October 22, 2012

The Honorable Tom Vilsack 

Secretary, U.S. Department of Agriculture 

The Honorable Steven Chu

Secretary, U.S. Department of Energy

The Honorable Leon Panetta 

Secretary, U.S. Department of Defense

The Honorable Lisa Jackson 

Administrator, U.S. Environmental 

Protection Agency 

The Honorable Ray LaHood

Secretary, U.S. Department of 

Transportation

Dear Secretary Vilsack, Secretary Chu, Secretary Panetta, Administrator Jackson, and Secretary 

LaHood,

As scientists in the fields of ecology, wildlife biology, forestry, and natural resources, we are 

writing to bring your attention to the importance of working proactively to prevent potential 

ecological and economic damages associated with the potential spread of invasive bioenergy 

feedstocks. While we appreciate the steps that federal agencies have made to identify and 

promote renewable energy sources and to invest in second and third generation sources of 

bioenergy, we strongly encourage you to consider the invasive potential of all novel feedstock 

species, cultivars, and hybrids before providing incentives leading to their cultivation. 

Studies have shown that some of the plants considered most promising in terms of bioenergy 

capacity may actually be highly invasive and potentially harmful to native species and 

ecosystems.1,2,3,4In fact, many of the characteristics that make a plant appealing as an ideal 

source of biomass such as ease of establishment, rapid growth, resistance to pests and diseases, 

and low input requirements, are the same characteristics that make a plant more likely to become 

invasive.5,6 According to the non-federal members of Invasive Species Advisory Committee that 

provide independent advice to the National Invasive Species Council, “Absent strategic 

mitigation efforts, there is substantial risk that some biofuels crops will escape cultivation and 

cause socio-economic and/or ecological harm.”7

Many of today’s most problematic invasive plants – from kudzu to purple loosestrife – were

intentionally imported and released into the environment for horticultural, agricultural, 

conservation, and forestry purposes. These invasive species already cost billions of dollars a year 

in the United States8and are one of the primary threats to North America’s native species and 

ecosystems. It is imperative that we learn from our past mistakes by preventing intentional 

introduction of energy crops that may create the next invasive species catastrophe – particularly 

when introductions are funded by taxpayer dollars.

Under Executive Order 13112, a federal agency cannot “authorize, fund, or carry out actions that 

it believes are likely to cause or promote the introduction or spread of invasive species in the 
United States or elsewhere unless, pursuant to guidelines that it has prescribed, the agency has 

determined and made public its determination that the benefits of such actions clearly outweigh 

the potential harm caused by invasive species; and that all feasible and prudent measures to 

minimize risk of harm will be taken in conjunction with the actions.” 

To ensure ongoing compliance with the Executive Order and to prevent unintended 

consequences from the promotion of non-native and modified plants, algae, and microorganisms, 

we therefore request that federal agencies clearly assess the invasion risk of bioenergy feedstocks 

(including hybrids, varieties, genetically modified organisms, and cultivars) before these 

feedstocks can be eligible for federal incentives leading to their cultivation (through mandates, 

purchases, research grants, loans, and other means). Those species that may become invasive in 

the United States should be ineligible for incentives, unless the risk is low and, at a minimum, 

prudent measures are available and mandated to reduce the invasion risk and potential for harm.

Tools for assessing the invasiveness of plant species and cultivars are widely available, including 

USDA APHIS’s newly revamped weed risk assessment.

9

The National Invasive Species Council 

is best suited to coordinate this assessment process. 

A thoughtful, consistent, proactive approach to sustainable bioenergy production that avoids 

potentially invasive feedstocks, while encouraging the development and implementation of new 

energy crops to meet U.S. renewable energy goals, would demonstrate wise stewardship of 

federal funds and serve to benefit the agencies in the long run. By assessing and reducing risks 

up front, we can minimize the potential for bioenergy crops that are promoted with taxpayer 

dollars to become invasive and cause harm to natural ecosystems. It is much cheaper and easier 

to take the steps to prevent an invasive escape than it is to deal with it after it has occurred.

Signed,

Richard N. Mack, Ph.D.

Washington State University

Pullman, WA

Dale Gawlik, Ph.D., Wildlife Sciences 

President, FL Chapter of the Wildlife Society

Florida Atlantic University

Boca Raton, FL

Joseph M. DiTomaso, Ph.D.

University of California

Davis, CA

Bruce Robertson, Ph.D.

Bard College

Annandale-on-Hudson, NY

James Miller, Ph.D.

Professor Emeritus

Mississippi State University

Starkville, MS

Scott L. Collins, Ph.D.

President, Ecological Society of America

Washington, DC
S. Raghu, Ph.D.

Stuttgart, AR

Lee Van Wychen, Ph.D.

Weed Science Society of America

Alexandria, VA

Dean Urban, Ph.D.

Duke University

Durham, NC

Adam M. Lambert, Ph.D.

Santa Barbara, CA

Elizabeth L. Middleton, Ph.D.

Missouri Department of Conservation

Clinton, MO

Kenneth Langeland, Ph.D.

Professor, University of Florida IFAS, 

Agronomy Department and Center for Aquatic 

and Invasive Plants

Gainesville, FL

Catherine A. McGlynn, Ph.D.

Northeast Illinois Invasive Plant Partnership

Chicago, IL

Donald C. Jackson, Ph.D., Fisheries

Mississippi State University

Mississippi State, MS

Douglas B. Inkley, Ph.D.

National Wildlife Federation

Reston, VA

Doria R Gordon, Ph.D.

The Nature Conservancy

Gainesville, FL

Emma Hampton, Ph.D., Zoology

University of Texas at Austin

Austin, TX

Rakesh S. Chandran, Ph.D. 

Extension Weed Specialist & Professor

West Virginia University

Morgantown, WV

Joseph Sirotnak, Ph.D., Ecology

Big Bend National Park

Big Bend, Texas

Loretta Battaglia, Ph.D., Ecology

Southern Illinois University

Carbondale, IL

Dawn Lawson, Ph.D., Ecology

San Diego, California

Matthew Olson, Ph.D., Forest Resources

West Plains, MO

F. Bryan Pickett, Ph.D., Genetics

Chicago, IL

Lizbeth Seebacher, Ph.D., Invasive Species 

Biology

Washington State Department of Ecology

Lacey, WA

Lowell Pritchard Jr., Ph.D., Natural Resource 

Economics

Creation Care Inc.

Decatur, GA

Jo Anna Hebberger, Ph.D., Plant Ecology

Des Moines, IA

Alton Kinlaw, Ph.D., R.Ph.

Indiana University Health

Indianapolis, IN

Thomas Eubank, Ph.D., Weed Science

Mississippi State University

Stoneville, MS
William Faber, Ph.D., Wildlife Ecology

Central Lakes College

Brainerd, MN

Daniel C. Abel, Ph.D.

Coastal Carolina University

Conway, SC

Sarah Ward, Ph.D.

Colorado State University

Fort Collins, CO

Leonard Bull, Ph.D.

Cornell University

New Haven, VT

Antonio DiTommaso, Ph.D.

Cornell University

Ithaca, NY

John J. Jachetta, Ph.D.

Dow AgroSciences LLC

Indianapolis, IN

Sam Pearsall, Ph.D.

Environmental Defense Fund

Raleigh, NC

Margaret K. Thayer, Ph.D.

Field Museum of Natural History

Chicago, IL

Frank Powell, Ph.D.

Furman University

Seneca, SC

Daniel R. Ludwig, Ph.D.

Illinois Department of Natural Resources

Bartlett, IL

Heather L Reynolds, Ph.D.

Indiana University

Bloomington, IN

Vicky Meretsky, Ph.D.

Indiana University

Bloomington, IN

Angie Shelton, Ph.D.

Indiana University

Bloomington, IN

Chris Habeck, Ph.D.

Kutztown University

Kutztown, PA

Reuben Keller, Ph.D.

Loyola University, Chicago

Chicago, IL

Victor Maddox, Ph.D.

Mississippi Cooperative Weed Management 

Area

Mississippi State, MS

David R. Shaw, Ph.D.

Mississippi State University

Miss. State, MS

John D. Byrd, Jr., Ph.D.

Mississippi State University

Mississippi State, MS

Bruce A. Stein, Ph.D.

National Wildlife Federation

Washington, DC

James T. Green, Jr., Ph.D.

North Carolina State University

Raleigh, NC

Kirk Howatt, Ph.D.

North Dakota State University

Fargo, ND

Daniel A. Ball, Ph.D.

Oregon State University

Pendleton, OR
Carol Mallory-Smith, Ph.D.

Oregon State University

Corvallis, OR

Thomas Wassmer, Ph.D.

Siena Heights University

Adrian, MI

William R. Eddleman, Ph.D.

Southeast Missouri State University

Cape Girardeau, MO

Christopher E. Comer, Ph.D.

Stephen F. Austin State University

Nacogdoches, TX

Li Kui, Ph.D.

SUNY-ESF

Syracuse, NY

Brian D. Carver, Ph.D.

Tennessee Technological University

Cookeville, TN

James R. Manhart, Ph.D.

Texas A&M University

College Station, TX

Scott Senseman, Ph.D.

Texas A&M University

College Station, TX

Peter Kareiva, Ph.D.

The Nature Conservancy

Seattle, WA

Kelly Lyons, Ph.D.

Trinity University

San Antonio, TX

Jodie S Holt, Ph.D.

University of California

Riverside, CA

Betsy Von Holle, Ph.D.

University of Central Florida

Orlando, FL

Vicki Jackson, Ph.D.

University of Central Missouri

Warrensburg, MO

Sarah Bois, Ph.D.

University of Connecticut

Storrs, CT

Mark VanGessel, Ph.D.

University of Delaware

Georgetown, DE

William A Overholt, Ph.D.

University of Florida

Fort Pierce, FL

Lyn Gettys, Ph.D.

University of Florida

Davie, FL

Jason Evans, Ph.D.

University of Georgia

Athens, GA

Donn Shilling, Ph.D.

University of Georgia

Athens, GA

Lauren Quinn, Ph.D.

University of Illinois

Urbana, IL

Peter Alpert, Ph.D.

University of Massachusetts, Amherst

Amherst, MA

Catherine Badgley, Ph.D.

University of Michigan

Ann Arbor, MI
L. Jack Lyon, Ph.D.

University of Michigan

Missoula, MT

Larry G. Visser, Ph.D.

University of Michigan

Ann Arbor, MI

Johannes Foufopoulos, Ph.D.

University of Michigan

Ann Arbor, MI

Michael R. Moore, Ph.D.

University of Michigan

Ann Arbor, MI

Ivette Perfecto, Ph.D.

University of Michigan

Ann Arbor, MI

William S. Currie, Ph.D.

University of Michigan

Ann Arbor, MI

Daniel Tufford, Ph.D.

University of South Carolina

Columbia, SC

Norma Fowler, Ph.D.

University of Texas

Austin, TX

Sarah Reichard, Ph.D.

University of Washington Botanic Gardens

Seattle, WA

Joy B. Zedler, Ph.D.

University of Wisconsin

Madison, WI

Philip A. Fay, Ph.D.

USDA-ARS

Temple, TX

John Fike, Ph.D.

Virginia Tech

Blacksburg, VA

Paul E. Bartelt, Ph.D.

Waldorf College

Forest City, IA

M. Jahi Chappell, Ph.D.

Washington State University, Vancouver

Vancouver, WA

Kashka Kubzdela, Ph.D.

Oakton, VA

Charles P. Nicholson, Ph.D.

Norris, TN

Jeff Levengood, Ph.D.

Champaign, IL

Jean O'Neil, Ph.D.

W. Hatfield, MA

Ron Carroll, Ph.D.

Athens, GA

Ruth Douglas, Ph.D.

Charlottesville, VA

Matt Bahm, Ph.D.

Spokane, WA

Lesli Hoey, Ph.D.

Ann Arbor, MI

Robin Goodloe, Ph.D.

Athens, GA

David L. Davidson, Ph.D.

San Antonio, TX

Paul H. Meredith, Ph.D.

Victoria, TX
Mary R. Meredith, Ph.D.

Victoria, TX

John Tirpak, Ph.D.

Lafayette, LA Kathryn Kavanagh, Ph.D.

Austin, TX

Robert Kamper, Ph.D.

Round Rock, TX

Rachel Schultz, Ph.D.

Plattsburgh, NY

Jeanne Jones, Ph.D.

Louisville, MS

Susan P. Rupp, Ph.D.

Brookings, SD

Georgianne Moore, Ph.D.

College Station, TX

Jill Schroeder, Ph.D.

Las Cruces, NM

Iñigo Granzow-de la Cerda, Ph.D.

Ann Arbor, MI

Jonathan Ambrose, Ph.D.

Watkinsville, GA

Judith Breland, Ph.D.

Wiggins, MS

Rodney Lym, Ph.D.

Fargo, ND

Barry J. Brecke, Ph.D.

Milton, FL

Roger E. Gast, Ph.D.

Zionsville, IN

Jessica Hite, Ph.D. Candidate

Indiana University

Bloomington, IN

Bryan Tarbox, Ph.D. Candidate

Gainesville, FL

Sarah Fritts, Ph.D. Candidate

North Carolina State University

Raleigh, NC

Heidi L Springborn

Natural Resources Technican

Wisconsin Department of Natural Resources

Green Bay, WI

Jenn Truong, MNR

Fairfax, VA

Tamara Johnson, MNR GA

Susan Kenzle, MLA

American Society of Landscape Architects

Austin, TX

Roy B. Mann, MLA

Harvard Graduate School of Design

Cambridge, MA

Jason Hodges, MLA

Texas Tech University

Lubbock, TX

Sam Rogers, MLA

University of Tennessee

Knoxville, TN

Darcy Nuffer, MLA

University of Texas

Austin, TX

Ariel Shaw, MLA

San Francisco, CA
Doug Johnson, M.S., M.A.

California Invasive Plant Council

Berkeley, CA

Kathy Schwager, M.S., Ecology

Certified Ecologist

Patchogue, NY

Eamonn Leonard, M.S., Plant Ecology

Georgia Department of Natural Resources

Brunswick, GA

Frank Hassler, M.S., Forestry

Good Oak Ecological Services

Madison, WI

Steven C. Garske, M.S., Plant Ecology

Great Lakes Indian Fish & Wildlife 

Commission

Odanah, WI

Patricia Clifford, M.S., Natural Resource 

Planning

Hawaii-Pacific Weed Risk Assessment

Honolulu, HI

Aaron Yetter, M.S., Zoology

Illinois Natural History Survey

Havana, IL

Shawna L. Bautista, M.S., Zoology & 

Physiology

Invasive Plant Program Manager

USDA Forest Service

Portland, OR

Donna Beliech, M.S., Horticulture 

President of the MS Assn. of Co. Ag. Agents 

(MACAA)

Mississippi State University

Brandon, MS

Susan Farrington, M.S., Forest Ecology

Missouri Department of Conservation

West Plains, MO

Aaron Stevenson, M.S., Forest Ecology

Missouri Department of Conservation

West Plains, MO

Timothy Banek, M.S., Biology

Missouri Department of Conservation

Jefferson City, MO

Terry L. Goldsby, M.S., Botany

Northwestern State University of Louisiana

Guntersville, AL

Lindsey Wise, M.S., Ecology

Portland State University

Portland, OR

Carole Gernes, M.S., Biology

Ramsey County Cooperative Weed 

Management Area

Little Canada, MN

Pete Jackson, M.S., Biology

U.S. EPA

Chicago, IL

Jill Hardiman, M.S., Fish and Wildlife 

Biology

United States Geological Survey

Cook, WA

Jennifer J Buck, M.S., Plant Science

University of California, Davis

Nevada City, CA

Kandarpa Cousineau, M.S., Inorganic 

Chemistry

University of Michigan

Los Angeles, CA
Ted Seiler, M.S., Wildlife Biology

University of Missouri

Macon, MO

Leslie Harman, M.S., Geology

University of Missouri

Columbia, MO

Pat Parr, M.S., Ecology

University of Tennessee

Oak Ridge, TN

Glen Buckner, M.S., Ecology and 

Environmental Science

Will County Forest Preserve

Joliet, IL

Timothy Burr, M.S., Zoology

Poway, CA

Karen Viste-Sparkman, M.S., Wildlife 

Science

Des Moines, IA

Sylvia Copeland, M.S., Wildlife Science

Nampa, ID

Kristen Aaltonen, M.S., Wildlife Ecology and 

Conservation

Austin, TX

Lowell H. Suring, M.S., Wildlife Ecology

Suring, WI

Chris Newbold, M.S., Wildlife Biology

Columbia, MO

Mary Ellen Kustin, M.S., Sustainable 

Development and Conservation Biology

Riverdale, MD

Reed Sanderson, M.S., Range Management

Green Valley, AZ

Elizabeth Colket, M.S., Range Ecology and 

Management

Boise, Idaho

Sandra Birnbaum, M.S., Population & 

Conservation Biology

Austin, TX

Alison Robbins, M.S., D.V.M.

Boston, MA

A. Strong, M.S., Botany

Austin, TX

Leon Bates, M.S., Botany

Benton, TN

Darby Niswonger, M.S., Biology

Chillicothe, MO

Bill McGuire, M.S., Biology

Jefferson City, MO

Charles Kowaleski, M.S., Biology

Salado, Texas

Karen Kreil, M.S., Biology

Bismarck, ND

Alexandra Wrobel, M.S., Applied Ecology

Ashland, WI

Rebecca Swadek, M.S.

Carrollton, TX

Michael Daab, M.S.

Champaign County Forest Preserve

Champaign, IL

Vanelle Peterson, M.S.

Dow AgroSciences LLC

Mulino, OR
Lindsay D. Leverett, M.S.

Duke University

Durham, NC

David Kyler, M.S.

Executive Director, Center for a Sustainable 

Coast

Saint Simons Island, GA

Chris Buddenhagen, M.S.

Florida State University

Tallahassee, FL

Chris Lockhart, M.S.

Habitat Specialists, Inc.

Boynton Beach, FL

Charles Chimera, M.S.

Hawaii-Pacific Weed Risk Assessment

Makawao, HI

Ward Bloodworth, M.S.

Mississippi Ag Industry Council

Madison, MS

Amanda Walker, M.S.

Mississippi State University

Monticello, MS

Michael Cove, M.S.

North Carolina State University

Raleigh, NC

David Watts, M.S.

Texas A&M University

State College, PA

Jack LeClair, M.S.

Texas A&M University-Kingsville

Kingsville, TX

Jessica Strickland, M.S.

Texas State University

San Marcos, TX

Michael Lusk, M.S.

The Wildlife Society

Crystal River, FL

Kai Umeda, M.S.

University of Arizona

Phoenix, AZ

Rob Proulx, M.S.

University of Minnesota

Crookston, MN

Jim Eckberg, M.S.

University of Minnesota

Saint Paul, MN

Merel R. Black, M.S.

University of Wisconsin- Stevens Point

Stevens Point, WI

Kevin Hurley, M.S.

University of Wyoming

Laramie, WY

Matthew Kaproth, M.S.

West Virginia University

Burlington, VT

Vern Holm, M.S.

Western Invasives Network

McMinnville, OR

Theodore Cochrane, M.S.

Wisconsin State Herbarium

Madison, WI

Gerry Steinauer, M.S.

Aurora, NE

Carey Strobel, M.S.

Austwell, TX

Janene Lichtenberg, M.S.

Polson, MT
Mike Livingston, M.S.

Prosser, WA

Martha Gruelle, M.S.

Detroit, MI

Rebecca Schillo, M.S.

Chicago, IL

Landon Vine, M.S.

Denver, CO

Bridget Collins, M.S.

Washington, DC

Kenny Ribbeck, M.S.

Baton Rouge, LA

Fan Li, M.S.

Houston, TX

Steve Winters, M.Ag.

Mississippi State University

Grenada, MS

Monique De Vries, M.Ag.

New Mexico State University

San Antonio, TX

Eric David Boyda

Appalachian Ohio Weed Control Partnership

Pedro, OH

Aviva Glaser, M.S., Conservation Biology

Baltimore, MD

Betty Mading

Lady Bird Johnson Wildflower Center

Austin, TX

Robert Clancy

Michigan Department of Natural Resources

Lansing, MI

Kenneth Calcote

Mississippi Department of Agriculture & 

Commerce

Mississippi State, MS

Dan Drees

National Park Service

Van Buren, MO

Benjy Strope, 

NC Wildlife Resources Commission

White Oak, NC

Greg J. Wall, 

President, Mississippi Vegetation 

Management Association 

Helena Chemical Company

Sturgis, MS

CC: Heather Zichal, Deputy Assistant to the President for Energy and Climate Change

Lori Williams, Executive Director of the National Invasive Species Council

Jeffrey Zients, Acting Director of the Office of Management and Budget

 

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Adding biofuels to the invasive species fire? Science 313: 1742.
 

2 DiTomaso, J.M., J.M. Barney, and A.M. Fox. 2007. Biofuel feedstocks: the risk of future invasions. Council for 

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3 Barney, J.N. and J.M. DiTomaso. 2008 Nonnative species and bioenergy: Are we cultivating the next invader? 

BioScience 58: 64-70.

4 Low, T., C. Booth, and A. Sheppard. 2011. Weedy biofuels: What can be done? Current Opinion in Environmental 

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5 Witt, A. 2011. Biofuels as Invasive Species. CABI Expert White Paper Series on Biofuels.

6 Raghu, et al. 2006.

7

Invasive Species Advisory Committee (ISAC). 2009. Biofuels: Cultivating Energy, not Invasive Species.

8

Pimentel, D., L. Lach, R. Zuniga, and D. Morrison. 2000. Environmental and economic costs associated with nonindigenous species in the United States. BioScience 50: 53-65.

9 Koop, AL, L Fowler, LP Newton, and BP Caton. 2011. Development and validation of a weed screening tool for 

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