Could new biofuel crops become invasive?


According to a blog I read in the New York Times (NYT) online this could be the case. Following evidence that biofuel crops compete with food crops, defenders of farm grown crops say the eventual goal is to shift away from sources like maize toward plants harvested for their cellulose, which would end the competition between biofuel and food crops. However, as reported in the article, an unintended outcome of using alternative crops is that some like Jatropha and the giant reed tend to be invasive and could out-compete indigenous plants (see here). This would be a major setback for farmers planning to grow alternative biofuel crops.

After investigating the problem further, it seems widely accepted that there is competition when a food crop is also useful as a biofuel crop, as discussed recently by a fellow blogger 'have you noticed an increase in your supermarket bill?’ which showed that an increase in demand for energy supplies from crops to produce ethanol was a contributing factor in the increase in food prices. Studies have shown that using alternative plant species without proper research on the plant biology may indeed add an unexpected problem of introducing invasive species that could cross the border to other fields and take over the area adjacent to where it was introduced. At a recent UN meeting, scientists from the Global Invasive Species Programme warned about the dangers of introducing invasive species (report), which might result in greater financial losses than gains. On the other hand, the biofuels industry argued that the risk of alternative biofuel crops becoming a weed problem is overstated. They argue that although some proposed biofuel crops have potential to become weeds, they are not all plants that turn invasive. “There are very few plants that are weeds", said W. De Greef, secretary general of EuropaBio. “You have to look at the biology of the plant and the environment where you’re introducing it and ask, are there worry points here?” He also added that biofuel farmers would inevitably introduce new crops carefully because they would not want growth they could not control. Although Jatropha was banned in two Australian Provinces as an invasive species, Mr. De Greef argued that Jatropha had little weed potential in most areas and added: “just because a species has caused a problem in one place doesn’t make it a weed everywhere.” (link to report)

I did not find his arguments very convincing until I read an article from the CAB Abstracts database (1), about a species from the Jatropha genus. Jatropha elliptica is a medicinal herb from the Brazilian cerrados used in folk medicine against severe itches, snake bites and syphilis. Seed germination in field is low and this species has been explored in excess recently, leading the natural populations to decrease drastically. Studies were conducted to develop a micro-propagation protocol for the species in Brazil. Would a species which has shown a population decrease owing to over-use seem in danger of becoming invasive? Has Mr. De Greef got a point after all? At a glance it seems so, but we must be careful not to generalise because although J. elliptica is not a species which might become invasive, J. curcas, the species being grown for its biodiesel potential is an invasive species. The same is true for giant reed; the Florida Native Plants Society and a number of scientists opposed a Florida biofuel plantation and plant project using giant reed, which had been greeted with enthusiasm by investors, its energy sold even before it is built.

An article in the CAB Abstracts database (2) reported results from a study using a weed risk assessment that categorised the risk of a species becoming invasive on the basis of its biogeography, history, biology and ecology. Their results for 3 leading biofuel candidates showed switchgrass to have a high invasive potential in California, unless sterility is introduced; giant reed had a high invasive potential in Florida, where large plantations are proposed; and Miscanthus poses little threat of escape in the USA. This last study proposes genotype-specific pre-introduction screening for a target region, which consists of risk analysis, climate matching modelling and ecological studies of fitness responses to various environmental scenarios. This screening procedure would provide reasonable assurance that economically beneficial biofuel crops will pose a minimal risk of damaging native and managed environments.

The EU is funding a project to introduce the giant reed into EU agriculture. According to its proposal, the giant reed is environmentally friendly and, as a high-yielding crop, it is a cost-effective crop poised to become the “champion of biomass crops”. The EU’s target of 10% biofuel use in transportation by 2020 is binding and as such, politicians are anxiously awaiting the commercial perfection of second-generation biofuels from plants such as the giant reed. Maybe claims that the giant reed and Jatropha could become invasive have been exaggerated. Even so, there is no harm in being cautious and make sure proper screening procedures are carried out to ensure when species are introduced to a new area there is no danger of it becoming invasive.

For further reading, our CAB Abstracts database is packed full with information on invasive species.

If you also want to keep informed about the latest developments on biofuels, you should join the CABI Biofuels Information Exchange ( for free access to over 35,000 research records on biofuels from our CAB Abstracts Database, as well as links to pertinent third party biofuels reports and books, news summaries, discussion forum and more!

1 Campos, R. A. S.\Añez, L. M. M.\Dombroski, J. L. D.\Dignart, S. L. (2007). Micropropagation of Jatropha elliptica (Pohl) Mu ll. Arg. Revista Brasileira de Plantas Medicinais 9(3): 30-36.

2 Barney, J. N.; Ditomaso, J. M. (2008). Nonnative species and bioenergy: are we cultivating the next invader? BioScience 58(1): 64-70.

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