Rising Temperatures Permit Expansion of Southern Pine Beetle Into New Jersey

The New Jersey Pinelands are under attack by southern pine beetle. Photo by USDA NCRS.

The New York Times recently ran a front page story about the damaging spread of southern pine beetle through the New Jersey Pinelands. The article included an interview with Dartmouth biologist Matt Ayres, who talked about how rising temperatures allowed the insect pest to thrive in an area where cold winters once killed it.

Ayres’ research on southern pine beetle receives funding from the U.S. Forest Service Southern Research Station (SRS) Forest Economics and Policy  unit as part of a larger project led by SRS research forester Tom Holmes that explores the interactions among climate trends, forest pests, and economics. Support was also provided by a joint grant from the National Institute of Food and Agriculture to Dartmouth and to Brian Sullivan, research entomologist with the SRS Insects, Diseases, and Invasive Plants unit.

“For the overall project, we decided to focus attention on three forest pest species—mountain pine beetle, southern pine beetle, and hemlock woolly adelgid—that are known to be sensitive to climatic stresses and that cause substantial economic impacts by degrading the condition of forest ecosystems and the goods and services they provide,” says Holmes.

The SRS project supported the analysis of forest insects and diseases included in the 2012 National Climate Assessment (NCA), the comprehensive synthesis of the effects of climate change on U.S. forests led and edited by SRS scientist Jim Vose and colleagues.  Building on the NCA analysis,  Dartmouth postdoctoral researcher Aaron Weed, Ayres, and Jeffrey Hicke from the University of Idaho, recently published a paper in the journal Ecological Monographs reviewing current understanding of climatic effects on 27 insects and 22 diseases that are notable agents of disturbance in North American forests.

Reviewing almost 500 scientific journal articles published over the past 60 years, the authors provide a comprehensive review of known effects of climate change on the forests of North America. They note that many forests are growing faster, with some actually less susceptible to forest pests. In other areas such as the New Jersey Pinelands, warming temperatures allow aggressive pests to enter newly susceptible forests.

Weed and fellow authors note that changing conditions can be a particular challenge in areas where managers have little previous experience dealing with the aggressive pests they’re now facing and where past practices (“hands-off” forest management) or public perception of thinning and pest suppression may prevent managers from taking needed actions.

In a recent NPR radio interview, Weed noted that southern pine beetle would probably move farther north, eventually to the coastal pinelands on Long Island and Cape Cod. In the New Jersey Pinelands, the damage thus far was highest in 2010 when beetles killed trees across 14,000 acres. Since the forest is on flat land, it’s hard to see the effects except from the air, but the beetles attack thousands of new acres every year and public interest is growing.

“The largest forest on the Eastern Seaboard, the New Jersey Pinelands lie within 100 miles of 50 million people and above the aquifer that provides water to many of those people,” write the authors in the recent paper. “Given the natural population dynamics of southern pine beetles and the continued absence of lethal winter temperatures, the forest has entered a new phase when the southern pine beetle will influence all aspects of forest ecology and management.”

Read the full text of the article and the Dartmouth Now article about the research.

Watch “A Story About a Beetle,” a documentary about southern pine beetle featuring Dartmouth and SRS researchers and others.

For more information, email Tom Holmes at tholmes@fs.fed.us

Access the latest publications by SRS scientists.