Invasive Bioenergy Crops Could Threaten Plant Biodiversity.

Yet another cautionary example that biofuel production is far from being environmentally benign. Amidst the back and forth commentary, for and against their usage, a biofuel crop case study out of Hawaii suggests many introduced plants pose a serious threat to native biodiversity.

New news? Not really, but when placed in the context of the EU's renewable energy goals (pdf)--which include increasing the share of renewables in energy use to 20 per cent by 2020, and a minimum 10 per cent share for renewable energy in transport by 2020--the question of how this is being addressed continually arises.

You may be thinking, Hawaii isn't in the EU. Quite right. The Hawaiian study just so happens to carry universal application for all tropical and subtropical ecosystems. And those exist around the globe.

What's the Problem?

The renewability of biofuels has always been met with a modicum of controversy. From water consumption to Nitrogen Oxide emissions to antibiotic residuals found in crops, and let's not forget the precarious balance of land for crops vs. land for bioenergy, this supposedly green industry requires a lot of refinement. The concern for ecosystem biodiversity is just as relevant.

The study, based out of the University of Hawaii at Manoa, adapted an established tool called the Weed Risk Assessment (WRA) for use in native and Pacific regions. The WRA mitigates the impacts of intentional plant introductions. The research compared the risks of invasion of a list of 40 bioenergy crops that have been proposed for Hawaii to a random sample of 40 non-bioenergy plants that have already been introduced.

The results aren't pretty. Bioenergy crops were 2 to 4 times more likely to be invasive or establish wild populations. Using the adapted WRA's threshold for high risk, the research identified 70 per cent of bioenergy species as high risk compared to a quarter of a random selection of introduced non-bioenergy species.

Remember the kudzu vine? Initially purchased from the Japanese by the US in 1876 as a means to control soil erosion, by 1953 it was labeled a pest weed due to its rapid growth (see photo inset)--especially in the southeastern regions. Kudzu has naturalized into about 20,000 to 30,000 square kilometers (7,700–12,000 sq mi) of land in the United States and costs around $500 million annually in lost cropland and control costs.

The same concerns are associated with other introduced plant species, especially those about to be grown en masse for bioenergy production. With optimum variables (sun, shade, temperate climes, proper water), hearty plants like Jatropha and the aforementioned kudzu can run rampant.

Solutions?

Well, it's important first of all to note that not all biofuel crops are invasive. Algae in particular comes to mind, as it uses up very little space and has minimal environmental impact. The trouble with Algae is that it still requires a fair amount of finessing before it can be used in vast quantities. But in my mind it carries the most potential.

Selective planting is also a must. While jatropha or gorse may be viable in some areas, the potential for them to take over large amounts of land is great in others. Christopher Evan Buddenhagen, head author of the study, suggests Governments should give priority to non-invasive or less invasive species before granting funds or approval for biofuel planting programmes.

The study even went so far as to imply the method of "the polluter pays" should be applied to the negligent introduction of invasive crops.

"Planting of potentially invasive species near important natural areas with high biodiversity should be discouraged," Buddenhagen said. "If a crop species has a high risk of being invasive, the likelihood of it becoming invasive is worsened by planting it on a large scale." 

Extensive planting - expected under large-scale bioenergy crop cultivation - will encourage invasions. There is further cause for concern if the invasions are near vulnerable natural areas with high-value biodiversity.