Managing Invasive Plants with Fire

Wed, 09/12/2018 - 15:53 -- jeremiahbender

Controlled burns are used in California to imitate the natural role of fire in ecosystems, reduce hazardous buildups of dead plant material, and to propagate fire-dependent species. However, CCBER utilizes prescribed fires for a slightly different purpose; high-intensity controlled burns on Lagoon Island are used to remove a particularly abundant invasive grass, Ripgut brome (Bromus diandrus). Ripgut brome is one of the many European annual grass species that have displaced native vegetation throughout much of California. True to its name, the individual flowers have tiny, rough teeth that can injure livestock and pets. Ripgut brome inhibits the natural succession of coastal grassland to coastal sage scrub by forming tall, dense stands that prevent the growth of native species. Even if an area is fully weeded, new seedlings will simply sprout up from the dense seedbank.

              Large spikelets with needlelike awns are a distinguishing characteristic of Ripgut brome. 

CCBER’s inspiration for using high-intensity prescribed burns to manage Ripgut brome on Lagoon Island developed from an EEMB Masters project by student Alice Levine working in Professor Carla D’Antonio's lab. In 2006, much of the Lagoon Island Mesa was dominated by ripgut, and Alice began researching the feasibility of using fire as a control method. She hypothesized that the addition of dried Coyote brush (Baccharis pilularis) would create higher fire intensity, leading to greater depletion of the ripgut brome litter layer and seed bank. By conducting over 40 small experimental burns on Lagoon Island, Alice found that adding supplemental fuel significantly reduced the number of ripgut brome seedlings compared to only a slight reduction with burns using just existing fuel loads. She also investigated the most successful strategies for revegetating the burn areas with native coastal sage scrub species, and found that a combination of broadcast seeding and hand planting resulted in the greatest amount of native cover.

             CCBER Restoration Staff dispersing dried Coyote brush over this year's plot in preparation for the burn. 

Following Alice’s positive results and the persistence of the small 2 meter square plots of native plants within the matrix of ripgut brome, CBBER adopted the use of dried Coyote brush as supplemental fuel and included a mix of broadcast seeding and hand planting as revegetation strategies. By utilizing dried Coyote brush that has been removed from other management areas, CCBER minimizes the need for extra resources and helps reduce fire risk elsewhere. Although Coyote brush is a native coastal sage scrub species, it is controlled due to its tendency to form dense monotypic stands. In June 2009 and August 2011, CCBER conducted successful controlled burns on half-acre plots on Lagoon Island. To date there have been 6 burns on Lagoon Island. Following the 2014 and 2016 burn, lagoon visitors in the spring were treated to a colorful wildflower show as Redmaids (Calandrinia menziesii), California poppies (Eschscholzia californica) and other native wildflowers sprouted up.


                                  Red maids (Calandrinia menziesii) were especially plentiful in the spring wildflower bloom following the 2016 burn. 

This year’s burn site is located between the old burn plots and the original experimental plots, and was chosen because it was dominated by Ripgut brome and had a very low percentage of native plant cover. Similar to the other burn sites, it is about a half-acre in size and CCBER crews have been working the past few weeks to cover the area in a dense layer of dried Coyote brush. On August 31, CCBER conducted their sixth burn on Lagoon island with the help of the Santa Barbara County Fire Department. The fire was ignited using drip torches, and burned slowly across the half acre site for nearly two hours. Fire crews were on constant lookout along the periphery, and a mobile water tank with a power sprayer was present as well.


Don't worry, this area won't be bare for long! We're excited to see how the plot will change in the coming months, and you can find out too by following CCBER on Facebook and Instagram.  


Wednesday, September 12, 2018 - 14:45