So within the first year after planting, foresters recommend spraying a herbicide to knock back the weeds and give the pines the chance to rise above the crowd.
Herbicides have long been used to control hardwoods in pine forests, said David Dickens. And for a number of years now, an early, once-over spray to control smaller weeds has become a standard management practice.
Worth the Extra Cost
"It's particularly useful here in the South," Dickens said, "where we get such lush vegetative growth. We've found it can enhance growth enough to warrant the additional expense."
Does the added use of herbicide pose an added threat to people and wildlife?
Not really, Dickens said.
"In general, the herbicides we use now are very safe, to the environment and to ourselves, if we take care when we handle and use them," he said. "And we use them only once or twice in the life of the forest, which may be 20-30 years or more."
Use Herbicide Early
Foresters often recommend using a herbicide to control herbaceous weeds either in preparing the planting site or within the first year after planting.
Then within three to five years, they may recommend another application to control the hardwoods that compete, as the weeds did earlier, for the moisture and nutrients in the soil.
Later on, as the trees get tall enough, foresters use fire to control the competing vegetation. Each practice is geared to giving the pines an edge over the other plants.
Herbicides are simply a management tool in forestry, Dickens said. And how much management a forest needs depends on what the landowner wants to do with his land.
"At one extreme is a highly managed forest with heavy applications of fertilizer, pesticides and herbicides so there's nothing out there growing but pine trees," he said.
"We do that on some research plots, but it's often not economical in general use," he said. "At the other extreme is an unmanaged, green jungle. What you generally want is somewhere in-between those extremes."
Giving pines an edge but allowing some hardwoods and other plants in a forest is not only cost-effective, Dickens said, but can also open the forest to more wildlife species and other benefits.
Managing toward either extreme would narrow the range of wildlife that would find the forest attractive. "If you manage the forest just for one wildlife species such as the spotted owl or red cockaded woodpecker," Dickens said, "you manage to hurt other species."
(Dan Rahn is a news editor with the University of Georgia College of Agricultural and Environmental Sciences.)