People

Dean Pearson

Dean Pearson

Research Ecologist - USFS

Office: Forestry Sciences Lab, 800 E. Beckwith Ave.
Email: dpearson@fs.fed.us

Curriculum Vitae

Current Position

Research Ecologist (community ecology emphasis), Rocky Mountain Research Station, USDA Forest Service.  Faculty affiliate with Division of Biological Sciences, UM.

Personal Summary

My primary interest lies in integrating community and invasion ecology to advance these fields of research and improve invasives management. Ecological theory is founded on traditional manipulation experiments, where we attempt to understand processes of community assembly by removing individual system components and examining the outcome. However, even relatively recent species assemblages in the northern United States represent collections of organisms that have had roughly 11,000 years to interact and assemble themselves. Thus, simple manipulation experiments can be misleading. Biological invasions represent massive natural experiments whereby a completely novel organism enters into a new system and either fails to establish, establishes with little effect or establishes and completely disrupts the recipient community and forces it to reassemble. Thus, biological invasions provide acid tests for ecological theory by illustrating processes of community assembly and disassembly before our eyes. Such experiments provide unique research opportunities to simultaneously advance ecological theory and improve invasive species management.  

Education

University of Montana  Organismal Biology and Ecology  Ph.D. May 2005
University of Montana  Organismal Biology and Ecology  M.A.S. May 1995
University of Montana  Wildlife Biology                              B.S. March 1992
 

Projects

Biogeography of plant invasions

Predator and consumer effects in grassland ecosystems

How strong invaders break the rules

Field of Study

Community ecology, invasion ecology, predator-prey interactions, indirect interactions

Selected Publications

  1. Pearson, D.E., Eren, Ö., Ortega, Y.K., Villareal, D., Şentürk, M., Miguel, M. F., Weinzettel, C. M., Prina, A. and Hierro, J.L.  In press.  Are exotic plants more abundant in the introduced versus native range?  Journal of Ecology
  2. Zhong, Z., Xiaofei, L., D. E. Pearson, W. Deli, D. Sanders, Y. Zhu, and L. Wang.  In press.  Ecosystem engineering strengthens bottom-up and weakens top-down effects via trait-mediated indirect interactions.  Proceedings of the Royal Society B, doi.org/10.1098/rspb.2017.0894
  3. Pearson, D.E., Y.K. Ortega, and J.L. Maron. 2017.  The tortoise and the hare: reducing resource availability shifts competitive balance between plant species.  Journal of Ecology 105, 999-1009.
  4. Pearson, D.E., Y.K. Ortega, J. Runyon, and J. Butler.  2016. Secondary invasion: the bane of weed management.  Biological Conservation 197:8-17.
  5. Pearson, D.E., Icasatti, N., J.L. Hierro, and B. Bird.  2014.  Are local filters blind to provenance? Ant seed predation suppresses exotic plants more than natives.  PLoS ONE 9(8): e103824. doi:10.1371/journal.pone.0103824
  6. Pearson, D.E., T. Potter, and J.M Maron.  2012. Biotic resistance: exclusion of native rodent consumers releases populations of a weak invader.  Journal of Ecology 100:1383-1390.
  7. Pearson, D.E., R.M. Callaway, J.L. Maron.  2011. Biotic resistance via granivory: establishment by invasive, naturalized and native asters reflects generalist preference.  Ecology 92:1748-1757.
  8. Pearson, D. E.  2010.  Trait- and density- mediated indirect interactions initiated by an exotic plant autogenic ecosystem engineer.  The American Naturalist 176:394-403.
  9. Pearson, D. E. and R. M. Callaway.  2006.  Biological control agents elevate hantavirus by subsidizing mice. Ecology Letters 9:443-450.
  10. Pearson, D. E. and R. M. Callaway.  2003.  Indirect effects of host-specific biological control agents.  Trends in Ecology and Evolution 18(9):456-461.

Publications

  1. Pearson, D.E., Eren, Ö., Ortega, Y.K., Villareal, D., Şentürk, M., Miguel, M. F., Weinzettel, C. M., Prina, A. and Hierro, J.L.  In press.  Are exotic plants more abundant in the introduced versus native range?  Journal of Ecology
  2. Zhong, Z., Xiaofei, L., D. E. Pearson, W. Deli, D. Sanders, Y. Zhu, and L. Wang.  In press.  Ecosystem engineering strengthens bottom-up and weakens top-down effects via trait-mediated indirect interactions.  Proceedings of the Royal Society B, doi.org/10.1098/rspb.2017.0894
  3. Larios, L., D.E. Pearson, and J.L. Maron.  2017.  Incorporating the effects of generalist seed predators into plant community theory.  Functional Ecology, doi: 10.1111/1365-2435.12905
  4. Pearson, D.E., Y.K. Ortega, and J.L. Maron. 2017.  The tortoise and the hare: reducing resource availability shifts competitive balance between plant species.  Journal of Ecology 105, 999-1009.
  5. Loehman, R.A., B.B. Bentz, G.A. DeNitto, R.E. Keane, M.E. Manning, J.P. Duncan, J.M. Egan, M.B. Jackson, S. Kegley, I.B. Lockman, D.E. Pearson, J.. Powell, S. Shelly, B.E. Steed, and P.J. Zambino.  2017.  Effects of Climate Change on Ecological Disturbance in the Northern Rockies.  In J.E. Halofsky, D.L. Peterson (eds.), Climate Change and Rocky Mountain Ecosystems, Advances in Global Change Research 63, DOI 10.1007/978-3-319-56928-4_7
  6. Pearson, D.E., Y.K. Ortega, J. Runyon, and J. Butler.  2016. Secondary invasion: the bane of weed management.  Biological Conservation 197:8-17.
  7. Rudgers, J.A., B. Fletcher, E. Olivas, C.A. Young, N.D. Charlton, D.E. Pearson, and J.L. Maron.  2016. Exclusion of ungulates reduces fungal symbiont frequency within host plants in native grasslands. Oecologia 181:1151-1161.
  8. Pearson, D.E., Y.K. Ortega, O. Eren, J.L. Hierro.  2016.  Quantifying “apparent” impact and distinguishing impact from invasiveness in multispecies plant invasions.  Ecological Applications 26:162-173.
  9. Maron, J.L., Smith, A., Pearson, D.E., Ortega, Y.K., and R.M. Callaway.  2016.  Negative plant-soil feedbacks increase with plant abundance, and are unchanged by competition.  Ecology 97:2055-2063.
  10. Smith, J.N., Emlem, D.J., and Pearson, D.E. 2016. Community reassembly: web spider community restructuring following simulated plant invasion.  PLoS One 11(4): e0153661. doi:10.1371/journal.pone.0153661
  11. Pinto, S.M., D. E. Pearson, J.L. Maron.  2014.  Seed dispersal is more limiting to grassland diversity than competition or seed predation. Journal of Ecology 102:1258-1265.
  12. Pearson, D.E., Icasatti, N., J.L. Hierro, and B. Bird.  2014.  Are local filters blind to provenance? Ant seed predation suppresses exotic plants more than natives.  PLoS ONE 9(8): e103824. doi:10.1371/journal.pone.0103824
  13. Connolly, B., Pearson, D. E., and Mack, R. N. 2014.  Granivory of invasive, naturalized, and native plants in communities differentially susceptible to invasion.  Ecology 95: 1759-1769.
  14. Ortega, YK, Greenwood, L., Callaway, R.M. and Pearson, D.E.  2014. Differential response of congeneric consumers to an exotic food resource: who gets the novel resource prize?  Biological Invasions 16:1757-1767.
  15. Maron, J.L., Auge, H., Korell, L., D. E. Pearson, Hensen, I., Suding, K.N., and C. Stein.  2014.  Staged invasions across disparate grasslands: effects of seed provenance, consumers, and disturbance on productivity and species richness.  Ecology Letters 17:499-507.
  16. Pearson, DE, JL. Hierro, M. Chiuffo and D. Villarreal. 2014. Rodent seed predation as a biotic filter influencing exotic plant abundance and distribution. Biological Invasions 16: 1185-1196.
  17. Litt, A., and D. E. Pearson.  2013.  Nonnative plants and wildlife in the Intermountain West.  Wildlife Society Bulletin 37:517-526.
  18. Pearson, D.E., T. Potter, and J.M Maron.  2012. Biotic resistance: exclusion of native rodent consumers releases populations of a weak invader.  Journal of Ecology 100:1383-1390.
  19. Maron, J.L., D. E. Pearson, T. Potter, and Y. K. Ortega. 2012. Seed size and provenance mediate the joint effects of disturbance and seed predation on community assembly. Journal of Ecology 100:1492-1500.
  20. Ortega, YK, Pearson, DE, Waller, LP, Sturdevant, NJ., Maron, JM.  2012.  Population-level compensation impedes biological control of an invasive forb and indirect release of a native grass. Ecology 93:783-792.
  21. Pearson, D. E., Y. K. Ortega, and S. Sears.  2012. Darwin’s naturalization hypothesis up-close: intermountain grassland invaders differ morphologically and phenologically from native community dominants.  Biological Invasions 14:901-913.
  22. Zwolak, R., D. E. Pearson, Y. K . Ortega, E. E. Crone. 2012. Mechanisms driving post-fire increase of a generalist mammal.  Canadian Journal of Zoology 90:51-60.
  23. Pearson, D.E., R.M. Callaway, J.L. Maron.  2011. Biotic resistance via granivory: establishment by invasive, naturalized and native asters reflects generalist preference.  Ecology 92:1748-1757.
  24. Maron, J. L., and D. E. Pearson.  2011. Vertebrate predators have minimal cascading effects on plant production or seed predation in an intact grassland ecosystem. Ecology Letters 14:661-669.
  25. Pearson, D. E., M. Kim, and J. Butler.  2011.  Rocky Mountain Research Station invasive species visionary white paper.  Gen. Tech. Rep. RMRS-GTR-265. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 38 p.
  26. Ortega Y.K., and D.E. Pearson.  2011.  Long-term effects of weed control with picloram along a gradient of spotted knapweed invasion.  Rangeland Ecology and Management 64: 67-77.
  27. Pearson, D. E.  2010.  Trait- and density- mediated indirect interactions initiated by an exotic plant autogenic ecosystem engineer.  The American Naturalist 176:394-403.
  28. Maron, J. L., D. E. Pearson, and R. Fletcher, Jr.  2010.  Counter-intuitive effects of large-scale predator removal on a mid-latitude rodent community.  Ecology 91: 3719-3728.
  29. Ortega Y.K., and D.E. Pearson. 2010. Effects of picloram application on community dominants vary with initial levels of spotted knapweed (Centaurea stoebe) invasion   Invasive Plant Science and Management 3:70-80.
  30. Zwolak, R., D.E. Pearson, Y.K .Ortega, E.E. Crone.  2010.  Fire and mice: seed predation moderates fire's influence on conifer recruitment.  Ecology 91:1124-1131.
  31. Maron, J.L., D. E. Pearson, S. M. Hovick, W. P. Carson.  2010.  Funding needed for assessments of weed biological control.  Frontiers in Ecology and the Environment 8:122-123.
  32. Bricker, M., D. E. Pearson and J. L. Maron.  2010. Small mammal seed predation reduces forb recruitment and abundance in semi-arid grasslands.  Ecology 91:85-92.
  33. Finch, D. M., Pearson, D. E, Wunderle, J. and Arendt, W.  2010.  Terrestrial animals in the invasive species strategy plan.  Pages 43-54 In (Eds) Dix, M.E.; Britton, K., comps. 2010. A dynamic invasive species research vision: Opportunities and priorities, 2009-2029. Gen. Tech. Rep. WO-79. Washington, DC: U.S. Department of Agriculture, Forest Service.
  34. Pearson, D. E.  2009.  Invasive plant architecture alters trophic interactions by changing predator abundance and behavior.  Oecologia 159:549-558. 
  35. Pearson, D. E. 2009.  Biological invasions on oceanic islands: implications for island ecosystems and avifauna.  Pages 3-14 in Proceedings of the 3rd International Symposium on Migratory Birds.  Seabirds in Danger: Invasive Species and Conservation of Island Ecosystems.  Keynote Address, 25 September 2009, Mokpo, Korea.
  36. Crone, E.E., M. Marler, D.E. Pearson. 2009. Non-target effects of broadleaf herbicide on a native perennial forb: a demographic framework for assessing and minimizing impacts. Journal of Applied Ecology 46:673-682.
  37. Pearson, D. E. and Y. K. Ortega.  2009.  Managing invasive plants in natural areas: moving beyond weed control, pp 1-21, in (ed.) R.V. Kingley, Weeds: Management, Economic Impacts and Biology. Nova Publishers, NY
  38. Pearson, D. E. and R. M. Callaway. 2008.  Weed biocontrol insects reduce native plant recruitment through second-order apparent competition.  Ecological Applications 18:1489-1500.
  39. Pearson, D. E. and R. J. Fletcher, Jr.  2008.  Mitigating exotic impacts: restoring native deer mouse populations elevated by an exotic food subsidy.  Ecological Applications18 (2):321-334.
  40. Sturdevant, N., Kegley, S., Ortega, Y., and D. Pearson. 2006. Evaluation of establishment of Cyphocleonus achates and its potential impact on spotted knapweed. USDA FS FHP General Technical Report 06-08:1-9.
  41. Shick, K. R., D. E. Pearson, and L. F. Ruggiero.  2006.  Forest habitat associations of the golden-mantled ground squirrel: implications for fuels management.  Northwest Science 80:133-139.
  42. Pearson, D. E. and R. M. Callaway.  2006.  Biological control agents elevate hantavirus by subsidizing mice. Ecology Letters 9:443-450.
  43. Pearson, D. E., and R. M. Callaway.  2005.  Indirect nontarget effects of host-specific biological control agents: implications for biological control.  Biological Control 35:288-298.
  44. Ortega, Y. K., and D. E. Pearson.  2005.  Strong versus weak invaders of natural plant communities: assessing invasibility and impact.  Ecological Applications 15:651-661.
  45. Pearson, D.E. 2005. Biological control is more than just natural enemies.  Review of Natural Enemies: an Introduction to Biological Control.  Trends in Ecology and Evolution 20: 10-11.
  46. Pearson, D. E. and R. M. Callaway.  2004.  Response to Thomas et al.: biocontrol and indirect effects.  Trends in Ecology and Evolution 19:62-63.
  47. Ortega, Y. K., D. E. Pearson, and K. S. McKelvey. 2004. Effects of biological control agents and exotic plant invasion on deer mouse populations. Ecological Applications 14:241-253.
  48. Pearson, D. E. and R. M. Callaway.  2003.  Indirect effects of host-specific biological control agents.  Trends in Ecology and Evolution 18(9):456-461.
  49. Pearson, D. E., Y., K. Ortega, and L. F. Ruggiero. 2003. Trap-induced mass declines in small mammals and the implications for body mass as a negatively biased index.  Journal of Wildlife Management 67(4):684-691.
  50. Pearson, D. E., and L. F. Ruggiero.  2003.  Transect versus grid trapping arrangements for sampling small mammal communities. Wildlife Society Bulletin 31(2): 454-459.
  51. McKelvey, K. S., and D. E. Pearson.  2001.  Population estimation with sparse data: the role of indices versus estimators revisited.  Canadian Journal of Zoology 79(10):1754-1765.
  52. Ortega, Y. K., and D. E. Pearson.  2001.  Occurrences of the western skink (Eumeces skiltonianus) in grasslands of western Montana.  Northwestern Naturalist 82:125-125.
  53. Pearson, D. E., and Y. K. Ortega. 2001.  An indirect dispersal pathway for spotted knapweed seeds via deer mice and great-horned owls. Canadian Field-Naturalist 115(2):354.
  54. Pearson, D. E., Y. K. Ortega, K. S. McKelvey, and L. F. Ruggiero.  2001.  Small mammal communities and habitat selection in Northern Rocky Mountain bunchgrass: implications for exotic plant invasions.  Northwest Science 75(2):107-117. 
  55. Pearson, D. E., and L. F. Ruggiero.  2001.  Test of a prey-base hypothesis for American marten use of red squirrel middens. Canadian Journal of Zoology 79(8):1372-1379.
  56. Pearson, D. E.  2000.  Evidence of red-squirrel fall breeding in western Montana.  Canadian Field-Naturalist 114(4):703-704.
  57. Pearson, D. E., K. S. McKelvey, and L. F. Ruggiero.  2000. Non-target effects of an introduced biological control agent on deer mouse ecology. Oecologia 122(1):121-128.
  58. Buskirk, S. W., L. F. Ruggiero, K. B. Aubry, D. E. Pearson, J Squires, and K. S. McKelvey.  1999.  Comparative ecology of lynx in North America.  Pp. 397-417 In L.F. Ruggiero, K.B. Aubry, S.W. Buskirk, G.M. Koehler, C.J. Krebs, K.S. McKelvey, and J.R. Squires (eds.) Ecology and conservation of lynx in the United States.  University Press of Colorado, Colorado, USA.
  59. Pearson, D. E.  1999.  Deer mouse predation on the biological control agent, Urophora spp., introduced to control spotted knapweed.  Northwestern Naturalist 80(1): 26-29.
  60. Pearson, D. E.  1999.  Small mammals of the Bitterroot National Forest: a literature review and annotated bibliography.  UDSA Forest Service, General Technical Report RMRS-GTR-25.
  61. Foresman, K. R., and D. E. Pearson.  1999.  Activity patterns of American martens, fishers, snowshoe hares, and red squirrels in westcentral Montana.  Canadian Field-Naturalist 113(3):1-4.
  62. Foresman, K. R., and D. E. Pearson.  1998.  Comparison of proposed survey procedures for detection of forest carnivores.  Journal of Wildlife Management 62(3):1217-1226.
  63. Ruggiero, L. F., D. E. Pearson, S. E. Henry.  1998.  Characteristics of American marten den sites in Wyoming.  Journal of Wildlife Management 62(2):663-673.

Honors

National Forest System Invasive Species Program Award for Landscape Restoration and Rehabilitation Against Invasive Species, March 2012, Dr. Dean Pearson, Rocky Mountain Research Station, in recognition of his high level of leadership and expertise on invasion biology and invasive species management, linking management concepts to long-term landscape restoration and rehabilitation. 

Visionary Science Publication Award, USDA Forest Service, Rocky Mountain Research Station, January 2013, for the publication: Pearson, D. E. and R. M. Callaway.  2003.  Indirect effects of host-specific biological control agents.  Trends in Ecology and Evolution 18(9):456-461.

National Academy of Sciences, Kavli Fellow Recipient, 5 November 2010.

Presidential Early Career Award for Science and Engineering (PECASE).  July 2009. "Selection for this award is based on the combination of innovative research at the frontiers of science and technology and community service demonstrated through scientific leadership and community outreach.”

Deputy Chief’s Early Career Scientist Award.  Received 25 March 2009 in Washington D.C.  This honor was awarded in recognition of significant contributions to the fields of biological control, invasive species ecology, and wildlife biology.

Best Scientific Publication Award, USDA Forest Service, Rocky Mountain Research Station, Feb 2009, for the publication: Ortega, Y.K and D. E. Pearson.  2005. Strong versus weak invaders of natural plant communities: distinguishing invasibility from impact.  Ecological Applications 15:651-661. 

Best Scientific Publication Award, USDA Forest Service, Rocky Mountain Research Station, October 2007, for the publication: Pearson, D. E. and R. M. Callaway.  2006.  Biological control agents elevate hantavirus by subsidizing mice. Ecology Letters 9:442-449.

Early Career Scientist Publication Award, USDA Forest Service, Rocky Mountain Research Station, March 2005, for the publication: Ortega, Y. K., D. E. Pearson, and K. S. McKelvey. 2004. Effects of introduced biological control agents and exotic plant invasion on native deer mouse populations. Ecological Applications 14:241-253.

Early Career Scientist Publication Award, USDA Forest Service, Rocky Mountain Research Station, March 2001, for the publication: Pearson, D. E., K. S. McKelvey, and L. F. Ruggiero.  2000. Non-target effects of an introduced biological control agent on deer mouse ecology. Oecologia 122(1):121-128.
 

Teaching Experience

I serve primarily as a graduate student advisor or member of graduate student committees.

Professional Experience

Deputy Program Manager, Wildlife and Terrestrial Ecosystems, RMRS, USDA FS, Oct 2010 to present.
Research Ecologist, USDA Forest Service, Rocky Mountain Research Station, June 2005 to Oct 2010.
Adjunct Faculty, University of Montana, Missoula, MT, April 2012 to present.
Faculty Affiliate, University of Montana, Missoula, MT, September 2005 to April 2012.
Wildlife Biologist, USDA Forest Service, Rocky Mountain Research Station, September 1995 to June 2005.
Research Assistant, University of Montana, September 1994 to September 1995.
Private Contractor, USDA Forest Service, Rocky Mountain Research Station, 1995.
Biological Technician, Glacier National Park, 1991 to 1994.
Teaching Assistant, University of Montana, 1991 to 1993.
Biological Technician, Conservation Biology Project, UCLA, stationed in Baja Mexico, Sept. to Dec. 1990.
GIS Technician, Glacier National Park, June to September 1990.
Biological Technician, Wolf Ecology Project, University of Montana, 1988 to 1989.

International Experience

I lead a team of international scientists examining the biogeographic aspects of invasion by studying multiple plant species in their native range (Turkey) and two invaded ranges (Argentina and Montana). 

Hobbies

Birding, bow hunting elk, naturalizing, exploring the desert, landscaping, gardening