(Press-News.org) Athens, Ga. – Weedy plants, many introduced to the U.S. for sale through plant nurseries, are responsible for extensive environmental damage and economic costs. Although legislation restricts the introduction of certain species, the procedures used to select species for inclusion on the restricted list are haphazard and out of date.
To meet the need for more systematic weed risk analysis, researchers at the University of Georgia Odum School of Ecology and the University of California, Davis have developed a "cost-sensitive" model to determine when importing a given plant is worth the risk. Their work was published in the May edition of the journal Ecosphere.
Although the problems caused by invasive plants are well known, Odum School postdoctoral associate J.P. Schmidt, the lead scientist on the study, said the U.S. has historically placed very few restrictions on the import of plants.
According to UC Davis economist and study co-author Mike Springborn, "our approach represents a shift from the current practice of scrambling to address invasives only after they are already established. In this paper, we develop tools for making informed decisions ahead of time about which plants have an acceptable level of risk given their anticipated benefits. We now have the combined biological and economic tools to take an informed look before we leap with trade in new species."
The model uses statistical procedures to assess how likely a plant is to become a weed. To do this, it compares the estimated probability with the average costs of a new weed and the expected losses from foregone sales of non-weed species that are presumably safe. Using the model as a screening tool, the researchers say, would provide a net economic benefit of at least $80,000 to $140,000 per species assessed, which could translate into tens of millions of dollars in total.
Had the proposed screening system been in place historically, they calculated—using just low-end estimates of invasive species damages—that one third of the most noxious species could have been excluded. To realize this benefit, only 15 percent of potential introductions would need to be prohibited.
At its core, the model consists of two parts. First, the researchers sought to identify a small number of plant traits that could be used to predict invasiveness.
"Amazingly, we found that just four traits could discriminate pest from non-pest species with an impressive degree of accuracy," Schmidt said. "Namely, pest species tend to have some combination of the following traits: seeds that are in the mid-range of seed sizes, that have higher chromosome counts than their close relatives, that have affinities for both wetland and upland habitats and that have large native ranges."
"Second," said co-author John Drake, an associate professor at the Odum School, "we asked where to draw the proverbial line-in-the-sand—in this case the line between probable pests and probable non-pests—which requires accounting for the value of the ornamental plant trade and the costs associated with weeds. The economically optimal decision rule is the one that settles that line where it exactly balances the costs from invasion with the benefits from trade."
Schmidt explained that the cost of mistakenly keeping out a non-invasive plant was far lower than the cost of mistakenly allowing an invasive plant in.
To make these results equally accessible to scientists, decision-makers and the interested public, the researchers then encapsulated the resulting decision rule in a series of four graphics. Every plant species can be placed somewhere on these diagrams. The location on the diagram indicates the economically optimal policy—either to admit or deny import.
Although these methods were developed to aid decision-making about potential plant pests, the techniques used may be helpful for other problems in environmental management, for instance in prioritizing rare species for conservation.
Results from the analysis inspired a companion study by Schmidt, Drake and Odum School assistant research scientist Patrick Stephens, in the journal Ecological Applications, which contrasts invasive and rare plants of North America.
Using a much larger data set—the roughly 15,000 species native to the U.S. and Canada—this second study developed predictive models to distinguish species classified as pests together with rankings developed by the Nature Conservancy concerning extinction vulnerability.
"In summary, decisions about allowing plants into the U.S. are being made every day," Schmidt said. "Our models could help to better guide those decisions, potentially saving tens of millions to billions of dollars in costs associated with plant invasions."
###
The full text of the Ecosphere article is available at http://www.esajournals.org/doi/pdf/10.1890/ES12-00055.1. The full text of the Ecological Applications study is available at http://www.esajournals.org/doi/abs/10.1890/11-1915.1.
END
CHICAGO --- Today's senior citizens are reporting fewer visual impairment problems than their counterparts from a generation ago, according to a new Northwestern Medicine study. Improved techniques for cataract surgery and a reduction in the prevalence of macular degeneration may be the driving forces behind this change, the researchers said.
"From 1984 until 2010, the decrease in visual impairment in those 65 and older was highly statistically significant," said Angelo P. Tanna, M.D., first author of the study. "There was little change in visual impairments in adults ...
CERN, the European Organization for Nuclear Research headquartered in Geneva, Switzerland, will hold a seminar early in the morning on July 4 to announce the latest results from ATLAS and CMS, two major experiments at the Large Hadron Collider (LHC) that are searching for the Higgs boson. Both experimental teams are working down to the wire to finish analyzing their data, and to determine exactly what can be said about what they've found.
"We do not yet know what will be shown on July 4th," says Ian Hinchliffe, a theoretical physicist in the Physics Division at the U.S. ...
For the first time comparable migration data is available for almost every country of the world. To date, records were incompatible between nations and especially by gender and age, nonexistent. Emilio Zagheni from the Max Planck Institute for Demographic Research (MPIDR) in Rostock, Germany, for the first time provides a rich migration database by compiling the global flow of millions of e-mails.
"Where estimates of demographic flows exist, they are often outdated and largely inconsistent," says MPIDR researcher Emilio Zagheni. Official records are difficult to use for ...
Researchers at the Hollings Marine Laboratory (HML) and four partner organizations have measured for the first time concentrations of 13 perfluoroalkyl compounds (PFCs) in five different endangered species of sea turtles. While PFC toxicology studies have not yet been conducted on turtles, the levels of the compounds seen in all five species approach the amounts known to cause adverse health effects in other animals.
PFCs are man-made compounds that have many uses including stain-resistant coatings, fire-fighting foams and emulsifiers in plastics manufacturing. They have ...
In yet another Olympian feat of measurement, researchers at the National Institute of Standards and Technology (NIST) recently calibrated a tape that will be used to measure out the distance of this summer's Olympic marathon—a distance of 26 miles 385 yards—to 1 part in 1,000.
Measurement is a vital aspect of the Olympic Games. Officials measure the height of jumps, the speed of races, and the mass of weights to determine who wins a medal and who goes home. The marathon is no different. Because of the difficulties in measuring out the distance, the International Association ...
Gold is not necessarily precious—at least not as a coating on atomic force microscope (AFM) probes.
JILA researchers found that removing an AFM probe's gold coating—until now considered helpful—greatly improved force measurements performed in a liquid, the medium favored for biophysical studies such as stretching DNA or unfolding proteins. As described in Nano Letters,* stripping the gold from the diving-board-shaped probe, or cantilever, with a brief chemical bath improved the precision and stability of force measurements about 10-fold. The advance is expected to quickly ...
Civic leaders, arts organizations, donors and government officials can better plan new or expanded arts facilities by first focusing on the arts organizations' missions and assessing demand for the projects, according to a new study from the Cultural Policy Center at the University of Chicago.
The study, "Set in Stone," looks at a major building boom of museums, performing arts centers and theaters in the United States from 1994 to 2008. It is the first scientifically prepared study of its kind and was requested both by cultural leaders and major foundations that had, ...
(Garrison, NY) A potentially powerful strategy for studying the significance of human genetic variants is to recruit people identified by previous genetic research as having particular variants. But that strategy poses ethical challenges to informed consent, as well as potential risks to the people recruited, and it is unlikely that there is a "one-size-fits-all" solution, concludes an article in IRB: Ethics & Human Research.
The advantage of "recruitment by genotype" is that it eliminates the time-consuming, expensive process of screening new populations to find subjects ...
A 100 kilometre-wide crater has been found in Greenland, the result of a massive asteroid or comet impact a billion years before any other known collision on Earth.
The spectacular craters on the Moon formed from impacts with asteroids and comets between 3 and 4 billion years ago. The early Earth, with its far greater gravitational mass, must have experienced even more collisions at this time – but the evidence has been eroded away or covered by younger rocks. The previously oldest known crater on Earth formed 2 billion years ago and the chances of finding an even older ...
Irvine, Calif., June 28, 2012 — An international consortium of Huntington's disease experts, including several from the Sue & Bill Gross Stem Cell Research Center at UC Irvine, has generated a human model of the deadly inherited disorder directly from the skin cells of affected patients.
The re-created neurons, which live in a petri dish, will help researchers better understand what disables and kills brain cells in people with HD and let them gauge the effects of potential drug therapies on cells that are otherwise locked deep in the brain.
UCI scientists were part ...
