Fort McCoy News January 24, 2014

Wet-blade mowers help maintain training areas

Fort McCoy's firing points support multiple types of training. Typical training includes dismounted maneuvers, battalion-sized bivouac activities, rotary-wing aircraft operations and wheeled- and tracked-vehicle live-fire maneuvers. Given the complexity of how firing points are used, the Range and Training Lands Assessment (RTLA) program assesses the potential training capability at each firing point and identifies issues that restrict that capability.

Photo 1 for wet-blade mower article
Firing Point 402 pre-wet-blade-mower treatment in October 2011.
Contributed photo

Helicopters, for example, engage in landing zone – pick-up zone (LZ-PZ) training exercises at firing points. RTLA evaluates each firing point to ensure that open maneuver areas are free of training obstructions such as encroachments from woody shrubs and saplings. If tree or shrub height exceeds 18 inches, a safety hazard exists that precludes helicopter landings in the area.

Once restrictions are identified by RTLA, the Land Rehabilitation and Maintenance (LRAM) Program, executes an environmentally balanced solution. To remedy the shrub-encroachment problem, the LRAM program uses a newly acquired mowing implement — a wet-blade mower.

A wet-blade mower is used to mow and treat re-sprouting shrubs.

The wet-blade system has the appearance of a brush mower with the addition of an attachment that handles the herbicide. The wet-blade system is designed to send a calibrated amount of herbicide down the mower blade as the blades are engaged to evenly treat the target area.

Only plants cut by the mower blade receive the herbicide. To avoid herbicide exposure to non-target herbaceous species, the LRAM program treated parcels in the late fall months when herbaceous species are dormant and less susceptible to the herbicide.

The RTLA program monitored both the effectiveness of the treatment on the woody vegetation that was cut and the response of native herbaceous species in regard to the treatment regime. Assessments were conducted from 2009 to 2012.

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Firing Point 402 post-wet-blade-mower treatment in September 2012.
Contributed photo

With notebook in hand and a digital camera to take photos of current land conditions, RTLA Coordinator Susan Vos, a contract employee supporting the Directorate of Plans, Training, Mobilization, and Security at Fort McCoy, visited treated firing points in May 2009.

Vos looked through each treatment parcel to assess the effectiveness of the wet-blade treatment in controlling the woody shrubs. She took note if stems were re-sprouting and noted if there were areas where the herbicide applied killed more than just the targeted woody shrubs.

In August 2009, Vos returned to the field with her crew to assess each treatment parcel in a more systematic way. The vegetation in August was more mature. The native warm-season grasses dominated over the cool-season grasses, and spring flowers had gone to seed.

One crew member measured the frequency of woody stems. When a shrub stem was encountered, the observer determined whether the woody stem was alive or dead. If the stem was alive, it was determined if it was a new seedling or a re-sprout.

Vos analyzed the data to determine if the treatment was killing woody stems and preventing the release of new shrub seedlings.

Meanwhile, other RTLA crew members assessed the vegetation by randomly placing a small square quadrant (quad) throughout treatment parcels. RTLA members identified each plant rooted within the quad. By studying the vegetation community, Vos was able to determine if a shift in the vegetation structure occurred.

Photo 3 for we-blade mower article
A wet-blade mower is used to help keep training areas clear of
Contributed photo

This is an important piece of information, according to Vos, that defines the success of the treatment in controlling woody shrub growth without negatively affecting non-target native vegetation.

Each plant holds a niche in the vegetation community, and each plant tells a story about where the land is along the continuum of recovery (especially after a major change such as mowing with herbicide). Another important aspect of the study was to give direct feedback to the LRAM program about the effectiveness of two different herbicide/surfactant combinations.

After re-evaluating all the data from 2009 to 2012, Vos determined the first herbicide/surfactant combination was effective short-term but did not control woody stems in subsequent years. The second herbicide/surfactant combination controlled shrub growth longer but additional management would be needed to control re-sprouting shrub growth that could restrict training.

Some species of shrubs appeared to be more resilient to the treatment, and not all species reacted equally to the treatment.

Vos suspected the extensive root systems of some species make it difficult for the treatment to penetrate the entire root system.

The calibrated amount of herbicide applied may kill only a portion of the root leaving an unknown amount of the root intact to re-sprout. However, re-sprouting shrubs may not be considered a restriction to training depending on how many stems re-sprout.

Data showed a significant decrease in woody stem frequencies after treatment using the right herbicide/surfactant combination.

The experience with the vegetation community among firing points showed an occasional shrub is a positive contribution to the overall plant community because it offers diversity and cover in the landscape for training. In some situations, shrub cover can protect the soil and vegetation from heavy vehicle traffic.

The efforts of the RTLA and LRAM crews have contributed to ensuring the firing points at Fort McCoy remain viable training venues for helicopter landing operations and other vehicle-based training for the U.S. Armed Forces.

(Submitted by the Directorate of Plans, Training, Mobilization and Security Range Training Lands Assessment Coordinator.)