The traits that make a good bioenergy crop — high productivity in a range of environments with low need for fertilizer or water, vulnerable to few pests, and rapid regrowth — are similar to the characteristics that can make a species very invasive. So, without some careful attention to smart policy, the explosion of interest in growing biofuels has the potential to introduce many species to the United States that could turn out to be expensive to control.
Rather than banning, or “blacklisting” known invasive species and making everything else fair game, a group of researchers have taken the initiative to put together a “white list” of species with low potential to become invasive. If growers could limit themselves to these species – voluntarily or through regulatory or incentivized fast tracks — it might be possible to grow biofuels without displacing food crops or introducing expensive new weeds.
Confidence for Growers; Caution for Conservationists
The approach — published this week in the journal Bioenergy Research by scientists from the University of Illinois, The Nature Conservancy, the University of Florida and the National Wildlife Federation — has benefits for both growers and conservationists. A white list would allow both the regulatory community and the biofuel industry to move forward with greater confidence that they are not likely to create the next ecologically and economically harmful invader.
For conservationists, a well-researched list of low invasion risk species greatly reduces the chance of introduced species getting out of hand. After all, over 90% of all ecologically and economically damaging invasive plant species are thought to have been introduced intentionally.
“We’re in favor of bioenergy as one of the sources of non-petroleum based energy,” says Doria Gordon, the Conservancy’s director of conservation in Florida, “but we don’t want to make an error that will require a lot of petroleum-based products to control later.”
The researchers applied the Australian Weed Risk Assessment (WRA) to each of the species on a list of potential biofuel crops gathered from the US Department of Agriculture (USDA), US Department of Energy (DOE) and industry sources. In previous research, the WRA has been consistently accurate in predicting invasiveness – especially for the most and least invasive species, says Gordon.
The outcomes were simple categories: high risk, low risk and needs further evaluation. Species that were clearly low risk – either on the first pass or after further screening with other tools — made it onto the white list. Native species grown in their native ranges also made the list. Starting with a list of 120 possible biofuel crops, they ended up with about 25 non-natives and 24 natives that they could recommend with confidence.
Growers can start using the white list now to guide them to lower risk species. And where plants with particularly desirable traits – such as high oil or sugar content – are on the high risk list, plant breeders can use the WRA to identify traits they might want to eliminate.
The list is only a first step, however, toward resolving some of the policy contradictions that are starting to emerge. Under the current system, one part of the government may be spending money to control an invasive plant, while another part offers incentives under the renewable fuel standard for farmers to grow the same species.
If regulators could agree to a white list — whether they use this proposed list or develop their own — it would be easier to align the incentives to produce more plant-based fuels while reducing the risk of introducing harmful invaders that can impact nature and people.
“If we are seeking to incentivize the cultivation of bioenergy crops,” says Gordon, “then we should take care not to incentivize species that we will regret later. We hope that the white list approach provides a tool for proactive selection of low-risk species.”
Opinions expressed on Cool Green Science and in any corresponding comments are the personal opinions of the original authors and do not necessarily reflect the views of The Nature Conservancy.