Displaying items by tag: ornl science news
Tree “flagging” is a lingering sign of the 17-year cicadas’ brief time on Earth
(Alexandra DeMarco is an intern in ORNL’s media relations group.)
On the road leading to the U.S. Department of Energy’s Oak Ridge National Laboratory, drivers may notice that many of the green trees lining the entrance to the lab are dappled with brown leaves. At first glance, the sight isn’t extraordinary, as deciduous tree leaves turn hues of oranges and browns before falling to the ground each autumn.
Yet, just weeks past the summer solstice, this phenomenon is out of place and is in fact evidence of another natural occurrence: cicada “flagging.”
This spring, Brood X cicadas emerged from the ground after 17 years and swarmed across the eastern United States, leaving a trail of exoskeletons and echoes of mating calls. Cicadas emerge in such large quantities to withstand predation and successfully maintain their populations, and trees actually play a key role in their life cycle.
A male cicada attracts a female through a mating call, the sound responsible for cicadas’ shrill hum. After the two mate, the female cicada uses a sharp tubular organ called an ovipositor to slit the bark and split the sapwood of young tree branches to deposit her eggs there. These incisions, however, damage a tree’s vascular system and can cause stalks beyond the incision to die and wither, leaving behind twigs with brown leaves that resemble flags dangling from the trees.
The eggs then grow into nymphs that make their way to below ground. An oft-repeated misconception is that they’ll stay dormant for 17 years. Actually, during that time, they go through 5 life stages while feeding on the xylem (tree sap) of roots. This may further weaken saplings that were heavily infested with cicadas.
Scientists link research to students’ lives and communities
(Editor's note: Karen Dunlap is a public information officer at Oak Ridge National Laboratory).
Esther Parish is one of eight Oak Ridge National Laboratory scientists talking to students in nine schools across East Tennessee as part of National Environmental Education Week.
On Monday, she spoke to Cathy Kimball’s fifth-grade class at Lenoir City Middle School.
The discussion covered renewable energy resources, science career paths and how climate change may affect East Tennessee.
Other ORNL scientists, including Debjani Singh, Liz Agee, Shelaine Curd, Spencer Washburn, Colleen Iversen, Keith Kline and Matthew Langholtz are participating in classroom events through April 30.
The national event is organized by the National Environmental Education Foundation (NEEF), which celebrates environmental education.
“I think it is important to reach out to young people about environmental science because the choices that our society makes regarding renewable energy resource development and climate-change mitigation will have long-term effects on their environment, health and future quality of life,” Parish said. She is a member of ORNL’s Environmental Science Division and specializes in geography and landscape ecology.