Neighbors horrified at the prospect of a ‘chainsaw massacre’ of 1,600 eucalyptus trees on Mr. Davidson
Blue gum eucalyptus trees in Golden Gate Park
By Thomas K. Pendergast
(Originally published in the June, 2016, issue of the West Portal Monthly newspaper, a community newspaper serving the west side of San Francisco.)
In the next few months the SF Planning Department will release its final plan to cut down thousands of trees in parks throughout the City, targeting non-native or “invasive” trees like the blue gum eucalyptus, Monterey pine and Cypress pine.
The controversial plan to axe more than 3,000 non-native trees – approximately 16 percent of the urban forest – has generated fierce opposition from the surrounding communities.
Some claim that the SF Recreation and park Department’s adherence to the “native-plant agenda” of the Natural Areas Plan (NAP) ignores the legitimate concerns of local residents – as well as the findings of a number of urban forestry experts that dispute NAP’s premise for the large-scale removal of so-called “invasive” trees.
The Draft Environmental Impact Report (DEIR), published in 2011, for the 2006 Significant Natural Resources Areas Management Plan (SNRAMP), does give specific numbers of trees the SF Recreation & Park Department (RPD) is considering for removal.
According to the original SNRAMP plan, the long-term goal is to slowly convert certain areas of San Francisco’s parks to native scrub and grassland habitats or oak woodlands.
Prior to the stabilization of dunes and introduction of non-native species, trees were not a dominant feature of the San Francisco peninsula. Coast live oaks grew on north-facing slopes in moist drainages, while buckeyes, bays, and oaks lined creek channels that flowed to the bay or ocean. Much of the area, however, probably resembled the coastal scrub habitats of San Bruno Mountain or the grassland-scrub of the Marin Headlands, according to the SNRAMP.
City officials hope the removal of some trees will allow for re-vegetation with native plants, the first step in the gradual conversion of some areas from forest to scrub or grassland.
The DEIR says that invasive trees removed would be replaced with native tree species at a ratio of roughly one-to-one, although not necessarily at the same location or within the same Natural Area.
Native species being considered to replace them, according to Joey Kahn of the RPD, include oak, buckeye and alder, depending on the environment in which they would be planted.
According to the SNRAMP plan, the RPD would take into consideration the views from natural areas when locations are selected for new replacement trees; locations of such trees in San Francisco natural areas would be selected to preserve views from important points.
The largest tree cutting on the west side of the City will be at Mount Davidson, where about 1,600 trees are going to be removed out of a total 11,000 that the DEIR report classifies as “invasive.” All of them are on the 165 acres the report says are “natural areas acres.”
Tree removals are expected to occur gradually, but in the short term there will be some opening of the canopy at selected areas that may be visible from nearby vantage point.
Over the long term, tree removal will result in the conversion of some areas of forest to scrub and grasslands.
Most of Mount Davidson, however, will still support an urban forest even when tree removals are complete, according to the SNRAMP.
Neighbors around Mt. Davidson are outraged that taxpayer dollars would be spent on what they see as an ill-advised scheme to temporarily close recreation areas for the application of toxic herbicides, threaten current habitat and destroy a well-established canopy that provides both a windbreak and welcome areas for urban solitude.
And, given the threat posed by climate change, some also view the destruction of large numbers of healthy, mature trees (that help counteract the greenhouse effect) as counter-productive and short-sighted.
In the 16.5 natural areas acres of the Interior Greenbelt, adjacent to the intersection of Stanyan and 17th streets, 140 trees are slated for removal out of a total 5,800 invasive trees. Tree removal will focus on the eastern border and the western tip of the natural area, where a native vegetation restoration of the intermittent creek is planned. Eventually these areas will be converted to coastal scrub or creek riparian habitats.
Out at Lake Merced, which has a whopping 12,000 non-native trees on 395 natural area acres, 134 trees will be cut down.
“Lake Merced is a major stop-over for birds on the Pacific flyway,” says the SNRAMP summary. “Management of the urban forest will produce expanded great blue heron and double-crested cormorant nesting colonies; improved water recreation access.”
Trees will be removed from stands surrounding the lake, focused near the mesa and adjacent to the golf course on the eastern shore of South Lake. This should open up “view corridors of the lake” that are currently blocked by trees, which will remain as the forests in these areas are gradually converted to low-growing coastal scrub.
At Lake Merced, only the coast live oak is native. The remaining trees are dominated by invasive species including blue gum eucalyptus, Monterey cypress, Monterey pine, acacia, blackwood acacia, plume acacia, and lollypop trees. Many of these invasive forest stands, especially the eucalyptus stands, harbor extensive growths of invasive Cape ivy and English ivy.
The eucalyptus trees on the west shore of North and South lakes provide nesting habitat for great blue herons and double-crested cormorants.
At the 26.2 acre Oak Woodlands area of Golden Gate Park, 82 non-native trees will be removed from the 900 invasive trees now there. Almost 10 acres of the land, according to the SNRAMP, are dominated by non-native vegetation, including mixed exotic forest and blue gum eucalyptus.
Grand View Park, a four-acre plot bordering the Inner Sunset district, has 25 invasive trees, of which five will be removed; and Brooks Park, which is in the southwest part of the city, has 20 invasive trees on its two acres of natural areas, of which three will be removed.
Two methods of removing the trees are under consideration: group selection or thinning. Group selection removes a number of trees within a specified area and is used to create openings in dense forests. These sites would then be re-planted with native shrub and grasslands species.
Thinning usually occurs over large areas, several acres, removing smaller trees and saplings, while the larger trees to be removed will be individually selected. There is no specific set of criteria for choosing which trees will be removed. Instead, the selection will be based on removing unhealthy trees and the location where the invasive trees now stand.
“Tree removals would be focused in areas that still contain native biodiversity in the understory; thereby preserving what could be lost, as opposed to areas that contain no diversity and we would have to invest more resources into them to restore the biodiversity,” Kahn said.
The SNRAMP says: “In order to enhance the sensitive species habitat that persists in the urban forest understory on Mt. Davidson, for example, invasive blue gum eucalyptus trees will be removed in select areas. Coastal scrub and reed grass require additional light to reach the forest floor. Some large trees will remain, however, to minimize disturbance and disruption to wildlife and to promote a gradual conversion to reed grass prairie.”
The SNRAMP noted that as tree stands age, some of the larger trees in the stand will decline in health. Some dead trees which do not pose any public hazards and do not harbor infestations of insects or diseases, might be retained for wildlife function. If they are within 100 feet of structures maintained for human habitation they will probably be cut down.
Throughout all the City parks (but not counting Sharp Park, a city-owned golf course in Pacifica) it is estimated that 3,448 trees will be cut down over the course of the Natural Areas Program, or about 16 percent of the total urban forests.
It is also noted in the SNRAMP that “tree failures” occur when the trees on the outside of a stand are removed, thus exposing the inner trees to high winds or unstable soil conditions. In general, tree removal within the natural areas are planned to take individuals or very small groups of trees within existing forest and scrub habitats. The removal of larger numbers of trees, however, will be planned by an RPD arborist to minimize the risk of tree failure.