Spring break in Wisconsin!

Pulling coring equipment out to a small lake in Northern Wisconsin.

Perhaps Northern Wisconsin is not a typical spring break destination…it certainly doesn’t make any top ten lists.  However, for seven people from three universities (Lehigh University, University of Wisconsin, and University of Minnesota) it was our Miami Beach for the past week.  We did not do any body surfing or swimming; in fact, we were glad that the abundant lakes in this region were well frozen.  We did not do any ice fishing, skating, or skiing either.  Nor did we go to sample cheese.  We were there to travel back in time.

Alex Ireland (PhD student, Lehigh University) and Randy Calcote (Research Scientist, University of Minnesota) cutting the coring tube on Open Bog Lake.

 

Specifically, we went to collect sediment cores from several lakes as part of a project aimed at understanding how aquatic and wetland ecosystems have responded to past climate changes.  We are working in this region because there are abundant kettle depressions –  low areas occupied by lakes and wetlands that were formed many thousands of years ago as glaciers retreated northward following the last major glaciation.  These areas provide a range of ecological services, including wetland and aquatic habitat for biodiversity, sites for groundwater recharge, important roles in biogeochemical cycles (e.g., carbon storage), and areas for recreation.  Lake chemistry and regional groundwater flow has also been well characterized in this region of northern Wisconsin, because it is part of the US Long Term Ecological Research Network (North Temperate Lakes LTER).

Kettlehole ecosystems are also ideal for the study of past ecological responses to climate variability. They have significant linkages to the broader landscape through groundwater flow, are hydrologically sensitive to changes in precipitation, and most importantly, they leave a detailed record of their own development in the form of peat and lake sediments.  We are using the paleoecological record preserved in these ecosystems to determine how they have responded to climate changes of the past 10,000 years – and hopefully use this information to better anticipate how these and other ecological systems may change in the future.

Jennifer Schmitz (PhD student, University of Wisconsin), Alex Ireland (PhD student, Lehigh University), and Sara Hotchkiss (Associate Professor, University of Wisconsin) coring Triangle Lake.

Kettlehole basins are typically occupied by lakes, peatlands, or some combination these two habitat types.  Lakes that are bordered by extensive peatland are quite different in water chemistry and biological communities than those that lack adjacent peatland, and systems characterized by peatland can serve as large carbon sinks (i.e., they take carbon out of the atmosphere and store it as peat) and are therefore important when considering regional carbon budgets.  Data from other studies indicate that the establishment and expansion of peatland in kettlehole basins is triggered by moisture variability, particularly prolonged drought events, and peatland expansion can occur rapidly – probably within a decade or two.  Threshold responses like this are difficult to anticipate or predict.  Abrupt peatland expansion in these systems likely leads to rapid changes in carbon accumulation rates and alters lake-water chemistry and lake biota.  However, dynamics, rates, and characteristics of these changes are not well understood.

Although this trip was focused on coring lakes, we will return this summer to collect cores from the peatland component of these basins.    Below is a homemade video documentary showing the progress we made last week and the kind of work that is involved in the collection of lake sediments.  Over 30 meters of lake sediment has now been transported back to the laboratory, where it will be analyzed to obtain information on past environmental changes.  As you can see, spring break in Wisconsin was a lot of fun!

Video created using iMovie and a Canon Powershot D10 (waterproof!).  Music credits: Winter Wonderland (Sonny Rollins), I walk the line (Johnny Cash), Nice work if you can get it (Thelonious Monk), Cold water (Tom Waits), Broke down engine (Bob Dylan), When the levee breaks (Led Zeppelin), Two little feet (Greg Brown), Nameless Banjo Riff (Pete Seeger), All work and no play (Van Morrison).

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