Grown In Marin 

Our pastures and grasslands are complex and dynamic living systems with a long and changing history. Today's ranchers and grazers have inherited from Native Americans a 12,000 year old tradition of managing these ecosystems. Ranchers work as a team with cows and sheep to maintain the grasslands that make up 60% of our open space, one of our most important cultural and natural resources.

       If you walk through pasture in the Tomales or Point Reyes Peninsula area you find dozens of grass and forb species, including a surprising number of natives. You may also find some of our most noxious invasive species, like yellow star-thistle (Centaurea solstitialis) and wooly distaff thistle (Carthamus lanatus). These species mean trouble, any way you look at it. "Stickers" are a curse and catastrophe on the ranch, and trying to control them is one of the main expenses incurred by livestock operators, whose livelihood depends on balanced ecosystem management. Generations of our ranching neighbors have fought the thistle, with intermittent wins and regular losses. Seeing productive pastures invaded and ruined by thistle infestation is, indeed, a sad sight. How did we get here?

       The arrival of Spanish-style cattle management dramatically changed California's grasslands, starting with the introduction of European plants in the 1500s. These species migrated northward from Mexico and southern California; the invasion was well under way by the time Europeans reached Marin County. Our pastures today are a mix of native grasses and forbs and a host of European and Asian invaders. Many, like Italian ryegrass and soft chess, are permanently naturalized and have become mainstays for livestock forage, prized in pasture mixes. But others are perpetual pariahs, costly in loss of pasture and expensive to manage. The usual suspects are thistles: yellow and purple star-thistle (C. calcitrapa), wooly distaff, and Italian (Carduus pycnocephalus) and milk thistles (Silybum marianum).

        When a new invasive species arrives, often the conditions are ripe for a takeover. Thistles are opportunists with disturbance and fertility providing the opening. Often seeds are transported unknowingly through hay, in grading and filling materials, on farm machinery and by importing livestock. Just a few seeds can get the infestation started, and pasture managers need to be diligent and wary to catch thistles and eradicate them while there is still a chance.

       Wooly distaff thistle is the Tyrannosaurus Rex of Marin County invasives. It is an annual that forms tough, spiky stalks, which can remain standing for up to a year. These stands out-compete other species and quickly acquire dominance. Cattle refuse to enter the patches because the spiny foliage and flower heads can injure their eyes and mouths; soon the distaff is the dominant species. Each plant produces hundreds of seeds that remain viable for up to eight years or more, and germinate accordingly. This Mediterranean native is highly competitive with cereal crops and desirable rangeland species, and dense populations can develop. Distaff thistles are closely related to commercial safflower (Carthamus tinctorius), which precludes the development and release of biocontrol agents in California. If you have a bad infestation, you need to be attentive and diligent for at least eight years to eradicate the beast!       

       "Distaff is an aggressive thistle, which not only destroys good forage land, but wipes out delicate native plants as well," says rancher Sally Gale of Chileno Valley, "We stand to lose many acres of valuable pasture and open space. This isn't just another cute and quirky West Marin story; it's a serious problem."

       Marin has a history of implementing creative solutions to threats to our agriculture and open space. Collaborative work is a legacy here. We have waded through thorny and divisive issues before and come up with sensible and progressive answers.  In the '70s we met the development threat with zoning ordinances and the creation of the Marin Agricultural Land Trust. The Tomales Bay Agricultural Group partnered with UC Watershed Advisor Dave Lewis to monitor water quality on ranches, develop enhancements, and provide cleaner water for Tomales Bay.        

       Invasive species threats are not different. This, as Sally Gale says, is a serious problem; a very complicated problem, involving natural ecological forces, which we have yet to fully understand; complex socioeconomic issues, and environmental concerns. We all benefit from well-managed working landscapes and the responsible stewardship of our lush open spaces. Threats to our green "backyard" need to be met with educated analysis, understanding and the will to compromise and make difficult choices. We need to focus our collective attention on the problem and find ways to meet these problems head on. There is no right or wrong with this issue, only the long, complicated path to a solution.