A 35-year old loblolly pine stand that has been thinned and burned multiple times. Photo by David Stephens, Bugwood.org.
Seventeen percent of the world’s industrial roundwood comes from U.S. forests – and southern pine forests are among the most productive in the country. Pine plantations in the South often anchor local and regional economies while providing ecosystem services such as clean water and air, and countless recreation benefits.
“Forests are an integral part of the South’s ecology and economy,” says U.S. Forest Service scientist Kier Klepzig. “However, there is a general perception that forest health is declining.” Klepzig recently coauthored a study on how landowners and managers in the southeastern U.S. regard forest stand health. Published in the Journal of Forestry, the study was led by University of Georgia (UGA) postdoctoral researcher David Coyle, and forest ecologist and associate professor Kamal J.K. Gandhi.
Via email and mail, the scientists surveyed more than 4,600 forest landowners and managers in Florida, Georgia, and South Carolina – three of the major pine-growing states. Overall, 28 percent of the landowners and managers responded. About half the respondents said their pine stands were healthy; only 11 percent reported high levels of pine mortality within the last year.
Since the 1950s, scientists and managers have occasionally noticed dead or dying pine stands, and the phenomenon has recently been dubbed southern pine decline, or SPD. Scientists have found zero evidence of widespread SPD, but on a local scale, SPD can affect loblolly pine and occasionally other pine species. Less than 30 percent of respondents were aware of SPD.
SPD appears to be caused by a combination of factors, including drought, poor growing conditions, and insect or fungal diseases. However, there seem to be a number of causes for perceived declines in the health of pine stands. The most destructive insect, which happens to be a native, is the southern pine beetle. The beetles are about the size of a grain of rice and often attack overstocked loblolly pine plantations.
Thinning crowded stands is the best way to prevent southern pine beetle infestations, and the survey revealed that landowners were quite willing to thin forests. Landowners in Florida and South Carolina had already been invited to participate in the Southern Pine Beetle Prevention Program, a Forest Service-funded program that helps pay for thinning and other silvicultural treatments. The program has funded preventive silvicultural treatments on 1.2 million acres of southern pine forests.
The Forest Service is also embarking on a thinning project in the Chattahoochee-Oconee National Forests. Although not related to the most recent study, the project builds on earlier research on sustaining healthy forests and will thin crowded loblolly pine stands across 1,465 acres of national forest. The project is slated to begin in 2017.
“Thinning and other traditional, standard management techniques such as prescribed burning and removing competing vegetation are best,” says Klepzig. “We found that most landowners and managers understand how beneficial these practices are.”
Collectively, the landowners and managers who participated in the survey manage almost 4 million acres of land. Survey participants — most of whom were white males in their early 60s — were identified with the help of the Florida Forest Service, the Georgia Forestry Commission, and the South Carolina Forestry Commission.
“Most respondents were aware of the overall health of their pine stands,” says Gandhi, who leads the Gandhi Forest Ecology Lab at UGA . “Less than 5 percent were not sure whether or not pine trees on their land were dead or dying.”
Reports of southern pine decline seem to have been exaggerated, and when pines do decline, it is probably due to a familiar combination of stressors – drought, crowded conditions, or insect invasions. Providing landowners and managers with information on sustaining healthy forests would be valuable, and landowners who participated in the study agreed that they would prefer to receive this information in printed form, from universities and state agencies.
“Proper forest management is integral to reducing stand susceptibility to future pest issues,” says Klepzig. “Our data indicate a favorable outlook for pine health in the Southeast, as landowners are engaged and willing to use recognized management prescriptions.”
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For more information, email Kier Klepzig at kklepzig@fs.fed.us.