Biodiversity is a very large subject that is well worth everyone's time and attention. Today's column provides a brief overview of the topic and then focuses on home gardening.
Before we dig into this topic, review today's plant gallery, which relates to our transition to California native plants.
Biodiversity has been defined broadly as the variability of life on Earth. More specifically, it refers to species diversity and species richness. It is a natural occurrence among all living organisms, and varies with climate regions, geologic elevations and marine and terrestrial environments.
Biodiversity loss happens when plant or animal species disappear completely from Earth (extinction) or decrease or disappear in a specific area. Over the ages, natural events have led to large and sudden drops in biodiversity.
Human activities have led to an ongoing biodiversity loss. Human activities include habitat destruction, such as farming, deforestation and other forms of monoculture. Other human activities also contribute to the loss of diversity: air and water pollution (including nutrient pollution), overexploitation, collecting medicinal plants, introducing non-native invasive species and climate change.
Biodiversity with garden plants
While developing a residential landscape, homeowners often prioritize monoculture (lawns), and gardeners appreciate a wide variety of exotic plants (invasives). These practices may drive local native species to extinction by competing effectively, displacing preferred environments or hybridizing with related native species.
Ecologist Doug Tallamy has noted that "we have replaced the native plants necessary to fuel food webs with non-native ornamentals valued only for their aesthetics."
Lawns and alien invasions can cause extensive changes in the garden's structure, composition and global distribution of the animal and plant life of a particular region or habitat. This leads to the homogenization of a garden's fauna and flora, and the loss of biodiversity.
The response to this problem includes design policies, guided by science, to encourage the use of native plants in our gardens and communities.
California gardeners can pursue this constructive, ecological design by visiting public gardens featuring California native plants.
Visit native plant gardens
The California Native Plant Society's quarterly magazine, Flora, recommends 10 public gardens that showcase California native plants. This section provides edited versions of Flora's descriptions of six public gardens nearest to the Monterey Bay area. Public gardens generally require an admission price to support operations.
John Muir National Historic Site Garden (north of Concord ). Naturalist John Muir, typically associated with Yosemite National Park, also managed a large fruit orchard. The CNPS East Bay Chapter transformed Muir's home property into an "all-California native garden." For info, browse nps.gov/jomu.
Pacific Grove Museum of Natural History. This is one of California's oldest and most well-established destinations to explore the state's native flora. The garden features three spaces that reflect the area's important local ecosystems: coastal scrub, chaparral and oak woodland. Browse pgmuseum.org for more.
Santa Barbara Botanic Garden (Santa Barbara). This 76-acre classic is the quintessence of a community-based, biodiversity showcase. The garden offers more than 6 miles of paths through habitats featuring 1,000 species of California native plants from over 11 different dedicated ecosystems. The garden will celebrate its 100th anniversary in 2026. For info and required reservations, visit sbbotanicgarden.org.
Santa Ynez Chumash Museum and Cultural Center (north of Santa Barbara). This 3.5-acre garden opened in May, featuring 11,000 plants in 100 native plant species with traditional uses to the locally historic band of Chumash people. This small but inspirational native garden space broadens one's understanding and appreciation of native plants as agents of significant cultural heritage and a life-sustaining force for local indigenous Chumash people. Browse sychumashmuseum.org.
Tilden Regional Parks Botanic Garden (Berkeley). This 10-acre park, a majestic setting in the Berkeley Hills, celebrated its 75th anniversary this year. Its plants represent 10 regions of California. Its western flank -- the "Canyon Section" -- comprises most of the garden's regional native plant species. For more information, visit nativeplants.org.
Tule River Parkway (north of Bakersfield). Located in the Central Valley town of Porterville, this park offers 32 discrete planting spaces organized by theme. The spaces have been "adopted" by local sponsors and tended by CNPS volunteers. Browse tuleriverparkwayassociation.org.
In addition to Flora magazine's recommendations, at least two other public gardens include native plant sections well worth visiting.
UC Berkeley Botanical Garden (Berkeley). This garden is home to one of the largest species collections of California native plants in the world, including more than 200 plants on the California Native Plant Society's list of rare and endangered species. About a third of California's native plants are endemic to California, meaning that they can only be found in the state. Visit botanicalgarden.berkeley.edu/collections/california for information on the California collection.
UC Santa Cruz Arboretum and Botanic Garden (Santa Cruz). The California collection includes many native plants naturally occurring on the site. Most noteworthy are the ponderosa pines, probably the most maritime and at the lowest elevation of the entire North American range of the species. In addition, coast redwoods, Douglas firs, coast live oaks, California bays, willows, cottonwoods, madrones and buckeyes are there, along with rolling meadows of native bunchgrasses. For information on the California collection, visit arboretum.ucsc.edu/about/garden-collections/california-gardens.
Advance your gardening knowledge
To dig deeper into today's topic, search Wikipedia for "biodiversity," "biodiversity loss" and "effects of climate change on plant diversity."
To focus on biodiversity in the garden, read entomologist Doug Tallamy's brief article, "We Know Enough to Act," which is included in the current issue of the CNPS's magazine, Flora, and available online at tinyurl.com/5evzenwy.
Search the CNPS's website resources, which "imagine a California in which water-thirsty lawns are replaced by life-giving native plants, creating a thriving, connected network of natural habitat and California beauty."