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Invasive Plants:  Impact on Biodiversity

Life in the City can be difficult for native plants and animals. Our local biodiversity crisis consists of pollution, habitat loss, fragmentation and neglect, all of which severely impact local habitats for native wildlife and plants

The number one destructive force on our local biodiversity is invasive species.

Invasive species are those that are introduced to an area they did not previously inhabit, where they exploit available ecological opportunities to spread rapidly and dominate. Some species were brought to San Francisco deliberately, such as South African iceplant to control erosion and Australian eucalyptus for lumber and windbreaks. Other “stowaways,” such as the European species of rat, came over in ships' holds. Of the thousands of introduced species, only some are invasive and destructive to San Francisco's natural heritage. These species take hold, spread rapidly, and if left unchecked, can displace our indigenous plants and animals.


The pesky subset of non-native plants known as invasive weeds are successful because they reproduce rapidly, are adapted to heavy disturbance, and find similar climatic conditions as in their home territories. When they arrive here, they do not come with their predators and pests to keep them in dynamic ecological balance.

Community stewardship is the only way to manage invasive weeds in the city sustainably.


For more information about invasive plants and a list of priority weeds, visit:
San Francisco Weed Management Area (SFWMA) 

California Invasive Plant Council (Cal-IPC)

Take a Tour of the San Francisco Six with the new SFWMA brochure


Go to the Edgehill Mountain website to learn about the Bradley Method of invasive weed control.

In this Section

Local Ecology

Rare Habitats

Gardening for Wildlife

Wildlife Links

Biodiversity Crisis

Invasive Weeds


Natural Areas

Green Hairstreak


Mt. Sutro



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