New Tools for an Old Problem: Mechanical renovation of dense clubmoss-infested rangeland

by Tracy Brewer, Research Assistant Professor of Range Science, Joe Skeen Institute for Rangeland Restoration, Dept. of Animal and Range Sciences, Montana State University

Dense clubmoss (Selaginella densa Rydb.) is a low (usually < 1 inch in height), mat-forming, native, perennial forb that behaves as a thin layer of sponge across many acres of rangeland in the United States. It is distributed throughout the Great Plains, Great Basin, and Rocky Mountain region and is most common on mixed-prairie rangeland of Montana, Alberta, Saskatchewan, and North Dakota. Dense clubmoss has no grazing value to cattle and low forage value to wildlife and other livestock. Heavy infestations create dense mats on the soil surface that decrease water infiltration, forage yield, and biological diversity.

Because it impedes the establishment of other plants, dense clubmoss inhibits plant succession and is largely unaffected by changes in the timing, intensity, or frequency of grazing. Prescribed livestock trampling is an effective tool for small, localized infestations, but chiseling (i.e., chisel plowing) has been the most common method for treating large infestations of dense clubmoss.

Some landowners and resource managers, however, consider the high degree of soil disturbance caused by chiseling unacceptable. After chiseling, the ground surface is too rough to traverse by horseback or in a vehicle, and the physical appearance of recently chiseled rangeland is aesthetically displeasing to many people.

The Tar King Plant-O-Vator and the Lawson Aerator are two alternative implements currently endorsed by some Montana landowners. These new mechanical treatment options purportedly cause less soil disturbance than chiseling, but the efficacy of these new methods has not been evaluated experimentally. In response, researchers at Montana State University in Bozeman have implemented a study to evaluate both the Tar King Plant-O-Vator and Lawson Aerator for rehabilitating dense clubmoss-infested rangeland. The study is being conducted on dense clubmoss-infested, mixed-prairie rangeland on the American Fork Ranch, a working cattle ranch located approximately 17 miles south of Two Dot. The study is comparing the effectiveness of the Tar King Plant-O-Vator, Lawson Aerator positioned at a 5 degree angle, and Lawson Aerator positioned at a 10 degree angle. Spring versus fall treatments are also being compared. Fall treatments were applied in October 2003 and spring treatments were applied in April 2004.

Short-term results indicate that spring treatment reduced dense clubmoss ground cover more and fostered more grass production than fall treatment. Spring treatment reduced dense clubmoss ground cover from 48% before treatment to 24% in July 2004, while fall treatment reduced dense clubmoss ground cover from 48% to 31%. Grass production in July 2004 was 405 lbs/acre following spring treatment, compared to 341 lbs/acre following fall treatment.

Dense clubmoss ground cover was reduced from 48% to 25% and 23% following treatments with the Tar King Plant-O-Vator and Lawson Aerator positioned at 10 degrees, respectively, while dense clubmoss ground cover declined from 48% to 34% following treatment with the Lawson Aerator positioned at 5 degrees. In the short-term, grass production was reduced by all three treatments when compared to untreated areas. Untreated areas produced 606 lbs/acre of grass, while treatments with the Tar King Plant-O-Vator, Lawson Aerator positioned at a 5 degree angle, and Lawson Aerator positioned at a 10 degree angle resulted in 395, 402, and 323 lbs/acre of grass, respectively.

In general, spring treatment may benefit dense clubmoss-infested rangeland more than fall treatment the first summer following application. Although the Lawson Aerator positioned at 10 degrees reduced dense clubmoss ground cover relatively well, it caused the most disturbance to the ground surface, resulting in reduced grass production. Treatment with the Tar King Plant-O-Vator appeared to provide the best balance by reducing ground cover of dense clubmoss relatively well and producing similar grass yield as the Lawson Aerator positioned at 5 degrees. Data will be collected on this site again in July 2005 to evaluate responses two growing seasons after treatments are applied, which will ultimately be more informative for evaluating the efficacy of these techniques.

This information is for educational purposes only. Reference to commercial products or trade names does not imply discrimination or endorsement by the Montana State University Extension Service.

Return to regular view	Text-only	Updated: 11/08/2005