Use of Invasive Species

Invasive species are an emerging and expanding problem that has resulted in a tremendous increase in social and economic costs, as well as ecological stresses to native species and natural communities.  Desirable traits for bioenergy crops, such as high productivity, low input requirements and wide habitat breadth, are also traits of invasive species.  Hence, the expansion of biomass plantings and harvesting represents a potential increased risk of invasive species on the landscape.

A risk of all agricultural endeavors is possible escape of introduced novel crops (biomass or otherwise) into landscapes where they could potentially become invasive.  Such is the case with Miscanthus, a warm-season grass with high potential for biomass feedstock utilization because of its high productivity (figure 4.6).  Miscanthus x giganteus, the variety most likely used in bioenergy production, is a sterile cross of two known invasive Miscanthus parents.  That is, the seed of Miscanthus x giganteus is sterile, and the plant must propagate vegetatively.  However, visual differentiation of the sterile Miscanthus x giganteus from its invasive parents is especially difficult and certified sterility of tubers is lacking.  Moreover, seed sterility does not guarantee lack of invasion.  Vegetative propagation is often associated with invasiveness.

While risk of invasion of novel species and crops is a possibility associated with bioenergy, so is expansion of current invaders that have bioenergy feedstock potential.  Reed canary grass (Phalaris arundinacea) is a drought-tolerant tall perennial grass of wetlands and moist areas that has become a noxious invasive across much of the U.S. Midwest.  It is under consideration for use as feedstock, particularly for combustion in biopower facilities.

While there is a native ecotype, Eurasian varieties were brought to the U.S. as a forage and hay crop.  The more aggressive introduced Eurasian varieties have escaped areas where they are being purposefully cultivated into surrounding areas, causing ecological harm.  In highly disturbed areas with little probability of restoration, however, harvest of reed canary grass has a potential benefit not only as biopower feedstock but for removing excess nutrients from agricultural run-off (see Jakubowski et al., 2010).