Sharon Billings - Global Change Biology and Biogeochemistry
Assistant Professor
Ph.D., Duke University
Kansas Biological Survey
Higuchi Hall
Phone: (785) 864-1560 (office)
Fax: (785) 864-1534
Increasing human population is resulting in accelerated environmental changes around the globe. Such shifts include increasing concentrations of “greenhouse gases” such as CO2 and nitrous oxide (N2O), habitat destruction and fragmentation, changing land uses, and increasing rates of nitrogen (N) deposition. All of these processes can dramatically affect the biogeochemical cycles that sustain life on Earth, either directly or indirectly. The Billings lab explores the effects of these changes on numerous parameters, so I broadly define myself as a global change biologist.
The lab currently focuses on how global environmental changes can alter terrestrial ecosystem carbon (C), N, and water fluxes in soil organic matter (SOM) and aboveground biomass. Terrestrial SOM contains more than three times the C content of the atmosphere, and more than five times terrestrial biomass C! Because the global C cycle is so integral to maintaining Earth’s climate, understanding how soils incorporate, process, and store this astounding quantity of C is critical. Microbial processing of SOM can determine the ability of a soil to sequester C, a valuable ecosystem service. This microbial activity is dependent on and governs nutrient supplies in the soil matrix. Thus, understanding N inputs to, cycling within, and losses from ecosystems is critical for our understanding of soil C dynamics. Humans have dramatically accelerated ecosystem N cycling, largely through fertilization and atmospheric N deposition. The ramifications of these changes are not yet understood. Much work in my lab centers on these principals. We use a combination of laboratory and field techniques to explore these issues, ranging from established soil science methods and microbiological assays to plant physiological techniques. A significant part of my research uses stable isotopes as a tool, both at natural abundance levels and as tracers in soils and plants.
·Schaeffer, S.M., Billings, S., Evans, R.D. 2007. Laboratory incubations reveal potential responses of soil nitrogen cycling to changes in soil C and N availability in Mojave Desert soils exposed to elevated atmospheric CO2. Global Change Biology 13:854-865, DOI 10.111/j.1365-2486.2007.01324.x
·Billings, S. 2006. Soil organic matter dynamics and land use change at a grassland/forest ecotone. Soil Biology and Biochemistry 38:2934-2943.
·Billings, S., Richter, D.D. 2006. Changes in stable isotopic signatures of soil nitrogen and carbon during forty years of forest development.
Oecologia 148: 325-333, DOI 10.1007/s00442-006-0366-7.
·Billings, S., Brewer, C.M., Foster, B. 2006. Incorporation of plant residues into soil organic matter fractions with grassland management practices in the North American Midwest. Ecosystems 9: DOI:
10.1007/s10021-006-0080-7.
·Billings, S., Ziegler S. 2005. Linking microbial activity and soil organic matter transformations in forest soils under elevated CO2. Global Change Biology 11:203-212.
·Billings, S., Schaeffer, S.M., Evans, R.D. 2004. Response of soil microbial activity and N mineralization to elevated CO2 in Mojave Desert soils.
Global Biogeochemical Cycles 18:GB1011, doi:10,1029/2003GB002137.
·Billings, S., Zitzer, S., Weatherley, H., Schaeffer, S.M., Charlet, T., Arnone, J., Evans, R.D. 2003. Effects of elevated CO2 on green tissue and litter quality in an intact Mojave Desert ecosystem. Global Change Biology 5:729-735.
·Billings, S., Schaeffer, S.M., Evans, R.D. 2003. Nitrogen fixation by biological soil crusts and free-living bacteria in an intact Mojave Desert ecosystem with elevated CO2 and added soil carbon. Soil Biology and Biochemistry 35:643-649.
·Schaeffer, S.M., Billings, S.A., Evans, R.D. 2003. Responses of nitrogen dynamics in an intact Mojave Desert ecosystem to manipulations in soil carbon and nitrogen availability. Oecologia 134:547-553.
·Billings, S., Schaeffer, S.M., Zitzer, S., Evans, R.D. 2003. Trace N gas losses and N mineralization in an intact Mojave Desert ecosystem with elevated CO2. Soil Biology and Biochemistry 34:1777-1784.
·Billings, S., Schaeffer, S.M., Zitzer, S., Charlet, T., Smith, S.D., Evans, R.D. 2002. Alterations of nitrogen dynamics under elevated CO2 in an intact Mojave Desert ecosystem: evidence from d15N. Oecologia 131:463-467.
·Yarie, J., Billings, S. 2002. Carbon balance of the taiga forest within
Alaska: present and future. Canadian Journal of Forest Research 32:757-767.
·Billings, S., Richter, D., Yarie, J. 2000. Sensitivity of soil methane fluxes to an altered precipitation regime in boreal forest soils. Soil Biology and Biochemistry 32:1431-1441.
·Billings, S., Richter, D., Yarie, J. 1998. Soil carbon dioxide fluxes and profile concentrations in two boreal forests. Canadian Journal of Forest Research 28:1773-1783.
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