In the United States, only species listed on state or federal noxious weed lists are regulated. According to our analysis, these regulatory lists poorly represent invasive plants in unmanaged (i.e., nonagricultural) systems. To improve the representation of invasive plants on state regulatory lists, we recommend allocating listing authority to invasive species councils and provide guidance for the science-based reform of noxious weed lists. We also recommend commercial best practices to test for invasiveness prior to intentional introduction of new plant products. Finally, we introduce a negligence liability scheme to discourage the introduction of potential invaders. If adopted, our recommendations could benefit nonagricultural ecosystems and could have positive consequences for bioenergy producers and others in plant industry, who are under scrutiny for promoting potentially invasive species as energy crops. As the bioenergy industry gains momentum, a revised regulatory regime may alleviate the concerns regarding one potential negative consequence of novel plant introduction.

In 2009, the European Union (EU) Renewable Energy Directive (RED) mandated that 20% of the EU's fi nal energy consumption consist of renewable sources by 2020, and included sustainability criteria for liquid biofuels. Discussions around extending criteria to solid and gaseous biomass, including wood pellets, have been ongoing. Continued investment in forest bioenergy feedstock production is partly dependent on the stability of global market demand and the economic viability of feedstock production and trade. For trans-boundary governance mechanisms such as the RED to be effi cient, a proper assessment of the specifi c forest and land policy contexts of wood pellet exporters that the mechanism will affect, such as Canada, the USA, and Russia, is crucial. This paper builds on sustainability criteria for biodiversity protection and assurance of sustainable forest management (SFM) for woody biomass that are currently under discussion for inclusion in the RED and compares them with national and local regulations of those three countries. This illustrates potential challenges in the establishment of sustainability criteria related to: differences in land defi nitions, delineation and reporting systems; lack of a uniform defi nitional paradigm for SFM; and diffi culties in establishing effi cient monitoring/auditing systems. Regulators wanting to implement supra-national sustainability schemes such as the EU RED need to be aware of challenges that such schemes carry and make efforts to reduce or eliminate pitfalls. There is also a need to assess the aggregated effects of these various tools, and a need for communication, collaboration and outreach among stakeholders.

Concerns about invasions by novel bioenergy feedstocks are valid, given the parallels between the traits of energy crops and those of many common invasive plants. As the bioenergy industry is poised to introduce nonnative bioenergy crops to large acreages in the United States under state and federal mandates, it is important to consider these concerns -and not simply in an academic sense. Instead, the prevention of invasions should be codified in statutes and regulations pertaining to bioenergy production on both the state and federal level. Unfortunately, this is not occurring regularly or consistently at this time. The few existing regulations that do consider invasiveness in bioenergy systems suffer from vague terminology that could have major economic, environmental, and legal consequences. Here, we discuss existing regulatory challenges and provide solutions to address invasion potential of bioenergy crops. We provide model definitions and provisions to be included in revised or new state and federal regulations, including an invasion risk assessment process, a permit and bond system for high-risk crops, and a risk mitigation provision for all novel crops. Our proposal provides a consistent and transparent system that will allow the industry to move forward with minimal risk of invasion by novel feedstocks.

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