Biofuel feedstocks: the risk of future invasions

Nov 2007

In an effort to decrease greenhouse gas emissions, expand domestic energy production, and maintain economic growth, public and private investments are being used to pursue dedicated feedstock crops for biofuel production. Unlike food crops grown for grain-based ethanol (e.g. corn), which require high inputs of fertilizers and pesticides and typically are grown on prime agricultural land, proposed lignocellulose-based energy crops (e.g. switchgrass) typically have a neutral or negative carbon budget, require relatively few economic or environmental inputs, and can be cultivated on marginal, lower-productivity land. Thus, a rapidly growing industry related to crop selection, cultivar improvement, and conversion technologies is emerging.
A variety of plant species, including grasses, herbs, and trees, are being considered for use as dedicated biofuel crops across much of the United States. The leading candidates for lignocellulose-based energy, however, are primarily rhizomatous (i.e. having belowground vegetative reproductive structures) perennial grasses. Most of these grasses are not native to much of the region where production is proposed. From an agronomic perspective, their life history characteristics, rapid growth rates, and tonnage of biomass produced by these non-native grasses make them ideal feedstock crops.
Unfortunately, several of the candidate biofuel feedstock species being considered for commercial production in the United States are invasive pests (i.e. non-native species causing economic or environmental damage) in other regions where they have been introduced. Their invasiveness is attributed mainly to their life history characteristics and rapid growth rates. The combination of being non-native and possessing weedy characteristics, along with their potential scale of cultivation, presents a significant risk that biofuel crops could escape cultivation and potentially damage surrounding ecosystems. Biofuel crops likely will be cultivated on lands surrounded by sensitive forest, prairie, desert, and riparian areas, as well as by rangelands and agricultural commodities.

By: J. M. DiTomaso, J. N. Barney, A. M. Fox

 
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