Natural Areas FAQs

How much of the city’s lands are in natural areas?

Of the 3,500 acres and 230 parks in San Francisco managed by the Recreation and Parks Department, natural areas comprise more than 1,100 acres in 32 parks or portions of parks.

What are some examples of natural areas?

Most of the undeveloped portions of Twin Peaks, Lake Merced, and Glen Canyon Park are designated natural areas. Natural areas do not contain manicured lawns, ball fields, or ornamental flowerbeds. Most of Golden Gate Park–approximately 96 percent–is not a natural area.

Why preserve nature in the middle of a big city?

People of all ages find refuge in these urban oases. Natural areas give the people of San Francisco a sense of place and distinguish it from anywhere else on earth. Preserving San Francisco’s historic natural features is as important as preserving its cultural legacy. Urban natural areas also provide rewarding educational and volunteer opportunities. Through the Recreation and Parks Department’s Youth Stewardship Program, urban schoolchildren have an opportunity to experience and learn about the nature that exists in their own backyards and neighborhoods; our volunteer program gives adults and youth alike an opportunity to help restore and become stewards of our rich natural heritage.

What is the Natural Areas Program and what does the Program do?

In the mid 1990s, in response to citizen concerns about the loss of natural resources, RPD developed the Natural Areas Program to protect and manage these Natural Areas for the natural and human values they provide. The mission of the Program is to restore and enhance the 32 natural areas totaling over 1,000 acres ranging in size from less than an acre to almost 400 acres, and develop and support community-based stewardship of the sites.

Natural Areas are remnants of San Francisco’s historic landscape and contain the City’s natural heritage. These areas support an array of native habitats and species, some found nowhere else in the world, such as the San Francisco Garter Snake and the Mission Blue Butterfly. The opportunity exists in these areas to protect and restore sensitive species and natural habitats for future generations.

Our natural areas contain irreplaceable biological communities and account for approximately one quarter of the City’s open space system. Historically, one would encounter an extraordinary variety of habitats and wildlife throughout San Francisco. Many of the insects, birds, and other animal species that depend on the diversity of native plants for food, shelter, and reproduction decline rapidly or even become extinct. Working alongside community stewards and volunteers, the Natural Areas Program protects our remaining wild lands by controlling the spread of invasive plants.

What is Significant Natural Resource Areas Management Plan (SNRAMP)?

The Management Plan is intended to guide the city’s natural resource protection, habitat restoration, trail and access improvements, other capital projects, and maintenance over the next 20 years. The Plan contains detailed information about the wildlife and plant habitats, species diversity, and recreational amenities in our 32 Natural Areas. The Plan will utilize this Information to recommend site-specific management actions. Implementation of the SNRAMP will achieve the following:

  • help prevent the local extinction of plants and animals
  • improve habitat for wildlife
  • increase safety
  • promote and protect biodiversity
  • improve access and recreational use in Natural Areas

What will SNRAMP do for San Francisco’s natural resources?

In order to protect natural resources while providing recreational opportunities, RPD developed SNRAMP to guide how we steward these lands. The development of the plan has been a 10 year process that consisted of numerous meeting with over 3,000 stakeholders, environmentalists, policy makers, and park users. The Plan is a cutting-edge and innovative way to maximize our resources while minimizing impact.

What is the City’s plan on overall forestry preservation?

The 20-year management plan applies to only around 5% of all of the trees in the San Francisco park system. Currently, roughly 18,000 invasive and non-native trees are proposed for removal out of the total estimated 118,000 trees within the Natural Areas System. Of these, approximately 54,000 are at Sharp Park, leaving 64,000 in San Francisco. Total removals within the City are estimated at around 3,400 or approximately only 5% of trees in urban forests of the Natural Areas System.

While some impact to fauna may occur during and immediately after invasive tree removal, the long-term and gradual conversion of the urban forests to native grassland and coastal scrub or oak woodland will benefit wildlife. Although animals do use the eucalyptus and forests, these areas are relatively poor quality wildlife habitat. These forest understories are either very open, a result of the eucalyptus oils suppressing plant growth, or they are dominated by ivy that climbs the trees and eventually kills them. Neither of these habitats are very productive wildlife habitat. Overall, forest management within the Natural Areas of San Francisco is estimated to result in the removal of approximately 5 percent of the forest. At no one location will all the trees, or for that matter, more than 15 percent of the existing trees be removed from Natural Areas within the City.This means that there will be abundant forest left for those species that prefer to use this habitat.

Does habitat restoration involve removing and planting trees?

As part of its mission to preserve habitat for birds and other animals, NAP plants trees and manages forests. Both native and exotic trees grow and are maintained within natural areas, because of the habitat and aesthetic values they provide. Native trees like the coast live oak and the arroyo willow not only provide superior food and habitat for wildlife, but also can coexist with other native plant communities. By contrast, a few non-indigenous tree species are invasive and can be problematic under some circumstances.

Tasmanian blue gum (or blue gum eucalyptus), for example, has few natural predators, rapid growth rates, and shades and poisons nearby sun-loving natives by exuding natural herbicides. NAP does selectively thin stands of small eucalyptus that are spreading into native plant communities, to allow sunlight to reach other plants and to improve the health of the entire ecosystem. NAP does not clear-cut trees, nor remove entire groves of mature trees, although it has removed some mature trees that threatened the growth of our native coast live oak trees, creek side willow, grasslands, or shrub communities.

What about forestry preservation in Mt. Davidson?

In the case of Mt. Davidson the SNRAMP outlines the Departments stewardship goals during a 20 year process of the total 39.9 acres of natural park land. Of this, 30.1 acres are “urban forest,” a term used to describe the eucalyptus dominated forest. Tree removal and thinning for habitat preservation and effective opening of the understory would occur only within 9 acres or approximately 30% of the 30.1 acres urban forest. Application of thinning management results in an increase in the average diameter of the residual trees, promotes the growth of those trees, and improves forest health through the removal of suppressed trees. More importantly, thinning will allow promotion and establishment of a native understory and diversity. In addition, thinning will also decrease the site dominance of invasive tree species, improving the overall health of the forest by relieving overcrowding and promoting habitat for a large array of wildlife.

No tree removal for habitat preservation would occur in the remaining 21.1 acres of urban forest. As a result, 70% of the urban forest at Mt Davidson would remain as is. The Management plan currently recommends that 1,600 or 15% out of the total 11,000 invasive trees at Mt Davidson. The amount of thinning that would occur in the 9 acre “restoration zones” would vary between 23% and 82%.

The number of trees affected includes sapling size trees over 15 feet tall. For example this could be a eucalyptus with a 2 inch diameter trunk. In the short term tree removals at Mt. Davidson are expected to occur gradually over 20 years and some opening of the canopy at selected areas may be visible from nearby vantage points. In the long term, most of Mt. Davidson will still support a lush and healthy urban forest even when tree removals are complete. Although the Plan proposes the removal of trees at Mt. Davidson and other locations in San Francisco, all these trees that are removed would be replaced on a 1:1 ratio with a more diverse mix of species that overall provide greater value to wildlife.

Is there poison oak in natural areas? What does NAP do about it?

Poison oak is very common in San Francisco natural areas. NAP continuously controls poison oak along trails in order to allow safe pedestrian access. To ensure that your visits to San Francisco’s natural areas are safe and pleasant, it’s a good idea to familiarize yourself with the plant’s appearance. Poison oak oils can also be transmitted to humans via dog hair, so be sure to keep your dog on leash and on trail.

What are invasive species?

Throughout history, humans have moved plants and animals around the globe, out of the environments they evolved in. Some species have been introduced intentionally, like ice plant to stabilize soils; others, like the Norwegian rat, were brought here unintentionally. A small proportion of theses introduced plants and animals have the capability to spread and become weeds in our natural areas. These species are capable of spreading rapidly and displacing native species, because they are adapted to similar climatic conditions, lack predators or pests, and have other characteristics that allow them to thrive. If left alone, our natural areas today would contain only a handful of native plants, and the animals that rely on a diversity of flora would go extinct.

What is the City’s plan to improve access to trails and natural areas?

Many of the trails that are proposed for removal are not officially designated by RPD. These social trails have developed by park users not using the official trail system. Social trails, redundant trails, and unsafe trails are not maintained by RPD result in soil loss and increased erosion and are detrimental to the sensitive plant species and wildlife throughout the natural habitat areas. To balance out some of the losses and to improve access to trails and recreation in natural areas, the SNRAMP includes both trail improvement projects to existing trails and creation of additional official trails.

As part of the 2008 Clean and Safe Neighborhood Parks Bond, RPD is planning to renovate trails in 11 natural areas including in Glen Canyon, Mt. Davidson, and other popular recreational areas. At Glen Canyon and Twin Peaks, new trails will be installed linking the two parks and neighborhoods, as part of the Creeks to Peaks Trail. This project will include the creation of new trails as well as renovation and improvements to existing trails. At Twin Peaks RPD is working on reclaiming a portion of the roadway to develop a new multiuse trail around the top that will afford great views and will significantly enhance the recreational opportunities in this park. At Corona Heights and Interior Greenbelt new trails were recently constructed. These new trails will allow access to areas that were not accessible before.

What is the City’s Integrated Pest Management Program for natural areas?

Integrated Pest Management (IPM) requires an integrated approach to all pest control operations; establishing regular monitoring, accountability requirements and phased out use of the most hazardous pesticides. RPD is in constant communication with the Department of the Environment’s IPM program to reduce the use of pesticides when possible. RPD participates in the Department of Environment’s IPM Technical Advisory Committee, which is populated by staff who are committed to reducing pesticide use. The Natural Areas Program (NAP) uses herbicides in our parks as a last resort to combat invasive weeds, the single biggest threat to San Francisco’s natural heritage. NAP is an active participant in the city’s award winning Integrated Pest Management Program (IPM).

SNRAMP EIR evaluated the health impacts associated with pesticide use and they were determined to be less than significant. Over the last 12 years, the Natural Areas Program has tried various treatments from hand weeding to herbicide application to control a handful of invasive but found that hand removal does not always fully and effectively remove aggressive invasive species. That being said, the majority of our weed removal is done through other means by utilizing volunteers, hand removal and / or mechanical options.

We understand that some visitors, kids, and dogs might come in direct contact with the weed, so we have established protocols to keep potential exposure at a minimum. In addition to limiting the areas impacted by the spraying and herbicide, it is one of our top priorities to continuously investigate alternative products that are effective, but do not impact rare plants. Why do humans need to be involved in preserving our natural areas? Doesn’t nature take care of itself?

At this point in our history, the balance has been tipped by humans and natural areas cannot take care of themselves. Because our natural landscape has been so altered by its human inhabitants, we need the help of people to preserve what is left. Just as humans are responsible for introducing invasive species, some believe we are obliged to act as stewards of our remaining natural heritage and help reverse the negative effects of invasive species. NAP, in conjunction with other land managers such as the Golden Gate National Recreation Area and the Port of San Francisco, encourages such stewardship.

How can I help preserve and protect natural areas?

As a visitor to a natural area you can help preserve these precious remnants by picking up trash and dog litter, minimizing soil disturbance and digging, respecting park rules and trail restrictions, and not picking or planting flowers or trees or disturbing wildlife. You can also volunteer to help restore native habitat and build and maintain trails within the natural areas. The Recreation and Parks Department has numerous ongoing and one-time volunteer opportunities.

How can I experience natural areas?

Natural areas are available to be explored by all, and the Recreation and Parks Department encourages you to visit them. Many San Franciscans hike, jog, fish, and bird watch in natural areas. You will find more than 30 miles of trails, with varying levels of difficulty, winding through a wide variety of habitats. In some areas where the plants, animals, or soils are fragile–for example, in newly planted areas–access may be limited.

Can I bring my dog to natural areas?

Dogs are welcome on leash in natural areas. Some dog behaviors, such as digging and chasing wildlife, can be damaging to natural areas, so it is important that dog owners be responsible for their pets’ activities. Please abide by posted park rules, clean up after your pet, prevent digging and wildlife disturbance, and stay in designated areas. Some parks and open spaces within the Recreation and Parks Department system have designated off-leash dog play areas.