Native Americans had no domesticated animals when Europeans arrived in the late 15th century. When Europeans brought cattle and sheep to the New World, they brought the Mediterranean grasses that fed their herds with them, often unintentionally. These non-native grasses spread quickly.
By the time Europeans arrived in California in the late 18th century, several European plants had spread from Mexico where Mediterranean grasses already dominated. In the mid-19th century, an influx of gold miners increased demand for beef. Grazing of the native bunch grasses created an opportunity for the non-native annual grasses to occupy the disturbed ground.(1) California’s native bunch grasses are not adapted to heavy grazing by herds of domesticated animals. The grassland of California is now about 98% non-native.(2)
Restoring California’s Grasslands
Because so much of California was grassland when Europeans arrived, the restoration of grassland is a high priority for native plant advocates. This is the story of one attempt to restore native grassland in the Sacramento Valley. The project was funded by UC Davis and Caltrans, the State of California’s transportation department.
- February 2003: 2-acres drill-seeded with native grasses
- June 2003: First-year planting declared a failure. Site was sprayed in May.
- October 2003: Site is burned and re-seeded.
- January 2004: Exotic grasses have been managed
- Bare soil and seedlings of broadleaf weeds remain
- May 2004:` About 1,000 plants of native grass remain
- August 2004: Yellow star thistle is mowed
- Nov 2005: A total of only four native grass plants appear to have survived
- Spring 2006: Plot is plowed and replanted by drill-seeding
- Sept 2006: 4% native grass underneath non-native weed canopy
- August 2008: Yellow star thistle and wild oats are invading from the edges.
- Native grasses expected to persist from 2 to 10 years depending on rainfall
- Autumn 2009: Fifth planting attempt produced only about 30% coverage
- August 2011: Natives and non-natives about 50/50
- January 2012: 27% natives and 72% non-natives
Failure at what cost?
After many years of replanting, reseeding, mowing, burning, plowing, and spraying, the 2-acre site is still dominated by non-native species and those natives which survived are not expected to persist for more than 10 years as they are overtaken by the non-natives. Using state-of-the-art-techniques and the expertise of one of the most prestigious agricultural research institutions in the world, this project must be considered a failure. The price of this failed effort was $225,000 per acre.
[Edited to Add: We discovered two new sources of information (3) on this topic after publishing this article. These sources inform us that the cost estimate in our original source is based on a research grant which probably included costs associated with the research, such as data gathering and analysis. Therefore, the price of this effort overestimates the cost of the restoration itself. Although the new sources of information provide cost estimates of grassland restoration, we don’t consider those estimates substantially more accurate because they report only the direct cost of the project and predict a shorter time frame for the restoration than the actual project which took 5 years.]
They did the best they knew how to do. They were only trying to restore 2-acres. They spent nearly $500,000. And what do they have to show for it? A few native plants that will disappear in 10 years or less.
[Edited to Add: The new sources of information also reach different conclusions with respect to the success of these restorations. Although the specific test plot described in our original source is not included in the study, many similar projects are considered successful by the new source of information. This seems to be a question of “glass-half-empty” vs “glass-half-full.” The reported results are similar in both publications, i.e., non-natives persist in all test plots and natives are not expected to persist beyond 10 years.
However, the positive evaluation is based on a claim that the maintenance of non-native grasses is more costly than these restoration efforts. We find that hard to believe. For example, we don’t see any reason to spray herbicides on non-natives being maintained in a highway verge which is the standard treatment for the restoration of natives. We know that the cost of each application of herbicides on much smaller plots of land in the natural areas in San Francisco was $9,000 per application in 2010. We therefore doubt that it costs more to maintain non-native grassland than it does to restore native grasses in their place.]
San Franciscans who have been watching the so-called “natural areas” in San Francisco for 15 years should not be surprised or disappointed by these weed-infested plots behind fences. Why should the Natural Areas Program be more successful than the scientists at UC Davis? Given that NAP is working on tiny plots of urban land–which add up to 1,100 acres–that are completely surrounded by exotic plants, shouldn’t we expect even less success than what UC Davis could accomplish in the Sacramento Valley surrounded by acres of open space? Lower your expectations, San Francisco. Or refuse to waste your tax dollars on plowing the sea.
(1) Crosby, Alfred, Ecological Imperialism, Cambridge University Press, 2009, page 152-154
(2) Schoenherr, Allan, A Natural History of California, UC Press, 1992