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!
Coorong Fish Hedge Their Bets for Survival
27.03.2015 | University of Adelaide
Greener Industry If Environmental Authorities Change Strategy
27.03.2015 | University of Gothenburg
In an experiment at the Department of Energy's SLAC National Accelerator Laboratory, scientists precisely measured the temperature and structure of aluminum as...
The IPH presents a solution at HANNOVER MESSE 2015 to make ship traffic more reliable while decreasing the maintenance costs at the same time. In cooperation with project partners, the research institute from Hannover, Germany, has developed a sensor system which continuously monitors the condition of the marine gearbox, thus preventing breakdowns. Special feature: the monitoring system works wirelessly and energy-autonomously. The required electrical power is generated where it is needed – directly at the sensor.
As well as cars need to be certified regularly (in Germany by the TÜV – Technical Inspection Association), ships need to be inspected – if the powertrain stops...
When an earthquake hits, the faster first responders can get to an impacted area, the more likely infrastructure--and lives--can be saved.
The Atlantic overturning is one of Earth’s most important heat transport systems, pumping warm water northwards and cold water southwards. Also known as the Gulf Stream system, it is responsible for the mild climate in northwestern Europe.
Scientists now found evidence for a slowdown of the overturning – multiple lines of observation suggest that in recent decades, the current system has been...
Because they are regularly subjected to heavy vehicle traffic, emissions, moisture and salt, above- and underground parking garages, as well as bridges, frequently experience large areas of corrosion. Most inspection systems to date have only been capable of inspecting smaller surface areas.
From April 13 to April 17 at the Hannover Messe (hall 2, exhibit booth C16), engineers from the Fraunhofer Institute for Nondestructive Testing IZFP will be...
25.03.2015 | Event News
19.03.2015 | Event News
17.03.2015 | Event News
27.03.2015 | Physics and Astronomy
27.03.2015 | Information Technology
27.03.2015 | Life Sciences