Researchers use non-invasive sonic technology to measure wood decay in living, tropical trees
Living trees can rot from the inside out, leaving only a hollowed trunk. Wood rot in living trees can cause overestimates of global carbon pools, timber loss in forestry, and poor tree health. Understanding wood decay in forests is of special concern in the tropics because tropical forests are estimated to harbor 96% of the world's tree diversity and about 25% of terrestrial carbon, compared to the roughly 10% of carbon held in temperate forests.
Tomogram showing areas of wood decay in a tree with an irregularly shaped trunk, based on sonic tomography with the PiCUS 3 Sonic Tomograph.
Javier O. Ballesteros and Gregory S. Gilbert. From Gilbert, Gregory S., Javier O. Ballesteros, Cesar A. Barrios-Rodriguez, Ernesto F. Bonadies, Marjorie L. Cedeño-Sánchez, Nohely J. Fossatti-Caballero, Mariam M. Trejos-Rodríguez, et al. 2016. Use of sonic tomography to detect and quantify wood decay in living trees. Applications in Plant Sciences 4(12): 1600060. doi:10.3732/apps.1600060.
But how do foresters and researchers see into a living tree to measure wood decay? They use sound.
In a recently published article in Applications in Plant Sciences, a team of professors, teachers, and students established methods for using a sound wave technology called sonic tomography. Their methods were derived from measurements on more than 1,800 living trees of 173 tropical rainforest tree species in the Republic of Panama.
"We don't yet know where internal decay and damage rank as a cause of tree mortality," says Greg Gilbert, lead author of the article and Professor and Chair of the Department of Environmental Studies at the University of California, Santa Cruz. "Most of the decay is hidden--the tomography now allows us to see how many apparently healthy trees are actually decayed inside."
Sonic tomography sends sound waves through tree trunks. The longer it takes for a sound wave to traverse a trunk, the more decayed the wood. Based on the velocity of sound, the tomograph (PiCUS 3 Sonic Tomograph; Argus Electronic GmbH, Rostock, Germany) makes a color-coded image of a cross section of the trunk (see Figure).
Previous use of sonic tomography in forestry has focused on measurements in "typically shaped" trees with cylindrical trunks. However, tropical trees often have large buttresses, irregular trunk shapes, and prop roots that extend up the tree. The new study describes optimum placement of the sensors to avoid aberrant tomography results for the non-model tree shapes that populate the tropics and details how to analyze the tomograms to quantify areas of decayed and damaged wood.
The sonic tomography methods were developed and tested during an international field course for high school, college, and graduate students in the Republic of Panama and funded through the National Science Foundation. Gilbert and colleagues took students and their teachers into the field and used inquiry-based learning to teach molecular and field approaches to ecology, as well as foster an international pipeline to ecological research. Gilbert comments, "It was an exciting dive, with amazing people from diverse backgrounds, into the messy part of doing science--figuring out how best to do what you need in order to answer difficult questions." All of the workshop participants contributed to the sonic tomography data collection and analysis for the article.
Fungi cause wood rot by entering a tree trunk and decaying wood from the inside out, releasing carbon back into the atmosphere as carbon dioxide. Gilbert explains that without a reliable method to detect missing wood, you cannot understand how trees are contributing to or moderating increasing levels of global atmospheric carbon, or how apparently healthy forests and tree species are responding to shifts in climate.
Gilbert's research on wood decay is building toward a large study about how pathogens and diseases control the prevalence of tropical tree species. "The hypothesis is that species that are more susceptible to heart rot fungi will usually remain rare in the forest, and only those species that are resistant will become common," says Gilbert. He and his colleagues are measuring and tracking tropical trees in the Smithsonian Tropical Research Institute's long-term Forest Global Earth Observatory (ForestGEO) site on Barro Colorado Island in the Panama Canal.
Future work will continue validating sonic tomography technology for tropical tree systems using felled or already dead trees. Tropical trees are highly diverse in both form and function, and they are thus potentially distinct in their methodological requirements for sonic tomography. For example, this method does not work on palm species or any tree species that use internal tissues to store water.
Urban forestry also benefits from sonic tomography. Gilbert and colleagues with the Smithsonian Tropical Research Institute are collaborating with Panama City to use tomography to evaluate the health and property risks of Panama's urban trees that may be decayed and vulnerable to snapping in high winds and heavy precipitation.
Gilbert, Gregory S., Javier O. Ballesteros, Cesar A. Barrios-Rodriguez, Ernesto F. Bonadies, Marjorie L. Cedeño-Sánchez, Nohely J. Fossatti-Caballero, Mariam M. Trejos-Rodríguez, et al. 2016. Use of sonic tomography to detect and quantify wood decay in living trees. Applications in Plant Sciences 4(12): 1600060. doi:10.3732/apps.1600060
Applications in Plant Sciences (APPS) is a monthly, peer-reviewed, open access journal focusing on new tools, technologies, and protocols in all areas of the plant sciences. It is published by the Botanical Society of America, a nonprofit membership society with a mission to promote botany, the field of basic science dealing with the study and inquiry into the form, function, development, diversity, reproduction, evolution, and uses of plants and their interactions within the biosphere. APPS is available as part of BioOne's Open Access collection.
For further information, please contact the APPS staff at email@example.com.
Beth Parada | EurekAlert!
How molecules teeter in a laser field
18.01.2019 | Forschungsverbund Berlin
Discovery of enhanced bone growth could lead to new treatments for osteoporosis
18.01.2019 | University of California - Los Angeles
The scientific and political community alike stress the importance of German Antarctic research
Joint Press Release from the BMBF and AWI
The Antarctic is a frigid continent south of the Antarctic Circle, where researchers are the only inhabitants. Despite the hostile conditions, here the Alfred...
World first experiments on sensor that may revolutionise everything from medical devices to unmanned vehicles
The new sensor - capable of detecting vibrations of living cells - may revolutionise everything from medical devices to unmanned vehicles.
Dead and alive at the same time? Researchers at the Max Planck Institute of Quantum Optics have implemented Erwin Schrödinger’s paradoxical gedanken experiment employing an entangled atom-light state.
In 1935 Erwin Schrödinger formulated a thought experiment designed to capture the paradoxical nature of quantum physics. The crucial element of this gedanken...
Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.
It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:
The phenomenon of so-called superlubricity is known, but so far the explanation at the atomic level has been missing: for example, how does extremely low friction occur in bearings? Researchers from the Fraunhofer Institutes IWM and IWS jointly deciphered a universal mechanism of superlubricity for certain diamond-like carbon layers in combination with organic lubricants. Based on this knowledge, it is now possible to formulate design rules for supra lubricating layer-lubricant combinations. The results are presented in an article in Nature Communications, volume 10.
One of the most important prerequisites for sustainable and environmentally friendly mobility is minimizing friction. Research and industry have been dedicated...
16.01.2019 | Event News
14.01.2019 | Event News
12.12.2018 | Event News
18.01.2019 | Materials Sciences
18.01.2019 | Life Sciences
18.01.2019 | Health and Medicine