Eastern redcedar treatments

By Adam Throckmorton

The “green glacier” is taking over the Great Plains. Eastern redcedar (Juniperus virginiana), otherwise called the “green glacier” has been creeping west over the past century and is at a level of ecological disturbance some equal to the Dust Bowl of the 1930’s.

A critical tool for slowing this “green glacier” is the use of prescribed fire. Researchers are finding prescribed fire, in the right time and place, can slow the advance of eastern redcedar. Just as prescribed fires in western states can reduce fuel loads, mitigate potential future wildfire damage and help restore natural communities, prescribed fires in the Great Plains can act in a similar fashion.

Economically, eastern redcedars reduce the size of valuable grazing land, leading to reductions in stocking rates. Allergies from spring pollen cost residents of the Great Plains upwards of two billion dollars. Reduction in habitat for game birds like grouse and pheasant and beneficial predators like hawks and owls is common in eastern redcedar infested areas. The habitat of the threatened lesser prairie chicken has been reduced by eastern redcedar infestations.

The eastern redcedar can act as a matchstick during wildfires. The disastrous 2012 fires in Oklahoma were partially fueled by eastern redcedar. Eastern redcedar sucks up ground water at a rate higher than other plants, which contributes to more arid conditions in already drought-stricken locations. Eastern redcedar infestations also lead to reduction in plant diversity as nothing grows beneath them.

Most research shows a continuous strategy of prescribed fire on open lands keeps eastern redcedar encroachment in check. Several sources point to the Flint Hills of Kansas and specifically Chase County, where annual spring burning is common, and eastern redcedar is not. These sources cite a rate of yearly or every three to four years as the best burning interval to slow the eastern redcedar invasion. This has been well documented on the Konza Prairie near Manhattan, Kansas. However, prescribed burns only tend to cause mortality on smaller (less than six-foot tall) eastern redcedars, except for exceptional circumstances.

 Conservation Corps of Iowa crew cutting cedars at Pea Ridge National Military Park.

 Conservation Corps of Iowa crew cutting cedars at Pea Ridge National Military Park.

For taller eastern redcedars, mechanical removal is often necessary. Pea Ridge National Military Park, near Rogers, Arkansas, has been conducting large-scale eastern redcedar removal in oak forest understory with a skid-loader and chipper.

Chipped cedar at Pea Ridge National Military Park.

Chipped cedar at Pea Ridge National Military Park.

Another strategy is to cut eastern redcedar trees and leave them on the ground to be consumed in future burning. One pressing question, especially in Oklahoma, is what to do with all the biomass from eastern redcedar removal. These two methods will create fuel for necessary prescribed burning and have lower investment than trying to find markets for cedar wood products.

Prescribed fire aimed at cedar control at Pea Ridge National Military Park.

Prescribed fire aimed at cedar control at Pea Ridge National Military Park.

After large eastern redcedars are removed, it will be time to think about a strategy to keep them from returning. Prescribed fire, so far, has proven to be one of the best strategies. Research has shown keeping within a frequent burn rate continues to reduce the amount of eastern redcedar seedlings, other brushy species and promote prairie grasses. Pea Ridge NMP has been conducting prescribed burns in removal areas within a couple of years of mechanical removal.

Understory recovery two months post-burn at Pea Ridge National Military Park. The exotic plant management team is able to treat tree of heaven seedlings.

Understory recovery two months post-burn at Pea Ridge National Military Park. The exotic plant management team is able to treat tree of heaven seedlings.