From the big Coast Live Oak outside City Hall, to the many neighborhoods and districts named for trees, trees are a big part of Oakland’s identity. As of 1993, four species made up 49 percent of Oakland’s tree population: blue gum (Eucalyptus globulus), Monterey pine (Pinus radiata), coast live oak (Quercus agrifolia), and California bay (Umbellularia californica)1. The City of Oakland has currently has 15 percent tree canopy; its goal (40 percent) would require 1 million new trees.2

Street Tree Data

See the city's official records that include every street tree in Oakland.

Here's a map view of the city's data (based on a geojson file available on the same page).

See how many street trees each neighborhood has.

History

In the 1850s, prior to urbanization, Oakland had a tree cover of approximately 2 percent.2 Many factors led to changes in tree cover in the Oakland area. The Ohlone harvested black Oak acorns, and used controlled burns of underbrush to do so.4 From the late 1700s to 1848, redwoods were logged from Oakland. In the late 1800s, the native oak stand was destroyed in favor of the street grid.

Massive afforestation took place in the early 1900s. In 1886, Joaquin Miller purchased 69 acres of land and planted it with pines, cypress, acacia, and eucalyptus. In the following decades, other large-scale plantings were undertaken in order to create wood for railroad building, prevent recurring fires in the hills, and increase property values. Between 1910 and 1913, Frank Havens planted 1–8 million mostly eucalyptus trees in and around the Oakland hills. Unfortunately, it was soon found that eucalyptus splits and warps when dried, making it unusable for railroad ties; its high oil content and tendency to drop much messy, flammable material made it a fire hazard, and its fast growth rate and lack of natural predators meant that it soon spread everywhere. (This, incidentally, is why it is often removed today, for example recently – and controversially – in Mountain View Cemetery.)

The City got involved in tree oversight and planting in the early 1900s, concurrent with the City Beautiful movement. According to the Greenstreets report, street tree spacing is determined in part by the average size of a parking space.

City of Oakland Tree Services

Tree Services is part of the Facilities and Environment Division of the Public Works Agency. The Tree Services website offers many resources, including guidelines for planting your own street tree or applying to have a tree removed.

Trees and Community

In 1977, a community group called Oakland Tree Task Force was formed public funding began, and used public funding to begin an inner-city tree planting program in early 1978. The organization’s planting ceremonies and general success with engaging the community have been shown to greatly reduce street tree mortality rates in comparision to trees planted without ceremony 6

Currently, Urban ReLeaf does similar work, working to plant trees in under-served neighborhoods with little to no canopy.

Environmental Issues

Keeping street trees alive means studying the trees over time.

Here's the summary of a multi-year study of Oakland's street trees:

An example of the fluxes in a street tree population comes from five years of annual monitoring in Oakland, CA [24]. The goal of this study was to understand net change in street tree population counts, in relation to annual planting and mortality (Figure 4). The West Oakland neighborhood has been the focus of recent planting efforts by both the City of Oakland and a local non-profit, Urban Releaf. These planting programs seek to provide socioeconomic benefits and address environmental injustices in an underserved community. There was an initial neighborhood street tree inventory in 2006, followed by an annual census for tree mortality, removals, and new plantings. We observed an overall population increase during the five-year study period: 995 live street trees in 2006, and 1166 in 2011, for an increase of 17%. The annual mortality rate was 3.7%, which is within the range of typical street tree mortality rates from the literature review discussed earlier. So far, so good: the mortality rates are within the “normal” range and the population is on the rise. However, mortality of small, young trees was a serious problem that prevented the population from growing even faster.

Approximately half of the 2006 trees were small, with trunks 3 inches in diameter or less. Annual mortality in that smallest size class was 5.6%, about four times the rate for all the other size classes (Figure 5). In other words, most of the tree losses came from recently planted, small trees. The planting campaigns in this neighborhood were barely out-pacing young tree deaths, and could have had a larger impact if young tree survival were enhanced. These findings support an older arboriculture study, which suggested that young street tree death drives population cycles, and the need for replacement planting [25]. The West Oakland data also supports the concept of an establishment phase for urban trees – the first few years after planting during which trees are more likely to die, [26, 27] Extra vigilance during the establishment phase, in terms of maintenance and stewardship, might have the most payoff for ensuring planting survival, and thus achieving larger canopy objectives. [source]

Trees and the Energy and Climate Action Plan

”Growing Oakland’s Urban Forest” was included in the City of Oakland Energy and Climate Action Plan as one objective in the Transportation and Land Use category. The Plan identified seven actions to be taken as part of this objective:

  • Action TLU‐45: Develop an urban forestry master plan outlining how the City will protect, develop and maintain diversified and appropriate tree plantings on City right‐of‐ways.

  • Action TLU‐46: Develop a robust urban tree inventory of all trees in proximity to sidewalks, medians, public buildings, parks and other public right‐of‐ways.

  • Action TLU‐47: Provide preventative maintenance and management of trees in City right‐of‐ways.

  • Action TLU‐48: Implement a street tree planting pilot project with local partners utilizing advanced planting techniques.

  • Action TLU‐49: Develop a plan to ensure the continued health of all parks and forested land within the city and encourage tree planting on private land throughout the community.

  • Action TLU‐50: Convene community workshops to educate community members on proper tree maintenance.

  • Action TLU‐51: Collaborate with local organizations where appropriate to advance local urban forestry efforts.

References

  1. Nowak, D. (1993), ”Historical vegetation change in Oakland and its implications for urban forest management.” ​Journal of Arboriculture 19:5, p. 313-319.
  2. https://twitter.com/Derailluer/status/276176047865749504
  3. Nowak, D. (1993). ----
  4. Environmental Studies Institute of Santa Clara University. ”History.”
  5. Nowak, D. (1993). ----
  6. Sklar, F. and Ames, R. G. (1985), ”Staying alive: Street tree survival in the inner-city.” Journal of Urban Affairs, 7: 55–66. doi: 10.1111/j.1467-9906.1985.tb00077.x