Welcome to Prof. David Bowling

Prof. Bowling, a biogeoscientist from the University of Utah, is visiting the Institute of Ecology as an LFUI Guest Professor, hosted by Michael Bahn. Prof. Bowling's research focuses on the cycling of ecologically-important elements within and between terrestrial ecosystems, the atmosphere, the hydrosphere, and the geosphere.
Dave Bowling
(Credit: D. Bowling)

The field of biogeoscience investigates how living things in their natural habitats are affected by biological, physical, and chemical factors, how these organisms modify their environment, and the processes that control cycling of elements and resources such as carbon, water, and nutrients. This research is interdisciplinary, requiring collaboration with colleagues from a variety of scientific disciplines, including atmospheric science, geochemistry, hydrology, microbial ecology, and plant physiology.

The research visit is aimed at evaluating new technology for monitoring stable isotopes in nature.  Isotopes are variations of atoms with additional neutrons in their nucleus, with unaltered chemistry; they participate in biophysical and biogeochemical reactions just like their normal counterparts.  Isotopes can be radioactive (such as carbon-14), but all elements have one or more stable isotopes.  Carbon-12 and carbon-13 are stable isotopes of carbon, they are natural and safe, and variations in the relative amounts of these do not change over time as with radioactive decay of carbon-14. 

The light elements that make up biological and ecological systems (carbon, hydrogen, oxygen, nitrogen) all vary isotopically, and the differences in stable isotope composition of things like water, plant leaves, butterfly wings, or atmospheric gases provides information about processes in nature.  New insight can be obtained about ecological processes by examining variation of stable isotopes, including natural variation, but also via experimental addition of an isotopic label.  For example, by watering communities of plants with water that has an unusual isotopic composition of the hydrogen or oxygen atoms of the water, one can determine how plants use and transport water by measuring the isotopes of water within the plant, and in plant tissues such as the leaves or wood.

Since the 1930s, stable isotopes have been measured using laboratory-based isotope ratio mass spectrometry.  This method is highly sensitive but the instrumentation cannot be used in remote locations.  In the last 15 years, several new instruments have become commercially available that allow stable isotopes of carbon dioxide, methane, water vapor, and other trace gases to be measured in real-time and in remote locations.  These techniques are based on the principles of infrared absorption spectroscopy.

Recently, scientists have begun to use these instruments in combination with artificial isotope labelling.  In Prof. Bahn's group, plants in a mountain grassland in the Stubai Valley are provided with labelled carbon dioxide which they assimilate via photosynthesis.  This leads to incorporation of the label in organic compounds within the plant, which can be traced through the plant-soil system and back to the atmosphere, providing information about the allocation and residence time of carbon within the grassland.  This application results in measurement of samples that are far outside the normal range of isotope ratios observed in nature.  To date, no one has evaluated the suitability of these instruments for these unusual applications.  We are conducting a lab-based testing program for these instruments, two of which are based at the University of Innsbruck.  This visit will involve continued instrumentation testing, data analysis and synthesis of lab testing results, and evaluation of field experimental results from Prof. Bahn’s on-going experiments in mountain grassland.


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