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Dave Mortenson head shot
David Mortensen is professor of weed and applied plant ecology in the College of Agricultural Sciences at Penn State. He is currently serving a five-year term on the board as a farming systems ecotoxicology expert.

Mortensen’s research focuses on the underpinning ecology of food production systems and how specific methods of production enhance or degrade the integrity of those systems. He and his colleagues study practices such as cover cropping, with a particular focus on how such methods enhance ecosystem integrity through weed suppression, soil-quality improvement, and provisioning of pollinators and natural enemies.

His groundbreaking work quantifying the increased reliance on pesticide use in commodity crop production and its deleterious effects on ecosystem integrity has shaped national policy governing crop and pesticide use. He travels around the country speaking with farmers and fellow scientists and has testified about his work in Washington, D.C.

He also has consulted with federal policymakers in the United States and with the European Union. His work has been published in such journals as BioScience, Environmental Toxicology and Chemistry, and Trends in Ecology and Evolution.

Mortensen takes a hybrid approach to his research, involving field experimentation — often with collaborating farmers — and quantitative modeling. Over the course of his 31 years on the faculty at Penn State and at the University of Nebraska, and through his academic training at Duke and North Carolina State universities, he has conducted on-farm research in fields from the coastal plain of North Carolina to the Mississippi River delta, and from Pennsylvania to the heartland of Iowa and Nebraska.

“I can’t over-emphasize the importance of interacting with farmers throughout my career,” he said. ‘It increases dramatically the likelihood that our research remains relevant to the farming community and ecosystem integrity. I’m excited to bring the depth and breadth of my experiences in American farming systems to this role as a scientist on the NOSB.”

Mortensen brings a deep understanding of the inputs used in organic and conventional farming and their ecotoxicological effects on nontarget organisms. Through his research, he has gained detailed knowledge about the intended and unintended consequences of some production practices that may be portrayed as reducing external inputs in farming but that can cause significant risks to worker health and ecosystems.

Mortensen has taught courses on the ecology of agricultural systems, ecologically based pest management, plant ecology, and the urbanization of rural landscapes. He received his academic training in plant ecology at Duke University and in crop science at North Carolina State University. He also chairs a national USDA committee that allocates funds to conduct ecologically based pest-management research and serves on the board of directors of the Pennsylvania Association of Sustainable Agriculture.

Mortensen’s work has been recognized within the College of Agricultural Sciences and beyond. He has received the college’s Alex and Jessie C. Black Award for Excellence in Research, the Weed Science Society of America’s awards for outstanding research and outstanding paper, and the Edward D. Bellis Award in Ecology from Penn State.