More research highlights from the 2015 AGU Fall Meeting

The 2015 AGU Fall Meeting was filled with many highlights, from R2-D2 to Elon Musk. PLOS Ecology’s own Jens Heggs wrote about these and other highlights earlier this week. This was my fourth trip to San Francisco for the AGU Fall Meeting, and while my personal highlights included serving as a chair and an Outstanding Student Presentation Award (OSPA) judge for the first time, along with presenting some of my own research, I was also quite enthused by the work of many researchers from the terrestrial ecology realm, some of which I wanted to feature here.

Christine Rollinson, a postdoctoral associate in Michael Dietze’s ecological forecasting lab at Boston University gave a talk on her work as part of the PalEON project—an interdisciplinary team of scientists working to reconstruct forest composition, fire regime, and climate in forests across the northeastern United States and Alaska over the past 2000 years. In her talk, entitled “Millennial-scale drivers of carbon storage and flux in terrestrial ecosystem models,” Rollinson presented data from a comparison of ten terrestrial ecosystem models that simulate monthly carbon pools and fluxes from 850 to 2010 CE for six different sites. Interestingly, the main drivers that determined how much carbon there was and where it was moving through time, varied by ecosystem model—often changing depending on the time length or spatial extent of the analysis. “Right now I’m not focusing on trying to get the models to hit a target since the uncertainties around empirical data about carbon storage and flux across the landscape are often very large and/or poorly quantified,” Rollinson said, “instead I am trying to understand why the models don’t even agree on the direction of climate effects on ecosystems at large time scales.” One hypothesis based on this finding is there is poor representation of the interactions of ecosystem components within models. “What I find really interesting and fun about this research is that trying to tease out the cause and effect relationships among climate, biogeography, and the carbon cycle in models can be almost as challenging as it is in actual ecosystems.” By looking backwards to better constrain model estimates, we can strengthen our prediction capabilities for the future. For more on Rollinson’s work you can also visit her website.

Continuing the theme of decreasing our uncertainty in understanding our world, Rodrigo Vargas, Assistant Professor from the University of Delaware, gave an invited talk entitled, “Spatial variability of soil carbon across Mexico and the United States.” Vargas’s research focuses on using a machine learning approach to combine publically available information on soil organic carbon with geographic information (such as digital elevation models) in an effort to make better estimates of soil organic carbon stocks at fine scales. In areas of the world like Mexico, where field data is sparser than the US, this method could provide valuable information for carbon accounting. Vargas has a forthcoming article on the subject in AGU’s EOS.

There was also a lot of interesting work focusing on another outcome for below-ground carbon. Microbes that produce carbon dioxide typically require oxygen–hence the “oxide” part. Carbon dioxodie is two oxygen atoms paired up with one carbon. Methane, however, is a lone carbon atom paired with four hydrogens and is produced by microbes who favor an anoxic environment—meaning no oxygen. Peat lands across the globe produce a lot of methane. An environment that is consistently wet creates an ideal environment for methanogens (microbes that produce methane). Peat forms when dead plant material builds up faster than it can decompose. But whether it is peat or dissolved organics in the water within the peat, which one is the greater source for methane production is up for debate. Alison Hoyt, a graduate student at the Massachusetts Institute of Technology presented work focusing on understanding the advection and diffusion of dissolved gases within peat bogs across the globe in order to better understand methane sources. Her findings indicate that methane emissions are primarily coming from the decomposition of peat, regardless of latitude—an important finding and a consideration moving forward when carbon budgeting for peat lands.

In related research, Alex Cobb, from the Singapore-MIT Alliance for Research and Technology (SMART), presented work focusing on the hydrologic feedback between the depth of the water table and the accumulation of peat in tropical peat lands, with a focus on better explaining the variation in peat accumulation across the tropics. In his work, Cobb showed that being able to scale from local measurements to broad estimates of peat accumulation require coupling topographic data with sampling schemes that consider the dynamics of “peat domes”.

In the tropics, as the dead plant material builds up over time in areas covered with water, the areas farthest from the river drain more slowly than areas closer to the river, peat accumulates more rapidly in these areas farthest from the river, resulting in a dome shape. Understanding the local, fine scale patchiness of the landscape can improve our understanding of the dynamics of these tropical peatlands.

The AGU Fall Meeting is a massive meeting and I could only scratch the surface of all of the great research. If you could not make it, I encourage you to look at www.agu.org to explore more. There was also a lot of great work looking at  the food-water-nexus, the connections between water, energy, and food production. Look for a more in-depth post on that work next week!

Special thanks to Erin Swails and Ben Bond-Lamberty for some input on this article.