California’s coastal prairies are the most species-rich grassland types in North America

At first light on Cypress Grove Preserve, Jim Jensen starts his coffee then is out the door for the morning rounds managing a flock of sheep who have come to help us care for the land. The sheep are early risers, and they have already made good work of the coyote brush and tall grasses within their temporary enclosure. Jensen’s arrival signals a welcome move to what’s just out of reach and a few of the veterans start to bellow, watching his every move. He lays out a couple hundred feet of electric netting, carefully weaving around brush that could draw down the fence voltage, then with a few whistles and the swing of a post, the sheep race to the new plot, crunching through the brush and trampling the dense vegetation.   

Jensen, who is land steward of our Tomales Bay properties, has been looking for ways to bring back native grasslands along the eastern shore of the Bay. He believes the sheep, and ruminants in general, may promote more biodiversity. 

California’s coastal prairies are the most species-rich grassland types in North America. Over 250 species of wildflowers and grassland-dependent mammals, birds, insects, and reptiles rely on coastal prairie, yet less than 1% of historic native coastal grasslands remain.

Moving from “protected” to “disturbed” to save remaining coastal grasslands

“These grasslands evolved and are sustained by disturbance activities that prevent woody encroachment,” explains Jensen. “Historically, the disturbance included large herds of elk and deer that were moving up and down the coast with predators such as grizzly bears and mountain lions keeping them on the move. Below the soil surface, this “herd effect” stimulated deep rooted perennial grasses adapted to this climate. Coast Miwok were likely using fire to maintain open areas and to regenerate plant communities they relied upon.”  

While modern-day development and more intensive land management such as tillage chewed up a substantial amount of coastal open space, some areas set aside for “preservation” also contributed to the demise of grasslands as trees, shrubs and non-native vegetation moved in, blocking sunlight and nutrients for the native plants of the prairie. In this case, the paradigm that “nature should be left alone” slowly removed these disturbance regimes from protected lands like Cypress Grove Preserve. 

“It’s not the diverse site it would be if it had some occasional disturbance going through there from time to time,” Jensen adds. 

A multi-year case study

Jensen’s years of experience grazing sheep and cattle in West Marin led him to develop a multi-year case study for restoring an area of the preserve that converted from hayfields to coyote brush over the past 50 years.  

We also are testing the use of prescribed fire in another unit of grassland and brush and will compare results. 

“We think that grazing and prescribed fire may help us introduce a regular cycle of disturbance to grasslands, providing space and sunlight for long dormant native grasses, wildflowers, and other plants,” Jensen offers. 

The herd spends 2-3 months on the preserve in the late summer-early fall. They are thinning coyote brush and reducing decades of potentially flammable thatch under power lines. Along with the much-needed disturbance, they leave behind rich manure and open areas for wildlife. 

Throughout the trial, Jensen has worked with True Grass Farms, who provides local ecological grazing services. “It has been a win-win, giving the sheep a place to land after being on other grazing projects in the area,” he says. Fibershed, a Northern California nonprofit that supports locally based grazers and fiber producers, provided a grant for temporary fencing. Point Blue Conservation Science helped Jensen set up a system, known as a standard monitoring protocol, to track changes in the conditions of the land, primarily soil and plant conditions.   

Where the herd leads, wildlife and insights follow

“Much of this project is observation — change over time that maybe can’t be quantified in data but rather observed by people who are on the land often,” says Jensen. 

Jensen’s co-workers Scott Jennings and David Lumpkin, both avian ecologists, walk the preserve several times a week and have noticed an uptick in the number of sparrows using the grazed areas, finding an abundance of seeds in the exposed soil. “The quail are dusting themselves in the sheep beds and the cottontail rabbits are bounding along the road edge getting the tender re-sprouts,” Jensen adds.  
 
Hawks and owls perch above the newly opened fields, spotting prey more easily. Bobcats and coyotes on the hunt also have easier access to the prairie’s below-ground denizens, like California voles and pocket gophers. Deer prefer the grazed areas after the first fall rains germinate nutritious growth.  

An adaptive plan

Early results from this trial are helping Jensen and others compare managed disturbance events and develop future practices that are both realistic and effective. For example, switching the grazing timing to late spring may help to reduce bolting annual grasses and make room for later arriving native perennial grasses. 

By noon the flock has gathered in a shady spot, ruminating. That leaves Jensen time to reflect as well. 

“If we hadn’t acted, the coyote brush would continue to move toward a state of monoculture and the fuel loading would also continue to increase, year after year,” he says, adding that grazing this area with sheep has both environmental and economic benefits. “It would be much more destructive to mow this area with a tractor — and more expensive.”

Resources available for people interested in grazing for land stewardship

Prescribed grazing is a growing practice to manage fuel loading and promote biodiversity and can be a great alternative to the use of heavy equipment. Learn about your local community grazing cooperative, Resource Conservation District, or local park or utility district’s grazing program and how it can be a win for local communities and biodiversity. Ask questions, support local farmers, and good grazing stewardship.  

California is investing in grazing activities as well. Senate Bill 675, signed into law in 2024, expands the availability of local assistance grants to grazing-based fire fuels reduction and home hardening projects. 

Stewardship initiatives like this are made possible by Audubon Canyon Ranch members and supporters. Become a member and choose from several benefit levels here >