Montara Prairie Renewal Project
Background
Picturing California's Native Grasslands
Imagine carpets of grasses and wildflowers spreading as far as the eye can see along California’s coastal hills and bluffs. This habitat, known as a coastal prairie, once covered a thousand square miles from Santa Barbara County to Oregon. Coastal prairies have the most species diversity of any grassland type in North America. Today, coastal prairies persist in small patches that have escaped development and agriculture. Perennial bunch grasses, such as California oatgrass, blue wildrye, and purple needlegrass are foundational species in California’s coastal grasslands. Purple needle grass is California’s most widespread native grass (and the official state grass!).
Native grasslands have diminished across California but are still a vital habitat for many species. They hold 40% of the state’s native plant species and 90% of its rare and endangered plants. Grasslands support flora and fauna that can't live in other habitats, making them globally important reservoirs of biodiversity. They also provide important benefits such as carbon storage and soil stabilization. However, grassland ecosystems are disappearing around the world. California’s native grasslands need our help to persist.
Invasive Species Impacting Grasslands
Although endemic to only a few parts of California, Monterey pines are the most widely planted tree species in the world. They can grow in many areas, including grasslands and shrublands due to their adaptable nature. Seedlings can be 1-2 ft tall after one growing season, and by age 5 trees average 20 ft in height. Planted trees in developed areas have allowed Monterey pines to start growing in prairie habitat, shifting native grasslands towards forest ecosystems.
This shift has displaced species native to Bay Area grasslands. An estimated 25 acres of grasslands in Montara Prairie have been lost to tree invasions over the past 25 years. In wetlands, Cape ivy is the main invasive species in Rancho. It is toxic to aquatic life and spreads rapidly, crowding out native wetland plants.
Montara Prairie
Montara Prairie is located within Rancho Corral de Tierra (Rancho) on coastal terraces and foothills at the base of Montara Mountain in San Mateo County. Rancho holds 4,000 acres of coastal views, a diversity of wildlife, and ecologically important watersheds, protecting a valued landscape in the Bay Area. In Montara Prairie you can find rare and endangered plants such as Hickman’s potentilla, artist’s popcornflower, supple daisy, and numerous other plants and animals found only on the California coast. This rich community provides habitat for many coastal creatures that depend on grasslands, such as the federally-listed threatened California red-legged frog, and species of concern such as northern harrier, white-tailed kite, and grasshopper sparrow. Montara Prairie is protected as part of the Golden Gate National Recreation Area, but we need to help stop the spread of invasive trees and shrubs that are threatening it.
Rancho's Land Use History
Rancho Corral de Tierra is within the ancestral homeland of the Chiguan band of the Ramaytush Ohlone, the original peoples of the San Francisco Peninsula. When Native Americans were the primary caretakers of the Bay Area, they used fire to preserve grasslands by burning encroaching shrubs and trees, a cultural practice of tribes across California. Wildlife, including elk and grizzly bears once thrived here, contributing to a pattern of disturbance that allowed California grasslands to thrive for thousands of years. Disturbance regimes in California’s grasslands have changed dramatically over the past 200 years, greatly impacting ecosystem dynamics.
Land use shifted to cattle and livestock ranching during the Spanish colonial period, when Mission Dolores grazed large herds of cattle on the San Mateo coast. Subsequently, Rancho Corral de Tierra, or “corral of earth”, was established in 1844 as one of many Mexican land grants in the Bay Area. Livestock were introduced during this period, including cattle, horses, and sheep, while hunting decimated wildlife populations. The use of fire as a way to manage and cultivate grasslands was suppressed, and the disturbance regime shifted from wildlife grazing to livestock grazing.
In the mid 1800s the California gold rush brought a huge influx of new immigrants and a major increase in the number of livestock in the Bay Area. Agriculture came to the San Francisco Peninsula in the late 1800s, and most coastal terraces were converted to crops by the mid 20th century. The map to the right was hand drawn in 1866 to map part of the San Francisco Peninsula in detail for the US Coast Survey. Grasslands changed most dramatically during this period of growth due impacts from agriculture, development, introduction of new plants and continued cultural suppression of fire as a land management practice. These trends continue today, with increasing urbanization, new incursions of invasive plants, and climate change posing the greatest threat to California’s coastal grasslands.
About the Project
Native grasslands and wetlands in Rancho benefit both the local ecosystem and community. Restoring native grassland habitat will only become more difficult over time as more acres are lost to plant invasions. Once grassland plant communities are converted to forest communities, it becomes much more difficult to restore native grass communities. This project will halt or reverse the ongoing loss of ecologically important coastal prairie and herbaceous wetland habitats supporting rare, endemic, and endangered plants at Rancho. Coastal prairies and wetlands contribute significantly to biodiversity in the Bay Area, which is a global biodiversity hotspot.
Where do you notice trees growing in 1941 vs. 2018?
1941
1983
2018
The photos above highlight how tree coverage has rapidly expanded over time. Historically, trees were not common in Rancho. Trees that are present were primarily introduced by people who planted trees near their houses as the areas surrounding Rancho became more developed.
How Trees Affect Rancho’s Grasslands
In the past 30 years over 30% percent of Rancho’s grasslands have been lost to woody plant invasions. If this trend continues, we may expect to lose most of the grasslands within the next sixty years. When grassland habitats are converted to forest communities, restoring native habitat becomes even more difficult because of changes in soil properties and a lack of native plants to populate the area. These shifts are difficult, if not infeasible to reverse.
Replanting native species is necessary to ensure the success of tree removal. Additionally, long-term monitoring and maintenance will allow for informed management decisions to preserve the grassland. This project will restore coastal prairie and freshwater marsh habitats, supporting threatened and endangered plants and animals in Rancho through the removal of invasive and encroaching plants and the planting of native species.
Sweeney Ridge: A Grassland Restoration Success Story
Before and after shrub removal (drag the arrow to see the full photo)
The Bunker Flats area of Sweeney Ridge is a historic grassland that hosts threatened and endangered species, notably the Mission blue butterfly. Similar to Montara Prairie, the grassland on Sweeney Ridge was encroached upon by shrubs and trees and much of the historic grassland habitat was disappearing. In 2019 the park started removing sections of trees and shrubs as part of a large-scale grassland restoration project. Since the initial tree and shrub removals, maintenance has involved continuing to plant more native grasses and remove invasive species, including invasive annual grasses. Shrubs have also continued to be removed intermittently to expand and protect historic grassland habitats. Monitoring has also been an integral part of the restoration efforts, especially for tracking the success of Mission blue butterfly recovery. Today many native wildflowers grow in the Bunker Flats grassland. The photos below show the success of restoration efforts with wildflowers flourishing in an area that was once shrubs.
Sweeney ridge during wildflower season
Timeline
2024 - 2026
Remove invasive trees, shrubs, and grasses from designated areas in prairies, and remove cape ivy in marshes.
2025 - 2026
Continue repopulating native species by planting seeds and container plants.
Post project completion
Monitor and maintain native plant populations.
Removal Areas
The maps below show tree and shrub removal areas in grasslands and cape ivy removal areas in wetlands. We will begin removing trees and shrubs in priority area 1, and we will continue in priority area 2 if funding is available.
Tree removals
Shrub removals
Cape ivy removal areas from wetlands.
All removal areas for the prairie renewal project
"Core grasslands" are areas that were free of invasive trees and shrubs less than forty years ago. This project aims to renew native coastal prairie in these areas
Imagery from 1983 shows healthy grasslands in the core grassland areas before tree and shrub invasion
How This Project Will Affect Park Visitors
There will be some trail closures in work areas, but these closures are temporary and other nearby trails will remain open. The use of chainsaws to remove the trees will also result in more noise than usual.
Post-Completion
Hickman's Potentilla (endangered)
Maintenance & Monitoring
When tree removal and initial replanting are complete, the project will move into the maintenance phase, which involves continued invasive plant control and revegetation. We will conduct regular vegetation surveys to monitor the success of our plantings and to keep track of invasive plants. Through vegetation monitoring we can understand how long it takes the plantings to establish, or if we need to adapt our management the health of the restored grassland.
Progress Photos
Below are photos of Montara Prairie before the restoration project.
August 2024
Get ready for wildflowers!
We are only able to accomplish large-scale restoration projects because of the planning, collaboration, and support of those involved. Years of research and preparation have gone into making this restoration project a reality. Thank you for taking time to read this Story Map, your support is valued. To learn about more about California grasslands and opportunities for engagement, please see the links below.
Acknowledgements
Many thanks to Eric Wrubel for your support in creating this StoryMap and for your work in planning this restoration project. Thank you to Elena Wolf and Laura Booth for helping me edit the content, Zac Stanley for your guidance in navigating GIS, and each person who took time to review this project. Big thank you to Environment for the Americas in partnership with the National Park Service for funding my internship.
