REW teams up with Mariposa Consulting for Ravenna grass removal in Grand Canyon
In October, we partnered with the National Parks Service and Mariposa Ecological and Botanical Consulting for a project involving the mapping and removal of Ravenna grass along the Colorado River in Grand Canyon National Park (GCNP).
The group, including 7 people and 4 boats, stopped at previously mapped infestations, searching these areas for regrowth from the roots or seeds of treated plants. The trip consisted of rafting 225 river miles, safely navigating over 80 big water rapids, and destroying invasive Ravenna grass from Lees Ferry to Diamond Creek over the course of 16 days.
Ravenna grass is an ornamental grass native to Southern Europe and continues to be sold and planted in gardens throughout the United States today. After being introduced at Lees Ferry in GCNP in the 1970s, it rapidly spread, and by 1990 was documented over 225 miles downstream. The National Park Service documented over 10,000 plants killed annually on their eradication trips in the 1990s but by 2014, plant counts stabilized at around 100. In 2022, the group removed 421 plants with a total of 543 seed heads. This total was up from 95 plants in 2021 and 337 plants in 2020, showing that searching for undiscovered infestations remains vital to the preservation of this delicate canyon environment.
This plant has proven to be especially difficult to eradicate due to the logistical complexity of traveling in GCNP and the identification and removal of the plant amongst very similar plant species. With sustained efforts, eradication of Ravenna grass in the Grand Canyon is possible.