Method: Development and Implementation of a Vegetation Management Plan

The History Leading to the Plan

In 1994, the National Park Service (NPS) published a general management plan amendment (GMPA) to guide management and define future uses of the Presidio. From the GMPA, NPS determined that a vegetation management plan with an environmental assessment was needed to address a number of concerns:

• The historic forest was in decline, with many trees approaching the end of their natural life span.

• Historic viewsheds had been blocked by mature trees, or cleared by "topping," creating deformed trees along the edges of the park.

• The natural areas, which contain some of San Francisco's last remaining native plant communities, were threatened by recreational use or the invasion of nonnative species.

• The horticultural landscape surrounding historic structures needed to be restored in a manner consistent with the Presidio's listing as a national historic landmark.

The intense public interest in management of the Presidio influenced the process for developing the vegetation management plan. Many who grew up in the area are concerned about changes in the appearance of the vegetation within the landscape or changes in recreational use. In consideration of this public interest and concern, NPS decided that the vegetation management plan would be carried out through the standard National Environmental Policy Act review process, allowing formal public comment.

A Process for Public Opinion and Expert Advice

In September 1997, to initiate the scoping phase of the planning process, a brochure with a list of issues and general guidelines was developed and mailed to 1,400 neighboring homeowners, tenants, representatives of agencies and organizations, and others. Public comments were received at two workshops and through returned brochures and letters. The more than one hundred responses generated, along with resource information and legal and policy requirements, were used to shape the management actions, alternatives, and issues addressed in the draft VMP. A public workshop on preliminary issues also contributed to the draft, which was released in July 1999. In addition to public review of the document, NPS and the Presidio Trust held a one-day charrette to solicit technical comments. This interdisciplinary group was composed of academic, public sector, and private sector specialists with backgrounds in landscape architecture, historic landscape preservation, forestry, urban forestry, resource management, horticulture, and conservation biology. The group examined the draft VMP for its integration of natural and cultural landscapes, opportunities for public access and recreational use, and implementation strategies and techniques.

In June 2000, in order to better facilitate the decision-making process, the National Park Service and the Presidio Trust issued a staff report that summarized public comments on the draft, identified and analyzed particular issues that had surfaced during the comment period, and clarified points made in the plan. The final plan was published in December 2001.

Plan Objectives

The vegetative management plan divides the Presidio into three zones that reflect what the predominant vegetative complex will be after implementation: the historic forest, native plant communities, and landscape vegetation. Central to the plan is the development of sustainable vegetation that can be managed with less maintenance effort than is currently required.

One objective of the plan is to restore and rehabilitate the historic forest within its original boundaries. Resource managers and planners used 1935 aerial photographs to delineate the boundaries of the historic forest. Their rationale was that the trees appearing in the 1935 photos were those able to survive in the local climate under the given conditions, and therefore determined the maximum extent of the historic forest planted under Major Jones's plan. As historic trees age and die, openings will be created within the forest and replacement trees will be planted. Over time, the historic forest will become more age- and species-diverse, but managers will ensure that the historic species continue to dominate. Several highly photographed signature stands within the forest will be preserved. Scenic vistas will be reopened and maintained, and Monterey cypress that have been "topped" will be replaced with lower-growing species.

Another objective of the plan is the restoration and expansion of native plant communities. Nonnative trees that have "escaped" from the historic forest into native plant communities will be removed to control their encroachment. Habitat for 12 species of rare or endangered plants will be protected and enhanced.

As a third objective, the historic plantings and landscape character will be maintained within the landscape vegetation zone. Replacement plant materials will be selected after consideration of the threats they may pose to native plants through invasive tendencies or hybridization.

Carrying Out the Plan

Revegetation

Revegetation in the Presidio presents its own challenges. Much of the soil is sandy and water is very limited. One site forester suggested that, by following a proposed VMP action and creating a diverse understory of native species in the forest, the competition for water would only be intensified. He has been successful in creating small, sunny openings of about one-third acre by removing several dead or dying mature trees. Neighbors have been opposed to creating openings larger than this. These openings can then be replanted with native plants if the plants are given sufficient irrigation. Although the public would prefer to replant with large, older trees, the forester will use one- to two-foot trees for replacement because of their much greater survival rate.

Plant selection, both native and historic, also creates problems. The same forester believes it unlikely that native tree species will survive if planted as replacement species along ridge tops because of the high winds and salt, but the historic Monterey cypress would fare well in such locations. The historic blue gum eucalyptus tends to be very invasive, so resource managers are looking for a less invasive eucalyptus variety to use in replanting. The Monterey pine found in the historic forest is now infested with pitch pine canker, so a more pest-resistant variety is being sought.

Although the public expressed interest in seeing visual simulations of what different treatment options would look like in the future, resource managers believed this would be based on too much conjecture, given the experimental nature of replanting efforts, and so did not use simulations as part of the planning process.

Creation of a Special Management Zone

Because of the number of rare and endangered species in the southwest corner of the park, this area will be designated as a special management zone in the final VMP. Site-specific planning in this zone will require a long education process for everyone—park neighbors, outside organizations, the National Park Service, and the Presidio Trust—in order to reach a level of comfort shared by all. NPS and the trust will begin the process by assembling a team of specialists that will include, among others, a plant ecologist, an environmental specialist well versed in developing species recovery plans, and staff experienced in the public participation process. In order to cement community relations, a series of focus workshops will be held in private homes rather than on federal land.

Forest Character Study

A workshop on "Historic Forest Characterization and Treatment" was held in March 2001. The workshop focused on identifying the significant character-defining features of the Presidio's historic forest and was attended by an interdisciplinary 18-member team representing the fields of landscape architecture, forestry, natural resource management, and historic preservation. Participants were provided with information on the historic forest in the context of the overall Presidio vegetation management plan, the forest as a contributing element to the Presidio National Historic Landmark, the history and evolution of the forest and its context in relation to other land reclamation schemes promulgated at the end of the nineteenth century, the ecology and natural resource values of the forest, and the challenges presented in forest management.

The team established a goal for forest management at the site: to preserve the qualities that make the forest a contributing feature of the national historic landmark while also achieving other natural resource, management, public safety, scenic, and recreational objectives. The team also determined that the forest has significance at three scales—regional, landscape, and site—and that three aspects of the forest's history should inform the identification of character-defining features—the original design intent, initial planting, and adaptive management. The team developed a matrix specifying important character-defining features at each of the three scales for use in creating a zoned approach to management, and identified gaps in the data that would need to be filled before developing management treatments.

Mapping will be completed at the three scales to allow for a comparison of values. By working at the same scale as traditional natural resource mapping, multidisciplinary discussions can take place and opportunities for the protection of a mix of values can be identified.

Wind Shear Study

Before initiating major treatments on the Presidio's western edge, resource managers will commission a study of the windbreak function of the historic forest in that area. Compromising the windbreak integrity with major vegetation manipulations would have adverse effects on the entire Presidio.

Education in the Historic Designed Landscape

One difficulty expressed by a member of the cultural resource staff is that, while almost everyone has at least some idea about the meaning of the term "natural resource," the public does not have a clear understanding of the terms "cultural resource" and "cultural landscape." This, they believe, creates a disadvantage when advocating the preservation of the cultural landscape, and will only be overcome through education.

For example, the Presidio Trust's cultural resource staff deals regularly with tenants renting building space in the historic designed landscape who want to improve their landscaping. Because the buildings are within a national historic landmark district, only a limited array of historic plant materials can be used. The cultural resource staff works with tenants to build understanding and appreciation of the value of the historic landscape, and awareness that, historically, the landscape may have had a more stark appearance than what we are used to today.

In addition, tenants in the residential areas were interested in planting backyard vegetable gardens. Because these gardens would not have existed historically, the staff searched for an alternative and located a parcel for a community garden. The community garden serves two additional functions: a greater sense of community results from having people work together, and the garden's single contained location reduces the chance of escaped plants or seeds interfering with native vegetation.