‘Green glacier’ arrives in South Dakota
A“green glacier” is moving into South Dakota. That’s the term range management and conservation specialists are using to describe the spread of juniper and cedar trees, says Pete Bauman, South Dakota State University Extension range field specialist. “The cedar invasion appears to be primarily a product of removal of fire from the grasslands,” Bauman says.
Two types of juniper species are a concern in South Dakota: the Rocky Mountain juniper and the eastern red cedar. The Rocky Mountain juniper is believed to be native to the Missouri River Breaks region and the Black Hills, while the eastern red cedar is thought to be mostly introduced. The juniper is more of a bushy-type of plant, while the cedar takes on more of an upright growth form typical of a pine or spruce tree. Eastern red cedars are the common tree used in shelterbelts and wildlife habitat plantings.
Although juniper may be expanding in density and area in several regions of south-central South Dakota, it is the eastern red cedar that appears to be the species of dominant statewide concern because of its popularity, hardiness in plantings and appeal to birds, which are the primary disperser of its seeds.
Escaped or volunteer cedar trees likely occur in every county of South Dakota. Aside from initial plantings, volunteer trees are generally found in fencerows and under power lines, and in hardwood shelterbelts, pastures, Conservation Reserve Program land and other areas.
What can be done? “Biologically, cedars are tough,” Bauman says. “Their waxy coating and relative resilience can make them a formidable foe. Chemical applications are generally not practical, have mixed results and can impact non-target vegetation.” However, cedars are susceptible to two basic control methods.
1. Cedars lack the ability to resprout. While cedar saplings might cover a pasture, once they’re dead, they’re dead. Killing a small cedar can be done easily through mechanical control: either via chainsaw, hand loppers, hand saws, ATV-mounted shears or larger carbide cutters mounted to skid-steer loaders. When mechanically controlling cedar, it is necessary to remove the tree below the lowest branch, so care should be taken if using rotary mowers.
2. Cedars are susceptible to fire. Fire can be an effective tool when applied to saplings less than 3 or 4 feet tall. The key to fire use is to ensure an adequate fuel load to create enough heat to kill the tree. This is best accomplished with resting the pasture for a full season prior to the burn. While larger trees can be killed with fire as well, these types of fires generally require implementation during hotter and dryer conditions, usually early spring. Burning in these conditions of increased fire risk requires experience and methods that most landowners do not have, so caution should be exercised, Bauman says.
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