Hemlock Trees Dying Rapidly, Affecting Forest Carbon Cycle


ScienceDaily (Mar. 10, 2009) — New research by U.S. Forest Service Southern Research Station (SRS) scientists and partners suggests the hemlock woolly adelgid is killing hemlock trees faster than expected in the southern Appalachians and rapidly altering the carbon cycle of these forests. SRS researchers and cooperators from the University of Georgia published the findings in the most recent issue of the journal Ecosystems.
See also:
Plants & Animals

* Trees
* Nature
* Botany

Earth & Climate

* Forest
* Rainforests
* Exotic Species

Reference

* Coast Douglas-fir
* Conium
* Old growth forest
* Forest

"The study marks the first time that scientists have tracked the short-term effects hemlock woolly adelgid infestations are having on the forest carbon cycle," said Chelcy Ford, SRS ecologist and co-author of the paper.

Eastern hemlock, a keystone species in the streamside forests of the southern Appalachian region, is already experiencing widespread decline and mortality because of hemlock woolly adelgid (a tiny nonnative insect) infestation. The pest has the potential to kill most of the region's hemlock trees within the next decade. As a native evergreen capable of maintaining year-round transpiration rates, hemlock plays an important role in the ecology and hydrology of mountain ecosystems. Hemlock forests provide critical habitat for birds and other animals; their shade helps maintain the cool water temperatures required by trout and other aquatic organisms in mountain streams.

Scientists conducted the study in mixed hardwood forests along the edges of two streams at the SRS Coweeta Hydrologic Laboratory, a 5,600-acre research facility and experimental forest in the Nantahala Mountain Range of western North Carolina.

Researchers compared rates of decline of adelgid-infested hemlock trees to a small number of girdled (severely wounded the bark of a tree to initiate tree mortality) trees that were not infested. Researchers tracked changes in the carbon cycle of these hemlock stands over a 3-year period. Scientists measured components of the forest carbon cycle – including tree growth, leaf litter and fine root biomass, and soil respiration – over the 3-year period.

"While we expected that girdled trees would decline quickly, we were surprised to find that hemlock declines just as quickly from adelgid infestation," said Ford. "This research shows that hemlock woolly adelgid infestation is rapidly impacting the carbon cycle in these tree stands. The study also supports the widely held belief that adelgid-infested hemlock trees in the South are declining much faster than the reported 9-year decline of some infested hemlock trees in the Northeast."

The study showed, among other things, that very fine roots in the girdled and hemlock woolly adelgid-infested plots declined by 38 percent and 22 percent, respectively, during the 3-year period. In addition, in the first year after girdling and infestation, researchers found soil respiration was approximately 20 percent lower than they expected.

The authors suggest that infrequent frigid winter temperatures in the southern Appalachians may not be enough to suppress adelgid populations. The authors believe this could be one explanation of why infested hemlocks appear to be declining faster in the South than in the Northeast. The authors also point out that other tree species are quick to occupy the space given up by their dying hemlock neighbors.

"Perhaps because of increased light in the canopy and reduced competition for soil nutrients and water, other species are already increasing their growth," said Ford. "We'll continue to monitor this, but, it's still too early to predict just how different these forests will look 50 or 100 years from now."

Journal reference:

1. April E. Nuckolls. Hemlock Declines Rapidly with Hemlock Woolly Adelgid Infestation: Impacts on the Carbon Cycle of Southern Appalachian Forests. Ecosystems, DOI: 10.1007/s10021-008-9215-3

Adapted from materials provided by Southern Research Station - USDA Forest Service, via EurekAlert!, a service of AAAS.
Email or share this story:
Need to cite this story in your essay, paper, or report? Use one of the following formats:
APA

MLA
Southern Research Station - USDA Forest Service (2009, March 10). Hemlock Trees Dying Rapidly, Affecting Forest Carbon Cycle. ScienceDaily. Retrieved May 4, 2009, from http://www.sciencedaily.com­ /releases/2009/02/090226122730.htm
Ads by Google
Advertise here
Hemlock Woolly Adelgid
Find Info & Solutions For Treating The Hemlock Woolly Adelgid
Arborjet.com/hemlockadelgid
Save Trees
Join Coke in helping the planet by recycling & completing the cycle!
LivePositively.com/JoinUs
Tree borer
Systemic Insecticide for Healthy, Disease Resistant Trees. Buy Online
www.TreeRx.com
Green Trees
Refi Now. 1 Form, 4 Free Quotes. Fixed Mortgage Rates as Low as 4.4%
Loans.Bills.com
Hemlock Trees
Everything to do with Hemlock Trees items.
Yahoo.com
Related Stories
Loss Of Hemlocks Will Affect Water Dynamics In Southern Appalachian Forests (July 12, 2007) — Forest Service research has provided the first estimates on the impact the loss of eastern hemlock will have on the water dynamics of the southern Appalachian mountains. Eastern hemlock, a keystone ... > read more
Fungal Factories May Save Hemlock Forests (Jan. 26, 2007) — From Georgia to Maine, eastern hemlock trees are succumbing to an exotic pest, hemlock woolly adelgid. The adelgid has no natural predators in North America, but some native fungi kill it. A ... > read more
Japanese Beetle May Help Fight Hemlock-killing Insect (Sep. 17, 2007) — The eastern hemlock, a tall, long-lived coniferous tree that shelters river and stream-side ecosystems throughout the eastern United States and Canada, is in serious danger of extinction because a ... > read more
Climate Change Not The Only Factor Controlling Distribution Of Plant Species (July 12, 2006) — Biogeographers have long recognized that the spatial distribution of plant species, at a coarse resolution, mainly reflects each species' climatic requirements. However, few studies have carefully ... > read more
'Live Fast, Die Young' Applies To Forests, Too (Apr. 19, 2005) — In the most recent issue of Ecology Letters, Stephenson and van Mantgem show that birth and death rates of trees vary in parallel with global patterns of forest productivity. The faster turnover of ... > read more
Search ScienceDaily
Number of stories in archives: 44,032
Find with keyword(s):

Enter a keyword or phrase to search ScienceDaily's archives for related news topics,
the latest news stories, reference articles, science videos, images, and books.
Ads by Google
Advertise here
Crystal Donor Walls
Beautiful and elegant donor walls etched in crystal. Stunning!
www.claruscrystal.com
Grow Hemlock at Home.
Rooted cuttings, very easy to do. Homemade plant propagation system.
FreePlants.com
Hemlocks At Gurney's
Shop For Hemlock Hedges & More At Gurney's - Free $25 Coupon.
www.Gurneys.com

Just In:
Isolated Birds Evolve 'Normal' Species Song
First Trillionth Of A Second After Big Bang
Halving Carbon Emissions To Stabilize Warming?
Earth Still Recovering From A Glacial Hangover
Human Brain Can Recognize Objects Much Faster
Dolphins Maintain Constant Visual Vigilance
World's Fastest Camera: New Type Of Imaging
Missing Planets: Destructive Stellar Tides
Missing Planets: Destructive Stellar Tides
Science Video News
Can Carbon Dioxide Be A Good Thing?
A physicist from Colorado State University and his colleagues from the North American Carbon Program (NACP) have discerned and confirmed the. ... > full story

* Environmental Scientists Find Tree Combo For Carbon Sequestration
* Arborists Catalogue Tree Details To Measure Their Impact On A City
* Plant Scientists Graft Apple Trees to Select Disease-Resistant Traits
* more science videos

Breaking News
... from NewsDaily.com

* Trial by fire: New antibody method gets big test
* WHO says existing vaccine little use against new flu
* New flu virus may be a real mongrel: study
* World fights new flu virus with latest science
* NASA to begin layoffs as shuttle retirement nears
* more science news

In Other News ...

* Boston Globe will not file "warn" notice on Monday
* Obama seeks tax changes for U.S. firms overseas
* Nepal in political turmoil after PM quits
* U.S. home sales suggest housing bottom near
* WHO head indicates full flu pandemic to be declared
* Car industry shake-up looms as Fiat eyes Opel
* As Democrat, Specter leads in home state: poll
* Obama to meet Afghan, Pakistan leaders on strategy
* more top news

Contact Information

ScienceDaily
1 Research Court
Suite 450
Rockville, MD 20850

Tel/Fax: (240) 454-9600
Email: editor@sciencedaily.com

Copyright © 1995-2009 ScienceDaily LLC — All rights reserved
Comments: 0
Votes:34