Joseph von Fischer

Joseph von FischerAssociate Professor
Office: Anatomy/Zoology Building E435
Phone: 970-491-2679
Website: http://rydberg.biology.colostate.edu/vonfischerlab
Education: Ph.D., Ecology & Evolutionary Biology, Cornell University
Curriculum Vitae: Click to View
Email: Joe.von_Fischer@ColoState.EDU

I study how the function of ecosystems is structured by the interactions among plants, the soil and soil microbes. As compared to the ecological interactions we observe on the macroscopic scale, soil processes are particularly fragile (e.g.,the delicate relationship between root hair and soil mineral surface, gel-like biofilms feeding on root exudates, or the soil pores that conduct water and gases through the soil matrix). Because traditional soil sampling and incubation methods often destroy these structures, we know very little about the "micro-habitats" that affect the distribution, abundance and activity of plant roots and soil microbes. Most broadly, my research seeks to (1) characterize the soil as a landscape composed of diverse micro-habitats, and (2) understand the processes by which diversity in microhabitats affects the function of ecosystems.

I am especially interested in the greenhouse gas methane, in part because the metabolism of methane in soil is conducted by two groups of microbes with radically different ecologies: methane is produced by strictly anaerobic archaebacteria and consumed by aerobic bacteria. Thus I am interested in the factors that affect the oxic/anoxic status among and within soils that can structure the activities of the organisms in these two groups. Conversely, I am also interested in understanding how the activities of these groups provide information about the mix of oxic and anoxic microhabitats in the soil. Such measures have important direct implications for understanding the role of methane in climate change while simultaneously contributing toward a more detailed view of soil ecology.

To overcome the limitations imposed by traditional soil assays, I have developed and applied new, non-destructive methods for studying the organisms that metabolize methane in upland (e.g., forest or grassland) soils and in wetland ecosystems. Work in my lab typically couples stable isotope and other tracers with dynamical systems models in a way that reveals soil function with minimal disruption. My work with stable carbon isotopes has also enabled inquiry into the sources and fates of plant-derived carbon in the soil.

Molecular work in my lab has focused on funcational gene probes and clone library construction, coupled with ecophysiological measures of the target microbial community.  Using this approach, my students are investigating the value of incorporating microbial community composition into biogeochemical models.  Work in this area investigates both methane and nitrogen biogeochemistry.

Selected Publications

Dijkstra, F. A., J. A. Morgan, J. C. von Fischer, and R. F. Follett (2011), Elevated CO2 and warming effects on CH4 uptake in a semiarid grassland below optimum soil moisture, J. Geophys. Res., 116, G01007, doi:10.1029/2010JG001288.

von Fischer, J. C., R. C. Rhew, G. M. Ames, B. K. Fosdick, and P. E. von Fischer (2010), Vegetation height and other controls of spatial variability in methane emissions from the Arctic coastal tundra at Barrow, Alaska, Journal of Geophysical Research Biogeosciences, 115, G00I03, doi:10.1029/2009JG001283

Ostrom, N.E., R. Sutka, P.H. Ostrom, A.S. Grandy, K.M. Huzinga, H. Gandhi, J.C. von Fischer and G.P. Robertson (2010) “Isotopologue data reveal bacterial denitrification as the primary source of N2O during a high flux event following cultivation of a native temperate grassland” Soil Biology and Biochemistry 42:499-406.

Mazéas, O., J. C. von Fischer, and R. C. Rhew (2009), Impact of terrestrial carbon input on methane emissions from an Alaskan Arctic lake, Geophysical Research Letters, 36, L18501, doi:10.1029/2009GL039861.

von Fischer, J. C., G. Butters, P. C. Duchateau, R. J. Thelwell, and R. Siller (2009), In situ measures of methanotroph activity in upland soils: A reaction-diffusion model and field observation of water stress, Journal of Geophysical. Research., 114, G01015, doi:10.1029/2008JG000731.

Nordt, L., J. von Fischer, L.L Tieszen and J. Tubbs. (2008). "Coherent changes in relative C4 plant productivity and climate during the late Quaternary in the North American Great Plains." Quaternary Science Reviews 27(15-16): 1600-1611.

von Fischer, J.C., L.L. Tieszen and D.S. Schimel (2008) “Climate controls on C3 vs. C4 productivity in North American grasslands from carbon isotope composition of soil organic matter.” Global Change Biology. 14(5): 1141-1155.

von Fischer, J. C., and L. O. Hedin (2007) "Controls on soil methane fluxes: Tests of biophysical mechanisms using stable isotope tracers", Global Biogeochemical Cycles, 21, GB2007, doi:10.1029/2006GB002687.

Nordt L., J.C. von Fischer and L.L. Tieszen (2007) “Late Quaternary temperature record from buried soils of the North American Great Plains.” Geology 35:159-162.

Suwa, M., J.C. von Fischer, M.L. Bender, A. Landais, and E.J. Brook (2006) "Chronology reconstruction for the disturbed bottom section of the GISP2 and the GRIP ice cores: Implications for Termination II in Greenland." Journal of Geophysical Research, 111, D02101, doi:10.1029/2005JD006032.

von Fischer J.C. and L.O. Hedin (2002) “Separating methane production and consumption with a field-based isotope pool dilution technique.”  Global Biogeochemical Cycles 16(3) 8.1-8.12.

Ostrom N.E., L.O. Hedin, J.C. von Fischer and G.P. Robertson. (2002) “Nitrogen transformations at a soil-stream interface: a stable isotope approach.” Ecological Applications 12(4) 1027-1043.

Hedin L.O., J.C. von Fischer, N.E. Ostrom, B.P. Kennedy, M.G. Brown, and G.P. Robertson (1998) “Thermodynamic constraints on nitrogen transformations and other biogeochemical processes at soil-stream interfaces.” Ecology 79(2):684-703.

von Fischer J.C. and L.L Tieszen (1995) “Carbon isotope characterization of four tropical forests in Luquillo, Puerto Rico.” Biotropica 27(2):138-148.