US Forest Service Research & Development
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  • 1400 Independence Ave., SW
  • Washington, D.C. 20250-0003
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Dean E. Pearson

Research Ecologist
800 East Beckwith Avenue
United States

Phone: 406-542-4159
Contact Dean E. Pearson

Curriculum vitae (237 KB PDF)

Current Research

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:

Invasive plant impact rankings for intermountain bluebunch wheatgrass:

Adjunct Faculty, Organismal Biology Ecology Evolution, University of Montana:

Research Interests

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.

Past Research

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

  • Best Scientific Publication Award, 2019
    Best Scientific Publication Award, USDA Forest Service, Rocky Mountain Research Station, Oct 2019, for the publication: Pearson, D.E., Y.K. Ortega, J. Runyon, and J. Butler. 2016. Secondary invasion: the bane of weed management. Biological Conservation
  • 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 Chief’s 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 Chief’s 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


Research Highlights


Invasive Plant Erodes Bird Song Diversity via Food Chain Effects

Although plant invaders are known for their negative effects on natural systems, the extent of these impacts is often unknown. Forest Service s ...


Invasiveness and Impact of 48 Exotic Plant Species in Native Grasslands

This study quantified and ranked invasiveness and impact for 48 exotic plant species based on surveys over 20,000 square kilometers (12,427 squa ...


The Bane of Weed Management: Secondary Invasions

Weed management can result in unintentional secondary invasion: an increase in non-target exotics following efforts to suppress targeted invasiv ...


The tortoise and the hare: Can the slow native plant win?

It has been suggested that exotic plants will be more successful than native plant species as a result of climate change. This is because exotic ...


Why Do the Exotics Beat the Natives: Where Is the Home-Team Advantage

New research sets forth a framework for understanding why exotic plants invade and how to fight the invasions


Last updated on : 09/13/2021