Weeds by any other name

Rob Colautti, a postdoctoral scholar at Duke University, contacted me to alert me to a fascinating international “citizen science” project that is currently underway investigating invasive plant species. Colautti co-founded the project in 2009 and says the response has been beyond expectations. “After our first field season we have more data on abundance, size and distribution of invasive species than any published study to date,” he told me, “We are hoping to raise awareness to increase participation even further this summer.”

For decades, invasive species have been invading many of North America’s managed resources and natural ecosystems, with few effective control options, Colautti says. Hunters, farmers, and environmentalists have tried to work together to stop the spread of invasive species, but now scientists, educators and citizens are using the Global Garlic Mustard Field Survey to look for more effective control options.

Invasive species are plants, animals and microbes that were introduced by humans and now grow out of control, often with negative effects on the integrity of natural resources. The zebra mussel, snakehead fish, fire ants, kudzu, knapweed, thistles and garlic mustard are just a few well-known examples of highly invasive species.

Colautti and colleagues Steve Franks, and Oliver Bossdorf are now recruiting an army of citizen-scientists to help with their research this summer.

“The problem with invasive species is that they invade over large distances,” explains Colautti, “Individuals from different areas of the continent can be quite distinctive in a number of ways. This can affect how invasive they become, but it is hard to conduct research on such a large geographical scale.” A comprehensive sampling effort is needed but without the expense and labor.

Colautti and Bossdorf designed a research program based on the principle of ‘crowd-sourcing’ – outsourcing the bulk of the data collection to individuals across North America. Their reasoning was that individual citizens without formal science training had a numerical advantage over professional scientists. So a large crowd of people might succeed where highly trained scientists could not. Participation requires little more than a measuring stick, tape measure, several large envelopes, and a few hours to carry out the instructions. A GPS device is helpful but optional.

Garlic Mustard invades North American forests and can prevent the growth of new trees, including economically valuable hardwoods like Oak. It does so by disrupting soil microbes that are important for a number of native species. That’s why Bossdorf and Colautti chose Garlic Mustard for their pilot project, and they are planning to expand to include other invasive species.

The garlic mustard survey sampled sixty-five locations over three months last summer, but Colautti and his colleagues estimate that they need at least four or five times as many locations – ideally hundreds of locations across North America and Europe – to get an accurate picture of the Garlic Mustard invasion.

“We don’t even have data to tell us if invasive species like Garlic Mustard are any different in North America than in their native range in Europe,” says Franks.

Despite the potential to wreak havoc on natural ecosystems and related economic activities, invasive species are actually the exception rather than the rule. Only a few of the thousands of species introduced by humans become invasive pests, and only in some locations, but scientists still do not understand why.

Invasive species affect a wide range of industries, from sewage treatment plants to recreational fishing to forestry and agriculture. They can be important vectors for human diseases like Malaria or the West Nile virus. These effects often result in significant ecological and economic harm – $120 billion per year or more according to one study.