Monitoring the Beautiful North Coast Semaphore Grass

March 27, 2023

To better understand the effectiveness of our habitat management that includes grazing and invasive species management in support of protecting threatened North coast semaphore grass populations, the MCRCD added an additional early-spring round of semaphore grass monitoring in some select areas on the project.

North coast semaphore grass, Pleuropogon hooverianus, is a tall perennial native bunchgrass which is listed as threatened in California. It is only found in three Northern California counties – Marin, Sonoma, and Mendocino. It generally flowers from late April to early June and can grow to 3 feet tall with pendulous flower heads.

The Monitoring and Management Plan for the Willits Bypass Mitigation Lands stipulates that one of the goals for MCRCD as land manager is to protect and enhance the populations of North coast semaphore grass on the project. Cattle grazing and mowing are some of the tools that help us achieve this goal. These activities keep the biomass of competing grasses down and allow enough sunlight to reach the semaphore grass as it grows. Another method that we use to enhance the North coast semaphore grass population is seed collection and seeding. Our seed collection permit with CDFW allows us to collect seed from existing semaphore grass stands and plant it in suitable habitats to supplement and expand current semaphore grass populations. A small percentage of semaphore grass seed is collected in the summer before the plant senesces and then later planted in the fall after a couple of rains have moistened the ground. To better ensure that the management methods being employed are successful, monitoring is done on the populations of this elegant species.

North coast semaphore grass monitoring occurs every year during the spring along established transects. Using transects allows us to compare the presence/absence, density, and health of the semaphore grass in the same location from year to year. This body of data informs us of any declines or increases in the semaphore grass populations. It was exciting to get out and look at the North coast semaphore grass early this spring and observe new growth and seedlings. More monitoring is planned for May and June so it will be interesting to see how the spring heat, grazing, and competition from other grasses affect the semaphore grass over the course of a few months. Weather and drought are of course factors that influence the success of North coast semaphore grass, but it is a resilient plant. This grass is a rhizomatous perennial that can put up leaves and get some early growth before the competition from other native and non-native grasses and the heat of early summer hits.

We were encouraged this year to see how many of the seedlings are successful and how robust most of the plants looked.