Commonly Asked Questions

On this page we've addressed some of the commonly asked questions about this project and hybrid poplars. As a research and Extension team we are constantly learning from the research, experience, and viewpoints of others. If you have information you would like to share with the team, please contact Jeff Jackson at JeffJ@umn.edu.

Project Information

This brief video provides an overview of NRRI's hybrid poplar breeding program: NRRI Hybrid Poplar Program Overview

Are hybrid poplars an invasive species risk?

Hybrid poplars are not an invasive species risk for several reasons. Their seeds are poor quality and have a low viability rate. If seeds would happen to germinate, the seedlings will be easily out-competed by natural vegetation. This is because hybrid poplars need intensive weed management (mechanical and herbicide) for the trees to survive and prosper. The native populations of weed, shrub, and tree species will likely suppress any annual crop of small seedlings.

The NRRI Hybrid Poplar Program has established over 45 field sites throughout Minnesota and the Midwestern and Northeastern U.S., and has never witnessed escaped seedlings surviving outside the plantings. It should be noted also that hybrid poplars have been planted across the U.S. landscape as windbreaks and landscape trees for over 50 years with no documented invasive species concerns.

Link to YouTube video: Are Hybrid Poplar Invasive?

How do Hybrid Poplar Plantations affect native birds and mammals?

Several research studies have been done to assess the effects of hybrid poplar plantations on native birds and mammals. It is helpful to keep in mind that hybrid poplar plantations are planted as an agricultural crop on marginal agricultural land. Therefore the effects of hybrid poplar plantations on native birds and mammals should be compared to the effects of agricultural cropland. Relevant quotations and references from the studies are listed below.

“We studied abundance and species composition of birds and small mammals on hybrid poplar (Populus spp.) biomass plantations and other nearby land use types in the northcentral United States. There were few differences in mammal abundance or diversity between hybrid poplar plantations and rowcrop or small-grain fields. Avian abundance and species richness were consistently higher on plantations than in rowcrop or small-grain fields. Our findings suggest little negative site-level effect on songbirds or small mammals resulting from replacement of rowcrop or small-grain fields with hybrid poplar;”

Christian, D., Collins, P., Hanowski, J., & Niemi, G. (1997). Bird and small mammal use of short-rotation hybrid popular plantations. Journal of Wildlife Management, 61(1), 171-182.

“Plantations provide habitat at least as favorable for native birds and mammals (as evidenced by overall density, species richness, and species composition) as agricultural croplands.”

Christian, D., Hoffman, W., Hanowski, J., Niemi, G., and Beyea, J. (1998). Bird and mammal diversity on woody biomass plantations in North America. Biomass and Bioenergy, 14(4), 395-402.

“Numbers of breeding bird individuals and species in plantations were lower than in surrounding forest/shrub habitat, but higher than in row crops.”

Hanowski, J., Niemi, G., & Christian, D. (1997). Influence of Within‐Plantation Heterogeneity and Surrounding Landscape Composition on Avian Communities in Hybrid Poplar Plantations. Conservation Biology, 11(4), 936-944.

Link to YouTube video: How do Hybrid Poplar Plantations Affect Native Animals?

Are NRRI’s hybrid poplar trees GMO (genetically-modified organisms)?

NRRI’s hybrid poplar program does not use genetically-modified organisms. The program uses conventional applied breeding techniques of parent identification and mating plans by means of controlled pollinations in an isolation greenhouse. This is how most plants are bred.

Extracted pollens (forced from the male parents) are applied directly to the female florals in controlled combinations in the greenhouse. Pollens can be brushed on by hand (camel hair brushes) or using an artificial pollination (air blown) technique. NRRI’s hybrid poplar trees are not GMO.

Link to YouTube video: Are NRRI Hybrid Poplars Genetically Modified?

Can hybrid poplar trees be used for phytoremediation?

Hybrid poplar trees are standing by to help us clean up environmental messes. Phytoremediation is the use of plants to clean contaminated soil, sediment, and groundwater.

This video explores a partnership between the Natural Resources Research Institute at UMD and Ron Zalesny, USDA Forest Service, to use hybrid poplar trees for phytoremediation research.

Link to YouTube video: Using Hybrid Poplar for Phytoremediation

Is there a need for Short-Rotation Woody Crops, like hybrid poplar, with excess forest residues, and an abundance of underutilized, diseased and damaged species?

There is a place for both SRWC (Short-Rotation Woody Crops) and forest residues in the emerging bioeconomy of the Midwest. SRWC plantations are purpose-grown and dedicated biomass/woody feedstocks for end-use markets. The SRWC fibers are high-quality and the supply and costs are controlled by an overall marketing and management plan. Successful plantations are predictable for timing, quality, and quantity going to a dedicated end use or processor.

SRWC are easier to convert into bioenergy and bioproducts than other hardwood or softwood species. Conversion facilities prefer a consistent feedstock, especially for biochemical processes. Dedicated SRWC plantations deliver the consistent feedstock that conversion facilities prefer.

The supply of available mill residues is affected by cycles of sawmills or fiber processing. Underutilized or damaged wood supplies introduce difficult to use, or contaminated fiber supply. Forest residues (logging slash) are a low quality feedstock due to dirt contamination and high bark content--characteristics deleterious to many manufacturing processes.

Lastly, dedicated energy crops are necessary to meet U.S. goals for feedstock supply for a bioenergy industry. This comes from the 2011 U.S Billion-Ton Update: Biomass Supply for a Bioenergy and Bioproducts Industry. The analysis was made to determine if conterminous U.S. agriculture and forestry resources had the capability to produce at least one billion dry tons of sustainable biomass annually to displace 30% or more of the nation’s present petroleum consumption.

The table below, from the updated 2016 U.S. Billion-Ton Report, shows the need for dedicated energy crops to supplement forestry resources and agricultural waste.