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Brenda Grewell

Research Ecologist

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(530) 752-0166

Area of Expertise:

Research Ecologist


Ph.D., University of California Davis, 2004


Work Experience:   

Research Ecologist, USDA/ARS, Invasive Species and Pollinator Health Research Unit, Davis, CA, 2004 to present

Fulbright Scholar in Botany, Faculty of Biological Sciences, Dept. of Ecology & Hydrobiology, University of South Bohemia, Czech Republic, 2003.

Post-graduate Researcher, University of California, Davis and Bodega Marine Laboratory. Sacramento – San Joaquin Delta – San Francisco Estuary Ecosystem Restoration Program, tidal wetland ecology and endangered plant recovery, 1998-2002.

Sr. Environmental Scientist (Wetland Ecologist/Aquatic Botanist), California Department of Water Resources, Environmental Services Office, Suisun Marsh Program, 1989-1998.



Research Focus:

Our research team investigates aspects of plant biology and ecology, and the ecology of biological invasions that contribute to the development of ecologically-based and environmentally benign management strategies for invasive aquatic, wetland and riparian plants in the Pacific West that will reduce undesired impacts on non-target organisms and the environment. Overarching objectives of this research are to conduct research to understand the biogeography of invasive plant species and the ecology of invaded systems at relevant spatial scales to solve critically important invasive weed problems. We aim to support recovery of impacted native species, plant communities and watersheds, and to develop ecologically-based strategies for invasive plant management that are integrated with strategies for ecological restoration.


Current research includes focus on the following:  


  1. Conduct biosystematics studies including morphological, cytological and genetic differentiations to provide accurate identification of confusing and highly invasive Ludwigia taxa to support development of integrated management including biological control for these highly variable-looking plant species. Studies are underway in Pacific Coast states and Florida.
  2. Assess physiological and morphological traits that influence the survival, colonization, growth and competitive ability of invasive plant species under changing environmental conditions to inform invasive species risk assessments and predict feedbacks on community dynamics and ecosystem processes. For example, we are assessing how ploidy level and resource availability affect regeneration and colonization strategies of invasive water primroses, including germination and seed bank dynamics and regeneration from clonal bud banks.
  3. Identify factors determining impacts of invasive plant species on desirable plant communities and ecosystems, and illuminate factors contributing to context-specificity of invasions and their impacts.
  4. Evaluate the role of phenotypic plasticity, ploidy level and genetic differentiation on the capacity of invasive aquatic plants/populations to maintain fitness in response to environmental changes. For example, we are studying the effects on increasing salinity and inundation regimes with sea level rise on invasive cordgrasses and their hybrids, and on yellow flag iris in estuarine ecosystems of the Sacramento – San Joaquin Delta and San Francisco Estuary.  
  5. Evaluate the influence of hydrology and water management on dispersal, propagule pressure and establishment of invasive Ludwigia hexapetala in the Russian River Watershed, and identify river reach-scale strategies for restoring native plant communities.  


*Info about my research team:

Current lab members: Caryn Joy Futrell, M.S.; Jessica Drost, B.S.

2017 Lab Alumni: Dr. Meghan Skaer Thomason; Christopher McCort, M.S.; Ann Le, B.S.; Denise Castro, undergraduate associate; Mayra Huerta, undergraduate student associate. 

Principal collaborators: Dr. Rebecca E. Drenovsky, John Carrol University, Dr. Michael Netherland, US Army Corps Aquatic Plant Control Research Program/University of Florida; Dr. John Gaskin, USDA-ARS Sidney, MT; Dr. Gabrielle Thiébaut, Dr. Morgane Gillard, University of Rennes 1, Rennes, France; Dr. Jesús Castillo, Blanca Gallego-Tevar, Ph.D. Candidate, University of Seville, Spain; Dr. Christine Whitcraft, California State University-Long Beach; Dr. Peter Hoch, Missouri Botanical Garden Research Herbarium.