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Thursday, February 19, 2015

Weed wars- Part 1

Here at the Conservancy we have been celebrating a small but ringing achievement, and we thought we would share with you the good news… In year 1 of our stewardship program, we have eradicated a very bad, very scary weed from the Ranch. Any of you who have spent time in creek areas along our southern California coastline will be familiar with this ecosystem monster and how it can transform a once biologically diverse and healthy riparian area into a grassy nightmare:
Arundo donax (shiver). 

Arundo donax on Tejon Ranch.
For those of you who aren’t as familiar with arundo, you may be confused about why we would demonize this species and relish its removal from the Ranch. Arundo donax, or giant reed, is a perennial grass from Asia. It was reportedly brought here both historically by Spanish settlers for building and livestock food materials, as well as in modern times as a fast-growing ornamental for landscaping. And fast growing it is, reaching up to 30 feet tall and growing at a rate of up to 2 inches every day, thus overtaking and outcompeting native plant communities and drastically altering habitat for animal species. This rapid growth is estimated to cost almost 530 gallons of water for every 1 meter of standing biomass. So not only does it grow and spread incredibly fast, it is an extreme water consumer which in these dry times creates even more of an undue burden on the scant water available for both wild and anthropogenic systems. If this wasn’t enough, scientists and land managers have attributed a long and nasty laundry list of extreme ecological transformations attributed to arundo dominated areas, including drastically changing the hydrology of creek systems resulting in degradation of biodiversity and significantly increasing fire frequency and severity. In the California Invasive Plant Council (Cal-IPC) Arundo Distribution and Impact Report from 2011, they estimated that arundo inhabited over 8,900 acres of coastal watersheds between Monterey and San Diego, with a ‘typical’ stand measuring over 80% cover. Although there are active treatment campaigns throughout California, the rapid growth and dispersal of this species causes grave concern among scientists and land managers and has prompted Cal-IPC in their 2006 California Invasive Plant Inventory as rating it with a high listing at the state level--severely impactful, moderately invasive, and severely distributed.
Flowering arundo perched on the banks of Tejon Creek.
Scary, right? Here on Tejon Ranch we had two known stands of arundo in the Old Headquarters conservation easement on the San Joaquin Valley side of the property—one adjacent to agricultural operations and another perched on the bank above Tejon Creek beside a historic site. Working collaboratively with both the Tejon Ranch Company and the Los Angeles Conservation Corps, we used both mechanical and manual methods to remove the above ground biomass, and we have been closely monitoring these areas for regrowth. Although our arundo patches were both very small (totaling about half of an acre between them), we were thrilled to remove the unnecessary risk they posed to spreading and degrading our diverse systems here on the Ranch. Many thanks to the Tejon Ranch Company and the Los Angeles Conservation Corps for supporting this important work!

LACC workers manually removing arundo from Tejon Creek.  

Bell, G. 1993. Biology and Growth Habits of Giant Reed (Arundo donax). Arundo donax Workshop Proceedings, Ontario, CA.

Giessow, J., J. Casanova, R. Leclerc, G. Fleming, and J. Giessow. 2011. Arundo donax (giant reed): Distribution and impact report. Prepared for the State Water Resources Control Board by the California Invasive Plant Council. Agreement No. 06-374-559-0.

Cal-IPC. 2006. California Invasive Plant Inventory. Cal-IPC Publication 2006-02. California Invasive Plant Council: Berkeley, CA.

Katagi, W., C. Loper, and N. Jackson. 2002. Southern California Integrated Watershed Program: Arundo Removal Protocol.