ALLERGY, RESPIRATORY
Obesity May Raise Kids' Allergy Risk
Asthmatics Who Quit Smoking May Reverse Lung Damage
Air Quality Better in Northeast, Midwest
ALTERNATIVE MEDICINE
Fish Oil's Benefits Remain Elusive
Acupuncture Eases Breast Cancer Treatment Side Effects
Indigo Ointment Benefits Psoriasis Patients
ANIMAL CARE
Rest Easy. When It Comes to Swine Flu, Your Pet Is Safe
Beware of Dog Bites
Safe Toys for Dogs
BONES & JOINTS
Active Young Women Need Calcium, Vitamin D
Most Kids With Type 1 Diabetes Lack Vitamin D
Studies Struggle to Gauge Glucosamine's Worth
CANCER
Yoga Eases Sleep Problems Among Cancer Survivors
Selenium, Omega-3s May Stave Off Colorectal Cancer
Family History Key Player in Brain Cancer Risk
CAREGIVING
Recession Scrambling Health Spending in U.S.
Few Hospitals Embracing Electronic Health Record Systems
With Alzheimer's, Health-Care Costs Could Triple
CIRCULATORY SYSTEM
Varicose Veins May Mask Larger Problem
Health Tip: Are You Anemic?
Secondhand Smoke Quickly Affects Blood Vessels
COSMETIC
Science May Banish Bad Hair Days
What to Do If You Have Unsightly Veins
With Psoriasis, the Internet May Offer Hope
DENTAL, ORAL
Scientists Find Gene for Tooth Enamel
Holistic Dentistry-My View
Study Links Osteoporosis Drugs to Jaw Trouble
DIABETES
Laughter May Lower Heart Attack Risk in Diabetics
Vitamin K Slows Insulin Resistance in Older Men
Insulin Resistance Tied to Peripheral Artery Disease
DIET, NUTRITION
Meat Additives May Be Dangerous for Kidney Patients
Eating Lots Of Vegetables, Olive Oil May Extend Life
Vitamin D May Help Keep Aging at Bay
DISABILITIES
Could Your Cell Phone Help Shield You From Alzheimer's?
Review Finds Marijuana May Help MS Patients
ENVIRONMENTAL HEALTH
Staying Slim Is Good for the Environment
Air Quality Better in Northeast, Midwest
Arsenic in Drinking Water Raises Diabetes Risk
EYE CARE, VISION
Don't Lose Sight of Halloween Safety
Contact Lens Cases Often Contaminated
Decorative Halloween Eye Lenses May Pose Serious Risks
FITNESS
Mom and Baby Alike May Benefit From Exercise
Will the Wii Keep You Fit?
Fitness Fades Fast After 45
GASTROINTESTINAL PROBLEMS
Soothing Imagery May Help Rid Some Kids of Stomach Pain
Gum Chewing May Speed Colon Surgery Recovery
Intestinal Bacteria Trigger Immune Response
GENERAL HEALTH
How Weight Loss Can Help the Heart
Sun, Smoke, Extra Weight Add Years to Skin
Olde Time Medicine Therapy May Prevent Alcoholic Relapse
HEAD & NECK
Ski Helmets Encouraged for All
Many Children Will Outgrow Headaches
Zen May Thicken Brain, Thwart Pain
HEALTH & TECHNOLOGY
Imaging Sheds Light on How Acupuncture Works
The Internet Is Becoming One-Stop Shopping for Health Help
Using Light Therapy to Silence Harmful Brain Activity
HEARING
Noise Hurts Men's Hearing More, Study Shows
Summer Sounds Can Lead to Hearing Loss
HEART & CARDIOVASCULAR
Soy Protein Doesn't Lower Cholesterol
Vigorous Exercise Cuts Stroke Risk for Men, Not Women
Fondness for Fish Keeps Japanese Hearts Healthy
INFECTIOUS DISEASE
Poor Restroom Cleaning Causes Cruise-Ship Sickness
Dry Weather Boosts Odds of Flu Outbreaks
Surgical Masks Could Prevent Flu, Maybe
INFERTILITY
Obesity May Affect Fertility in Young Womene
KID'S HEALTH
Protect Your Kids From Swine Flu While at Camp
Standard IQ Test May Underestimate People With Autism
Scorpion Anti-Venom Speeds Children's Recovery
MEN'S HEALTH
Physical Activity May Prolong Survival After Colon Cancer
Lots of Sex May Prevent Erectile Dysfunction
Eating Fast Until Full Triples Overweight Risk
MENTAL HEALTH
A Simple 'Thank You' Brings Rewards to All
Brain Scans Show How Humans 'Hear' Emotion
Common Social Groups and Race, Seem to Help People Relate
PAIN
'Cell Phone Elbow' -- A New Ill for the Wired Age
Tai Chi May Help Ease Fibromyalgia
Acupuncture, Real or Fake, Eases Back Pain
PHYSICAL THERAPY
PREGNANCY
Mom's Extra Pregnancy Pounds May Raise Child's Heart Risks
Music of Mozart Soothes the Preemie Baby
Pregnant Women Exposed To Certain Pollutants Could Lower Childs IQ
SENIORS
Money May Matter, Health-Wise, in Old Age
Friends, Not Grandkids, Key to Happy Retirement
Common Antioxidant Might Slow Parkinson's
SEXUAL HEALTH
SLEEP DISORDERS
Exercising Throat Muscles May Relieve Sleep Apnea
Lose Weight, Sleep Apnea May Improve
Meditation May Help Put Primary Insomnia to Bed
WOMEN'S HEALTH
Exercise Boosts Bone Density in Breast-Feeding Moms
Prenatal Stress May Boost Baby's Asthma Risk
Natural Oils Help Lower Body Fat For Some
Add your Article

Old-Growth Forests Dying Off in U.S. West

By Steven Reinberg
HealthDay Reporter

THURSDAY, Jan. 22 (HealthDay News) -- Trees in old-growth forests in the Western United States are dying at twice the rate they were a few decades ago, and experts suspect regional warming is to blame.

The report, led by the U.S. Geological Survey (USGS), found that the increase in tree deaths has included trees in a variety of forests, elevations and sizes. Species have included pine, fir, hemlock and other coniferous trees. In addition, the rate of new tree growth has not changed, according to the report in the Jan. 23 issue of Science.

"If current trends continue, forests will become sparser over time, and average tree ages will decrease by half," study co-author Phillip van Mantgem, a USGS research ecologist, said during a teleconference Wednesday.

In the future, forests will store less carbon than they do now, van Mantgem said. "It introduces the possibility that Western forests could become net sources of carbon dioxide, further speeding up the pace of global warming," he explained.

In addition, fewer trees could result in a loss of habitat for animals that depend on old-growth forests, van Mantgem said, and there might also be an increased risk of forest fires, with increasing drought and more fallen trees.

To determine the causes of increased tree death, the researchers considered problems in the forest themselves, such as overcrowding. "Every way we cut the data and examined it, it looks like internal dynamics are not a significant source of the increase in mortality rates," Nathan Stephenson, a USGS research ecologist and co-author of the study, said during the teleconference.

The researchers also looked at external causes, such as air pollution. However, they concluded that these were unlikely causes of the troubling trend, Stephenson said.

"What we were left with was temperature," he said. "Increasing temperature was correlated with the increase in mortality rates."

Rising temperatures in the Western United States have changed weather patterns, Stephenson said. Summers are getting longer, increasing drought conditions. "It is possible that trees are under more drought stress," he said.

Moreover, warmer temperatures favor an increase in insects and other organisms that feed on trees, he said.

"Projections for the future are for continued warming, and even an accelerated rate of warming," Stephenson said. "It's very likely that mortality rates will continue to rise."

Thomas Veblen, a professor of geography at the University of Colorado at Boulder and another co-author of the study, noted during the teleconference that the findings are consistent with other ecological changes brought on by global warming.

"These include increased wildfire activity across the Western U.S., as well as bark beetle outbreaks that are occurring at unprecedented levels across Western North America," Veblen said.

He noted that these changes in climate necessitate a reevaluation of policies on how forests are managed, including new ways of dealing with wildfires and limiting development.

One critic of the concept of global warming, Steven Milloy, publisher of JunkScience.com, does not think that tree deaths have an effect on climate change.

"If they are trying to add on to climate alarmism, their paper is way short of that," Milloy said. "To say tree death is going to contribute to global warming is extremely debatable. It's all kind of silly to me."

However, two papers in the Jan. 22 issue of Nature describe other changes occurring as the earth's temperature rises.

Seasons now arrive two days earlier than they used to, one study from scientists at the University of California, Berkeley, and Harvard University concluded. Not only have average worldwide temperatures been rising for the last 50 years, according to the report, but the hottest day of the year has shifted to almost two days earlier.

And the other study found that temperatures in Antarctica have increased about half a degree in the past 50 years. The warming of Antarctica is related to changes in atmospheric circulation and declines in sea ice in the pacific region of the southern polar ocean, the University of Washington researchers concluded.

More information

For more information on climate change, visit the U.S. Environmental Protection Agency .



SOURCES: Jan. 21, 2009, teleconference with: Phillip van Mantgem, Ph.D., U.S. Geological Survey (USGS) research ecologist, Arcata, Calif.; Nathan Stephenson, Ph.D., USGS research ecologist, Three Rivers, Calif.; and Thomas Veblen, Ph.D., professor, geography, University of Colorado at Boulder; Steven Milloy, publisher, JunkScience.com; Jan. 23, 2009, Science; Jan. 22, 2009, Nature

Last Updated: Jan. 22, 2009

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