Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

U.S. Forest Service Study Finds Hemlock Still Abundant Despite Adelgid Infestation

27.09.2011
An analysis of two decades of data collected by the U.S. Forest Service’s Forest and Inventory Analysis (FIA) program shows that the live volume of hemlocks in the eastern United States is increasing despite infestations of hemlock woolly adelgidthat have decimated local populations.

The information comes from an e-Science Update co-authored by scientists from two U.S. Forest Service research stations, the Northern Research Station (NRS) and the Southern Research Station (SRS), and published by SRS.

“The update provides an overview of the status and extent of hemlocks in the in eastern United States based on FIA inventories conducted by SRS and NRS,” according to Randall Morin, a research forester with the NRS’ FIA program and the primary author. “It also incorporates research by NRS scientists and the results of pest surveys conducted by the Forest Service’s State and Private Forestry Program.”

Two native species of hemlock – eastern and Carolina – grow in eastern North America. Although a minor component in most of the forests of the eastern United States, high densities of eastern hemlock are found in New England and the mountains of the Southeast and Mid-Atlantic. The Carolina hemlock, similar in appearance to the eastern hemlock, is found only on rocky mountain slopes of the Southern Appalachian region.

Researchers conducted the analysis on 20 years of data collected across 433 counties stretching from southern Maine into northern Georgia. They found an overall increase in live-tree hemlock basal area in counties infested with hemlock woolly adelgid as well as those without infestations.

A tiny insect introduced into the United States from East Asia, the hemlock woolly adelgid, feeds at the base of hemlock needles, defoliating and eventually killing trees. “Since the insect was first noticed in the 1950s it has expanded its range at between 4.7 and 12.7 miles a year,” according to Andrew Liebhold, an NRS research entomologist. “Hemlock woolly adelgid currently infests about 45 percent of the range of hemlocks in the United States and 41 percent of the total hemlock basal area.” These percentages are up 26 percent and 25 percent respectively since 2004.

“The analysis also showed that the general regional trend in the East over the past 50 years has been one of increasing hemlock volume, even with infestation by the hemlock woolly adelgid,” according to Sonja Oswalt, an SRS forester and co-author. “Even though the insect has caused substantial negative impacts on hemlock at stand-level scales, analysis of FIA data suggests that infestations have not yet reduced the overall abundance of hemlock, even in states where hemlock woolly adelgid has been active for decades.”

The authors caution that the trend of increasing hemlock volume may not last much longer. “Despite increasing hemlock volume over the last four decades across most of the eastern United States, the regions with long-established populations of hemlock woolly adelgid are also the regions where hemlock is accumulating slowest,” Morin said. “Net growth rates decrease as years of infestation increase, and mortality rates increase, with mortality starting to equal net growth in areas where hemlock woolly adelgid has been present for 10 to 20 years.” As time goes on the trend of increasing abundance may begin to reverse.

The Science Update is available at: http://www.srs.fs.usda.gov/pubs/38492

The mission of the U.S. Forest Service is to sustain the health, diversity, and productivity of the nation’s forests and grasslands to meet the needs of present and future generations. The agency manages 193 million acres of public land, provides assistance to state and private landowners, and maintains the largest forestry research organization in the world. The mission of the Forest Service’s Northern Research Station is to improve people’s lives and help sustain the natural resources in the Northeast and Midwest through leading-edge science and effective information delivery.

Jane Hodgins | EurekAlert!
Further information:
http://www.fs.fed.us

More articles from Studies and Analyses:

nachricht Obstructing the ‘inner eye’
07.07.2017 | Friedrich-Schiller-Universität Jena

nachricht Drone vs. truck deliveries: Which create less carbon pollution?
31.05.2017 | University of Washington

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

Ultrathin device harvests electricity from human motion

24.07.2017 | Power and Electrical Engineering

Scientists announce the quest for high-index materials

24.07.2017 | Materials Sciences

ADIR Project: Lasers Recover Valuable Materials

24.07.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>