Linking groundwater and nutrients to monitor fen ecosystems using airbone imaging spectroscopy

Current students working on this project

• Arthur Ryzak, graduate student

Research topics

  • Fen
  • Wetland
  • Groundwater
  • Remote sensning
  • Spectroscopy
  • Nutrients


Research description

Fens are a type of mire wetland that are at least in part dependent upon groundwater, and are home to a rich variety of rare plants that can survive under the stressful hydrology, chemistry, and low nutrient status that is associated with the presence of alkaline groundwater.  Historically, wetlands such as fens have been well mapped, as they have been known to halt the progress of armies; and knowledge of the location locations has provided a strategic advantage on the battlefield. More recently, it has been recognized that wetlands provide important ecosystem services, such as flood control and water quality enhancement, and at this time they are protected by the EPA and the Army Corps of Engineers from filling and dredging for uses in development and agriculture. But as the population grows and resources become stressed, new  battlefronts are emerging in policy concerning the fate of wetlands such as fens.  What are the factors that regulate the health of fens, and how have the health of fens changed over time? What if the high capacity groundwater wells associated with certain types of agriculture also effect the viability of fens? How will appropriate decisions be made regarding the protection of fens? It is clear that in order to answer these questions, the mapping and delineation of fens will still be important moving into the future. However, as budgeted funds for field mapping excursions have dwindled over the years, the slack will need to be taken up by utilizing good data, the best available technology, and sound science.

The University of Wisconsin Madison (UW-Madison) has been collecting good data on fens for many years. As a recent example; since 2015, data have been collected throughout the growing season on a bi-weekly basis for six fens in southern Wisconsin. The manually collected data include a set of wells and piezometers at each of twenty test plots that establish water table elevation and vertical hydraulic gradient at various locations throughout the fen.  At each of these plot locations, the vegetation present has been identified and quantified. Soil samples have also been collected and analyzed for nutrients, and volumetric water content, soil water conductivity, and soil temperature have all been recorded. In addition, automated and continuous data are also available for each fen from a weather station and various soil probes. Thus, there has been a wealth of data collected regarding the hydrology, edaphic conditions, and plant communities associated with these fens over the past few years, and collection of this data will continue into the near future.

UW-Madison is also at the forefront of research utilizing Remote Sensing Imaging Spectroscopy (RSIS), and continues to acquire some of the best available technology. Hyperspectral signatures (400nm – 2500 nm) of the vegetation present at each of the fen test plots is currently being obtained using portable spectrometers. Additionally, the university has recently acquired a plane-based hyperspectral imager capable of 20cm spatial resolution, within the same spectral limits. Flights over the six fens with the new hyperspectral camera are currently in progress, and will continue into 2018.

And so, we are gathering a lot of good ground data about the hydrology and chemistry of fens, and are also obtaining cutting edge RSIS data as well. One challenge we will face in the next couple years will be how to link these various sources of data objectively, using sound science, so as to reach meaningful conclusions about the presence/detection of fens, as well as factors influencing their degradation status. If successful, new tools will be made available to decision makers, so as to best identify and manage these shared resources.