Wi-Fi may not be a tree killer after all.
Or it might be.
In any case, recent headlines about a connection between Wi-Fi signals and an increase in tree sickness were apparently not the place to look for an answer.
According to a story in The Wall Street Journal, Dutch researchers have called into question data that prompted the widespread reports that Wi-Fi signals were to blame for a jump in poor-health indicators among urban trees in the Netherlands and perhaps elsewhere.
The people behind an investigation in the Dutch city of Alphen aan den Rijn say that numbers involved in the study were improperly characterized and that an experiment conducted as part of the inquest did not include adequate controls.
"We cannot draw conclusions" based on the findings, Andre van Lammeren, who conducted the experimental aspect of the inquest, told the Journal.
Van Lammeren, an associate professor of plant cell biology at Wageningen University, was called in after a city official in Alphen aan den Rijn noticed stress-indicating bumps on the bark of many of the city's trees.
In 2007, a survey found that 11 percent of the trees had the bumps, the Journal reported. This year, the figure had risen to 30 percent--and 70 percent of the trees bore some sort of irregularity, including, but not limited to, the bumps. Some media outlets reported that signs of damage had jumped from 10 percent to 70 percent in the course of a few years, when in fact there was no earlier number for the mix of irregularities covered by the 70 percent figure.
The media also reported on the experiment van Lammeren devised as a way of testing the city official's theory that Wi-Fi signals might be the cause of the irregularities.
Van Lammeren placed a number of small trees in a cabinet along with several Wi-Fi hotspots. He also placed trees in a box without hotspots. After three months, the Wi-Fi exposed trees showed leaf damage (though the damage was never precisely measured).
Van Lammeren told the Journal that the experiment was "preliminary," that each tree should have been placed in its own cabinet as a more strict control, that the leaf damage that was discovered might not have been all that serious, and that it was difficult to apply the findings to the trees' normal outdoor environment. He also said he regrets the study was publicized and that at the time his university had issued a statement cautioning against sweeping conclusions. The Journal also suggested that poor computer-aided translations of Dutch media reports added to the confusion.
It's not the first time Wi-Fi has been pegged as the culprit in a crime against nature. Some have speculated that Wi-Fi signals, cell phone transmissions, and the like may be the cause of a spike in honey bee deaths. Evidence, however, remains inconclusive, with some saying the deaths are the result of a combination of factors, and some contending that the villain is a lethal mix of a fungus and a virus.
The Journal quoted an arborist with the U.S. Forest Service as saying that other problems facing urban trees, such as soil compaction, would have to be screened out in order to determine the true effect of Wi-Fi.
Other researchers have found connections between Wi-Fi signals and poor health in trees, but not all those studies have been peer-reviewed, the Journal said, adding that the city of Alphen aan den Rijn plans to host some of these researchers at a symposium on the topic early next year.