Guam experiences more tropical cyclones than any other state or territory in the United States. These cyclones--called typhoons in the western Pacific Ocean--can be devastating to Guam's dense native forests.
The 300+ species of cycads comprise the most threatened group of plants studied to date. Guam's Cycas micronesica is being endangered by recent alien insect invasions.
Credit: Photo by Thomas Marler
The impact of large-scale tropical cyclones affects the health of managed and unmanaged forests, urban landscapes, and perennial horticulture plantings for many years after the actual storm. In fact, the island's forests are often called 'typhoon forests' because their health and appearance is inextricably defined by the most recent typhoons.
As recently as 2002, Cycas micronesica was the most abundant tree species in Guam. The species is recognized for its innate ability to recover from damage after a tropical cyclone. Resprouting on snapped tree trunks, or "direct regeneration", enabled C. micronesica to sustain its status as the most abundant tree in Guam through 2002. Although native tree species like C. micronesica possess traits that enable them to recover from tropical cyclone damage, invasive pests and other environmental challenges are compromising the species' resiliency.
Thomas Marler from the College of Natural and Applied Sciences at the University of Guam, and John Lawrence from the U.S. Department of Agriculture, Natural Resources Conservation Service reported on a large-scale study of Cycas micronesica in HortScience. The team compared the impact of two tropical cyclones--Typhoon Chaba in 2004, and Typhoon Paka in 1997--on the resilience and health of Cycas micronesica. They noticed that the proportion of trees exhibiting "mechanical failure" during Typhoon Chaba--in which peak wind speeds were less than half of those in Typhoon Paka--surpassed the damage documented during the more powerful Typhoon Paka. "We set out to determine how a tropical cyclone with moderate wind speeds could impose greater mechanical damage to a highly resistant tree species than a more powerful event only 7 years earlier," explained Marler.
Marler and Lawrence discovered that although Typhoon Paka compromised the ability of the C. micronesica canopy to avoid wind drag, it was alien invasions following Typhoon Paka that virtually eliminated C. micronesica's resilience to tropical cyclone damage. The data showed that stem decay caused by earlier damage from a native stem borer reduced the species' tolerance to external forces, resulting in stem failure in Typhoon Chaba. Invasions of two invasive insects (Aulacaspis yasumatsui in 2003 and Chilades pandava in 2005) were found to be responsible for the 100% mortality of the intact portions of the trees' snapped stems during the 5 years after Typhoon Chaba.
"A span of less than one decade allowed two alien invasions to eliminate the incipient resilience of a native tree species to tropical cyclone damage," the authors wrote. "This study underscores the fact that many years of observations after tropical cyclones are required to accurately determine [trees'] resilience."
The complete study and abstract are available on the ASHS HortScience electronic journal web site: http://hortsci.ashspublications.org/content/48/10/1224.full
Founded in 1903, the American Society for Horticultural Science (ASHS) is the largest organization dedicated to advancing all facets of horticultural research, education, and application.
Mike W. Neff | EurekAlert!
Blacklists Protect the Rainforest
24.09.2015 | Rheinische Friedrich-Wilhelms-Universität Bonn
Small Alga – Great Effect
22.09.2015 | Leibniz-Zentrum für Marine Tropenökologie (ZMT)
Self-driving cars will be on our streets in the foreseeable future. In Graz, research is currently dedicated to an innovative driver assistance system that takes over control if there is a danger of collision. It was nature that inspired Dr Manfred Hartbauer from the Institute of Zoology at the University of Graz: in dangerous traffic situations, migratory locusts react around ten times faster than humans. Working together with an interdisciplinary team, Hartbauer is investigating an affordable collision detector that is equipped with artificial locust eyes and can recognise potential crashes in time, during both day and night.
Inspired by insects
An interdisciplinary team of researchers has built the first prototype of a miniature particle accelerator that uses terahertz radiation instead of radio...
At present, tiny magnetic whirls – so called skyrmions – are discussed as promising candidates for bits in future robust and compact data storage devices. At...
In cooperation with the Center for Nano-Optics of Georgia State University in Atlanta (USA), scientists of the Laboratory for Attosecond Physics of the Max Planck Institute of Quantum Optics and the Ludwig-Maximilians-Universität have made simulations of the processes that happen when a layer of carbon atoms is irradiated with strong laser light.
Electrons hit by strong laser pulses change their location on ultrashort timescales, i.e. within a couple of attoseconds (1 as = 10 to the minus 18 sec). In...
At the exhibition BATTERY + STORAGE as part of WORLD OF ENERGY SOLUTIONS 2015 in Stuttgart, the Fraunhofer Institutes for Laser Technology ILT and for Ceramic Technologies and Systems IKTS will be showing how laser technology can be used to manufacture batteries both cost- and energy-efficiently.
In the truest sense, it’s all about watts at the Dresden-based Fraunhofer Institute for Ceramic Technologies and Systems IKTS and the Aachen-based Fraunhofer...
01.10.2015 | Event News
30.09.2015 | Event News
17.09.2015 | Event News
07.10.2015 | Life Sciences
07.10.2015 | Machine Engineering
06.10.2015 | Information Technology