Dense cedar invasion near Missouri River west of Platte, S.D.
The issue of cedar tree invasion into South Dakota's rangelands tends to be a regional conversation, explained Pete Bauman, SDSU Extension Range Field Specialist.
"Those in the south central and southeastern portions of South Dakota understand well the challenges in controlling these invasive trees. There is generally broad agreement among most resource professionals that these trees are in fact changing our landscape in a negative way. However, forging a definitive path toward addressing the issue becomes a dilemma as best management practices are not always clear," Bauman said.
The reason? Bauman said not only is control difficult, but the cedar tree has a long history of positive uses in shelterbelts and wildlife plantings.
"The issue becomes complicated by the debate over whether the appeal cedars have for humans and certain wildlife outweigh their overall threats to the landscape," Bauman said.
This winter, during the Society for Range Management annual meeting, a symposium was held on cedar control in the Great Plains, range professors, economists and social scientists from across the southern and central plains spoke on the overwhelmingly negative impact these species have on the plains. "The message was clear - juniper and cedar are spreading rapidly, the wave is heading north, they are creating changes on the landscape that are primarily negative, and the Dakota's are the cedar frontier," Bauman said.
In a nutshell, Bauman said, the expansion of these species across the plains is now being dubbed the 'Green Glacier,' and the reality is that this expansion will continue to impact rangeland productivity and management.
"The most challenging message to come from recent research is that cedar invasion appears to be primarily a product of removal of fire from the grasslands," he said. "While it is true that active planting of cedars will continue to create unnatural source populations, land management practices such as grazing do not significantly contribute to the spread of the plant."
Simply put, Bauman explained that the grand expansion of cedars is the by-product of active planting and fire exclusion. "Where fire has been preserved or re-introduced as a management tool, the trees are generally controlled regardless of the other grassland management practices that occur," he said.
Rocky Mountain & Eastern Red Cedar
In South Dakota there are two types of cedars which create concern, the Rocky Mountain juniper (Juniperus scopulorum) and the eastern red cedar (J. virginiana). 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.
For those unfamiliar with the difference, Bauman explained that the juniper is more of a bushy-type 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 utilized 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 Bauman said 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.