Dean E. Pearson
800 East Beckwith Avenue
Contact Dean E. Pearson
Dr. Pearson's current research focus is applying community ecology to address conservation and management challenges in general and the problem of biological invasions (introduced pest species) in particular. He leads a small team that is tackling the three key components of the invasion problem: 1) understanding the causes of invasion by conducting international research on many plant species in their native and introduced ranges to determine how the introduction of organisms to new ranges creates pest species; 2) studying invader impacts in the introduced range to identifying mitigation targets and strategies; and 3) quantifying the efficacy of management tools (e.g., biological control, herbicides, restoration strategies) and refining their applications for mitigating invader impacts.
Ecology and management of invasive species: http://www.fs.fed.us/rm/wildlife-terrestrial/invasive-species/
Invasive plant impact rankings for intermountain bluebunch wheatgrass: http://ow.ly/PQKz9
Adjunct Faculty, Organismal Biology Ecology Evolution, University of Montana: http://hs.umt.edu/dbs/grad-programs/obe/faculty.php?id=1063
Dean Pearson's primary research interest is to advance community ecology through studies of biological invasions and to use this information to improve invasive species management. Biological invasions serve as grand natural experiments that provide unique opportunities to view the processes that structure ecological communities. Even in the most recently assembled natural communities organisms have had hundreds or thousands of years to interact and sort themselves into the modern assemblages we see. This makes it very challenging to identify the relative roles of competition, predation, parasitism, resource availability, etc. in structuring extant communities. However, with biological invasions, it is possible to observe these processes in real time as a novel organism invades, establishes, and dominates (in the case of strong invaders) a new assemblage. It is also possible to see how the assemblage finally settles into a new equilibrium state as the invader's dominance wanes through the ecological and evolutionary adaptation of the community to its presence. Newly hypothesized understandings of these processes can then be tested in the context of directed community assembly through the applied largescale natural experiments that are attempts to manage the invasion problem, for example, classical biological control - the intentional introduction of exotic organisms to manage invasions. Thus, biological invasions offer an opportunity to advance understandings of community ecology that can in turn be tested by applying these understandings to the management of the invasives problem.
Dean's prior research focused on wildlife biology, studying wildlife-habitat relationships and techniques for wildlife studies.
Why This Research is Important
Biological invasions present the second greatest threat to natural ecosystems and the services they provide next only to actual land transformation. Exotic species invasions cost the United States 120-140 billion dollars per year in revenue losses and mitigation costs. Management of this problem has been particuarly challenging due to a lack of understanding of the fundamental processes underlying invasion. My research attempts to better understand the causes and consequences of invasion and the efficacy of current managmen tools in order to better guide management approaches toward more effective mitigation. Success in these efforts offers tremendous benefits in terms of US revenues and stability of ecosystem services.
- University of Montana, Ph.D. Organismal Biology and Ecology 2005
- University of Montana, M.A.S. Zoology 1995
- University of Montana, B.S. Wildlife Biology 1992
Awards & Recognition
- Visionary Science Publication Award, 2013
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 Forest System Invasive Species Program Award, 2012
March 2012, 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.
- National Academy of Sciences, Kavli Fellow Recipient, 5 November 2010., 2010
- Deputy Chiefs Early Career Scientist Award. , 2009
This honor was awarded in recognition of significant contributions to the fields of biological control, invasive species ecology, and wildlife biology.
- Presidential Early Career Award for Science and Engineering (PECASE). , 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 Chiefs Early Career Scientist Award. , 2009
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.
Featured Publications & Products
- Pearson, Dean E.; Ortega, Yvette K.; Eren, Ozkan ; Hierro, Jose L. 2018. Community assembly theory as a framework for biological invasions.
- Pearson, Dean E.; Ortega, Yvette K.; Villarreal, Diego ; Lekberg, Ylva ; Cock, Marina C.; Eren, Ozkan ; Hierro, Jose L. 2018. The fluctuating resource hypothesis explains invasibility, but not exotic advantage following disturbance.
- Pearson, Dean E.; Eren, Ozkan ; Ortega, Yvette K.; Villarreal, Diego ; Senturk, Muhyettin ; Miguel, M. Florencia; Weinzettel, C. Miguel; Prina, Anibal ; Hierro, Jose L. 2018. Are invasive plants more abundant in the introduced versus native range.
- Pearson, Dean E.; Ortega, Yvette K.; Maron, John L. 2017. The tortoise and the hare: Reducing resource availability shifts competitive balance between plant species.
- Pearson, Dean E.; Valliant, Morgan ; Carlson, Chris ; Thelen, Giles C.; Ortega, Yvette K.; Orrock, John L.; Madsen, Matthew D. 2019. Spicing up restoration: Can chili peppers improve restoration seeding by reducing seed predation.
- Pearson, Dean E.; Callaway, Ragan M.; Maron, John L. 2011. Biotic resistance via granivory: Establishment by invasive, naturalized, and native asters reflects generalist preference.
- Ortega, Yvette K.; Pearson, Dean E. 2005. Weak vs. strong invaders of natural plant communities: Assessing invasibility and impact.
- Pearson, Dean E.; Ortega, Yvette K.; Eren, Ozkan; Hierro, Jose L. 2015. Quantifying "apparent" impact and distinguishing impact from invasiveness in multispecies plant invasions.
- Pearson, Dean E.; Ortega, Yvette K.; Runyon, Justin B.; Butler, Jack L. 2016. Secondary invasion: The bane of weed management.
- Pearson, Dean E.; Ortega, Yvette K.; Sears, Samantha J. 2012. Darwin's naturalization hypothesis up-close: Intermountain grassland invaders differ morphologically and phenologically from native community dominants.
- Mayfield, Albert E., II.; Seybold, Steven J.; Haag, Wendell R.; Johnson, M. Tracy; Kerns, Becky K.; Kilgo, John C.; Larkin, Daniel J.; Lucardi, Rima D.; Moltzan, Bruce D.; Pearson, Dean E.; Rothlisberger, John D.; Schardt, Jeffrey D.; Schwartz, Michael K.; Young, Michael K. 2021. Impacts of Invasive Species in Terrestrial and Aquatic Systems in the United States.
- Mayfield, Albert (Bud); Seybold, Steven; Haag, Wendell; Johnson, Tracy; Kerns, Becky; Kilgo, John; Larkin, Daniel; Lucardi, Rima; Moltzan, Bruce; Pearson, Dean; Rothlisberger, John; Schardt, John; Schwartz, Michael; Young, Michael. 2021. Impacts of invasive species in terrestrial and aquatic systems in the United States..
- Poland, Therese M.; Juzwik, Jennifer ; Rowley, Allen ; Huebner, Cynthia D.; Kilgo, John C.; Lopez, Vanessa M.; Olson, Deanna H.; Pearson, Dean E.; Progar, Robert ; Rabaglia, Robert ; Rothlisberger, John D.; Runyon, Justin ; Sing, Sharlene E. 2021. Management of Landscapes for Established Invasive Species.
- Jang, Woongsoon ; Crotteau, Justin S.; Ortega, Yvette K.; Hood, Sharon M.; Keyes, Christopher R.; Pearson, Dean E.; Lutes, Duncan C.; Sala, Anna . 2021. Native and non-native understory vegetation responses to restoration treatments in a dry conifer forest over 23 years.
- Koch, Jennifer ; Pearson, Dean E.; Huebner, Cynthia D.; Young, Michael K.; Sniezko, Richard A. 2021. Restoration of Landscapes and Habitats Affected by Established Invasive Species.
- Liebhold, Andrew M.; Campbell, Faith T.; Gordon, Doria R.; Guo, Qinfeng ; Havill, Nathan ; Kinder, Bradley ; MacKenzie, Richard ; Lance, David R.; Pearson, Dean E.; Sing, Sharlene E.; Warziniack, Travis ; Venette, Robert C.; Yemshanov, Denys . 2021. The Role of International Cooperation in Invasive Species Research.
- Taylor, Justin B.; Cass, Kristina L.; Armond, David N.; Madsen, Matthew D.; Pearson, Dean E.; St. Clair, Samuel B. 2020. Deterring rodent seed-predation using seed-coating technologies.
- Gaskin, John F.; Espeland, Erin ; Johnson, Casey D.; Larson, Diane L.; Mangold, Jane M.; McGee, Rachel A.; Milner, Chuck ; Paudel, Shishir ; Pearson, Dean E.; Perkins, Lora B.; Prosser, Chadley W.; Runyon, Justin B.; Sing, Sharlene E.; Sylvain, Zachary A.; Symstad, Amy J.; Tekiela, Daniel R. 2020. Managing invasive plants on Great Plains grasslands: A discussion of current challenges.
- Dylewski, Lukasz ; Ortega, Yvette K.; Bogdziewics, Michal ; Pearson, Dean E. 2020. Seed size predicts global effects of small mammal seed predation on plant recruitment.
- Slate, Mandy L.; Durham, Rebecca M.; Pearson, Dean E. 2020. Strategies for restoring the form and function of lichen-moss biocrust communities.
- Slate, Mandy L.; Callaway, Ragan M.; Pearson, Dean E. 2019. Life in interstitial space: Biocrusts inhibit exotic but not native plant establishment in semi-arid grasslands.
- Dylewski, Lukasz ; Myczko, Lukasz ; Pearson, Dean E. 2019. Native generalist consumers interact strongly with seeds of the invasive wild cucumber (Echinocystis lobata).
- Maron, John L.; Hajek, Karyn L.; Hahn, Philip G.; Pearson, Dean E. 2019. Seedling recruitment correlates with seed input across seed sizes: implications for coexistence.
- Ortega, Yvette K.; Valliant, Morgan T.; Pearson, Dean E. 2019. To list or not to list: Using time since invasion to refine impact assessment for an exotic plant proposed as noxious.
- Loehman, Rachel A.; Bentz, Barbara J.; DeNitto, Gregg A.; Keane, Robert E.; Manning, Mary E.; Duncan, Jacob P.; Egan, Joel M.; Jackson, Marcus B.; Kegley, Sandra; Lockman, I. Blakey; Pearson, Dean E.; Powell, James A.; Shelly, Steve; Steed, Brytten E.; Zambino, Paul J. 2018. Effects of climate change on ecological disturbance in the Northern Rockies Region Chapter 8.
- Maron, John L.; Hajek, Karyn L.; Hahn, Philip G.; Pearson, Dean E. 2018. Rodent seed predators and a dominant grass competitor affect coexistence of co-occurring forb species that vary in seed size.
- Pearson, Dean E.; Ortega, Yvette K.; Runyon, Justin ; Butler, Jack L. 2018. Secondary invasion re-redefined: The distinction between invader-facilitated and invader-contingent invasions as subclasses of secondary invasion.
- Larios, Loralee ; Pearson, Dean E.; Maron, John L. 2017. Incorporating the effects of generalist seed predators into plant community theory.
- Smith, Jennifer N.; Emlen, Douglas J.; Pearson, Dean E. 2016. Linking native and invader traits explains native spider population responses to plant invasion.
- Rudgers, Jennifer A.; Fletcher, Rebecca A.; Olivas, Eric; Young, Carolyn A.; Charlton, Nikki D.; Pearson, Dean E.; Maron, John L. 2016. Long term ungulate exclusion reduces fungal symbiont prevalence in native grasslands.
- Maron, John L.; Smith, Alyssa Laney; Ortega, Yvette K.; Pearson, Dean E.; Callaway, Ragan M. 2016. Negative plant-soil feedbacks increase with plant abundance, and are unchanged by competition.
- Pearson, Dean; Ortega, Yvette; Butler, Jack. 2015. Invasive Species Science Update (No. 8).
- Pearson, Dean E.; Icasatti, Nadia S.; Hierro, Jose L.; Bird, Benjamin J. 2014. Are local filters blind to provenance Ant seed predation suppresses exotic plants more than natives.
- Ortega, Yvette K.; Greenwood, Leigh F.; Callaway, Ragan M.; Pearson, Dean E. 2014. Different responses of congeneric consumers to an exotic food resource: Who gets the novel resource prize.
- Connolly, B. M.; Pearson, D. E.; Mack, R. N. 2014. Granivory of invasive, naturalized, and native plants in communities differentially susceptible to invasion.
- Pearson, Dean; Ortega, Yvette; Butler, Jack. 2014. Invasive Species Science Update (No. 7).
- Pearson, D. E.; Hierro, J. L.; Chiuffo, M.; Villarreal, D. 2014. Rodent seed predation as a biotic filter influencing exotic plant abundance and distribution.
- Pinto, Sarah M.; Pearson, Dean E.; Maron, John L. 2014. Seed dispersal is more limiting to grassland diversity than competition or seed predation.
- Maron, John L.; Auge, Harald; Pearson, Dean E.; Korell, Lotte; Hensen, Isabell; Suding, Katharine N.; Stein, Claudia. 2014. Staged invasions across disparate grasslands: Effects of seed provenance, consumers and disturbance on productivity and species richness.
- Pearson, Dean; Ortega, Yvette. 2013. Biogeography of plant invasions.
- Litt, Andrea R.; Pearson, Dean E. 2013. Non-native plants and wildlife in the Intermountain West.
- Ortega, Yvette; Pearson, Dean. 2013. Spotted knapweed: Effects of climate change on the invasiveness and biological control.
- Pearson, Dean E.; Potter, Teal; Maron, John L. 2012. Biotic resistance: Exclusion of native rodent consumers releases populations of a weak invader.
- Zwolak, R.; Pearson, D. E.; Ortega, Y. K.; Crone, E. E. 2012. Mechanisms driving postfire abundance of a generalist mammal.
- Ortega, Yvette K.; Pearson, Dean E.; Waller, Lauren P.; Sturdevant, Nancy J.; Maron, John L. 2012. Population-level compensation impedes biological control of an invasive forb and indirect release of a native grass.
- Maron, John L.; Pearson, Dean E.; Potter, Teal; Ortega, Yvette K. 2012. Seed size and provenance mediate the joint effects of disturbance and seed predation on community assembly.
- Pearson, Dean; Sutherland, Steve; Butler, Jack; Smith, Jane; Sieg, Carolyn. 2011. I. Plants.
- Pearson, Dean; Ortega, Yvette. 2011. Invasive Species Science Update (No. 5).
- Ortega, Yvette K.; Pearson, Dean E. 2011. Long-term effects of weed control with picloram along a gradient of spotted knapweed invasion.
- Pearson, D. E.; Kim, M.; Butler, J. 2011. Rocky Mountain Research Station invasive species visionary white paper.
- Pearson, Dean; Finch, Deborah. 2011. V. Terrestrial vertebrates.
- Maron, John L.; Pearson, Dean E. 2011. Vertebrate predators have minimal cascading effects on plant production or seed predation in an intact grassland ecosystem.
- Maron, John L; Pearson, Dean E.; Fletcher, Robert J., Jr. 2010. Counterintuitive effects of large-scale predator removal on a midlatitude rodent community.
- Ortega, Yvete K.; Pearson, Dean E. 2010. Effects of picloram application on community dominants vary with initial levels of spotted knapweed (Centaurea stoebe) invasion.
- Zwolak, Rafal; Pearson, Dean E.; Ortega, Yvette K.; Crone, Elizabeth E. 2010. Fire and mice: Seed predation moderates fire's influence on conifer recruitment.
- Maron, John L.; Pearson, Dean E.; Hovick, Stephen M.; Carson, Walter P. 2010. Funding needed for assessments of weed biological control.
- Bricker, Mary; Pearson, Dean; Maron, John. 2010. Small-mammal seed predation limits the recruitment and abundance of two perennial grassland forbs.
- Finch, Deborah M.; Pearson, Dean; Wunderle, Joseph; Arendt, Wayne. 2010. Terrestrial animals as invasive species and as species at risk from invasions.
- Pearson, Dean E. 2010. Trait- and density-mediated indirect interactions initiated by an exotic invasive plant autogenic ecosystem engineer.
- Pearson, Dean E. 2009. Biological invasions on oceanic islands: Implications for island ecosystems and avifauna.
- Ortega, Yvette; Pearson, Dean. 2009. Factors influencing plant invasiveness.
- Butler, Jack; Pearson, Dean; Kim, Mee-Sook. 2009. Invasive Species Working Group: Research Summary and Expertise Directory.
- Pearson, Dean E. 2009. Invasive plant architecture alters trophic interactions by changing predator abundance and behavior.
- Pearson, Dean; Ortega, Yvette. 2009. Managing invasive plants in natural areas: Moving beyond weed control.
- Crone, Elizabeth E.; Marler, Marilyn; Pearson, Dean E. 2009. Non-target effects of broadleaf herbicide on a native perennial forb: a demographic framework for assessing and minimizing impacts.
- Zwolak, Rafal; Foresman, Kerry; Crone, Elizabeth; Pearson, Dean; Ortega, Yvette. 2008. Are mice eating up all the pine seeds.
- Ritter, Sharon; Jones, Greg; Watson, Alan; McCaughey, Ward; Harrington, Mick; Zwolak, Rafal; Foresman, Kerry; Crone, Elizabeth; Pearson, Dean; Ortega, Yvette; Loeffler, Dan. 2008. ECO-Report - Finding common ground: Montana Forest Restoration Committee.
- Pearson, Dean E.; Fletcher, Robert J., Jr. 2008. Mitigating exotic impacts: restoring native deer mouse populations elevated by an exotic food subsidy.
- Pearson, Dean. 2008. Understanding the side effects of classical biological control.
- Pearson, Dean E.; Callaway, Ragan M. 2008. Weed biocontrol insects reduce native plant recruitment through second-order apparent competition.
- Pearson, Dean E.; Callaway, Ragan M. 2006. Biological control agents elevate hantavirus by subsidizing deer mouse populations.
- Sturdevant, Nancy; Kegley, Sandy; Ortega, Yvette; Pearson, Dean. 2006. Evaluation of establishment of Cyphocleonus achates and its potential impact on spotted knapweed.
- Shick, Katharine R.; Pearson, Dean E.; Ruggiero, Leonard F. 2006. Forest habitat associations of the golden-mantled ground squirrel: Implications for fuels management.
- Pearson, Dean E. 2005. Biological control is more than just natural enemies.
- Pearson, Dean E.; Callaway, Ragan M. 2005. Indirect nontarget effects of host-specific biological control agents: Implications for biological control.
- Canton-Thompson, Janie; Saveland, Jim; Ritter, Sharon; Ortega, Yvette K; Pearson, Dean F.; Harrington, Mick; Sutherland, Elaine Kennedy; Cook, Clint; Jones, Greg. 2004. ECO-Report - Great issues, great diversions.
- Ortega, Yvette K.; Pearson, Dean E.; McKelvey, Kevin S. 2004. Effects of biological control agents and exotic plant invasion on deer mouse populations.
- Pearson, Dean E.; Callaway, Ragan M. 2004. Response to Thomas et al.: Biocontrol and indirect effects.
- Canton-Thompson, Janie; Patton-Mallory, Marcia; Heald, Sue; Ritter, Sharon; Pfister, Robert D.; Pearson, Dean E.; Ortega, Yvette K.; Watson, Alan; Sutherland, Elaine Kennedy; Jones, Greg. 2003. ECO-Report - The case for research: How it makes a difference to managers.
- Pearson, Dean E.; Callaway, Ragan M. 2003. Indirect effects of host-specific biological control agents.
- Pearson, Dean E.; Ruggiero, Leonard F. 2003. Transect versus grid trapping arrangements for sampling small-mammal communities.
- Pearson, Dean E.; Ortega, Yvette K.; Ruggiero, Leonard F. 2003. Trap-induced mass declines in small mammals: Mass as a population index.
- Pearson, Dean E.; Ortega, Yvette K. 2001. An indirect dispersal pathway for spotted knapweed seeds via deer mice and great-horned owls.
- Ortega, Yvette K.; Pearson, Dean E. 2001. Occurrences of the western skink (Eumeces skiltonianus) in grasslands of western Montana.
- McKelvey, Kevin S.; Pearson, Dean E. 2001. Population estimation with sparse data: The role of estimators versus indices revisited.
- Pearson, Dean E.; Ortega, Yvette K.; McKelvey, Kevin S.; Ruggiero, Leonard F. 2001. Small mammal communities and habitat selection in Northern Rocky Mountain bunchgrass: Implications for exotic plant invasions.
- Pearson, Dean E.; Ruggiero, Leonard F. 2001. Test of the prey-base hypothesis to explain use of red squirrel midden sites by American martens.
- Buskirk, Steven W.; Ruggiero, Leonard F.; Aubry, Keith B.; Pearson, Dean E.; Squires, John R.; McKelvey, Kevin S. 2000. Comparative ecology of lynx in North America Chapter 14.
- Pearson, Dean E. 2000. Evidence of autumn breeding in red squirrels, Tamiasciurus hudsonicus, in western Montana.
- Pearson, Dean E.; McKelvey, Kevin S.; Ruggiero, Leonard F. 2000. Non-target effects of an introduced biological control agent on deer mouse ecology.
- Ruggiero, Len; Pearson, Dean. 2000. Presence/absence as a metric for monitoring vertebrate populations.
- Pearson, Dean E. 2000. Small mammals of the Bitterroot National Forest: Ecological significance and guidelines for management.
- Canton-Thompson, Janie; Smith, Jane Kapler; Jones, Greg; Brown, Perry J.; Arno, Stephen F.; Daniels, Orville L.; Burk, Dale A.; Hardy, Colin C.; Silvieus, Dave; Pflug, Kristi D.; Winhorst, Bruce; Thompson, Brooke; Ortega, Yvette K.; McKelvey, Kevin S.; Thompson, Tom; Pearson, Dean E.; Stewart, Cathy; Sullivan, Janet. 1999. ECO-Report - 1999 Symposium highlights five years of learning.
- Pearson, Dean E. 1999. Small mammals of the Bitterroot National Forest: A literature review and annotated bibliography.
- Ruggiero, Leonard F.; Pearson, Dean E.; Henry, Stephen E. 1998. Characteristics of American marten den sites in Wyoming.
- Foresman, Kerry R.; Pearson, Dean E. 1998. Comparison of proposed survey procedures for detection of forest carnivores.
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