News.bytes Extra, issue 389

Clear Creek noxious weeds attacked with fire

Approximately 30 acres of California annual grassland was burned at the Clear Creek Management Area this spring as a control measure for two invasive weeds.

The Bureau of Land Management’s Hollister Field Office and Monterey 1 fire crews carried out the control burn on the grassland containing yellow starthistle and the equally noxious invasive annual grass medusahead, said Ryan O’Dell, natural resources specialist for botany/soil science in the Hollister Field Office. (text continues below)

The project was funded under the American Recovery and Reinvestment Act of 2009.

Yellow starthistle is a noxious invasive annual species found throughout California, particularly in grasslands.  Native to the Mediterranean region, yellow starthistle was first introduced to California in the 1850s.  It now dominates over 15 million acres in California alone.

“The species tends to form monoculture stands, reducing herbaceous plant community species diversity and presents a barrier to wild animal movement, owing to its signature yellow, spiny flower heads.  Yellow starthistle also prevents domesticated animal grazing within rangelands and is toxic to horses,” he said.

Control burns are an integral part of the Clear Creek Management Area noxious weed control program for yellow starthistle and medusahead. The 71-acre total project area is regarded as an invasion front for yellow starthistle.  When timed during the flowering interval for yellow starthistle (mid-June), control burns are highly effective at killing the plants and incinerating any seed they may have produced.  The control burns also reduce herbaceous mulch levels, reducing fine fuel loads and the fire hazard they present, as well as making it easier for workers to apply herbicide to any yellow starthistle plants that may return the following spring.

A combination of timed control burns, hand pulling, mowing, and herbicide (clopyralid and glyphosate) application has reduced the abundance of yellow starthistle within the project area by more than 90 percent since the project was initiated in 2005.  The project area is habitat for the BLM sensitive slender pentachaeta which is known only from the population at the Clear Creek Management Area and one other in the south Coast Range.
The project area is immediately adjacent to both occupied and potential habitat of the federally-listed threatened San Benito evening primrose. Noxious weed control within the project area affords protection of San Benito evening primrose habitat from invasion, he said.

One area, before...

...and after:

- Dave Christy, BLM California Central Region, 6/30/09

BLM-California News.bytes, issue 389