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Department of Natural Resource Ecology and Management

NREM Faculty - Steve W. Hallgren

Associate Professor

022 Agricultural Hall (office)
008C Agricultural Hall (address)
Stillwater, OK 74078

Educational Background
BS: University of Minnesota, St. Paul; Forest Science; 1972
MS: Oregon State University, Corvallis; Forest Ecology; 1978
PhD: University of California, Berkeley; Forest Biology; 1984



  • NREM 3213: Forest Ecology
  • NREM 3713: Wildland Fire Ecology and Management
  • HONOR 1000: Expand Your Horizons: What Study Abroad is Really About

Research Interests:
A major research focus is the role of fire in the Cross Timbers, a mosaic of forest, savannah and tall-grass prairie in the ecotone between the eastern deciduous forest and the southern Great Plains.  Fire has been excluded from much of the area for decades and its reintroduction will require better knowledge of interactions between vegetation, climate and fire.  A current study concerns the effects of fire frequency on plant biodiversity and forest composition and structure.  Studies are underway concerning fire effects on ecosystem functions including mineral nutrient cycling, decomposition, wildlife habitat, and carbon storage.

Honors and Awards

  • 2001 Full Year Sabbatical Leave with INRA (French National Institute for Agronomic  Research) Avignon
  • 1993 Full Year Sabbatical Leave, Fulbright Senior Scholar, Lehrstuhl für Pflanzenökologie, Universität Bayreuth , Germany

Professional Memberships

  • Scientific Board, Annals of Forest Science
  • OSU Fulbright Program Advisor
  • Society of American Foresters
  • Oklahoma Academy of Science


  • Forestry Graduate Education Committee, Chair
  • DASNR International Program Advisory Committee, Member
  • Plant Sciences Program Steering Committee, Member
  • CASNR Environmental Sciences Undergraduate Program Steering Committee, Member
  • NEON Southern Plains, Domain Science and Education Coordinating Committee, Chair

Recent Publications (since 2008)
Willliams, R.J., Hallgren, S.W., Wilson, G.W.T. and Palmer, M.W. 2013. Juniperus virginiana encroachment into upland oak forests alters arbuscular mycorrhizal abundance and litter chemistry. Appl. Soil Ecol. In Press.

Polo, J.A., Hallgren, S.W., and Leslie, D.M. 2012. Effect of long-term understory prescribed burning on standing and down dead woody material in dry upland oak forests. For. Ecol. Manage. In Press.

Hallgren, S.W., DeSantis, R.D., and Burton, J.A. 2012. Fire and vegetation dynamics in the Cross Timbers forests of south-central North America. Pages 52-66 in Dey, D.C., Stambaugh, M.C., Clark, S.L., and Schweitzer, C.J. (eds.) Proceeding of the 4th Fire in Oak Forests Conference. US Forest Service, Northern Research Station. Gen. Tech. Report NRS-P-102.

Willliams, R.J., Hallgren, S.W., and Wilson, G.W.T. 2012. Frequency of prescribed burning in an upland oak forest determines soil and litter properties and alters the soil microbial community. For. Ecol. Manage. 265:241-247.

DeSantis, R.D., Hallgren, S.W., and Stahle, D.W. 2011. Drought and fire suppression lead to rapid forest composition change in a forest-prairie ecotone. For. Ecol. Manage. 261:1833-1840.

Burton, J.A., Hallgren, S.W., Fuhlendorf, S.D., and Leslie, D.M., Jr. 2011. Understory response to varying fire frequencies after 20 years of prescribed burning in an upland oak forest. Plant Ecol. 212:1513–1525.

DeSantis, R.D., and Hallgren, S.W. 2011. Prescribed burning frequency affects post oak and blackjack oak regeneration. South. J. Appl. For. 35:193-198.

Burton, J.A., Hallgren, S.W. and Palmer, M.W. 2010. Fire frequency effects on structure and composition of xeric oak forests. Nat. Areas J. 30:370-379.

DeSantis, R.D., Hallgren, S.W., and Stahle, D.W. 2010. Fire regime of an upland oak forest in south-central North America. Fire Ecol. 6:45-61.

DeSantis, R.D., Hallgren, S.W., Palmer, M.W., Lynch, T.B., and Burton, J.A. 2010. Long-term directional changes in the upland oak forests of Oklahoma, USA. J. Veg. Sci. 21:606-615.