As part of remediation efforts at a former oil field, Trihydro helped reduce the presence of veldt grass, an invasive species, to create conditions where native vegetation could succeed. The project team used a combination of aerial and ground herbicide applications and performed routine ecological surveys to confirm habitat health. 

At a former oil field, remediation requirements included a sitewide exotic species eradication and management program. The Program set priorities for non-native plant control at the site and required reducing, and in some areas, eliminating veldt grass to improve conditions for native vegetation.

After initial Program goals were not met, aerial herbicide application was added as a method for treating large areas of veldt grass. Trihydro joined the project to support the aerial herbicide application program, treating several thousand acres over six years. The herbicide was deployed from a helicopter equipped with an onboard GPS navigation system and a 32-foot boom sprayer. To prevent aerial application in sensitive areas, buffer areas were included on the helicopter pilot’s GPS navigation system and marked in the field with high visibility flags atop 7-foot poles. Ground applications complemented aerial herbicide applications to provide greater control around sensitive areas such as wetlands, avian nests, and powerlines.

To assess for ecological impacts, Trihydro completed wildlife surveys before, during, and after aerial herbicide application. Before aerial spraying, Trihydro established a wildlife survey route within the proposed spray area that included multiple avian point count locations and nesting bird surveys. Mammal, reptile, and avian species expected within the habitat were consistently seen in spray areas after treatment. Further, avian behaviors such as foraging, preening, singing, perching, and nesting were consistent before, during, and after treatment. Trihydro also conducted botanical surveys in aerial spray application areas and control areas before and after treatment each year to document changes in the cover of veldt grass and any changes in vegetation composition.

Project site mapping demonstrates a year-over-year decrease in veldt grass volume. The aerial herbicide application program has proved efficient and effective at controlling veldt grass on a landscape level. Further, the efficiency of aerial application allows for a greater treatment area each year, which has accelerated the rate of reduction of veldt grass across the site. Reducing veldt grass field-wide supports the preservation of the native vegetation community and associated wildlife. Native plant recruitment within areas of veldt grass removal has been successfully documented.

Aerial herbicide application allows for a greater treatment area each year, which has accelerated the rate of reduction of veldt grass across the site.

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