Extra Credit 1: Science Symposium Insects, Trees and Climate by Roger Call

Science Symposium: Insects, Trees and Climate: The Bioacoustic Ecology of Deforestation and Entomogenic Climate Change

James Crutchfield, from the UC Davis Department of Physics and the Complexity Science Center, presented on the bioacoustic ecology of deforestation and the entomogenic climate change.  This lecture centered around a certain bark beetle which is currently destroying millions of acres of forest throughout North America.  Crutchfield did not speak on the origins or emergence of these beetles, but focused on their effects and propagation as well as the effects they are having on the environment and ecology.

The story of the bark beetles was presented in a fashion most suited to the Desma9 class, in that it was both a story of art and science.  Sound plays a central role in this account.  Crutchfield had originally visited a friend in Michigan who had a graduate student working on a project involving Tanzanian frogs.  These frogs were the last of their species as the Tanzanian government had dammed the river that was their native homeland.  The graduate student was trying without success to make the frogs breed, as this was critical to their survival as a species.  The natural habitat of the frogs involved a waterfall, and through some theorizing and the use of expensive ultrasound equipment, the group discovered that the frogs emitted high frequency sounds as a part of their mating ritual, and with the addition of a waterfall, the frogs began to mate successfully.

This leads into the second part of the lecture, which deals with the beetles and ultrasound.  Recent studies by Crutchfield and others in the field have lead to the discovery that pine trees during a drought release a very high frequency sound.  This sound originates from the imploding cells in the tree due to lack of water.  This sound was a mystery to scientists until just recently.  The high frequency sound let off by the parched trees in turn attracts the bark beetles, which have infested the forests of North America in the past years.

The bark beetle infestation is currently unchecked, as millions of acres of forest are being ravaged despite counter measures.  In Norway, another area affected by the bark beetle problem, billions of beetles were killed in an area, but no effect on the overall beetle infestation occurred.  The study on the ultrasound emitted from trees also lead to the investigation of sounds and these bark beetles.  The beetles are a major concern as the destruction of forests hits the economies of many areas, as precious lumber is being devoured and wasted.  Crutchfield and his associated developed a method of bioacoustics in which they hammer a large ultrasound needle into the bark of a tree, and thus are able to listen for the characteristic high pitched frequencies the beetles emit.  Through this method they can determine if the beetles have infested a tree.  This frequency is very high, as the beetles range of hearing ranges from 200-300 kHz.  These beetles are even changing the climate through destruction of the forests, as a destroyed tree released carbon into the environment, and is also not alive to convert CO2 into oxygen.  Through this process the beetles are altering the climate.  As of now there is no solution to the beetles, but measures to fight them utilizing sound are in progress.

Roger Call

Section C

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