Navigation Links
Increase in hemlock forest offsetting effect of invasive hemlock woolly adelgid for now

NEWTOWN SQUARE, Penn., Jan. 22, 2014 Despite the accumulating destruction of a non-native invasive insect called the hemlock woolly adelgid, hemlock forests in the eastern United States appear to have held their own for now, according to new research by the U.S. Forest Service.

The key word is "appear," said Talbot Trotter, the study's lead author and a research ecologist with the U.S. Forest Service's Northern Research Station.

In many regions, particularly in the southern Appalachians, the loss of hemlock to hemlock woolly adgid has been devastating. However, when Forest Service scientists used regional Forest Inventory & Analysis (FIA) data to get a big picture view of the status of hemlock in the eastern U.S., the results surprised them. "In analyzing FIA data from the 1950s through 2007, we expected to see a more pronounced impact on hemlock stands," according to Trotter.

The data suggests that increasing tree density associated with the past century of reforestation and succession in the eastern U.S. may have offset the negative impacts of the adelgid at the regional scale.

The study, "Changes in the regional abundance of hemlock associated with the invasion of hemlock woolly adelgid," was recently published in the journal Biological Invasions and is available at:

A native of Japan, the hemlock woolly adelgid was first detected in Virginia in the 1950s and for decades remained a primarily urban pest. That had changed by 1980, when the effects of infestation began to be evident in forestland within the tree's native range. Hemlock's native range forms a triangle from northern Georgia and South Carolina through the Appalachian Mountains into Pennsylvania, Canada and Minnesota.

Hemlock trees in the United States do not have natural defenses against hemlock woolly adelgid, which coupled with a lack of natural predators has resulted in high levels of tree mortality in the 18 states where it is known to have spread, particularly in southern states. Trotter believes that this study, which is based on forest data through 2007, may have caught hemlock at a tipping point in the balance between losses from hemlock woolly adelgid and increases due to forest regrowth.

"Repeating this analysis as new FIA data becomes available may show if we are beyond a tipping point and are now losing hemlock," Trotter said.

Even if there were continued increases in hemlock abundance in northern climates, where cold temperatures slow damages from hemlock woolly adelgid, the loss of trees in the south is a loss to the species, Trotter said. "Losing trees in the South results in less genetic variation for hemlock," he said.

"Non-native forest insects like the hemlock woolly adelgid are devastating on many levels because trees are so important to a region's culture and economy," said Michael T. Rains, Director of the U.S. Forest Service's Northern Research Station and the Forest Products Lab. "Forest Service research is working hard to more aggressively control non-native insects and make our forests healthier and more resistant to these disturbances."

Co-authors on the study included Randall Morin, a research forester with the Northern Research Station, Sonya Oswalt, a forester with the Forest Service's Southern Research Station, and research entomologist Andrew Liebhold with the Northern Research Station.

The study included data from 432 counties in 21 states: Alabama, Connecticut, Delaware, Georgia, Kentucky, Maine, Maryland, Massachusetts, Michigan, New Hampshire, New Jersey, New York, North Carolina, Ohio, Pennsylvania, South Carolina, Tennessee, Vermont, Virginia, West Virginia, and Wisconsin.


Contact: Jane Hodgins
USDA Forest Service - Northern Research Station

Related biology news :

1. Particulate air pollution leads to increased heart attack risk
2. High-protein diets, like the Dukan diet, increase the risk of developing kidney disease
3. Fetal exposure to nicotine increases long-term risk of obesity
4. New discovery could stimulate plant growth and increase crop yields, researchers say
5. Maternal stress hormones and maternal smoking increase daughters risk of nicotine dependence
6. Including women on convening committees increases women speakers at scientific meetings
7. Potassium current density increased sharply after 2 weeks of NSCs neural differentiation
8. West coast lumber and log exports increased in value, volume in third quarter of 2013
9. Oxygen levels increase and decrease the effectiveness of anti-inflammatory therapies
10. Air pollution and genetics combine to increase risk for autism
11. Genetic mutation increases risk of Parkinsons disease from pesticides
Post Your Comments:
(Date:11/16/2015)... 2015  Synaptics Inc. (NASDAQ: SYNA ), ... announced expansion of its TDDI product portfolio with ... and display driver integration (TDDI) solutions designed to ... TDDI products add to the previously-announced TD4300 ... resolution), and TD4322 (FHD resolution) solutions. All four ...
(Date:11/12/2015)...   Growing need for low-cost, easy to ... paving the way for use of biochemical sensors ... in clinical, agricultural, environmental, food and defense applications. ... medical applications, however, their adoption is increasing in ... emphasis on improving product quality and growing need ...
(Date:11/10/2015)... YORK , Nov. 10, 2015 ... to behavioral biometrics that helps to identify and ... fraud. Signature is considered as the secure and ... the identification of a particular individual because each ... more accurate results especially when dynamic signature of ...
Breaking Biology News(10 mins):
(Date:11/24/2015)... ... November 24, 2015 , ... ... are paramount. Insertion points for in-line sensors can represent a weak spot where ... InTrac 781/784 series of retractable sensor housings , which are designed to tolerate ...
(Date:11/24/2015)... ... November 24, 2015 , ... Creation Technologies would ... named to Deloitte's 2015 Technology Fast 500 list of the fastest growing companies ... FDA-cleared, Class II medical device that speeds up orthodontic tooth movement by as ...
(Date:11/24/2015)... -- Capricor Therapeutics, Inc. (NASDAQ: CAPR ... and commercialization of first-in-class therapeutics, today announced that ... to present at the 2015 Piper Jaffray Healthcare Conference ... The Lotte New York Palace Hotel in ... --> . --> ...
(Date:11/24/2015)... 24, 2015  PDL BioPharma, Inc. (PDL) (NASDAQ: PDLI ... company,s president and chief executive officer, will present at the ... in New York City . The presentation ... 1, 2015 at 9:30 a.m. EST. ... website at least 15 minutes prior to the presentation to ...
Breaking Biology Technology: