberry bushes under the summer sun, we both consider this is one of the best and most rewarding summer experiences of our lives. Between our daily off-roading adventure through the woods to get to our study site and the consistent opportunity to observe such a beautiful setting, this summer is one of learning and appreciation when it comes to the outdoors.