Garden Variety: Kansas’ only native evergreen can cause problems
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Eastern red cedar is a common tree in landscape plantings and in the wild with its evergreen nature making it most noticeable in the winter months. The tree is the only evergreen native to Kansas, but it is problematic in unmanaged grasslands where it can displace native plants and affect the environment.
Eastern red cedar (Juniperus virginiana) is slow-growing, tolerant of a wide range of soil conditions, drought tolerant, and has few pests. Its needles (leaves) are scale-like and flattened around the stems instead of being elongated like pine or spruce needles. Trees are typically columnar to pyramidal in shape in early years, with growth spreading and becoming more irregular as they grow and age. They are common in fencerows, roadsides and unmanaged grasslands, growing to about 40 feet at maturity.
There are male and female eastern red cedars. Female trees produce hard, blue-gray cones that are about the diameter of a pea. The cones are eaten by birds and mammals and are an important winter food source for these animals. Trees also provide shelter to a variety of wildlife throughout the year.
Throughout much of the last century, eastern red cedars have been planted as windbreaks and shelterbelts to protect homes, crops and livestock, as well as to provide food and shelter for wildlife. Pine and spruce were added to the mix for a period but have proved to be less reliable, and many of those species have succumbed to disease in Kansas.
There are also a few cultivated varieties of red cedar that are widely planted in managed landscapes. The Canaert juniper variety maintains its green color through the winter better than most red cedars and is a female clone with heavy cone production. Taylor juniper is a narrow, columnar red cedar selection that grows to about 15 feet tall by 4 feet wide at maturity.
The drawbacks of red cedar
The problem with red cedars is that they are being allowed to proliferate in grassland areas, where they displace native plants and the wildlife species that live in them. They also become a fire hazard with age. This is mainly a management issue, as young red cedars are easily controlled.
Prairie fires kept red cedar in check until people kept prairie fires in check. According to the Kansas Forest Service, from 1965 to 2018, “the volume of eastern red cedar in Kansas has increased more than 23,000 percent within its native range.” The forest service also notes that red cedar has not become a nuisance in parts of Kansas where controlled burns are common, such as the Flint Hills.
The fire hazard is another issue. Although red cedars are easily controlled by fire in the first five to 10 years of their life, older trees are problematic. Large red cedars contain volatile compounds that make them burn extremely hot, raise the fire height and produce ember showers that make fires more difficult to control.
Physical removal of large red cedars takes a lot of time and can be daunting on large acreages but can be an effective method of control. Red cedars cannot resprout from stumps if all foliage is removed, so they can simply be cut off at ground level.
Young red cedars are easily kept in check with controlled burns, physical removal or chemical treatment. A five- to 10-year burn cycle is sufficient for red cedar control, with the interval depending on the region and weather cycles.
Researchers are looking at the development of male clones of eastern red cedar for use in windbreaks. There is also interest in uses for tree biomass after removal.
— Jennifer Smith works in regulatory horticulture and has worked as a horticulturist for various government entities. She has experience in landscape design and maintenance and as an educator.